Complex varus elbow instability: a terrible triad model.

HYPOTHESIS: The terrible triad is a debilitating injury that involves elbow dislocation with injury to the lateral collateral ligament (LCL) complex, the radial head, and the coronoid process. This study investigated the role of these components in varus stability of the elbow. MATERIALS AND METHODS: We investigated the role of these components in varus stability of the elbow using 10 cadaveric fresh frozen upper extremities. The testing order allowed each of four states to be tested (intact, LCL complex deficient or repaired, radial head resected or replaced) at two flexion angles and multiple coronoid resection levels. Values for restraining load (newtons [N]) at 1.5 cm of varus displacement were obtained on a materials testing machine. RESULTS: Beyond a 50% loss of the coronoid process, neither repair of the LCL nor replacing the radial head alone resulted in a statistically significant increase in varus stability. For a loss of the coronoid process between 67-75%, repair of the LCL and replacement of the radial head showed improved stability over repair alone, or radial head replacement alone. For loss of the coronoid beyond 75%, even repair of the LCL and replacement of the radial head did not improve varus stability of the elbow. CONCLUSION: These findings provide a biomechanical basis for aggressive treatment of coronoid fractures as a component of the terrible triad injury. LEVELS OF EVIDENCE: Basic science study.

Role of the coronoid process in varus osteoarticular stability of the elbow.

The role of the coronoid process in varus osteoarticular stability of the elbow was investigated in 10 cadaveric elbows. Testing was performed at multiple flexion angles after incremental removal of the coronoid. At each flexion angle, removal of more than 50% of the coronoid produced a statistically significant decrease in the load resisting varus displacement compared with all lesser resection levels (P < .003). There was a trend for decreasing load after removal of 50% of the coronoid. The mean decrease in load across all flexion angles was 10.1%, 50.4%, and 75.4% after removal of 50%, 75%, and 100% of the coronoid, respectively. Resistance to varus displacement tended to decrease more as a percent of control at lower flexion angles than at higher flexion angles after removal of more than 50% of the coronoid. The coronoid process was found to be a key varus stabilizer in the elbow and may contribute more to elbow stability in extension than in flexion.

Intramuscular angiomatous tumors associated with periosteal changes and pain.

This case report discusses two cases in which patients present with the uncommon triad of extremity pain, focal periosteal reaction on imaging studies, and intramuscular hemangioma on pathologic examination. Both patients presented in this article were older than those previously reported in the literature. Neither patient reported complete resolution of pain following excision, although there was marked improvement.