Hip Gluteus Medius Tears Are Associated With Lower Femoral Neck-Shaft Angles and Higher Acetabular Center-Edge Angles.

PURPOSE: 1) To assess the possible relationship between the morphology of femur or acetabulum and the gluteus medius pathology. 2) To analyze the outcome of isolated arthroscopic treatment of femoroacetabular impingement (FAI) for patients with radiographic gluteus medius tear. METHODS: We performed a retrospective study of FAI patients who underwent arthroscopy between January 2016 to December 2019. Demographic data, such as sex, age, body mass index (BMI), symptom duration, were collected. Radiographic parameters, including alpha angle, lateral center-edge angle (LCEa), femur neck-shaft angle (NSa), gluteus medius pathology, were also collected. Exclusion criteria were previous hip conditions, such as osteoarthritis (Tönnis grade > 1), rheumatoid arthritis, ankylosing spondylitis, snapping hip, previous surgery on the ipsilateral hip, or incomplete data. We followed up these patients with radiographic gluteus medius tear. No surgical procedure for gluteus medius was performed. The minimum follow-up period was 13 months. Patient-reported outcomes, such as modified Harris Hip score (mHHS), visual analog scale (VAS), and patient acceptable symptom state (PASS), as well as physical examination data, including tenderness at the greater trochanter, abductor weakness, limping gait, and positive Trendelenburg sign or test, were gathered preoperatively and postoperatively. RESULTS: A total of 569 hips (314, 55.2% male) were collected eventually, with a mean age of 36.5 ± 10.4 years (range: 13.0 to ∼65.0). Gluteus medius pathology was found in 209 (36.7%) hips, including 41 (7.2%) partial-thickness tears and 10 (1.8%) complete tears. The NSa of the normal, tendinosis, partial tear, and complete tear groups was 133.8 ± 4.7°, 130.6 ± 3.8°, 129.4 ± 3.9°, and 129.6 ± 3.4°, respectively (P < .001). The LCEa of each group was 31.7 ± 35.7°, 33.3 ± 6.5°, 34.9 ± 6.8°, and 33.7 ± 8.1°, respectively (P = .004). On multivariable logistic regression analysis, lower NSa and higher LCEa were identified as risk factors for developing gluteus medius pathology (P < .001). For patients with gluteus medius tear, two cases were lost to follow-up and two cases had incomplete data. The mean follow-up period of the remaining 47 hips was 29.5 ± 12.9 (range: 13 to 59) months. The mHHS improved from 54.8 ± 19.1 to 90.1 ± 6.7 points (P < .001), and VAS decreased from 6.8 ± 1.6 to 3.0 ± 1.6 points (P < .001). Forty-two cases met the threshold of PASS, with a rate of 89%. The abductor strength increased from 4.1 ± 1.00 to 4.6 ± .7 grades (P = .002). However, for patients with a completely torn gluteus medius, improvement of abductor strength was not significant statistically (3.4 ± .9 to 3.9 ± .9, P = .234). CONCLUSION: There was a correlation between lower NSa/higher LCEa and gluteus medius pathology. Isolated arthroscopic treatment of FAI for patients with radiographic gluteus medius tear can gain satisfactory patient-reported outcomes. LEVEL OF EVIDENCE: Therapeutic case series, IV.

Volume of Gluteus Maximus and Minimus Increases After Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

PURPOSE: To investigate the change in muscle volume around the hip in patients with femoroacetabular impingement (FAI) after arthroscopy and evaluate other factors related to muscle change. METHODS: We performed a retrospective review of magnetic resonance imaging data of patients with FAI who underwent hip arthroscopy. Magnetic resonance imaging was obtained pre- and postoperatively. The cross-sectional area (CSA) of muscles were determined on axial images. The Wilcoxon signed-rank test was used to determine the differences between pre- and postoperative hip muscle CSA. The correlations of change in muscle CSA with age, sex, body mass index, pain level, preoperative symptom duration, follow-up time, and multiple validated patient-reported outcomes were also analyzed with a Spearman rank correlation test. RESULTS: Fifty-one patients with a mean age of 36.5 ± 5.6 years were included and analyzed. The follow-up was 26.6 ± 0.5 months (range, 24-40 months), and 27 (52.9%) were women. Patients with FAI showed increased hip muscle CSA of gluteus maximus (P = .002) and gluteus minimus (P = .001). Post- compared with preoperative, the value for the change in medius CSA was underpowered, and no differences in other hip muscle CSAs were observed. The increased muscle CSA of the gluteus maximus was significantly correlated with the improvement of modified Harris Hip Score (ρ = 0.404; P = .003). The increased muscle CSA of the gluteus minimus was significantly correlated with the improvement of pain Visual Analog Scale (ρ = 0.452; P = .001). Age, body mass index, sex, symptom duration, and follow-up time were not significantly correlated with change in muscle CSA. CONCLUSIONS: Patients with FAI have a significantly increased postoperative muscle CSA of the gluteus maximus (7.8%) and the gluteus minimus (11.6%) compared with preoperative values. The increased muscle CSA of the gluteus maximus and gluteus minimus was significantly correlated with improvement in modified Harris Hip Score and pain Visual Analog Scale, respectively. The increase of muscle volume may be associated with the improvement of subjective function and pain relief. LEVELS OF EVIDENCE: Level IV, therapeutic case series.