The Gluteus-Score-7 Predicts the Likelihood of Both Clinical Success and Failure following Surgical Repair of the Gluteus Medius and/or Minimus.

PURPOSE: Identify patient preoperative history, exam, and imaging characteristics that increase risk of postoperative failure of gluteus medius/minimus repair, and to develop a decision-making aid predictive of clinical outcomes for patients undergoing gluteus medius/minimus repair.

METHODS: Patients from 2012-2020 at a single institution undergoing gluteus medius/minimus repair with minimum two-year follow-up were identified. MRIs were graded according to the "Three-Grade" classification system: grade 1: partial thickness tear, grade 2: full thickness tears with <2cm of retraction, grade 3: full thickness tears with ≥2cm retraction. Failure was defined as undergoing revision within two years postoperatively or not achieving both a cohort-calculated minimal clinically important difference (MCID) and responding 'NO' to patient acceptable symptom state (PASS). Inversely, success was defined as reaching both an MCID and responding 'YES' to PASS. Predictors of failure were verified on logistic regression and a predictive scoring model, the Gluteus-Score-7, was generated to guide treatment-decision making.

RESULTS: 30/142 patients (21.1%) were clinical failures at mean±SD follow-up of 27.0±5.2 months. Preoperative smoking (OR, 3.0; 95% CI, 1.0-8.4; p=0.041), lower back pain (OR, 2.8; 95% CI, 1.1-7.3; p=0.038), presence of a limp or Trendelenburg gait (OR, 3.8; 95% CI, 1.5-10.2; p=0.006), history of psychiatric diagnosis (OR, 3.7; 95% CI, 1.3-10.8; p=0.014), and increased MRI classification grades (p<0.042) were independent predictors of failure. The Gluteus-Score-7 was generated with each history/exam predictor assigned 1 point and MRI classes assigned corresponding 1-3 points (min 1, max 7 score). A score of ≥4/7 points was associated with risk of failure and a score <2/7 points was associated with clinical success.

CONCLUSION: Independent risk factors for revision or not achieving either MCID or PASS after gluteus medius and/or minimus tendon repair include smoking, preoperative lower back pain, psychiatric history, Trendelenburg gait, and full-thickness tears, especially tears with ≥2cm retraction. The Gluteus-Score-7 tool incorporating these factors can identify patients at risk of both surgical treatment failure and success, which may be useful for clinical decision-making.

LEVEL OF EVIDENCE: Prognostic: Level IV (case series).