Midterm Outcomes in Patients Aged 40 Years and Older With Borderline Dysplasia After Hip Arthroscopy for Femoroacetabular Impingement: A Propensity-Matched Analysis

Abstract

Background: Age has been shown to play a role in patient outcomes after hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS), but little is known regarding this relationship in the population with borderline dysplasia.

Purpose: To compare patient outcomes and reoperation rates in patients aged ≥40 years and <40 years with borderline hip dysplasia (BHD) undergoing hip arthroscopy for FAIS at 2- and 5-year follow-up.

Study design: Cohort study; Level of evidence, 3.

Methods: Patient-reported outcomes (PROs) were acquired preoperatively and at 2 and 5 years postoperatively for patients undergoing surgery between January 2012 and June 2019. PROs included the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale (HOS-SS), modified Harris Hip Score, and visual analog scale for pain and satisfaction. Clinically significant outcomes included the minimal clinically important difference and Patient Acceptable Symptom State (PASS). Patients diagnosed with BHD (lateral central-edge angle, 18°-25°) were stratified into cohorts ≥40 and <40 years old. Older patients were propensity matched 1:1 to younger patients controlling for sex, body mass index (BMI), and acetabular cartilage grade. PROs, clinically significant outcomes, and survivorship were compared between groups.

Results: Ninety-three patients aged ≥40 years with BHD (mean ± SD age, 48.4 ± 5.7 years; 68.8% female; BMI, 26.6 ± 5.3 kg/m²) were successfully matched to 93 patients aged <40 years with BHD (age, 26.8 ± 7.6 years; 76.3% female; BMI, 25.9 ± 5.3 kg/m²). Older patients had lower rates of weekly physical activity as compared with younger patients (P < .001). Older patients with BHD had significantly lower HOS-SS scores than younger patients preoperatively (P = .021) and at 5 years postoperatively (P = .040). However, there were no differences in improvement of any PRO from presurgery to 5-year follow-up between groups. Older patients had similar achievements of the minimal clinically important difference (P > .188) but achieved the PASS at a significantly lower rate for the HOS-SS (61.1% vs 79.7%; P = .024). Older patients also underwent conversion to total hip arthroplasty at a significantly higher rate (12.8% vs 1.4%; P = .010) when compared with younger patients, with a mean conversion time of 4.58 years.

Conclusion: This study concludes that patients with BHD aged ≥40 years treated with contemporary hip arthroscopy for FAIS achieved similar function, pain, and satisfaction at 5-year follow-up but worse sports function and sports-related PASS achievement when compared with patients with BHD aged <40 years. Furthermore, while patients ≥40 years old had a higher rate of total hip arthroplasty conversion, they demonstrated similar overall reoperation rates as compared with younger patients at 5 years.

Keywords: borderline hip dysplasia; comparative cohort; hip arthroscopy; patient outcomes.