Objective To investigate the effect of complete anterior bundle of medial collateral ligament (MCL) on the valgus stability of the elbow after reconstruction and to assess the efficacy of artificial tendon and interference screw in reconstruction the anterior bundle of MCL. Methods The bone-tendon of the elbow were made in 12 adult upper limb specimens. There were 8 males and 4 females, left side and right side in half. Using biomechanic ways and pressure sensitive film, the valgus laxity, the stress area of the humeroulnar joint, and the intra-articular pressure were measured in integrated anterior bundle of MCL (control group, n=12) and reconstructed anterior bundle of MCL with artificial tendon and interference screw (experimental group, n=12) in elbow flexion of 0, 30, 60, and 90°. Results There was no significant difference in the valgus laxity within group and between groups in different flexion degrees (P gt; 0.05). No significant difference was found in the intra-articular pressure in elbow flexion of 30, 60, and 90° within group and between groups (P gt; 0.05) except in elbow flexion of 0° (P lt; 0.05). The stress area of the humeroulnar joint in 0° flexion was significantly larger than that in 30, 60, and 90° flexion in the control group (P lt; 0.05), but no significant difference was found within group and between groups in the other flexion degrees (P gt; 0.05). Conclusion The anterior bundle of MCL has important significance for maintaining the valgus stability of the elbow, after reconstructing the anterior bundle by using artificial tendon and interference screw, the medial stability of elbow can be recovered immediately.
Objective To investigate whether or not posterolateral rotatory instabil ity of the elbow is due to type-I and type-II coronoid process fracture together with anterior bundle of medial collateral l igament (AMCL) injury so as to provide a theoretic basis for its cl inical treatment. Methods Ten fresh-frozen upper extremities were collected from cadavera which was donated voluntarily with no evidence of fracture, dislocation, osteoarthritis, mechanical injury of the surrounding l igament and joint capsule. They included 9 males and 1 female with an average age of 25.1 years (range, 19-40 years), including 3 cases at left sides and 7 cases at right sides. All specimens were transected at the upper midhumeral and carpal levels preserving the distal radioulnar joints to get the bone-l igament specimens. An axial load of 100 N compressing the elbow joint was appl ied along the shaft of the forearm in the sagittal plane through the biomechanical study system. The load-displacement plot was measured and analyzed at elbow flexion of 90, 60, and 45° and under four conditions (intact elbow, type-I coronoid process fracture, type-I coronoid process fracture with AMCL deficient, and type-II coronoid process fractures with AMCL deficient). Results The posterior displacements were maximum at 90° elbow flexion. Hence, the results at 90° elbow flexion were analyzed: under condition of intact elbows, the posterior displacement was the smallest (2.17 ± 0.42) mm and the posterolateral rotatory stabil ity was the greatest; under condition of type-I coronoid process fracture, the posterior displacement was (2.20 ± 0.41) mm, showing no significant difference compared with that of the intact elbow (P gt; 0.05); under condition of type-I coronoid process fracture with AMCL deficient, the posterior displacement was (2.31 ± 0.34) mm, showing no significant difference compared with that of intact elbow (P gt; 0.05); and under condition of type-II coronoid process fracture with AMCL deficient, the posterior displacement was (2.65 ± 0.38) mm, showing a significant difference compared with that of intact elbow (P lt; 0.05). There was no macroscopic ulnohumeral dislocation or radial head dislocation during the experiment. Conclusion An simple type-I coronoid process fracture or with AMCL deficient would not cause posterolateral rotatory instabil ity of elbow and may not need to be repaired. But type-II coronoid process fractures with AMCL deficient can cause posterolateral rotatory instabil ity of elbow, so the coronoid process and the AMCL should be repaired or reconstructed to restore posterolateral rotatory stabil ity as well as valgus stabil ity.