Novel Implant, Novel Pattern of Failure: Potentially Occult but Implant Specific Failure of a Variable Locking Distal Femoral Plate

The incidence of distal femur fractures is increasing, especially among osteoporotic patients and those associated with joint prostheses [1]. Laterally positioned plates with locking screw options are frequently utilized devices for the stabilization of these injuries in isolation or in combination with medial plates and/or intramedullary nails. The Depuy Synthes 4.5 mm Variable Angle Locking Compression Plate (VA-LCP) Curved condylar Distal Femur Plate system (West Chester, PA, USA) was introduced to the US market in 2011 following FDA 510(k) clearance [2]. It aimed to provide more versatile screw locking options compared to the existing fixed angle locking screw solutions with the addition of variable angle locking screw positioning options [3]. The new design involved the change of the well-established fixed angle LCP combination holes on the plate to accommodate operator freedom in the angle of locking screw position in relation to the plate. The widespread use of the new VA-LCP was associated with reports on potentially higher and earlier rates of mechanical implant failure [4-6]. An 82-year-old female with an AO/OTA type A periprosthetic distal femur fracture was managed with a Depuy-Synthes 14-hole VA-LCP with 2 locking extension plates proximally. As optimal postoperative care weight bearing as tolerated was recommended immediately. Postoperatively, the thigh pain never settled and 10 weeks after the injury, there was radiological evidence of the bent VA-LCP plate (Figures 1 and 2). At revision surgery, the removed plate revealed fractured implant at three consecutive VA tabs to the periphery of the plate without the complete disruption of the plate continuity at any single level (Figure 3). Despite the documented concern about potential early failure of the selected implant, there has been no reported evidence of this unique pattern of failure, which can be occult to clinicians for a while before apparent plate breakage. The distal femur VA-LCP propensity to collapse into varus with the plate fracturing from the VA tab to the periphery of the plate through sequential holes may result in the plate bending rather than obvious breaking. Our main message is not the fact of the failed implant, which can be related to surgical technique, compromised local blood supply, bone quality, and co-morbidities, but rather the specific and potentially insidious pattern of failure. This is likely to occur over time, which can be difficult to appreciate on plain radiographs. A low index of suspicion is required to investigate sub-total mechanical failure with the use of this plate, especially in the context of ongoing pain. Advanced imaging may be required to identify the fracture lines prior to catastrophic failure, which usually requires more invasive surgery in an unplanned fashion in frequently frail patients with several co-morbidities at high-risk for major surgical procedures. Open access publishing facilitated by The University of Newcastle, as part of the Wiley - The University of Newcastle agreement via the Council of Australian University Librarians. Zsolt J. Balogh is the Deputy Editor-in-Chief of the ANZ Journal of Surgery and was not involved in any aspect of the peer-review process of this submission. The authors declare no conflicts of interest.