Poster 237. Clinical Characteristics and Diagnostic Accuracy of First Rib Stress Fractures in Baseball Players: A Comparative Study with Non-fracture Cases
Year: 2026
Type: article
Study design: Observational Study
Abstract: Objective: First rib stress fractures are a relatively rare cause of shoulder pain in baseball players, which are sometimes overlooked. Although several case reports have been published, there have been limited studies on their clinical characteristics and distinction from other causes of shoulder pain. Additionally, the accuracy of diagnosing a first rib stress fracture with plain radiographs is unclear. The purpose of this study was to compare clinical features of first rib stress fractures with those of baseball players presenting with shoulder pain without fracture, and to evaluate how accurately they can be diagnosed on initial radiographs. We hypothesized that first rib stress fractures present with distinct patterns, particularly posterior scapular pain during batting, and that they are often underdiagnosed despite being visible on radiographs. Methods: We retrospectively collected baseball players who visited our institute complaining of shoulder or scapular pain between 2013 and 2019. Patients without radiographs were excluded. All available imaging studies, including initial and follow-up radiographs and CT when performed, were retrospectively evaluated. All confirmed first rib stress fractures were assigned to the fracture group, while controls were randomly selected patients with baseball players with shoulder or scapula pain without fracture. Clinical variables included age, sex, affected side, playing position, pain location, and pain-inducing activity. Pain location was determined from medical records. 'Shoulder pain' was defined as pain localized around the proximal humerus, and 'scapular pain' as pain in the posterior scapular region. Diagnostic timing was categorized as fracture identified at the initial visit, diagnosed at follow-up, or missed. Imaging modalities (radiographs, CT, or follow-up radiographs) were also documented. Two orthopaedic surgeons independently reviewed all initial radiographs. Diagnostic accuracy was evaluated in terms of sensitivity, specificity, PPV, NPV, and overall accuracy. Interobserver agreement was calculated with Cohen's κ. Statistical analysis: Group comparisons used Fisher's exact test with Bonferroni correction where appropriate. Significance was set at p < 0.05. Results: Epidemiology: From 2013 to 2019, 2,285 baseball players with shoulder or scapular pain were reviewed. After excluding 190 without radiographs, 2,095 shoulders were analyzed (mean age 17 ± 7 years; 2,030 males, 65 females). Thirty-two shoulders (1.5%, all male, mean age 16 ± 2 years) were diagnosed with first rib stress fractures, while 51 shoulders without fracture (all male, mean age 17 ± 6 years) were randomly selected from the remaining non-fracture cases and served as controls. There were no significant differences in baseline characteristics between groups (Figure 1 and 2).Pain location: Posterior scapular pain predominated in fractures (26/32, 81%), whereas shoulder pain was uncommon (2/32, 6%). In contrast, controls most often presented with anterior-only or combined anterior-posterior shoulder pain (45/51, 88%). Posterior scapular pain was strongly associated with fractures (p < 0.001), yielding a sensitivity of 81% and specificity of 88% (PPV 79%, NPV 83%) (Figure 3).Pain-inducing activity: Batting was the most frequent activity in fractures (13/32, 41%), followed by pitching (5/32, 16%), whereas pitching predominated in controls (31/51, 61%, p < 0.001). Nearly half of fractures occurred during batting, reflecting rib cage stress distinct from pitching-related shoulder disorders. Diagnostic accuracy in clinical practice: Of 32 fracture cases, 15 (47%) were diagnosed at the initial visit (12 by radiographs, 3 by CT), 4 (12%) at follow-up, and 13 (41%) were missed. Retrospective review showed 29 of 32 fractures (91%) were visible on initial radiographs, while 2 cases (6%) required CT and 1 (3%) follow-up radiographs, suggesting most were overlooked rather than radiographically occult. This finding highlights the supplementary role of CT in selected cases (Figure 4). Radiograph performance against reference standard: Examiner 1 demonstrated a sensitivity of 91%, specificity of 94%, PPV of 91%, NPV of 94%, and accuracy of 93%. Examiner 2 showed a sensitivity of 91%, specificity of 98%, PPV of 97%, NPV of 94%, and accuracy of 95%. Interobserver agreement was excellent (κ = 0.90). Conclusions: First rib stress fractures accounted for 1.5% of baseball players with shoulder pain, occurring exclusively in adolescent males. Posterior scapular pain, particularly posterior-only, was highly characteristic and demonstrated strong specificity, whereas anterior pain predominated in baseball shoulder. Batting was the leading mechanism of injury, emphasizing the load transmitted to the rib cage during swing motion. Although nearly half of fractures were initially missed, careful review of radiographs detected most cases with high accuracy and excellent interobserver reliability. CT may be considered in selected cases with persistent suspicion despite negative or equivocal radiographs. Recognition of these patterns may improve diagnostic precision, reduce misclassification, and support timely management for safe return to play in young athletes.
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $1,500
OpenAlex ID: W7204773645