Introduction. After total hip arthroplasty, dislocation is one of the most frequent serious early complications. This occurs in part due to impingement (catching and leverage of the neck-cup on the inlay/cup border). Impingement may also negatively impact long-term outcomes. Materials and Methods. A preliminary model for an optimised hip endoprosthesis system was developed to offer a mechanical solution to avoid impingement and dislocation. A computer-supported range of motion simulation using parameters of cup anteversion and inclination as well as torsion and CCD shaft angle was then performed to localise areas of anterior and posterior impingement of typical acetabular cups. Results. Through isolation of the two main trajectories of motion, and modifications with corresponding gaps to the inlay/cup areas as well as oppositional banking in the abduction/adduction plane, the combination of a snap-fit acetabular cup with reduced cup profile was the result: the “bidirectional
Aims: The authors report oncological and functional results after 15 acetabular reconstructions, followed tumor resection, with an original technique using homo-lateral proximal femoral autograft and
Because we encountered a high failure rate of the acetabular component of the uncemented, hydroxy-apatite coated, Omnifit
The ABG
Purpose: The surgical approach is an essential element for precise reduction and rigid fixation of fractures of the acetabulum. In cases where the anterior column is mainly involved and total hip arthroplasty (THA) is indicated, classical approaches do not allow double assess to the anterior column necessary for reduction and fixation and to the femoral canal for insertion of the prosthesis. Combining Heuter’s anterior approach and Letournel’s ilio-femoral approach provides access to the anterior column and to the often associated posterior hemi-transverse fracture, while allowing insertion of the
Introduction. Total hip arthroplasty in young patients is still associated with high failure rates, especially at the acetabular side. Purpose of this study was to evaluate the long-term results of the Alloclassic cementless Zweymüller
Purpose: Wear of prosthetic implants, especially the metal-polyethylene head-cup couple, and dissemination of wear particles throughout the organisms the dominant long-term complication of total hip arthroplasty. We determined serum concentrations of chromium, cobalt, nickel, and molybdenum in patients bearing a
Introduction: “Spongiosa metal” this unique implant surface was introduced in 1982 by ESKA implants Germany. Pore size was between 800 and 1500 microns with an overall porosity of 60%. The pore depth of the interconnecting surface structure reached up to 3000 microns. The purpose of this retrospective study is to report the long term results of Spongiosa Metal I cement less
Purpose: A spacer can be used for two-phase replacement of an infected
SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). We constructed finite element (FE) models and analysed equivalent stresses in the femur. In addition, we measured bone mineral density (BMD) in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress and to compare the results of the FE analyses with changes in BMD after THA. Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA or SL-PLUS formed the basis of this study. Eleven patients received SL-PLUS MIA and ten patients received SL-PLUS. Zones were defined according to Gruen's system (zones 1∼7). Computed-tomography (CT) images of the femur were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analysed in zones 1 to 7 and compared to the DEXA data. FE studies revealed that there was no significant difference in equivalent stress between SL-PLUS MIA and SL-PLUS. BMD was maintained after THA in zones 3, 4, and 5, whereas BMD decreased in zones 2, 6, and 7. In zone 1, BMD decreased in SL-PLUS MIA stem group by 14%, while BMD was maintained in SL-PLUS standard stem.
Introduction: Unique spongiosa like surface structure was introduced in 1982 by ESKA implants Germany. It is called “Spongiosa-Metal I surface” The purpose of this retrospective study is to report and compare long term results of Spongiosa Metal I
INTRODUCTION. Cementless Total Hip Replacement surgery is a well established procedure for relative young patients with severe hip disease. Excellent long term clinical results have been published on the performance of the femoral component. With growing clinical experience, our concern focused on excessive wear of the Ultra High Molecular Weight Polyethylene (UHMWPE) ringloc liner of the Mallory Head cementless
Total Hip Arthroplasty (THA) is a well-established, cost-effective treatment for improving function and alleviating pain in patients who have disabling hip disease with excellent long-term results. Based on the excellent results, there is an ongoing trend for THA to be performed in younger and more active patients, having higher physical demands on their new total joints. Polyethylene (PE) wear and its biological consequences are one of the main causes of implant failure in THA. Macrophages phagocytise PE wear particles and this will result in osteolysis and loss of periprosthetic bone. The risk of these complications can be estimated in relation to the amount of volumetric wear based on two assumptions: that the number of PE particles dispersed in the peri-prosthetic tissues is controlled by the amount of PE wear; and that the development of osteolysis and the resulting aseptic loosening is triggered by these PE particles. Based on these assumptions, a model was developed to estimate the osteolysis-free life of a THA, depending on the Linear Wear Rate (LWR) and femoral head size of the PE bearing. A review of the literature was conducted to provide an estimate of the radiologic osteolysis threshold based on the volumetric wear of the PE bearing. This review demonstrates that this radiologic osteolysis threshold is approximated 670 mm3 for conventional PE. The osteolysis-free life of the THA was estimated by simply dividing this threshold volume by the annual Volumetric Wear Rate (VWR) of the bearing. The annual VWR is basically controlled by two parameters: (1) annual LWR and (2) head size, and was calculated by using published formulae. For 28 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 116.6 years / LWR: 25 µm/y => 46.6 years / LWR: 50 µm/y => 23.3 years / LWR: 100 µm/y => 11.6 years. For 40 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 57.1 years / LWR: 25 µm/y => 22.9 years / LWR: 50 µm/y => 11.4 years / LWR: 100 µm/y => 5.7 years. The osteolysis-free life determined by this model is in good agreement with the clinical results of PE bearings having a 28 mm head size and demonstrates that extreme low LWRs are mandatory to assure a descent osteolysis-free life for THA (PE bearings) using large heads, such as 40 mm. For such head sizes, small variations of the LWR may have large impacts on the osteolysis-free life of the THA.
Customization makes it possible to fulfill design requirements during MIS-THA procedures, and has helped define the parameters of fit and fill. This study describes the results of using customization techniques to develop a femoral implant for utilization. CT-based design criteria for femoral implants has-been developed and used for primary, cement-less, non-minimally invasive THA surgery. Over 1000 procedures performed with these devices have been associated with displaced femoral fractures, and have been revised for septic loosening. This study has 2 parts:
20 implants were designed and implanted with CT-based criteria that utilized the identical fit and fill standards of the custom implants previously established, but had short (<
115 mm), tapered stems; 20 patients underwent primary, cement-less THR wherein an off-the-shelf femoral implant system was determined to fulfill fit and fill requirements of custom implants. The stem of these implants was shortened (95–115 mm) and tapered. Implants in both groups were inserted using a single incision, posterior-lateral MIS approach. Patients were followed clinically and radiographically for six months. Immediate full weightbearing and use of a single cane were encouraged. The use of CT-based customization techniques is helpful for defining design criteria of femoral implants, but the instrumentation for inserting these implants must be adapted to the specific surgery. Customization also facilitates the design and evaluation of CAOS applications for inserting these MIS implants.
Early reports on revision total hip arthroplasty (RTHA) suggested that outcomes of this procedure are as good as those of primary total hip arthroplasty (THA). However, RTHA is associated with longer surgery time, greater blood loss and increased risk of complications (thromboembolism, nerve injury, periprosthetic fractures, recurrent hip dislocations and infections). Aseptic loosening after RTHA was reported in 36% of patients aged over 55 years within 4 years after revision. Infections were reported in 32% and complications during surgery in 23% of patients respectively. Unsatisfactory results of RTHA stimulate the search for alternative procedures. Girdlestone excision arthroplasty (GA) seems to be a good solution for older patients with high risk of complications related to a poor general condition.
Infection ceased in 9 cases, 1 patient died because of complications related to chronic infection.
Post op cup anatomical and functional orientation is a key point in THP patients regarding instability and wear. Recently literature has been focused on the consequences of the transition from standing to sitting regarding anteversion, frontal and sagittal inclination. Pelvic incidence (PI) is now considered as a key parameter for the analysis of sagittal balance and sacral slope (SS) orientation. It's influence on THP biomechanics has been suggested. Interestingly, the potential impact of this morphological angle on cup implantation during surgery and the side effects on post op functional orientation have not been studied. Our study explores this topic from a series of standing and sitting post-op EOS images 310 patients (mean age 63,8, mean BMI 30,2) have been included prospectively in our current post-operative EOS protocol. All patients were operated with the same implants and technique using anterior approach in lateral decubitus. According to previous literature, 3 groups were defined: low PI less than 45° (57 cases), high PI if more than 60° (63 cases), and standard PI in 190 other cases.Introduction
Material and methods
The aim of this study is to review the relation of polyethylene wear in patients underwent Anatomic Medullary Locking total hip replacement with respect to the types of acetabulum used. 85 cementless primary AML joint replacements were performed in the 10 years period from 1988 to 1998. The average age at operation was 46.6 with a range from 22 to 63. Two different types of acetabulum design namely the Acetabulum Cup System (ACS) and Duraloc were used. 39 of them were followed up from 2 to 10 years with an average of 69 months. Xrays were performed at the review visit and the thickness of the insert was calculated. The cup abduction angle was measured and the size of the cup and initial insert thickness was also recorded. The findings were correlated and subjected to statistical analysis. Our findings suggested that the wear of the ACS cup was significantly higher than that of the Duraloc cup. The size of the cup but not the age of the patient at the time of operation also affects the wear rate. It appears that wear rate started to accelerate from year 8 onwards. The risk is higher with cups of less than 50mm diameter We conclude that it is advisable to review closely those patients with the ACS cup implanted. Revision surgery should be considered if eccentric wear started to be seen on Xray to avoid complicated procedure.
The shape of the femoral canal is variable, infact more variable than most contemporary designs of femoral components would suggest or accommodate. Clinical and experimental studies of total hip replacement have demonstrated the need for a close geometric fit between the femoral component and the supporting bone for a durable implant fixation. In order to provide a basis for design and selection of femoral components in future, we undertook an anthropometric study of proximal femoral geometry on Indian specimens. 74 cadaveric femorae were studied to analyze the difference in the endosteal and periosteal geometry between Indian and Western population. Standard extra-cortical and endosteal dimensions were determined by direct measurements of radiographs. To enable comparison standard horizontal and vertical axis were established using the geometric center of lesser trochanter and the bisecting axis of the medullary canal at the level of the isthmus. Statistically significant differences were found for the following measurements: Femoral head offset, Width at lesser trochanter, Width at lesser trochanter-20mm, Proximal border of isthmus, Neck shaft angle.
All the measurements were done by two independent observers and averaged. From the standard radiographs, the sacral slope (SS), the acetabular frontal inclination (AFI), and the acetabular sagittal inclination (ASI) were measured in standing, sitting, and lying positions. From the CT scan sections, the anatomical ante-version (AA) was measured in lying position on axial images according to Murray. The results were compared to a previously described protocol replicating standing and sitting positions: CTscan sections were oriented according to sacral slope.
Revision surgery is generally recommended for recurrent dislocation following Total hip arthroplasty (THA). However, dislocation following revision THA continues to remain a problem with further dislocation rates upto 28% quoted in literature. We present early results of one of the largest series in U.K. using dual mobility cemented acetabular cup for recurrent hip dislocation. We retrospectively evaluated 40 patients where revision of hip replacement was performed using cemented dual mobility acetabular prosthesis for recurrent dislocations from March 2006 till August 2009 at our district general hospital by a single surgeon (senior author). The series comprised of 13 men and 27 females with average age of 73.4 years (49-92). The mean follow-up period was 23 months. (36 months –6 months). All the hips that were revised had 3 or more dislocations, some them more than 10 times. The cause of dislocation was multifactorial in majority of cases including acetabular component malpositioning mainly due to loosening and wear. A cemented dual mobility cup was used in all cases. In six cases the femoral stem was also revised.Introduction
Methods