Proximal Femur Locking Plate for Sub-Trochanteric Femur Fractures: Factors Associated with Failure

INTRODUCTION: Proximal femur locking compression plates (PF-LCP) have gained popularity since their inception due to superior biomechanical stability and durability but clinical experience has shown conflicting results including implant failure. OBJECTIVE: To study the incidence of implant failure in patients with sub-trochanteric fractures managed with proximal femoral locking compression plate and identify potential risk factors associated with the failure. MATERIALS & METHODS: Fifty patients with sub-trochanteric fractures, operated upon with titanium PF-LCP were included in the study from January 2012 to December 2014. These plates were of two designs including one five 5.0 mm proximal locking screws (implant A) and other with three 6.5 mm proximal locking screws (implant B). Fractures were classified according to AO/OTA and Seinsheimer classification. Patients had regular follow-up visits for at least a year, allowing for clinical and radiological assessment of union and implant-related complications. RESULTS: A total of 13 out of 50 (26%) plates failed of which 7 were implant fractures, 3 screw breakage and 3 screw cut outs. 70% of the failures occurred in elderly females. Overall implant failure was significantly more common in patients >50 years (p 0.04). Comparing the two different designs of implants used, implant A was more likely to fail at a plate screw density of 0.8 or more (p 0.02), whereas implant B was associated with significant failure when less than 4 proximal screws were used (p 0.03). CONCLUSION: This study revealed a high failure rate (26%) of this implant. Attention to the neck shaft angle difference, number of proximal screws and plate screw density may help reduce failure rates, particularly in elderly osteoporotic females.