Effects Of The Integrity Of Medial Collateral Ligament On The Stability Of Elbow Joint

Objective To simulate the clinical comminuted radial head fracture and medial collateral ligament(MCL) injury, after excision of the radial head and release of medial collateral ligament, the valgus stability of the elbow was evaluated after medial collateral ligament reconstruction in cadaver elbows. Methods Twelve fresh human cadaveric elbow were dissected to establish the specimens with elbow joint and ligaments. Under two-newton-meter valgus torque, and at 0,30,60,90,120 degrees of flexion with the forearm in supination, the valgus elbow laxity was quantified:(1)in intact, (2)after excision of the radial head, (3)after release of the medial collateral ligament, (4)after excision of the radial head together with release of the medial collateral ligament, (5)after radial head replacement, (6)after medial collateral ligament reconstruction, (7) after radial head replacement together with medial collateral ligament reconstruction. All analysis was performed with use of SPSS 14.0 software. Results The least valgus laxity was seen in the intact state(3.0°±0.7°)and its stability was the best. The laxity of resection of the radial head increased to 6.0°±0.8°. The laxity of release of the medial collateral ligament(8.8°±1.1°) was more than that of the resection of the radial head(P<0.001). The greatest laxity was observed after release of the medial collateral ligament together with resection of the radial head(15.4°±1.8°) so its stability was the worst. The laxity of the following implant of the radial head decreased to 10.8°±0.9°, but its stability was not so as the radial head itself(P=0.004). The radial head replacement restored an average of 69.7% of the stability of the intact radial head. The laxity of the medial collateral ligament reconstruction(7.0°±1.1°) was as much as that of the intact ligament and the reconstruction restored 89.4% of the stability of the intact medial collateral ligament. The laxity of the radial head replacement together with medial collateral ligament reconstruction became less(5.3°±0.6°) and it restored an average of 81.5% of the stability of the intact elbow. Conclusions This study showed that the medial collateral ligament was the primary valgus stabilizer of the elbow and the radial head was a secondary constraint to resist valgus laxity. If both thesestructures were removed, the elbow was grossly unstable and dislocates or subluxes with applied stress. Both the Medial collateral ligament reconstruction and the radial head replacement could restore the stability of elbow. However, the reconstruction of the medial collateral ligament was more important than the replacement of the radial head.