Assessment of Association Between Spino-Pelvic Parameters and Outcomes Following Gluteus Medius Repair

Abstract

To evaluate postoperative coronal/sagittal spinal plane and spinopelvic parameters in patients undergoing gluteus medius repair and to identify associations between outcomes and the aforementioned spinopelvic variables. Patients who underwent gluteus medius/minimus repair by a single surgeon between January 20, 2012, and November 25, 2015, were retrospectively identified from a prospectively collected database. Radiographic measurements included Cobb angle, lumbar lordosis, sagittal vertical axis (SVA), pelvic tilt, sacral slope, and pelvic incidence. Patient-reported outcomes (PROs) were obtained at baseline and a minimum of 22months after surgery. Bivariate correlation determined effects of spinopelvic measurements on PROs. Scoliosis and nonscoliosis groups were compared using independent samples t-test, and multivariate analysis determined whether the preoperative variables affected outcomes. Thirty-eight (80.9%) of 47 consecutive patients were radiographically evaluated with a scoliosis series. All patients demonstrated significant improvements in all PROs and pain (P < .001 for all), as well as at an average 28.2 ± 7.8 (range, 22-51) months after surgery. There were significant negative relationships between SVA and Hip Outcome Score-Activities of Daily Living (r=-0.405, P= .026) and Hip Outcome Score-Sports Specific (r=-0.492, P= .011) scores. Patients with a positive SVA (>0cm) had significantly worse patient-reported outcomes than their counterparts with negative (≤0cm) SVA. Also, patients with positive sagittal plane deformity (SVA >5cm) had significantly worse HOS-SS than patients without positive sagittal plane deformity (SVA <5cm) (47.0 ± 35.3, 73.2 ± 24.0; P= .04). Independent sample t-testing for the patients with scoliosis (n= 18) versus no scoliosis (n= 20) demonstrates a significantly worse postoperative International Hip Outcome Tool (short version) score in the patients with scoliosis (77.4±15.1, 53.8 ± 37.1; P= .043). Patients with scoliosis presented with lower rates of symptom improvement and ability to return to an active lifestyle in patients with hip disorders. In addition, patients with positive sagittal plane deformity experienced lower hip-related sport-specific outcome scores. Although the direct relationship between the spine and the hip in patients after gluteus medius/minimus repair remains unclear, this study shows an association between these postoperative outcomes and spinopelvic parameters. Level IV, case series.