Introduction: We compared two arthroscopic repair techniques to an intact shoulder using a biomechanical model of anterior shoulder dislocation with an anterior glenoid rim fracture (Ideberg IA fracture). We hypothesized that transosseous repair is sufficient to effectively stabilize the glenoid fracture. The primary objective was to define the mechanical properties of transosseous repair of an Ideberg IA fracture relative to an intact shoulder (control group). The secondary objective was to determine the contribution of supplemental anteroposterior screw fixation of the bone fragment.
Materials and methods: Fifteen fresh cadaver shoulders were divided into two groups: 5 specimens in the control group and 10 in the fracture fixation group, with sequential performance of transosseous repair followed by transosseous repair+screw fixation. A fracture at the inferior portion involving more than 30% of the glenoid's surface area was made.
Results: The load to failure was 457 N in the control group, 277 N in the transosseous repair group and 325 N in the transosseous repair+screw fixation group. The stiffness of the constructs was 26.2N/mm for the control group, 14.6N/mm for transosseous repair and 24.6N/mm for transosseous repair+screw fixation. The difference between the two repair techniques was significant for the load to failure (p=0.02) and stiffness (p=0.001).
Discussion/conclusion: This study showed that transosseous repair restores the shoulder's anatomy but not the mechanical strength of the native glenoid. Adding screw fixation significantly improves the construct.
Level of evidence: IV, basic science study.
Keywords: Biomechanics; Glenoid fracture; Model; Osteosynthesis; Shoulder.
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