Summary

Outcomes at 5-year follow up did not show a significant difference between patients with anterior/anterolateral and lateral cam lesions based on mHHS, NAHS, MCID, SCB and pass PASS scores.

Abstract

Objective

The purpose of this study was to compare symptoms, operative findings and 5-year outcomes of patients who underwent hip arthroscopy for cam lesions associated with femoroacetabular impingement (FAI).

Methods

We conducted a retrospective review of prospectively collected data of patients with cam lesions who underwent hip arthroscopy for FAI between September 2011- March 2014 with a minimum 5-year follow up. Preoperative data included age, BMI, sex, and pre-operative symptom duration (<1 year versus =1 year). Cam lesion locations were grouped based on which radiographic view displayed the largest alpha angle. Alpha angles largest on anterior-posterior (AP) views were defined as superolateral, those largest on 45° Dunn as anterolateral and those largest on 90° Dunn as anterior. Patient reported outcomes (PROs) including the modified Harris Hip Score (mHHS) and Nonarthritic Hip Score (NAHS) were completed preoperatively and at 5 years. Achievement of the minimal clinically important differences (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state PASS) were determined using established cutoff values for the mHHs. Operative findings recorded included the Outerbridge grade for acetabular chondromalacia, the presence of labral tears, chondral delamination, subspine impingement, and pincer lesions. In addition, the Tönnis grade and presence of crossover sign were measured on the AP view.

Results

Data was collected on one hundred fifty-six patients from our single-surgeon database who underwent primary hip arthroscopy for FAIS and had minimum five-year follow-up. Of those, 31 were excluded due to absence of cam lesions, missing hip radiographic views or missing PROs at baseline and/or at 5-year follow-up. The final cohort consisted of 125 patients, 71 (56.8%) with superolateral lesions, 41 (32.8%) with anterolateral and 13 (10.4%) with anterior. Sex, BMI, Tönnis grade, and acetabular Outerbridge grade were not significantly different between groups (p > 0.05). The anterior and anterolateral cam groups were significantly older than the superolateral cam group (ANT 46.6y vs. AL44.7y vs. LAT 38.1y, p = 0.006). At baseline the anterior cam lesions had the lowest baseline mHHS (mean 46.9) followed by the anterolateral cam group (mean 48.8) and superolateral cam group (mean 52.8) though these inter-group differences were not statistically significant (p = 0.19). Baseline NAHS scores were comparable between the groups (ANT 48.5 vs. AL 47.9 vs. LAT 50.7, p = 0.65). Multivariable analysis revealed that anterolateral lesions were found to be significantly predictive of lower odds of undergoing THA compared to lateral lesions (OR 0.01, 95% CI [<0.01, 0.72], p = 0.03). There were no significant inter-group differences in the five-year improvement in mHHS (p = 0.29) or NAHS (p = 0.65). The anterior cam group experienced the lowest achievement rates for the MCID (81.8%) and the SCB (81.8%) while the anterolateral cam group experienced the lowest achievement rate for the PASS (81.3%). None of the inter-group differences in MCID, SCB, and PASS achievement rates reached statistical significance (p > 0.05).

Conclusion

Pre-surgical, operative and 5-year follow up findings were not significantly different between patients with cam lesions of different locations. Overall, 5-year outcomes following correction of cam lesions in patients with FAIS are favorable, yet those with superolateral lesions who undergo hip arthroscopy more often require THA.