Radiographic Assessment of Medial Elbow Stability.

Abstract

Diagnosing simple valgus instability of the elbow currently involves time and cost-intensive imaging modalities such as MRI or MRA. Previous studies have demonstrated that stress radiography represents an alternative diagnostic tool for such conditions. The aim of this study was to investigate if standardized valgus stress radiography can identify soft-tissue lesions of the medial elbow. A telos stress device (telos GAIII/E; telos Arzt- und Krankenhausbedarf GmbH; Woelfersheim-Bernstadt; Germany) was used to apply 50 N of valgus stress to six cadaveric elbows during static radiographic imaging. Forearm flexor and extensor tendons were loaded with 25 N and 20 N respectively. Ulnohumeral joint spaces [mm] were measured with the joint in the intact state (M1), after transection of the medial collateral ligament (M2) and after release of the common flexor tendon (M3). Imaging was repeated in 0°, 30° and 60° flexion with the forearm in neutral rotation, supination and pronation in each position. Mean joint gapping was increased in all groups representing ligament- and/or tendon-deficient joint conditions compared to the intact (stressed) state (group M1). The absolute difference in ulnohumeral joint gapping after common flexor tendon transection compared to the uninjured state was statistically significant (p<0.05) in all positions but not in 30° flexion and supination. Medial joint laxity was greater in 60° than 0° or 30° flexion. Joint spaces were greater in pronation and neutral rotation compared to supination. Telos stress radiographic imaging can be used to detect large ligamentous injuries at the medial elbow. Dynamic joint stabilization might affect the detection of MCL injuries. Stress radiographic imaging at the elbow should involve examination of the joint at flexion angles of 60°.