Paul H. Yi, MD

Take-Home Points

• The Flesch-Kincaid Readability Scale is a useful tool in evaluating the readability of PEMs.
• Only 1 article analyzed in our study was below a sixth-grade readability level.
• Coauthorship of PEMs with other subspecialty groups had no effect on readability.
• Poor health literacy has been associated with poor health outcomes.
• Efforts must be undertaken to make PEMs more readable across medical subspecialties.

Patients increasingly turn to the Internet to self-educate about orthopedic conditions.^1,2 Accordingly, the Internet has become a valuable tool in maintaining effective physician-patient communication.^3-5 Given the Internet’s importance as a medium for conveying patient information, it is important that orthopedic patient education materials (PEMs) on the Internet provide high-quality information that is easily read by the target patient population. Unfortunately, studies have found that many of the Internet’s orthopedic PEMs have been neither of high quality^6-8 nor presented such that they are easy for patients to read and comprehend.^1,9-12

Readability, which is the reading comprehension level (school grade level) a person must have to understand written materials, is determined by systematic formulae¹²; readability levels correlate with the ability to comprehend written information.² Studies have consistently found that orthopedic PEMs are written at readability levels too high for the average patient to understand.^1,9,13 The readability of PEMs in orthopedics as a whole⁹ and within the orthopedic subspecialties of arthroplasty,¹ foot and ankle surgery,² sports medicine,¹² and spine surgery¹³ has been evaluated, but so far there has been no evaluation of PEMs in orthopedic trauma (OT).

We conducted a study to assess the readability of OT-PEMs available online from the American Academy of Orthopaedic Surgeons (AAOS) in conjunction with the Orthopaedic Trauma Association (OTA) and other orthopedic subspecialty societies. We hypothesized the readability levels of these OT-PEMs would be above the level (sixth to eighth grade) recommended by several healthcare organizations, including the Centers for Disease Control and Prevention.^9,11,14 We also assessed the effect that orthopedic subspecialty coauthorship has on PEM readability.

Methods

In July 2014, we searched the AAOS online patient education library (Broken Bones & Injuries section, http://orthoinfo.aaos.org/menus/injury.cfm) and the AAOS OrthoPortal website (Trauma section, http://pubsearch.aaos.org/search?q=trauma&client=OrthoInfo&site=PATIENT&output=xml_no_dtd&proxystylesheet=OrthoInfo&filter=0) for all relevant OT-PEMs. Although OTA does not publish its own PEMs on its website, it coauthored several of the articles in the AAOS patient education library. Other subspecialty organizations, including the American Orthopaedic Society for Sports Medicine (AOSSM), the American Society for Surgery of the Hand (ASSH), the Pediatric Orthopaedic Society of North America (POSNA), the American Shoulder and Elbow Surgeons (ASES), the American Association of Hip and Knee Surgeons (AAHKS), and the American Orthopaedic Foot and Ankle Society (AOFAS), coauthored several of these online OT-PEMs as well.

Using the technique described by Badarudeen and Sabharwal,¹⁰ we saved all articles to be included in the study as separate Microsoft Word 2011 files. We saved them in plain-text format to remove any HTML tags and any other hidden formatting that might affect readability results. Then we edited them to remove elements that might affect readability result accuracy—deleted article topic–unrelated information (eg, copyright notice, disclaimers, author information) and all numerals, decimal points, bullets, abbreviations, paragraph breaks, colons, semicolons, and dashes.¹⁰Mr. Mohan used the Flesch-Kincaid (FK) Readability Scale to calculate grade level for each article. Microsoft Word 2011 was used as described in other investigations of orthopedic PEM readability^2,10,12,13: Its readability function is enabled by going to the Tools tab and then to the Spelling & Grammar tool, where the “Show readability statistics” option is selected.¹⁰ Readability scores are calculated with the Spelling & Grammar tool; the readability score is displayed after completion of the spelling-and-grammar check. The formula used to calculate FK grade level is¹⁵: (0.39 × average number of words per sentence) + (11.8 × average number of syllables per word) – 15.59.

Statistical Analysis

Descriptive statistics, including means and 95% confidence intervals (CIs), were calculated for the FK grade levels. Student t tests were used to compare average FK grade levels of articles written exclusively by AAOS with those of articles coauthored by AAOS and other orthopedic subspecialty societies. A 2-sample unequal-variance t test was used, and significance was set at P < .05. Total number of articles written at or below the sixth- and eighth-grade levels, the reading levels recommended for PEMs, were tabulated.^1,9-12 Intraobserver and interobserver reliabilities were calculated with intraclass correlation coefficients (ICCs): Mr. Mohan, who calculated the FK scores earlier, now 1 week later calculated the readability levels of 15 randomly selected articles^10,11; in addition, Mr. Mohan and Dr. Yi independently calculated the readability levels of 30 randomly selected articles.^10,11 The same method described earlier—edit plain-text files, then use Microsoft Word to obtain FK scores—was again used. ICCs of 0 to 0.24 correspond to poor correlation; 0.25 to 0.49, low correlation; 0.5 to 0.69, fair correlation; 0.7 to 0.89, good correlation; and 0.9 to 1.0, excellent correlation.^10,11 All statistical analyses were performed with Microsoft Excel 2011 and VassarStats (http://vassarstats.net/tu.html).

 

Results

Of the 115 AAOS website articles included in the study and reviewed, 18 were coauthored by OTA, 10 by AOSSM, 14 by POSNA, 2 by ASSH, 2 by ASES, 1 by AAHKS, 3 by AOFAS, 1 by AOSSM and ASES, and 1 by AOFAS and AOSSM.

Mean FK grade level was 9.1 (range, 6.2-12; 95% CI, 8.9-9.3) for all articles reviewed and 9.1 (range, 6.2-12; 95% CI, 8.8-9.4) for articles exclusively written by AAOS. For coauthored articles, mean FK grade level was 9.3 (range, 7.6-11.3; 95% CI, 8.8-9.8) for AAOS-OTA; 8.9 (range, 7.4-10.4; 95% CI, 8.4-9.6) for AAOS-AOSSM; 9.4 (range, 7-11.8; 95% CI, 8.9-10.1) for AAOS-POSNA; 7.8 (range, 7.8-9.1; 95% CI, 7.2-9.8) for AAOS-ASSH; 9 (range, 8.2-9.6; 95% CI, 7.6-10.2) for AAOS-ASES; 9 (range, 7.9-9; 95% CI, 7.9-9.3) for AAOS-AOFAS; 8.1 for the 1 AAOS-AAHKS article; 8.5 for the 1 AAOS-AOSSM-ASES article; and 8 for the 1 AAOS-AOFAS-AOSSM article (Figure).

Nineteen articles (16.5%) were found to be at or below the eighth-grade reading level, which is the average reading level of a US adult,¹⁰ and only 1 article was at or below the sixth-grade level, the level widely recommended for PEMs.¹¹ In addition, there was no statistically significant difference between articles coauthored by the various orthopedic subspecialties and those written exclusively by AAOS.

For FK readability calculations, interobserver reliability (ICC, 0.9982) and intraobserver reliability (ICC, 1) were both excellent.

Discussion

Although increasing numbers of patients are using information from the Internet to inform their healthcare decisions,¹² studies have shown that online PEMs are written at a readability level above that of the average patient.^1,9,13 In the present study, we also found that OT-PEMs from AAOS are written at a level considerably higher than the recommended sixth-grade reading level,¹⁶ potentially impairing patient comprehension and leading to poorer health outcomes.¹⁷

The pervasiveness of too-high PEM readability levels has been found across orthopedic subspecialties.^2,9,12,13 Following this trend, the OT articles we reviewed had a ninth-grade reading level on average, and only 1 of 115 articles was below the recommended sixth-grade level.¹⁰ The issue of too-high PEM readability levels is thus a problem both in OT and in orthopedics in general. Accordingly, efforts to address this problem are warranted, especially as orthopedic PEM readability has not substantially improved over the past several years.¹⁸In this study, we also tried to identify any readability differences between articles coauthored by orthopedic societies and articles that were not coauthored by orthopedic societies. We hypothesized that multidisciplinary authorship could improve PEM readability; for example, orthopedic societies could collaborate with other medical specialties (eg, family medicine) that have produced appropriately readable PEMs. One study found that the majority of PEMs from the American Academy of Family Physicians (AAFP) were written below the sixth-grade reading level because of strict organizational regulation of the production of such materials.¹⁹ By noting and adopting successful PEM development methods used by groups such as AAFP,^19,20 we might be able to improve OT-PEM readability. However, this was not the case in our study, though our observations may have been limited by the small sample of reviewable articles.

One factor contributing to the poor readability of orthopedic PEMs is that orthopedics terminology is complex and includes words that are often difficult to translate into simpler terms without losing their meaning.¹⁰ When PEMs are written at a level that is too complex, patients cannot fully comprehend them, which may lead to poor health literacy. This problem may be even more harmful when considering the poor literacy levels of patients at baseline. Kadakia and colleagues¹⁶ found that OT patients had poor health literacy; for example, fewer than half knew which bone they fractured. As health literacy is associated with poorer health outcomes and reduced use of healthcare services,²¹ optimizing patients’ health literacy is of crucial importance to both their education and their outcomes.

Our study should be viewed in light of some important limitations. As OTA does not publish its own PEMs, we assessed only OT-related articles that were available on the AAOS website and were exclusively written by AAOS, or coauthored by AAOS and by OTA and/or another orthopedic subspecialty organization. As these articles represent only a subset of the full spectrum of OT-PEMs available on the Internet, our results may not be generalizable to the entire scope of such materials. However, as AAOS and OTA represent the most authoritative OT organizations, we think these PEMs would be among those most likely to be recommended to patients by their surgeons. In addition, although we used a well-established tool for examining readability—the FK readability scale^10-13—this tool has its own inherent limitations, as FK readability grade level is calculated purely on the basis of words per sentence and total syllables per word, and does not take into account other article elements, such as images, which also provide information.^1,10 Nevertheless, the FK scale is an inexpensive, easily accessed readability tool that provides a reproducible readability value that is easily comparable to results from earlier studies.¹⁰ The final limitation is that we excluded from the study AAOS website articles written in a language other than English. Such articles, however, are important, as a large portion of the patient population speaks English as a second language. Indeed, the readability of Spanish PEMs has been investigated—albeit using a readability measure other than the FK scale—and may be a topic pertinent to orthopedic PEMs.²²Most of the literature on the readability of orthopedic PEMs has found their reading levels too high for the average patient to comprehend.^1,9-12 The trend continues with our study findings regarding OT-PEMs available online from AAOS. Although the literature on the inadequacies of orthopedic PEMs is vast,^1,9-12 more work is needed to improve the quality, accuracy, and readability of these materials. There has been some success in improving PEM readability and producing appropriately readable materials within the medical profession,^19,23 so we know that appropriately readable orthopedic PEMs are feasible.

Am J Orthop. 2017;46(3):E190-E194. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

 

Take-Home Points

• The Flesch-Kincaid Readability Scale is a useful tool in evaluating the readability of PEMs.
• Only 1 article analyzed in our study was below a sixth-grade readability level.
• Coauthorship of PEMs with other subspecialty groups had no effect on readability.
• Poor health literacy has been associated with poor health outcomes.
• Efforts must be undertaken to make PEMs more readable across medical subspecialties.

Patients increasingly turn to the Internet to self-educate about orthopedic conditions.^1,2 Accordingly, the Internet has become a valuable tool in maintaining effective physician-patient communication.^3-5 Given the Internet’s importance as a medium for conveying patient information, it is important that orthopedic patient education materials (PEMs) on the Internet provide high-quality information that is easily read by the target patient population. Unfortunately, studies have found that many of the Internet’s orthopedic PEMs have been neither of high quality^6-8 nor presented such that they are easy for patients to read and comprehend.^1,9-12

Readability, which is the reading comprehension level (school grade level) a person must have to understand written materials, is determined by systematic formulae¹²; readability levels correlate with the ability to comprehend written information.² Studies have consistently found that orthopedic PEMs are written at readability levels too high for the average patient to understand.^1,9,13 The readability of PEMs in orthopedics as a whole⁹ and within the orthopedic subspecialties of arthroplasty,¹ foot and ankle surgery,² sports medicine,¹² and spine surgery¹³ has been evaluated, but so far there has been no evaluation of PEMs in orthopedic trauma (OT).

We conducted a study to assess the readability of OT-PEMs available online from the American Academy of Orthopaedic Surgeons (AAOS) in conjunction with the Orthopaedic Trauma Association (OTA) and other orthopedic subspecialty societies. We hypothesized the readability levels of these OT-PEMs would be above the level (sixth to eighth grade) recommended by several healthcare organizations, including the Centers for Disease Control and Prevention.^9,11,14 We also assessed the effect that orthopedic subspecialty coauthorship has on PEM readability.

Methods

In July 2014, we searched the AAOS online patient education library (Broken Bones & Injuries section, http://orthoinfo.aaos.org/menus/injury.cfm) and the AAOS OrthoPortal website (Trauma section, http://pubsearch.aaos.org/search?q=trauma&client=OrthoInfo&site=PATIENT&output=xml_no_dtd&proxystylesheet=OrthoInfo&filter=0) for all relevant OT-PEMs. Although OTA does not publish its own PEMs on its website, it coauthored several of the articles in the AAOS patient education library. Other subspecialty organizations, including the American Orthopaedic Society for Sports Medicine (AOSSM), the American Society for Surgery of the Hand (ASSH), the Pediatric Orthopaedic Society of North America (POSNA), the American Shoulder and Elbow Surgeons (ASES), the American Association of Hip and Knee Surgeons (AAHKS), and the American Orthopaedic Foot and Ankle Society (AOFAS), coauthored several of these online OT-PEMs as well.

Using the technique described by Badarudeen and Sabharwal,¹⁰ we saved all articles to be included in the study as separate Microsoft Word 2011 files. We saved them in plain-text format to remove any HTML tags and any other hidden formatting that might affect readability results. Then we edited them to remove elements that might affect readability result accuracy—deleted article topic–unrelated information (eg, copyright notice, disclaimers, author information) and all numerals, decimal points, bullets, abbreviations, paragraph breaks, colons, semicolons, and dashes.¹⁰Mr. Mohan used the Flesch-Kincaid (FK) Readability Scale to calculate grade level for each article. Microsoft Word 2011 was used as described in other investigations of orthopedic PEM readability^2,10,12,13: Its readability function is enabled by going to the Tools tab and then to the Spelling & Grammar tool, where the “Show readability statistics” option is selected.¹⁰ Readability scores are calculated with the Spelling & Grammar tool; the readability score is displayed after completion of the spelling-and-grammar check. The formula used to calculate FK grade level is¹⁵: (0.39 × average number of words per sentence) + (11.8 × average number of syllables per word) – 15.59.

Statistical Analysis

Descriptive statistics, including means and 95% confidence intervals (CIs), were calculated for the FK grade levels. Student t tests were used to compare average FK grade levels of articles written exclusively by AAOS with those of articles coauthored by AAOS and other orthopedic subspecialty societies. A 2-sample unequal-variance t test was used, and significance was set at P < .05. Total number of articles written at or below the sixth- and eighth-grade levels, the reading levels recommended for PEMs, were tabulated.^1,9-12 Intraobserver and interobserver reliabilities were calculated with intraclass correlation coefficients (ICCs): Mr. Mohan, who calculated the FK scores earlier, now 1 week later calculated the readability levels of 15 randomly selected articles^10,11; in addition, Mr. Mohan and Dr. Yi independently calculated the readability levels of 30 randomly selected articles.^10,11 The same method described earlier—edit plain-text files, then use Microsoft Word to obtain FK scores—was again used. ICCs of 0 to 0.24 correspond to poor correlation; 0.25 to 0.49, low correlation; 0.5 to 0.69, fair correlation; 0.7 to 0.89, good correlation; and 0.9 to 1.0, excellent correlation.^10,11 All statistical analyses were performed with Microsoft Excel 2011 and VassarStats (http://vassarstats.net/tu.html).

 

Results

Of the 115 AAOS website articles included in the study and reviewed, 18 were coauthored by OTA, 10 by AOSSM, 14 by POSNA, 2 by ASSH, 2 by ASES, 1 by AAHKS, 3 by AOFAS, 1 by AOSSM and ASES, and 1 by AOFAS and AOSSM.

Mean FK grade level was 9.1 (range, 6.2-12; 95% CI, 8.9-9.3) for all articles reviewed and 9.1 (range, 6.2-12; 95% CI, 8.8-9.4) for articles exclusively written by AAOS. For coauthored articles, mean FK grade level was 9.3 (range, 7.6-11.3; 95% CI, 8.8-9.8) for AAOS-OTA; 8.9 (range, 7.4-10.4; 95% CI, 8.4-9.6) for AAOS-AOSSM; 9.4 (range, 7-11.8; 95% CI, 8.9-10.1) for AAOS-POSNA; 7.8 (range, 7.8-9.1; 95% CI, 7.2-9.8) for AAOS-ASSH; 9 (range, 8.2-9.6; 95% CI, 7.6-10.2) for AAOS-ASES; 9 (range, 7.9-9; 95% CI, 7.9-9.3) for AAOS-AOFAS; 8.1 for the 1 AAOS-AAHKS article; 8.5 for the 1 AAOS-AOSSM-ASES article; and 8 for the 1 AAOS-AOFAS-AOSSM article (Figure).

Nineteen articles (16.5%) were found to be at or below the eighth-grade reading level, which is the average reading level of a US adult,¹⁰ and only 1 article was at or below the sixth-grade level, the level widely recommended for PEMs.¹¹ In addition, there was no statistically significant difference between articles coauthored by the various orthopedic subspecialties and those written exclusively by AAOS.

For FK readability calculations, interobserver reliability (ICC, 0.9982) and intraobserver reliability (ICC, 1) were both excellent.

Discussion

Although increasing numbers of patients are using information from the Internet to inform their healthcare decisions,¹² studies have shown that online PEMs are written at a readability level above that of the average patient.^1,9,13 In the present study, we also found that OT-PEMs from AAOS are written at a level considerably higher than the recommended sixth-grade reading level,¹⁶ potentially impairing patient comprehension and leading to poorer health outcomes.¹⁷

The pervasiveness of too-high PEM readability levels has been found across orthopedic subspecialties.^2,9,12,13 Following this trend, the OT articles we reviewed had a ninth-grade reading level on average, and only 1 of 115 articles was below the recommended sixth-grade level.¹⁰ The issue of too-high PEM readability levels is thus a problem both in OT and in orthopedics in general. Accordingly, efforts to address this problem are warranted, especially as orthopedic PEM readability has not substantially improved over the past several years.¹⁸In this study, we also tried to identify any readability differences between articles coauthored by orthopedic societies and articles that were not coauthored by orthopedic societies. We hypothesized that multidisciplinary authorship could improve PEM readability; for example, orthopedic societies could collaborate with other medical specialties (eg, family medicine) that have produced appropriately readable PEMs. One study found that the majority of PEMs from the American Academy of Family Physicians (AAFP) were written below the sixth-grade reading level because of strict organizational regulation of the production of such materials.¹⁹ By noting and adopting successful PEM development methods used by groups such as AAFP,^19,20 we might be able to improve OT-PEM readability. However, this was not the case in our study, though our observations may have been limited by the small sample of reviewable articles.

One factor contributing to the poor readability of orthopedic PEMs is that orthopedics terminology is complex and includes words that are often difficult to translate into simpler terms without losing their meaning.¹⁰ When PEMs are written at a level that is too complex, patients cannot fully comprehend them, which may lead to poor health literacy. This problem may be even more harmful when considering the poor literacy levels of patients at baseline. Kadakia and colleagues¹⁶ found that OT patients had poor health literacy; for example, fewer than half knew which bone they fractured. As health literacy is associated with poorer health outcomes and reduced use of healthcare services,²¹ optimizing patients’ health literacy is of crucial importance to both their education and their outcomes.

Our study should be viewed in light of some important limitations. As OTA does not publish its own PEMs, we assessed only OT-related articles that were available on the AAOS website and were exclusively written by AAOS, or coauthored by AAOS and by OTA and/or another orthopedic subspecialty organization. As these articles represent only a subset of the full spectrum of OT-PEMs available on the Internet, our results may not be generalizable to the entire scope of such materials. However, as AAOS and OTA represent the most authoritative OT organizations, we think these PEMs would be among those most likely to be recommended to patients by their surgeons. In addition, although we used a well-established tool for examining readability—the FK readability scale^10-13—this tool has its own inherent limitations, as FK readability grade level is calculated purely on the basis of words per sentence and total syllables per word, and does not take into account other article elements, such as images, which also provide information.^1,10 Nevertheless, the FK scale is an inexpensive, easily accessed readability tool that provides a reproducible readability value that is easily comparable to results from earlier studies.¹⁰ The final limitation is that we excluded from the study AAOS website articles written in a language other than English. Such articles, however, are important, as a large portion of the patient population speaks English as a second language. Indeed, the readability of Spanish PEMs has been investigated—albeit using a readability measure other than the FK scale—and may be a topic pertinent to orthopedic PEMs.²²Most of the literature on the readability of orthopedic PEMs has found their reading levels too high for the average patient to comprehend.^1,9-12 The trend continues with our study findings regarding OT-PEMs available online from AAOS. Although the literature on the inadequacies of orthopedic PEMs is vast,^1,9-12 more work is needed to improve the quality, accuracy, and readability of these materials. There has been some success in improving PEM readability and producing appropriately readable materials within the medical profession,^19,23 so we know that appropriately readable orthopedic PEMs are feasible.

Am J Orthop. 2017;46(3):E190-E194. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

 

Take-Home Points

• The Flesch-Kincaid Readability Scale is a useful tool in evaluating the readability of PEMs.
• Only 1 article analyzed in our study was below a sixth-grade readability level.
• Coauthorship of PEMs with other subspecialty groups had no effect on readability.
• Poor health literacy has been associated with poor health outcomes.
• Efforts must be undertaken to make PEMs more readable across medical subspecialties.

Patients increasingly turn to the Internet to self-educate about orthopedic conditions.^1,2 Accordingly, the Internet has become a valuable tool in maintaining effective physician-patient communication.^3-5 Given the Internet’s importance as a medium for conveying patient information, it is important that orthopedic patient education materials (PEMs) on the Internet provide high-quality information that is easily read by the target patient population. Unfortunately, studies have found that many of the Internet’s orthopedic PEMs have been neither of high quality^6-8 nor presented such that they are easy for patients to read and comprehend.^1,9-12

Readability, which is the reading comprehension level (school grade level) a person must have to understand written materials, is determined by systematic formulae¹²; readability levels correlate with the ability to comprehend written information.² Studies have consistently found that orthopedic PEMs are written at readability levels too high for the average patient to understand.^1,9,13 The readability of PEMs in orthopedics as a whole⁹ and within the orthopedic subspecialties of arthroplasty,¹ foot and ankle surgery,² sports medicine,¹² and spine surgery¹³ has been evaluated, but so far there has been no evaluation of PEMs in orthopedic trauma (OT).

We conducted a study to assess the readability of OT-PEMs available online from the American Academy of Orthopaedic Surgeons (AAOS) in conjunction with the Orthopaedic Trauma Association (OTA) and other orthopedic subspecialty societies. We hypothesized the readability levels of these OT-PEMs would be above the level (sixth to eighth grade) recommended by several healthcare organizations, including the Centers for Disease Control and Prevention.^9,11,14 We also assessed the effect that orthopedic subspecialty coauthorship has on PEM readability.

Methods

In July 2014, we searched the AAOS online patient education library (Broken Bones & Injuries section, http://orthoinfo.aaos.org/menus/injury.cfm) and the AAOS OrthoPortal website (Trauma section, http://pubsearch.aaos.org/search?q=trauma&client=OrthoInfo&site=PATIENT&output=xml_no_dtd&proxystylesheet=OrthoInfo&filter=0) for all relevant OT-PEMs. Although OTA does not publish its own PEMs on its website, it coauthored several of the articles in the AAOS patient education library. Other subspecialty organizations, including the American Orthopaedic Society for Sports Medicine (AOSSM), the American Society for Surgery of the Hand (ASSH), the Pediatric Orthopaedic Society of North America (POSNA), the American Shoulder and Elbow Surgeons (ASES), the American Association of Hip and Knee Surgeons (AAHKS), and the American Orthopaedic Foot and Ankle Society (AOFAS), coauthored several of these online OT-PEMs as well.

Using the technique described by Badarudeen and Sabharwal,¹⁰ we saved all articles to be included in the study as separate Microsoft Word 2011 files. We saved them in plain-text format to remove any HTML tags and any other hidden formatting that might affect readability results. Then we edited them to remove elements that might affect readability result accuracy—deleted article topic–unrelated information (eg, copyright notice, disclaimers, author information) and all numerals, decimal points, bullets, abbreviations, paragraph breaks, colons, semicolons, and dashes.¹⁰Mr. Mohan used the Flesch-Kincaid (FK) Readability Scale to calculate grade level for each article. Microsoft Word 2011 was used as described in other investigations of orthopedic PEM readability^2,10,12,13: Its readability function is enabled by going to the Tools tab and then to the Spelling & Grammar tool, where the “Show readability statistics” option is selected.¹⁰ Readability scores are calculated with the Spelling & Grammar tool; the readability score is displayed after completion of the spelling-and-grammar check. The formula used to calculate FK grade level is¹⁵: (0.39 × average number of words per sentence) + (11.8 × average number of syllables per word) – 15.59.

Statistical Analysis

Descriptive statistics, including means and 95% confidence intervals (CIs), were calculated for the FK grade levels. Student t tests were used to compare average FK grade levels of articles written exclusively by AAOS with those of articles coauthored by AAOS and other orthopedic subspecialty societies. A 2-sample unequal-variance t test was used, and significance was set at P < .05. Total number of articles written at or below the sixth- and eighth-grade levels, the reading levels recommended for PEMs, were tabulated.^1,9-12 Intraobserver and interobserver reliabilities were calculated with intraclass correlation coefficients (ICCs): Mr. Mohan, who calculated the FK scores earlier, now 1 week later calculated the readability levels of 15 randomly selected articles^10,11; in addition, Mr. Mohan and Dr. Yi independently calculated the readability levels of 30 randomly selected articles.^10,11 The same method described earlier—edit plain-text files, then use Microsoft Word to obtain FK scores—was again used. ICCs of 0 to 0.24 correspond to poor correlation; 0.25 to 0.49, low correlation; 0.5 to 0.69, fair correlation; 0.7 to 0.89, good correlation; and 0.9 to 1.0, excellent correlation.^10,11 All statistical analyses were performed with Microsoft Excel 2011 and VassarStats (http://vassarstats.net/tu.html).

 

Results

Of the 115 AAOS website articles included in the study and reviewed, 18 were coauthored by OTA, 10 by AOSSM, 14 by POSNA, 2 by ASSH, 2 by ASES, 1 by AAHKS, 3 by AOFAS, 1 by AOSSM and ASES, and 1 by AOFAS and AOSSM.

Mean FK grade level was 9.1 (range, 6.2-12; 95% CI, 8.9-9.3) for all articles reviewed and 9.1 (range, 6.2-12; 95% CI, 8.8-9.4) for articles exclusively written by AAOS. For coauthored articles, mean FK grade level was 9.3 (range, 7.6-11.3; 95% CI, 8.8-9.8) for AAOS-OTA; 8.9 (range, 7.4-10.4; 95% CI, 8.4-9.6) for AAOS-AOSSM; 9.4 (range, 7-11.8; 95% CI, 8.9-10.1) for AAOS-POSNA; 7.8 (range, 7.8-9.1; 95% CI, 7.2-9.8) for AAOS-ASSH; 9 (range, 8.2-9.6; 95% CI, 7.6-10.2) for AAOS-ASES; 9 (range, 7.9-9; 95% CI, 7.9-9.3) for AAOS-AOFAS; 8.1 for the 1 AAOS-AAHKS article; 8.5 for the 1 AAOS-AOSSM-ASES article; and 8 for the 1 AAOS-AOFAS-AOSSM article (Figure).

Nineteen articles (16.5%) were found to be at or below the eighth-grade reading level, which is the average reading level of a US adult,¹⁰ and only 1 article was at or below the sixth-grade level, the level widely recommended for PEMs.¹¹ In addition, there was no statistically significant difference between articles coauthored by the various orthopedic subspecialties and those written exclusively by AAOS.

For FK readability calculations, interobserver reliability (ICC, 0.9982) and intraobserver reliability (ICC, 1) were both excellent.

Discussion

Although increasing numbers of patients are using information from the Internet to inform their healthcare decisions,¹² studies have shown that online PEMs are written at a readability level above that of the average patient.^1,9,13 In the present study, we also found that OT-PEMs from AAOS are written at a level considerably higher than the recommended sixth-grade reading level,¹⁶ potentially impairing patient comprehension and leading to poorer health outcomes.¹⁷

The pervasiveness of too-high PEM readability levels has been found across orthopedic subspecialties.^2,9,12,13 Following this trend, the OT articles we reviewed had a ninth-grade reading level on average, and only 1 of 115 articles was below the recommended sixth-grade level.¹⁰ The issue of too-high PEM readability levels is thus a problem both in OT and in orthopedics in general. Accordingly, efforts to address this problem are warranted, especially as orthopedic PEM readability has not substantially improved over the past several years.¹⁸In this study, we also tried to identify any readability differences between articles coauthored by orthopedic societies and articles that were not coauthored by orthopedic societies. We hypothesized that multidisciplinary authorship could improve PEM readability; for example, orthopedic societies could collaborate with other medical specialties (eg, family medicine) that have produced appropriately readable PEMs. One study found that the majority of PEMs from the American Academy of Family Physicians (AAFP) were written below the sixth-grade reading level because of strict organizational regulation of the production of such materials.¹⁹ By noting and adopting successful PEM development methods used by groups such as AAFP,^19,20 we might be able to improve OT-PEM readability. However, this was not the case in our study, though our observations may have been limited by the small sample of reviewable articles.

One factor contributing to the poor readability of orthopedic PEMs is that orthopedics terminology is complex and includes words that are often difficult to translate into simpler terms without losing their meaning.¹⁰ When PEMs are written at a level that is too complex, patients cannot fully comprehend them, which may lead to poor health literacy. This problem may be even more harmful when considering the poor literacy levels of patients at baseline. Kadakia and colleagues¹⁶ found that OT patients had poor health literacy; for example, fewer than half knew which bone they fractured. As health literacy is associated with poorer health outcomes and reduced use of healthcare services,²¹ optimizing patients’ health literacy is of crucial importance to both their education and their outcomes.

Our study should be viewed in light of some important limitations. As OTA does not publish its own PEMs, we assessed only OT-related articles that were available on the AAOS website and were exclusively written by AAOS, or coauthored by AAOS and by OTA and/or another orthopedic subspecialty organization. As these articles represent only a subset of the full spectrum of OT-PEMs available on the Internet, our results may not be generalizable to the entire scope of such materials. However, as AAOS and OTA represent the most authoritative OT organizations, we think these PEMs would be among those most likely to be recommended to patients by their surgeons. In addition, although we used a well-established tool for examining readability—the FK readability scale^10-13—this tool has its own inherent limitations, as FK readability grade level is calculated purely on the basis of words per sentence and total syllables per word, and does not take into account other article elements, such as images, which also provide information.^1,10 Nevertheless, the FK scale is an inexpensive, easily accessed readability tool that provides a reproducible readability value that is easily comparable to results from earlier studies.¹⁰ The final limitation is that we excluded from the study AAOS website articles written in a language other than English. Such articles, however, are important, as a large portion of the patient population speaks English as a second language. Indeed, the readability of Spanish PEMs has been investigated—albeit using a readability measure other than the FK scale—and may be a topic pertinent to orthopedic PEMs.²²Most of the literature on the readability of orthopedic PEMs has found their reading levels too high for the average patient to comprehend.^1,9-12 The trend continues with our study findings regarding OT-PEMs available online from AAOS. Although the literature on the inadequacies of orthopedic PEMs is vast,^1,9-12 more work is needed to improve the quality, accuracy, and readability of these materials. There has been some success in improving PEM readability and producing appropriately readable materials within the medical profession,^19,23 so we know that appropriately readable orthopedic PEMs are feasible.

Am J Orthop. 2017;46(3):E190-E194. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

 

Leg-length discrepancy (LLD) is common in the general population¹ and particularly in patients with degenerative joint diseases of the hip and knee.² Common complications of LLD include femoral, sciatic, and peroneal nerve palsy; lower back pain; gait abnormalities³; and general dissatisfaction. LLD is a concern for orthopedic surgeons who perform total knee arthroplasty (TKA) because limb lengthening is common after this procedure.^4,5 Surgeons are aware of the limb lengthening that occurs during TKA,^4,5 and studies have confirmed that LLD usually decreases after TKA.^4,5

Despite surgeons’ best efforts, some patients still perceive LLD after surgery, though the incidence of perceived LLD in patients who have had TKA has not been well documented. Aside from actual, objectively measured LLD, there may be other factors that lead patients to perceive LLD. Study results have suggested that preoperative varus–valgus alignment of the knee joint may correlate with how much an operative leg is lengthened after TKA^4,5; however, the outcome investigated was objective LLD measurements, not perceived LLD. Understanding the factors that may influence patients’ ability to perceive LLD would allow surgeons to preoperatively identify patients who are at higher risk for postoperative perceived LLD. This information, along with expected time to resolution of postoperative perceived LLD, would allow surgeons to educate their patients accordingly.

We conducted a study to determine the incidence of perceived LLD before and after primary TKA in patients with unilateral osteoarthritis and to determine the correlation between mechanical axis of the knee and perceived LLD before and after surgery. Given that surgery may correct mechanical axis misalignment, we investigated the correlation between this correction and its ability to change patients’ preoperative and postoperative perceived LLD. We hypothesized that a large correction of mechanical axis would lead patients to perceive LLD after surgery. The relationship of body mass index (BMI) and age to patients’ perceived LLD was also assessed. The incidence and time frame of resolution of postoperative perceived LLD were determined.

Methods

Approval for this study was received from the Institutional Review Board at our institution, Rush University Medical Center in Chicago, Illinois. Seventy-three patients undergoing primary TKA performed by 3 surgeons at 2 institutions between February 2010 and January 2013 were prospectively enrolled. Inclusion criteria were age 18 years to 90 years and primary TKA for unilateral osteoarthritis; exclusion criteria were allergy or intolerance to the study materials, operative treatment of affected joint or its underlying etiology within prior month, previous surgeries (other than arthroscopy) on affected joint, previous surgeries (on unaffected lower extremity) that may influence preoperative and postoperative leg lengths, and any substance abuse or dependence within the past 6 months. Patients provided written informed consent for total knee arthroplasty.

All surgeries were performed by Dr. Levine, Dr. Della Valle, and Dr. Sporer using the medial parapatellar or midvastus approach with tourniquet. Similar standard postoperative rehabilitation protocols with early mobilization were used in all cases.

During clinical evaluation, patient demographic data were collected and LLD surveys administered. Patients were asked, before surgery and 3 to 6 weeks, 3 months, 6 months, and 1 year after surgery, if they perceived LLD. A patient who no longer perceived LLD after surgery was no longer followed for this study.

At the preoperative clinic visit and at the 3-month or 6-week postoperative visit, standing mechanical axis radiographs were viewed by 2 of the authors (not the primary surgeons) using PACS (picture archiving and communication system software). The mechanical axis of the operative leg was measured with ImageJ software by taking the angle from the center of the femur to the middle of the ankle joint, with the vertex assigned to the middle of the knee joint.

We used a 2-tailed unpaired t test to determine the relationship of preoperative mechanical axis to perceived LLD (or lack thereof) before surgery. The data were analyzed for separate varus and valgus deformities. Then we determined the relationship of postoperative mechanical axis to perceived LLD (or lack thereof) after surgery. The McNemar test was used to determine the effect of surgery on patients’ LLD perceptions.

To determine the relationship between preoperative-to-postoperative change in mechanical axis and change in LLD perceptions, we divided patients into 4 groups. Group 1 had both preoperative and postoperative perceived LLD, group 2 had no preoperative or postoperative perceived LLD, group 3 had preoperative perceived LLD but no postoperative perceived LLD, and group 4 had postoperative perceived LLD but no preoperative perceived LLD. The absolute value of the difference between preoperative and postoperative mechanical axis was then determined, relative to 180°, to account for changes in varus to valgus deformity before and after surgery and vice versa. Analysis of variance (ANOVA) was used to detect differences between groups. This analysis was then stratified based on BMI and age.

 

Results

Of the 73 enrolled patients, 2 were excluded from results analysis because of inadequate data—one did not complete the postoperative LLD survey, and the other did not have postoperative standing mechanical axis radiographs—leaving 71 patients (27 men, 44 women) with adequate data. Mean (SD) age of all patients was 65 (8.4) years (range, 47-89 years). Mean (SD) BMI was 35.1 (9.9; range, 20.2-74.8).

Of the 71 patients with adequate data, 18 had preoperative perceived LLD and 53 did not; in addition, 7 had postoperative perceived LLD and 64 did not. All 7 patients with postoperative perceived LLD noted resolution of LLD, at a mean of 8.5 weeks (range, 3 weeks-3 months). There was a significant difference between the 18 patients with preoperative perceived LLD and the 7 with postoperative perceived LLD (P = .035, analyzed with the McNemar test).

Table 1 lists the mean preoperative mechanical axis measurements for patients with and without preoperative perceived LLD.

There was no significant difference between the 2 groups (P = .27). There was also no significant difference in preoperative mechanical axis when cases were separated and analyzed as varus and valgus deformities (varus P = .53, valgus P = .20).

Table 2 lists the mean postoperative mechanical axis measurements for patients with and without postoperative perceived LLD.

There was no significant difference between the 2 groups (P = .42). There was also no significant difference in postoperative mechanical axis for separate varus (P = .29) and valgus (P = .52) deformities.

Table 3 lists the mean absolute values of mechanical axis correction (preoperative to postoperative) for the 4 patient groups described in the Methods section.

ANOVA revealed no significant statistical difference in these values among the groups (P = .9229). There were also no significant statistical differences when the groups were stratified by age (40-59.9 years, P = .5973; 60-69.9 years, P = .6263; 70 years or older, P = .3779) or when ANOVA was used to compare the groups’ mean ages (P = .3183). In addition, the 4 groups were not significantly statistically different in BMI: obese (BMI >30; P = .3891) and nonobese (BMI <29.9; P = .9862).

Discussion

In this study, 18 patients (25%) had preoperative perceived LLD, proving that perceived LLD is common in patients who undergo TKA for unilateral osteoarthritis. Surgeons should give their patients a preoperative survey on perceived LLD, as survey responses may inform and influence surgical decisions and strategies.

Of the 18 patients with preoperative perceived LLD, only 1 had postoperative perceived LLD. That perceived LLD decreased after surgery makes sense given the widely accepted notion that actual LLD is common before primary TKA but in most cases is corrected during surgery.^4,5 As LLD correction during surgery is so successful, surgeons should tell their patients with preoperative perceived LLD that in most cases it will be fixed after TKA.

Although the incidence of perceived LLD decreased after TKA (as mentioned earlier), the decrease seemed to be restricted mostly to patients with preoperative perceived LLD, and the underlying LLD was most probably corrected by the surgery. However, surgery introduced perceived LLD in 6 cases, supporting the notion that it is crucial to understand which patients are at higher risk for postoperative perceived LLD and what if any time frame can be expected for resolution in these cases. In our study, all cases of perceived LLD had resolved by a mean follow-up of 8.5 weeks (range, 3 weeks-3 months). This phenomenon of resolution may be attributed to some of the physical, objective LLD corrections that naturally occur throughout the postoperative course,⁴ though psychological factors may also be involved. Our study results suggest patients should be counseled that, though about 10% of patients perceive LLD after primary TKA, the vast majority of perceived LLD cases resolve within 3 months.

One study goal was to determine the relationship between the mechanical axis of the knee and perceived LLD both before and after surgery. There were no significant relationships. This was also true when cases of varus and valgus deformity were analyzed separately.

Another study goal was to determine if a surgical change in the mechanical alignment of the knee would influence preoperative-to-postoperative LLD perceptions. In our analysis, patients were divided into 4 groups based on their preoperative and postoperative LLD perceptions (see Methods section). ANOVA revealed no significant differences in absolute values of mechanical axis correction among the 4 groups. Likewise, there were no correlations between BMI and age and mechanical axis correction among the groups, suggesting LLD perception is unrelated to any of these variables. Ideally, if a relationship between a threshold knee alignment value and perceived LLD existed, surgeons would be able to counsel patients at higher risk for perceived LLD about how their knee alignment may contribute to their perception. Unfortunately, our study results did not show any significant statistical relationships in this regard.

The problem of LLD in patients undergoing TKA is not new, and much research is needed to determine the correlation between perceived versus actual discrepancies, and why they occur. Our study results confirmed that TKA corrects most cases of preoperative perceived LLD but introduces perceived LLD in other cases. Whether preoperative or postoperative LLD is merely perceived or is in fact an actual discrepancy remains to be seen.

One limitation of this study was its lack of leg-length measurements. Although we studied knee alignment specifically, it would have been useful to compare perceived LLD with measured leg lengths, either clinically or radiographically, especially since leg lengths obviously play a role in any perceived LLD. We used mechanical alignment as a surrogate for actual LLD because we hypothesized that alignment may contribute to patients’ perceived discrepancies.

Another limitation was the relatively small sample. Only 24 cases of perceived LLD were analyzed. Given our low rates of perceived LLD (25% before surgery, 10% after surgery), it is difficult to study a large enough TKA group to establish a statistically significant number of cases. Nevertheless, investigators may use larger groups to establish more meaningful relationships.

A third limitation was that alignment was measured on the operative side but not the contralateral side. As we were focusing on perceived discrepancy, contralateral knee alignment may play an important role. Our study involved patients with unilateral osteoarthritis, so it would be reasonable to assume the nonoperative knee was almost neutral in alignment in most cases. However, given that varus/valgus misalignment is a known risk factor for osteoarthritis,⁶ many of our patients with unilateral disease may very well have had preexisting misalignment of both knees. The undetermined alignment of the nonoperative side may be a confounding variable in the relationship between operative knee alignment and perceived LLD.

Fourth, not all patients were surveyed 3 weeks after surgery. Some were first surveyed at 6 weeks, and it is possible there were cases of transient postoperative LLD that resolved before that point. Therefore, our reported incidence of postoperative LLD could have missed some cases. In addition, our mean 8.5-week period for LLD resolution may not have accounted for these resolved cases of transient perceived LLD.

Am J Orthop. 2016;45(7):E429-E433. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

Leg-length discrepancy (LLD) is common in the general population¹ and particularly in patients with degenerative joint diseases of the hip and knee.² Common complications of LLD include femoral, sciatic, and peroneal nerve palsy; lower back pain; gait abnormalities³; and general dissatisfaction. LLD is a concern for orthopedic surgeons who perform total knee arthroplasty (TKA) because limb lengthening is common after this procedure.^4,5 Surgeons are aware of the limb lengthening that occurs during TKA,^4,5 and studies have confirmed that LLD usually decreases after TKA.^4,5

Despite surgeons’ best efforts, some patients still perceive LLD after surgery, though the incidence of perceived LLD in patients who have had TKA has not been well documented. Aside from actual, objectively measured LLD, there may be other factors that lead patients to perceive LLD. Study results have suggested that preoperative varus–valgus alignment of the knee joint may correlate with how much an operative leg is lengthened after TKA^4,5; however, the outcome investigated was objective LLD measurements, not perceived LLD. Understanding the factors that may influence patients’ ability to perceive LLD would allow surgeons to preoperatively identify patients who are at higher risk for postoperative perceived LLD. This information, along with expected time to resolution of postoperative perceived LLD, would allow surgeons to educate their patients accordingly.

We conducted a study to determine the incidence of perceived LLD before and after primary TKA in patients with unilateral osteoarthritis and to determine the correlation between mechanical axis of the knee and perceived LLD before and after surgery. Given that surgery may correct mechanical axis misalignment, we investigated the correlation between this correction and its ability to change patients’ preoperative and postoperative perceived LLD. We hypothesized that a large correction of mechanical axis would lead patients to perceive LLD after surgery. The relationship of body mass index (BMI) and age to patients’ perceived LLD was also assessed. The incidence and time frame of resolution of postoperative perceived LLD were determined.

Methods

Approval for this study was received from the Institutional Review Board at our institution, Rush University Medical Center in Chicago, Illinois. Seventy-three patients undergoing primary TKA performed by 3 surgeons at 2 institutions between February 2010 and January 2013 were prospectively enrolled. Inclusion criteria were age 18 years to 90 years and primary TKA for unilateral osteoarthritis; exclusion criteria were allergy or intolerance to the study materials, operative treatment of affected joint or its underlying etiology within prior month, previous surgeries (other than arthroscopy) on affected joint, previous surgeries (on unaffected lower extremity) that may influence preoperative and postoperative leg lengths, and any substance abuse or dependence within the past 6 months. Patients provided written informed consent for total knee arthroplasty.

All surgeries were performed by Dr. Levine, Dr. Della Valle, and Dr. Sporer using the medial parapatellar or midvastus approach with tourniquet. Similar standard postoperative rehabilitation protocols with early mobilization were used in all cases.

During clinical evaluation, patient demographic data were collected and LLD surveys administered. Patients were asked, before surgery and 3 to 6 weeks, 3 months, 6 months, and 1 year after surgery, if they perceived LLD. A patient who no longer perceived LLD after surgery was no longer followed for this study.

At the preoperative clinic visit and at the 3-month or 6-week postoperative visit, standing mechanical axis radiographs were viewed by 2 of the authors (not the primary surgeons) using PACS (picture archiving and communication system software). The mechanical axis of the operative leg was measured with ImageJ software by taking the angle from the center of the femur to the middle of the ankle joint, with the vertex assigned to the middle of the knee joint.

We used a 2-tailed unpaired t test to determine the relationship of preoperative mechanical axis to perceived LLD (or lack thereof) before surgery. The data were analyzed for separate varus and valgus deformities. Then we determined the relationship of postoperative mechanical axis to perceived LLD (or lack thereof) after surgery. The McNemar test was used to determine the effect of surgery on patients’ LLD perceptions.

To determine the relationship between preoperative-to-postoperative change in mechanical axis and change in LLD perceptions, we divided patients into 4 groups. Group 1 had both preoperative and postoperative perceived LLD, group 2 had no preoperative or postoperative perceived LLD, group 3 had preoperative perceived LLD but no postoperative perceived LLD, and group 4 had postoperative perceived LLD but no preoperative perceived LLD. The absolute value of the difference between preoperative and postoperative mechanical axis was then determined, relative to 180°, to account for changes in varus to valgus deformity before and after surgery and vice versa. Analysis of variance (ANOVA) was used to detect differences between groups. This analysis was then stratified based on BMI and age.

 

Results

Of the 73 enrolled patients, 2 were excluded from results analysis because of inadequate data—one did not complete the postoperative LLD survey, and the other did not have postoperative standing mechanical axis radiographs—leaving 71 patients (27 men, 44 women) with adequate data. Mean (SD) age of all patients was 65 (8.4) years (range, 47-89 years). Mean (SD) BMI was 35.1 (9.9; range, 20.2-74.8).

Of the 71 patients with adequate data, 18 had preoperative perceived LLD and 53 did not; in addition, 7 had postoperative perceived LLD and 64 did not. All 7 patients with postoperative perceived LLD noted resolution of LLD, at a mean of 8.5 weeks (range, 3 weeks-3 months). There was a significant difference between the 18 patients with preoperative perceived LLD and the 7 with postoperative perceived LLD (P = .035, analyzed with the McNemar test).

Table 1 lists the mean preoperative mechanical axis measurements for patients with and without preoperative perceived LLD.

There was no significant difference between the 2 groups (P = .27). There was also no significant difference in preoperative mechanical axis when cases were separated and analyzed as varus and valgus deformities (varus P = .53, valgus P = .20).

Table 2 lists the mean postoperative mechanical axis measurements for patients with and without postoperative perceived LLD.

There was no significant difference between the 2 groups (P = .42). There was also no significant difference in postoperative mechanical axis for separate varus (P = .29) and valgus (P = .52) deformities.

Table 3 lists the mean absolute values of mechanical axis correction (preoperative to postoperative) for the 4 patient groups described in the Methods section.

ANOVA revealed no significant statistical difference in these values among the groups (P = .9229). There were also no significant statistical differences when the groups were stratified by age (40-59.9 years, P = .5973; 60-69.9 years, P = .6263; 70 years or older, P = .3779) or when ANOVA was used to compare the groups’ mean ages (P = .3183). In addition, the 4 groups were not significantly statistically different in BMI: obese (BMI >30; P = .3891) and nonobese (BMI <29.9; P = .9862).

Discussion

In this study, 18 patients (25%) had preoperative perceived LLD, proving that perceived LLD is common in patients who undergo TKA for unilateral osteoarthritis. Surgeons should give their patients a preoperative survey on perceived LLD, as survey responses may inform and influence surgical decisions and strategies.

Of the 18 patients with preoperative perceived LLD, only 1 had postoperative perceived LLD. That perceived LLD decreased after surgery makes sense given the widely accepted notion that actual LLD is common before primary TKA but in most cases is corrected during surgery.^4,5 As LLD correction during surgery is so successful, surgeons should tell their patients with preoperative perceived LLD that in most cases it will be fixed after TKA.

Although the incidence of perceived LLD decreased after TKA (as mentioned earlier), the decrease seemed to be restricted mostly to patients with preoperative perceived LLD, and the underlying LLD was most probably corrected by the surgery. However, surgery introduced perceived LLD in 6 cases, supporting the notion that it is crucial to understand which patients are at higher risk for postoperative perceived LLD and what if any time frame can be expected for resolution in these cases. In our study, all cases of perceived LLD had resolved by a mean follow-up of 8.5 weeks (range, 3 weeks-3 months). This phenomenon of resolution may be attributed to some of the physical, objective LLD corrections that naturally occur throughout the postoperative course,⁴ though psychological factors may also be involved. Our study results suggest patients should be counseled that, though about 10% of patients perceive LLD after primary TKA, the vast majority of perceived LLD cases resolve within 3 months.

One study goal was to determine the relationship between the mechanical axis of the knee and perceived LLD both before and after surgery. There were no significant relationships. This was also true when cases of varus and valgus deformity were analyzed separately.

Another study goal was to determine if a surgical change in the mechanical alignment of the knee would influence preoperative-to-postoperative LLD perceptions. In our analysis, patients were divided into 4 groups based on their preoperative and postoperative LLD perceptions (see Methods section). ANOVA revealed no significant differences in absolute values of mechanical axis correction among the 4 groups. Likewise, there were no correlations between BMI and age and mechanical axis correction among the groups, suggesting LLD perception is unrelated to any of these variables. Ideally, if a relationship between a threshold knee alignment value and perceived LLD existed, surgeons would be able to counsel patients at higher risk for perceived LLD about how their knee alignment may contribute to their perception. Unfortunately, our study results did not show any significant statistical relationships in this regard.

The problem of LLD in patients undergoing TKA is not new, and much research is needed to determine the correlation between perceived versus actual discrepancies, and why they occur. Our study results confirmed that TKA corrects most cases of preoperative perceived LLD but introduces perceived LLD in other cases. Whether preoperative or postoperative LLD is merely perceived or is in fact an actual discrepancy remains to be seen.

One limitation of this study was its lack of leg-length measurements. Although we studied knee alignment specifically, it would have been useful to compare perceived LLD with measured leg lengths, either clinically or radiographically, especially since leg lengths obviously play a role in any perceived LLD. We used mechanical alignment as a surrogate for actual LLD because we hypothesized that alignment may contribute to patients’ perceived discrepancies.

Another limitation was the relatively small sample. Only 24 cases of perceived LLD were analyzed. Given our low rates of perceived LLD (25% before surgery, 10% after surgery), it is difficult to study a large enough TKA group to establish a statistically significant number of cases. Nevertheless, investigators may use larger groups to establish more meaningful relationships.

A third limitation was that alignment was measured on the operative side but not the contralateral side. As we were focusing on perceived discrepancy, contralateral knee alignment may play an important role. Our study involved patients with unilateral osteoarthritis, so it would be reasonable to assume the nonoperative knee was almost neutral in alignment in most cases. However, given that varus/valgus misalignment is a known risk factor for osteoarthritis,⁶ many of our patients with unilateral disease may very well have had preexisting misalignment of both knees. The undetermined alignment of the nonoperative side may be a confounding variable in the relationship between operative knee alignment and perceived LLD.

Fourth, not all patients were surveyed 3 weeks after surgery. Some were first surveyed at 6 weeks, and it is possible there were cases of transient postoperative LLD that resolved before that point. Therefore, our reported incidence of postoperative LLD could have missed some cases. In addition, our mean 8.5-week period for LLD resolution may not have accounted for these resolved cases of transient perceived LLD.

Am J Orthop. 2016;45(7):E429-E433. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.

Leg-length discrepancy (LLD) is common in the general population¹ and particularly in patients with degenerative joint diseases of the hip and knee.² Common complications of LLD include femoral, sciatic, and peroneal nerve palsy; lower back pain; gait abnormalities³; and general dissatisfaction. LLD is a concern for orthopedic surgeons who perform total knee arthroplasty (TKA) because limb lengthening is common after this procedure.^4,5 Surgeons are aware of the limb lengthening that occurs during TKA,^4,5 and studies have confirmed that LLD usually decreases after TKA.^4,5

Despite surgeons’ best efforts, some patients still perceive LLD after surgery, though the incidence of perceived LLD in patients who have had TKA has not been well documented. Aside from actual, objectively measured LLD, there may be other factors that lead patients to perceive LLD. Study results have suggested that preoperative varus–valgus alignment of the knee joint may correlate with how much an operative leg is lengthened after TKA^4,5; however, the outcome investigated was objective LLD measurements, not perceived LLD. Understanding the factors that may influence patients’ ability to perceive LLD would allow surgeons to preoperatively identify patients who are at higher risk for postoperative perceived LLD. This information, along with expected time to resolution of postoperative perceived LLD, would allow surgeons to educate their patients accordingly.

We conducted a study to determine the incidence of perceived LLD before and after primary TKA in patients with unilateral osteoarthritis and to determine the correlation between mechanical axis of the knee and perceived LLD before and after surgery. Given that surgery may correct mechanical axis misalignment, we investigated the correlation between this correction and its ability to change patients’ preoperative and postoperative perceived LLD. We hypothesized that a large correction of mechanical axis would lead patients to perceive LLD after surgery. The relationship of body mass index (BMI) and age to patients’ perceived LLD was also assessed. The incidence and time frame of resolution of postoperative perceived LLD were determined.

Methods

Approval for this study was received from the Institutional Review Board at our institution, Rush University Medical Center in Chicago, Illinois. Seventy-three patients undergoing primary TKA performed by 3 surgeons at 2 institutions between February 2010 and January 2013 were prospectively enrolled. Inclusion criteria were age 18 years to 90 years and primary TKA for unilateral osteoarthritis; exclusion criteria were allergy or intolerance to the study materials, operative treatment of affected joint or its underlying etiology within prior month, previous surgeries (other than arthroscopy) on affected joint, previous surgeries (on unaffected lower extremity) that may influence preoperative and postoperative leg lengths, and any substance abuse or dependence within the past 6 months. Patients provided written informed consent for total knee arthroplasty.

All surgeries were performed by Dr. Levine, Dr. Della Valle, and Dr. Sporer using the medial parapatellar or midvastus approach with tourniquet. Similar standard postoperative rehabilitation protocols with early mobilization were used in all cases.

During clinical evaluation, patient demographic data were collected and LLD surveys administered. Patients were asked, before surgery and 3 to 6 weeks, 3 months, 6 months, and 1 year after surgery, if they perceived LLD. A patient who no longer perceived LLD after surgery was no longer followed for this study.

At the preoperative clinic visit and at the 3-month or 6-week postoperative visit, standing mechanical axis radiographs were viewed by 2 of the authors (not the primary surgeons) using PACS (picture archiving and communication system software). The mechanical axis of the operative leg was measured with ImageJ software by taking the angle from the center of the femur to the middle of the ankle joint, with the vertex assigned to the middle of the knee joint.

We used a 2-tailed unpaired t test to determine the relationship of preoperative mechanical axis to perceived LLD (or lack thereof) before surgery. The data were analyzed for separate varus and valgus deformities. Then we determined the relationship of postoperative mechanical axis to perceived LLD (or lack thereof) after surgery. The McNemar test was used to determine the effect of surgery on patients’ LLD perceptions.

To determine the relationship between preoperative-to-postoperative change in mechanical axis and change in LLD perceptions, we divided patients into 4 groups. Group 1 had both preoperative and postoperative perceived LLD, group 2 had no preoperative or postoperative perceived LLD, group 3 had preoperative perceived LLD but no postoperative perceived LLD, and group 4 had postoperative perceived LLD but no preoperative perceived LLD. The absolute value of the difference between preoperative and postoperative mechanical axis was then determined, relative to 180°, to account for changes in varus to valgus deformity before and after surgery and vice versa. Analysis of variance (ANOVA) was used to detect differences between groups. This analysis was then stratified based on BMI and age.

 

Results

Of the 73 enrolled patients, 2 were excluded from results analysis because of inadequate data—one did not complete the postoperative LLD survey, and the other did not have postoperative standing mechanical axis radiographs—leaving 71 patients (27 men, 44 women) with adequate data. Mean (SD) age of all patients was 65 (8.4) years (range, 47-89 years). Mean (SD) BMI was 35.1 (9.9; range, 20.2-74.8).

Of the 71 patients with adequate data, 18 had preoperative perceived LLD and 53 did not; in addition, 7 had postoperative perceived LLD and 64 did not. All 7 patients with postoperative perceived LLD noted resolution of LLD, at a mean of 8.5 weeks (range, 3 weeks-3 months). There was a significant difference between the 18 patients with preoperative perceived LLD and the 7 with postoperative perceived LLD (P = .035, analyzed with the McNemar test).

Table 1 lists the mean preoperative mechanical axis measurements for patients with and without preoperative perceived LLD.

There was no significant difference between the 2 groups (P = .27). There was also no significant difference in preoperative mechanical axis when cases were separated and analyzed as varus and valgus deformities (varus P = .53, valgus P = .20).

Table 2 lists the mean postoperative mechanical axis measurements for patients with and without postoperative perceived LLD.

There was no significant difference between the 2 groups (P = .42). There was also no significant difference in postoperative mechanical axis for separate varus (P = .29) and valgus (P = .52) deformities.

Table 3 lists the mean absolute values of mechanical axis correction (preoperative to postoperative) for the 4 patient groups described in the Methods section.

ANOVA revealed no significant statistical difference in these values among the groups (P = .9229). There were also no significant statistical differences when the groups were stratified by age (40-59.9 years, P = .5973; 60-69.9 years, P = .6263; 70 years or older, P = .3779) or when ANOVA was used to compare the groups’ mean ages (P = .3183). In addition, the 4 groups were not significantly statistically different in BMI: obese (BMI >30; P = .3891) and nonobese (BMI <29.9; P = .9862).

Discussion

In this study, 18 patients (25%) had preoperative perceived LLD, proving that perceived LLD is common in patients who undergo TKA for unilateral osteoarthritis. Surgeons should give their patients a preoperative survey on perceived LLD, as survey responses may inform and influence surgical decisions and strategies.

Of the 18 patients with preoperative perceived LLD, only 1 had postoperative perceived LLD. That perceived LLD decreased after surgery makes sense given the widely accepted notion that actual LLD is common before primary TKA but in most cases is corrected during surgery.^4,5 As LLD correction during surgery is so successful, surgeons should tell their patients with preoperative perceived LLD that in most cases it will be fixed after TKA.

Although the incidence of perceived LLD decreased after TKA (as mentioned earlier), the decrease seemed to be restricted mostly to patients with preoperative perceived LLD, and the underlying LLD was most probably corrected by the surgery. However, surgery introduced perceived LLD in 6 cases, supporting the notion that it is crucial to understand which patients are at higher risk for postoperative perceived LLD and what if any time frame can be expected for resolution in these cases. In our study, all cases of perceived LLD had resolved by a mean follow-up of 8.5 weeks (range, 3 weeks-3 months). This phenomenon of resolution may be attributed to some of the physical, objective LLD corrections that naturally occur throughout the postoperative course,⁴ though psychological factors may also be involved. Our study results suggest patients should be counseled that, though about 10% of patients perceive LLD after primary TKA, the vast majority of perceived LLD cases resolve within 3 months.

One study goal was to determine the relationship between the mechanical axis of the knee and perceived LLD both before and after surgery. There were no significant relationships. This was also true when cases of varus and valgus deformity were analyzed separately.

Another study goal was to determine if a surgical change in the mechanical alignment of the knee would influence preoperative-to-postoperative LLD perceptions. In our analysis, patients were divided into 4 groups based on their preoperative and postoperative LLD perceptions (see Methods section). ANOVA revealed no significant differences in absolute values of mechanical axis correction among the 4 groups. Likewise, there were no correlations between BMI and age and mechanical axis correction among the groups, suggesting LLD perception is unrelated to any of these variables. Ideally, if a relationship between a threshold knee alignment value and perceived LLD existed, surgeons would be able to counsel patients at higher risk for perceived LLD about how their knee alignment may contribute to their perception. Unfortunately, our study results did not show any significant statistical relationships in this regard.

The problem of LLD in patients undergoing TKA is not new, and much research is needed to determine the correlation between perceived versus actual discrepancies, and why they occur. Our study results confirmed that TKA corrects most cases of preoperative perceived LLD but introduces perceived LLD in other cases. Whether preoperative or postoperative LLD is merely perceived or is in fact an actual discrepancy remains to be seen.

One limitation of this study was its lack of leg-length measurements. Although we studied knee alignment specifically, it would have been useful to compare perceived LLD with measured leg lengths, either clinically or radiographically, especially since leg lengths obviously play a role in any perceived LLD. We used mechanical alignment as a surrogate for actual LLD because we hypothesized that alignment may contribute to patients’ perceived discrepancies.

Another limitation was the relatively small sample. Only 24 cases of perceived LLD were analyzed. Given our low rates of perceived LLD (25% before surgery, 10% after surgery), it is difficult to study a large enough TKA group to establish a statistically significant number of cases. Nevertheless, investigators may use larger groups to establish more meaningful relationships.

A third limitation was that alignment was measured on the operative side but not the contralateral side. As we were focusing on perceived discrepancy, contralateral knee alignment may play an important role. Our study involved patients with unilateral osteoarthritis, so it would be reasonable to assume the nonoperative knee was almost neutral in alignment in most cases. However, given that varus/valgus misalignment is a known risk factor for osteoarthritis,⁶ many of our patients with unilateral disease may very well have had preexisting misalignment of both knees. The undetermined alignment of the nonoperative side may be a confounding variable in the relationship between operative knee alignment and perceived LLD.

Fourth, not all patients were surveyed 3 weeks after surgery. Some were first surveyed at 6 weeks, and it is possible there were cases of transient postoperative LLD that resolved before that point. Therefore, our reported incidence of postoperative LLD could have missed some cases. In addition, our mean 8.5-week period for LLD resolution may not have accounted for these resolved cases of transient perceived LLD.

Am J Orthop. 2016;45(7):E429-E433. Copyright Frontline Medical Communications Inc. 2016. All rights reserved.