Review Question - QID 9107

Figure A demonstrates a fracture of the anteromedial coronoid. Patients with this injury pattern will have feelings of instability with the gravity-assisted varus stress test.

Varus posteromedial rotatory instability (VPMRI) of the elbow is caused by a varus and posteromedial rotation force, resulting in rupture of the lateral collateral ligament (LCL) from its humeral origin. The medial coronoid process is subsequently forced against the medial trochlea, which results in fracture of the anteromedial portion. The most sensitive test is the gravity-assisted varus stress test. The arm is abducted to 90° and the patient is asked to flex and extend the elbow. The test is positive for pain, grinding, or instability during range of motion, as the ulnohumeral joint is closed medially by the lack of the buttress from the anteromedial coronoid. Treatment involves surgically addressing the anteromedial facet of the coronoid and repairing the LCL.

Steinmann performed a review of coronoid process fractures. He reports that with an anteromedial coronoid fracture, the anteroposterior (AP) radiograph of the elbow will demonstrate progressive narrowing of the joint space from lateral to medial. They conclude that an important determinant of stability is the involvement of the sublime tubercle (insertion point of the MCL). When the sublime tubercle is involved, medial elbow instability is likely.

Doornberg et al. performed a retrospective review of coronoid fracture patterns. They found that large fractures of the coronoid were involved with anterior and posterior olecranon fracture/dislocations, small transverse fractures were involved with terrible triad injuries, and anteromedial facet fractures were associated with VPMRI.

Doornberg et al. performed a retrospective review of patients with fracture of the anteromedial facet of the coronoid. They report that if the fracture is not specifically treated, patients ultimately developed arthrosis. They report that the coronoid fracture may be secured with a plate, screw, or sutures. They conclude that secure fixation of the coronoid usually restores good elbow function.

Figure A is an AP radiograph of the elbow demonstrating a fracture of the anteromedial facet of the coronoid. Illustration A is a fluoroscopic stress view demonstrating ulnohumeral instability due to an associated LCL injury. Illustration B is an AP radiograph demonstrating plate and screw fixation of the coronoid and suture anchor repair of the LCL.

Incorrect Answers:
Answer 1: The lateral pivot shift test is performed with the patient supine with the affected arm overhead. The forearm is supinated and valgus stress is applied while flexing the elbow. Subluxation constitutes a positive finding and is seen in valgus posterolateral rotatory instability of the elbow.
Answer 2: The milking maneuver is performed by creating valgus stress by pulling the patient's thumb with the forearm supinated and elbow flexed to 90°. Subluxation constitutes a positive finding and is seen in valgus posterolateral rotatory instability of the elbow.
Answer 3: The chair rise test is performed by asking the patient to push off from a seated position in a chair. Subluxation when transitioning to elbow extension constitutes a positive finding and is seen in valgus posterolateral rotatory instability of the elbow.
Answer 4: The posterior drawer test is performed with the patient in a seated position with the elbow flexed to 90°. The clinician stabilizes the humerus and gives a superior and inferior force to the forearm. Subluxation constitutes a positive finding and is seen in valgus posterolateral rotatory instability of the elbow.