Does posterior configuration have similar strength as parallel configuration for treating comminuted distal humerus fractures? A cadaveric biomechanical study

BACKGROUND

The posterior plating technique could be used as a clinical alternative to parallel plating for treating comminuted distal humerus fractures (DHFs) successfully with good clinical results. However, the biomechanical characteristics for posterior fixation are still unclear. The purpose of this study is to evaluate the biomechanical properties of the posterior fixation and to make comparisons between the parallel and the posterior fixation systems.

MATERIALS AND METHODS

We performed a cadaveric biomechanical testing with two posterior plating systems (a posterior two plating and a single posterior pre-contoured Y plating system) and one parallel two plating system to treat AO/OTA type-C2.3 DHFs. Among three groups, we compared construct stiffness, failure strength, and intercondylar width changes after 5000-cycle fatigue loading and failure loads and failure modes after destructive tests in both the axial compression and (sagittal) posterior bending directions. The correlations between construct failure loads and bone marrow density (BMD) were also compared.

RESULTS

In axial direction, there were no significant differences in the stiffness and failure load between the posterior and the parallel constructs. However, in sagittal direction, the two-plate groups (posterior two plating and parallel plating group) had significant higher stiffness and failure loads than the one-plate group (single posterior Y plating). There was no fixation failure after 5000-cyclic loading in both directions for all groups. Positive correlation was noted between BMD and failure loads on parallel fixation.

CONCLUSIONS

We found that when using two plates for treating comminuted DHFs, there were no significant differences in terms of most biomechanical measurements between posterior and parallel fixation. However, the single pre-contoured posterior Y plate construct was biomechanically weaker in the sagittal plane than the parallel and the posterior two-plate constructs, although there was no fixation failure after the fatigue test for all groups regardless of the fixation methods.

LEVEL OF EVIDENCE

Biomechanical study.

Open reduction and internal fixation of humeral midshaft fractures: anterior versus posterior plate fixation

Background

Fractures of the humeral shaft represent 2–4% of all fractures. Fractures of the humerus have traditionally been approached posteriorly for open reduction and internal fixation. Reports of treating midshaft fractures with an open anterolateral approach and anterior plating are limited. The purpose of this study was to evaluate a series of humeral shaft fractures treated with plate osteosynthesis regarding the effect of the approach and plate location on the healing rate and occurrence of complications.

Methods

We conducted a retrospective chart review of patients aged over 18 years with humeral midshaft fractures treated with anterior or posterior plate fixation. Selection of the approach to the humerus was based on the particular pattern of injury and soft tissue involvement. The minimum follow-up duration was set at six months. The outcomes included the rate of union, primary nerve palsy recovery, secondary nerve damage, infection and revision surgery.

Results

Between 2006 and 2014, 58 patients (mean age, 59.9; range, 19–97 years) with humeral midshaft fractures were treated with anterior (n = 33) or posterior (n = 25) plate fixation. After a mean follow-up duration of 34 months, 57 of 58 fractures achieved union after index procedure. Twelve fractures were associated with primary radial nerve palsy. Ten of the twelve patients with primary radial palsy recovered completely within six months after the index surgery. In total, one patient developed secondary palsy after anterior plating, and three patients developed secondary palsy after posterior plating. No significant difference in the healing rate (p = 0.4), primary nerve palsy recovery rate (p = 0.6) or prevalence of secondary nerve palsy (p = 0.4) was found between the two clinical groups. No cases of infection after plate fixation were documented.

Conclusions

Open reduction and internal fixation using an anterior approach with plate fixation provides a safe alternative to posterior plating in the treatment of humeral shaft fractures. An anterior approach allows supine positioning of the patient and yields union and complication rates comparable to those of a posterior approach with plate fixation for the treatment of humeral shaft fractures.