Factors that Influence Reduction Loss in Proximal Humerus Fracture Surgery.

Objectives: This study was performed to identify the risk factors for reduction loss after locking plate fixation of proximal humerus fractures.
Design: Retrospective study.
Setting: University trauma center.
Patients and Intervention: We retrospectively evaluated 252 patients who had been surgically treated for proximal humeral fractures with locking plates between January 2004 and December 2011.
Main Outcome Measurements: Charts and standardized x-rays (true anteroposterior and axillary lateral views) were used to evaluate the Neer and AO OTA fracture types, initial neck-shaft angle (NSA, varus displacement), medial comminution, postoperative NSA (reduction adequacy), medial support restoration, healing progress, reduction loss, and implant-related problems immediately after surgery and at 2 weeks, 1 month, 3 months, 6 months, 9 months, and at least 1 year after surgery. Reduction loss was defined as (1) ≥10 of angulation in any direction, (2) ≥5 mm of height loss of the humeral head from the plate, and (3) fixation failure.
Results: Reduction loss occurred in 6.7% (17 of 252) of cases; revision surgeries were performed in all cases. Univariable logistic regression analysis revealed that older age (P = 0.023), osteoporosis (P = 0.001), varus displacement (P = 0.001), medial comminution (P = 0.001), reduction adequacy (P = 0.036), and insufficient medial support (P = 0.001) had significant correlations with reduction loss.
Conclusions: Multivariable regression analysis revealed that osteoporosis (less than -2.5 bone mineral density, P = 0.015), displaced varus fracture (less than 110° of NSA, P = 0.025), medial comminution (more than 1 fragment, P = 0.018), and insufficient medial support (no cortical or screw support, P = 0.001) were independent risk factors for reduction loss in the proximal humerus fractures surgery.
Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.