Locked Plating of the Proximal Humerus Using an Endosteal Implant

Purpose: To report on the use of a supplemental medial endosteal implant to prevent varus collapse and screw cutout in proximal humerus fractures treated with a laterally placed locking plate. Methods: Twenty-seven patients meeting study inclusion criteria were included in the study. Follow-up averaged 63.1 weeks (minimum 37 weeks and maximum 120 weeks). All patients were either older than 70 years or had sustained a proximal humerus fracture with medial comminution. Using the anterolateral acromial approach, a proximal humeral locking plate augmented with a medial endosteal implant (fibular allograft in 23 patients and semitubular plate in 4 patients) was used for fixation. Intraoperative fluoroscopic images and the most recent follow-up radiographs were used to measure the head–shaft angle and loss of height between the implant and the articular surface. Results: Only 1 of 27 patients had significant loss of reduction with collapse of the fracture into varus (4.2 mm change). Ninety-six percent of patients maintained their original reduction with an average loss of height of 1.2 mm and an average change in shaft–head angle of 2.2 degrees. There were no implant failures or screw perforations of the articular surface and no radiographic or clinical evidence of AVN. Conclusions: Use of a medial endosteal implant as a supplement to a lateral locking plate is effective in maintaining operative reduction, preventing varus collapse, and implant failure in fractures with medial comminution and/or poor bone quality. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.