Knee flexion contracture will lead to mechanical overload in both limbs: a simulation study using gait analysis.

The purpose of the current study was to investigate the effect of knee flexion contracture on the knee mechanics both in affected and contralateral limbs during gait. Ten healthy old women, with mean age of 62 years, participated. Unilateral knee flexion contractures of 0, 15, and 30 degrees were simulated with a knee brace. All subjects performed walking trials with or without the simulation. Net knee extension moments, net knee adduction moments (%BW Ht), external knee forces (%BW), and maximum axial loading rate (%BW/s) at the knee were calculated both in contracture side and non-contracture side under different contracture conditions. Bilateral net knee extension moment gradually increased as the angle of contracture increased. The net knee extension moments in non-contracture limb were significantly larger with 15 and 30 degrees contracture than those without the contracture. Net knee adduction moment in non-contracture limb significantly increased with 15 and 30 degrees contracture. The knee shearing forces in contracture side and the knee compressive force in non-contracture side also significantly increased with 15 and 30 degrees simulation. As the flexion contracture became greater than 15 degrees , maximum axial loading rate also significantly increased in non-contracture side. From our results, the knee flexion contracture greater than 15 degrees led to mechanical overloads in both limbs. Correction of the contracture is clinically important to avoid any adverse effect.