2025 ISAKOS Biennial Congress ePoster
Long-Term Hip Arthroscopy Survivorship Can Be Predicted By A Lateral/Medial Joint Space Ratio <1
Jonathan S. Lee, BA, Boston UNITED STATES
Stephen M. Gillinov, AB, New Haven, CT UNITED STATES
Bilal Siddiq, BS, Boston UNITED STATES
Kieran Sinclair Dowley, BA, Boston, Massachusetts UNITED STATES
Nathan J. Cherian, MD, Somerville, Massachusetts UNITED STATES
Christopher T. Eberlin, BS, Boston, MA UNITED STATES
Jeffrey S. Mun, BA UNITED STATES
Brandon J. Allen , BA, Boston , Massachusetts UNITED STATES
Scott D. Martin, MD, Boston, MA UNITED STATES
Massachusetts General Hospital, Boston, MA, UNITED STATES
FDA Status Not Applicable
Summary
Patients with a lateral/medial joint space ratio <1 had a 139% higher adjusted-risk of converting to total hip arthroplasty (THA) when assessing 15-year THA-free survivorship.
Abstract
PURPOSE/HYPOTHESIS: To investigate if a pre-operative lateral/medial femoroacetabular joint space ratio (LM ratio) <1 predicts 15-year THA-free survivorship following primary hip arthroscopy for symptomatic acetabular labral tears. We hypothesized that patients with a LM <1 had a significantly increased long-term risk of converting to THA.
Methods
This study queried patients ≥18 years old who underwent hip arthroscopy for symptomatic acetabular labral tears secondary to FAI. Femoroacetabular joint space width (JSW) of the ipsilateral hip was collected using a computer-assisted, semi-automated method of assessing anteroposterior (AP) radiographs. Measurements were performed at 3 fixed locations per hip at 10° [lateral], 30° [central], and 50° [medial] with respect to a polar coordinate system. Patients with minimum 5-year follow-up, Tönnis grade 0 or 1, and JSW >2 mm were included. Lateral/medial joint space ratio was calculated by dividing lateral JSW by medial JSW. The study population was stratified into LMLow and LMHigh cohorts according to a LM ratio <1 or ≥1, respectively. 15-year THA-free survivorship was assessed using a Kaplan-Meier survival curve analyzed by log-rank test. A weighted Cox regression adjusting for baseline demographics and intraoperative findings was performed to identify independent adjusted-risk factors for converting to THA.
Results
Overall, 256 patients (LMLow: 95 [37.1%] vs LMHigh: 161 [62.9%]) met inclusion criteria. The were no differences between LM cohorts for age (LMLow: 39.0 ± 11.3 vs. LMHigh: 37.6 ± 11.6 years; P=.341) and BMI (LMLow: 25.6 ± 4.2 vs. LMHigh: 25.8 ± 4.3 kg/m2; P=.698). Within 15 years, a significantly greater proportion of LMLow patients underwent THA (24 [25.26%] vs 11 [6.83%]; P<.0001). By weighted cox regression controlling for age, sex, BMI, FAI type, Outerbridge grade, Beck classification of transition zone cartilage damage, and labral treatment (repair vs. debridement), having a LM <1 increased the 15-year risk of converting to THA by 139% (P=.024).
Conclusions
Patients with a LM <1 had a 139% higher adjusted-risk of converting to THA when assessing 15-year THA-free survivorship. These findings suggest that reduced JSW at the edge-loading area of the lateral acetabulum may be an important indicator for progressive osteoarthritis and long-term conversion to THA.