Ipsilateral stress fracture of the proximal fibula after total knee arthroplasty in a patient with severe valgus knee deformity on a background of Rheumatoid arthritis.

INTRODUCTION: Previous studies have reported a lower extremity stress fracture after total knee arthroplasty (TKA). However, a fibular fracture after TKA is quite rare. We report a case of proximal fibula fracture after TKA in a patient with rheumatoid arthritis (RA). PRESENTATION OF CASE: A 45 year old woman with RA had severe knee and foot pain with an antalgic gait disturbance. There was a significant joint deformity in many of lower limb joints. Interval bilateral TKAs were performed two weeks apart. Right TKA was performed using a constraint-type prosthesis, through lateral parapatellar approach. Left TKA was performed using a posterior-stabilized (PS) prosthesis through the more commonly employed, medial parapatellar approach. Seven weeks after the right TKA, the patient was found to have an atraumatic proximal fibular fracture. The fracture went on to heal conservatively. DISCUSSION: The fracture was considered to have occurred after the TKA. The callus appeared eleven weeks after the TKA. The factors that contributed to the fracture were thought to be overload of the fragile bone secondarily to disuse osteopaenia, RA or potentially the significant valgus malalignment correction. The surgical approach, the implant or implantation or the persisting joint deformity, were thought to be contributing factors to the aetiology of the stress fracture. The resultant change in clinical outcome/course is outlined in this case report. CONCLUSION: A stress fracture of the proximal fibula has the potential in the aetiology of may cause other stress fractures, joint other instability, and/or malalignment of the total lower extremity.

Charcot Fracture in the Calcaneus after Total Knee Arthroplasty: A Case Report.

INTRODUCTION: Only a few reports have described calcaneus fractures after total knee arthroplasty (TKA). Therefore, in this report, we describe a case of calcaneal avulsion fracture that occurred 5 weeks after a TKA in a relatively young male patient with syphilis. CASE REPORT: A 63-year-old man with syphilis had Charcot joint of the right knee. The patient developed severe varus deformity and contracture and experienced severe pain in the knee. TKA was performed to alleviate the pain and improve the patient's gait. The patient noticed slight heel pain 4 weeks after the TKA, and a calcaneus avulsion fracture in the ipsilateral foot was diagnosed without any trauma 1 week later. Open reduction internal fixation was performed with cannulated cancellous screws and a cerclage wire. 3 weeks after the surgery, partial weight bearing was permitted in an orthotic device. Full weight-bearing was allowed at 7 weeks after surgery. The surgical wounds healed without complications. The calcaneus fracture successfully achieved bone union with appropriate surgical intervention and aftercare. CONCLUSION: The previous studies have shown that calcaneus stress fracture may occur in elderly osteoporotic women after TKA. Patients with peripheral neuropathy may develop a Charcot fracture after minimal trauma because of decreased protective sensation, even if the patient is a relatively young man without osteoporosis. Charcot joint disease is also considered to be a risk factor for calcaneal stress fracture and Charcot fracture after TKA.

Load-transfer analysis after insertion of cementless anatomical femoral stem using pre- and post-operative CT images based patient-specific finite element analysis.

Periprosthetic bone remodeling is commonly seen after total hip arthroplasty, but the remodeling pattern differs among patients even in those implanted with the same stem. Remodeling occurs mainly because of the difference in load transmitted from the stem to the femur. In this study, we evaluated the load-transfer pattern in eight female patients implanted with an anatomical stem on an individual basis by patient-specific finite element analysis that is based on pre- and postoperative computed tomography images. Load transfer was evaluated using interface stress between the stem and bone. One of eight patients demonstrated proximal dominant load transfer, while the other patients demonstrated a distal dominant pattern. The results of our biomechanical simulations reveal the differences in load-transfer pattern after surgery among patients with the same anatomical stem.

Bilateral Calcaneal Avulsion Fracture Complicated with a Delayed Achilles Tendon Rupture in a Patient with Diabetes: A Case Report.

CASE: A sixty-five-year-old man with diabetes mellitus had bilateral calcaneal avulsion fracture without a history of trauma. Both fractures were treated surgically with modified tension-band wiring, cerclage wiring, and screws. Six months after the surgery on the left side, the patient had a left Achilles tendon rupture proximal to its insertion into the calcaneus. CONCLUSION: Calcaneal avulsion fractures are rare but often have complications. Even if these fractures are managed by well-established treatment methods, an unanticipated complication, namely a delayed Achilles tendon rupture, can occur in patients with diabetes.