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The Effect of Radial Head Excision on Load Transmission in Female Elbows
Mark Ayzenberg, MD; Chris Williamson, MD; Dillon Arango, MD; Grigory Gershkovich, MD; James Raphael, MD
Einstein Medical Center, Philadelphia, PA
Introduction: This biomechanical study evaluated the load distribution of the elbow articulations prior to and following radial head resection. Changes in percentage of load through the medial and lateral aspects of the trochlea were measured following radial head resection in women. We hypothesized that the lack of a lateral buttress at the elbow after resection would increase valgus stress and load across the lateral ulnohumeral joint (UHJ).
Methods: Six fresh frozen female cadaver (60-90 yo) upper extremities were imaged in full extension/supination to evaluate carrying angle. Normal pressure distribution was measured across the radiocapitellar joint (RCJ), medial and lateral trochlea. Specimens were stripped of soft tissues at the arm/hand, osteotomized at the humerus and third metacarpal, and potted in Cerrobend©. Specimens were then mounted on the electromechanical device with the forearm in full supination. RCJ and UHJ articulations were exposed through standard approaches. Thin film pressure sensors were inserted into the RCJ, medial and lateral trochlea. A compression load was applied to a maximum of 200N. Following radial head resection, the specimens were loaded identically and the foces were measured. Post-resection radigraphs were obtained to evaluate change in elbow valgus under axial load.
Results: Radial head resection resulted in an alteration of the distribution of load within the UHJ. The percentage of total ulnohumeral force in the lateral trochlea increased from 31% to 84%. Medial trochlear forces decreased from 69% of total UH load (29% of total elbow load) to 16%. Valgus alignment increased under axial load following radial head resection from 17º to 22º.
Conclusion: The results of this preliminary trial support our hypothesis that radial head resection leads to abnormal loading of the elbow joint. This causes excessively increased forces and uneven load distribution at the ulnohumeral joint and leads to increased valgus alignment at the elbow. Some limitations of this study include the pressure sensors, which have some variability in their readings, and the difficulty in recreating a true axial load through the extremity. Future studies will be aimed at identifying the contribution of DRUJ and interosseous attachments to forearm mechanics following radial head resection. It would also be useful to repeat this study with a male cadaver elbows for comparison.
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