Differences in Rupture Patterns and Associated Lesions Related to Traumatic Distal Triceps Tendon Rupture Between Outstretched Hand and Direct Injuries
Authors: Lee Ji Ho , Ahn Kee Baek , Kwon Kwi Ryun , Kim Kyung Chul , Rhyou In Hyeok 
Published: November 2020

Abstract

Background
Traumatic distal triceps tendon rupture results in substantial disability in the absence of an appropriate diagnosis and treatment. To the best of our knowledge, differences in the degree of injury according to the injury mechanisms and associated lesions are not well known.

Questions/purposes
In this study, we asked: (1) What differences are seen in triceps tear patterns between indirect injuries (fall on an outstretched hand) and direct injuries? (2) What are the associated elbow and soft tissue injuries seen in indirect and direct triceps ruptures?

Methods
Between 2006 and 2017, one center treated 73 elbows of 72 patients for distal triceps tendon rupture. Of those, 70% (51 of 73 elbows) was excluded from this study; 8% (6 of 73) were related to systemic diseases, 59% (43 of 73) sustained open injuries, and 3% (2 of 73) were related to local steroid injections. We retrospectively collected data on traumatic distal triceps tendon rupture in 30% (22 of 73) of elbows at a single trauma center during a 10-year period. A fall on an outstretched hand was the cause of injury in 15 patients and direct blow by object or contusion were the cause in seven. MRI and surgery were performed in all patients. Traumatic distal triceps tendon rupture was classified by the Giannicola method, which is classified according to the depth and degree of the lesion based on MRI and surgical findings. Associated fractures and bone contusions on MRI were characterized. Ligament injuries on MRI was divided into partial and complete rupture. Agreement between the MRI and intraoperative findings for the presence of a traumatic distal triceps tendon rupture was perfect, and the Giannicola classification of traumatic distal triceps tendon rupture was good (kappa = 0.713).

Results
In the indirect injury group (fall on an outstretched hand), 15 of 15 patients had injuries that involved only the tendinous portion of the distal triceps, but these injuries were not full-thickness tears, whereas in the direct injury group, three of seven patients had a full-thickness rupture (odds ratio [OR] 1.75 [95% CI 0.92 to 3.32]; p = 0.02). The direct injury group had no associated ligamentous injuries while 14 of 15 patients with indirect injuries had ligamentous injuries (OR 0.13 [95% CI 0.02 to 0.78]; p < 0.001; associated injuries in the indirect group: anterior medial collateral ligament [14 of 15], posterior medial collateral ligament [7 of 15], and lateral collateral ligament complex [2 of 15]). Similarly, one of seven patients in the direct injury group had a bone injury (capitellar contusion), whereas 15 of 15 patients with indirect ruptures had associated fractures or bone contusions (OR 16.0 [95% CI 2.4 to 106.7]; p < 0.001).

Conclusion
A fall on an outstretched hand may result in an injury mostly to the lateral and long head of distal triceps tendon and an intact medial head tendon; however, direct injuries can involve full-thickness ruptures. Although a traumatic distal triceps tendon rupture occurs after a fall on an outstretched hand, radial neck, capitellar, and medial collateral ligament injury can occur because of valgus load and remnant extensor mechanisms. Based on our finding, the clinician encountering a distal triceps tendon rupture due to a fall on an outstretched hand should be aware of the possibility of remaining elbow extensor mechanism by intact medial head tendon portion, and associated injuries, which may induce latent complications.

Level of Evidence
Level III, prognostic study.