The Importance of Comprehensive Cam Correction: Radiographic Parameters Are Predictive of Patient-Reported Outcome Measures at 2 Years After Hip Arthroscopy
Authors: Lansdown Drew A. , Kunze Kyle , Ukwuani Gift , Waterman Brian R. , Nho Shane J. 
Published: June 2018

Background:

The specific influence of preoperative and postoperative radiographic measurements on patient-reported outcome measures after hip arthroscopy for femoroacetabular impingement (FAI) remains unclear.

Purpose:

To investigate the relationship between radiographic measurements and 2-year outcomes after hip arthroscopy for the treatment of FAI.

Study Design:

Case series; Level of evidence, 4.

Methods:

A clinical registry of patients undergoing primary hip arthroscopy for FAI between January 1, 2012, and December 31, 2014, was queried. Outcome measures included the Hip Outcome Score (HOS) Activities of Daily Living (ADL), HOS Sport-Specific Subscale (SSS), modified Harris Hip Score (mHHS), and visual analog scale (VAS) for pain and satisfaction. Preoperative and postoperative radiographic measurements were recorded. Univariate analysis was conducted to identify relationships between all radiographic and demographic variables and outcome scores. A multivariate regression analysis, controlling for demographic factors, was used to identify independent associations between radiographic measurements on plain radiographs and patient-reported outcomes.

Results:

The authors identified 707 patients who underwent primary hip arthroscopic management for FAI who were included for analysis. Two-year outcome surveys were completed for 78% to 84% of patients. The mean age of the patients was 33.2 ± 12.3 years, and 64.4% of the patients (n = 456) were female. The mean anteroposterior (AP) alpha angle decreased by 34.3° ( P < .0001), false profile alpha angle by 25.2° ( P < .0001), Dunn lateral alpha angle by 28.9° ( P < .0001), lateral center edge angle by 2.6° ( P < .0001), and anterior center edge angle by 3.4° ( P < .0001). The HOS-ADL score increased from 65.7 ± 18.7 preoperatively to 85.9 ± 16.7 postoperatively ( P < .0001), HOS-SSS increased from 43.4 ± 23.1 to 72.6 ± 27.2 ( P < .0001), and mHHS increased from 57.7 ± 14.0 to 79.1 ± 17.2 ( P < .0001). With multivariate analysis, independent predictors of the postoperative HOS-ADL score included the preoperative false profile alpha angle (beta = −0.16, P = .028). Independent predictors of HOS-SSS score were preoperative AP alpha angle (beta = −0.33, P = .032) and preoperative false profile alpha angle (beta = –0.28, P = .041). For the postoperative mHHS score, independent predictors included preoperative AP alpha angle (beta = −0.18, P = .046), preoperative false profile alpha angle (beta = −0.20, P = .014), and postoperative false profile alpha angle (beta = –0.48, P = .035). The preoperative AP alpha angle (beta = 0.28, P = .024) was a significant predictor for the postoperative VAS pain score. The preoperative false profile alpha angle (beta = −0.34, P = .040) was a significant predictor for the postoperative VAS satisfaction score.

Conclusion:

The authors observed that radiographic measurements, specifically the preoperative false profile alpha angle, AP alpha angle, and postoperative false profile alpha angle, are independent predictors of 2-year clinical outcomes. The femoral-side measurements were the strongest independent predictors of outcomes, especially measurements of the anterior and lateral-based CAM lesion.