Gait analysis of pre- and post-meniscectomy knee: a prospective study.

Degenerative changes in the knee joint after meniscectomy are well known. Although likely to be due to changed biomechanics, there is no evidence in the literature to identify the underlying biomechanical alterations. The aim of this study was to analyse lower limb gait biomechanics before and after meniscectomy. Ten patients who required partial medial meniscectomy for irreparable meniscal tear took part in motion analysis before surgery, then at 6 and 12 months post-operatively. A control group was also set up consisting of 10 healthy volunteers. Joint kinematics did not show significant alterations between pre-operative and 6 month post-operative evaluations. However flexion increases at the hip, knee and ankle joint were observed in late swing and early stance phase 12 months after surgery. Hip and knee flexion-extension moments were affected with knee moment altered both before and after surgery. Before surgery and at 6 months after, the changes occurred mainly at the point of push off, while at 12 months they occurred during the swing phase. Hip flexion-extension moment had also changed 12 months after surgery. When examining symmetry of gait patterns prior to surgery, there were differences between the flexion-extension moments of the healthy and of the injured knee at first impact and during late stance. After surgery, asymmetries were not more apparent at first impact, but in late stance phase a reduced knee extension moment in the injured limb was still present. Before surgery, the joint kinematics were not greatly altered and changes were mainly due to pain. After partial meniscectomy, the pain disappeared and new joint responses were observed. These could be caused by the altered mechanics and/or through proprioceptive mechanisms.