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Precontoured distal femur locking plates yielded poor fit before, after TKA
Published results showed under-contouring of precontoured distal femur locking plates led to plate-bone mismatch, with a worse fit after total knee arthroplasty.
Sean T. Campbell, MD, and colleagues determined plate-bone distance in 53 patients who underwent TKA. Researchers digitally templated four standard-length, precontoured distal femur locking plates (Synthes 4.5 LCP, DePuy Synthes; Smith & Nephew 4.5 Peri-Loc, Smith & Nephew, Stryker 5.0 AxSOS, Stryker; and Zimmer NCB, Zimmer Biomet) onto each patient’s preoperative and postoperative radiographs and compared mean plate-bone distance between the manufacturers and radiographs before and after TKA.
All implants tested had under-contouring in all patients, according to results. Researchers found the precontoured distal femur locking plates had a worse fit after TKA, with plate-bone distances ranging from approximately 6.6 mm to 8 mm preoperatively and from approximately 8.2 mm to 8.6 mm postoperatively. Results showed the Synthes implant had the lowest plate-bone distances prior to TKA, while the Smith & Nephew implant had the lowest plate-bone distances after TKA. Researchers found women had a greater plate-bone increase at 16% vs. 8% among men.
“In this study, we found that four different distal femoral locking plates were under-contoured in all of the patients studied, meaning there was a gap between the plate and the distal femoral metaphysis,” Campbell told Healio.com/Orthopedics. “This is relevant in the setting of fracture fixation when there is a plan to use the plate as a reduction aid. If the proximal segment is brought into contact with the plate in the under-contoured region, this can result in a malreduction. Surgeons treating distal femur fractures with these implants should be aware of this and avoid indiscriminate use of the plate as a reduction template.” – by Casey Tingle
Disclosures: Campbell reports no relevant financial disclosures. Please see the full study for the other authors’ relevant financial disclosures.