Introduction. Reoperations to manage unstable total hip arthroplasty are reported with a high failure rate. The
Introduction. The
Aims. Dislocation remains a significant complication after total hip arthroplasty (THA), being the third leading indication for revision. We present a series of acetabular revision using a
BACKGROUND PURPOSES. dislocation is a classical complication in total hip arthroplasty (THA) revision. Cup fixation is the second concern. Since 1998 we routinely use cementless
Treatment of recurrent dislocation: approximately: 1/3 of failures (probably higher in the absence of a clear curable cause). In the US: most popular treatment option: constrained liners with high redislocation and loosening rates in most reports. Several interfaces leading to various modes of failures. In Europe:
Purpose of the study: The concept introduced by Gilles Bousquet is an effective arm against dislocation of total hip arthroplasty (THA), as has been demonstrated in clinical series with a long follow-up. There remain certain questions concerning wear of
Introduction. Polyethylene (PE) wear is clearly linked to total hip arthroplasty (THA) failure, leading to osteolysis and decreasing survivorship rates.
The benefit of
Summary Statment. The dual-mobility cup seems to bring more stability without changing the gait pattern. Introduction. Dislocations and instability are among the worst complications after THA in elderly patient.
Introduction. Upper femoral fractures include intra and extra-capsular fracture (ECF). For intra-capsular fracture (ICF), hemi-arthroplasty (HA) is the most commonly used treatment. Interest in total hip arthroplasty (THA) is growing because THA yields less revision (4% versus 7%) associated to better functional results despite higher dislocation rate (9% versus 3%). Regarding ECF, internal fixation is the reference treatment. THA could represent a relevant alternative. This study evaluates the efficiency of THA using
Mid and long-term follow-up of Charnley total hip arthroplasty (THA) demonstrated good functional results with 85% survivorship at 25-year follow-up. However dislocation still remains an unsolved problem. Dislocation may occur all along the patient and implant life. The aim of this study is to answer the question: does
Dual mobility components for total hip arthroplasty provide for an additional articular surface, with the goals of improving range of motion, jump distance, and overall stability of the prosthetic hip joint. A large polyethylene head articulates with a polished metal acetabular component, and an additional smaller metal head is snap-fit into the large polyethylene. The first such device was introduced for primary total hip arthroplasty by Bousquet in the 1970s, thus, the “French connection”. Dual mobility components have been released for use in North America over the past five years. In some European centers, these components are routinely used for primary total hip arthroplasty. However, their greatest utility may be to manage recurrent dislocation in the setting of revision total hip arthroplasty. Several retrospective series and the Swedish hip registry have shown satisfactory results for this indication at short- to medium-term follow-up times. However, there are important concerns with polyethylene wear, late intraprosthetic dislocation, and the lack of long-term follow-up data. These components are an important option in the treatment of recurrent dislocation in younger patients, revision of failed metal-metal resurfacing, and salvage of failed constrained liners. There are more recent concerns of possible iliopsoas tendinitis, elevated metal levels with one design, and acute early intraprosthetic dislocation following attempted closed reduction. However, a dual mobility component may now be the preferred solution in revision surgery for recurrent hip dislocation.
INTRODUCTION. THA as primary treatment for displaced femoral neck fractures in elderly still remains a prominent concern. Overall dislocation rate after total hip arthroplasty (THA) is reported form 1∼5%. But, it is quiet different in situation of femur neck fracture in elderly. The THA is associated with higher rates of dislocation (8%∼11%) in eldery compared to hemiarthroplasty even though THA showed better clinical and functional scores. Recently resurgence about THA using DMC comes after improvement of manufacturing technology. The aim of this prospective multicenter study is to assess the rates of dislocation and re-operation for displaced femoral neck fractures in elderly with THA with
Dual mobility components for total hip arthroplasty provide for an additional articular surface, with the goals of improving range of motion, jump distance, and overall stability of the prosthetic hip joint. A large polyethylene head articulates with a polished metal acetabular component, and an additional smaller metal or ceramic head is snap-fit into the large polyethylene. In some European centers, these components are routinely used for primary total hip arthroplasty. However, their greatest utility will be to prevent and manage recurrent dislocation in the setting of revision total hip arthroplasty. Several retrospective series have shown satisfactory results for this indication at medium-term follow-up times. The author has used dual mobility components on two occasions to salvage a failed constrained liner. At least one center reports that dual mobility outperforms 40mm femoral heads in revision arthroplasty. Modular dual mobility components, with screw fixation, are the author's first choice for the treatment of recurrent dislocation, revision of failed metal-metal resurfacing, total hips, unipolar arthroplasties, and salvage of failed constrained liners. There are concerns of elevated metal levels with one design, and acute early intra-prosthetic dissociation following attempted closed reduction. Total hip surgeons no longer cement Charnley acetabular components, use conventional polyethylene, autologous blood donation, or a drain; now constrained components join these obsolete techniques! In 2017, a dual mobility component, rather than a constrained liner, is the preferred solution in revision surgery to prevent and manage recurrent dislocation.
In primary total hip replacements there are numerous options available for providing hip stability in difficult situations (i.e. Down's syndrome, Parkinson's disease). We have considered constrained liners in some of these cases. However, in the revision situation in general and in revision for recurrent dislocation situation specifically it is important to have all options available including tripolar constrained liners in order to optimise the potential for hip stability as well as function of the arthroplasty. Even with the newer options available dislocation rates of higher than 10–15% have been reported following revision surgery at institutions where high volumes of revision surgery are performed. Because of the deficient abductors, other soft tissue laxity and the requirement for large diameter cups revision cases will always have more potential for dislocation. In these situations in the lower demand patient, constraint has provided excellent success in terms of preventing dislocation and maintaining implant construct fixation to bone at intermediate- term follow-up. Hence in these situations tripolar constrained liners remains the option we utilise. We are also confident in using this device in cases with instability or laxity where there is a secure well- positioned acetabular shell. We cement a dual mobility constrained liner in these situations using the technique described below. Present indication for tripolar constrained liners: low demand patient, large outer diameter cups, instability with well-fixed shells that are adequately positioned, abductor muscle deficiency or soft tissue laxity, multiple operations for instability Technique of cementing liner into shell: score acetabular shell if no holes, score liner in spider web configuration, all one or two millimeters of cement mantle Constrained Dual Mobility Liner For Dislocation: 56 Hips, 10 yr average f/u, 7% failure of device, 5% femoral loosening, 4% acetabular loosening For Difficult Revisions:101 hips, 10 yr average f/u, 6% failure of device, 4% femoral loosening, 4% acetabular loosening Cementing Liner into Shell: 31 hips, 3.6 yr average f/u (2–10 years), 2 of 31 failuresResults
The dual mobility design concept for acetabular liners is intended to reduce the risk of dislocation and increase range of motion, but the wear pattern of this design is unclear and may have implications in implant fixation. Additionally, the solid back cups do not have the option for supplementary screw fixation, providing an additional smooth articulating surface for the liner to move against. The objective of this study was to assess cup fixation by measuring implant migration. A secondary objective was to evaluate the mobile bearing motion after rotating the hip. Thirty subjects were recruited in a consecutive series prospective study and received Anatomic Dual Mobility (Stryker Orthopedics) uncemented acetabular components with mobile bearing polyethylene liners through a direct lateral approach. Femoral stems were cemented (Exeter) or uncemented (Accolade, Stryker Orthopedics). The femur, acetabulum, and non-articulating surface of the polyethylene liner were marked with tantalum beads. Radiostereometric analysis (RSA) exams were performed post-operatively and at 6 weeks, 3, 6, months, and at 1 year. At the 1 year exam, a frog leg RSA exam was performed to assess the mobility of the cup compared to its position during a supine exam.Introduction
Methods
The concept of stainless steel
Dislocation is the most common indication for further surgery following total hip arthroplasty (THA) when undertaken in patients with a femoral neck fracture. This study aimed to assess the complication rates of THA with dual mobility components (THA-DMC) following a femoral neck fracture and to compare outcomes between THA-DMC, conventional THA, and hemiarthroplasty (HA). We performed a systematic review of all English language articles on THA-DMC published between 2010 and 2019 in the MEDLINE, EMBASE, and Cochrane databases. After the application of rigorous inclusion and exclusion criteria, 23 studies dealing with patients who underwent treatment for a femoral neck fracture using THA-DMC were analyzed for the rate of dislocation. Secondary outcomes included reoperation, periprosthetic fracture, infection, mortality, and functional outcome. The review included 7,189 patients with a mean age of 77.8 years (66.4 to 87.6) and a mean follow-up of 30.9 months (9.0 to 68.0).Aims
Methods
Introduction. Patients undergoing primary total hip arthroplasty (THA) with prior lumbar spine fusion (LSF) are at high risk for instability with reported incidence of dislocation as high as 8.3%. The use of
Dual mobility is a French concept that appeared in the 1970s and was initially intended to reduce dislocation rates. In recent years, this concept has evolved with new HA titanium spray coatings, new external macrostructures, and better-quality polyethylene. This has allowed to extend the indications to younger and therefore active populations. The objective of our work is to analyze at least 10 years a homogeneous and continuous series of 170 primary total hip replacements associating a latest generation Novae Sunfit. ®.
Aims. With increasing burden of revision hip arthroplasty (THA), one of the major challenges is the management of proximal femoral bone loss associated with previous multiple surgeries. Proximal femoral arthroplasty (PFA) has already been popularized for tumour surgeries. Our aim was to describe the outcome of using PFA in these demanding non-neoplastic cases. Methods. A retrospective review of 25 patients who underwent PFA for non-neoplastic indications between January 2009 and December 2015 was undertaken. Their clinical and radiological outcome, complication rates, and survival were recorded. All patients had the Stanmore Implant – Modular Endo-prosthetic Tumour System (METS). Results. At mean follow-up of 5.9 years, there were no periprosthetic fractures. Clearance of infection was achieved in 63.6% of cases. One hip was re-revised to pseudo arthroplasty for deep infection. Instability was noted in eight of the hips (32%), of which seven needed further surgery. Out of these eight hips with instability, five had preoperative infection. Deep infection was noted in five of the hips (20%), of which four were primarily revised for infection. One patient had aseptic loosening of the femoral component and awaits revision surgery. The Kaplan-Meier survivorship free of revision of any component for any reason was 72% (95% confidence interval (CI) 51.3% to 92.7%), and for revisions of only femoral component for any reason was 96% (95% CI 86.3% to 105.7%) at five years. Conclusion. Dislocation and infection remain the major cause for failure, particularly in patients with pre-existing infection. The use of
The main causes of total hip arthroplasty (THA) revisions are loosening and instability. Use of a
Introduction. Dislocation as a primary cause of revision has been on the increase in Sweden (14% in 2014). The increasing use of
Introduction. Revision procedures for unstable total hip arthroplasty have been reported with high failure rates. Many options have been proposed in such challenging cases, including dual mobility. The purpose of this retrospective study was to assess the clinical and radiologic features associated with the
Introduction. Total hip arthroplasty (THA) instability is well documented to be more common in specific demographic groups. We report a retrospective analysis of the use of a dual mobility implant for primary hip replacements in selected patients at risk for dislocation. The aim of this study was to assess the long-term clinical and radiologic features associated with the
Introduction. The published results of the use of a
Dislocation after total hip arthroplasty in individuals treated for acute hip fracture is up to 10 times more frequent than in elective patients. Whilst approach plays a role, the effect of head sizes in conventional THA and
Introduction. 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. Methods. 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
Introduction. Few studies are published about total hip arthroplasties (THA) in Parkinson's disease as it is often considered as a contraindication for hip replacement. THA for fracture is reported as a high complication rate surgery. Regarding bone quality these cases are assimilated to elderly patients and cemented implants are generally preferred. However, due to the improved length and quality of life, we face more potential indications for joint replacement. The aim of this study is to report our experience of cementless dual mobility implants for primary THAs for osteoarthrosis and THA revisions focusing on the risks and benefits of surgery. Material and methods. 65 THA were performed in 59 patients (34 men, 25 women, mean age 73 years, 55–79). Mean latest follow-up was 8,3 years (4–14). Indications were 42 primary THA (osteoarthrosis) and 21 revisions (11 recurrent dislocation, 6 acetabular PE wear, 4 femoral loosening). Surgical approach was always antero-lateral. All patients were implanted with the same
Introduction. Biological repair of acetabular bone defects after impaction bone grafting (IBG) in total hip arthroplasty could facilitate future re-revisions in case of failure of the reconstruction again using the same technique. Few studies have analysed the outcome of these acetabular re-revisions. Patients and Methods. We analysed 34 consecutive acetabular re-revisions that repeated IBG and a cemented cup in a cohort of 330 acetabular IBG revisions. Fresh-frozen femoral head allografts were morselized manually. All data were prospectively collected. Kaplan-Meier survivorship analysis was performed. The mean follow-up after re-revision was 7.2 years (2–17). Intraoperative bone defect had lessened after the first failed revision. At the first revision there were 14 hips with Paprosky 3A and 20 with Paprosky type 3B. At the re-revision there were 5 hips with Paproky 2B, 21 with Paprosky type 3A and 8 with type 3B. Lateral mesh was used in 19 hips. Results. The mean Harris Hip Score improved from 45.4 (6.7) to 77.1 (15.6) at final follow-up. The radiological analysis showed cup migration in 11 hips. The mean appearance time was 25 months (3–72). Of these, migration in three cups was progressive and painful requiring re-revision. Cup tilt was found in all migrated hips. There were one dislocation requiring a cemented
The selection of an acetabular component for primary hip arthroplasty has narrowed significantly over the past 10 years. Although monoblock components demonstrated excellent long-term success the difficulty with insertion and failure to fully appreciate full coaptation of contact with the acetabular floor has led to almost complete elimination of its utilization. Modular acetabular components usually with titanium shells and highly crosslinked polyethylene are by far the most utilised today. This is particularly true with mid-term results demonstrating excellent wear rates and extremely low failure rates and the concern of possible mechanical failure of highly crosslinked polyethylene not being a clinical problem. Ceramic liners are also used but problems with squeaking articulations and liner chipping have made highly crosslinked polyethylene the preferred liner material. Metal-on-metal except in surface replacement arthroplasty is rarely used in primary hip arthroplasty. With instability in total hip replacement still being a significant and the leading cause of revision hip replacement the dual mobility articulation has emerged as an increasingly used acetabular component. This is composed of either a monoblock cobalt chrome socket articulating with a large polyethylene liner into which the femoral head is constrained. The polyethylene liner becomes essentially a larger femoral head articulation and hip stability is significantly improved. A modular dual mobility can also be utilised with a titanium shell and a cobalt chrome liner inserted into the shell and then a dual mobility articulation. In a recent series of 182
The ideal operative treatment of displaced sub capital femoral fractures in the elderly is controversial. Recently, randomised controlled trials have suggested a better outcome with the use of total hip arthroplasty (THA) to treat displaced intra capsular fractures of the femur for elderly patients in good health. More recently the concept of
THA in patients with acetabular bone defects is associated with a high risk of dislocation.
Dislocation post THA confers a higher risk of re-dislocation (Kotwal et al, 2009). The
Instability continues to be a troublesome complication after THA and has been reported to be the main indication for revision in the United States, accounting for 22.5% of revisions. Risk factors associated with dislocation include: age of 75 years or older, body mass index (BMI) of 30 kg/m2 or greater, alcohol abuse, and neuro-degenerative diseases such as multiple sclerosis or Parkinson's disease. Dual-mobility articulations have become an increasingly popular option for these “at risk” primary THAs. Few studies have assessed their use in this complex patient population. The purpose of this study was to assess dislocation rate, radiographic outcomes and complications of the dual-mobility articulation in the setting of primary THA for patients at high risk for dislocation at a minimum follow up of 2 years. We retrospectively reviewed 151 dual mobility acetabular components, that had been performed using a single design (ADM Stryker, Mahwah, NJ) between 2010 and 2014 at a single institution by a single surgeon. The mean age at time of index surgery was 82 years (range, 73–95), 114 patients were female, and mean BMI was 26.2 kg/m2 (range, 16.1–60.9). Dislocation rate and complications associated with
Abstract. Introduction. Dislocation post THA confers a higher risk of re-dislocation (Kotwal et al, 2009). The
Dislocation is a particular problem after total hip replacement in femoral neck fractures and elderly, especially female, patients. The increased rate of dislocation in this population is probably due to significant ligamentous laxity in these patients and poor coordination and proprioception. Another population of patients with increased propensity for dislocation is the revision hip replacement patient. Current dislocation rates in these patients can approach 10% with conventional implant systems. The Dual Mobility total hip system is composed of a cobalt chrome acetabular shell that has a grit blasted, beaded and/or hydroxyapatite coating to improve bone ingrowth. The polyethylene liner is highly crosslinked polyethylene and fits congruently into the cobalt chrome shell and acts like a large femoral head (usually > 40 mm). The femoral head attached to the trunnion is usually 28 mm. The femoral head snaps into the polyethylene liner to acts as a second protection against dislocation. Indications for the Dual Mobility socket are in the high risk for dislocation patient and particularly in elderly, female patients. It is also indicated in patients with neuromuscular disease who are at more risk to dislocate. To date 237
With increasing burden of revision hip arthroplasty, one of the major challenge is the management of bone loss associated with previous multiple surgeries. Proximal femoral replacement (PFR) has already been popularised for tumour surgeries. The inherent advantages of PFR over allograft –prosthesis system, which is the other option for addressing severe bone loss include, early weight bearing and avoidance of non-union and disease transmission. Our study explores PFR as a possible solution for the management of complex hip revisions. Thirty consecutive hips (29 patients) that underwent PFR between January 2009 and December 2015 were reviewed retrospectively for their clinical and radiological outcomes. The Stanmore METS system was used in all these patients. Mean age at the index surgery (PFR) was 72.69 years (range 50–89) with number of previous hip arthroplasties ranging from 1–5. At mean follow up of 32.27 months, there were no peri-prosthetic fractures and no mechanical failure of the implants. Clearance of infection was achieved in 80% of cases. There was 1 early failure due to intra-operative perforation of femoral canal needing further revision and two were revised for deep infection. Instability was noted in 26.7% (8) of the hips, of which, 87.5% (7) needed further revision with constrained sockets. Out of these 8 hips with instability, 5 had pre-operative infection. Deep infection was noted in 20% (6) of the hips, of which, 5 were primarily revised with PFR for septic loosening. However, further surgeries were essential for only 3 patients. One patient has symptomatic aseptic acetabular loosening and 1 had asymptomatic progressive femoral side loosening (lost to follow up). Severe proximal femoral bone loss in complex revision arthroplasties has necessitated the use of PFR prosthesis. Our study supports the fact that PFR is probably a mechanically viable option for complex revisions. Significant numbers of dislocations and infections could be attributed to the poor soft tissue envelope around the hip. Further surgical techniques in the form use of
Introduction. The rapidly expanding aging population in the UK are living longer than ever before, which is reflected by the rising number of relatively fit and healthy people that sustain fracture NOF (neck of femur). According to current NICE (National institute for health clinical excellence) guidelines a large proportion of fracture NOF patients meet the requirements to have a total hip arthroplasty (THA) for this injury. Dislocation rate of THA can be as high as 20% for patients with fracture NOF, which is a disastrous complication in these vulnerable patients. Numerous techniques have been adopted to minimise the risk of dislocation. The use of dual mobility (tripolar) acetabular components is one such strategy with a proven track record in the literature that is employed by surgeons at our institute. Objectives. To assess the dislocation rate in patients with fracture NOF treated with dual mobility (tripolar) THAs in our unit. Method. Retrospective study analyzing clinical notes and radiographs for dislocation rate, cup inclination, and limb length discrepancy. Results. A total of 17 patients with fracture NOF were treated with biarticular THAs during a 3½ year study period, with an average follow up of 22 months. Mean cup inclination was 42°, with mean limb length discrepancy of 3.4 mm. All patients mobilized comfortably without the use of walking aids. There have been no dislocations in our study group to date. Conclusions. This small series has excellent results, with a 0% dislocation rate, in treating fracture NOF patients with dual mobility (tripolar) acetabular cups. This is comparable to larger studies in the literature.
INTRODUCTION. Dislocation is one of the most important complications in THA.
INTRODUCTION. The Articular Surface Replacement XL system (ASRXL) with metal-on-metal (MoM) of the articular surfaces was produced by DePuy Orhopaedics since 2003 for total hip replacement. In 2010 following the notification received from the National Joint Registry (NJR) of England and Wales concerning the excessive failure rate of the ASR system (approximately 13% at 5 years), the DePuy send the recall of the product. All operated patients were checked. MATERIALS AND METHODS. We enrolled in our Followup 106 patients (51 males, 55 females, mean age 63.6) with a total of 107 implants (one is a bilateral case), subjected with clinical and instrumental investigations. The controls were performed annually; for the patients who presented positive clinical-instrumental condictions and values of Chromium (Cr) and Cobalt (Co)> 7 mg /l it has been proposed followup closer, every 6 months for the entire life of the implant. For the evaluation of the cases in our study, we used the following scales:. Clinical Score: Harris Hip Score (pain and functional limitation). Rx score:. 0 normal;. 1 bone resorbtion and mobilization. Ultrasound score:. 0 none. 1 fluid collection <20 mm. 2 fluid collection >20 mm. 3 solid mass: metallosis. Blood metal levels of Cr-Co (μg/l = parts per billion = ppb). Normal < 3 ppb. Alert 3–7 ppb. Pathological >7 ppb. The analysis of ionemia was made at the Clinical Chemistry at Charing Cross Hospital in London. RESULTS. The followup includes 106 patients for a total of 107 hip prostheses. Of these patients, 34.5% (36 patients, 22 women and 14 men, average age 61 years, min. 34 – max. 79), had implant revision with a
Purpose of the study: The purpose of the study was compare dislocation rates of total hip arthroplasties (THA) implanted with a dual-mobility cup versus those implanted with a conventional cup. Material and method: The first series (DM) included 105 patients who underwent first-intention THA implanted by one operator (DS) from January 2005 to June 2007.
Purpose of the study: In 1975, Bousquet and Rambert invented the concept of dual mobility to reduce the risk of dislocation by changing the fixed insert on a Charnley implant to a mobile liner within a metal back shell held onto the femoral head by a retaining collar. This enabled implant recipients to maintain their intense activities without restriction after a first-intention procedure and to overcome muscle deficits after revisions. The screw-on PF stem was introduced in 1985. The purpose of our study was to demonstrate the long-term advantages and failures of this combination. Material and method: This series included 240 hips with a PF stem and a Novae metal back cup. This was a retrospective analysis of a homogenous group of consecutive patients who underwent surgery from 1985 to 1990 (mean follow-up 22 years). Mean age at implantation was 56.7 years. This is the largest series, with the longest follow-up reported to date with dual mobile cups. The main indication was degenerative joint disease (79%) then osteonecrosis (11%). The implant was made of 316 L stainless steel. The PF was composed of the stem, a 22 mm diameter monobloc modular base and a 16 mm diameter neck. The tripodal Novae metal back cup was alumina coated. Preop, intraoperative and postop data were analysed. Clinical and radiographic follow-up (lucent lines, implant position) were noted at last follow-up. The Charnley, PMA, Devane and Sedel scores were noted. Results: The preoperative PMA was 10.8, reaching 16.9 at last follow-up. The Devane score remained unchanged at 3. The mean Brooker score was 1.2. There were no cases with crural pain. Survival at last follow-up was 80%. There were no cases of dislocation, 18 intraprosthetic dislocations (4% at 9.25 years), four revisions of implant wear (1.7% at 19 years), five femoral revisions (2%), two infections (0.8%), nine patients lost to follow-up (4%) and 100 deaths. Conclusion: The PF stem has a remarkable survival. The overall survival is comparable with series having an equivalent follow-up. The dislocation rate was zero, demonstrating the superiority of the dual mobility concept. There were several intraprosthetic displacements which came later than with Profil stems (role of the neck on the lip). The main complication was acetabular loosening, attributed to insufficient secondary fixation, improved later by adjunction of hydroxyapatite. Wear of the
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
Osteolysis induced by UHMWPE debris has historically been one of the major causes of long term failure of TJR. An increase in concentration of polyethylene particles in the peri-prostheic tissue has been linked to an increased incidence of osteolysis. The dual mobility hip bearing concept mates a femoral head into a polyethylene liner which has an unconstrained articulation into a metal shell. The wear mechanism of the dual mobility hip bearing is distinct from a constrained single articulation design, which may result in a difference in wear debris particles. The aim of this study is to evaluate wear debris generated from a dual mobility hip and compare it to a conventional single articulation design when both are manufactured from sequentially crosslinked and annealed polyethylene. The dual mobility hip (Restoration ADM) incorporated a 28mm CoCr femoral head into a polyethylene liner that articulates against a metal shell (48mm ID). The conventional hip (Trident®) mated a 28mm CoCr femoral head against a polyethylene liner. The polyethylene for all liners was sequentially crosslinked and annealed (X3). A hip joint simulator was used for testing at a rate of 1 Hz with cyclic Paul curve physiologic loading. A serum sample from each testing group was collected. Serum samples were protein digested following the published process by Scott et al. The digested serum was then filtered through a series of polycarbonate filter papers of decreasing size and sputter coated with gold for analysis using SEM. Image fields were randomized and wear debris was compared in terms of its length, width, aspect ration, and equivalent circular diameter (ECD). A total of 149 conventional hip particles and 114 dual mobility hip particles were imaged. Results show a majority of particles are of spherical nature and images do not indicate the presence of fibrillar or larger elongated polyethylene debris. Particle length between designs is not statistically different, while all other comparisons show statistical significance (p<0.05). It is hypothesized that the dual mobility hip system reduces the total amount of cross-shear motion on any one articulation, which aids in the reduction in wear. This design feature may be responsible for the slight difference in morphology of dual mobility wear debris when compared to the constrained hip design. The length of the particles was similar, simply indicating a different shape rather than a marked reduction in overall size. The debris generated is this study was from highly crosslinked polyethylene in two different designs, which produced a very significant decrease in quantity of particles when compared to the quantity of debris from conventional polyethylene. The wear debris was of similar length in both designs and so we do not expect any difference in biological response to debris from either device. The dual mobility design has also shown no effect of cup abduction angle on wear demonstrating forgiveness to implant positioning. This advantage, combined with the low wear rate and similar length wear particles, should lead to good clinical performance of
Studies have indicated that the shallow Ultra High Molecular Weight Polyethylene (UHMWPE) acetabular socket or the socket with no head center inset can significantly increase the risk of hip joint dislocation. A previous study suggested the rim loading model in UHMWPE socket and metal femoral head can generate an intrinsic dislocating force component pushing head out of socket. Recently there has been renewed interest in dual mobility articulations due to the excellent stability. The outer bearing couple of the dual mobility articulations are comprised of the UHMWPE femoral head and metal acetabular socket while inner bearing is the locked conventional metal-poly construct. The acetabular socket is also featured by an anatomically shaped head inset wall. The purpose of this study was to theoretically compare the intrinsic dislocating force between conventional metal head on UHMWPE socket articulations and the poly head on metal socket articulations used in the
One-stage revision hip arthroplasty for periprosthetic joint infection (PJI) has several advantages; however, resection of the proximal femur might be necessary to achieve higher success rates. We investigated the risk factors for resection and re-revisions, and assessed complications and subsequent re-revisions. In this single-centre, case-control study, 57 patients who underwent one-stage revision arthroplasty for PJI of the hip and required resection of the proximal femur between 2009 and 2018 were identified. The control group consisted of 57 patients undergoing one-stage revision without bony resection. Logistic regression analysis was performed to identify any correlation with resection and the risk factors for re-revisions. Rates of all-causes re-revision, reinfection, and instability were compared between groups.Aims
Methods