Aims. To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period. Methods. This is a retrospective study of 166 (154 patients) consecutive cemented,
Summary Statement. Wear of total knee replacement (TKR) is a clinical concern. This study demonstrated low-conformity moderately cross-linked-polyethylene
Purpose of the study. Assessing medium term outcome of medial Uni compartmental replacement and whether there is a difference in outcome between mobile and
Aim: This study investigated the difference in proximal tibial cortical strain distribution using a fixed or mobile bearing design for TKA. Methods: Eight fresh frozen human cadaver tibias were used. The strain magnitude and distribution on the anterior cortex of the proximal tibia during axial and rotational loading of the knee were measured with a quantitative full-field strain measurement technique (Electronic Speckle Pattern Interferometry). First, strain distributions of the intact knee were acquired. Subsequently, strain distributions after implementation of conventional and mobile bearing PCL retaining total knee implants (Scorpio®) were measured. Results: Under each loading condition, the minimum principal strain was greater in magnitude as compared to the maximum principal strain. Under 1′500 N axial loading, the resulting minimum principal strain magnitude and orientation was nearly identical between the mobile bearing configuration (500 ± 287 με), and the
Introduction Movement between the polyethylene insert and the metal tibial tray in modular
This study investigated the difference in proximal tibial cortical strain distribution using a fixed or mobile bearing design for TKA. Eight fresh frozen human cadaver tibias were used. The strain magnitude and distribution on the anterior cortex of the proximal tibia during axial and rotational loading of the knee were measured with a quantitative full-field strain measurement technique (Electronic Speckle Pattern Interferometry). First, strain distributions of the intact knee were acquired. Subsequently, strain distributions after implantation of conventional and mobile bearing PCL retaining total knee implants (Scorpio®) were measured. Under each loading condition, the minimum principal strain was greater in magnitude as compared to the maximum principal strain. Under 1,500 N axial loading, the resulting minimum principal strain magnitude and orientation was nearly identical between the mobile bearing configuration(500 ± 287m;e;), and the
The purpose of this study was to compare the clinical and radiological results of the PFC flex mobile bearing design with those of the LPS flex
Introduction and Aims:
Abstract. Introduction. Medial fix bearing unicompartmental knee replacement (UKR) designs are consider safe and effective implants with many registries data and big cohort series showing excellent survivorship and clinical outcome comparable to that reported for the most expensive and surgically challenging medial UKR mobile bearing designs. However, whether all polyethylene tibial components (all-poly) provided comparable results to metal-backed modular components during medial fix bearing UKR remains unclear. There have been previous suggestions that all-poly tibia UKR implants might show unacceptable higher rates of early failure due to tibial component early loosening especially in high body max index (BMI) patients. This study aims to find out the short and long-term survival rate of all-poly tibia UKR and its relationship with implant thickness and patient demographics including sex, age, ASA and BMI. Material and Methods. we present the results of a series of 388 medial
Purpose of Study:
BACKGROUND:. Implant wear continues to be a limitation of total knee replacement (TKR). Wear simulator studies are a valuable screening tool in new implant development. The purpose of this study was to determine the ability of micro-CT to prospectively measure wear in TKR implants during a wear simulator trial. METHODS:. Three identical cruciate-retaining,
The outcome and survivorship of osteotomy for medial compartment osteoarthritis are closely correlated to the changes in the weight bearing axis. Questions remain over the optimal correction when undertaking medial unicompartmental knee replacement (UKR). Prospective data was collected on 50 patients (30F:20M) undergoing
Background: The osteolysis in revision total knee arthroplasty was observed. The purpose of this study was to compare the prevalence and characteristics of osteolysis recognized in revision total knee arthroplasties between the failed mobile
Introduction. Wear debris induced osteolysis and loosening continue to be causes of clinical failure in total knee replacement (TKR). Laboratory simulation aims to predict the wear of TKR bearings under specific loading and motion conditions. However, the conditions applied may have significant influence on the study outcomes (1). The aim of this study was to examine the influence of femoral setup and kinematic inputs on the wear of a conventional polyethylene
We report the short term follow up of nineteen consecutive PFC sigma unicompartmental knee replacements carried out in our institution with minimum one year follow up. The PFC Sigma medial unicompartmental knee replacement is a
Purpose. Prospective randomized intervention trial to determine whether patients undergoing rotating platform total knee arthroplasty have better clinical outcomes at two years when compared to patients receiving
Introduction: In vivo fluoroscopic studies have shown considerable differences in kinematics between different designs of knee prostheses and compared to the natural knee. Most noticeably, lift off of the femoral condyles from the tibial insert has been observed in many patients (. Dennis et al, 2003. ). The aim of this study was to simulate lateral femoral condylar lift off in vitro and to compare the wear of
Purpose of Study:
Introduction and Aims A randomised controlled trial (RCT) and a multi-centre unilateral cohort study were performed as part of the stepwise introduction of a new mobile bearing knee. The aim was to ensure that outcome for the new device was at least as good as that for an established
Introduction. Total knee arthroplasty (TKA) is a well-established procedure associated with excellent clinical results. We have previously reported that intraoperative knee kinematics correlate with the clinical outcome in mobile bearing TKA. In addition, the intraoperative knee kinematics pattern does not correlate with the degree of preoperative knee deformity in mobile bearing TKA. However, the relationship among preoperative knee deformity, intraoperative kinematics and clinical outcome in
Introduction: Mobile bearing TKRs may allow some axial rotation and also compensate for a slight tibiofemoral rotational mismatch. This is thought to provide better kinematics and a more natural patellar movement. This theoretical advantage has not been verified in clinical studies for the tibiofemoral kinematics. However, little is known about the patellofemoral kinematics of mobile bearing TKRs. The aim was to compare patellar kinematics among the anatomic knee,
The Profix knee replacement arthroplasty manufactured by Smith and Nephew has been in use for the past five years however there are few published outcome data for this prosthesis. The purpose of this study was to provide clinical outcome data for a cohort of patients with a Profix TKR at a minimum 3 years follow up. There were 65 joint replacements in 58 patients all performed by or under the direct supervision of one of two senior consultant Orthopaedic surgeons. There were 34 right and 31 left knees replaced in 31 male and 27 female patients. Mean age of the patients was 69 years (51–84 years) and mean body mass 89Kg (45–140Kg). The femoral component was uncemented in 49 knees and cemented in 16 knees. The tibial component was cemented in all 65 cases. There were 53 mobile bearing polyethylene inserts and 12
Between 1995 and 1998, eighty revision total knee arthroplasties were done for the primary reason of advanced polyethylene wear. The primary arthroplasties prosthesis that failed included thirty-four mobile bearing knees and forty-six
Introduction. Unidirectional mobile bearing knees (RP) were developed to optimise the tibio-femoral articulation in an effort to enhance function and reduce polyethylene wear. The self aligning bearing should also benefit the patello-femoral joint further improving outcome. This study was designed to assess whether these potential benefits are realised in the clinical setting. Methods. A total of 352 patients undergoing a PS PFC Sigma TKR were randomly allocated to receive either a Mobile Bearing (176 knees) or a
Introduction. Unidirectional mobile bearing knees (RP) were developed to optimise the tibio-femoral articulation in an effort to enhance function and reduce polyethylene wear. The self-aligning bearing should also benefit the patello-femoral joint further improving outcome. This study was designed to assess whether these potential benefits are realised in the clinical setting. Methods. A total of 352 patients undergoing a PS PFC Sigma TKR were randomly allocated to receive either a Mobile Bearing (176 knees) or a
Medial unicompartmental replacement (UKR) has been shown to have superior functional results to total knee replacement (TKR) in appropriately selected patients, and this has been associated with a resurgence of interest in the procedure. This may relate to evidence showing that the kinematic profile of UKR is similar to the normal knee, in comparison to TKR, which has abnormal kinematics. Concerns remain over the survivorship of UKR and work has suggested the anterior cruciate ligament (ACL) may become dysfunctional over time. Cruciate mechanism dysfunction would produce poor kinematics and instability providing a potential mechanism of failure for the UKR. Aim: To test the hypothesis that the sagittal plane kinematics (and cruciate mechanism) of a
Purpose: There are numerous papers from specialist arthroplasty centres outlining results of total knee arthroplasties but little information from outside these major centres. We carried out a review of a
Background. Wear and fatigue damage to polyethylene components remain major factors leading to complications after total knee and unicompartmental arthroplasty. A number of wear simulations have been reported using mechanical test equipment as well as computer models. Computational models of knee wear have generally not replicated experimental wear under diverse conditions. This is partly because of the complexity of quantifying the effect of cross-shear at the articular interface and partly because the results of pin-on-disk experiments cannot be extrapolated to total knee arthroplasty wear. Our premise is that diverse experimental knee wear simulation studies are needed to generate validated computational models. We combined five experimental wear simulation studies to develop and validate a finite-element model that accurately predicted polyethylene wear in high and low crosslinked polyethylene, mobile and
Purpose: As part of the step-wise introduction of a meniscal-bearing total knee replacement (Oxford TMK) we needed to know, before proceeding to longer term studies, whether its early clinical results were at least as good as those of an established
Purpose: In this ongoing trial we are analysing the performance of both a
Recently mobile-bearing total knee arthroplasty (TKA) has become more popular. However, the advantages of mobile bearing (MB) PS TKA still remain unclear especially from a kinematic point of view. The objective of this study was to investigate the difference and advantage in kinematics of mobile baring PS TKA compared with
Introduction and Aims: The study was designed to compare the early results, prospectively, of the fixed-bearing Zimmer NexGen cruciate retaining (CR) and the Zimmer NexGen mobile-bearing knee (MBK) knee arthroplasty. The study was designed to determine whether differences exist in the clinical outcomes between patients receiving different types of bearings. Method: Patients were randomly assigned to receiving either fixed or mobile bearings. Patients were blinded but not assessors to the type of arthroplasty. The study commenced in June 2000. By November 2002, 69 and 70 patients had been recruited into the CR and MBK groups respectively. Consultants were present in 92% of operations and the rest were performed by a senior registrar. The major indication was osteoarthritis (64 CR: 65 MBK). The surgical approach was medial parapatellar in 65 CR and 63 MBK the rest were subvastus, patella resurfacing was not routinely employed. Pre-operative, intra-operative and post-operative data was collated. Results: The body mass index was 32 ± 7 CR and 32 ± 6 MBK. The average age was 67 ± 8 CR and 67 ± 8 MBK. Pain in the contralateral knee was present in 79.7% CR and 74.3% MBK group. Minimum post-operative follow-up was one year. There was no significant difference in the pre-operative and post-operative fixed flexion contracture, 4.3 ± 5.4 to 1.0 ± 2.9 CR and 6.2 ± 6.9 to 0.9 ± 2.8. The mean flexion pre-operatively and post-operatively between the two groups was not significantly different 108 ± 19 to 105 ± 16 CR and 107 ± 15 to 102 ± 13. Patello-femoral joint symptoms diminished from 67% to 12% CR and from 69% to 21% in the MBK group. The dependence on walking aids diminished from 50.7% to 16.7% CR and 51.4% to 26.9% MBK. At one year, nine percent and 21% were dissatisfied in the CR and MBK groups respectively. In the CR group, two revisions had been performed, one for infection and the other for arthrolysis and poly exchange. Two revisions had been carried out in the MBK group, one for extreme ‘clunking’ and the other for arthrolysis with poly exchange. Conclusions: The one-year results suggest that the levels of dissatisfaction and patello-femoral problems are significantly greater in the mobile bearing group as opposed the
Purpose. Total knee arthroplasty (TKA) is the preferred treatment for those with end stage osteoarthritis (OA) and severe functional limitations. With the demographic transition in society, TKA is being offered to a younger patient population. Younger patients are generally more active requiring an increased range of motion, and place greater physiological demands on the prosthesis than typical older patients. The mobile bearing (MB) total knee prosthesis has theoretically been designed to meet these demands. We conducted a meta-analysis and systematic review of randomized controlled trials comparing outcomes of MB and
Clinical experience has shown the needs for high flexion. The aim of this study was to evaluate the clinical and radiological results of a
Summary. We report a large study of 331 patients at two years post operation who were prospectively randomised to receive either a rotating platform or a
Introduction: Total knee arthroplasty (TKA) has become a successful clinical treatment for patients in regard to relief of pain, correction of deformity and restoration of function with promising long term behaviour [Pradhan et al. 2006]. In TKA the generation of polyethylene wear debris is mainly affected by the factors design of the articulating bearing, contact stresses, kinematics, implant material and surface finish [McEwen et al. 2005]. The objective of our study was to evaluate the in vitro wear behaviour of
Introduction There are only a limited number of long term studies of total knee arthroplasty but none with a minimum 15 year survivorship of a modular
Recently mobile-bearing total knee arthroplasty (TKA) has become more popular. However, the advantages of mobile bearing (MB) PS TKA still remain unclear especially from a kinematic point of view. The objective of this study was to investigate the difference and advantage in kinematics of mobile baring PS TKA compared with
Introduction: The aim of this study was to compare the clinical, radiological and functional outcome results of the Scorpio PS TKA prosthesis with either a mobile (MB) or
To evaluate prospectively the mid-term results of the Zimmer Unicondylar Knee arthoplasty (UKA). Between 2005 and 2012, 187 unicompartmental knee arthroplasties (UKA) were performed by a single surgeon using a fixed-bearing prosthesis (Zimmer). 37 cases were excluded as either were lost to follow-up or had less than six months follow-up. The study included 150 UKAs. Deformity, if present, was correctable. Patellofemoral joint (PFJ) disease was not considered as an absolute contraindication. The average patient age at the time of surgery was 66 years (range 42–88 years); 78 of which were male. Mean follow-up time was 3.6 years (range 7–81 months). Mean Body Mass Index (BMI) was 29 (range 21–41). Clinical and conventional radiological evaluations were carried out at six months, one, two and five years postoperatively. 147 cases were medial compartment replacement and three were lateral. 86 patients had grade III OA and 64 had grade IV (Kellgren and Lawrence). 113 patients had an element of PFJ disease. The mean Knee Society knee and function scores had an improvement from 55 and 54 points pre-operatively to 95 and 94 points respectively at time of most recent evaluation. The average flexion improved from 116 degrees pre-operatively to 127 degrees. Two cases were revised, one due to progression of osteoarthritis in the lateral compartment of the knee and the other was due to arthrofibrosis. The Zimmer unicompartmental knee arthroplasty provided excellent pain relief and restoration of function in carefully selected patients. However, long-term studies are necessary to investigate the survival rate for this prothesis.
This randomized controlled double-blind study included to date 14 patients: the gait signatures of four patients with mobile-bearing were compared to the gait signatures of nine patients with fixed-bearing pre-operatively and post-operatively at 6 weeks, 3 months and 6 months. Each participant was asked to perform two walking trials of 30m long at his/her preferred speed and to complete a EQ-5D questionnaire, a WOMAC and Knee Society Score (KSS). Lower limbs rotations were measured by four miniature angular rate sensors mounted respectively, on each shank and thigh. A new method for a portable system for gait analysis has been developed with very encouraging results regarding the objective outcome of total knee arthroplasty using mobile- and fixed-bearings.
Conventional fixed-bearing (FB) knee prostheses have been proved clinically successful. Rotating platform, mobile-bearing (MB) total knee replacements (TKR) have been developed to improve knee kinematics, lower contact stresses on the polyethylene tibial component, minimize constraint, and allow implant self-alignment. The purpose of this study was to characterize and compare the functional outcome of FB- and MB- TKR during gait and deep knee bends, using a motion analysis system. Two groups of five patients with a unilateral FB TKR (PFC) or MB TKR (LCS) underwent a gait analysis study. The normal contralateral limb was used as a control to compare data in the stance phase of gait. Demographic, clinical, and radiographic data were equivalent in the 2 groups. Both MB and FB TKRs gave good functional results in spite of different design rationales. No statistically significant difference was demonstrated between the two groups. However, gait and knee function after TKR was abnormal even though the patients were asymptomatic. A flexional pattern for flex-ion-extension moments at the knee during level walking was present in both types of TKR. Differences in rotational moments between the two groups were observed, with a higher internal rotational moment in the PFC group (PFC, 0.14 Nm/kg; LCS, 0.09 Nm/kg; p=0.094). A stressful weightbearing activity, such as deep knee bends, amplified the functional differences between the different prosthetic designs, indicating that knee kinematics are activity-dependent. Kinetic and kinematic differences noted between the 2 groups reflect different patterns of joint surface motion and loading, with postulated effects on long term failure of the implants through wear, mechanical failure, and loosening. Gait analysis using external skin markers has a limited role in the characterization of the joint surface motion of the prosthetic knee during ambulatory activities because of errors and assumptions inherent in the technique. However, it provides scope for the study of kinetic parameters acting on different knee prostheses during gait.
Mobile-bearing TKRs allow some axial rotation and may provide a more natural patellar movement. The aim was to compare patellar kinematics among the normal knee, fixed-bearing and mobile-bearing TKR. Optical computer navigation (Brainlab) was used to track the position of the femur, tibia and patella in 9 whole lower extremities (5 fresh cadavers) in the natural knee, in the same knee with the trial components of a posterior stabilised fixed-bearing TKR (FB) (Sigma PFC, Depuy) and a posterior stabilised mobile-bearing TKR (MB) (Sigma RP Stabilised). The patellae were not resurfaced. Values: mean+/−one standard deviation. Statistical analysis: two tailed paired Student's T-test.Introduction
Methods
There is conflicting evidence about the merits of using mobile bearings at total knee replacement (TKR), partly because most randomised controlled trials (RCTs) have not been adequately powered. A pragmatic multicentre RCT involving 116 surgeons in 34 UK centres was begun in 1999. Within a partial factorial design, 539 patients were randomly allocated to mobile or fixed bearings. The primary outcome measure was the Oxford Knee Score (OKS); secondary measures included SF-12, EQ-5D, costs, cost-effectiveness and need for further surgery.Introduction
Methods
The choice of the ideal outcome measure to assess total joint replacement remains a complex issue. However, gait analysis provides objective and quantifying evidences of treatment evaluation. Significant methodological advances are currently made in gait analysis laboratories and ambulatory gait devices are now available. The goal of this study was to provide gait parameters as a new objective method to assess total knee arthroplasty outcome between patients with fixed- and mobile-bearing, using an ambulatory device with minimal sensor configuration.
There is conflicting evidence about the merits
of mobile bearings in total knee replacement, partly because most randomised
controlled trials (RCTs) have not been adequately powered. We report
the results of a multicentre RCT of mobile versus fixed
bearings. This was part of the knee arthroplasty trial (KAT), where
539 patients were randomly allocated to mobile or fixed bearings
and analysed on an intention-to-treat basis. The primary outcome measure
was the Oxford Knee Score (OKS) plus secondary measures including
Short Form-12, EuroQol EQ-5D, costs, cost-effectiveness and need
for further surgery. There was no significant difference between the groups pre-operatively:
mean OKS was 17.18 (. sd. 7.60) in the mobile-bearing group
and 16.49 (. sd. 7.40) in the fixed-bearing group. At five
years mean OKS was 33.19 (. sd. 16.68) and 33.65 (. sd. 9.68),
respectively. There was no significant difference between trial
groups in OKS at five years (-1.12 (95% confidence interval -2.77
to 0.52) or any of the other outcome measures. Furthermore, there
was no significant difference in the proportion of patients with
knee-related re-operations or in total costs. In this appropriately powered RCT, over the first five years
after total knee replacement functional outcomes, re-operation rates
and healthcare costs appear to be the same irrespective of whether
a mobile or
Introduction. Backside wear of polyethylene (PE) inlays in fixed-bearing total knee replacement (TKR) generates high number of wear debris, but is poorly studied in modern plants with improved locking mechanisms. Aim of study. Retrieval analysis of PE inlays from contemporary
This study reports updates the previously published two-year clinical, functional, and radiological results of a group of patients who underwent transfibular total ankle arthroplasty (TAA), with follow-up extended to a minimum of five years. We prospectively evaluated 89 patients who underwent transfibular TAA for end-stage osteoarthritis. Patients’ clinical and radiological examinations were collected pre- and postoperatively at six months and then annually for up to five years of follow-up. Three patients were lost at the final follow-up with a total of 86 patients at the final follow-up.Aims
Methods
It has been suggested that mobile-bearing total knee arthroplasty
(TKA) might lead to better outcomes by accommodating some femorotibial
rotational mismatch, thereby reducing contact stresses and polyethylene
wear. The aim of this study was to determine whether there is a
difference between fixed- and mobile-bearing versions of a contemporary
TKA with respect to durability, range of movement (ROM) and function,
ten years postoperatively. A total of 240 patients who were enrolled in this randomized
controlled trial (RCT) underwent a primary cemented TKA with one
of three tibial components (all-polyethylene fixed-bearing, modular
metal-backed fixed-bearing and mobile-bearing). Patients were reviewed
at a median follow-up of ten years (IQR 9.2 to 10.4).Aims
Patients and Methods
Aims. Uncemented mobile bearing designs in medial unicompartmental knee arthroplasty (UKA) have seen an increase over the last decade. However, there are a lack of large-scale studies comparing survivorship of these specific designs to commonly used cemented mobile and
Introduction. This is a multi-centre, prospective, observational study of 503 INFINITY
Aims. The primary objective of this study was to compare migration of the cemented ATTUNE
Introduction. Both mobile
Aims. This is a multicentre, non-inventor, prospective observational study of 503 INFINITY
Introduction. The mobile-bearing (MB) total knee arthroplasty (TKA) design was introduced with the aim of reducing polyethylene wear and component loosening seen in the fixed-bearing (FB) design. A recent joint registry study has revealed increased risk for all-cause revision, but not revision for infection, in MB-TKA. We used the New Zealand Joint Registry (NZJR) to compare all-cause revision rates, and revision rates for aseptic loosening of MB-TKA compared with
Total Knee Arthroplasty (TKA) is an effective surgery performed for knee osteoarthritis. Despite this success up to 20% of patients are less than fully satisfied. Rotating platform (RP) bearings have demonstrated significant reduction in rates of wear in laboratory studies but thus far have failed to demonstrate a clinical difference compared to
Total knee replacement (TKR) design aims to restore normal kinematics with emphasis on flexion range. The survivorship of a TKR is dependent on the kinematics in six-degrees-of-freedom (6-DoF). Stepping up, such as stair ascent is a kinematically demanding activity after TKR. The debate about design choice has not yet been informed by 6-DoF in vivo kinematics. This prospective randomised controlled trial (RCT) compared kneeling kinematics in three TKR designs. 68 participants were randomised to receive either cruciate retaining (CR-FB), rotating platform (CR-RP) or posterior stabilised (PS-FB) prostheses. Image quality was sufficient for 49 of these patients to be included in the final analysis following a minimum 1-year follow-up. Patients completed a step-up task while being imaged using single-plane fluoroscopy. Femoral and tibial computer-aided design (CAD) models for each of the TKR designs were registered to the fluoroscopic images using bespoke software OrthoVis to generate six-degree-of-freedom kinematics. Differences in kinematics between designs were compared as a function of flexion. There were no differences in terminal extension between the groups. The CR-FB was further posterior and the CR-RP was more externally rotated at terminal extension compared to the other designs. Furthermore, the CR-FB designs was more posteriorly positioned at each flexion angle compared to both other designs. Additionally, the CR-RP design had more external femoral rotation throughout flexion when compared with both
Aims. Retrospective review of a consecutive series of 1,168 total ankle replacements (TAR) performed at Wrightington, to analyse modes of failure and clinical outcomes following TAR failure. Methods. All patients undergoing TAR between November 1993 – June 2019 were collated (4–25 year follow-up; mean 13.7 years). 6 implants were used (300 STAR, 100 Buechal Pappas, 509 Mobility, 118 Zenith, 41 Salto and 100 Infinity). 5 surgeons, all trained in TAR, performed the surgery. Modes of failure were collated and clinical and radiological outcomes recorded for the revisional surgery following failure of the TAR. Results. 156 (13.4%) TARs failed (47STAR 15.6%, 16BP 16%, 77Mobility 15.1%, 6Salto 14.6%, 10Zenith 8.5% and 0Infinity 0%). Mean time to failure 5.8 years (0.1- 21.4 years). The 4 most common modes of failure were 44.9% aseptic loosening, 11.5% gutter pain, 10.9% infection and 10.3% recurrent edge loading. 50 underwent conversion to tibiotalocalcaneal (TTC) fusion with nail with 9 (18%) failing to fuse. 31 underwent revision TAR with 2 (6.5%) subsequently failed. 22 underwent ankle fusion with 10 (45%) failing to fuse. 21 underwent polyethylene exchange of which 8 (38%) had further poly failure. 20 (12.8%) were managed conservatively, 2 (1.3%) required below knee amputation and 6 were listed but lost to follow-up. 81 of the 1168 (7%) consecutive cohort were lost to follow-up. Conclusions. 13.4% of the TAR cohort have failed at average follow-up 13.7 years. There was no difference in failure modes across the implant designs. Whilst the
Introduction. In total knee arthroplasty, the alignment of leg depends on the alignment of the component. In unicompartmental knee arthroplasty, it is determined by the thickness of the implant relative to the bone excised mostly. After initial scepticism, UKA is increasingly accepted as a reliable procedure for unicompartmental knee osteoarthritis with the improvements in implant design, surgical technique and appropriate patient selection. Recently, computer assisted UKA is helpful in accuracy and less invasive procedure. But,
Background. Alignment and soft tissue (ligament) balance are two variables that are under the control of a surgeon during replacement arthroplasty of the knee. Mobile bearing medial unicompartmental knee replacements have traditionally advocated sizing the prosthesis based on soft tissue balance while accepting the natural alignment of the knee, while
Purpose. The aim of the present study was to look at survivorship and patient satisfaction of a
Aim. To assess the survivorship of unicompartmental replacements (UKR) revised to UKR. Background: Partial revision of UKR, or revision to a further UKR is a rarely performed procedure with some data from the Australian registry suggesting that results are not good, with early revision being required. Method. All revision procedures from initial UKR are prospectively followed and scored as part of our department's knee database. We analysed the 37 cases in our database that showed revision of UKR to UKR. These included cases in the following categories: a) Mobile bearing revised to mobile bearing (n=8) b) Mobile bearing revised to
Prosthetic Hip dislocations remain one of the most common major complications after total hip arthroplasty procedures, which has led to much debate and refinement geared to the optimization of implant and bearing options, surgical approaches, and technique. The implementation of larger femoral heads has afforded patients a larger excursion distance and primary arc range motion before impingement, leading to lowered risk of hip dislocation. However, studies suggest that while the above remains true, the use of larger heads may contribute to increased volumetric wear, trunnion related corrosion, and an overall higher prevalence of loosening, pain, and patient dissatisfaction, which may require revision hip arthroplasty. More novel designs such as the dual mobility hip have been introduced into the United States to optimize stability and range of motion, while possibly lowering the frictional torque and modes of failure associated with larger
Introduction:. Backside wear has been previously reported through in-vitro and in-vivo to have a significant contribution to the total wear in rotating bearing TKRs. The present study investigated the contribution of backside wear to the total wear in the PFC Sigma rotating platform mobile bearing TKR. In addition, the wear results were compared to the computed wear rates of the PFC Sigma
Purpose: The results of medial unicompartmental knee replacement have been reported as excellent over the intermediate term with both fixed and mobile bearing designs. However not all publications report equal success, with different outcomes also reported between mobile and
Purpose: High contact stresses and wear after total knee replacement (TKR) has been a problem. Mobile bearing TKRs have been advocated as a means to increase load bearing area, reduce contact stresses and minimize wear. The purpose of this study was to compare two, large, consecutive cohorts of TKR patients with greater than 10 years follow-up, one with a
Although good long term results for
Background: In the UK 80% unicompartmental knee replacements(UKRs) and 10% of total knee replacements(TKRs) use mobile bearings. It is suggested that mobile bearings are more physiological and wear less, however it is still unclear whether patients tolerate mobile bearing knee replacements as well. Patients and methods: We report four prospective studies,. Two compared fixed with mobile bearings in TKR and two in UKR. The prostheses involved were fixed and mobile variants of the Rotaglide (TKR), Kinemax (TKR) and Uniglide (UKR). In addition the Oxford and St. George Sled UKRs were compared. All except the Uniglide study were randomized prospective trials (RCTs). 611 patients were involved with a mean age of 68 years. Residual pain following surgery was assessed with either the Oxford Knee Score (OKS) or the WOMAC score. The patients were followed up at one and two years postoperatively by a Research nurse and the findings recorded prospectively on the Bristol Knee database. Results:. Study 1:. Rotaglide. Prospective RCT. 171 patients. Mean pain score (OKS)
Introduction. Mobility at insert-tray articulations in mobile bearing knee implant accommodates lower cross-shear at polyethylene (PE) insert, which in turn reduces wear and delamination as well as decreasing constraint forces at implant-bone interfaces. Though, clinical studies disclosed damage due to wear has occurred at these mobile bearing articulations. The primary goal of this study is to investigate the effect of second articulations bearing mobility and surface friction at insert-tray interfaces to stress states at tibial post during deep flexion motion. Method & Analysis. Figure 1 shows the 3-D computational aided drawing model and finite element model of implant used in this study. LS-DYNA software was employed to develop the dynamic model. Four conditions of models were tested including
Introduction: Literature fails clearly to indicate an advantage of a mobile bearing over the
Introduction. Previous fluoroscopy studies have been conducted on numerous primary-type TKA, but minimal in vivo data has been documented for subjects implanted with revision TKA. If a subject requires a revision TKA, most often the ligament structures at the knee are compromised and stability of the joint is of great concern. In this present study, subjects implanted with a fixed or mobile bearing TC3 TKA are analyzed to determine if either provides the patient with a significant kinematic advantage. Methods. Ten subjects are analyzed implanted with
Introduction. Kneeling ability is better in unicompartmental than total knee arthroplasty. There is also an impression that mobile bearing knees achieve better functional outcome than their
Introduction: There is an impression among Orthopaedic surgeons that mobile bearing knee replacement has a better functional outcome than
Partial knee arthroplasty is making a resurgence as many patients and surgeons are realising that there are good options for preserving normally functioning knee tissues when facing end-stage knee OA without having to automatically proceed to TKA. What are potential advantages of this type of reasoning and could “less be more”? Limited comparative data exists comparing the functional results of partial and total knee replacement surgery. This study will report on patient satisfaction and residual symptoms following TKR,
Introduction: Uni-compartmental Knee Replacement (UKR) has now become an accepted and widely used treatment for uni-compartmental arthritis. Our unit has performed over 1000 UKRs in the past 22 years. The optimal mechanical design of the implant has yet to be determined. Method: A prospective trial was commenced in 1999 to compare the short-term results of a
Knee flexion is often decreased in severe arthritis causing pain, and functional limitations in lifestyles and occupations. Newer knee replacement designs offer the possibility of greater knee motion. The objective of our study was to compare the clinical outcomes, in particular the range of motion, in patients treated with a total knee arthroplasty using either a standard posterior stabilized knee prosthesis or a high flexion posterior stabilized knee prosthesis, with regard to return to function within 1 year of surgery. This was a prospective randomized single blinded study. Forty patients were randomly assigned to receive either a standard
The aim of this prospective cohort study is to compare the early results in a single surgeon series of the mobile and
Introduction: There is an impression among Orthopaedic surgeons that mobile bearing knee replacement has a better functional outcome than
Background: Although many knee surgeons routinely perform unicompartmental replacement (UKR) for medial compartment arthrosis there is still reluctance to perform lateral UKR’s as they are generally thought to be less satisfactory. The purpose of the present study was to prospectively compare the outcome of lateral UKR’s with medial UKR’s using the AMC Uniglide knee implant. Methods: Between 2002 and 2005, 29 lateral
Aim: This study aims to establish whether or not mobile bearing TKR delivers the often stated benefits improved function and range of motion when compared to its
Introduction. Special high-flexion prosthetic designs show a small increase in postoperative flexion compared to standard designs and some papers show increased anterior knee pain with these prosthesis. However, no randomised controlled trails have been published which investigate difference in postoperative complaints of anterior knee pain. To assess difference in passive and active postoperative flexion and anterior knee pain we performed a randomized clinical trial including the two extremes of knee arthroplasty designs, being a high flex posterior stabilized rotating platform prosthesis versus a traditional cruciate retaining
Background. Previous in vivo fluoroscopic studies have documented that subjects having a PS TKA experience a more posterior condylar contact position at full extension, a high incidence of reverse axial rotation and mid flexion instability. More recently, a PS TKA was designed with a Gradually Reducing Radius (Gradius) curved condylar geometry to offer patients greater mid flexion stability while reducing the incidence of reverse axial rotation and maintaining posterior condylar rollback. Therefore, the objective of this study was to assess the in vivo kinematics for subjects implanted with a Gradius curved condylar geometry to determine if these subjects experience an advantage over previously designed TKA. Methods. In vivo kinematics for 30 clinically successful patients all having a Gradius designed PS
Total knee arthroplasty has been demonstrated to provide durable results with excellent pain relief and improvement in function. Our institution has studied and published the longest follow-up of mobile
Introduction: Mobile bearing total knee arthroplasty (TKA) has been developed to theoretically provide better, more physiological function of the knee and produce less PE wear. The theoretical superiority of mobile bearing TKAs over
Physiological kinematics is very difficult to restore after total knee arthroplasty (TKA). A new model of medial stabilized (MS) TKA prosthesis has a high spherical congruence of the internal compartment, which guarantees anteroposterior (AP) stability associated with a flat surface of the insert in the lateral compartment, that allows a greater AP translation of the external condyle during knee flexion. The aim of our study is to evaluate, by dynamic radiostereometric analysis (RSA), the knee in vivo kinematics after the implantation of a MS prosthesis during sit to stand and lunge movements. To describe the in vivo kinematics of the knee after MS
Reduction of ultra high molecular weight polyethylene (UHMWPE) surface wear in total knee replacements (TKR) may delay the onset of osteolysis and loosening of components. This study examined the wear of
Variation in soft tissue constraints influence the kinematics and wear of total knee replacements (TKRs). The aim of this study was to experimentally investigate the effect of variation in the soft tissue constraints on the output kinematics of a
As allergic reactions to implant wear are gaining more attention [4], the incorporation of ceramic materials to device design appears to be a promising development. In particular, ceramic femoral components of total knee replacements have been designed to produce less wear under standard [1] and adverse [5] implant conditions. Whereas the wear reduction effect of ceramics is generally accepted for hip implants, the corresponding effect for knee implants is not proven. Ezzet et al. reported a wear reduction of 42% for standard wear conditions [2] and of 55% for adverse wear conditions [3] when compared to a geometrically identical CoCr femoral component. In contrast to these findings, an analysis of the EndoLab® database has indicated wear rates of ceramic knee implants that are comparable to traditional low wear material couplings (Figure 1), and are within the range of clinically established devices. The purpose of this study was to directly compare two TKR designs, one
Objectives. Initial stability of tibial trays is crucial for long-term success of total knee arthroplasty (TKA) in both primary and revision settings. Rotating platform (RP) designs reduce torque transfer at the tibiofemoral interface. We asked if this reduced torque transfer in RP designs resulted in subsequently reduced micromotion at the cemented fixation interface between the prosthesis component and the adjacent bone. Methods. Composite tibias were implanted with fixed and RP primary and revision tibial trays and biomechanically tested under up to 2.5 kN of axial compression and 10° of external femoral component rotation. Relative micromotion between the implanted tibial tray and the neighbouring bone was quantified using high-precision digital image correlation techniques. Results. Rotational malalignment between femoral and tibial components generated 40% less overall tibial tray micromotion in RP designs than in standard
Introduction: Mobile bearing TKA systems have drawn great attention as an alternative solution for the limitations of
The long-term survival of total knee arthroplasty (TKA) has been well established; however, functional outcome remains inconsistent. More normal postoperative TKA kinematics have been shown to produce better knee function. Improved kinematics can be obtained by using implants with optimised surface geometry. Hence a TKA with an appropriate surface geometryis likely to provide superior long-term functional outcome. The Advance-Medial Pivot TKA (Wright Medical) is a
We prospectively reviewed a consecutive series of 101 patients with mobile bearing total knee replacement (TKR) and 72 patients with the
Introduction and Aims: Movements between the poly-ethylene insert and the metal tibial tray in modular
Introduction: Mobile bearing total knee arthroplasty (TKA) has been developed to theoretically provide a better, more physiological function of the knee and produce less polyethylene (PE) wear. The theoretical superiority of mobile bearing TKA’s over
The objective of this present study is to conduct a comparative analysis of the kinematic data derived for all subjects having a TKA who were analysed over the past eight years at our laboratory. Femorotibial contact positions for 705 subjects having either a
Introduction: This study evaluated the creep and true wear in 55 medial and in 35 lateral