A prospective study for evaluation of knee effusion after hip surgery.

Knee effusion is a common occurrence in elderly patients following hip surgery. We prospectively studied 106 patients undergoing proximal femoral surgery. These patients were examined pre-operatively, on days 4 and 8, and six weeks post operatively for the presence of an ipsilateral knee effusion. 71 patients had undergone Total Hip Arthroplasty (THA), 26 Dynamic Hip Screw (DHS) insertion and 9 had hemiarthroplasty. The incidence of pre-operative ipsilateral knee effusion was 13% (14 patients). 42% (44 patients) had an effusion at one week post operatively and 12% (13 patients) at 6 weeks. 57% (60 patients) of the study group had radiological evidence of osteoarthritis in their knees. However, the incidence of effusion in patients with and without arthritis was the same. The majority of these effusions resolved after six weeks with no residual effects.