Objective: to analyze the shape and function of the regenerated hamstring tendon within 2 years after the removal of the hamstring tendon in ACL reconstruction, reveal the change rule of the characteristics of hamstring tendon regeneration and its biomechanical changes, and guide the selection of operation and postoperative rehabilitation.~Methods: 55 healthy people and 55 male patients with ACL reconstruction were recruited. All completed the basic rehabilitation training under the guidance of the postoperative rehabilitation program. Using infrared motion capture system, three-dimensional force measuring platform, isokinetic muscle force testing system and ultrasound, the anterior cruciate ligament reconstruction patients were tested before operation, 2 weeks, 3 months, 6 months, 12 months after operation and 24 months after operation.~Outcome evaluation indicators and statistical methods: evaluation indicators: (1) three dimensional motion capture and analysis results: 1) peak ground reaction force; 2) three-dimensional angle and torque of hip, knee and ankle joints in different stages; (2) isokinetic muscle strength results: bilateral knee extension torque and knee flexion torque at different angles and angular velocities. (3)Ultrasound evaluation: the thickness, cross-sectional area and shear wave velocity of the semitendinosus were measured.~Statistical methods: ① repeated measurement analysis of variance (ANOVA) was used to test the effects of different time after operation on the three-dimensional gait characteristics, muscle strength and tendon regeneration characteristics. ② Independent sample t-test was used to test the three-dimensional characteristics, muscle strength and tendon condition of patients at different time points after operation. ③ The difference of three-dimensional gait characteristics, muscle strength and tendon between the healthy side and the affected side at different time points after operation were examined by paired sample t-test. ④ Bivariate correlation analysis was used to analyze whether the thickness, cross-sectional area, shear wave propagation velocity and postoperative time were related.
High incidence rate of knee osteoarthritis and gait analysis are important for early assessment of biomechanics. ACL injury is an ideal clinical model for studying knee osteoarthritis.~To clarify the mechanism between the biomechanical status of knee joint and the change of gait touch information, and to provide scientific basis for quantifying and evaluating the biomechanical status of knee joint in dynamic load-bearing state.