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.