Do Femoral Head Osteochondral Lesions Predict a Poor Outcome in Hip Arthroscopy Patients? A Matched Control Study with Minimum 5 Year Follow-Up
Objectives: Cartilage lesions of the femoral head identified at arthroscopy are less common than those involving the acetabulum and potentially portend a worse outcome. We sought to determine whether the finding of a femoral head lesion at hip arthroscopy, in and of itself, affected the outcomes of patients undergoing hip arthroscopy.
Methods: Between April 2008 and March 2011, data were prospectively collected for all patients who underwent hip arthroscopy at our institution. Inclusion criteria were femoral head osteochondral lesions, labral tear, and preoperative patient-reported outcome scores (PROs). Exclusion criteria were previous ipsilateral hip surgery, prior hip conditions, inflammatory conditions, workman’s compensation claims, and preoperative Tönnis grade ≥ 1. Patients with femoral head lesions (FH) were then matched to patients without femoral head lesions (control) for age, BMI, gender and lateral center edge angle (LCEA). Patient reported outcome scores (PROs), including modified Harris hip score (mHHS), non-arthritic hip score (NAHS) and hip outcome score-sport specific subscale (HOS-SSS) were collected preoperatively and postoperatively at 3 months and annually thereafter. In addition, visual analogue scores (VAS) for pain and patient satisfaction were noted. Lastly, revision surgery, conversion to total hip arthroplasty (THA) and any complications were collected and compared.
Results: During the study period, 687 hip arthroscopies were performed at our institution. After applying inclusion and exclusion criteria, 96 patients in the FH group were matched to 96 in the control group. There were more females than males (62.5% vs 37.5%, respectively). Average age at the time of surgery was 44 years and average BMI was 26 in each group. Average follow up was longer for the FH group versus control (71 vs 67 months respectively, p=0.0035). All PROS, VAS, and patient satisfaction were significantly improved at latest follow up in both groups. There was no difference in the degree of improvement (Δ PROs and ΔVAS) between the FH and controls. However, patients with FH lesions had a higher rate of conversion to arthroplasty (32 % vs15%, p=0.0027 at an average of 39 and 30 months, respectively). Patients in the control group underwent more revision arthroscopies (24% vs 5%, p=0.05). A higher percentage of patients who later converted to THA were older at the time of surgery, had higher BMI, and Tönnis grade of 1. Additionally, more patients with worse outcomes had lower preoperative NAHS and alpha angles over 60 degrees.
Conclusion: The finding of a femoral head lesions at arthroscopy does not, in and of itself, portend a worse outcome. Acetabular Outerbridge grade 4 portended a worsened outcome, while 0 portended a better one. When combined with other factors such as older age at surgery, higher BMI, Tonnis grade 1, lower preoperative NAHS and alpha angle greater than 60°, lower outcome scores and higher rates of conversion to arthroplasty can be expected.