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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_11 | Pages 21 - 21
1 Jun 2016
Matharu G Berryman F Brash L Pynsent P Dunlop D Treacy R
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Introduction

We investigated whether blood metal ions could effectively identify bilateral metal-on-metal hip patients at risk of adverse reactions to metal debris (ARMD).

Patients and methods

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).


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_7 | Pages 99 - 99
1 May 2016
Ziaee H Daniel J Matharu G Pynsent P McMinn D
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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.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_7 | Pages 100 - 100
1 May 2016
Ziaee H Matharu G Daniel J Pynsent P McMinn D
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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.


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_12 | Pages 25 - 25
1 Nov 2015
Matharu G Daniel J Ziaee H Pynsent P McMinn D
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Introduction

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.

Methods

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.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_6 | Pages 1 - 1
1 Apr 2014
Price A Gardner A Baker D Berryman F Pynsent P
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Aim:

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.

Methods:

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.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 195 - 195
1 Jan 2013
Robb C McBryde C Caddy S Thomas A Pynsent P
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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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 189 - 189
1 Sep 2012
Matharu G Robb C Baloch K Pynsent P
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Background

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.

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 188 - 188
1 Sep 2012
Matharu G Thomas A Pynsent P
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Introduction

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.

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 190 - 190
1 Sep 2012
Matharu G Robb C Baloch K Pynsent P
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Background

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.

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 25 - 25
1 Jul 2012
Robb C Dixon J Parker L Baloch K Pynsent P
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Aims

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.

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 20 - 20
1 Jul 2012
Robb C El-Sayed C Baloch K Pynsent P
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Aims

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.

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 28 - 28
1 Jul 2012
Matharu G Robb C Baloch K Pynsent P
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Background

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.

Study aims

The aims of this study were to determine whether age and sex were predictors of failure for the Oxford unicompartmental knee arthroplasty.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 54 - 54
1 Jul 2012
Matharu G Robb C Baloch K Pynsent P
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Background

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.

Study aims

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXVII | Pages 22 - 22
1 Jun 2012
Kotecha A Berryman F Baker D Pynsent P Gardner A Marks D Spilsbury J
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Introduction

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).

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XX | Pages 1 - 1
1 May 2012
Kotecha AK Berryman F Baker D Pynsent P Gardner A Marks D Spilsbury J
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Purpose of the study

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.

Methodology

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 R


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XX | Pages 2 - 2
1 May 2012
Kotecha AK Berryman F Baker D Pynsent P Gardner A Marks D Spilsbury J
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Purpose of the study

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.

Methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 52 - 52
1 Mar 2012
Youssef B Revell M McBryde C Pynsent P
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Aim

To assess the survival of revision knee replacements at our institution and to identify prognostic factors that predict failure in revision knee surgery.

Materials and methods

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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 5 - 5
1 Mar 2012
Cockshott S Adams D Carter S Jeys L Pynsent P
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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.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_III | Pages 145 - 145
1 Feb 2012
Pradhan C Daniel J Ziaee H Pynsent P McMinn D
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Introduction

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.

Methods and results

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.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 549 - 549
1 Nov 2011
Bucknall V McBryde C Revell M Pynsent P
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Introduction: The Oxford hip score (OHS) instrument is used to assess pain and disability before and after hip arthroplasty and may be used as a standard for auditing pre and post-operative patients. It has been suggested that patients with a low pre-operative hip score (< 25th percentile) should be carefully assessed before surgical management is employed. This study aimed to determine the factors that influence a surgeon’s decision to undertake hip arthroplasty in patients with a low pre-operative hip score.

Methods: All patients who underwent hip arthroplasty over a two month period (n=121) were included. Of these, four pre-operative OHS questionnaires were missing. The remaining (117) were validated and those scoring below the published 25th percentile (58.3%) were selected (n=35), termed the ‘low-group’. Individual OHS responses scored 0–4 were examined (0 = no impairment and 4 = worst impairment) and the proportional differences between the responses for this group and the remaining 75% were investigated. The pre-operative radiographic Tönnis stage of osteoarthritis was determined.

Results: The median cohort OHS was 68.8% (IQR = 50–79%). Of the questions that scored highly, 59% were purely pain related, 14% function and 27% both. 66% of patients experienced moderate/severe pain and 31% suffered night pain. The ‘low-group’ never scored 4 (worst impairment) on questions concerning washing, transport, shopping, stairs and work. However, 57% scored 4 on questions encompassing a pain component. In all questions except donning socks and walking, the proportion of 4 in the ‘low-group’ was significantly different to the remainder of the cohort. Tönnis grade 3 (osteophytes and advanced loss of joint space) osteoarthritis predominated (49%).

Conclusion: Arthroplasty in patients with low pre-operative OHS is influenced mainly by pain affecting quality of life. Half of these patients also have advanced features of osteoarthritis on radiographic assessment despite the low scores.