System and Function Study of Limb Compression after Total Knee Replacement / 医用生物力学

ABSTRACT

Objective A three-dimensional （3D） printing precise pressure device was designed specifically targeted at cambered limbs according to the requirement of postoperative rehabilitation of total knee replacement(TKR), and its effectiveness and safety was verified by finite element analysis. Methods Based on gastrocnemius muscle of lower limbs as the pressurized objects, the precise pressure device was designed, which contained an air pressure generating module, an inflatable airbag and a 3D printing brace. Through the closed loop control algorithm, the device stably supplied different pressures in the airbag. Distributed pressure data of the airbag-skin within contact surface were collected under different experimental conditions and imported into biomechanical simulation software which combined CT images to reconstruct 3D model of the lower limb mechanics. Finally, the effective compression area fraction and the joint micro-motion angle under each condition were obtained, to verify the effectiveness and safety of the system. Results Using generally preferred 4 cm-size offset and 4-barrel airbag configurations, under different intracapsular pressure of 5.32，6.65，7.98，9.31，10.64 kPa, the simulated knee joint micro-motion angles were 5.3°, 6.1°, 7.2°, 9.5°, 10.6°， respectively, and the effective compression area fraction could be up to 90-8%-95-2%. Conclusions For the optimized scheme, the dynamic range of joint micro-motion angle and the effective compression area fraction caused by different airbag pressure values were the best and met the design requirements of effectiveness and safety. The research findings can contribute to analyzing the influence of compression system on limb biomechanics, which are of great significance for effective and safe rehabilitation training after TKR.