Current analysis of unicondylar knee replacements (UKR) by national registries is based on the pooled results of medial and lateral implants. Using data from the National Joint Registry for England and Wales (NJR) we aimed to determine the proportion of lateral UKR implanted, their survival and reason for failure in comparison to medial UKR. By combining information on the side of operation with component details held on the NJR we were able to determine implant laterality (medial vs. lateral) for 32,847 of the 35,624 (92%) UKR registered before December 2010. Kaplan Meier plots, Life tables and Cox' proportion hazards were used to compare the risk of failure for lateral and medial UKRs after adjustment for patient and implant covariates.Background
Methods
Both surgeon and hospital volume influence patient outcomes following revision knee arthroplasty. To audit all centres performing revision knee procedures in England and Wales over a 2-year period. All centres were audited against two pre-defined standards linked to hospital volume Operative volume should be greater than 10 revisions per year; More than 2.5 revisions should be performed for every 100 primary arthroplasties implanted.Background
Purpose
High flexion knee arthroplasties have been designed to allow up to 155 degrees flexion and enable high flexion activities such as kneeling and squatting. To date randomised controlled trials have shown no difference in range of movement (ROM) between high flexion and standard designs. The aim of this study was to determine if there is a difference in functional outcome and ROM between the standard and high flexion design of the PFC Sigma TKA system.Introduction
Objectives
Following in-depth analysis of the market leading brand combinations in which we identified implant influences on risk of revision, we compared revision in patients implanted with different categories of hip replacement in order to find implant with the lowest revision risk, once known flawed options were removed. All patients with osteoarthritis who underwent a hip replacement (2003–2010) using an Exeter-Contemporary (cemented), Corail-Pinnacle (cementless), Exeter-Trident (Hybrid) or a Birmingham Hip resurfacing (BHR) were initially included within the analysis. Operations involving factors that were significant predictors of revision were excluded. Cox proportional hazard models were then used to assess the relative risk of revision for a category of implant (compared with cemented), after adjustment for patient covariates.Introduction
Methods
To determine how patient characteristics; health status and pre-operative knee function effect patient reported satisfaction and operative success following total knee replacement (TKR). We hypothesised that a number of patient factors would influence the reported levels of symptomatic improvement (success) and satisfaction and that these two outcomes would represent different aspects of the patient's perception of outcome. Retrospective cohort analysis of patient reported outcome measures (PROMs) and National Joint Registry (NJR) data. Complete patient data was available for 9,874 TKRs performed for osteoarthritis between 1/8/08 and 31/12/10. The relationship of the background factors to patient perceived satisfaction and success was investigated using ordinal logistic regression and structural equation modelling (SEM).Purpose
Design
The most appropriate form of chemical thromboprophylaxis following knee replacement is a contentious issue. Most national guidelines recommend the use of low molecular weight Heparin (LMWH) whilst opposing the use of aspirin. We compared thromboembolic events, major haemorrhage and death after knee replacement in patients receiving either aspirin or LMWH. Data from the National Joint Registry for England and Wales was linked to an administrative database of hospital admissions in the English National Health Service. A total of 156 798 patients undergoing knee replacement between April 2003 and September 2008 were included and followed up for 90 days. Multivariable risk modelling was used to estimate odds ratios adjusted for baseline risk factors (AOR). An AOR < 1 indicates that risk rates are lower with LMWH than with aspirin.Background
Methods
To examine how patients viewed the outcome of their joint replacement at least one year post surgery. Emphasis was placed on investigating the relative influence of ongoing pain and functional limitation on patient satisfaction. Questionnaire based assessment of the Oxford Knee Score (OKS), patient satisfaction, and need for reoperation in a group of 10,000 patients who had undergone primary unilateral knee replacement between April and December 2003. Questionnaires were linked to the NJR database to provide data on background demographics, clinical parameters and intraoperative surgical information for each patient. Data was analysed to investigate the relationship between the OKS, satisfaction rate and the background factors. Multivariable logistic regression was performed to establish which factors influenced patient satisfaction.Purpose
Method
We have carried out a 15 year survival analysis of a prospective, randomised trial comparing cemented with cementless fixation of press-fit condylar primary total knee replacements. A consecutive series of 501 PFC knee replacements received either cemented (219 patients, 277 implants) or cementless (177 patients, 224 implants) fixation. No patients were lost to follow up. Revision was defined as further surgery, irrespective of indication, that involved replacement of any of the three originally inserted components (Femur, Tibia, Patella).Introduction
Methods
The purpose of this study was to establish whether men and women with a fragility hip fracture were equally investigated and treated for osteoporosis. A retrospective review was carried out including 91 patients (48 females, 43 males) who were admitted with a fragility hip fracture between March 2003 and April 2004. Data about age, sex, investigations and medication were collected from the case notes, GP surgeries and the bone densitometry database. Investigations and treatment were compared with current guideline recommendations (SIGN 2003, NICE 2005). Data were analysed using SPSS Version 13.0.Introduction
Methods
This study evaluates the effect of lower limb post-operative mechanical axis on the long term risk of revision surgery following primary total knee arthroplasty (TKA). The study is relevant because many recent clinical trials have evaluated the optimal surgical technique for accurately aligning components in TKA, despite little evidence that alignment may effect the long-term clinical outcome. The data used in this study was collected prospectively as part of a randomized control trial comparing the long term survival of cemented versus uncemented TKA. The trial included 501 press-fit condylar posterior cruciate ligament-retaining prostheses performed by the senior author (PJG) or under his direct supervision. The post-operative mechanical axis alignment of the lower limb was measured following TKA using standard AP weight-bearing long leg alignment radiographs. A comparison was made between a well-aligned group with a mechanical axis alignment within 3° of neutral; and a poorly-aligned group whose mechanical axis alignment deviated greater than 3° from neutral. Survival analysis used revision surgery, with exchange of any of the three originally inserted components (femoral, tibial, polyethylene insert), as the endpoint. There was no loss to follow-up in this study. The minimum follow-up of TKAs in this study was 5.8 years. In the population of TKAs that were followed up at 10 years, 6% (17/270) required revision surgery. There was a significant difference in the rate of revision surgery between the well-aligned group 5% (11/227) and the poorly-aligned group 14% (6/43 p<
0.05) This study shows that post-operative lower limb mechanical axis alignment is an important determinant of the need for revision surgery at 10 years. Surgeons performing TKA should pay particular attention to the placement of the tibial and femoral components, so that a mechanical axis within 3° of neutral is achieved.
Before surgery patients were asked to complete a psychological questionnaire consisting of Revised Illness Perception Questionnaire (IPQ-r), Hospital Anxiety and Depression Scale (HADS) and Recovery Locus of Control (RLOC). Knee function was assessed preoperatively, at six weeks and one year using Oxford Knee Score (OKS) and range of motion (ROM).
The psychological factors Consequences, Illness Coherence, Emotional Representation and HADS Anxiety showed a statistically significant correlation with the OKS at six weeks, the factors Consequences and HADS Anxiety and HADS Depression with the OKS at one year. We found no correlation with range of motion at six weeks, but ROM at one year was statistically significantly correlated with the factors Consequences and HADS Depression. This indicates that patients who believed that their illness had less impact on their personal lives and patients with lower scores on the anxiety and depression scale showed a lower OKS and higher ROM at one year, indicating a better functional outcome. Hierarchical regression analysis showed that, after controlling for demographics and baseline scores, the factor consequences explained 7% of the variance in ROM at one year. HADS Anxiety and Depression had a significant impact on OKS and accounted for 13.7% of the variance of OKS at one year.
We report the 15 year follow-up of displaced intra-articular calcaneal fractures from a randomised controlled trial of conservative versus operative treatment. Of the initial study, 46 patients (82%) were still alive and 26 patients (57%) agreed to review. The clinical outcomes were not different between operative versus conservative treatment. American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale: p = 0.11; Foot Function Index (FFI): p = 0.66; and calcaneal fracture score: p = 0.41. The radiological outcomes also were not different between both groups. Böhler’s angle: p = 0.07; height of calcaneum: p = 0.57; and grade of osteoarthritis of the subtalar joint: p = 0.54. There was no correlation between Böhler’s angle and the outcome measures in either group. The results of this 15 year follow-up of displaced intra-articular calcaneal fracture randomised controlled trial demonstrate similar findings to those at one year follow-up.
We report the results of a prospective randomised controlled clinical trial assessing the radiosterophotogrametric analysis (RSA), clinical and radiological performance of a metal backed and an all-polyethylene tibial cruciate retaining, condylar design, PFC-TKA up to twenty four months. 65 patients were recruited, of which 41 patients were randomised. There were 20 metal backed and 21 all-polyethylene. None were lost to follow-up. There were no significant inter-group demographic differences. We found a significant increase in SF-12 and Oxford knee scores after surgery in both groups. No significant difference was found between the groups in the RSA, SF-12, Oxford Knee score, radiological alignment and range of movement at 6, 12 or 24 months. At 2 years one metal backed implant showed translational migration >
1mm. No all polyethylene implant migrated >
1mm. Further analysis identified possible progressive subsidence of the metal backed implants compared to all-polyethylene implants, although the magnitude of this difference was very small. We conclude that in the uncomplicated primary total knee arthroplasty, all polyethylene PFC-_ tibial prostheses had equivalent performance to the metal backed counterpart, using RSA as the primary assessment instrument at 24 months. We found no differences between the two designs as assessed by the secondary instruments: SF-12, Oxford knee score, alignment and range of movement at 24 months. Should half of all primary total knee replacements performed in the UK receive an all-polyethylene tibial implant, the estimated annual cost saving would be 21 million pounds per annum.
To identify mechanisms of failure in plate and nail fixation in proximal humerus fractures. 5% of the proximal humerus fractures need surgical fixation, which is carried out, principally, by open reduction and internal fixation or closed reduction and intramedullary nailing. Fixation failure remains a problem. This study answers the mode of failure of these implants regardless of the fracture personality. In-vitro testing of proximal humerus fixation devices was undertaken in 30 simulated osteoporotic bone models. Fracture-line was created at the surgical neck of humerus in all samples and fixed with five fixation devices; three plating and two nailing devices. The samples were subjected to failure under compression and torque. Failure was achieved in all models. Three failure patterns were observed in torque testing:
The two conventional plates Cloverleaf and T-plate behaved similarly, failing due to screw pull-out from both the proximal and distal fragment with a deformed plate. The PHILOS plate failed by avulsion of a wedge just distal to the fracture site with screws remaining embedded in the bone. Both the nailing systems, Polaris and European humeral nail, failed by a spiral fracture starting at the distal locking screw. In compression testing the modes of failure were: The Clover-leaf and T-plate failed by plastic deformation of plate, backing out of the screw in the proximal fragment followed by fracture of the distal fragment. The PHILOS failed by plastic deformation of plate and fracture of the distal fragment distal to the last locking screws. In both the nails, the proximal fragment screws failed. The failure mode is dependent on implant properties as well, independent of the fracture personality. It is important to recognise the potential points of failure (proximal or distal fragment) when making the choice of implant to avoid fixation failure.
The aim of this study was to determine whether there is a difference in the functional outcome between fixed and mobile bearings in total knee arthroplasty. 120 patients were randomized (computer generated) to receive either a fixed or mobile bearing P.F.C. Sigma total knee replacement. 96 patients were needed to detect a 20° difference in range of motion (ROM) with a significance level of 0.05 and a test power of 0.97. Oxford knee score (OKS) and ROM were assessed independently before and one year after surgery. Mean ROM and Oxford knee score before and at one year after surgery for both groups are shown as preliminary results for 70 patients (follow-up expected to be completed by March 2006): There is no statistically significant difference in the mean ROM at one year and in change in ROM between the two groups (p=0.53 and p=0.21 respectively). The findings were similar for Oxford Knee Score at one year and change in Oxford Knee Score (p=0.45 and p=0.82). There was no early aseptic loosening in either group. The one year results suggest that there is no significant difference in functional outcome measured as ROM and Oxford Knee Score between the two types of bearing. Further follow-up will be carried out to detect any differences in the long term outcome.
A trend towards lesser degrees of improvement in the outcome scores was noted with increasing age. The degree of improvement in the outcome scores was not affected by sex, limb dominance or fracture type (Neer’s classification).
Pain relief was obtained in 84/193 cases (43.5%). In 122 cases where the aim was to avoid surgery, this was achieved in 52 cases (42.6%). Success rate decreased with increasing severity of disease (Fisher’s Exact test; p<
0.01). Only 25/122 cases with PFJ involvement had pain relief (21%), compared to 59/71 cases without PFJ involvement (83%), (Chi squared test; χ 2(1)=71.57, p<
0.01). Younger age (<
60 years) is a poor prognostic factor (Chi squared test; χ2(1)= 5.86, p=0.02).
The National Institute for Clinical Excellence (NICE), in its “Guidance on the Selection of Prostheses for Primary Total Hip Replacement”, states that a revision rate of 10% or less at ten years should be regarded as the “benchmark” in the selection of prostheses for primary Total Hip Replacement (THR). This paper presents the results of such a study for primary Charnley THR. Methods: All patients undergoing primary Charnley THR during 1990 were prospectively registered with the Trent Regional Arthroplasty Study (TRAS). During 1990, 1198 Charnley THRs were performed on 1152 patients, under the care of 56 consultants, in 18 National Health Service and 6 private hospitals. The cohort contains 39.0% male and 61.0% female patients, with an average age at operation of 69.1years (21–103 years), 19.1% being less than 60 years. At 10 years all surviving patients at 5 years were registered with the ONS to ascertain living patients. These patients were contacted by letter to determine whether or not their THR had been revised. The status of the THR, for non-responding patients, was determined by contacting the patient’s GP through the Contractor Services Agency (CSA). The endpoint was defined as revision surgery to replace an original implant component. Results: At 10 years, the recipients of 438 THRs had died. The recipients of 89 THRs did not respond to the questionnaire at ten years. Implant status at ten years, in living patients was known for 671 of 760 (88.3%) THRs. The ten-year crude revision rate was 44 out of 1198 (3.7%) and cumulative survival rate was 95.5% (95% CI, 93.6% – 96.9%). Conclusion: This is the first study to assess the survivorship at 10 years for primary Charnley THRs performed in the ‘general setting’ of the NHS as opposed to specialist centres and shows a result well within the NICE benchmark.
The Department of Health and the Public Health Laboratory Service established the Nosocomial Infection National Surveillance Scheme (NINSS) in response to the need to standardise the collection of information about infections acquired in hospital. This would provide national data that could be used as a ‘benchmark’ by hospitals to measure their own performance. The definition of superficial incisional infection (skin and subcutaneous tissue), set by Centers of Disease Control (CDC), should meet at least one of the following criteria: I: Purulent drainage from the superficial incision. II: The superficial incision yields organisms from the culture of aseptically aspirated fluid or tissue, or from a swab, and pus cells are present. III: At least two of the following symptoms and signs of inflammation: pain or tenderness, localized swelling, redness or heat, and a. the superficial incision is deliberately opened by a surgeon to manage the infection, unless the incision is culture-negative or b. clinician’s diagnosis of superficial incisional infection. This study assessed the interobserver reliability of the superficial incisional infection criteria, set by the CDC, in current practice. The incisional site of 50 consecutive patients, who underwent elective primary joint arthroplasty (Hips &
Knees), were evaluated independently by four observers. The most significant results of the study I: All four observers achieved absolute agreement (kappa=1) for Purulent wound discharge and clinical diagnosis of wound infection. II: The four observers obtained good agreement for pain criteria (kappa=0.76, III: There was significant disagreement (fair to poor) between all four observers for the following criteria: Localized swelling (kappa=0.34), Redness (kappa=0.33) and tenderness (kappa = 0.05). This is the first study to assess the reliability of the criteria, as set by the CDC and recommended by NINSS, for the diagnosis of superficial incisional infection and shows the Criterion III is not reliable and we recommend it should be revised. Failure to do so could lead to inaccurate statistics regarding hospital wound infection and detrimental effect on hospital trusts in the setting of league table.
Cementless fixation for total knee arthroplasty (TKA) has been proposed as an alternative to cemented for several reasons, of which the most important is the possibility of increased survival. The purpose of this study was to compare the ten-year survival of TKA in a unique prospective randomised trial of cemented versus cementless fixation. A consecutive series of patients was randomised to undergo either cemented or cementless Press-Fit Condylar (PFC®) TKA. There were 219 patients (277 TKA) in the cemented group and 177 (224 TKA) in the cementless group. There were no significant differences in age, gender or diagnosis between the two groups. A single surgeon (PJG) performed or directly supervised all operations. The prosthesis used in all cases was the posterior-cruciate-retaining PFC® knee replacement system. Independent clinical review was performed at six months, annually until five years, and finally at ten years after surgery. Using revision surgery as the end-point, logrank analysis was used to compare the ten-year survival of the two groups. The mean interval of follow-up was 6.3 years (range, 2.0–11.7). At the last review, 104 patients (138 TKA) had died, without need for revision. All patients were traced and there was no loss to follow-up. In the cemented group, seven arthroplasties were revised; five for infection and two for exchange of polyethylene inserts. Ten-year survival was 96.5% (95% CI, 90.9–98.7%). In the cementless group, six arthroplasties were revised; three for aseptic loosening, one for infection, one for instability and one resizing for anterior knee pain. The ten-year survival was 96.6% (95% CI, 89.6–98.9%). There was no significant difference in the survival of the two groups. The long-term survival of cementless PFC® TKA is not significantly different from their cemented counterparts. The use of less expensive cemented implants, therefore, can make a significant impact on health resource planning.
To establish whether there were features present on the initial post-operative radiographs of total hip replacements (THR) predictive of aseptic loosening. Our data was derived from the Trent Regional Arthroplasty Study (TRAS) which is the only hip register of its kind in the country. The TRAS commenced in 1990 and has recorded clinical and operative details of all THRs in the region. Our current study was concerned with a cohort of grossly loose THRs, identified from the five-year follow up of those patients who had undergone THR in 1990. Our cohort are those which failed specifically due to aseptic loosening and comprises those revised or listed for revision as well as a number of previously undiagnosed cases. The post-operative radiographs were analysed, recording the following: (1) number, width and location (Gruen zone) of radiolucencies at both cement-bone and cement-prosthesis interfaces; (2) presence of stem-cortex contact; (3) width of the cement mantle in each Gruen zone; and (4) Barrack cementation grade. Occasionally, if the initial post-operative radiograph was of poor quality, then further information was gained from the next available ones (usually at six weeks) to improve accuracy. Comparisons were made with 60 control hips randomly generated from the same 1990 cohort but which had not failed. Chi-squared tests were used to test the probability of obtaining the observed data by chance and odds ratios were calculated to describe relative risk of failure for different risk factors. Hips with inadequate cementation grades (C and D) had a 9.5 times greater risk of failure compared to those with adequate cementation grades (A and B) [p<
0.0001]. We have demonstrated that the grade of cementation has a major effect on the probability of failure. This emphasises the importance of good cementing, which is particularly relevant in this era of clinical governance where there is greater accountability on the surgeon for adequate performance.
Cementation is an important part of arthroplasty operations. Recent publication of results of Charnley total hip replacement found a rate of early aseptic loosening of 2.3% at 5 years following surgery across a NHS region. There are possibly many reasons for early loosening but precise reasons are still not fully understood, however, it is felt that cementation technique is very important. There seems to be a number of factors involved such as cement mixing techniques and conditions, physical properties of the cement, cementation and surgical techniques, bone-cement interface as well as bone- prosthesis interface. The purpose of this study was to evaluate the effectiveness of the clinical environment in producing bone cement of predictable mechanical and physical properties, and how those properties compare with published data. The investigation compared samples of bone cement, taken from material prepared and used in surgery with cement samples prepared under controlled laboratory conditions and in accordance with ISO materials testing standards. During 2000–01, 10 total hip replacements were selected for study. All operations involved the use of CMW1 (DePuy) radio-opaque cement, which was mixed using the Vacumix system. In this cohort, all femoral cementations were performed using an 80g cement mix. After careful preparation of the femoral canal, the scrub nurse mixed the cement in accordance with the manufacturer’s instructions. The cement was introduced into the femoral canal, via a nozzle, using the cementation gun and a pressurizer. Following introduction of cement into the canal, the nozzle and cement contained within, was broken off the gun distal to the pressurizer. Once cured, the cement samples were removed from the nozzle, sectioned, and mechanically tested. Due to this novel sample preparation procedure, the tested cement was expected to exhibit mechanical and physical properties characteristic of the cement present in the femoral canal. Samples of CMW1 (Vacumixed) of similar mass and aspect ratio were produced within the laboratory, in accordance with the manufacturers mixing instructions. PMMA bone cement is a brittle, glassy polymer that is susceptible to stress raisers, such as pores, which can reduce the load carrying ability, which The surgical samples were found to be very consistent in compressive strength (121 ± 6 MPa), density (1.20 ± 0.02 gcm−3) and hardness (23.2 ± 1.6 VHN) and closely matched the mechanical properties of the cement mixed in the laboratory. This study suggests that for the studied cement and mixing regime, the clinical environment is capable of producing a well-controlled cement product that has reproducible and predictable mechanical properties. Further, the novel sample preparation procedure used suggests that the cement within the femoral cavity should demonstrate equally predictable, mechanical and physical properties.