Rehabilitation outcomes following a periacetabular osteotomy (PAO): a case study

Abstract

Hip dysplasia is a joint deformity creating instability at the hip due to decreased acetabular coverage of the femoral head and often leads to osteoarthritis. A periacetabular osteotomy is a procedure designed to preserve the bony anatomy and delay the development of osteoarthritis. There is little known about the resulting biomechanical outcomes following periacetabular osteotomy. Two studies on a single subject having undergone periacetabular osteotomy are addressed here: 1) how does lower extremity function during a sit-to-walk change throughout recovery compared to preoperative values following a unilateral periacetabular osteotomy and 2) does gait retraining using real-time biofeedback of ground reaction forces improve return of gait function, with regard to internal hip joint moments, hip and pelvis kinematics, whole body center of mass velocity, and step length following bilateral periacetabular osteotomy in a single patient. In study one, patient reported outcomes, hip strength, and lower extremity joint moments and contributions to peak support moment during the sit-to-stand were assessed pre-operatively and at 6 weeks, 12 weeks, 6 months, and 13 months following periacetabular osteotomy. Patient reported outcome scores returned to normative ranges, however overall quality of life scores remained low. By 13 months muscle strength recovered to baseline values. Following surgery, peak support and hip extensor moments were higher on the non-surgical limb, but the contributions of hip, knee, and ankle to peak support moment did not change. On the surgical limb, while peak support moments were lower, the hip contributed less, and the knee contributed more. These asymmetric loading patterns gradually normalized over one year. In study two, hip joint kinematics, moments, vertical ground reaction forces, and symmetry between limbs during gait were assessed at 6 and 12 weeks following bilateral periacetabular osteotomy - one with gait intervention, and one without. Limb symmetry across dependent variables was not improved in the gait retraining intervention compared to the control. Future research examining biomechanical outcomes in the immediate window following periacetabular osteotomy are needed in addition to evaluation of similar interventions to better inform the rehabilitation protocols currently in place and improve patient return to baseline activity.