Hip isometric strength following knee surgery.

Hip exercises are frequently prescribed following knee injury and subsequent surgery based on the assumption that hip weakness exists. No data, however, are available that support hip weakness following knee trauma or surgery. Therefore, the purpose of this study was to compare hip strength in patients after knee surgery. Twenty-seven patients who had undergone unilateral knee surgery were tested for hip flexor, extensor, abductor, and adductor isometric strength prior to initiation of rehabilitation. Multivariate analysis of variance revealed significant hip weakness in all four hip muscle groups of the surgical extremities (11.9-25.3%, p < or = 0.05) when compared with nonsurgical extremities. Both peak and endurance force were affected. The greatest percent difference between the surgical and nonsurgical extremity occurred for hip extension peak (25.3%) and endurance (22.6%) force development. We recommend assessment of hip strength following knee surgery and appropriate resistive exercises if weakness exists.