Lambers, Floor M.

Background: Recurrent anterior shoulder instability may lead to capsuloligamentous and bony lesions of the glenoid and humerus. To date, there is no clear consensus on how to best measure anterior glenoid bone loss (GBL) in the setting of recurrent instability. The objective of this study, therefore, was to evaluate the accuracy and reliability of 7 different methods of measuring anterior GBL on three-dimensional models based on computed tomography. Methods: Eight levels of GBL in the anterior and anteroinferior directions were virtually generated in 14 three-dimensional healthy glenoid models. GBL was measured with 7 different methods: based on a height/width ratio (M1), based on surface area within a circle (M2 and M3), based on linear distance within a circle, (M4, M5, and M6), and based on a volume ratio (M7). For each method, the measurement accuracy was assessed by comparing the calculated value with the true amount of generated GBL. The measurement reliability was assessed by computing the score variance and intraclass correlation coefficient. Results: The most accurate (average measurement error of <2% and largest proportion with error <5%) and reliable (ICC >0.96) measurement methods for GBL were M2 (based on surface area) and M5 (based on the linear distance). The average measurement error for the other methods ranged between 3% and 11% for anterior GBL and between 2% and 9% for anteroinferior GBL. For anterior GBL, the measurement increased by an average of 0.5% for each 1% increase in circle radius, leading to an overestimation of GBL with a larger circle diameter Conclusion: The methods for calculating glenoid bone loss performed better for the more common direct anterior bone loss rather than the less common anteroinferior-directed bone loss. Both an area-based method (M2) and linear distance–based method (M5) resulted in accurate and reliable measurements of glenoid bone loss; however, the linear distance–based methods may be easier to perform clinically. The height-width ratio and volume methods were less accurate and reliable. Level of Evidence: Level IV ; case series; diagnostic studies. See Instructions for Authors for a complete description of levels of evidence.

Background: Increased attention has been directed toward the acetabular morphology in the management of patients with femoroacetabular impingement syndrome (FAIS). Whether acetabular version influences patient-reported outcomes remains poorly understood. Purpose: To use computed tomography (CT)–based 3-dimensional (3D) bone models to (1) quantify acetabular version in patients with FAIS, (2) compare acetabular version on 3D bone models with current plain radiographic parameters, and (3) explore the relationship between the magnitude of acetabular version and minimum 2-year clinical outcomes after hip arthroscopy. Study Design: Cohort study; Level of evidence, 3. Methods: Three-dimensional models of the pelvis and femur were generated by semiautomated segmentation and aligned to a standard coordinate system. Acetabular version was quantified at the 3-o’clock position, and 3 groups were identified: acetabular retroversion (AR; <15°), normal acetabular version (NV; 15°-25°), and acetabular anteversion (AA; >25°). Patient demographic characteristics, plain radiographic parameters, and clinical outcomes were analyzed, including the Hip Outcome Score–Activities of Daily Living, Hip Outcome Score–Sports Subscale, modified Harris Hip Score (mHHS), International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction. Results: Preoperative CT scans were acquired in 105 consecutive patients before hip arthroscopy for FAIS, of which 84 (80.0%) completed minimum 2-year patient-reported outcomes. The mean ± SD age and body mass index of patients were 33.9 ± 12.6 years and 26.0 ± 5.4, respectively; 70.2% were female. The number of patients and the mean central acetabular version within each group were as follows: AR (n = 12; 11.3°± 2.7°), NV (n = 56; 20.7°± 2.9°), and AA (n = 16; 28.5°± 2.7°). Posterior wall sign was the only plain radiographic parameter that was significantly more observed in the AR group than in the other 2 groups. At minimum 2-year follow-up, significant between-group differences in the mHHS, iHOT-12, and VAS for pain and satisfaction ( P < .05) were appreciated, while post hoc analysis with Bonferroni correction ( P < .0167) found lower scores on the mHHS, iHOT-12, and VAS for pain and satisfaction in patients with AR as compared with NV. Lower scores on the VAS for satisfaction were reported in patients with AR when compared with AA ( P = .006) but not on the mHHS ( P = .023), iHOT-12 ( P = .032), or VAS for pain ( P = .072). Conclusion: Traditional plain radiographic indices to describe AR, including crossover sign and ischial spine sign, were not reliable in defining AR according to 3D models derived from CT scans. Only the posterior wall sign was observed in a higher proportion in the AR group. Patients with AR demonstrated inferior outcomes when compared with patients with NV and AA after hip arthroscopy for FAIS.