Posterior sternoclavicular joint injuries in skeletally immature patients.

BACKGROUND: Posterior injuries to the sternoclavicular (SC) joint are uncommon. In the skeletally immature (SI) population, these injuries have been described as either dislocations of the SC joint or fractures of the medial clavicular physis. The current literature and standardized test questions state that a posterior SC injury, in a SI patient, is more likely a physeal fracture than a SC joint dislocation. However, this injury characterization is based on case reports or small case series. The purpose of this study is to characterize posterior SC injuries in SI patients in terms of the prevalence of dislocation versus medial clavicle physeal fracture.

METHODS: A retrospective review was performed of 48 SI patients treated for posterior SC joint injuries over a 20-year period with a mean age of 15.4 years (range, 13 to 18 y). Forty patients underwent open reduction and internal fixation as their definitive treatment and 8 patients were treated exclusively with closed reduction. Patients treated operatively were utilized in determining the prevalence of SC joint dislocation versus physeal fracture.

RESULTS: All patients treated operatively underwent primary repair without reconstruction. Twenty (50%), of the 40 patients treated operatively had a true SC joint dislocation and 20 patients (50%) had a medial clavicle physeal fracture. Twenty-two (46%) of the 48 total patients had an attempted closed reduction of which only 8 (36%) were successful. Among the 14 unsuccessful closed reductions, 12 (86%) were true dislocations (P<0.001). All successful closed reductions occurred in patients within 24 hours from injury. Eleven of the 48 (23%) patients' injuries were missed on initial presentation.

CONCLUSIONS: Posterior SC joint dislocation and medial clavicular physeal fracture both occur with roughly equivalent prevalence in patients with an open medial physis. An attempted closed reduction may be more successful if performed within 24 hours after injury. Patients who fail attempts at closed reduction are more likely to have a posterior SC joint dislocation than a physeal fracture. Posterior SC joint injury may be missed in nearly 25% of patients on initial presentation.

LEVEL OF EVIDENCE: Level IV-retrospective case series.