Paper #8 - ISHA Annual Scientific Meeting 2016

Learning Curve for Hip Arthroscopy Steeper than Expected

Nabil Mehta, BSE, New York, NY UNITED STATES
Peter Chamberlin, BA, New York, NY UNITED STATES
Chisa Hidaka, MD, New York, NY UNITED STATES
Yile Ge, MSE, New York, NY UNITED STATES
Ting Jung Pan, MPH, New York, NY UNITED STATES
Danyal H. Nawabi, MD, FRCS(Orth), New York, NY UNITED STATES
Stephen Lyman, PhD, New York, NY UNITED STATES

Hospital for Special Surgery, New York, NY, UNITED STATES

FDA Status Cleared

Summary: Stratum specific likelihood ratio analysis of 8,041 hip arthroscopies in New York State found 4 strata of surgeon career volume associated with significantly different risks of additional surgery after hip arthroscopy. Surgeons with hip-specific fellowships have lower risk of additional surgery earlier in their career and learn faster than those without.

Abstract:
Background: While increasingly recognized as an effective procedure for the treatment of femoroacetabular impingement and related hip disorders, hip arthroscopy is considered a technically challenging procedure whose learning curve is not well defined. The purpose of this study was to define the learning curve through which surgeons become proficient at hip arthroscopy, as demonstrated by decreased additional hip surgeries after the procedure. Methods: We identified hip arthroscopy procedures performed by individual surgeons through the New York State SPARCS database between 2003-2012 and followed those cases over time for additional hip surgery (revision hip arthroscopy, total hip arthroplasty, or hip resurfacing) within five years of the original procedure. Career volume was calculated for each case as the number of hip arthroscopy procedures the surgeon had performed before the index procedure. Volume strata were identified by applying stratum specific likelihood ratio (SSLR) analysis of a receiver operating characteristic (ROC) curve. A Cox proportional hazards model was used to measure the effect of surgeon career volume on risk of additional hip surgery adjusting for patient characteristics: age, sex, race/ethnicity, insurance type, and concurrent diagnosis of hip osteoarthritis. An interaction variable was created between career volume and hip-specific fellowship, defined as hip preservation or hip arthroscopy. Results: Amongst 8,041 hip arthroscopies performed by 251 surgeons, 989 (12.3%) underwent additional hip surgery within five years. We identified 4 strata of surgeon career volume associated with distinct frequencies of additional surgery after hip arthroscopy: Cases in the lowest volume stratum (0-97) had the highest frequency of additional surgery (15.4%). Frequencies declined for cases in the middle (98-388), high (389-518) and highest (>519) strata (13.8%, 10.1% and 2.6% respectively). Risk of additional surgery in each strata compared to the highest volume strata was lower for surgeons with hip-specific fellowship vs. those without, and also decreased faster (Hip-specific fellowship: HR[95%CI] low:3.06[1.70,5.53] p<0.001, medium:2.81[1.59,4.95] p<0.001, high:1.67[0.68,4.10] p=0.2633; without hip-specific fellowships: low:3.96[2.36,6.66], medium:4.53[2.68,7.64], high:3.89[2.19,6.91]; p<0.0001 for all). Increased risk was also detected in patients =30 years old vs. those 29 or younger (30-39: 1.56[1.25, 1.95], 40-49: 2.38[1.94, 2.91], 50+: 3.27[2.66, 4.02]; p<0.0001 for all), those with a diagnosis of hip osteoarthritis (2.11[1.81, 2.45], p<0.0001), and those with Medicaid vs. private insurance (1.46[1.04, 2.06], p=0.029). Risk of additional hip surgery was lower in Black (0.66[0.46, 0.94], p=0.022) and other race (0.76[0.63, 0.93], p=0.007) compared to White patients. Risk of additional hip surgery was not affected by sex. Conclusion: The learning curve for hip arthroscopy was unexpectedly high. Surgeons with hip-specific fellowships have lower risk of additional surgery earlier in their career and learn faster than those without. They reached the lowest statistically significant risk of additional surgery at 98 career cases, while for surgeons without hip-specific fellowship, risk of additional surgery did not significantly decrease until a surgeon reached 389 career cases.