We investigated whether blood metal ions could effectively identify bilateral metal-on-metal hip patients at risk of adverse reactions to metal debris (ARMD). This single-centre, prospective study involved 235 patients (185 bilateral Birmingham Hip Resurfacings (BHRs) and 50 bilateral Corail-Pinnacles) undergoing whole blood metal ion sampling (mean time=6.8 years from latest implant to sampling). Patients were divided into ARMD (revised or ARMD on imaging; n=40) and non-ARMD groups (n=195). Metal ion parameters (cobalt; chromium; maximum cobalt or chromium; cobalt-chromium ratio) were compared between groups. Optimal metal ion thresholds for identifying ARMD patients were determined using receiver operating characteristic (ROC) analysis, which compares the performance of different tests using the area under the curve (AUC) (higher AUC=more discriminatory).Introduction
Patients and methods
Blood metal ion sampling can help detect poorly functioning metal-on-metal hip arthroplasties (MoMHA's) requiring revision. Little is known about the variation in these levels following bearing exchange. This study aimed to determine the changes that occur in blood and urine metal ion concentrations following MoMHA revision. A single-centre prospective cohort study was undertaken between 2005 and 2012 of patients with failing large-diameter MoMHA's and high blood metal ions requiring revision to non-metal-on-metal articulations. All patients had normal renal function. Whole blood and urine were collected for metal ion analysis preoperatively and regularly following revision. Twenty-three MoMHAs (21 hip resurfacings and 2 total hip arthroplasties; mean age 56.0 years and 65% female) were revised at a mean time of 7.9 years (range 2.0–14.5 years) from primary surgery. All revisions were performed by the senior author using primary total hip implants (12 ceramic-on-polyethylene bearings, 10 oxinium-on-polyethylene bearings, and 1 metal-on-polyethylene bearing implanted). Mean (range) metal ion concentrations pre-revision were: blood cobalt 13.9µg/l (1.32–74.7µg/l), blood chromium 8.9µg/l (1.29–57.3µg/l), urine cobalt 104.6µg/24 hours (4.35–747.3µg/24 hours), urine chromium 33.2µg/24 hours (4.39–235.4µg/24 hours). After revision the mean metal ion concentrations (percentage of pre-revision values) were: blood cobalt at 2 days=10.7µg/l (77%), 6 days=7.7µg/l (55%), 2 months=3.4µg/l (24%), 1 year=1.0µg/l (7%), 2 years=0.42µg/l (3%); blood chromium at 2 days=8.7µg/l (98%), 6 days=5.5µg/l (62%), 2 months=2.2µg/l (25%), 1 year=1.5µg/l (16%), 2 years=0.97µg/l (11%); urine cobalt at 2 days=31.9µg/24 hours (30%), 6 days=21.5µg/24 hours (21%), 2 months=6.1µg/24 hours (6%), 1 year=0.99µg/24 hours (1%), 2 years=0.61µg/24 hours (1%); urine chromium at 2 days=34.4µg/24 hours (103%), 6 days=15.8µg/24 hours (48%), 2 months=9.3µg/24 hours (28%), 1 year=2.8µg/24 hours (8%), 2 years=1.9µg/24 hours (6%). Following MoM revision cobalt levels decline rapidly in an exponential pattern with a single rate of decay through the 2 year period, reaching reference levels within the first year. Chromium follows a similar pattern but starts lower and takes longer. Renal response to cobalt returns to reference level within days of revision.
High short-term failure rates have been observed with a number of metal-on-metal (MoM) hip designs. Most patients require follow-up with blood metal ions, whichprovide a surrogate marker of in-vivo bearing wear. Given these results are used in clinical decision making it is important values obtained within and between laboratories are reproducible. To assess the intra-laboratory and inter-laboratory variability of blood metal ion concentrations analysed by four accredited laboratories. Whole blood was taken from two participants in this prospective study. The study specimen was obtained from a 42 year-old female with ceramic-on-ceramic hip arthroplasty failure resulting in unintended metal-on-ceramic wear and excessively high systemic metal ion levels. The control specimen was from a 52 year-old healthy male with no metal exposure. The two specimens were serially diluted to produce a total of 25 samples with different metal ion concentrations in two different anticoagulants each. Thus 50 samples were sent blinded in duplicate (total 100) to four accredited laboratories (A, B, C, D) to independently analyse blood metal ion concentrations. Ten commercially available reference specimens spiked with different amounts of metal ions were also obtained with known blood metal ion concentrations (range for cobalt 0.15µg/l-11.30µg/l and chromium 0.80µg/l to 37.00µg/l) and analysed by the four laboratories. The intra-laboratory coefficients of variation for repeat analysis of identical patient specimens were 7.32% (laboratory A), 4.64% (B), 7.50% (C), and 20.0% (D). The inter-laboratory variability for the analysis of all 25 samples was substantial. For the unmixed study specimen the laboratory results ranged from a cobalt of 263.7µg/l (D) to 525.1µg/l (D) and a chromium of 13.3µg/l (D) to 36.9µg/l (A). For the unmixed control specimen the laboratory results ranged from a cobalt of 0.13µg/l (B) to 0.77µg/l (D) and a chromium of 0.13µg/l (D) to 7.1µg/l (A). For one of the mixed specimens the laboratory results ranged from a cobalt of 12.50µg/l (A) to 20.47µg/l (D) and a chromium of 0.73µg/l (D) to 5.60µg/l (A). Similar inter-laboratory variation was observed for the other mixed samples. The true mean (standard deviation) of the 10 commercial samples was 4.48µg/l (4.20) for cobalt and 8.97µg/l (10.98) for chromium. This was similar to the values obtained by all four laboratories: mean (standard deviation) cobalt ranged from 3.54µg/l (3.17) in laboratory A to 4.35µg/l (4.13) in laboratory D, and chromium ranged from 7.76µg/l (9.50) in laboratory B to 9.55µg/l (9.16) in laboratory A. When testing patient samples, large variations existed both between and within four laboratories accredited to perform analysis of blood metal ion concentrations. However, this was not the case when assessing commercially spiked samples which are regularly used to validate laboratory testing. This is of great clinical concern and could lead clinicians to either recommend unnecessary revision or delay surgery, with both having the potential to adversely affect patient outcomes. It is recommended that laboratories use patient samples to assess the accuracy and reproducibility of the analyses performed. This may also assist in explaining the variations observed in this study.
Little is known about variations in blood metal ions following bearing exchange for poorly functioning metal-on-metal hip replacements (MoMHRs). This study aimed to determine the changes that occur in blood and urine metal ion concentrations following MoMHR revision. Between 2005–2012, a single-centre prospective cohort study was undertaken of patients with large-diameter MoMHRs and high blood metal ions requiring revision. Whole blood and urine were collected both pre-revision and post-revision for metal ion analysis.Introduction
Methods
AIS causes a loss of trunk height. This paper documents this loss against sitting height standards and assesses formulae for adjusting height loss back to the standard. A total of 334 patients (84% female) with AIS and no other known systemic disease had sitting height measured. This was compared to standards of sitting height with age and the ratio of height to sitting height with age (HSH). The corrected height was calculated using published formulae and replotted against these standards.Aim:
Methods:
Oxford hip and knee scores are being used by many heath care commissioners to determine whether individual patients are eligible for joint replacement surgery. Oxford scores were not designed for use in deciding whether patients are suitable for surgery and they are not validated as a triage tool. The aim of this study was to assess what effect these predetermined threshold Oxford Scores would have on a contemporary patient cohort. An analysis was undertaken of 4254 pre-operative Oxford scores in patients who had already undergone either hip resurfacing, a total hip, total knee or unicompartmental knee replacement surgery at our institution between 2008 and 2011. We assessed how these scores would affect the decision making pathway determining which patients would be eligible for joint replacement surgery. We also evaluated the effects this would have on patients undergoing surgery in terms of gender, sex, age and type of arthroplasty. 22.4% hip resurfacings, 10.0% of total hip replacements, 7.5% total knee replacements and 11.0% unicompartmental knee replacements would have been declined on the Oxford Scores system. The selection criteria as set by the health care commissioners was found to be ageist as there was a bias against older patients obtaining surgery. There was a bias against different forms of arthroplasty, particularly those patients suitable for resurfacing or unicompartmental knee replacement. It was also sexist as it selectively excluded male patients from surgery. Rather than using pre-operative Oxford scores to discern which patients are eligible for surgery, evaluation of patient factors which are reported to adversely affect the outcome of hip and knee replacement surgery, may offer a better solution to improving quality of care. Oxford scores are undertaken to benchmark a providers performance and not to decide on an individual's suitability for surgery.
Unicompartmental knee arthroplasty provides a good alternative to total knee arthroplasty in patients with isolated medial compartment osteoarthritis. There has been variable reporting in the literature as to whether age and sex affect the survival of unicompartmental knee arthroplasty. The aim of this study was to determine whether age and sex were predictors of failure for the Oxford unicompartmental knee arthroplasty. Details of consecutive patients undergoing Oxford unicompartmental knee arthroplasty at our centre between January 2000 and December 2009 were collected prospectively. Failure of the implant was defined as conversion to total knee arthroplasty. Survival was determined using the Kaplan-Meier method. A Cox proportional hazard model was used to determine the affect of age and sex on survivorship of the prosthesis.Background
Methods
Direct lateral approaches to the hip require detachment and repair of the anterior part of the gluteus medius and minimus tendon attachments. Limping may occur postoperatively due to nerve injury or failure of muscle re-attachment. The aim of this study was to assess the integrity of abductor muscle repairs using a braided wire suture marker. Total hip arthroplasties were inserted using a modified Freeman approach. After repair of the abductor tendons using a 1 PDS suture with interlocking Kessler stitches, a 3–0 braided wire suture marker was stitched into the lower end of the flap. The suture was easily visible on postoperative radiographs and its movement could be measured. Patients were assessed using radiographs and Oxford hip scores collected prospectively.Introduction
Methods
A number of studies have reported on the early failure of the Oxford unicompartmental knee arthroplasty. However, less evidence is available regarding the outcome following revision of failed unicompartmental knee prostheses to total knee arthroplasty. The aims of this study were to determine the time to failure for the Oxford unicompartmental knee arthroplasty and to assess the short-term outcome following revision surgery. Details of consecutive patients undergoing revision of an Oxford unicompartmental knee arthroplasty to a total knee arthroplasty at our centre between January 2000 and December 2009 were collected prospectively. Data was collected on patient demographics, indication for revision surgery, and time to revision from the index procedure. Clinical and radiological outcome following revision arthroplasty was also assessed.Background
Methods
The purpose of our study was three fold; firstly to assess the survival of closing wedge high tibial osteotomies (CWHTO), secondly to assess any clinical factors or radiological alignment which may affect survival and thirdly to assess the change in tibial inclination and patella height. Details of 51 patients undergoing CWHTO for varus gonarthrosis between 1999 and 2007 were assessed for age, BMI, gender, range of movement, meniscal integrity and grade of arthritis. Radiological evaluation included pre and post-operative femoro-tibial axis, tibial slope and patella height. Outcome was also evaluated by Oxford knee score and UCLA activity score. Failure was considered as conversion to arthroplasty.Aims
Methods
The primary aim of this study was to determine the long-term survival of OATS (Osteochondral Autograft Transfer System) (Arthrex, Florida, USA) grafting in our centre and evaluate the reasons for failure, the secondary aim was to ascertain if age, gender, BMI, site or size of OATS graft had any influence on outcome. Details of patients undergoing an OATS procedure from 1999 to 2008 were collected. Loosening, graft degeneration or subsequent surgery in the form of arthroplasty, revision OATS¯ or any other osteochondral procedure was considered as failure. Oxford knee score and UCLA activity score evaluated outcome.Aims
Methods
Unicompartmental knee arthroplasty provides a good alternative to total knee arthroplasty in patients with isolated medial compartment osteoarthritis. There has been variable reporting in the literature as to whether age and sex affect the survival of unicompartmental knee arthroplasty. The aims of this study were to determine whether age and sex were predictors of failure for the Oxford unicompartmental knee arthroplasty.Background
Study aims
A number of studies have reported on the early failure of the Oxford unicompartmental knee arthroplasty. However, less evidence is available regarding the outcome following revision of failed unicompartmental knee prostheses to total knee arthroplasty. The study aims were to determine the time to failure and mode of failure for the Oxford unicompartmental knee arthroplasty and to assess the short-term outcome following revision surgery.Background
Study aims
Monitoring of scoliosis is traditionally done with radiographs, which can be associated with an increased risk of cancer secondary to multiple exposures over many years. This study investigated whether the findings from surface topography can be used to monitor scoliosis curves and how much this method affects outcome scores in patients with scoliosis. This study therefore had two subsets: (1) to investigate whether lateral asymmetry (LA) from ISIS2 surface topography can predict radiographic Cobb angle, providing an alternative non-invasive means of monitoring patients with scoliosis (LA and Cobb subset); and (2) to establish the relationships between the magnitude of the deformity in scoliosis, measured by Cobb angle on radiograph and volumetric asymmetry (VA) with the ISIS2 surface topography, and the patient perception of self-image and mental health, measured with SRS-22 scores (Cobb, VA, and SRS subset). In the LA and Cobb subset, 72 untreated patients with scoliosis (77 curves) with a Cobb angle of 55° or less were included in the study. They had clinical assessment, Cobb angle measurement taken from a standard radiograph, and surface topography done on the same day. A comparison of Cobb angle and LA was done. In the Cobb, VA, and SRS subset, 89 untreated patients with scoliosis were included in the study. They had clinical assessment, Cobb angle measurement of radiograph, and surface topography done on the same day along with SRS-22 questionnaires. A comparison correlation of SRS scores for function, pain, self-image, and mental health against Cobb angle and VA was undertaken. All statistical analysis was done with software R.Introduction
Methods
To establish the relation between the magnitude of the deformity in scoliosis, measured by cobb angle on radiograph & Volumetric asymmetry with the ISIS2 surface topography, and the patient perception of self image and mental health, measured with SRS-22 scores. A total of 89 untreated patients with scoliosis were included in the study. They had clinical assessment, cobb angle measurement of radiograph and surface topography performed on the same day along with SRS-22 questionnaires. The cobb angle was measured by single surgeon using a digital PACS system, who was unaware of the volumetric asymmetry score. Volumetric asymmetry was measured by ISIS2 surface topography performed by a research nurse who was unaware of the cobb angle. Volumetric asymmetry was calculated using standard ISIS2 software. A comparison correlation of SRS scores for function, pain, self image and mental health against cobb angle and volumetric asymmetry was undertaken by clinical scientist. Scores for patient satisfaction to treatment was excluded as these were untreated patients. Statistical analysis was performed using cor. test on software RPurpose of the study
Methodology
Monitoring of scoliosis is traditionally done with radiographs which can be associated with an increased risk of cancer secondary to multiple exposures over many years. This study investigates whether lateral asymmetry (LA) from ISIS2 surface topography can predict radiographic cobb angle, to provide an alternative non- invasive means of monitoring scoliosis patients. A total of 72 untreated patients with scoliosis (77 curves) with a Cobb angle of 55 degrees or less were included in the study. They had clinical assessment, cobb angle measurement taken from a standard radiograph and surface topography done on the same day. The cobb angle were measured by single surgeon using digital PACS system. The surgeon was unaware of the LA score. Lateral asymmetry was measured using ISIS2 surface topography done by a research nurse who was also unaware of the cobb angle as previously described. Lateral asymmetry was calculated using the standard ISIS2 software. A comparison of cobb angle and LA was performed. Linear regression analysis was performed to define an equation predicting Cobb from LA. The predicted Cobb angles were then compared with the measured radiographic Cobb angles using Bland-Altman analysis. All statistical analysis was carried out using R.Purpose of the study
Methods
To assess the survival of revision knee replacements at our institution and to identify prognostic factors that predict failure in revision knee surgery. This was a retrospective review of 52 patients who had undergone revision knee surgery as identified by hospital clinical coding. Patient demographics, physiological parameters, reason for revision, type of revision implant and last date of follow up were recorded from the medical records. Implant survival was analysed both from the index primary procedure to revision and from definitive reconstruction at revision to re-operation for any cause.Aim
Materials and methods
We prospectively reviewed 2440 Cemented Anantomical (side specific) AGC total knee replacements performed on 2074 patients between 2002 and 2008 in our unit. The surgery was performed by a number of surgeons, both Consultant and Trainee grades. 1357 underwent PCL sacrificing surgery with implantation of Posterior Stabilised Femoral Implant (Cam and Grove) and 1083 underwent PCL retaining surgery with implantation of a Non-Stabilised Femoral Implant. The mean age at date of surgery for Posterior Stabilised prosthesis was 69 years (range 23-94) and Non-Posterior Stabilised prosthesis was 70 (range 33-97) with no significant difference p< 0.05 (C.I 95%). Follow up at present mean 4 years (range 1-6 years). 11 patients underwent secondary patella resurfaced for anterior knee pain at a mean of 1.5 years following the index procedure (range 0.5-4.1 years) with 6 patients reporting a marked improvement in anterior knee pain post operatively. 3 patients underwent removal of patella buttons for symptomatic loosening at a mean of 2.7 years follow index procedure. A total of 17 patients underwent a revision of either tibial or femoral components (0.7%). Indications for revision were infection in 11 patients, gross instability in 1 patient, periprosthetic fracture in 1 patient, persistent stiffness in 1 patient. 3 patients underwent revision for symptomatic loosening of the tibial component at a mean of 2.9 years (range 1.1-4.0). These short to medium term results for the Anatomic AGC total knee replacement agree with published results from other centres.
Secondary osteoarthritis in a dysplastic hip is a surgical challenge. Severe leg length discrepancies and torsional deformities add to the problem of inadequate bony support available for the socket. Furthermore, many of these patients are young and wish to remain active, thereby jeopardising the long-term survival of any arthroplasty device. For such severely dysplastic hips, the Birmingham Hip Resurfacing (BHR) device provides the option of a dysplasia component, a hydroxyapatite-coated porous uncemented socket with two lugs to engage neutralisation screws for supplementary fixation into the solid bone of the ilium more medially. The gap between the superolateral surface of the socket component and the false acetabulum is filled with impacted bone graft. One hundred and thirteen consecutive dysplasia BHRs performed by the senior author (DJWM) for the treatment of severely arthritic hips with Crowe grade II and III dysplasia between 1997 and 2000 have been reviewed at a minimum five year follow-up. There were 106 patients (59M and 47F). Eighty of the 113 hips were old CDH or DDH, 29 were destructive primary or secondary arthritis with wandering acetabulae and four were old fracture dislocations of the hip. Mean age at operation was 47.5 years (range 21 to 68 years – thirty-six men and forty-four women were below the age of 55 years). There were two failures (1.8%) out of the 113 hips at a mean follow-up of 6.5 years (range 5 to 8.3 years). One hip failed with a femoral neck fracture nine days after the operation and another failed due to deep infection at 3.3 years.Introduction
Methods and results
Mean patient age at first revision was 50.8 years (range: 18.4–75.9 years), at a median of 1.8 years (25th percentile 0.03 years, 75th percentile 4.6 years) after the primary operation. 29 (35%) resurfacings were revised for aseptic loosening, 23 (27%) for periprosthetic fracture, 8 (10%) for component malalignment, 8 (10%) for pain alone, 4 (5%) for infection, 4 (5%) for avascular necrosis and 4 (5%) for instability.
We report the survival at ten years of 173 consecutive Birmingham Hip Resurfacing’s implanted between August 1997 and August 1998 at a single institution. Failure was defined as revision of either the acetabular or femoral component for any reason during the study period. The survival at the end of ten years was 96.5% (95%c. i. 89.1 – 99.5%) The mean age of the patients at implantation was 50 years (range 15 – 75). There were 124 (72%) male cases and 49 (28%) female cases. 123 (71%) cases had the diagnosis of osteoarthritis, 9 osteonecrosis, 5 rheumatoid and 3 DDH. The posterior approach was used in 154 (89%) cases and anterolateral in 19 (11%). Cases were performed by 5 different surgeons. There were 5 revisions, 9 unrelated deaths and 18 were lost to follow-up beyond 5 years. Two revisions occurred for infection (6 months and 2 years). A revision at 3.5 years for acetabular loosening and two further at 6.4 and 7.9 years due to avascular necrosis of the femoral head and collapse were performed. No other revisions are impending. The median pre-operative oxford hip score was 61% (IQR 48–73) and the median 10 year score was 7% (IQR 0–31) for 110 completed forms. Further analysis of the total resurfacing database at this institution of 2775 cases was performed. Cox-proportional hazard analysis identified that component size and pre-operative diagnosis were significantly associated with failure. Although females may initially appear to have a greater risk of revision this is related to differences in the size and pre-operative diagnosis between the genders. This study confirms that hip resurfacing using a metal-on-metal bearing of known provenance can provide a solution in the medium term for the younger more active adult who requires surgical intervention for hip disease.
The mean difference in cord chromium between the study and control groups is not statistically significant (p >
0.05), although cord cobalt in the study group is significantly higher (p <
0.01) than that in controls. Whilst there is a four-fold elevation of maternal cobalt in the study patients and an almost 7-fold increase in maternal chromium levels as compared to the control group, the elevation in the cord cobalt and chromium in the study group are smaller.
Metal-on-metal hip resurfacing is increasingly common. Patients suitable for hip resurfacing are often young, more active, may be in employment and may have bilateral disease. One-stage bilateral total hip replacement has been demonstrated to be as safe as a two-stage procedure and more cost effective. The aim of this study was to compare the in-patient events, outcome and survival in patients undergoing one-stage resurfacing with a two-stage procedure less than one-year apart.
No patients have undergone a revision procedure during the study period and no patient is awaiting revision surgery.
ISIS2 is a surface topography system measuring the three-dimensional shape of the back in scoliosis patients using digital photography with structured light. Lateral asymmetry is the ISIS clinical parameter estimating the curve of the spine in the coronal plane [
An automated system has been developed to measure three-dimensional back shape in scoliosis patients using structured light. The low-cost system uses a digital camera to acquire a photograph of a patient with coloured markers on palpated bony landmarks, illuminated by a pattern of horizontal lines. A user-friendly operator interface controls the lighting and camera and leads the operator through the analysis. The system presents clinical information about the shape of the patient’s deformity on screen and as a printed report. All patient data (both photographs and clinical results) are stored in an integral database. The database can be interrogated to allow successive measurements to be plotted for monitoring the deformity. The system is non-invasive, requiring only a digital photograph to be taken of the patient’s back. Identification of the bony landmarks allows all clinical data to be related to body axes. This reduces the effects of variability in patient stance. Measurement of a patient, including undressing, landmark marking and dressing, can be carried out in approximately 10 minutes. The clinical results presented are based on the old ISIS report. This includes:
transverse sections at 19 levels from vertebra prominens to sacrum. coronal views of the line of spinous processes on the surface of the back and the line estimated to be through the centres of the vertebrae; lateral asymmetry, a parameter analogous to Cobb angle, is calculated from the latter. sagittal views of the line of spinous processes on the surface of the back, including kyphosis and lordosis data. Additionally, a three-dimensional wire-frame plot, a coloured contour plot and a pair of bilateral asymmetry plots give visual impressions of any deformity in the measured back.
The extremely low failure rate in the medium term proves the suitability of resurfacing in young active patients. However, caution needs to be exercised until long term results are available.
Bland-Altman analysis (Figure 1A) shows the limits of agreement between serum and WB are unacceptably wide (1.7 to -5.1 for chromium) suggesting poor agreement.
To determine the ten-year survivorship of the Original M E Muller Straight Stem Total Hip Replacement System with emphasis on the longevity of the femoral component in accordance with guidelines published by the National Institute of Clinical Excellence, 266 consecutive hip arthroplasties using the above prosthesis were performed by the senior author between 1983 and 1992. 24 patients were lost to follow-up. Of the remaining 242 patients 80 were male and 162 female. The mean age was 67.49 years. The diagnosis for the majority of patients was osteoarthritis of the hip joint. Pre-operative planning was carried out and the patients were scored using Charnley’s modification of the d’ Aubigne and Postel numerical grading system A mono-bloc stem with a 32-millimeter head used via the trans gluteal approach recommended by Muller. Following discharge serial follow-up consisted of both clinical and radiological evaluation. The data was prospectively stored on a Microsoft access database. The survival of the prosthesis using revision for aseptic loosening as an end-point was calculated by actuarial analysis. 135 patients attended their ten-year follow-up. 97% of patients had good to excellent pain relief and improvement in movement of the joint following surgery. 38% had good to excellent mobility with the remaining having restricted mobility due to associated co-morbid factors. Only in 3% of patients was mobility restricted as a result of the arthroplasty. 7 revisions were carried out for aseptic loosening, all as a result of failure of the acetabular component. The cumulative survival for this hip replacement system was 95.9% and that for the femoral component was 100% at 10 years. The Muller Straight Stem femoral component is based on a press-fit concept and gives predictable long-term results when recommended surgical technique is followed. This series confirms the reliability of the stem design and satisfies the NICE guidelines.
Metal on metal hip resurfacing was introduced in 1992 by Derek McMinn initially using an all cementless device and then an all cemented device. A hybrid resurfacing with a cemented femoral component and a cementless acetabular component was introduced in 1994. The manufacturer of the hybrid hip resurfacing was changed in 1996. Since 1997 the Birmingham hip resurfacing has been in continuous use. The device is approved by NICE (National Institute for Clinical Excellence) for use within the NHS in patients with Osteoarthritis of the hip. The device is not yet approved for use in patients with Rheumatoid Arthritis and other types of inflammatory arthritis. There are concerns regarding bone quality in rheumatoid patients, which may result in a high incidence of component loosening or femoral neck fracture. Conventional total hip replacement is a successful procedure in inflammatory arthritis however with modern treatments producing increased activity levels there are concerns about polyethylene wear. The author has performed metal on metal hip resurfacing in patients with inflammatory arthritis over the past 12 years. A total of 170 patients have been operated on with 198 resurfacings. 33% of patients have a diagnosis of some type of inflammatory arthritis. The outcomes have been assessed using Oxford hip scores and long term clinical and radiological review. Our results indicate that there is a minimal risk of femoral neck fracture and a minimal risk of component loosening when the device is used with this approach in patients with inflammatory arthritis.
Hip Resurfacing has always been an attractive concept for the treatment of hip arthritis in younger patients. Introduction of modern metal-on-metal hip resurfacing in 1991 in Birmingham, UK made this concept a reality. In the early years, resurfacings were used only by a few experienced surgeons. From 1997, Birmingham Hip Resurfacings (BHRs) are being widely used in younger and more active patients. A breakdown of the ages at operation in the regional NHS hospital in Birmingham during the period April 1999 to March 2004 show that the mean age of metal-metal resurfacings is 51 years and the mean age of total hip replacements is 70 years. At a 3.7 to 10.8 year follow-up (mean follow-up 5.8 years), the cumulative survival rate of metal-metal resurfacing in young active patients with osteoarthritis is 99.8%. In the long term, none of these patients were constrained to change their occupational or leisure activities as a result of the procedure. The overall revision rate of BHRs in all ages and all diagnoses is also very low (19 out of 2167 [0.88%] with a maximum follow-up of 7.5 years). Improvements in instrumentation and a minimally invasive approach developed by the senior author have made this successful device even more attractive. Although objective evidence does not support the fact that the longer approach was any more invasive than the minimal route, patient feedback shows that it is very popular with them. While minimal approach is indeed appealing, it has a steep learning curve. In the early phase of this curve, care should be taken to avoid the potential risk of suboptimal component placement which can adversely affect long-term outcome. It is true that metal-metal bearings are associated with elevated metal ion levels. In vitro studies of BHRs show that they have a period of early run-in wear. This is not sustained in the longer term. These findings are found to hold true in vivo as well, in our studies of 24- hour cobalt output and whole blood metal ion levels. Epidemiological studies show that historic metal-metal bearings are not associated with carcinogenic effects in the long-term. Metal ion levels in patients with BHRs are in the same range as the levels found in those with historic metal-metal total hip replacements.
This study reports the early results of Birmingham Hip Resurfacing in a group of patients less than 25 years of age. We assessed over a period of 5 years all patients who underwent hip resurfacing who were under the age of 25. Thirty-eight patients underwent 43 hip resurfacing procedures for a variety of diagnoses. This included 15 with Developmental Dysplasia of the Hip (DDH), 13 with Osteonecrosis (ON) of the femoral head, and 7 with End-stage Spastic Hip Disease (ESSHD). We assessed complications, failure and revision rates. Patients completed co-op and oxford hip scores and both clinical and radiographic assessments. At a follow-up of a maximum of 5 years the survival rate was 93% with a further 7% showing radiographic features of failure. Thirteen hips (30%) had a femoral osteotomy at the time of resurfacing allowing correction of length and rotation with no apparent increase in complications. Those who required revision were successfully converted to metal- metal total hip replacement. Our results report the first use of this type of prosthesis in a group of patients under the age of 25 and demonstrate comparable results to standard treatments at this early stage. This study supports the use of hip resurfacing as alternative to conventional treatments for this complex group of patients.
The weights of evidence (WE) are logs of the likelihood ratios and can be added and a probability then calculated. e.g. a 36 yr old with a 10cm, deep, painless lump that is increasing in size scores −0.39 + 0.4 + 0.4 – 0.11 + 0.58 = 0.88. This equates to a risk of the lump being malignant of 70%.
The growing interest in the use of metal on metal bearings in the treatment of end stage hip arthritis in the young has raised the need to monitor metal ion levels in these patients. Blood levels are good indices of the safety of these devices. Total wear/corrosion over a given time period is best estimated from 12 or 24-hour urine collections. Whole blood samples of 52 patients with metal on metal hip arthroplasties were analysed for levels of chromium, cobalt and molybdenum using high-resolution induction coupled plasma mass-spectrometry. Fifteen of these were in an older age group (mean age 75.3years) and had metal on metal hip replacements performed 19–28 years before the assessment. The rest (37) were younger (mean age 52.9 years) and had hip resurfacings performed in the last 4 years. The results show higher levels of ions than those found in the normal population. This agrees with other studies. However we found no significant difference between the levels in the older patients with THR and the younger patients with hip resurfacing. In another study, urine collections from 78 patients who had hip resurfacings in the past and are now at different postoperative durations (2, 4, 6, 8, 10, 12, 18, 24 and 36-month periods) were analysed for metal ions using the same technique. The mean levels show an increase compared to the preoperative values but this increase is not statistically significant. The urinary excretion of cobalt in these groups have also been compared with the expected cobalt release due to corrosion in this alloy. They were found to rise above the corrosion levels only in the 8–12 month period, possibly due to “run-in” of the bearing. It can be concluded that the ion levels can be attributed mainly to corrosion and there is minimal contribution from wear.
Between 1965 and 1973 a total of 808 McKee-Farrar metal-on-metal cemented total hip arthroplasties were performed in the Norfolk and Norwich Hospital. Of these, 230 surviving arthroplasties have been reviewed at average follow-up of 13.9 years. There were good or excellent results in 49% of the arthroplasties as judged by the Harris hip score with 78% of these having little or no pain. A comprehensive radiographic analysis was undertaken and a survivorship study of 81% of the total number of prostheses is presented.
Mechanical abnormalities of the patellofemoral joint are among the many causes that have been suggested for adolescent knee pain. This study seeks to identify these factors. Measurements of joint mobility and lower limb morphology were made on 446 pupils at a comprehensive school, 136 of whom had suffered knee pain in the previous year. The pupils with symptoms enjoyed sporting activities significantly more than their symptom-free contemporaries. Joint mobility, the Q-angle, genu valgum and anteversion of the femoral neck were not significantly different between those pupils with and those without anterior knee pain. Data on lower limb morphology of normal adolescents are presented. Examination of 52 hospital outpatients aged 13 to 36 years with anterior knee pain produced results comparable with those for the pupils. It is concluded that chronic overloading, rather than faulty mechanics, is the dominant factor in the genesis of anterior knee pain in adolescent patients.