Reconstruction of the hip abductor function with a deep muscle-sparing vastus lateralis to gluteus medius translational transfer/transposition

Aims: The aim of this study is to describe a deep muscle-sparing vastus lateralis (VL) flap to gluteus medius (Gmed) transfer to address severe hip abductor function deficiency, and present the early results achieved through a multidisciplinary team (MDT) approach. Methods: Seven patients, with and without previous total hip arthroplasty, with severe abductor deficiency of the hip (Medical Research Council ≤ 2/5), and requiring walking aids, underwent a deep muscle-sparing VL translation flap to Gmed as part of a new orthopaedic and plastic MDT approach, and had more than 12 months' follow-up. The fatty infiltration of the glutei had a median Goutallier scale of 4 (IQR 1 to 4). Five patients had prior revision surgery, two involving a proximal femoral arthroplasty. Patients underwent pre- and postoperative evaluations with clinical examination, instrumented gait analysis, surface electromyography (EMG), and MRI. Results: All patients were satisfied with the result and could walk without support by six months after surgery. The abductor power improved to 3 to 5 out of 5 and continued to improve beyond one year after surgery. Knee extension power was not affected. EMG demonstrated that the transferred VL activated synchronously with Gmed three months postoperatively, suggesting adaptation to its new function. MRI demonstrated no fatty infiltration of the flap or the residual VL. Conclusion: The MDT approach to hip abductor function reconstruction with VL to Gmed transfer has demonstrated potential for success, with good functional outcomes and no functional donor-site morbidity recorded to date.