Abstract
PurposeThe purpose of this study was to assess the reliability of a new objective measurement tool to measure the valgus stress laxity of the ulnar collateral ligament (UCL) of the elbow, the “Elbow Tester”. The anterior oblique portion of the ulnar collateral ligament (UCL) of the elbow is the primary static restraint to valgus stress during the overhead throwing motion. The main research question was if the “Elbow Tester” that we have developed was reliable and reproducible for further use in research and daily practice.MethodsThree different examiners tested both elbows of 11 volunteers for UCL laxity. Each elbow was tested 5 times using a standard 2 Nm valgus load, and 3 times using a manual maximum valgus load. One examiner tested the volunteers again 1 week later. The outcomes of elbow valgus laxity were compared between examiners. The intraobserver reliability was assessed using an intraclass correlation coefficient (ICC) and interobserver reliability was also assessed with a mixed model repeated ANOVA test.ResultsThe device demonstrated a high level of intraobserver reliability with both the 2 Nm valgus force and manual maximum valgus force, using a minimum of three trials as determined by an ICC > 0.9 for all examiners. The interobserver reliability was moderate using the 2 Nm valgus load with an ICC value of 0.72 and significant different outcomes of elbow valgus laxity amongst examiners (p < 0.01). A high interobserver reliability (ICC value of 0.90) was observed using manual maximum valgus force and no differences between outcomes (p > 0.53).ConclusionThe noninvasive valgus elbow tester demonstrates high interobserver and intraobserver reliability using manual maximum valgus force and can be used for further research and daily practice.
Highlights
The anterior bundle of the ulnar collateral ligament (UCL) is commonly referenced to as the primary restraint to valgus stress of the elbow between 30° and 120° of elbow flexion [1]
Intraobserver reliability The intraclass correlation coefficient (ICC) value for each examiner was determined for the 5 trials of a 2 Nm valgus load
The ICC values for all three examiners were higher than 0.95, which indicates a high level of reliability across the 2 Nm trials using 5 attempts
Summary
The anterior bundle of the ulnar collateral ligament (UCL) is commonly referenced to as the primary restraint to valgus stress of the elbow between 30° and 120° of elbow flexion [1]. Detecting actual UCL insufficiency from sports-related increased valgus laxity is challenging, even for an experienced specialist Provocative tests such as the manual valgus stress test, moving valgus stress test, and milking maneuver help recreate symptoms, and can be non-specific, and influenced by other diagnoses such as flexor-pronator strains, intraarticular lesions, medial epicondylar apophysitis, and stress fractures [2]. Conway and Thompson both demonstrated a high specificity in positive stress radiographs with asymmetric joint line opening of 2 or more mm [7, 17] Disadvantages of this imaging technique are that it requires bilateral elbow radiographs to detect a subtle asymmetric joint opening and that it is subject to a significant interobserver and intraobserver measurement error [18]
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