Postoperative alpha angle seems to be important for the achievement of clinical significance at a minimum 5-year follow-up after primary hip arthroscopy

Abstract

The purpose of the present study was to clarify whether there is an association of postoperative alpha value with functional scores or progression of osteoarthritis at X-rays at the midterm after arthroscopic treatment of femoroacetabular impingement (FAI) syndrome with femoral osteoplasty, labral repair or debridement and rim trimming. A retrospective review of prospectively gathered data from 2013 to 2017 was performed. All patients who underwent first-time unilateral hip arthroscopy for FAI resection with 5-year follow-up were included. Patient-reported outcomes included the modified Harris Hip Score (mHHS) and Visual Analog Scale for Pain (Pain VAS). The progression of osteoarthritis (Tonnis grade) and radiological parameters (alpha angle, lateral center-edge angle [LCEA] and head-neck offset) were evaluated. A receiver operating characteristic (ROC) analysis was used to evaluate the correlation between significant variables and achievement of patient-acceptable symptomatic state (PASS) and degree of osteoarthritis. We identified 52 patients with a minimum 5-year follow-up (average, 6.7 years). The average patient age was 33.9 +/- 11.5 years. There were 19 (36.5%) female patients. The mHHS improved from 60.1 +/- 13.4 before surgery to 86.8 +/- 14 after surgery (P < 0.001). The Pain VAS decreased from 6.21 before surgery to 2 after surgery (P < 0.001). Overall, 69% achieved the PASS for mHHS. The ROC curve for postoperative alpha angle demonstrated acceptable discrimination between patients achieving a fifth-year PASS value and those who did not have an area under the curve of 0.72. Patients having a postoperative alpha angle of <= 48.3 degrees achieved the fifth-year PASS value at a significantly higher rate than patients having a postoperative alpha angle of >48.3 degrees (P = 0.002). The postoperative alpha angle is a predictor of the achievement of the fifth-year PASS value for the mHHS. A threshold of <= 48.3 degrees had a sensitivity of 0.75 and a specificity of 0.69 to predict positivity. Level of evidence IV