Active Motion Laboratory Test Apparatus for Evaluation of Total Elbow Prostheses.

PURPOSE: The goal of this study was to develop a dynamic elbow testing apparatus that reproduces active joint motion at different shoulder positions to quantify the capabilities of total elbow arthroplasty designs.

METHODS: We designed a testing apparatus to create active cyclic elbow joint motion in human cadaveric and sawbones composite upper extremities. Two pneumatic actuators recreated humerus-originating muscles while rubber bands simulated forearm muscle action. Arthroplasty durability was quantified through laxity assessment at predetermined cyclic loading intervals.

RESULTS: Humeral forces were recorded in three specimens to generate active elbow motion at different degrees of shoulder abduction. The laxity in varus and valgus was measured as deflection between two fixed markers.

CONCLUSIONS: In vitro simulation of elbow biomechanics through active cyclic elbow motion at different degrees of shoulder abduction may characterize in vivo performance of total elbow arthroplasty.

CLINICAL RELEVANCE: Quantifying total elbow arthroplasty stability after cyclic loading in different shoulder positions may assist preclinical evaluation of arthroplasty designs.