[The collateral ligaments of the elbow joint: their functional anatomy with special reference to the pathology and treatment of post-traumatic stiff elbow].

Factors which cause stiff elbow were investigated both experimentally and clinically. Since a thickened and shortened medial collateral ligament is often seen in stiff elbow, then changes in the length of the medial collateral ligament (MCL) and in the length of the lateral collateral ligament (LCL) were investigated in cadaver elbow specimens, and correlated with the observed range of motion. The MCL was divided into five bundles, and the LCL into three bundles. The length changes during flexion and extension of the elbow joint were measured, and the length change pattern was found to be different from bundle to bundle. The lengths of the LCL and the anterior oblique ligament (AOL) of the MCL changed little during elbow flexion. On the other hand, the length of the posterior oblique ligament (POL) of the MCL considerably increased when the elbow joint was flexed. The more posterior the bundle was, the larger the change in length that was observed. Because the origin of the POL is far distant from the axis of motion, it was suspected that a shortening in the POL was one of the most important pathologic changes in stiff elbow. The results of the biomechanic study were applied to a subsequent clinical study. Scar formation or ectopic ossification on the medial and/or posterior parts of the elbow joint was observed in 38 of 43 cases at surgery. These pathologic regions were resected, including the scarred POL. The intra-operative findings revealed that the major restraints in stiff elbow were the medial and/or posterior parts of the elbow. The importance of the shortened POL in the clinical pathology of stiff elbow was clearly demonstrated.