Biomechanical study of elbow joint: different stages after the elbow anterior capsule injury

Purpose: Elbow contracture is a common complication post-elbow trauma, the biomechanical environment after anterior capsule injury was complex. This study aimed to use a finite element model to investigate the biomechanical environment within elbow capsule and its surrounding tissues at various stages after anterior capsule injury. Methods: A finite element model of the elbow joint, incorporating muscle activation behavior, was developed to simulate elbow flexion under normal condition (no injury) and at 2, 4, 6 and 8 weeks following anterior joint capsular injury. The model was used to analyze von Mises stress distribution and changes within the elbow tissues. Results: At no injury condition, and 2, 4, 6 and 8 weeks, the stress of the anterior articular capsule at 60° flexion were 2.62, 3.87, 4.40, 4.57 and 5.24 MPa, respectively. Under normal conditions, and at 2, and 4 weeks, the ulnar cartilage attained its peak stress at 75°. In normal conditions, the highest stress in the ulnar cartilage was 1.08 MPa, amounting to 1.02 times and 1.05 times the stress observed at 2 and 4 weeks, respectively. At 4 weeks, compared with 6 weeks, the stress of the anterior bundle at 15, 30, 45 and 60° was reduced by 11.1, 22.6, 37.3 and 36.1%, respectively. At 6 and 8 weeks, the peak stress in the posterior articular capsule reached 11.5 and 11.7 MPa, respectively, showing minimal variation. Conclusions: The results could offer theoretical basis for rehabilitation professionals in treating and preventing elbow capsule contracture.