Medial Olecranon Osteotomy and UCL Strain
Abstract & Commentary
Synopsis: This laboratory study showed no statistical increase in strain in the anterior portion of the ulnar collateral ligament of the elbow with removal of up to 8 mm of bone from the medial olecranon.
Source: Andrews JR, et al. Relationship of ulnar collateral ligament strain to amount of medial olecranon osteotomy. Am J Sports Med. 2001;29(6):716-721.
Andrews and associates at the American Sports Medicine Institute in Birmingham, Ala, have previously reported that some athletes undergoing surgery for valgus extension overload syndrome (VEOS) not uncommonly require subsequent reconstruction of the ulnar collateral ligament (UCL). Because of this clinical impression, Andrews et al performed this study to determine if excision of part of the medial olecranon results in increased strain to the ulnar collateral ligament, to determine if this was the cause of UCL failure and need for reconstruction.
Andrews et al placed a DVRT (Microstrain, Inc, Burlington, Vt) to determine strain in the anterior bundle of the ulnar collateral ligament in 5 cadavers. The strain was assessed with varying loads and varying elbow flexion angles between 50 and 100° of flexion. Strain in the UCL was recorded in response to valgus stress with the medial olecranon intact, and after removing bone in 2 mm increments up to 8 mm at each flexion angle. After 8 mm of medial olecranon was removed, the proximal 5 mm was also removed from the olecranon as well to serve as a worst-case scenario for the treatment of VEOS. Lastly, the strain to failure of the anterior bundle of the UCL with the elbow at 90° of flexion was determined.
Andrews et al found there were no statistically significant differences in UCL strain with increasing bone removal. The greatest differences in UCL change were with the elbow at 50° of flexion.
Comment by Marc R. Safran, MD
The true pathophysiology and cause of elbow symptoms in baseball pitchers remains controversial. Laxity of the UCL may not be the "essential lesion" as evidenced by the reports of ball players continuing to pitch despite significant laxity and many pitchers undergoing UCL reconstruction despite clinical examinations that do not reveal significant valgus laxity. Nonetheless, it is clinically evident that many overhead athletes that undergo surgery for posterior elbow symptoms due to VEOS, who have no history of medial elbow problems, do eventually develop complaints related to UCL insufficiency. Two possible explanations may be an increased strain in the UCL due to removal of the medial olecranon bone that may be serving as a secondary restraint, or due to an unmasking of an already insufficient UCL.
Andrews et al did not find a statistically significant increase in strain within the anterior bundle of the UCL with sequential removal of bone from the medial olecranon. Although they did not identify a statistically significant increase, this does not mean that no correlation exists. There clearly appears to be a trend of increasing strain within the UCL with increasing loads and increasing removal of bone from the medial olecranon. There were large standard deviations from the average for the strains recorded and the sample size was small. An increase in sample size alone may prove these trends to be significant. Further, some of the average strains decreased in the mid range of bone removal. This paradoxical finding suggests a need for knowing the reproducibility of the methodology. This study provides a good framework for future studies in this area to evaluate the primary and secondary restraints to the UCL.
It is important to stress that despite the results of this study, removing minimal bone from the olecranon is probably the most reasonable approach in the management of overhead athletes with VEOS.
Dr. Safran, Co-Director, Sports Medicine, Associate Professor, UCSF Department of Orthopaedic Surgery, San Francisco, CA, is Associate Editor of Sports Medicine Reports.
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