Abstract
Purpose of study:
Up to 30% of distal femur fractures treated with a locked plate have problems with union. Distal femur locked plates have become a very popular means of internal fixation because of their ability to provide stable distal peri-articular fixation. In spite of this enthusiasm however several studies have reported significant problems with healing. In the distal femur it is recognized that locked plate fixation may be too rigid if used in certain configurations preventing the essential micro movement required for biological healing. Implant failure may arise from rigid configurations that cause excessive hardware stress concentrations. In an attempt to address these problems longer plates and an increased working length have been proposed to reduce construct rigidity. The purpose of our study is to investigate whether an increased working length translates into improved healing.
Description of method:
We undertook a retrospective review of 92 consecutive cases performed at our institution from 2007–2010. Case notes and X-rays were reviewed. Working length, plate to fracture zone ratios and working length to fracture zone ratios were calculated. Union was assessed radiographically and clinically. Covariates of smoking, age, sex and fracture severity were included. Outcomes considered were union or established non-union. Delayed union was defined as union after 20 weeks.
Summary of results:
Median time to union was 16.9 weeks. 11 delayed unions (23.4%, 95%CI(10.8–36.0%)), 3 non-unions (6.4% 95%CI(0.0–13.6%)) and no implant failures were recorded. Our data are consistent with the previously reported proportion of distal femur fractures treated with a locked plate that have problems with union. Although trends were present, no significant associations between impaired healing and exposure variables were found.
Conclusion:
While biomechanical studies have demonstrated increased flexibility of longer plates with an increased working length, clinically this did not translate into significantly improved fracture healing in our study.
