- In this retrospective study, researchers evaluated stress radiographs of 79 young adults with throwing-related medial elbow pain and compared them with MRI scans
- There was no difference in joint gapping between patients without tears in the ulnar collateral ligament (UCL) and patients with full-thickness tears (1.0 vs. 1.8 mm, P = NS)
- Excess opening—the difference in joint space opening of injured versus uninjured elbow—was not significantly related to UCL injury severity
- There were no significant correlations among clinical characteristics in patients with a negative versus positive excess opening
- Considering that MRI has become the gold standard for evaluating UCL injury, stress radiographs are of limited use in the workup of throwing athletes with medial elbow pain
Valgus stress radiography has been used for more than two decades to quantify medial elbow instability. The originators of the technique reported direct correlation between the medial joint space opening of the elbow and the extent of injury to the ulnar collateral ligament (UCL).
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However, a 2014 study in The Journal of Shoulder and Elbow Surgery of 273 baseball players with UCL injuries found 31% had a negative excess opening, defined as less joint opening on the injured side than on the uninjured side. One theory about the negative excess opening is that patients may "guard" their symptomatic elbow during radiography.
PhD candidate Rik J. Molenaars, MD, and Luke S. Oh, MD, orthopaedic surgeon at the Sports Medicine Center at Massachusetts General Hospital, and colleagues recently became the first to investigate this theory. In the Journal of Shoulder and Elbow Surgery, they say they could not verify guarding as a confounding factor, but they report additional evidence that stress radiography has limited usefulness for evaluating UCL injury.
The researchers retrospectively studied 79 patients with throwing-related medial elbow pain who underwent stress radiography between 2011 and 2016 and had MRI available for review. There were 72 male baseball players, one male javelin thrower and one female softball player. The average age at radiography was 19 years (range, 14.5–25).
Joint Gapping and Excess Opening
The amount of joint gapping in injured elbows was significantly related to the severity of UCL injury on MRI. However, the group-level analysis showed no difference in joint gapping between patients without UCL tears and patients with full-thickness tears (1.0 vs. 1.8 mm, P = NS).
Excess opening—the difference in joint space opening of injured versus uninjured elbow—was not significantly related to UCL injury severity. This is important because, in the original report on using stress radiography to evaluate UCL injury, determination of the extent of the injury was based on contralateral comparison of joint opening.
Positive vs. Negative Excess Opening
A negative excess opening was observed in 16 of 74 patients (22%). There were no significant correlations among clinical characteristics in patients with a negative versus positive excess opening. Neither did any characteristics corroborate mechanical explanations for negative excess opening such as posterior osteophytes or loose bodies.
Recommendations for Clinicians
MRI is the gold standard for evaluating UCL injury. The high prevalence of negative excess opening implies stress radiographs have limited additional use in the workup of throwing athletes who have medial elbow pain. They expose patients to needless radiation and add unnecessary costs.
Learn more about the Sports Medicine Center at Mass General
Refer a patient to the Department of Orthopedics at Mass General