Terrible triad elbow fracture-dislocation with triceps and flexor-pronator mass avulsion.

Terrible triad elbow injuries, consisting of fractures of the radial head and coronoid with ulnohumeral dislocation, are challenging to treat. They require a comprehensive understanding of the complex anatomy of the elbow to effectively treat all of the pathology and create a stable, congruent joint. The authors present a case of a terrible triad injury with avulsion of the triceps and flexor-pronator mass after a low-energy fall in a young patient. Although most terrible triad fracture-dislocations can be successfully treated with coronoid fixation, radial head fixation or replacement, and repair of the lateral collateral ligament complex, this case involved a completely circumferential injury to the elbow. The coronoid and anterior capsule were disrupted anteriorly, the radial head and lateral collateral ligament complex were disrupted laterally, the triceps was disrupted posteriorly, and the flexor-pronator mass was disrupted medially. Although the authors prefer to address most terrible triad injuries through a lateral approach, they suspected a circumferential injury preoperatively and elected to use a single posterior incision to address all of the pathology conveniently. This injury required treatment of all disrupted structures, because the elbow remained unstable until the triceps and flexor-pronator mass avulsions were ultimately repaired. With any elbow fracture-dislocation, surgeons should look for evidence of additional injuries that do not fit the commonly described patterns, because they may necessitate modifications to the treatment plan. Given the relatively common complications of stiffness and instability despite modern surgical techniques, additional injuries may further compromise functional outcomes unless they are addressed properly.