Total hip arthroplasty is nowadays a common treatment for a large number of pathological cases regarding the hip joint and is considered as the most successful orthopedic operation. With the mean age of patients constantly decreasing and the more intense way of life, the need for versatile implant designs has arisen. Currently modular hip implant systems are used extensively in order to compensate for difficult occasions, where offset and version correction are required. In addition to this femoral heads of bigger diameter have been introduced to deal with issues such as dislocation and impingement, although their influence on the mechanical behavior on the bone – implant assembly is not widely documented. Towards this direction a finite element model was generated. Computed tomographies of a cadaveric femur were used as raw data and processed, a Profemur-E system with variable heads was digitized, thus leading to a complete assembly consisting of the femur, the stem, the necks and the femoral heads in the commercial CAD software Solidworks. For typical loading scenarios – the stance phase of the gait cycle – the finite element analysis was performed in ANSYS Workbench. The results showed that the implementation of BFH and the neck version produced an increase in strains and stresses with respect to a normal head of 28mm and a straight neck in areas of clinical interest such as the calcar, the greater trochanter area and the stem tip region, considered responsible for thigh pain.
Total Hip Arthroplasty (THA) is one of the most important procedures in the fields of Reconstructive Orthopaedics. This study aims to present the preliminary results of the clinical and radiological evaluation of patients who have undergone THA with metal bearings, modular necks and big femoral heads and to correlate them with the results of the Finite Element Analysis. In the period from 1/1/2006 until today 90 patients (33 men and 57 women) with mean age 62,4 years have undergone primary THA. The patients were clinically and radiographically evaluated preoperatively, as well as postoperatively, in regular time intervals (1st, 3rd, 6th, 12th month and every year afterwards). The clinical assessment was based on two scales, Harris Hip Score (HHS) and Merle d’ Aubigne (MDA) score, whereas the radiographic on Engh criteria. The mean follow up was 16 months. The mean preoperative HHS and MDA score were 45 and 10,3 respectively, whereas 89 and 16,74 at the last evaluation. The mean Engh score was 16,12. No incidence of dislocation, infection and cup or stem adverse effect occurred. We demonstrate extensively, with respect to the used combination of neck and femoral head, the radiographic findings in the zones of Grün and Charnley, in the areas of the tip of the stem and the calcar, as well as the resulting clinical manifestations. The early clinical and radiological data are in line with the increase in the stresses and strains on the upper part of the femur, which are revealed through the Finite Element Analysis.
The aim of this study is to evaluate the mid-term results of the Genesis Total Knee Prosthesis, one of the first prostheses with asymmetric shape of the tibial component .The arthroplasty was performed on our patients with retention of the posterior cruciate ligament and, in most of the cases, without replacement of the patella. During the period 1992–1999, 90 patients (116 knees) were operated in our clinic: 81 of them were women and 9 were men with an average age of 68 (52–82) years. The primary indication for the operation was osteoarthritis. 84 patients (109 knees) were evaluated clinically and roentgenographically (Knee Society Knee Score) for a mean time of 98.1 (29.6 – 137.7) months after surgery. There were no infections. (Three) Four of the patients had to undergo a second operation . Two of them, eventually, had their patellae replaced (1,5 and 3 years postoperatively) due to persisting pain of the patellofemoral articulation and lateral patellar subluxation .The other two patients had to undergo revision arthroplasty due to wear of the polyethylene component, one at five years and the other at nine years . Moreover, wear of the polyethylene was also observed on another patient, radiographically, six years after the operation. However, the patient seemed to have no symptoms and was, therefore, unwilling to undergo a revision. The clinical results were satisfactory with a Knee Score of 97(74–100) and Function Score 80 (5–100) .The mean range of motion was 113°(85°–135°). There was no evidence of loosening or any radiolucent lines found radiographically .We consider the results of the Genesis Total Knee Arthroplasty satisfactory .The asymmetric shape of the tibial condyles ensures the fitting of the tibial component. With the exception of cases of severe patella damage, replacement of the patella is not required. The presence of any problems in the patellofemoral articulation is usually connected to the maltracking of the patella or to errors in the surgical technique.
