Unicortical screws or insufficient graft compression can result in nonunion and breakage of screws [5, 33].
Insufficient fixation of the screws may cause partial loss of reduction with secondary displacement of the humeral head into varus position leading to unsatisfactory result.
Traditional treatment of osteoporotic proximal humerus fractures with conventional plates and screws leads to high failure rates due to the bone resorption underneath the plate, high rotational forces, and insufficient purchase of the screws in the frequently osteoporotic humeral head [ 12].
Axis correction was considered sufficient in both groups (Table 2, Figures 5 and 6); however, 4 patients in the nail group and 6 patients in the fixator group had minor residual deformities, whereas 1 patient in the nail group developed a procurvatum deformity during lengthening due to insufficient placement of blocking screws.
These possible causes include patient factors (non-compliance, smoking and poor personal hygiene), biological factors (fracture fragmentation, impaired circulation, bruised muscular envelope and secondary infection) and mechanical factors (no bone graft, unfilled screw holes and insufficient immobilisation).
When performing osteosynthesis for osteoporotic fracture, however, excessive sliding of the lag screw caused by insufficient abutment at the fracture may shorten the femur.
In small glenoids, the standard glenoid implant (29-mm) is larger than glenoid bone stock, which results in insufficient bone-implant contact and screw fixation, especially of anterior and posterior holes of the baseplate.
However, in cases of poor bone quality or high mechanical demand before consolidation, this fixation may be insufficient, leading to loosening of screws, and consequently, delay or nonunion of the fracture or inadequate bone alignment.
Three intraoperative complications occurred in 3 patients (1.1%): 1 perforation of the endo button into the femur, 1 second screw tunnel because of insufficient anterior coverage, and 1 Kirschner wire breakage.
According to these known risk factors for fixation failure described by the authors, we found an obvious insufficient length of the retrograde placed screws.
