LAUSR

Objectives: First-rib stress fractures as a potential cause for non-specific atraumatic chronic shoulder pain in adolescent athletes. However, etiology on throwing athletes with first rib fracture have not been still unknown. The purpose of this retrospective study was to investigate characteristic clinical features and radiographic findings of patients with the first rib fracture in overhead throwing athletes. Methods: Twenty-four cases of first rib stress fracture in 23 players were studied retrospectively. We reviewed clinical features, including age, initial symptom, sports, activity related to pain, method of diagnose, method of treatment, and final follow-up. Results: We found characteristic clinical features as follows; 16.8 years (13-25), 19 dominant side injury and 5 non-dominant injury, an acute increase in pain while swinging the bat (9 cases) or pitching the ball (6 cases). Sixteen cases presented with posterior shoulder, inferior or medial border of the scapula, upper thoracic back pain. The current study showed 17 healing on average 3.8 month after conservative treatment and 7 nonunion of throwing athlete with the first rib stress fracture, (69.6%, 30.4%, respectively). Analysis on radiographs and CT revealed that the first rib stress fractures were classified into 3 types depends on direction and portion of fracture lines: Groove type, fracture line along with the subclavian artery groove; Intrascalene type, fracture line inside the middle scalene muscle insertion; and Posterior type, fracture beside to the costovertebral articulation (Figure 1 a-c). A 3-dimensional CT angiography showed that fracture line in the Groove type was consistent with the subclavian artery and fracture line in the Intrascalene type was different to the subclavian artery (Figure 2 a-f).We found 2 symptomatic cases and they had the first rib resection cause of thoracic outlet syndrome. We calculated percent availability of the first rib based on the measurements of 2 different observers. Percent availability of the shoulder and cervical spine radiographs were 46% and 97%, respectively. The Cohen’s kappa coefficient and percent agreement of the shoulder and cervical spine were 0.87, 89.4% and 0.80, 99.0%, respectively. Conclusion: We should consider the first rib stress fracture when teenage overhead athletes have posterior shoulder pain and acute onset while swinging the bat or pitching the ball. An anteroposterior radiograph of the cervical spine was available for initial diagnose. Although 70% of the patients would heal in 3 months with conservative treatments, some patients may have a symptom like thoracic outlet syndrome.