Complications and Risk Factors for Morbidity in Elective Hip Arthroscopy: A Review of 1325 Cases

Take-Home Points

• Using the NSQIP database, the authors report that the overall complication rate was 1.21% after hip arthroscopy.
• The most common complications cited were bleeding requiring transfusion (0.45%), return to OR (0.23%), superficial infection (0.23%), and thrombophlebitis (0.15).
• Most common 10CPT code was arthroscopic débridement in 50% of cases, reflecting the types of cases being performed in the time period.
• FAI codes were less common in this database–labral repair in 24%, femoral osteochondroplasty in 16%, and acetabuloplasty in 9%.
• Use caution in patients over age 65 years as this appears to be a risk factor for morbidity.

Hip arthroscopy is a well-described method for treating a number of pathologies.^1-3 Surgical indications are wide-ranging and include femoral acetabular impingement (FAI), labral tears, loose bodies, osteochondral injuries, ruptured ligamentum teres, and synovitis, as well as extra-articular injuries, including hip abductor tears and sciatic nerve entrapment.^2,4-6 Authors have suggested that the advantages of hip arthroscopy over open procedures include less traumatic access to the hip joint and faster recovery,^7,8 and hip arthroscopy has been found cost-effective in select groups of patients.⁹

Overall complications have been reported in 1% to 20% of hip arthroscopy patients,^6,8,10,11 and a meta-analysis identified an overall complication rate of 4%.⁸ Complications include iatrogenic chondrolabral injury, nerve injury, superficial surgical-site infection, deep vein thrombosis (DVT), instrument failure, portal wound bleeding, soft-tissue injury, and intra-abdominal fluid extravasation.^6,8,10-13 Rates of major complications are relatively low, 0.3% to 0.58%, according to several recent systematic reviews.^8,12 Given the lack of universally accepted definitions, reports of minor complications (eg, iatrogenic chondrolabral injury, neuropraxia) in hip arthroscopy vary widely.⁸ Furthermore, many of the series with high complication rates represent early experience with the technique, and later authors suggested that complications should decrease with improvements in technique and technology.^12,14,15The literature is lacking in reports of risk factors for patient morbidity and large multi-institutional cohorts in the setting of hip arthroscopy. We conducted a study of elective hip arthroscopy patients to determine type and incidence of complications and rates of and risk factors for minor and major morbidity.

Materials and Methods

This retrospective study was deemed compliant with HIPAA (Health Insurance Portability and Accountability Act of 1996) and exempt from the need for Institutional Review Board approval. In the National Surgical Quality Improvement Program (NSQIP), academic and private medical institutions prospectively collect patient preoperative and operative data as well as 30-day outcome data from more than 500 hospitals throughout the United States.^16-21 Surgical clinical reviewers, who are responsible for data acquisition, prospectively collect morbidity data for 30 days after surgery through a chart review of patient progress notes, operative notes, and follow-up clinic visits. Patients may be contacted by a surgical clinical reviewer if they have not had a clinic visit within 30 days after a procedure to verify the presence or absence of complications or admissions at outside institutions, and in this way even outpatient complications should be captured. If the medical record is unclear, the reviewer may also contact the surgeon directly. In addition, NSQIP data are routinely audited; the interobserver disagreement rate is 1.56%.²²

We used Current Procedural Terminology (CPT) billing codes to retrospectively survey the NSQIP database for hip arthroscopies performed between 2006 and 2013. Excluding cases of compromised surgical wounds, emergent surgeries, surgeries involving fracture, hip dislocations, preoperative sepsis, septic joints, and osteomyelitis, we identified 1325 cases with CPT codes 29861 (hip arthroscopy), 29862 (arthroscopic hip débridement, shaving), 29914 (arthroscopic femoroplasty), 29915 (arthroscopic acetabuloplasty), and 29916 (arthroscopic labral repair). Postoperative outcomes were categorized as major morbidity or mortality, minor morbidity, and any complication. A major complication was a systemic life-threatening event or a substantial threat to a vital organ, whereas a minor complication did not pose a major systemic threat and was localized to the operative extremity (previously used definitions^23,24). We have used similar methods to report the rates of and risk factors for complications of knee arthroscopy, shoulder arthroscopy, and total shoulder arthroplasty.^16,20,21 For any-complication outcomes, we included both major and minor morbidities, and mortality. NSQIP applies strict definitions (listed in its user file¹⁷) to patient comorbidities and complications. Data points collected included patient demographics, medical comorbidities, laboratory values, and surgical characteristics.

Initially, we performed a univariate analysis that considered age, sex, race, body mass index, current alcohol abuse, current smoking status, recent weight loss, dyspnea, chronic obstructive pulmonary disease, CPT code, congestive heart failure, hypertension, diabetes, peripheral vascular disease, esophageal varices, disseminated cancer, steroid use, bleeding disorder, dialysis, chemotherapy within previous 30 days, radiation therapy within previous 90 days, operation within previous 30 days, American Society of Anesthesiologists class, operative time, resident involvement, and patient functional status. We also included mean preoperative sodium, blood urea nitrogen, and albumin levels; white blood cell count; hematocrit; platelet count; and international normalized ratio. The analysis revealed unadjusted differences between patients with and without complications (t test was used for continuous variables, χ² test for categorical variables). Any variable with P < .2 in the univariate analysis and more than 80% complete data was considered fit for our multivariate model. We controlled for confounders by performing a multivariate logistic regression analysis. Three separate analyses were performed; the outcome variables were major morbidity or mortality, minor morbidity, and any complication. P < .05 was used for statistical significance across all models. We used SAS Version 9.3 (SAS Institute) for statistical analysis. Model quality was evaluated for calibration (Hosmer-Lemeshow test) and discrimination (C statistics). The calibration test yielded a modified χ² statistic, and P > .05 indicated the model was appropriate and fit the data well. Good discrimination is commonly reported to be between 0.65 and 0.85.