The souter-strathclyde elbow prosthesis in rheumatoid patients : an in-depth clinical, radiological and biomechanical analysis

Abstract

The first goal of this thesis was to evaluate the results of primary elbow prostheses used in rheumatoid patients. A systematic review on elbow prostheses is given, with special emphasis on the complication rates (Chapter 2). The second goal was to evaluate the long-term results of 204 primary Souter-Strathclyde total elbow prostheses in rheumatoid arthritis patients at the Leiden University Medical Center (Chapter 3). Highlights on the surgical technique are presented (Chapter 4). The third goal was to assess the reasons for failure of the Souter-Strathclyde total elbow prosthesis. Potential failure mechanisms might be related to previous surgery, prosthetic size and position and bone stock. In Chapter 5 to 8 these aspects are presented. Three failure mechanisms are evalated more closely: 1. Previous surgery Some rheumatoid patients with synovitis of the elbow joint first undergo a synovectomy before replacement therapy is chosen. It was hypothesized that previous open synovectomy could harm the outcome of primary elbow prostheses because of scare tissue with increased chance on infection and limited range of motion. 2.Prosthetic position The prosthetic alignment was determined by measuring conventional radiographs during the follow-up in a standardized manner. Since radiolucent lines (RLLs) are the radiological indication in the loosening process, the elbow components position in the bone was related to the development and progression of these RLLs. It was hypothesized that prosthetic position did influence the loosening process. Radiostereometric analysis (RSA) is used for accurate migration measurements during the follow-up of prostheses (K_rrholm 1994, Ryd 1995, Valstar 2002). Aseptic loosening starts with early onset prosthesis migration. Evaluation of migration patterns with RSA during long term follow-up might elucidate this process. 3.Biomechanical prosthesis-bone interface failure The size of the component, related to the bone size, on torsional stiffness and torque to failure was tested in a cadaveric study design. The hypothesis that larger components give more torque strength was investigated. Finally, the last goal was to evaluate the outcome of revision surgery after failure of a primary Souter-Strathclyde total elbow prosthesis (Chapter 9).