Isolated Avulsion of the Medial Head of the Triceps Tendon: An Anatomic Study and Arthroscopic Repair in 2 Cases

Purpose: The purpose of this study was to determine the area and characteristics of the triceps tendon footprint on the olecranon, with special attention to the medial head insertion. The secondary goal was to report 2 cases of isolated avulsions of the medial head of the triceps tendon treated successfully with arthroscopic repair. Methods: Fifteen cadaveric upper extremities were examined to investigate the triceps tendon insertion, and two case reports of an arthroscopic repair technique are described. Results: In 8 specimens (53%) there was a separate insertion of the medial head of the triceps tendon on the olecranon, which was deep to the long and lateral head insertions. The mean area of the medial head insertion was 44 mm(2), and the mean area of the combined long and lateral head insertions was 115 mm(2). In 7 specimens (47%) the long, lateral, and medial heads of the triceps inserted together and had a mean area of 134 mm(2). Although the 3 heads of the triceps inserted together, the medial head tendon fiber orientation was still directed deep to the long and lateral heads. At 2 years' follow-up, both patients described no pain, had better strength, and had improved Disabilities of the Arm, Shoulder and Hand scores and Mayo Elbow Performance Scores. Conclusions: We have determined the characteristics of the distal triceps tendon footprint and the insertional orientation on the olecranon. For cases with an isolated avulsion of the medial head of the triceps tendon, an arthroscopic repair technique is described. Level of Evidence: Level IV, anatomic study and therapeutic case series.