Influence of the taper on the fretting wear of the femoral stem-femoral head taper junction in total hip prosthesis

Purpose The purpose of this paper is to study the roughness effect on the fixation of taper junction components and surfaces wear in terms of taper surface design. The roughness of the femoral heads’ taper and of the femoral stems’ trunnions can influence the fretting wear of the taper junction. Design/methodology/approach It was analysed whether a microgrooved taper surface of the femoral stem trunnion improves the fixation and reduces the wear rate at the taper junction of the hip prosthesis. Two models have studied: a femoral head with a smooth tapered surface combined with a microgrooved stem trunnion and a femoral head with a smooth tapered surface combined with a trunnion that had a smooth surface of the tapered. To compare the wear evolution between these two models, a computerised finite element model of the wear was used. Findings The results obtained after analysis carried out during millions of loading cycles showed that the depth of the linear wear and the total material loss were higher for the femoral heads joined with microgrooved trunnions. The main conclusion of this paper is that the smooth surfaces of the taper and of the trunnions will ensure a better fixation at the taper junction, and therefore, will reduce the volumetric wear rates. Originality/value A higher fixation of the taper junction will reduce the total hip prosthesis failure and, finally, it will improve the quality and durability of modular hip prostheses.

P039 Evolutionary course of Juvenile Idiopathic Arthritis

Background Juvenile idiopathic arthritis (JIA) is a heterogeneous group of rare conditions that begin before the age of 16. Seven categories have been defined by the International League of Associations for Rheumatology (ILAR) classification. The aim of our work is to describe the demographic, clinical, and radiological characteristics and therapeutic of patients with JIA. Materials and methods A retrospective, descriptive study of patients followed for AIJ in the rheumatology department of Mohamed LamineDebaghine during a period of 15 years (2005–2020). Patients were included if satisfied ILAR criteria. Results Ten patients with JIA were included, 5 of whom were females. The mean age of onset was 9.20 ± 3.15 (range: 5–14 years). The subtypes were as follows: 4 patients had RF-negative polyarthritis, one case had RF-positive polyarthritis, one with systemic arthritis form, 2 cases of oligoarthritis, 1 case of psoriatic arthritis, and enthesitis-related arthritis. Three children have coxitis. ACPA was positive in one case and antinuclear antibodies were negative. Eight patients have developed osteoarticular destruction. Pulmonary involvement was noted in a patient who had RF-positive polyarthritis. Corticosteroid therapy was prescribed in 9 patients, 5 of whom developed complications related to steroids, including growth retardation, which was observed in 3 cases. Nine JIA patients received methotrexate. The use of etanercept and IL-1 inhibitors were required in 7 and 1 cases, respectively. Corticosteroid infiltrations were performed in 9 patients. Total hip replacement was indicated in 3 patients. Conclusion Through our study, we note a predominance of the polyarticular form. Osteoarticular destruction seems to be frequent, particularly in the hip. The use of biotherapy and the total hip prosthesis proved the severity of juvenile idiopathic arthritis in our patients.

Periprosthetic Infection on a Revised Total Hip Prosthesis Treated with Deep Lavage and Vacuum Dressings: A Case Report with 4-Year Follow-Up

Periprosthetic hip infections are a dreaded complication met among most orthopedic surgeons after arthroplasty procedures especially in susceptible patients. We report a case of a patient with periprosthetic infection after a revised total hip arthroplasty. She was treated with deep lavage and debridement, combined with IV anti-biotherapy and vacuum dressings. A 4-year follow-up shows an infection-free patient with an acceptable functional status and quality of life. Suppression of the infection, with salvage of the prosthesis and maintaining an acceptable functional status, is a satisfactory result that can be achieved in selected cases.

Finite Element analysis of stress state in the cement of total hip prosthesis with elastomeric stress barrier

In the total hip prosthesis, according to different positions of the patient, there are a variety of loads acting on femoral head which generate stress concentration in the cement called polymethylmethacrylat (PMMA) and consequently in the interfaces stem/cement/bone. This load transfer can provoke loosening of the implant from the femoral bone. This paper focused on optimal stress distribution in the total hip prosthesis and devoted to the development of a redesigned prosthesis type in order to minimize stress concentration in the cement. This study investigated the effect of elastomeric stress barrier incorporated between the stem and femoral head using 3D-finite element analysis. This proposed implant provoked lower load transfer in the cement due to the elastomeric effect as stress absorber. However, the proposed model provided an acceptable solution for load transfer reduction to the cement. This investigation permitted to increase the service life of the total hip prosthesis avoiding the loosening.

Zurich Cementless Dual Mobility Cup for Canine Total Hip Prosthesis: Implant Characteristics and Surgical Outcome in 105 Cases

Dislocation after total hip arthroplasty (THA) remains a troublesome complication, and a source of frustration for the owner and the surgeon. The dislocation rate of hip prostheses in dogs is reported to range from 4 to 15%, representing the most common short-term complication. This is especially true in large and giant breed dogs, usually requiring revision surgery. With the increase in the number of THA being performed in veterinary surgery, reducing or preventing complications such as postoperative THA dislocation will be of paramount importance. The Zurich cementless dual mobility (DM) system allows impingement-free range of angulation of 80 to 132 degrees between the ceramic head and the polyether ether ketone (PEEK) cup when combined with the range of the PEEK cup in the outer metal cup. In this article, we review the use of the DM cup in THA in large and giant breed dogs, in terms of its history, biomechanics, outcomes and complications based on 105 cases.

A Particle Swarm Optimization-Based Approach for Finding Reliability in a Total Hip Prosthesis

Nowadays, we assist the global extension of reliability optimization problems from the design phase of systems and sub-systems to the design and operational phases, not only of systems and sub-systems, but also of bio functionality design. This chapter investigates the relative performances of particle swarm optimization (PSO) variants when used to find reliability in the total hip prosthesis by finding the maximization of jumping distance (JD) to avoid dislocation and the minimization of system's stability to offer mobility. Statistical analysis of different cases of head diameters of 22, 28, 36, 40 mm has been conducted to survey the convergence and relative performances of the main PSO variants when applied to solve reliability in the total hip prosthesis.