Proximal Ulna Stress Injuries

Abstract & Commentary

Synopsis: This clinical report describes the presentation and MRI findings of a relatively uncommon and under-reported stress injury of the ulna in the dominant elbow of 7 professional baseball players.

Source: Schickendantz MS, et al. Stress injury of the proximal ulna in professional baseball players. Am J Sports Med. 2002;30:737-741.

Dr. Schickendantz and associates report the clinical, radiographic, and MRI findings of a series of 7 professional baseball players (6 pitchers, 1 catcher) with posteromedial elbow pain attributed to stress reaction of the proximal ulna and their treatment regimen. They note a variable length of time playing professionally and duration of symptoms prior to diagnosis. Common physical exam findings were pain reproduced with valgus stress testing and forced hyperextension of the elbow, and that all the athletes had an intact ulnar collateral ligament (UCL). They also noted pain to palpation and pain with percussion on the ulna. Plane radiographs were normal, so that the diagnosis was confirmed with MRI.

Dr. Ho, their radiologist, described consistent findings in the 7 cases: poorly defined patchy areas of low signal intensity in the proximal posteromedial olecranon, continuous with the cortex seen on all of the T-1 weighted images. All STIR images showed areas of high signal intensity in the posteromedial olecranon. These findings are consistent with bone edema and hyperemia. Also seen were focal linear areas of intermediate signal through the cortex and subjacent bone of the articular surface on the proximal ulna, surrounded by the poorly defined bone edema.

All players healed with nonoperative treatment, and Schickendantz et al used MRI to follow these players until return to play. Six of the players were contacted at an average of 4 years (range, 2-7 years) and were still playing professionally, while the seventh player could not be located after being traded and his playing status was unknown.

Comment by Marc R. Safran, MD

Proximal stress fractures of the proximal ulna have been described in the literature. The pathomechanics involved have also been described, though more thoroughly within the Japanese literature. Valgus extension overload and stress fractures of the proximal ulna certainly are known to occur in the professional and amateur baseball pitcher and are thought to be part of a continuum. This report is important to remind clinicians of this relatively uncommon clinical entity in the throwing athlete. Theoretically, with continued throwing, the stress reaction described in this paper may become a stress fracture of the proximal ulna, though no case in this series progressed, nor are any cases in the literature helpful in confirming this proposed natural history.

Schickendantz et al describe the clinical presentation, examination, and MRI findings of this uncommon problem. They note that the UCL was intact clinically and by MRI, though they have no objective confirmation, such as stress radiographs. However, it is well known that asymptomatic professional baseball pitchers have increased valgus laxity. Thus a lax, but intact UCL, may play a role in the pathophysiology of this injury, though this information is not obtainable from this series.

Further, Schickendantz et al used the MRI to follow the players until they returned to play. The bony edema did decrease, but not necessarily completely prior to becoming asymptomatic and returning to play. It would have been interesting to see if the radiographs revealed a stress fracture several weeks after presentation as may occur with bony resorption around a stress fracture. Further, having radiographs at final follow-up would also be helpful to see if this injury completely healed. This is important because stress fractures of the proximal ulna have a propensity to develop a nonunion if return to play is too soon, and these nonunions may not always be symptomatic.

The missing information not withstanding, this manuscript highlights an underreported problem that the clinician caring for throwing athletes should keep in mind when evaluating posteromedial elbow pain.

Dr. Safran, Co-Director, Sports Medicine, Associate Professor, UCSF Department of Orthopaedic Surgery, San Francisco, CA, is Associate Editor of Sports Medicine Reports.