moment. Dynamic MRI was performed with the knee at rest and with increasing varus forces according to the patient’s specific adduction moment. Medial meniscus extrusion at increasing varus forces was measured in both healthy knees and knees with a medial meniscus root-tear. We have also assessed the correlation between meniscal extrusion and functional outcome using VAS, WOMAC and SF-12 scores. Results: We analyzed nineteen patients (thirty-eight knees). There were seventeen knees with medial meniscus root-tear in the index group and twenty-one knees in the control group. Average extrusion distance for the index group was 5.3mm without varus force, 6.4mm with 100% varus force and 6.8mm with 150% varus force. Average extrusion distance for the control group without varus force, 100% and 150% applied varus force was 1.7mm, 1.7mm and 1.9mm, respectively. Extrusion increase with 100% varus force was significantly higher in the index group (p¼0.0002). The correlation between greater increase of meniscal extrusion with varus force and WOMAC pain, stiffness and function scores was r¼0.14, r¼0.26 and r¼0.37, respectively. Conclusion: Our study demonstrates there is an increase of meniscal extrusion during varus stress in patients with medial meniscus root-tear. Our results also suggests there is some correlation between meniscal extrusion and WOMAC scores, specifically with the WOMAC functional scale. Doctor: When Will I Feel Better After My Hip Arthroscopy? SS-30 April 27, 2018, 1:30 PM BENEDICT NWACHUKWU, MD, MBA, PRESENTING AUTHOR BRENDA CHANG, MS, MPH WILLIAM SCHAIRER, MD BRYAN T. KELLY, MD ANIL RANAWAT, MD Introduction: Minimal clinically important difference (MCID) defines outcome improvement that the patient perceives; little is known about when patients achieve MCID after femoroacetabular impingement (FAI) surgery. The purpose of this study was to investigate the time dependent nature of MCID after hip arthroscopy for FAI. Methods: A prospective institutional hip preservation registry was queried. The modified Harris Hip Score (mHHS), the Hip Outcome Score (HOS) and the international Hip Outcome Tool (iHOT-33) were administered to patients undergoing hip arthroscopy for FAI. Outcome measures were classified into three time periods e 5-11 months (“6 months postoperative”); 11-23 months (“1 year post-opera- tive”) and 23-35 months (“2 years post-operative”). A distribution-based method was used to define MCID. Cumulative probabilities were calculated using Kaplan-Meier survival curve analysis. A Weibull parametric regression analysis evaluated the odds of achieving earlier MCID. Results: 719 patients undergoing primary hip arthroscopy were included. The mean age was 32.5 years (+10.5) and the majority were female (N¼380, 52.9%). Across all four outcome instruments patients had the highest probability for achieving MCID by the 6 month post-operative period. On the HOS-Sport 57%, 65% and 71% achieved MCID by the 6-month, 1 year and 2 year time periods respectively. A similar trend was demonstrated across other outcome tools. Likelihood for achieving MCID did not vary greatly between the 6 month and 1 year periods however there were significant differences between the 6 month and 2 year periods. Male gender, age less than 40 years, Outer- bridge score of 0 and lower pre-operative score are predictive of achieving earlier MCID. Conclusion: MCID is most commonly achieved after hip arthroscopy during the 6 month post-operative period however MCID gains continue until the two year follow- up period. These findings have important implications for counseling patients, setting expectations and defining episodes of care in hip preservation surgery. Hip Arthroscopy Versus Physical Therapy for Acetabular Labrum Tears: Interim Anal- ysis of a Prospective Randomized Trial SS-31 April 27, 2018, 1:35 PM JOHN W. STELZER, MS, PRESENTING AUTHOR RAVI AGRAWAL, BA NOAH QUINLAN, MD SHIVAM UPADHYAYA, MD KYLE ALPAUGH, MD SCOTT MARTIN, MD Introduction: Hip arthroscopy is an effective surgical intervention for patients with symptomatic labral tears of the hip. Nonsurgical management may be a viable treat- ment modality for such patients. The purpose of this study is to compare the efficacy of physical therapy to the gold standard of hip arthroscopy for patients age 40 and older with a diagnosed symptomatic labral tear. Methods: Patients were prospectively identified and randomized into either arthroscopic surgical management (SPT) or comprehensive physical therapy (PTA). Inclusion criteria included patients over the age of 40 with a symp- tomatic acetabular labrum tear. Exclusion criteria included Tonnis 3 arthritis. Patients in PTA group were allowed arthroscopy after a minimum 8-week period of non- surgical management if desired improvement did not result (crossover). Arthroscopic treatment consisted of labral repair or labral debridement if repair was not possible. Demographic information, imaging studies, and baseline patient reported outcome measures (PROMs) were collected at enrollment and at 6, 12, and 24 months after initiation of treatment. Results: Of the 72 patients currently enrolled in the trial, we report 51eligible patients having completed at least 6-month follow-up. Average follow up was 15.2 months. Mean age and body mass index were 47.0Æ4.8 and 26.7Æ4.2, respectively. Subjects improved significantly from enrollment to follow-up in the SPT and PTA respectively. No significant differences in improvement were observed between the two groups. However, when comparing the 3 arms independently, the surgical groups (SPT and Crossover) outperformed physical therapy alone. 2018 AANA ABSTRACTS e13