Aims. Limited implant survival due to aseptic cup loosening is most commonly responsible for revision total hip arthroplasty (THA). Advances in implant designs and materials have been crucial in addressing those challenges. Vitamin E-infused highly cross-linked polyethylene (VEPE) promises strong wear resistance, high oxidative stability, and superior mechanical strength. Although VEPE
Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation. This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months’ follow-up. 3D models of each patient’s prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model’s sensitivity, specificity, and area under the curve (AUC).Aims
Methods
Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data. We analyzed the FOs measured on AP hip and pelvis radiographs in a prospective consecutive series of 55 patients undergoing unilateral primary THA for hip osteoarthritis. To determine sample size, a power analysis was performed. Patients’ position and X-ray beam setting followed a standardized protocol to achieve reproducible projections. All images were calibrated with the KingMark calibration system. In addition, a geometric model was created to evaluate both the effects of leg position (rotation and abduction/adduction) and the effects of X-ray source position on FO measurement.Aims
Methods
The use of cementless acetabular components is currently the gold standard for treatment in total hip arthroplasty (THA). Porous coated cups have a low modulus of elasticity that enhances press-fit and a surface that promotes osseointegration.
This study reports the mid-term results of total hip arthroplasty (THA) performed using a monoblock acetabular component with a large-diameter head (LDH) ceramic-on-ceramic (CoC) bearing. Of the 276 hips (246 patients) included in this study, 264 (96%) were reviewed at a mean of 67 months (48 to 79) postoperatively. Procedures were performed with a mini posterior approach. Clinical and radiological outcomes were recorded at regular intervals. A noise assessment questionnaire was completed at last follow-up.Aims
Patients and Methods
Porous tantalum is a highly osteoinductive biomaterial, initially introduced in orthopedics in 1997, with a subsequent rapid evolution of orthopedic applications. The use of porous tantalum for the acetabular component in primary total hip arthroplasty (THA) has demonstrated excellent short-term and mid-term results. However, long term data are scarce. The purpose of this prospective study is to report the long-term clinical and radiological outcome following use of an uncemented porous tantalum acetabular component in primary THA with a minimum follow-up of 17.5 years, in a previously studied cohort of patients. We prospectively followed 128 consecutive primary THAs in 140 patients, between November 1997 and June 1999. A press-fit porous tantalum monoblock acetabular component was used in all cases. The presence of initial gaps in the polar region, as sign of incomplete seating of the
Modern prosthetic stem construction strives to achieve the attractive goals of stress shielding prevention and optimal osteointegration. PhysioLogic stem is a new generation composite isoelastic femoral stem consisting of titanium core sheathed in implantable PEEK polymer and coated with titanium layer. This construction combines the benefits of both stress shielding prevention, due to its elasticity under bending load corresponding closely to that of natural bone, and rapid osteointegration, due to the stem's titanium coating. The aim of this study is long-term clinical progress evaluation and retrospective analysis in patients undergoing primary PhysioLogic stem implantation at our institution. From 1998 to 2003, we performed 51 primary total hip arthroplasty (THA) operations with implantation of PhysioLogic Stem at our institution. Indications for THA included osteoarthritis (21), hip dysplasia (14), rheumatoid arthritis (10), and femoral neck nonunion (6). In all patients we used totally uncemented system — PhysioLogic Stem and
There are many types and articulating surfaces in acetabular cups. Most of the designs currently available are modular, the liner snapping into a locking mechanism of some type. These modular inserts may be polyethylene, usually highly crosslinked polyethylene, or ceramic. Metal shells used in metal-on-metal devices are usually of a monoblock design. The elliptical monoblock design has been available for 20 years and was originally made of Titanium with a compression molded polyethylene liner. Tantalum (trabecular metal) was used as the shell material in the more recent designs and the polyethylene is actually molded directly into the tantalum framework. Monoblock acetabular components have a number of advantages. They do not allow access to the ilium because there are no holes in the socket shell with the monoblock construct. They require no locking mechanism which may increase metallic debris. No back surface liner wear can occur because all motion is eliminated at the liner/shell interface. However, because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5 mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. Results with over 258
There are many types of articulating surfaces in uncemented acetabular cups. Most of the designs currently available are modular, with the shell snapping into a locking mechanism of some type. An Elliptical Monoblock design has been available for 15 years and was originally made of titanium with a factory assembled compression molded polyethylene liner. Porous tantalum (trabecular metal) was used as the shell material in a subsequent more recent design and in this design the polyethylene is actually molded directly into the tantalum framework. Monoblock acetabular components do not allow particulate access to the ilium via screw holes and require no surgeon assembled locking mechanism which may increase backside wear and metallic debris. There are no holes in the socket because of the monoblock construct. Because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. The Elliptical shape of the cup makes the mouth of the acetabular component 2mm greater than the dome so that an exceptionally strong acetabular rim fit results. Results will be reported from two major institutional series with a minimum 10-year follow-up (range 10–15 years). No pelvic osteolysis was not seen in any patient in either series. In the HSS series of 250 cases with minimum 10 year follow up there were 4 revisions for instability but none for mechanical failure. There were three femoral revisions for loosening but the cup was intact and not revised in these patients. Utilising the Livermore measurement method polyethylene wear averages 0.8mm per year (0.6mm-1.3mm) and there have been no revisions for wear. Radiographic evaluation demonstrates stable bony interface in all patients. In a Mayo series of prospectively randomised patients also at minimum 10 years there was no lysis and only one case of aseptic loosening in a beaded titanium cup. At minimum 10-year follow up two similar elliptical monoblock cementless acetabular component designs with compression molded polyethylene have confirmed the theoretical advantages of this design concept and demonstrate long term results that have been excellent to date.
There are many types and articulating surfaces in acetabular cups. Most of the designs currently available are modular, the liner snapping into a locking mechanism of some type. These modular inserts may be polyethylene, usually highly crosslinked polyethylene, or ceramic. Metal shells used in metal on metal devices are usually of a monoblock design. The elliptical monoblock design has been available for 20 years and was originally made of Titanium with a compression molded polyethylene liner. Tantalum (trabecular metal) was used as the shell material in the more recent designs and the polyethylene is actually molded directly into the tantalum framework. Monoblock acetabular components have a number of advantages. They do not allow access to the ilium because there are no holes in the socket shell with the monoblock construct. They require no locking mechanism which may increase metallic debris. No back surface liner wear can occur because all motion is eliminated at the liner/shell interface. However, because of this absence of screw holes there is an inability to visualise the floor of the acetabulum and perfect coaptation between the shell and the acetabular floor may not occur. The presence of dome gaps of greater than 1.5mm have been noted in 5% of these components but these have not compromised implant stability and in a review of over 600 cups there has been no change in implant position. The elliptical shape of the cup makes the mouth of the acetabular component 2mm greater than the dome so that an exceptionally strong acetabular rim fit results. Results with over 258
Pure tantalum has been proposed in orthopaedic surgery. Its chemical and physical properties have been widely studied in the past. From pure tantalum is obtained a spongy structure (Trabecular Metal Technology: TMT) that shows a full thickness porosity which is 2–3 times higher compared to other surfaces available for bone ingrowth with a three-dimensional porous arrangement in rough trabeculae. Pores (average diameter of 650 mm) are fully interconnected and represent 75–80% of the whole volume. TMT acetabular components have an elliptical shape and have an irregular external surface which both allow an optimal mechanical fit. We retrospectively reviewed 212 cases of monoblock porous tantalum acetabular cup (Hedrocel, Stratec) implanted between 1999 and 2003 in a single centre with a minimum follow-up of 9–10 years; There were 98 men and 114 women, with an average age of 65 years. They all underwent primary or revision total hip arthroplasty or to acetabular component revision alone. In all patients a monoblock porous tantalum acetabular component with polyethylene directly compression molded into cup, with or without peripheral holes for screws, was implanted. In all primary procedures the same femoral stem (Synergy, Smith and Nephew) was implanted. All patients were evaluated with a clinical examination (Harris Hip Score: HHS) and with standard radiographs of the pelvis preoperatively and 1, 3, 6 months and yearly postoperatively. The stability of the acetabular cup was determined by modified Engh's criteria. The HHS score improved from 42 preoperatively to 94 after one year; at 13 years follow-up it was 95. The subjective outcome was widely satisfying, with the majority of patients experimenting good functional recovery and return to daily activities. Osteointegration of the acetabular component was present in all X-rays controls at one year after surgery. All post-operative evidence of residual bone loss (geodes, bone defects in revisions and in displasia) were no more radiographically evident after 1 year postoperatively as the host bone quickly filled these gaps. We did not observe osteolysis nor progressive radiolucent lines at the latest follow-up. None of the cups was revised, except 3 cases, revised for infection. Both clinical and radiographic results are the same or even superior to those of coated implants. Our experience confirms that trabecular metal tantalum cups can avoid the formation of bone-implant interface membrane and consequently can avoid implant loosening. The most important advantages of TMT
The introduction of a new implant material is not without risk. A series of worst-case scenarios were developed and tested accordingly to answer questions such as: what will happen if the implant is not placed in a good orientation? What will happen to the material after a long implantation time, e.g. 20 or more years?. To reach a higher level of safety, a new approach for the preclinical testing has been taken. The vitamys® material (a novel vitamin-doped HXLPE) followed a severe pre-clinical testing protocol, including mechanical, tribological and biocompatibility testing. The testing includes a comparison of vitamys® vs. standard-UHMWPE and other HXLPE after accelerated ageing for periods equivalent to 20 and 40 years in-vivo. Hip simulator testing was done at inclination angles from 35° to 65° to assess the “forgiveness” of the material for mal-orientation. Comparing the test results to published data, it becomes evident that the vitamin addition and the sequence of the manufacturing steps both have a significant effect of the resulting mechanical, ageing and wear properties. In contrast to UHMWPE or HXLPE without antioxidant, the vitamys material behaves in a very “forgiving” manner: Hip simulator testing of vitamys at high inclination angles and even with severely aged material revealed no increase of wear rates. The vitamys material was first introduced in a
Introduction. Current standard cups of metal on metal resurfacing hip arthroplasty (RHA) have no dome holes and it is very difficult for surgeons to confirm full seating of these cups. This sometimes results in gap formation between the cup and acetabular floor. Although the incidence of initial gaps using modular press-fit cups with dome screw holes has been reported to range from 20 to 35%, few studies have reported the incidence of gap formation with
Introduction. The aim of this study is to report the results of Revision hip arthroplasty using large diameter, metal on metal bearing implants- minimum 2 year follow up. Methods. A single centre retrospective study was performed of 22 consecutive patients who underwent acetabular revision surgery using metal on metal bearing implants between 2004 and 2007. Birmingham hip resurfacing (BHR) cup was used in all patients - monoblock, uncemented, without additional screws in 16 cases and cemented within reinforcement or reconstruction ring in 6 cases. Femoral revisions were carried out as necessary. Results. There were 16 men and 6 women with a mean age of 71 years (51-83). Revision surgery was performed for aseptic loosening in 10, infected primary hip arthroplasty in 8, infected Hemiarthroplasty in 1 and Peri-prosthetic fracture with loosening in 3 patients. A 2-stage revision was performed for all infected hips. One patient died and the remaining 21 patients had clinical and radiological assessment at a mean 35 months (24-60). The mean Harris hip score was 75 (23-98) with 50% good to excellent results. Only 1 patient had further revision to a proximal femoral replacement and constrained cup in 2 stages for recurrent infection at 24 months. There were 2 recurrent infections (both revised for septic loosening) and 1 non-union of trochanteric osteotomy. There were no dislocations in the group. No radiological loosening of implants or metal ion complications have been seen at last follow up. Conclusions. We believe this is the first reported series on the use of large diameter metal on metal bearing surfaces for revision hip arthroplasty. Our series shows satisfactory short to medium term results in this complex group of patients with no component loosenings, despite
Originally introduced in 1997, porous tantalum is an attractive alternative metal for orthopaedic implants because of its unique mechanical properties. Porous tantalum has been used in numerous types of orthopaedic implants, including acetabular cups in total hip arthroplasty. The early clinical results from porous tantalum acetabular cups have been promising. The purpose of this study was to evaluate the presence of bone ingrowth and the incidence of osteolytic lesions in the acetabular cup -at 10 year follow up – in patients who had a total hip arthroplasty with a monoblock porous tantalum acetabular cup. 50 consecutive patients underwent a total hip arthroplasty with a monoblock porous tantalum acetabular component. All patients had computed tomography at an average of 10 years of follow-up. The computed tomography scan used a standard, validated protocol to evaluate bony ingrowth in the cup and for the presence of osteolysis. The computed tomographic scans showed evidence of extensive bony ingrowth, and no evidence of osteolysis. This study reports the 10-year results of a monoblock porous tantalum acetabular cup. This is the first study to evaluate a porous tantalum acetabular cup with the use of computed tomography. These results show that a porous tantalum
Recently,
It is accepted that larger diameter heads are more difficult to dislocate due to the increased distance the head has to travel to come out of the cup. Currently larger femoral heads are being used for their resistance to dislocation however, there remains little reporting on the effect of design of cup on jump distance. Monoblock metal on metal cups, which were designed for hip resurfacing are typically less than a hemisphere internally in order to increase the range of motion (ROM) needed when the femoral neck is retained. This does however also reduce the jump distance. We investigated several designs of cup with a variety of head sizes in order to compare ROM using a computer range of motion tool and a two dimensional jump distance with the cup at 45 degrees inclination. Jump distances were calculated for: Internally hemispheric cups in 28, 32 and 36mm bearing diameters; 28, 40 and 44mm polyethylene liners which were hemispheric but with an additional 2mm cylinder and a 0.7mm chamfer at the equator (Trident, Stryker, Mahwah, USA); 38, 48 and 54mm monoblock metal on metal resurfacing cups with a 3.5mm offset (BHR, Smith and Nephew, Memphis, USA); 40, 48, 58 dual mobility cups with an anatomic rim (Restoration ADM, Stryker, Mahwah, USA). Range of motion modeling was carried out using custom-written software according to a previously published method2 with 5 degrees of pelvic tilt and a standard femoral component. For the present study, range of motion was assessed on a standard stem with a 132° neck angle. Inclination of the cup was set to 45° and anteversion to 20°. For each implant tested, the total ROM was computed in flexion/extension, ab/adduction, and int/external rotation. Components tested for range of motion were: Trident 32, 36, 40 and 44mm Internal Diameter; Hemispheric 28 and 32mm Internal Diameter cups; MITCH TRH MoM
In almost all countries performing Total Hip Replacement (THR), dislocation is one of the major reasons for revision. Hence, in the last years the trend to larger bearings has been observed, following an improve in the bearing materials, the operation technique, and fixation techniques of stem and shell. Larger bearings allow for more range of motion and higher stability than conventional 28 mm bearing couples, leading to a better postoperative mobility. On the other hand, size limitations on the acetabular side are given by the anatomy of the human pelvic bone as well as the deformation and fracture behaviour of the used artificial materials. Therefore, the best solution to be achieved provides a maximum physiological outcome along with a minimised risk of intraoperative and in-vivo failures. Investigating the wall thickness of the metal shell which is press-fitted in the human pelvic bone, the general trend towards a smaller wall thickness yielding an increased compliance can be observed with larger bearing diameters. This may lead to deformations of the metal shell making it difficult for the surgeon to properly introduce the insert. Hence, taking into account that a proper seating of the insert is absolutely necessary when using a ceramic insert in order to avoid point loads, operation time may strongly increase especially when minimal invasive surgery technique is used. With decreasing overall wall thickness of the acetabular components the volumetric stresses increase by definition. Therefore, an optimal component coupling between insert and metal shell is necessary in order to avoid point loads and resulting stress concentrations. With pre-assembled systems, this optimal coupling is reached by the force-controlled insertion of the insert in the metal shell without any prior deformation of the shell. This procedure enables to design acetabular components with a much lower overall wall thickness than conventional systems. As an example, in the case of the DELTA motion system, this overall wall thickness has been decreased to 5 mm allowing e.g. for a usage of a 36 mm bearing couple together with a 46 mm outer diameter of the metal shell. Additionally, the coating of the metal shell allows for direct bone ingrowth. Problems involved with larger bearing diameters may also arise from higher wear rates inducing possibly osteolysis and aseptic loosening. Investigations concerning the wear behaviour of large ceramic bearings have shown that there is no increase in the wear volume with increasing diameter.
Preliminary results using Trabecular Metal (TM) acetabular component (made of tantalum) in primary and in revision total hip arthroplasty are encouraging in few published papers in the literature. Patients and Methods: The outcome and survivorship of a TM revision uncemented acetabular cup were assessed in 85 consecutive patients (Male 48, Female 37, mean age 70,9 years, range 54–92) undergoing revision THA in the time period from 13.5.2004 to 8.6.2006. Years from previous operation to revision arthroplasty was in average of 10,0 years (range 1–23). Acetabular bone defects were assessed using Paprosky grading system.
Introduction: Tantalum
