What did the study look at?
Professional baseball pitchers repeat a fast, complex overhead movement that places considerable strain on the shoulder. Teams sometimes obtain magnetic resonance imaging (MRI) of players who have no symptoms before the season, but it is unclear whether findings in a pain-free shoulder matter later on.
The authors set out to examine whether structural changes seen on preseason MRI of the asymptomatic throwing shoulder were related to later injury, surgery and placement on the injured list. Their starting hypothesis was that such changes would correlate with injury, surgery and time on the list.
How was it done?
This was a retrospective review. Preseason shoulder MRI scans of pitchers signed by a single organisation between 2005 and 2017 were assessed. Pitchers with previous shoulder or elbow surgery, time on the injured list in the previous two years, or symptoms in the six months before the scan were excluded.
- Scans were read by three independent reviewers (two orthopaedic sports medicine surgeons and one musculoskeletal radiologist) who were blinded to the player's identity and later course.
- The rotator cuff, labrum, joint capsule, biceps tendon and humeral head were evaluated.
- Injury, surgery and performance data were collected from publicly available databases; performance measures were calculated at 1, 2, 3 and 5 years after the scan.
What did it find?
Of 41 pitchers evaluated, 29 were included in the analysis; 7 were later placed on the injured list for shoulder-related reasons and 22 remained in the "healthy" group. The injured group was significantly older than the healthy group (31.9 vs 27.1 years).
- Some findings were more common in the injured group, for example labral signal change (71.4% vs 40.9%) and a posterior-superior humeral head cyst (85.7% vs 45.5%).
- However, no MRI finding significantly predicted placement on the injured list or the time spent on it.
- A partial articular-sided rotator cuff tear and intra-articular biceps tendon signal were associated with future surgery, but only one player went on to have surgery.
- Pitchers with labral signal change had higher total career pitch counts (10,034.1 vs 2,465.3).
- Pitchers with a posterior-superior humeral cyst had lower values on some strikeout measures, for example a strikeout percentage of 16.6% vs 23.2% at 2 years.
The authors' conclusion
According to the authors, although the frequency of various imaging findings differed between the injured and healthy groups, no MRI finding predicted future injured-list placement or its duration. A posterior-superior humeral cyst, a labral tear and increased capsular signal were associated with particular performance measures. The authors suggest that the posterior-superior humeral cyst may be a new imaging marker related to performance and that this should be examined in further studies.
Limitations
- The retrospective design and small number of players from one team limit statistical power.
- Some MRI findings are harder to identify than others, and reviewer bias is possible.
- Injury and surgery data came from public databases, which may limit accuracy.
- Clinical data such as strength and range of motion were not available.
- The link with surgery rests on a single player, so the authors state they cannot draw conclusions on it; the older age of the injured group may also have influenced the results.
Reference
Beletsky A, Okoroha KR, Cabarcas B, Garcia GH, Gowd AK, Meyer J, Vadhera AS, Singh H, Gürsoy S, White GM, Davidson J, Nicholson GP, Chahla J, Verma NN. (2022). Magnetic Resonance Imaging Findings of the Asymptomatic Shoulder May Impact Performance, Not Future Injury List Placement in Major League Baseball Pitchers. Arthroscopy, Sports Medicine, and Rehabilitation, 4(2), e487-e493. Licence: CC BY-NC-ND 4.0.
DOI: 10.1016/j.asmr.2021.10.029
Free full text: PubMed Central (PMC9042760)
This article summarises a published scientific paper for general information; it does not replace an examination or a personal medical assessment. Please consult your doctor about your symptoms.
