Nonunion of Hoffa Fracture Successfully Treated by Total Knee Arthroplasty: A Case Report.

A Hoffa fracture is a rare type of femoral fracture that is difficult to treat. Nonoperative treatments usually result in failure; hence, in most cases, surgical treatments are essential. Nonunion following Hoffa fracture appears to be relatively uncommon, and there are limited reports in the literature about this type of nonunion. These reports suggest that open reduction and rigid internal fixation is the standard treatment for this type of nonunion. This study reports the case of a 61-year-old male patient who suffered from left lateral Hoffa fracture after falling from a truck bed. At the former hospital, open reduction and internal fixation were performed with plates and screws at 8 days post-injury. Postoperatively, displacement of the lateral proximal fragment was observed, and the patient reported left knee pain. Therefore, a revision open reduction and internal fixation was performed 4 months post-surgery. However, 6 months after the revision surgery, the patient reported instability and pain in the left knee, and subsequent radiography revealed nonunion of the fracture in the lateral condyle. The patient was referred to our hospital for further treatment. Treatment by re-revision open reduction and internal fixation was deemed challenging, and so rotating hinge knee (RHK) arthroplasty was performed as a salvage treatment. At 3 years post-surgery, no significant problems were observed, and the patient could walk without any assistance. The range of motion of the left knee was 0 to 100° without extension lag, and there was no lateral instability. Standard treatment for Hoffa fracture nonunion is commonly anatomical reduction and rigid internal fixation. However, total knee arthroplasty may be a better option for the treatment of Hoffa fracture nonunion in older patients.