ePoster #747 - ISHA Annual Scientific Meeting 2016

Early Effects of Arthroscopic Treatment for Cam-type FAI on Patient Outcomes and Articular Cartilage Health

Alan L. Zhang, MD, San Francisco, CA UNITED STATES
Matthew C. Gallo, BA, San Francisco, CA UNITED STATES
Michael A. Samaan, PhD, San Francisco, CA UNITED STATES
Benedikt J. Schwaiger, MD, San Francisco, CA UNITED STATES
Thomas M. Link, MD, PhD, San Francisco, CA UNITED STATES
Sharmila L. Majumdar, PhD, San Francisco, CA UNITED STATES
Richard B. Souza, PT, PhD, San Francisco, CA UNITED STATES

University of California, San Francisco Medical Center, San Francisco, California, UNITED STATES

FDA Status Not Applicable

Summary: Quantitative cartilage imaging may indicate an acute increase in stress to articular cartilage at the anterosuperior aspect of the femoral head within 6 months of arthroscopic femoroplasty for treatment of cam-type FAI. Despite these findings, patient reported outcomes including pain and activity level improved significantly after surgery.

Background: Femoroacetabular impingement (FAI) has been identified as a significant cause of hip pain and early osteoarthritis (OA) in young and middle-aged patients. Increased awareness for FAI has led to a rapid rise in arthroscopic treatments including osteochondroplasty and labral repair. However, the effects of these procedures on articular cartilage health are unknown. Recent studies have demonstrated the ability of quantitative magnetic resonance imaging (QMRI) sequences including T1rho and T2 mapping to assess early cartilage degeneration in the hip. Elevated T1rho and T2 relaxation times have been associated with changes in cartilage composition that signal early injury. The purpose of this study is to evaluate acute changes in articular cartilage biochemical composition after arthroscopic treatment for FAI using QMRI and to correlate results with patient reported outcomes (PRO). Methods: Patients undergoing arthroscopic surgery for cam-type FAI without cartilage degeneration findings (joint space narrowing, osteophytes, full-thickness cartilage lesions, subchondral edema) were recruited for this study. All patients were treated with femoroplasty and labral repair (patients requiring microfracture were excluded) by a sports medicine fellowship-trained hip arthroscopist. Patients obtained unilateral 3T MRI studies of the hip prior to surgery (baseline) and 6 months after treatment. Acetabular and femoral cartilage compositions were assessed using a 3D combined T1rho and T2 mapping sequence to quantify relaxation times. The Hip disability and Osteoarthritis Outcome Score (HOOS) was surveyed at baseline and 6-month follow-up. Paired t-tests were used to evaluate longitudinal changes in T1rho and T2 relaxation times and HOOS subscales while Pearson correlations were used to evaluate the association between T1rho or T2 values and HOOS subscales at both time points. Results: Twelve patients (10 male, 2 female, mean age=40, BMI=24.2) with cam-type FAI were treated with arthroscopic femoroplasty and labral repair. Baseline QMRI findings demonstrated increased T1rho and T2 relaxation times to be correlated with lower HOOS subscores. At 6-month follow-up after surgery, all patients showed significant improvements in HOOS pain (mean change 22.7 ± 17.3, p=0.001), symptoms (14.2 ± 18.2, p=0.021), activities of daily living (25.6 ± 21.0, p=0.001), sports (38.0 ± 23.0, p<0.001), and quality of life subscores (39.6 ± 16.5, p<0.001). Acetabular articular cartilage demonstrated no significant changes in biochemical composition between pre-op and 6 month post-op scans. Articular cartilage at the anterosuperior aspect of the femoral head (zone 2) demonstrated increased T1rho (mean change 2.4 ± 3.0 ms, p=0.02) and T2 relaxation times (2.3 ± 2.2 ms, p=0.003) 6 months after arthroscopy. There were no significant correlations between changes in cartilage relaxation times and changes in HOOS subscores after surgery. Discussion/Conclusion: Although patient reported outcomes improved significantly 6 months after arthroscopic treatment for cam-type FAI, quantitative cartilage imaging may indicate an acute increase in stress to articular cartilage at the anterosuperior aspect of the femoral head. This may be a result of increased loading to this region after femoroplasty of the head-neck junction. Further analysis is needed to evaluate changes in articular cartilage health after FAI surgery and effects on patient outcomes with prolonged follow-up.