Three-Part Fracture Dislocation and Four-Part Fracture Dislocation of the Proximal Humerus: How Different are the Glenoid Labrum and Capsular Injuries Between Them?

BackgroundAnterior fracture dislocation of the shoulder may have associated injury to the glenoid labrum and/or capsule. There is a need to look at the possible patterns of capsulo-labral injuries intra-operatively and correlate them with pre-operative radiographs and CT scans. It can enable surgeons to predict the patterns of soft-tissue injuries in a specific fracture type.MethodsPatients operated for ORIF of 3- and 4-part anterior fracture dislocation between January 2017 and December 2022 were included in the study. The following data were collected: demographic details, fracture morphology and classification on radiograph and CT scan, neurovascular injury, the subtype of anterior dislocation, and intra-operative identifiable injury to glenoid labrum and/or capsule.ResultsA total of 24 cases (mean age 40 +/- 10 years) of anterior fracture dislocation of the shoulder were included in the study and were grouped based on Neer's classification. 12 patients had 3-part anterior fracture dislocation (3-part Group) with a mean age of 34 +/- 9 years, while 12 patients had 4-part anterior fracture dislocation (4-part Group) with a mean age of 46 +/- 7 years (p = 0.001). 10 out of 12 patients in the 3-part Group had the subcoracoid position of the dislocated head, whereas the head was present in 9 out of 12 patients of the 4-part Group at the preglenoid position (p = 0.003). The head position was at a mean distance of 1.85 cm from the anterior glenoid rim in the 4-part Group, whereas the head was engaged at the anterior rim of the glenoid in the 3-part Group. The medial metaphyseal beak was present in 11 out of 12 patients in the 3-part Group, whereas it was absent in all the cases of the 4-part Group (p = 0.001). 92% of the included patients in our study had capsulo-labral injury. 11 out of 12 patients in the 3-part Group had labral injury compared to 10 out of 12 patients in the 4-part Group with severe capsular stripping (p = 0.001).ConclusionThe 3-part fracture dislocation with radiological findings such as the long medial metaphyseal beak and subcoracoid position of the dislocated head had a strong association with a glenoid labral injury, whereas the 4-part fracture dislocation type had a widely displaced preglenoid position of the dislocated head with an absent metaphyseal beak and had a strong association with a capsular type of soft-tissue injury.Level of EvidenceIII.