Excellent outcomes after double-locked plating in very low periprosthetic distal femoral fractures

Very low periprosthetic distal femur fractures (PPDFFs) are rare injuries and often have a relatively high failure rate after single lateral locked plating. The double plating technique yields good outcomes in osteoporotic fractures of the distal femur. To date, there is limited information on double-locked plate fixation of very low PPDFFs. This study aimed to evaluate the outcomes and complications of surgically treated very low PPDFFs using double-locked plate fixation.

Between January 2013 and December 2018, sixty-one consecutive patients with PPDFFs have been conducted. Only Su type III PPDFFs with double-locked plate fixation through a lateral minimally invasive approach and a medial subvastus approach to the distal femur were analyzed. Patients were encouraged to perform straight leg raising exercises and active knee motion on the second postoperative day. Assisted weight bearing from the early postoperative days was supported, and full weight-bearing was allowed after healing the fracture site. All patients were evaluated according to the time to union, limb alignment, range of knee motion, Knee Society Score, and presence of complications.

Twenty one patients (17 females and 4 males, mean age 76 years, range 56-90) were included in the study. There were 10 of 33-A1, 6 of 33-A2 and 5 of 33 A3 fractures, according to the AO classification. Of 21 patients, 20 achieved union at an average of 14 weeks postoperatively. Postoperative limb alignment was satisfactory in all cases, with an average mechanical distal lateral femur angle of 89° and average mechanical posterior distal femur angle of 86°. All patients recovered the knee joint motion similar to that of the contralateral side, and daily life pre-injury. The average knee and function scores were 94 and 89, respectively. There were one case of non-union and three cases of superficial wound infection, which resolved after intravenous antibiotic therapy.

Double locked plating showed excellent radiographic and functional outcomes with few complications in patients with very low PPDFFs. Based on these promising results, we propose the consideration of double-locked plate fixation in the treatment of very low PPDFFs.