Methodology and information-measuring system for personalized synthesis of lower limb prostheses

Introduction: One of the methods for managing the quality of prosthetics is optimizing the composition of a modular prosthesis components. Mistakes in choosing models for functional modules of a prosthesis lead to a limited realization of the patient's potential capabilities, or to the choice of expensive highly functional models whose potential cannot be fully realized with the given body system disabilities. One of the most effective ways to solve this problem is to use the computer technology capabilities. Purpose: Substantiation of the methodology for the development of an innovative computer technology for personalized synthesis of a lower-limb prosthesis, including the development of the structure of an information-measuring system for its implementation. Methods: Analysis, synthesis, analogy; expert survey; analytic hierarchy process (Saaty method). The conceptual language of the International Classification of Functioning, Disability and Health was used to describe the factors influencing the requirements for the characteristics of prosthetic modules. Results: In order to choose models for prosthetic modules, we should use an extended system of factors, including both the basic factors associated with the purpose of the products and indicated in the catalogs, and additional factors: impairment indicators of the body functions and structures, the capacity and performance of the patient's activity and participation, the presence of barriers and facilitators environmental factors in which the prosthesis is planned to be used. Taking this system of factors into account, a structural diagram of an information-measuring system for examining a prosthetic patient has been developed. To select the components for the prosthesis, we have substantiated the necessity of creating a global electronic catalog, combining structured information on the models of prosthetic modules supplied by various manufacturers. A matrix representation form is proposed for the knowledge base, reflecting the rules for choosing models according to the correspondence of their characteristics to the estimates of the factors. The methodology of computerized selection of models from the electronic catalog has been substantiated. Practical relevance: The results of the work are a step towards the creation of a technology for a computerized multicriteria choice of components for a modular prosthesis, taking into account the personal needs and functional capabilities of the patient. The use of this technology will improve the patient's rehabilitation level and the quality of his or her life.

Higher incidence of aseptic loosening caused by a lower canal filling ratio with a modified modular stem in total hip arthroplasty

Purpose Although a cementless modular prosthesis has shown reliable results, cases of unstable fixation and revision due to aseptic loosening were observed in our institute. The purpose of this study was to clarify the causes of unstable fixation of the prosthesis. Methods A total of 144 patients (154 hips) who underwent total hip arthroplasty using the modular prosthesis were retrospectively investigated. For the cohort study, 97 patients (104 hips) were included. The femoral component survival rate and sleeve fixation were assessed at a minimum follow-up of 5 years. Patients were divided into 2 groups, including stable and unstable fixation groups, by sleeve fixation. Clinical and radiographic outcomes were compared. Results The Kaplan-Meier survival rate at 9 years was 93% with revision for any reason as the endpoint in study cohort. The reasons for revision were recurrent dislocation (1 hip) and aseptic loosening of the stem (5 hips). A total of 88 hips (84.6%) showed stable fixation, and 16 hips (15.4%) showed unstable fixation at final follow-up. There was no significant difference in clinical outcomes between the 2 groups at final follow-up. The canal flare index was significantly higher, and the canal filling ratio was significantly lower in the unstable fixation group. Conclusion Although the modified modular prosthesis was useful for treating anatomically difficult patients, we need to pay attention to both proximal/distal mismatch of the intramedullary canal and the canal filling ratio to achieve stable fixation and good long-term results.

Analysis of Difficulties and Complications Following Implantation of Modular Prostheses in Patients with Lower Limb Bone Tumours

Background. The implantation of a modular prosthesis is the most popular method of reconstruction of bone defects in oncological patients. Along with clear-cut benefits associated with this procedure, there is also an increased risk of complications. Common complications include deep infections, aseptic loosening and mechanical implant damage. This study assessed the risk of complications following the implantation of a resection prosthesis in patients with lower limb bone tumours and to evaluate difficulties encountered during the treatment. Material and methods. A total of 149 patients with lower limb tumours treated at the Department of Oncological Ortho­paedics in Brzozów had resection prostheses implanted in the years 2016 and 2017. We analysed this series and available literature reports with regard to complications of the procedure and those encountered during the treatment. Results. The mean duration of the surgical procedure was 117±45 minutes. Intraoperative complications occurred in 18 cases. Gluteal muscle failure was seen in 34 (43%) of the 74 patients with proximal femoral tumours, and impaired knee extension was noted in 4 (67%) of the 6 patients following resection of the proximal tibia. There were two cases of dislocation following megaprosthetic reconstruction of the hip joint. Impaired wound healing was noted in 7 (5%) patients. Post-operative trophic lesions of the skin were seen in 2 (2%), and peripheral nerve damage in 2 (2%) patients (fibular nerve). Thromboembolic complications were noted in 3 (3%) patients. No aseptic complications, mechanical implant damage or deaths were recorded. Conclusions. 1. The most frequently encountered complication following the implantation of a modular prosthesis was muscle failure, which was associated with the extent of the procedure. 2. Aseptic loosening and mechanical implant damage were rare and occurred in the early postoperative period.