Osteosarcoma is the most common type of primary bone cancer, which usually appears in the distal femur. The diagnosis of this condition typically involves advanced imaging and tissue biopsy, as well as taking into account characteristic clinical and radiographic indicators. The treatment approach for distal femoral osteosarcoma is multidisciplinary and involves initial chemotherapy, followed by limb-sparing surgery, reconstruction of bone and soft tissue, and subsequent adjuvant chemotherapy. We present a case study of a 25-year-old male admitted with a blastic lesion in the distal femur, confirmed via open biopsy to be osteoblastic osteosarcoma. Further evaluation revealed multiple pulmonary nodular lesions, managed with chemotherapy. After four months, regression of the lesion was observed. Due to malignant clinical and imaging features, excision of the lesion and subsequent reconstruction were performed, utilizing a custom-made total knee arthroplasty. The excision encompassed the removal of the distal 14 cm of the femur, with histological examination confirming central osteoblastic osteosarcoma. Satisfactory outcomes were observed during a one-year follow-up, indicating promising results. Vigilance is crucial, especially in young patients with surface-type bone tumors, as this neoplasm requires consideration.

Patients with amyotrophic lateral sclerosis (ALS) who undergo lower extremity joint arthroplasty are rarely encountered. Patients with ALS are at an increased risk for perioperative anesthetic complications. Anesthetic techniques, regional or general, present different risks to patients with ALS. The historical concern of worsening pre-existing neurologic symptoms with regional anesthesia is being re-examined in light of emerging evidence supporting its use in patients with ALS. Here, we present the successful perioperative management of a patient with severe bulbar ALS undergoing total knee arthroplasty. Despite his advanced bulbar symptoms, he was independently ambulatory with severe knee pain related to osteoarthritis. During multidisciplinary planning with the patient and his wife, it became clear that his primary perioperative concern was avoiding intubation, prolonged ventilation, and tracheostomy placement. With this in mind, we planned for a neuraxial anesthetic without intraoperative sedation, a postoperative adductor canal peripheral nerve block, and multimodal non-opioid analgesia. There were no perioperative complications. At the six-week follow-up, he experienced improved ambulation and showed no signs of worsened ALS symptoms.

The incidence of unilateral minor heterotopic ossification after primary total knee arthroplasty is still unknown, but bilateral severe heterotopic ossification is rare and has not been reported before. Presented in this report is a 60-year-old female patient who developed bilateral knee pain and stiffness 2 weeks after primary total knee arthroplasty. Her weight was 70 kg and body mass index was 32.2. Preoperatively, she had bilateral varus deformity of both knees. X-rays taken 3 months after surgery revealed bilateral severe heterotopic ossification. The patient had been on non-operative treatment (including anti-inflammatory drugs and physiotherapy). There was a marked improvement 6 months after surgery. This case report showed the non-operative treatment may produce acceptable results for patients with severe bilateral heterotopic ossification after primary total knee arthroplasty, and exerted no influence on the final clinical outcome.

Arthroplasty implants are comprised of metal alloys designed to function within the human body. Implant-related issues and associated soft-tissue reactions have been well documented for modular revision hip and knee constructs. This case highlights findings of metallosis in the context of polyethylene wear in a failed primary total knee arthroplasty. Fretting of a polyethylene reinforcement pin within the tibial baseplate as a direct result of knee joint instability appears to be the root cause of observed periprosthetic metallosis. Enhanced design principles and improved polyethylene locking mechanisms may be useful to potentially mitigate fretting-related issues in future knee replacement designs. The authors recommend surveillance in patients with this construct especially when prosthetic instability is present.

BACKGROUND: Early failure in cemented total knee replacement (TKR) due to aseptic loosening is uncommon. A small number of early failures requiring revision were observed at one hospital due to observed cement-implant fixation failure. The purpose of this case series is to report and identify possible causes for these early failures.
METHODS: Between May 2005 and December 2010, 3048 primary TKRs were performed over a five-year period of time by six surgeons. Two total knee systems were used during this period of time. Nine early failures were observed in eight patients. High viscosity cement (HVC) was used in all these cases.
RESULTS: Aseptic loosening of the tibial component was observed in all nine early total knee failures. The high viscosity bone cement was noted to be non-adherent to the tibial trays at the time of revision surgery. HVC was used in all these cases.
CONCLUSIONS: Properties of HVC may contribute to make it more susceptible to early failure in a small number of TKRs. HVC in total hip replacement (THR) has been associated with cement micro-fractures, cement debris generation and early implant failure. The mechanical properties of HVC may similarly contribute to early failure at the cement-implant interface in a small percentage TKRs.