gms | German Medical Science

Objectives: This study aimed to determine if the ratio of cortical thickness to shaft diameter of the humerus, as measured on a simple anterior-posterior shoulder radiograph, is associated with surgical fixation failure.

Methods: 64 consecutive fractures in 63 patients (mean age 66.1years, range 35-90) operated with surgical fixation between March 2011 and July 2014 using PERI-LOC locking plate and screws (Smith and Nephew, UK) were identified. Predictors of bone quality were measured from preoperative radiographs, including ratio of the medial cortex to shaft diameter (medial cortical ratio, MCR). Loss of fixation (displacement, screw cut out, or change in neck-shaft angle >4 degrees) was determined on follow-up radiographs.

Results and Conclusion: Loss of fixation occurred in 14 patients (21.9%) during the follow up. Patients were older in the failure group 72.8 vs. 64.2 years (p=0.007). The MCR was significantly lower in patients with failed fixation 0.170 vs 0.202, p=0.019. Loss of fixation is three times more likely in patients with a MCR <0.16 (41% vs. 14%, p=0.015). Increased fracture parts led to increased failure rate (p=0.0005).

Medial cortex ratio is significantly associated with loss of surgical fixation and may prove to be a useful adjunct for clinical decision making in patients with proximal humeral fractures.