[A special type of triple injury of superior shoulder suspensory complex-lateral segment floating clavicle].

Objective: To investigate the clinical characteristics and injury mechanisms of lateral segment floating clavicle (LSFC), and to establish a comprehensive classification system for this specific triple injury of the superior shoulder suspensory complex (SSSC), so as to provide a reference for clinical diagnosis and treatment. Methods: A retrospective analysis was performed on 354 patients with midclavicular fractures who underwent surgical treatment between January 2021 and December 2024. Among them, 11 patients met the diagnostic criteria for LSFC, defined as a combination of midclavicular fracture, ipsilateral coracoid process fracture or coracoclavicular ligament rupture, and ipsilateral acromioclavicular ligament rupture, distal clavicular fracture, or acromial fracture. There were 9 males and 2 females, with an age range of 21-53 years (mean, 39.3 years). LSFC was classified into two main types: Type Ⅰ was characterized by coracoclavicular ligament rupture, and type Ⅱ by coracoid process fracture. According to the injury pattern at the acromioclavicular joint-distal clavicle complex, each type was further subdivided into three subtypes: subtype a (acromioclavicular ligament rupture or acromioclavicular joint dislocation), subtype b (distal clavicular fracture), and subtype c (acromial fracture). Of the 11 patients, 4 were classified as type Ⅰa, 5 as type Ⅱa, and 2 as type Ⅱb. All patients underwent open reduction and internal fixation. Missed diagnosis occurred in 3 cases (27.3%), intraoperative revision of the surgical plan was required in 1 case, and postoperative delayed diagnosis was found in 2 cases during follow-up, with 1 patient undergoing reoperation. Results: All 11 LSFC patients were followed up 13-26 months (mean, 17.8 months). Bony union was achieved in all fractures at last follow-up. A total of 7 complications were noted: 3 cases of acromioclavicular joint subluxation, 3 cases of periprosthetic osteolysis around the clavicular hook plate, and 1 case of wire breakage. The incidence of ipsilateral multiple rib fractures in LSFC patients was 45.5% (5/11), which was significantly higher than that in patients with isolated midclavicular fractures (1.7%, 6/343) ( Conclusion: LSFC is mostly caused by high-energy trauma, with a high rate of missed diagnosis and frequent associated injuries. In particular, ipsilateral multiple rib fractures are a highly suggestive sign of LSFC. The classification system proposed in this study summarizes the characteristics of this triple injury of SSSC, which is conducive to improving clinicians' understanding of the injury and reducing the rate of missed diagnosis.