Review Question - QID 219783

This 22-year-old sustained a right elbow dislocation with posterolateral rotatory instability, which stems from an injury to the lateral collateral ligament (LCL) complex. These ruptures most commonly occur at its origin (lateral epicondyle) on the humerus (Answer 1).

Posterolateral rotatory instability (PLRI) can arise from several etiologies, however, trauma, and specifically elbow dislocations, serve as the most common source of the condition. The diagnosis can be made clinically, with the patient continuing to report sensations of instability, most of which occur during axial loading coupled with supination and valgus stresses, a force moment commonly encountered when arising out of a chair, for example. The most common location for the LCL complex to fail is at the ligament's origin on the humerus, specifically the lateral epicondyle.

Acosta Batlle et al. reviewed the elbow anatomy and its associated pathology with the utilization of an MRI. The authors highlight the three stages of instability that can occur during elbow dislocations, which is otherwise known as the 'Circle of Hori', which begins laterally with failure of the LCL complex before progressing medially, with disruption of the anterior and posterior capsule, which is followed by failure of the medial ulnar collateral ligament. The authors conclude MRI remains the best modality to assess ligamentous injuries to the elbow.

Karbach et al. examine the anatomy, biomechanics, physical exam, and diagnostic workup associated with elbow instability. They note both traumatic, overuse, and iatrogenic causes can contribute to elbow instability. The authors note the lateral pivot shift and posterolateral rotatory drawer test to be useful in anesthetized patients, but other maneuvers that replicate commonly performed activities, namely the chair push-up test and prone push-up test exhibit high sensitivities when used in isolation and together.

Figure A represents an AP radiograph of the right elbow.

Incorrect Answers:
Answer 2: Location B represents the insertion of the LCL complex onto the crista supinatorus/supinator crest
Answer 3: Location C is the insertion of the biceps tendon onto the radial tuberosity
Answer 4: Location D represents the medial epicondyle, which is the origin of the medial ulnar collateral ligament
Answer 5: Location E is the sublime tubercle, which is the site of insertion for the medial ulnar collateral ligament