Introduction

Elevated remodelling of subchondral bone and marrow tissues has been firmly established as diagnostic and prognostic radiological imaging marker for human osteoarthritis. While these tissues are considered as promising targets for disease-modifying OA drugs, the development of novel treatment approaches is complicated by the lack of knowledge whether similar tissue changes occur in rodent OA models and poor understanding of joint-specific molecular and cellular pathomechanisms in human OA. Here, we describe the establishment of a human OA explant model to address this crucial niche in translational preclinical OA research.

Introduction: Implant loosening/pseudartrhosis after THR/TKR with large femoral bone defects is associated with pain and immobilization in a wheelchair. In these cases a total femur replacement (Combined total hip and knee replacement connected with an intramedullary rod) can be a therapeutic procedure as known from tumor surgery. We describe this technique and results with in a case serie of patients.

Study Type: Monocentric prospective case serie

Patients and Methods: All patients who had a total femur replacement were followed regularly after 3, 6 months, 1, 3 and 5 years. The follow up was documented with clinical examination, x-rays and validated questionnaires. Indications were loosening after stem revisions (THR), pseudarthrosis and loosening of femoral component after TKR, pseudarthrosis and instability after THR and fracture.

For every case the implants were planned with a total leg x-ray and manufactured (Link). The implants were removed and the knee and hip joint prepared. The approach was performed with two incisions (knee, hip) to reduce the invasivity. The implantation started with the knee implants connected with the intramedullary rod and was finished with the hip implants. Postoperative weight bearing was following pain.

Results: Included were 5 cases of total femur replacement in 4 patients (three women, age from 54 to 69) with a follow up between 12 to 94 months, average 3.5 years. Three cases with stem loosening after THR and revisions before, one case with loosening and pseudarthrosis after TKR, one with pseudarthrosis and instability after THR with femur fracture. Every patient had 2–4 interventions of the affected joint before.

The pain diminuished significant in all patients in the questionnaires and the pain medication could be reduced substantially. All patients gained mobility already three months after the procedure, every patient could walk with crutches. No patients needed to be reoperated in the follow-up period. Every patient could keep the mobility over the the follow-up time. Two patients reported some pain in the knee. Radiologically the defects of the femur were partially consolidated and we could not see further bone loss.

Conclusion: Total femur replacement can be used also in selected patients with large bone defects after arthroplasty (THR/TKN) and loosening or pseudarthrosis. The patients profit from the reduction of pain and the gain in mobility.