X-Ray Analysis Predicts Knee Osteoarthritis Progression

BRUSSELS – Analysis of plain x-ray images of knee joints from 60 patients with osteoarthritis confirmed that a novel method for assessing bone trabecular structure adjacent to knee joints provides a reliable prediction of future disease progression.

Assessment of bone trabecular integrity by fractal signature analysis “provides an osteoarthritis imaging biomarker that is a prognostic marker of knee osteoarthritis progression,” Dr. Virginia Byers Kraus said at the annual World Congress on Osteoarthritis.

Baseline bone trabecular integrity predicted roughly 85% of the change in joint space area during 2 years of follow-up in patients with osteoarthritis (OA). The new study, which used x-rays from 60 patients with OA and 67 controls, is the second report to document the prognostic accuracy of fractal signature analysis of bone trabecular integrity in OA patients. The first report, also from Dr. Kraus and her associates, came out last year, and involved 138 OA patients who were followed for 3 years (Arthritis Rheum. 2009;60:3711-22).

“The next step is to compare fractal signature analysis head to head with MRI and look at its ability to predict MRI changes” in OA patients, and “its ability to identify OA in the preradiographic stage,” Dr. Kraus said in an interview.

Fractal signature analysis of bone trabecular integrity using x-ray images “gives you the ability to more fully phenotype patients than we’ve been able to, and it is less costly than MRI,” said Dr. Kraus, a rheumatologist and professor of medicine at Duke University in Durham, N.C. “It’s very promising for identifying patients at high risk for progression in [an intervention] trial, and possibly to screen patients in the clinic.”

Fractal signature analysis evaluates the complexity of detail of a two-dimensional image. Researchers first reported using fractal signature analysis in 1991 to assess bone architecture in radiographs of OA joints. Past studies also successfully used the method to assess osteoporosis and arthritis of the spine, hip, wrists, hands, and knees before and after surgery. Fractal signature analysis has the major advantage of not being very sensitive to image-acquisition quality.

Although fractal signature analysis involves a complex statistical analysis of x-ray image data of bone structure adjacent to a patient’s knee joint, Dr. Kraus and her associates incorporated that analysis into “KneeAnalyzer” software developed by Optasia Medical, a British company. Now that the software exists, “it is easy to use. It’s just a tool to get at bone trabecular integrity. I think it can easily be widely adopted,” she said.

The new study used data collected in a non–therapeutic methods trial sponsored by Pfizer Inc. The data set included 60 women with knee OA, an average age of 58 years, and an average body mass index of 35.6 kg/m2. (All participants in this arm of the study had a BMI of at least 30.) The 67 women controls had an average age of 55 years, all had a BMI of 28 or less, and all had no knee symptoms, no radiographic signs of knee OA, and no history of knee fracture, surgery, or disease.

The researchers assessed bone trabecular integrity using fractal signature analysis on radiographs taken at baseline, and after 12 and 24 months. The results showed that baseline measurements in the vertical dimension of bone trabecular integrity predicted changes in joint space area at 12 and 24 months, and in joint space width at 24 months. Baseline measures in the horizontal dimension were not predictive. The predicted changes based on baseline bone trabecular integrity accounted for 85%-87% of the actual change in joint space area over 24 months, Dr. Kraus reported at the congress, which was organized by the Osteoarthritis Research Society International.

Analysis of baseline and follow-up measures in the control subjects allowed the researchers to attribute progression in patients to an OA-specific process and not as the result of aging.

Dr. Kraus said that she had no relevant disclosures. One coauthor is an employee of Optasia Medical, and Optasia provided the software used for the radiograph analyses. Another coauthor is an employee of Pfizer, and Pfizer supplied the database used in the study.

BRUSSELS – Analysis of plain x-ray images of knee joints from 60 patients with osteoarthritis confirmed that a novel method for assessing bone trabecular structure adjacent to knee joints provides a reliable prediction of future disease progression.

Assessment of bone trabecular integrity by fractal signature analysis “provides an osteoarthritis imaging biomarker that is a prognostic marker of knee osteoarthritis progression,” Dr. Virginia Byers Kraus said at the annual World Congress on Osteoarthritis.

Baseline bone trabecular integrity predicted roughly 85% of the change in joint space area during 2 years of follow-up in patients with osteoarthritis (OA). The new study, which used x-rays from 60 patients with OA and 67 controls, is the second report to document the prognostic accuracy of fractal signature analysis of bone trabecular integrity in OA patients. The first report, also from Dr. Kraus and her associates, came out last year, and involved 138 OA patients who were followed for 3 years (Arthritis Rheum. 2009;60:3711-22).

“The next step is to compare fractal signature analysis head to head with MRI and look at its ability to predict MRI changes” in OA patients, and “its ability to identify OA in the preradiographic stage,” Dr. Kraus said in an interview.

Fractal signature analysis of bone trabecular integrity using x-ray images “gives you the ability to more fully phenotype patients than we’ve been able to, and it is less costly than MRI,” said Dr. Kraus, a rheumatologist and professor of medicine at Duke University in Durham, N.C. “It’s very promising for identifying patients at high risk for progression in [an intervention] trial, and possibly to screen patients in the clinic.”

Fractal signature analysis evaluates the complexity of detail of a two-dimensional image. Researchers first reported using fractal signature analysis in 1991 to assess bone architecture in radiographs of OA joints. Past studies also successfully used the method to assess osteoporosis and arthritis of the spine, hip, wrists, hands, and knees before and after surgery. Fractal signature analysis has the major advantage of not being very sensitive to image-acquisition quality.

Although fractal signature analysis involves a complex statistical analysis of x-ray image data of bone structure adjacent to a patient’s knee joint, Dr. Kraus and her associates incorporated that analysis into “KneeAnalyzer” software developed by Optasia Medical, a British company. Now that the software exists, “it is easy to use. It’s just a tool to get at bone trabecular integrity. I think it can easily be widely adopted,” she said.

The new study used data collected in a non–therapeutic methods trial sponsored by Pfizer Inc. The data set included 60 women with knee OA, an average age of 58 years, and an average body mass index of 35.6 kg/m2. (All participants in this arm of the study had a BMI of at least 30.) The 67 women controls had an average age of 55 years, all had a BMI of 28 or less, and all had no knee symptoms, no radiographic signs of knee OA, and no history of knee fracture, surgery, or disease.

The researchers assessed bone trabecular integrity using fractal signature analysis on radiographs taken at baseline, and after 12 and 24 months. The results showed that baseline measurements in the vertical dimension of bone trabecular integrity predicted changes in joint space area at 12 and 24 months, and in joint space width at 24 months. Baseline measures in the horizontal dimension were not predictive. The predicted changes based on baseline bone trabecular integrity accounted for 85%-87% of the actual change in joint space area over 24 months, Dr. Kraus reported at the congress, which was organized by the Osteoarthritis Research Society International.

Analysis of baseline and follow-up measures in the control subjects allowed the researchers to attribute progression in patients to an OA-specific process and not as the result of aging.

Dr. Kraus said that she had no relevant disclosures. One coauthor is an employee of Optasia Medical, and Optasia provided the software used for the radiograph analyses. Another coauthor is an employee of Pfizer, and Pfizer supplied the database used in the study.

BRUSSELS – Analysis of plain x-ray images of knee joints from 60 patients with osteoarthritis confirmed that a novel method for assessing bone trabecular structure adjacent to knee joints provides a reliable prediction of future disease progression.

Assessment of bone trabecular integrity by fractal signature analysis “provides an osteoarthritis imaging biomarker that is a prognostic marker of knee osteoarthritis progression,” Dr. Virginia Byers Kraus said at the annual World Congress on Osteoarthritis.

Baseline bone trabecular integrity predicted roughly 85% of the change in joint space area during 2 years of follow-up in patients with osteoarthritis (OA). The new study, which used x-rays from 60 patients with OA and 67 controls, is the second report to document the prognostic accuracy of fractal signature analysis of bone trabecular integrity in OA patients. The first report, also from Dr. Kraus and her associates, came out last year, and involved 138 OA patients who were followed for 3 years (Arthritis Rheum. 2009;60:3711-22).

“The next step is to compare fractal signature analysis head to head with MRI and look at its ability to predict MRI changes” in OA patients, and “its ability to identify OA in the preradiographic stage,” Dr. Kraus said in an interview.

Fractal signature analysis of bone trabecular integrity using x-ray images “gives you the ability to more fully phenotype patients than we’ve been able to, and it is less costly than MRI,” said Dr. Kraus, a rheumatologist and professor of medicine at Duke University in Durham, N.C. “It’s very promising for identifying patients at high risk for progression in [an intervention] trial, and possibly to screen patients in the clinic.”

Fractal signature analysis evaluates the complexity of detail of a two-dimensional image. Researchers first reported using fractal signature analysis in 1991 to assess bone architecture in radiographs of OA joints. Past studies also successfully used the method to assess osteoporosis and arthritis of the spine, hip, wrists, hands, and knees before and after surgery. Fractal signature analysis has the major advantage of not being very sensitive to image-acquisition quality.

Although fractal signature analysis involves a complex statistical analysis of x-ray image data of bone structure adjacent to a patient’s knee joint, Dr. Kraus and her associates incorporated that analysis into “KneeAnalyzer” software developed by Optasia Medical, a British company. Now that the software exists, “it is easy to use. It’s just a tool to get at bone trabecular integrity. I think it can easily be widely adopted,” she said.

The new study used data collected in a non–therapeutic methods trial sponsored by Pfizer Inc. The data set included 60 women with knee OA, an average age of 58 years, and an average body mass index of 35.6 kg/m2. (All participants in this arm of the study had a BMI of at least 30.) The 67 women controls had an average age of 55 years, all had a BMI of 28 or less, and all had no knee symptoms, no radiographic signs of knee OA, and no history of knee fracture, surgery, or disease.

The researchers assessed bone trabecular integrity using fractal signature analysis on radiographs taken at baseline, and after 12 and 24 months. The results showed that baseline measurements in the vertical dimension of bone trabecular integrity predicted changes in joint space area at 12 and 24 months, and in joint space width at 24 months. Baseline measures in the horizontal dimension were not predictive. The predicted changes based on baseline bone trabecular integrity accounted for 85%-87% of the actual change in joint space area over 24 months, Dr. Kraus reported at the congress, which was organized by the Osteoarthritis Research Society International.

Analysis of baseline and follow-up measures in the control subjects allowed the researchers to attribute progression in patients to an OA-specific process and not as the result of aging.

Dr. Kraus said that she had no relevant disclosures. One coauthor is an employee of Optasia Medical, and Optasia provided the software used for the radiograph analyses. Another coauthor is an employee of Pfizer, and Pfizer supplied the database used in the study.