Pre-operative Predictors of Return to High Functional Status after Hip Arthroscopy for Femoroacetabular Impingement at 2-year Minimum Follow-up

OBJECTIVES: Pre-operative predictors of high functional level at two years following hip arthroscopy are unclear. We hypothesized that smoking status, comorbid disease (hypertension, diabetes, mental health diagnoses, prior surgeries, and spine pathology) would negatively affect outcomes at two-year follow-up while younger age, decreased body mass index (BMI), increased physical activity and shorter preoperative symptom duration would be able to predict outcomes after hip arthroscopy for femoroacetabular impingement (FAI). METHODS: A prospectively collected registry was analyzed for all patients treated for FAI from 2012 to 2015. All patients had a minimum of 2-year follow-up with patient reported outcomes [PROs, including modified Harris Hip Score (mHHS), Hip Outcome Score (HOS)-Activities of Daily Living (ADL), HOS-Sport Specific (HOS-SS), Visual Analog Score (VAS)-Pain and satisfaction. Inclusion criteria were skeletally mature patients at the time of arthroscopy, signs and symptoms consistent with a diagnosis of FAI. Individuals with prior hip surgery, inflammatory arthropathy, and/or advanced osteoarthritis were excluded. Univariate and correlation analyses were performed to identify significant association and multivariate logistic regression analysis was used to identify significant predictors. Significance was set at α ≤ 0.05. RESULTS: Of 1042 qualifying patients, 830 completed 2-year minimum follow-up (80%); mean age and body mass index (BMI) were 33.6±12.8 years and 25.4±11.3 respectively. The majority of patients were female (549, 66.1%), non-smokers (741, 89.3%), who participated in regular recreational sports (623, 75%). One-third (278, 33.5%) experienced preoperative symptoms longer than two-years while 157 (18.9%) experienced symptoms for one-to-two years, with 265 (31.9%) for 4-to-12 months, and 108 (13%) less than 4 months. Mean alpha angle and lateral center edge angle were 61.2±10.1 and 33.1±7.02, respectively. All patients demonstrated significant improvements in PROs following surgery: HOS-ADL (65.20±0.72 to 86.54±0.61; p<0.0001), HOS-SS (42.84±0.89 to 73.98±1.0; p<0.0001), and mHHS (57.4±0.58 to79.92±0.68; p<0.0001). In addition, VAS Pain was significantly decreased from 53.35±1.3 to 19.44±0.86 (p=0.032) with high two-year satisfaction at 81.11±28.28. Regression analysis identified the strongest predictors for high functioning outcomes in the HOS-SS were patients without a history of a mental health diagnoses (anxiety or depression; importance 0.29, p<0.0001) followed by younger age (importance 0.18; p<0.0001). Predictors for improved two-year HOS-ADL outcomes included shorter duration of symptoms (importance 0.22; p<0.0001) and decreased BMI (importance 0.164; p=0.001). Predictors for an improved mHHS included no pre-operative narcotic use (importance 0.19; p=0.001) and no history of a mental health diagnoses (importance 0.18; p=0.001). Predictors of HOS-ADL and mHHS were also significant predictors of a greater HOS-SS score (p=0.001 for all). CONCLUSION: Our results support the hypothesis that patients with mental health diagnoses, increased age and BMI, as well as prolonged preoperative symptom duration are predictors for inferior post-operative functional status at mid-term follow-up. Our results suggest that there are both modifiable and non-modifiable pre-operative factors that have the potential to predict a return to high functional status after hip arthroscopy for FAI.