Abstract
Objectives:
Residual impingement after hip arthroscopy for femoroacetabular impingement (FAI) is a common cause for re-operation; however, the relationship between preoperative and postoperative radiographic parameters and patient-reported outcomes has not been defined.
Methods:
749 consecutive patients were reviewed two years after primary hip arthroscopy. Patients undergoing revision surgery were excluded. Pre-operative and post-operative radiographs were analyzed to measure the alpha angle on standardized anteroposterior (AP) pelvis, Dunn-lateral, and false profile (FP) views and anterior and lateral center-edge angles (ACEA, LCEA). Univariate analysis evaluated the association between demographic variables, radiographic measures and hip outcome scores (Hip Outcome Score (HOS)-Activities of Daily Living (ADL), HOS-Sports Specific (SS), and Modified Harris Hip Score (mHHS)). Multivariate modeling was subsequently performed. Significance was defined as p<0.05.
Results:
706 patients with mean age of 33.2±12.3 years and mean BMI 25.1± 5kg/m2 were included for final analysis. The alpha angle on the AP, Dunn-lateral, and FP views and the ACEA and LCEA decreased after surgery (p<0.001 for all). Significant univariate correlations with the postoperative HOS-ADL included age, BMI, pre-operative AP, FP, and Dunn and postoperative FP alpha angles. Postoperative HOS-SS was correlated with age, BMI, medial post-operative joint space width (JSW), pre-operative AP, FP, and Dunn and postoperative FP alpha angles, and pre-operative and post-operative (ACEA). Postoperative mHHS correlated with age, BMI, post-operative lateral JSW, pre-operative AP, FP, and Dunn and postoperative FP and Dunn alpha angles, and post-operative ACEA. Multivariate modeling (Table 2) demonstrated that preoperative and postoperative FP alpha angles were independent predictors of postoperative outcomes.
Conclusion:
Pre-operative and post-operative alpha angles were negatively correlated with the HOS-ADL, HOS-SS, and mHHS at 2 years after arthroscopic surgery for FAI. Specifically, pre-operative and postoperative FP alpha angles were independent predictors of postoperative outcomes. These results highlight the importance of resecting anterior cam lesions to prevent residual impingement and inferior outcomes.
Table 2:
Multivariate Regression Results for Association Between Radiographic Measurements and Patient-Reported Outcome Scores
| Variable | Coefficient | P Value |
|---|---|---|
| HOS-ADL at 2 Years | ||
| Pre-op HOS-ADL score | 0.29 | <0.001 |
| Workmen's compensation | -8.51 | 0.045 |
| Pre-op AP alpha angle | -0.18 | 0.039 |
| Post-op false profile alpha angle | -0.42 | 0.030 |
| HOS-SS at 2 Years | ||
| Pre-op HOS-SS score | 0.33 | <0.001 |
| Workmen's compensation | -18.7 | 0.016 |
| Pre-op AP alpha angle | -0.43 | 0.005 |
| Pre-op false profile alpha angle | -0.30 | 0.039 |
| Modified Harris Hip Score at 2 Years | ||
| Pre-op MHHS | 0.32 | <0.001 |
| Age | -0.21 | 0.025 |
| Workmen's compensation | -11.3 | 0.044 |
| Pre-op false profile alpha angle | -0.17 | 0.046 |
| Post-op false profile alpha angle | -0.52 | 0.040 |