Motion alterations six months and one year after partial medial meniscectomy

Introduction. Knee joint’s degenerative changes after meniscectomy are well known. Less evidence exists on underlying biomechanical alterations. Aim of this study is the investigation of lower limbs biomechanics before and after meniscectomy. The focus is on gait and squatting exercises. Gait is chosen because of its daily life role while squatting implies high stress of knee joint structure. Both the movements show high statistical repeatability intra and inter subjects. Materials and methods. Ten volunteers candidate to partial medial meniscectomy for meniscal tear underwent motion analysis just before surgery, six months and one year after. Ten healthy volunteers acted as a control group. All the subjects perform three gait trials and three squatting movements. Data were acquired by means of Vicon motion analyser and AMTI forces platform. Results. In gait patterns investigation, joint kinematics does not show significant modifications before and after surgery, while dynamic analysis stresses alterations in knee sagittal moment. Before surgery, healthy and affected limbs show significant differences, also referring to control group, at first impact and late stance. After surgery, asymmetries between limbs are no more significant at first impact, while the behaviour in late stance shows a reduced knee extension moment in the affected limb not present before surgery. In squatting investigation, main focus was on repeatability, being the mean behaviour consistent before and after surgery. Before surgery high inter subjects variability affects knee joint angle, stating pain response; while after surgery high variability affects also hip and ankle, suggesting a new approach to mechanical equilibriums. Conclusions. After meniscectomy, gait and squatting patterns are still altered. Before surgery, the joint mechanical structure is not highly altered and modifications are mainly due to pain avoidance schemas; after partial meniscectomy, pain disappears and the new joint behaviours are probably caused by the new mechanical asset and/or proprioceptive mechanisms.