Introduction. Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in the human body after total joint replacement causes serious clinical and biomechanical reactions. Therefore, the wear phenomenon of UHMWPE is now recognized as one of the major factors restricting the longevity of artificial joints. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE. Materials and Methods. In a previous study (Cho et al., 2016), it was found that roundness (out-of-roundness) of the retrieved UHMWPE acetabular cup liner [Figure 1(a)] had a tendency to increase with increasing roundness of the retrieved metal femoral head [Figure 1(b)]. It appears that roundness of the femoral head contributes to increase of wear of the polyethylene liners. We focused on the roundness of femoral head as a factor influencing the wear of polyethylene liner in
Introduction. Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE and the polyethylene wear debris generated in the human body after total joint replacement cause serious clinical and biomechanical reactions. Therefore, the wear phenomenon of UHMWPE in total joint replacement is now recognized as one of the major factors restricting the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE. Materials and Methods. The wear and/or failure characteristics of 33 retrieved UHMWPE acetabular cup liners of hip prostheses were examined in this study. The retrieved liners had an average in vivo duration of 193.8 months (75 to 290 months). Several examples of the retrieved liners are shown in Figure 1. The elasto-plastic contact analyses between metal femoral neck and polyethylene liner and between metal femoral head and polyethylene liner using the finite element method (FEM) were also performed in order to investigate the factors influencing the wear and/or failure mechanism of the polyethylene liner in
Introduction. Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in knee and hip prostheses after total joint replacement is one of the major restriction factors on the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear of UHMWPE. A number of studies have investigated the factors influencing the wear of UHMWPE acetabular cup liner in
The accurate differentiation of aseptic loosening from periprosthetic infection in the painful
Background: Revision total hip replacement is challenging when there is severe proximal bone loss. The Kent
The Huckstep ( Bbraun Medical) interlocking
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 total
Fracture of the femur in association with total hip arthroplasty is a challenging complication that has been well described. A variety of surgical treatment options have been reported. We present our experience of the Kent
We report the result of 46 patients (30 female, 16 male) with periprosthetic femoral fractures who underwent insertion of the Kent
Introduction. This study reports outcomes of 35 revisions of a recalled metal-on-metal (MOM) monoblock prosthesis performed by a single surgeon. Methods. We prospectively collected data on all patients who underwent revision of a recalled metal-on-metal monoblock prosthesis between 2010 and 2015. Average follow-up was 2.5 years post-revision and 6.9 years post-primary procedure. We evaluated the cohort for age, BMI, gender, existence of medical comorbidities, and post-op complications. We compared pre and post-revision cup abduction angles, anteversion angles, combined angles, cup sizes, and Harris Hip Scores. Cobalt and chromium levels were followed throughout the study period for each patient. Results. Thirty-one patients underwent 35 revisions surgeries for pain, high metal ions, infection, aseptic loosening, failure of ingrowth, leg length discrepancy and/or pseudotumor. Two of these revisions were subsequently re-revised – one for continued pain and one for failure involving multiple dislocations, breakage of screws, and acetabular fracture. The survival rate for our revisions to date is 94.3%. Female patients comprised a majority of revisions (54%) despite comprising a minority (28%) of primary hip replacements using the studied prosthesis. Revised patients were an average of 51.8 years of age with a BMI of 31.07. Demographics are included on Table 1. There were five post-operative complications, including 2 infections, 2 dislocations, and one DVT. Cups were revised from a mean abduction angle of 47.5° in primary hips to 42.3° in revisions. Cups were revised from a mean of 53.4 to 57.8. Cobalt and chromium levels were followed in all patients and showed significant decrease after revision (Graph 1). Cobalt levels decreased from an average of 33.7 to 13.1 ng/mL while Chromium levels decreased from an average of 12.4 to 9.2 ng/mL. Harris Hip Scores increased significantly after revision (45.8 to 72.1). Conclusion. This study presents 35 revisions of a recalled monoblock
Previous scientific studies have highlighted how coupling is an important element affecting total hip arthroplasty's survival. This study aims to evaluate whether metal-on-metal (MOM) coupling could be a statistically significant risk factor. The data from the regional joint registry (Registro dell'Impiantologia Protesica Ortopedica, RIPO) was used for analysis. The data collection accuracy of this registry was 97.2% in 2017. We retrospective evaluate all MOM total hip arthroplasties (THAs) implanted in our department between January 01st 2000 and December 31st 2011. We used a control group composed by all other prosthesis implanted in our Department in the same time lapse. We registered 660 MOM THAs. Mean age of patients was 66.9 years. 603 patients have a >36mm head, while 78 a <36 mm one. Neck modularity was present in half of patients. 676 implants were cementless. We registered 69 revisions, especially due to aseptic mobilization (16 THAs), implant breakage (9 THAs) and periprosthetic fracture (6 THAs). The MOM THAs overall Kaplan-Meier survival rate was 87.2 at 15 years, and the difference between MOM THAs and other implants two curves is statistically significant (p<0.05). Male sex is a significant risk factors. Further evaluations are in progress to establish the presence of any additional risk factors. We think weight and/or BMI may be included in this category. Our study confirms the data currently present in the literature regarding a lower survival of metal-on-metal hip prostheses. The male sex is a statistically significant risk factor (p<0.05), while age, head size and modularity of the prosthetic neck are not statistically significant (p>0.05). Any new finds will be presented at the congress venue.
Nine cases of acetabular erosion following insertion of the Monk "hard top"
Elderly patients with a high mortality risk for revision surgery are severely handicapped by a loosened
We report the clinical and operative details of seven cases of fracture of the femoral stem of the Ring TiMESH cementless
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 total
A 70-year-old man with an uncemented metal-on-polyethylene
total
Radiographs are often used to determine the varus/ valgus alignment of the prosthesis in relation to the long axis of femur. This is usually considered to be one of the important parameters in predicting early mechanical failure of the total hip replacement. The measurements made by the University of Dundee X-Ray Analysis Software and skilled manual operators of the varus and valgus angulations of
Because we encountered a high failure rate of the acetabular component of the uncemented, hydroxy-apatite coated, Omnifit total
Introduction: One of the primary complications in total hip and knee arthroplasty is infection. One of the major risk factors for deep periprosthetic infection is wound infection. This alone is associated with a substantial morbidity-increase which, in turn, increases hospital admittance time and therefore adds significant costs to the healthcare system. The aim of this study is to determine whether contamination of instruments used during primary insertion of a prosthesis, can be considered an early indicator for the occurrence of prolonged wound discharge. Early antibiotic treatment could then prevent this and decrease hospital admittance time and costs to the health care system. Material and Methods: During 121 procedures, swabs were taken from the first unused broach at the beginning and at the end of the procedure. Removed material from the bone (acetabulum and femur in the hip joint; femur and tibia in case of the knee joint) was tested for contamination as well. During 50 procedures a control swab was taken. The patients on the ward were also monitored to find out whether prolonged wound discharge occurred and to see after how many days the patients were discharged. Results: In 46 cases (38%) at least one culture showed microbial growth. In the other 75, there was no growth at all. If one of the cultures is positive, there is a 52% risk of prolonged wound discharge. Ifall cultures are negative, this risk is reduced to 13% (Chi-square: PO.001). Patients with a positive peroperative culture have to remain in the hospital for an additional 2.4 days (T-test: P-0.001). Conclusion: Peroperative culturing during primary insertion of a knee or
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 total
The ABG total
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 total
Introduction: Proximal bone resorption is a common problem after total hip arthroplasty. This has been attributed to stress shielding and has been reported to be more pronounced for cemented than for uncemented implants. Aim: To investigate the cortical strain distribution of a new proximal “fit and fill” cementless, titanium, femoral,
Introduction: In case of massive bone defect, femoral stem revision may cause significant problems to the orthopaedic surgeons. The periprosthetic infection introduces a further element of complication which often leads to complex surgical strategies. The aim of this study was to assess the preliminary results of femoral revision with modular resection femoral stems in a selected group of patients with infected total hip arthroplasty and extensive bone defect. Materials and Methods: The study group included five patients (three women – two men) with an average age of 72 years (range 62–81 years). From 2006 to 2008 the patients underwent a prosthetic femoral revision with resection modular stems to treat a septic loosened primary
Ceramic-on-ceramic hip resurfacing offers a bone conserving treatment for more active patients without the potential metal ion risks associated with resurfacing devices. The Biolox Delta ceramic material has over 15 years of clinical history with low wear and good biocompatibility but has been limited previously in total hip replacement to 48mm diameter bearings [1]. Further increasing the diameter for resurfacing bearings and removing the metal shell to allow for direct fixation of the ceramic cup may increase the wear of this material and increase the risk of fracture. Eighteen implants (ReCerf™, MatOrtho, UK; Figure1) were wear tested; six were ⊘40mm (small) and twelve ⊘64mm (large). All small and six large implants were tested under ISO 14242 standard conditions for 5 million cycles (mc) at 30° inclination (45° clinically). The six remaining large implants were tested under microseparation conditions in which rim contact was initiated during heel strike of the gait cycle for 5mc. Cups were orientated at 45° inclination (60° clinically) to allow for separation of the head and cup with a reduced 50N swing phase load and a spring load applied to induce a 0.5mm medial-superior translation of the cup. Wear was determined gravimetrically at 0.5mc, 1mc and every mc after.INTRODUCTION
METHODS
Purpose: Fracture of the neck of the femur in elderly subjects is generally treated by arthroplasty, either using a total or intermediary
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 total
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 total
The Kent hip is a distally-locked femoral stem which was developed to address severe proximal bone loss, severe bony deformity and peri-prosthetic fracture. We reviewed the results of 145 consecutive Kent hips implanted into 141 patients between 1987 and 2000. The indications for implantation were aseptic loosening (75 hips), septic loosening (two), peri-prosthetic and prosthetic fracture (37), severe bony deformity (24), and fracture through a proximal femoral metastasis (seven). The median time to full weight-bearing after surgery was two days and the mean length of follow-up was 5.1 years (2 to 15). Further revisions were required for 13 femoral stems. With removal of the stem for any reason as an end-point, the cumulative survival at five, ten and 15 years was 93%, 89% and 77%, respectively. In patients aged ≥ 70 years, the cumulative survival at 15 years was 92%, compared with 68% in those aged <
70 years. Because of these findings, we recommend the use of interlocking stems in patients aged ≥ 70 years, particularly in those with a peri-prosthetic fracture, for whom alternative methods are limited. Outcome scores and survival data, compared with other systems, indicate that the Kent hip should be used with caution in younger patients.
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: The search for a gold standard uncemented
Purpose: A spacer can be used for two-phase replacement of an infected total
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.
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
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 total
Aims: The purpose of this study is to present our experience with the A.B.G.-I hip system after ten years follow-up. Methods: Prospective study about 162
The aim of this study was to evaluate blood metal ion levels, leucocyte profiles, and serum cytokines in patients with a total hip arthroplasty (THA) involving modular dual-mobility components. A total of 39 patients were recruited, with clinical follow-up of up to two years. Outcome was assessed using the Harris Hip Score (HHS, the 12-Item Short-Form Health Survey (SF-12), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and a visual analogue scale (VAS) for pain. Blood concentrations of cobalt (Co), chromium (Cr), and serum cytokines were measured. Subpopulations of leucocytes were analyzed by flow cytometry.Aims
Patients and Methods
The two-stage revision strategy has been claimed as being the “gold standard” for treating prosthetic joint infection. The one-stage revision strategy remains an attractive alternative option, however, its effectiveness in comparison to the two-stage strategy remains uncertain. A systematic review and meta-analysis was conducted to compare the effectiveness of one- and two-stage revision strategies to prevent re-infection after prosthetic hip infection. Cohort studies (prospective or retrospective) conducted in unselected patients with infection treated exclusively by one- or two-stage revision and reporting re-infection outcomes within two years of revision were retrieved from MEDLINE, EMBASE, Web of Science, Cochrane databases, manual search of bibliographies to March 2015, and email contact with investigators. Data were extracted by two independent investigators and a consensus was reached with involvement of a third. Rates of re-infection were aggregated using random-effect models after arcsine transformation, and were grouped by study and population level characteristics.Background
Methods
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
In the present study we describe the clinical results of the Scientific Hip Prosthesis® (SHP). With the goal of smoothening cement-bone interface stress peaks, the SHP was developed using shape optimization algorithms together with finite element modelling techniques. The resulting shape and cement stresses are seen in Figure 1. The introduction of the SHP prosthesis was performed in a stepwise fashion including a RSA study performed by Nivbrant et al1. RSA studies for prosthetic types that are in long-term use are of great value in predicting the survivorship related to the migration rate and pattern for that specific type of prosthesis. If a stem in a patient shows a much higher migration rate than the typical one, the stem may be identified as at high-risk for early loosening. The study of Nivbrant et al1 revealed unexpectedly high migration values and it was stated that the SHP stem was not the preferred stem to use despite the good Harris Hip Score and Pain score at two years follow-up. In the present study the clinical results of a single surgeon study consisting of 171 hips with a follow-up of 5–12 years were evaluated. The mean follow-up was 8.2 years (5.0–12.0). The survival rate was 98.8% at ten years follow-up for aseptic loosening of the stem. The mean Harris Hip Score at 10 year follow-up was 89.2 ± 7.5. This study therefore indicates that a new prosthetic design may function clinically rather well, despite the relatively high migration rates which have been reported. In case of a RSA study with a new prosthesis it may not be so evident what the expected “typical” migration rate or pattern is. So in order to predict early loosening the typical migration rate has to be known. Perhaps typical migration rates can be established using standardized cadaver migration experiments or computer simulation models techniques. Since these standardized tools are currently not available, the prediction of clinical survival of new prosthetic components remains a challenging task and the interpretation of migration rates with new designs should be considered with much caution.
The worldwide withdrawal of the DePuy Articular Surface Replacement (ASR) device in both its resurfacing and total hip replacement (THR) form on 26 August 2010, after 93,000 were implanted worldwide, has had major implications. The 2010 National Joint Registry for England and Wales quoted figures of 12-13% failure at five years; however these figures may be an underestimate. In 2004 a single surgeon prospective study of the ASR bearing surface was undertaken. Presented are the Adverse Reaction to Metal Debris (ARMD) failure rates of the ASR resurfacing and ASR THR systems. The diagnosis of ARMD was made by the senior author and was based on clinical history, examination, ultrasound findings, metal ion analysis of blood and joint fluid, operative findings and histopathological analysis of tissues retrieved at revision. Acetabular cup position in vivo was determined using EBRA software. Mean follow up was 52 months (24-81) and 70 patients were beyond 6 years of the procedure at the time of writing. Kaplan Meier survival analysis was carried out firstly with joints designated ‘failure’ if the patient had undergone revision surgery or if the patient had been listed for revision. A second survival analysis was carried out with a failure defined as a serum cobalt concentration > 7microgrammes/L (MHRA guideline from MDA-2010-069). Full explant analysis was carried out for retrieved prostheses.Background
Patients and methods
A consecutive series of 30 total hip replacements using a hydroxyapatite (HA)-coated, modular implant (Omnifit) was followed clinically and by roentgen stereophotogrammetric analysis for two years and compared with two control groups, one of 27 cemented Charnley sockets and one of 40 cemented Charnley stems. Omnifit sockets with a central gap between the dome of the socket and the acetabular bone in the postoperative radiographs, migrated less than sockets without such gaps (p = 0.01). After adjustment for patient-related factors (age, gender and weight), no significant difference was found between the two prostheses with respect to micromotion and wear. We conclude that the early fixation of the HA-coated Omnifit prosthesis compares with that of the cemented Charnley prosthesis.
We reviewed 82 primary arthroplasties (in 71 patients) in which cementless porous-coated hip prostheses were used. The mean age of the patients at operation was 52 years (24 to 86); they were followed up for an average of 62.1 months (60 to 66). The diagnosis was avascular necrosis of the femoral head in 35%, fracture of the femoral neck in 24%, primary osteoarthritis in 16% and miscellaneous in 25%. The average preoperative Harris hip score was 56.7 points and the average postoperative score was 83.3 points. Eight hips (10%) had component loosening; four had been revised and four were awaiting revision. In 27 hips (33%) there was a radiolucent line wider than 2 mm in zones 1 and 7. In 55 hips (67%) there was calcar resorption of more than 10 mm. Twenty patients (28%) complained of thigh pain although they had no radiographic evidence of loosening of a component. Factors that may have contributed to the poor clinical and radiographic results were: 1) inadequate surface area for bone ingrowth, particularly on the lateral aspect of the upper part of the prosthesis, 2) poor initial fit of the stem in the metaphysis, which resulted in cantilever motion of the proximal part of the stem about the well-fixed distal stem, and 3) the collar of the prosthesis, which prevented it from subsiding to a naturally stable position and caused damage to the calcar.
This abstract is currently withdrawn to allow an independent review of findings to take place.
Between January 1984 and January 1986, 131 porous-coated anatomic total hip replacements were performed in 119 consecutive patients. Of these, 100 patients (110 hips) who were alive at a minimum of 18 years after replacement were included in the study. The mean age of the patients at surgery was 48.4 years and that of surviving patients at the latest follow-up was 67.8 years. The mean duration of the clinical and radiological follow-up was 19.4 years (18 to 20). The mean Harris hip score initially improved from 55 points before to 95 points at two years after operation, but subsequently decreased to 91 points after six years, 87 points after 11.2 years, and 85 points after 19.4 years. At the final follow-up, 23 hips (18%) of the entire cohort and 21% of survivors had undergone revision because of loosening or osteolysis of the acetabular component and eight hips (6%) of the entire cohort and 7% of survivors for loosening or osteolysis of the femoral component. Only four femoral components (4%) were revised for isolated aseptic loosening without osteolysis and two (2%) for recurrent dislocation. On the basis of these long-term results, the porous-coated anatomic femoral component survived for a minimum of 18 years after operation while the acetabular component was less durable. The findings identify the principles of uncemented joint replacement which can be applied to current practice.
The objective of this study was to evaluate the intermediate term clinical and radiological results of a new short stem hip implant. In 20 consecutive patients suffering from osteoarthritis with 25 affected hip joints (five cases were bilateral), the clinical and radiological results of 25 hip arthroplasties performed in one hospital between October 2009 and May 2014 through a minimally invasive anterolateral approach using a cementless short stem prosthesis type Aida and a cementless cup type Ecofit with a ceramic on ceramic pairing were evaluated prospectively. The median age of patients at time of surgery was 60 years (range, 42–71 years), 15 male (4 were bilateral) and 5 female patients (one was bilateral) were included in the study. The median clinical follow up was 30 months (range, 2–88 months), and the median radiological follow up was 30 months (range, 2–88 months).Aim
Methods
After a few years from its introduction, the limits of the THA became evident, mainly due to high rates of mobilization for polyethylene wear and to the release of metal ions from MOM and MOP couplings. Ceramic bearings were thus introduced in surgery to obtain lower levels of friction and wear. These issues have now been well recognized by several studies, which show that ceramic-on-ceramic joint has the lowest wear rate among various articulations and that ceramic particles induce less macrophage reaction and decrease cytokine secretion, allowing to have little periprosthetic osteolysis. After the first results in the late 70′s and early 80′s, the mechanical reliability was improved due to the manufacturers' efforts to reduce the ceramic fragility evolving average grain microstructure and lowering the degree of impurity. Betterment and standardization of production have led to 3rd generation alumina, Biolox Forte in 1994, that achieved a lower incidence of fracture. The purpose of our study has been to assess long-term follow-up results of alumina-on-alumina 3rd generation ceramic total hip cementless arthroplasty performed at our institution from January 1995 to December 2000. We prospectively followed more than 200 patients operated of THA for primary or secondary hip osteoarthritis analyzing clinical and radiographs features. In this period, the total hip replacement were performed by a single surgeon, who is the senior author (A.T.) in our Institution. All patients were clinically examined to confirm the diagnosis and all of them were checked with a standard plain radiographs in two projections and, when necessary, the radiographic examination was completed by CT scans. The same prosthesis was used in all patients, a 3rd generation alumina COC articulation, composed of a hemispherical titanium alloy cup and a 28-mm alumina ceramic femoral head. The modular ceramic head was fixed to a 12/14 taper cone. Proximally plasma-spray hydroxyapatite coated Ti alloy stems completes the implant features. Modular necks were used in retro or anteversion and varus or valgus offset, allowing changes in neck-shaft angle and giving a perfect intraoperative stability. Clinical assessment was performed using the Merle-D'Aubigne and Postel hip score. Each patient was assessed before surgery, after 30 days, afterwards at 4 months and annually after surgery. The mode of femoral component fixation was radiographically classified as bone ingrowth fixation, stable fibrous fixation or unstable fixation, according to the criteria Engh-Bobyn. Osteolysis was evaluated on the femoral side at each Gruen zone. Osteolysis on the acetabular side was evaluated by DeLee and Chanley zone. Our study has concluded that cementless modular hip arthroplasty with 3rd generation ceramic-on-ceramic bearing, with a 13 to 18 years follow-up, shows an excellent survivorship, in particular for the very low volume release of microparticles during friction, which consequently reduction of cytokine release, thus diminishing the risk of periprosthetic osteolysis and loosening of implant components.
This study reports outcomes of primary and revision total hip arthroplasties of a recalled metal-on-metal (MOM) monoblock prosthesis performed by a single surgeon. We performed a retrospective review of all patients who underwent both primary and revision total hip arthroplasties at our institution between 2006 and 2014. Only those patients who underwent primary recalled MOM monoblock prosthesis placement and/or revision of the recalled prosthesis were included. We evaluated revision group versus non-revision group for age, BMI, gender, existence of medical comorbidities, primary cup abduction and anteversion, primary combined angle, post-operative complications, cobalt and chromium ion levels, and Harris Hip Scores. Student t-test was used to compare groups.Introduction
Methods
In a frail elderly patient a pathological fracture of the femur at the lower end of a loose femoral stem was treated by the retrograde insertion of an intramedullary nail over the tip of the prosthesis.
A prospective, randomised and independently assessed trial of the Ring UPM total hip replacement showed that the quality of the early result was better if the femoral prosthesis was cemented than if it was not. More patients with cemented prostheses were painfree at four months (58% cemented:42% uncemented) and at one year (63% cemented:50% uncemented), but at two years pain relief was equal in both groups. At two years significantly more patients with cemented prostheses could walk without support (96% cemented:62% uncemented, p = 0.01 to 0.05). There is a need for more similar trials to compare the results of contemporary designs of cemented and uncemented total hip prostheses.
Hip implant retrieval analysis is the most important
source of insight into the performance of new materials and designs
of hip arthroplasties. Even the most rigorous
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.
We report the clinical outcome and survival of 100 total hip arthroplasties with Link RS cementless hip prostheses after a mean of 63 months (51 to 93). The average preoperative Merle d'Aubigne hip score was 9.4 points and the average score at the latest follow-up was 15.3 points. Thirteen prostheses have been revised and seven await revision. Survivorship analysis based on intention to revise showed only 68% survival at seven years (95% CI 53% to 81%). The survivals of femoral and acetabular components verified to be loose at surgery were 78% and 89% respectively at seven years. A number of other patients have pain and it seems likely that there will be substantial reduction in these survival figures in the future.
Seven hips with protrusio acetabuli which showed complete or partial resolution of the protrusion after replacement with Ring's prosthesis are reported. It is suggested that this prosthesis offers a simple and effective method of treating painful protrusion into the pelvis; it allows healing of the medial wall of the acetabulum while avoiding many of the hazards of other methods of treatment.
Sixty-five total hip arthroplastics were reinserted after sepsis around the hip, positive cultures being obtained from fifty-six. Although 65 per cent of patients still have their implant in position, only sixteen of sixty-five (25 per cent) show an excellent or good result on a Harris rating. Twenty-three of sixty-five (35 per cent) subsequently required an excision arthroplasty. The indications and contraindications for this procedure are given.
Mechanical wear and corrosion lead to the release of metal particulate debris and subsequent release of metal ions at the trunnion-taper surface. In order to quantify the amount of volume loss to ultimate locations in the surrounding joint space, finite element analysis of the modular head-stem junction is being carried out. The key purpose being to determine a set of optimum design changes that offer the least material loss at the taper-trunnion junction using optimization algorithms such as the gradient based local search (Sequential Quadratic Programming–SQP) and global search (Non-Dominated Sorting Genetic Algorithm-II–NSGA-II). In a broader sense, the principal goal is to work toward the minimization of wear debris produced in the hip joint, thereby resulting in a longer prosthetic lifetime. A numerical approach that simulates wear in modular hip prostheses with due consideration to the taper-trunnion junction on metal-on-metal contacts is proposed. A quasi-static analysis is performed considering realistic loading stages in the gait cycle, and nonlinear contact analysis is to be employed. The technique incorporates a measured wear rate as an input to the finite element model. The simulation of wear is performed by progressively changing nodal coordinates to simulate the wear loss that occurs during surface interaction. The geometry of the worn surface is updated under gait loading. With a given geometry and gait loading, the linear and volumetric wear increases with the number of gait cycles. The continuous wear propagation is discretized and an approximation scheme known as surrogates is to be developed using Artificial Neural Networks (ANN) to reduce the expensive computational simulations during optimization. The model is employed in the optimization schemes coded in MATLAB and linked to the finite element model developed in ANSYS batch mode. The objective function of the optimization problem is to minimize the volumetric wear at taper-trunnion interface under some constraints. By minimizing the volumetric wear, the chance of failure of modular hip implants is also minimized. The FE model developed to reproduce fretting wear is validated through in vitro wear simulations. The important taper design variables considered to have impact on the fretting corrosion performance include; medial-lateral offset, neck length, taper head diameter, trunnion length and diameter, included angle for the head/neck tapers, angle of mismatch or variation in taper trunnion angle, etc. It is expected from clinical outcomes that increased offset and large taper diameter has serious implications in the fretting corrosion behavior primarily because these variables control the bending stresses and strains along the length of the taper. During cyclic loading of the taper, the higher the strain range, the higher will be the relative micromotion at the point of engagement between the stem and head tapers. This research is carried out with the objective to optimize the effects of these geometrical factors at the mating taper interfaces. The developed models have great potentiality for accurate assessment of wear in a range of metal-on-metal (MoM) hip prostheses at the femoral head taper-trunnion junction while substantially reducing the wear and failure rate of prostheses.
A modular neck allows to choose the offset of the femoral head and the degree of anti-retroversion, lateralization and varus-valgus intraoperatively. At the G. Pini Institute we have been using modular necks in custom prostheses since 1989. Excellent results in this application did open the way to a larger use in off-the-shelf prostheses. Modular necks can be now coupled with different stems, leaving the surgeon free to use the preferred prosthetic stem design. Modular necks have been implanted in more than 50,000 in the world. Medium term results in custom prosthesis and the experience in off-the-shelf non-cemented stems are presented, together with further improvements of this technology under study. From 1989 to December 1999, 481 custom stems have been implanted. All patients but ten received modular necks. The prostheses were made of a titanium alloy and HA coated. 61 % of patients had dysplastic oxarthrosis. 372 implants performed between 1989 and 1996 were retrospectively evaluated. Data from off-the-shelf prosthesis, at a shorter follow-up, are also reported. Laboratory data showed that the use of an elliptical Morse cone of the neck reduced wear debris production to less than 1 mg/year. In custom implants, (mean follow-up: 7 years), we did not observe any thigh pain or radiological signs of osteolysis or fretting. Mean leg-length discrepancy was 2.8 cm pre-op and 0.3 cm post-operatively. Off-the-shelf implants also showed good clinical and radiological results. New design modular necks will increase the possible range of motion and provide more solutions for positioning the center of rotation. Modular neck is a safe and reliable solution to obtain the correct position of the center of rotation intra-operatively, without side effects. Applications in off-the-shelf prostheses allow to reduce costs while maintaining the advantages of this technology.
The increasing success rates of total hip replacements (THR) have led to a younger patient population with an increased probability for revision. The survival of revised components is improved by a good bone quality. This has led to an increased interest in bone preserving THR designs. A novel type of THR was developed of which the femoral component is cemented in the neck. The load carrying area of this prosthesis is reduced in comparison with conventional cemented implants. Whether an adequate stability can be achieved was biomechanically evaluated during simulated normal walking and chair rising. In addition, the failure behaviour was investigated. Bone mineral density (BMD) was measured in 5 fresh frozen proximal human cadaver femora. The femoral heads were resected and a 20 mm diameter canal was created in the femoral necks. Bone cement was pressurised in this canal and the polished, taper-shaped prosthesis was subsequently introduced centrally. A servohydraulic testing machine was used to apply dynamic loads up to 1.8 kN to the prosthetic head. Radiostereophotogrammetric analysis was used to measure rotations and translations between prosthesis and bone. In addition, the constructions were loaded until failure in a displacement-controlled test. During the dynamic experiments, the femoral necks did not fail, and no macroscopical damage was detected. The initial stability of the implant did not seem to be sensitive to bone quality. Maximal values were found for normal walking with a mean rotation of about 0.2 degrees and a mean translation of about 120 microns. These motions stabilised during testing. The failure loads in this study varied between 4.1 and 5.5 kN, higher failure loads were associated with higher BMD values. Most specimens showed subtrochanteric spiral fractures. In conclusion, the stability of the prosthetic device may be adequate under dynamic, physiological loading conditions. The static failure loads were relatively low and require further optimisation of the prosthetic implant.
We examined the risk of thrombotic and major
bleeding events in patients undergoing total hip and knee replacement
(THR and TKR) treated with thromboprophylaxis, using nationwide
population-based databases. We identified 83 756 primary procedures
performed between 1997 and 2011. The outcomes were symptomatic venous thromboembolism
(VTE), myocardial infarction (MI), stroke, death and major bleeding
requiring hospitalisation within 90 days of surgery. A total of 1114 (1.3%) and 483 (0.6%) patients experienced VTE
and bleeding, respectively. The annual risk of VTE varied between
0.9% and 1.6%, and of bleeding between 0.4% and 0.8%. The risk of
VTE and bleeding was unchanged over a 15-year period. A total of
0.7% of patients died within 90 days, with a decrease from 1% in
1997 to 0.6% in 2011 (p <
0.001). A high level of comorbidity
and general anaesthesia were strong risk factors for both VTE and
bleeding, with no difference between THR and TKR patients. The risk
of both MI and stroke was 0.5%, which remained unchanged during
the study period. In this cohort study of patients undergoing THR and TKR patients
in routine clinical practice, approximately 3% experienced VTE,
MI, stroke or bleeding. These risks did not decline during the 15-year
study period, but the risk of dying fell substantially. Cite this article:
We have followed up for a period of seven to nine years 100 consecutive arthroplasties of the hip in which an entirely HA-coated implant had been used. The clinical results were excellent and bony incorporation was extensive in all components. No stem became loose or subsided but five cups were revised because of loosening after 3.8 to 5.5 years, having functioned painlessly and shown radiological ingrowth. Revision procedures because of excessive polyethylene wear have been performed on 18 hips and are planned for six more. Two eroded metal backings with worn-through polyethylene were exchanged; six hips showed metallosis without polyethylene wear-through. There were two cases of granulomatous cysts in the groin and 66 hips had osteolysis located periarticularly, in the greater trochanter or in the acetabulum.
We enrolled 98 patients (107 hips) with a mean age of 47 years (SD 8.6) into a prospective study of the Madreporic Lord THR; 34 hips had primary and 73 secondary osteoarthritis. After ten years, the survival rate using revision as the endpoint for failure was 70% (±9) for the cup and 98% (±0.3) for the stem. The combined clinical and radiological survival rates were 46% (±11) and 81% (±10), respectively. Osteoporosis due to stress-shielding was observed in the proximal femur. Hips with radiologically dense bone postoperatively showed the most pronounced bone loss. We recommend continued radiological follow-up of patients with this type of implant to allow revision to be performed before there is severe bony destruction of the pelvis.
Proximal femoral bony deficits present a surgical and biomechanical challenge to implant longevity in revision hip arthroplasty. This work finds comparable primary stability when a distally fixing tapered fluted stem was compared with a conical design in cadaveric tests. Proximal bony deficits complicate revision hip surgery and compromise implant survival. Longer distally fixing stems which bypass such defects are therefore required to achieve stability compatible with bony ingrowth and implant longevity.Summary Statement
Introduction
Twenty-nine patients with thirty pseudarthroses after removal of infected total hip prostheses have been reviewed one to six years later. Six hips still had a discharging sinus. Complete removal of all cement was found to be essential for healing, and various points in the technique of its clearance have been made. In this respect radio-opaque cement was a great advantage, and lateral guttering of the femur was most effective. Compared with the situation before replacement considerable relief of pain was obtained in most patients but there was much less improvement in function.
The ABG stem (Anatomique Benoist Girard, How-medica) was realized of titanium alloy (TA6V) and it was designed to provide anchoring only at the femour’s metaphyseal portion. The long-term stability is achived by osteointegration of the implant at the metaphyseal region, which is coated with hydroxyapatite (HA) crystals. The plasma-sprayed HA coating has a tickness of 60 μm for the stem. The current study presents radiographic outcomes of more than one hundred primary uncemented HA stems with a long-term follow-up. One hundred and eleven ABG hip arthroplasties were evaluated with a mean follow-up of 9.8 years. The radiographical findings have been classified observing Engh’s stability criteria according to Gruen’s subdivision of the periprosthetic femoral zones. Dividing the hips into two different groups (in the first one the prosthesis implanted 11, 12 or 13 years ago and in the second one the prosthesis with a maximum age of 10 years) it’s possible to see as in the first group the radiolucent lines are quite reduced. Among the older prosthesis the percentage of radiolucent lines is 3.1% in zones 3 and 5 and 18.8% in zone 4. For what concerns the younger ones the percentage are 10.1% (zone 3), 21.5% (zone 4) and 15.2% (zone 5). We believe that there is a load transfer from the metaphyseal to the metadiaphyseal portion of the femur without a worsening of the clinical outcomes. The absence of reactive lines and lucencies around the proximal HA-coated portion of the stem supports an excellent circumferential bony ingrowth in the metaphyseal area of the proximal femur. According to these percentages we can say that there’s less presence of radiolucency in the oldest prosthesis and it could be possible to argue that radiolucent lines tend to reduce along the time. This is probably due to the increase of the strength of the stem anchorage.
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.
Infection of total hip replacement still is considered a devastating complication. One-stage revision, meaning complete removal of the implant and thorough debridement of the site together with the insertion of a new prosthesis during the same operation, is desirable because of improved rehabilitation of the patient and reduced costs. Although this method is known since more than 30 years it is not used widely yet because of several related risks: known methods rely on the use of antibiotic-loaded cement, which often has shown insufficient release of the added antibiotic. The carrier may even act as a bed for colonisation with selected bacteria. Osseous conditions presented during revisions prevent interconnection of the cement with the sclerotic bone. The toxic monomers of PMMA and heating during polymerisation causes necroses which may be origin of repeated loosening and new growth of bacteria. Filling the defects with cement provides unfavourable conditions in case of another revision, which has to be expected at a high percentage. To overcome these disadvantages uncemented techniques seem to be favourable. After removal of the implants debridement is performed as in conventional septic surgery. After thorough cleaning and rinsing, bone voids are filled with bone graft using an impaction technique. We use allograft or xenograft bone that is free from antigenic material but intact structures of bone concerning collagen and mineral content. The bone is impregnated with high loads of antibiotic, using a specific incubation technique. There are two options of antibiotic impregnation: vancomycin (“V”) or tobramycin (“T”), the choice being dependent on the causative pathogen isolated. Combinations are possible in cases of mixed infections. The impregnation procedure guarantees high levels of antibiotics at the grafting site for several weeks during which the antibiotic is released into the surroundings. Systemic drug levels are usually undetectable. At the acetabular site we take care that the ground be sufficiently filled with antibiotic graft. Preferably an uncemented cup of hemispherical design is inserted. At the femoral site we prefer implants with a rectangular diameter. This design enables stable press fit contact with the shaft medially and laterally and leaves enough space for graft impaction at the posterior and anterior aspect of the endoprosthesis. Wounds are drained and closed immediately; rehabilitation is performed as after non-septic surgery. Between 1998 and 2004 thirty-seven patients have been revised because of culture-proven infection of hip endoprosthesis. Causative pathogens were Coag.neg. staph (18x), S.aureus (11x), MRSA (4x), enterococci (9x) and other gram-positive pathogens (3x). In 6 hips gram-negative germs were found additionally. All hips could be followed up with a minimum of 2 years and a maximum of 8 years (mean: 4.1 years). Wound healing was uneventful in all cases. Mean hospital stay was 16 days (10–32 days). Rehabilitation was in the range of uncomplicated primary THR in cases with short history of infection (up to 3 months) and prolonged in relation to duration of infection and amount of preceding surgery. In three hips there was recurrence of the infection, diagnosed between 6 and 12 weeks after surgery. In one of them the well-fixed stem had not been exchanged, in another one a technical error had occurred during impregnation of the bone graft. This one could be successfully re-operated using the same technique with appropriately impregnated bone graft, the other two were converted to a girdlestone situation. All other 32 hips showed no sign of infection until the last follow-up. Bone processed in an adequate way represents an excellent carrier for vancomycin and tobramycin. With antibiotic graft compound eradication of pathogens, grafting of bony defects and re-insertion of an uncemented prosthesis may be accomplished in a single operation, making it an ideal tool in one stage non-cemented revision for infected total hip replacement. However, principles of septic surgery need to be observed. We now recommend removing even well-fixed prostheses and taking care, that we implant at least 50cc of well impregnated bone graft. Since the graft gradually is replaced by healthy own bone, improved conditions may be expected even in the case of another revision.
This project assessed the long-term stability of this design at different orientations, by measuring the change in surface strain distribution following its insertion.
Cemented modular metal backed total hip prostheses have the theoretical advantage to allow different inlays to be used. Asymetric or snap inlays are some of the options. First attempts with this kind of implant failed due to PE quality. A novel implant has been specifically designed and constructed for the use of cement. In vitro testing has shown results equal to other cemented cups. Aim of this study is to investigate the first clinical results of this implant with special consideration to intraoperative complications, intraoperative change of inlays, postoperative complications and clinical results.
The implant under investigation was a cemented modular acetabular component (C-MIC, ESKA Implants, Germany). The inlays are manufactured of highly crosslinked polyethylene. The standard protocols regarding DVT prophylaxis and antibiosis for HHS and the Barthel index.
We can conclude that the C-MIC acetabular component is safe to use. Due to limitations of this study we are not able to state if THA is superior to hemiarthroplasty in geriatric patients.
In this meta-analysis we included 32 English-language articles published between January 1975 and June 2004 on the diagnostic performance of plain radiography, subtraction arthrography, nuclear arthrography and bone scintigraphy in detecting aseptic loosening of the femoral component, using criteria based on the Cochrane systematic review of screening and diagnostic tests. The mean sensitivity and specificity were, respectively, 82% (95% confidence interval (CI) 76 to 87) and 81% (95% CI 73 to 87) for plain radiography and 85% (95% CI 75 to 91) and 83% (95% CI 75 to 89) for nuclear arthrography. Pooled sensitivity and specificity were, respectively, 86% (95% CI 74 to 93) and 85% (95% CI 77 to 91) for subtraction arthrography and 85% (95% CI 79 to 89) and 72% (95% CI 64 to 79) for bone scintigraphy. Although the diagnostic performance of the imaging techniques was not significantly different, plain radiography and bone scintigraphy are preferred for the assessment of a femoral component because of their efficacy and lower risk of patient morbidity.
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.
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.
A new conservative hip stem has been designed to address the complex problem of total hip arthroplasty in the younger population. To assess the stability and strain distribution of a new conservative hip stem.Introduction
Objectives
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
Cementless femoral fixation is the gold standard in revision hip arthroplasty. Distal fixation is achieved using either a cobalt chrome or titanium stem. The purpose of this study is to report the long-term survivorship and clinical outcome of a titanium, long-stemmed, load-bearing calcar-replacement femoral component from an independent centre. Eighty-one patients (average seventy-four years, range thirty-five to ninety-one) underwent hip arthroplasty with the Mallory-Head calcar-replacement femoral component, by a single surgeon. There were thirty-eight males and forty-three females with fifty-four hips initially revised for aseptic loosening, thirteen for peri-prosthetic fracture, and five for infection as a two-stage procedure. The implant was used as a primary device in eight patients with deformed proximal femurs. At most-recent follow-up, radiographic analysis was conducted and clinical outcome scoring was assessed using the SF-12, Harris Hip Score, and WOMAC questionnaire for surviving patients. Complications were also reviewed. At a mean follow-up of 7.4 years (range four to fifteen), eight patients have died. There was one deep infection, three DVT’s, and two dislocations in the perioperative period. Six femoral stems have ultimately required another revision surgery for aseptic loosening, two for infection, and 1 for implant fracture at a mean of 5.6 years after initial revision. Four patients required removal of the proximal trochanteric bolt due to breakage or loosening. Overall survival of the implant at five years is 95% (CI 0.87–0.98) and 87% (CI 0.72–0.94) at ten years. The clinical outcome of the Mallory-Head calcar-replacement femoral revision stem is reported from an independent centre. Although the results are encouraging, it would appear that proximal load-bearing fixation with the calcar-replacement stem is not as reliable as distal fixation. The use of a trochanteric bolt was associated with fracture of the greater trochanter or need for a separate surgical procedure for removal. For this series, there was an overall 11% failure rate at a mean follow-up of 7.4 years. The mechanical failure rate is 7.4%. Our overall and mechanical failure rates are somewhat higher than those of the implant developers, who reported 94% overall survival, and a 1.9% mechanical failure rate at a mean follow-up of eleven years.
The neck is the firmer structure of the proximal femur designed to spread the stresses both in compression and tension towards the metadiaphisys and the greater trochanter. Therefore femural neck preserving in total hip arthroplasty allows an optimized stresses’ distribution to obtain both an optimal integration and a subsequent better bone remodelling. The solidity of the structure and the geometric architecture with a femural neck angle of 125° guarantee the maximum primary stability, especially torsional of the stem. At last femural neck retaining allows, when requested, the revision with a richer bone-stock. For the aforementioned reasons since 1979 I proposed the femural neck preservation making a short cementless stem named Biodinamica. From 1983 to 1996 I personally implanted 498 Biodinamica prostheses with very satisfactory results showing a long term survival of the 98% (f.up 13 to 17 years). In 1996 with Ing. Keller it has been created the C.F.P. stem with the T.O.P. acetabular cup as evolution of Biodinamica system. The improvements are critical: materials have changed (from Cr-Co-Mb to Ti alloy), coating and design too. We report clinical and radiographical results of 10 years of C.F.P. implants that showed a further improvement, not only about the prosthesis’ survival, but especially regarding their quality with a 91% excellent clinical outcome. In conclusion we report the 25 years experience retaining the femural neck in hip arthroplasty with Biodinamica (498) and after C.F.P. (445) of a complessive cases of 943 arthroplasty.
Between 1996 and 2003 35 patients have been revised because of culture proven infection of a hip endoprostheses. All hips could be followed with a minimum of 3months and a maximum of 6years.
We compared and quantified the modes of failure and patterns of wear of 11 Mittelmeier and 11 Ceraver-Ostal retrieved alumina-alumina hip prostheses with reference to the corresponding clinical and radiological histories. Macroscopic wear was assessed using a three-dimensional co-ordinate measuring machine. Talysurf contacting profilometry was used to measure surface roughness on a microscopic scale and SEM to determine mechanisms of wear at the submicron level. The components were classified into one of three categories of wear: low (no visible/measurable wear), stripe (elliptical wear stripe on the heads and larger worn areas on the cups) and severe (macroscopic wear, large volumes of material lost). Overall, the volumetric wear of the alumina-alumina prostheses was substantially less than the widely used metal and ceramic-on-polyethylene combinations. By identifying and eliminating the factors which accelerate wear, it is expected that the lifetime of these devices can be further increased.
We reviewed all patients under the care of the senior author, who had undergone Elite Plus hip arthroplasty.
Pre and post-operative radiographs were assessed for adequacy of cementation and evidence of loosening.
Standard UHMWPE Ogee acetabular components were used in all cases. Thirty-six percent of heads were Zirconia. Mean survivorship of all implants 5 years 2 months. The revision rate was 2.7%. Only one revision was performed for femoral component loosening. At latest radiographic review all patients were asymptomatic. However, 31% of femoral components were possibly loose, 5% probably loose and none definitely loose using the Harris criteria. Thirty-four percent of acetabular components were possibly loose, 8% probably loose and 1% definitely loose using Charnley/DeLee criteria.
A cement restrictor, high-viscosity cement and pressurisation were used as standard. Alternative cementation techniques may partially explain early failure seen in other series.
Computational modelling has the potential of becoming a useful tool in assessing revision risk on a patient-specific basis. However, there are many difficulties encountered in generating subject-specific computational models that have unknown influences on such predictions, e.g. accuracy of the anatomical geometry and material properties of the patient. This study compares the influence of these two patient-specific parameters on predictions of revision risk due to aseptic loosening. First, X-rays from seventeen patients were processed using previously developed technique utilising rigid scaling of a generic femur to match selected dimensions from each patient’s post-operative X-ray and, then, the same set of 3D models was obtained by using an automated technique that generates 3D extra-cortical geometries from planar X-rays using a combination of 2D contour extraction and 3D warping of a generic model to match the extracted contour. A cement and cement-metal interfacial damage accumulation algorithm developed previously was used. For each geometric set two types of simulations were performed. First, constant cortical and cancellous bone apparent Young’s moduli were assumed. A second set of simulations used age-dependent Young’s moduli for each bone type. Walking and stair-climbing activities were simulated. Resultant migration of the prostheses was used to indicate revision risk. Factorial analysis has shown that the geometry has a larger influence on resultant migration magnitude for each case; however, unexpectedly, using more realistic geometry weakened the strength of predictions. This is most likely to be due ongoing mesh-induced contact problems.
Stress shielding of the proximal femur occurs in stemmed implants. Resurfacing implant does not invade the intramedullary region. We studied the stress patterns in conventional and nonstemmed designs. FE model geometry was based on standard femur from the international Society of Biomechanics Mesh Repository. Loading simulated for one- legged stance with body weight of 826 N. 2 regions were defined, R1 (40 mm from tip of head) and R2 41 mm–150 mm) of the intramedullary part of the stemmed model's interface with bone. 2 different loading conditions bending and torsion were compared for stress and strain. The FE model was solved with ANSYS version 6.1 on a single processor NT station. With conventional implants, stem shields cortical bone from being loaded. In nonstemmed implants, Von Misses stress contours show a similar distribution as intact bone, transferring loads to the cortical shell but with higher stresses and a maximum displacement of 17.39% higher than that of intact bone. 15–23 mm proximal to R2 and around 110 mm, region of the stem tip, there were higher stress and strain concentrations.Methods
Results
Introduction. Advantages of ceramic materials for
Total hip arthroplasty in adult patients with congenital high dislocation of the hip (DDH, Crowe type IV) presents many challenges. Various reconstruction methods including iliofemoral distraction lenghtening and custom made prosthesis have been reported but the standard technique for dealing with this problem is femoral shortening with a subtrochanteric osteotomy. There are many reports of different subtrochanteric osteotomy techniques with satisfactory results. Since 1999, we have been using the same anatomic reconstruction principles with a proximally hydroxyapatite coated cementless stem. Surgical technique on the femoral side comprises a short oblique subtrochanteric osteotomy and excision of a segment as indicated for a safe reduction. This usually requires extensive soft tissue releases of the pelvifemoral muscles. Gluteus maximus, tensor fascia latae and adductors are routinely released. However, we don’t want to do any more release until it is absolutely necessary. Preserving the attachment of the abductors and iliopsoas are important for eventual functional outcome. They help stabilizing the joint, avoid limping and promote hip flexion during the initial swing phase of the gait and stair climbing. We never resect neither osteotomize the trochanters and, if a release is unavoidable, it is performed proximally. Thus, it is possible to preserve a complete segment of the proximal femur with a soft tissue envelope. This segment allows for better bone stock, prompt healing, reliable proximal fixation through the intact medial calcar and, avoids the complications of trochanteric osteotomy. With this technique we have not observed a femoral revision for any reason in 101 high dislocated hips (in 84 patents), since 1999. Compared with other techniques for arthroplasty in patients with developmental hip dysplasia, this surgical technique has a better functional outcome and a low prevalence of revision. To evaluate the effect of this reconstruction on gait parameters we analyzed the gait cycle in 17 hips in 10 patients before and after the the total hip arthroplasty and compared it with the patients with hip arthroplasty due to primary osteoarthritis. Our aim is to determine the restoration of normal anatomy in DDH patients compared to the patients with total hip arthroplasty but a normal hip anatomy. As a result we have demon-strated that our technique restores normal gait parameters by improving walking speed, lengthening step-stride length, correcting hip and knee flexion and ankle equinus, improving hip and knee stiffness during gait and helps to restore normal gait parameters
Ceramic bearings are widely used in total hip arthroplasty (THR) along with metal and polyethylene bearings. There were several studies in past few years evaluating the advantage of one over the other. The young population with high activity levels has an increased risk of wear debris production at bearing surface and subsequent implant failure. Recently, interest and use of a ceramics with high wear resistance has been growing. Early reports on ceramic on ceramic THR have demonstrated excellent clinical and radiological results. To evaluate clinical, functional and radiological outcomes of cement-less ceramic on ceramic primary total Hip Replacement (THR) in young patients (<50 years age) with diagnosis of avascular necrosis femoral head.BACKGROUND CONTEXT
PURPOSE
We report the long-term radiographic results of the total hip arthroplasty with use of the cementless porous coated Harris-Galante (H-G) stem. Seventy-five consecutive patients, eighty-eight hips formed the basis of this study. Fifty patients were male, twenty-five patients were female, and thirteen patients were bilateral. The mean age of patients at operation was 42 years. They were followed up for an average of thirteen years four months (ten years two months to fourteen years four months). The diagnosis was avascular necrosis of the femoral head in 49 cases, degenerative osteoarthritis in 32 cases. Clinical results were estimated by modified Harris hip score and thigh pain, and radiographic results by periodically checked plain X-ray film. The average Harris hip score increased from 60 points preoperatively to 83 points at the most recent follow-up examination. The hip pain score increased from 31 points to 41 points. Clinically severe thigh pain was observed in 3 cases (4%). In radiographic evaluation, subsidence more than 5mm was seen in 2 cases (2%). Periprosthetic osteolytic lesion was observed in 15 cases (17%), but the lesions do not influence stability of the stem. Femoral stem stability by Engh was stable in 72 cases, fibrous stable in 12 cases, unstable in 4 cases. Pedestal formation, cortical hypertrophy of the distal femur, and stress shielding was observed more than 40%. Subcollar resorption was identified in 29% and ectopic ossification in 15%. Revision of the femoral stem was needed in 4 cases for aseptic loosening. At 10 years probability of survival of the stem using Kaplan-Meyer method was 95.5%. Use of the cementless H-G stem yielded the excellent long-term outcome, but osteolysis and stress shielding would be the main problems to solve.