Aims. Rotational acetabular osteotomy (RAO) is an effective joint-preserving surgical treatment for acetabular dysplasia. The purpose of this study was to investigate changes in muscle strength, gait speed, and clinical outcome in the operated hip after RAO over a one-year period using a standard protocol for rehabilitation. Patients and Methods. A total of 57 patients underwent RAO for acetabular dysplasia. Changes in muscle strength of the operated hip, 10 m gait speed, Japanese Orthopaedic Association (JOA) hip score, and factors correlated with hip muscle strength after RAO were retrospectively analyzed. Results. Three months postoperatively, the strength of the operated hip in flexion and abduction and gait speed had decreased from their preoperative levels. After six months, the strength of flexion and abduction had recovered to their preoperative level, as had gait speed. At one-year follow-up, significant improvements were seen in the strength of hip abduction and gait speed, but muscle strength in hip flexion remained at the preoperative level. The mean JOA score for hip function was 91.4 (51 to 100)) at one-year follow-up. Body mass index (BMI) showed a negative correlation with both strength of hip flexion (r = -0.4203) and abduction (r = -0.4589) one year after RAO. Although weak negative correlations were detected between strength of hip flexion one year after surgery and age (r = -0.2755) and centre-edge (CE) angle (r = -0.2989), no correlation was found between the strength of abduction and age and radiological evaluations of CE angle and acetabular roof obliquity (ARO). Conclusion. Hip muscle strength and gait speed had recovered to their preoperative levels six months after RAO. The clinical outcome at one year was excellent, although the strength of hip flexion did not improve to the same degree as that of hip abduction and gait speed. A higher BMI may result in poorer recovery of hip muscle strength after RAO. Radiologically, acetabular coverage did not affect the recovery of hip muscle strength at one year’s follow-up. A more intensive rehabilitation programme may improve this. Cite this article: Bone Joint J 2019;101-B:1459–1463

Introduction. Femoroacetabular impingement (FAI) is a morphological hip joint deformity associated with pain and early degenerative changes. Cam-type FAI is prevalent in young male athletes. While biomechanical deficiencies (decreased hip muscle strength and range of motion (ROM)) have been associated with symptomatic cam-type FAI (sFAI), results have been conflicting and little is known about biomechanical characteristics during dynamic tasks. Objectives. (1) Compare coronal-plane hip muscle strength, activation and joint rotation during movement tasks in sFAI hips against healthy controls. (2) Investigate the effect of hip internal rotation ROM (IR-ROM) on these outcomes. Methods. 11 sFAI and 24 well-matched healthy control hips from 18 young adult male athletes were recruited (Table.1). Passive hip IR-ROM was measured with goniometry. Weight-normalised hip abductor and adductor isometric maximal voluntary contraction torques were quantified with handheld dynamometry. Gluteus medius and adductor longus activation and hip coronal-plane kinematics were collected with surface electromyography (EMG) and motion-capture during time-defined phases of sit-to-stand (Fig.1) and single-leg-squat (Fig.2) tasks. Effect of sFAI with hip IR-ROM as a separate independent variable was calculated with 1-way MANCOVA. Results. sFAI had significantly less IR-ROM (19.25°±5.94) than controls (28.83°±7.24) (p<0.001). During the sit-to-stand ascent phase, significantly more hip abduction (F=4.93, p=0.03) was observed in sFAI (13.06°±3.16) compared to controls (10.16°±3.72). With IR-ROM differences controlled for, significantly higher gluteus medius:adductor longus EMG activation ratio (F=4.32, p=0.046) was observed in the same phase in sFAI (0.16±0.34) compared to controls (−0.11±0.31). No other significant results were found. Conclusion. sFAI hips demonstrate altered muscle activation and movement patterns when ascending from seated positions compared to controls, with reduced hip IR-ROM in sFAI hips influencing findings. Abductor and adductor function imbalance may explain why sFAI increases risk of early degenerative changes. Despite study limitations (no imaging for sFAI diagnosis), these findings should be considered when optimising rehabilitation in this population. For any figures and tables, please contact the authors directly

Aims

Complex total hip arthroplasty (THA) with subtrochanteric shortening osteotomy is necessary in conditions other than developmental dysplasia of the hip (DDH) and septic arthritis sequelae with significant proximal femur migration. Our aim was to evaluate the hip centre restoration with THAs in these hips.