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The Bone & Joint Journal
Vol. 106-B, Issue 1 | Pages 38 - 45
1 Jan 2024
Leal J Mirza B Davies L Fletcher H Stokes J Cook JA Price A Beard DJ

Aims

The aim of this study was to estimate the incremental use of resources, costs, and quality of life outcomes associated with surgical reconstruction compared to rehabilitation for long-standing anterior cruciate ligament (ACL) injury in the NHS, and to estimate its cost-effectiveness.

Methods

A total of 316 patients were recruited and randomly assigned to either surgical reconstruction or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment). Healthcare resource use and health-related quality of life data (EuroQol five-dimension five-level health questionnaire) were collected in the trial at six, 12, and 18 months using self-reported questionnaires and medical records. Using intention-to-treat analysis, differences in costs, and quality-adjusted life years (QALYs) between treatment arms were estimated adjusting for baseline differences and following multiple imputation of missing data. The incremental cost-effectiveness ratio (ICER) was estimated as the difference in costs divided by the difference in QALYs between reconstruction and rehabilitation.


Bone & Joint Open
Vol. 4, Issue 12 | Pages 923 - 931
4 Dec 2023
Mikkelsen M Rasmussen LE Price A Pedersen AB Gromov K Troelsen A

Aims

The aim of this study was to describe the pattern of revision indications for unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) and any change to this pattern for UKA patients over the last 20 years, and to investigate potential associations to changes in surgical practice over time.

Methods

All primary knee arthroplasty surgeries performed due to primary osteoarthritis and their revisions reported to the Danish Knee Arthroplasty Register from 1997 to 2017 were included. Complex surgeries were excluded. The data was linked to the National Patient Register and the Civil Registration System for comorbidity, mortality, and emigration status. TKAs were propensity score matched 4:1 to UKAs. Revision risks were compared using competing risk Cox proportional hazard regression with a shared γ frailty component.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_13 | Pages 88 - 88
7 Aug 2023
Ahmed I Dhaif F Khatri C Parsons N Hutchinson C Price A Staniszewska S Metcalfe A
Full Access

Abstract

Introduction

Recent research has questioned the role of arthroscopic meniscectomy in patients with a meniscal tear leading to the development of treatment recommendations for these patients. There is a clear need to understand patient perceptions of living with a meniscal tear in order to plan future research and treatment guidelines.

Aims

To explore the experiences and expectations of treatment of young patients with a meniscal tear of the knee


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_13 | Pages 87 - 87
7 Aug 2023
Ahmed I Dhaif F Khatri C Parsons N Hutchinson C Staniszewska S Price A Metcalfe A
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Abstract

Background

Meniscal tears affect 222 per 100,000 of the population and can be managed non-operatively or operatively with an arthroscopic partial meniscectomy (APM), meniscal repair or meniscal transplantation. The purpose of this review is to summarise the outcomes following treatment with a meniscal tear and explore correlations between outcomes.

Methodology

A systematic review was performed of MEDLINE, EMBASE, AMED and the Cochrane Central Register of Controlled Trials to identify prospective studies describing the outcomes of patients with a meniscal tear. Comparisons were made of outcomes between APM and non-operative groups. Outcomes were graphically presented over time for all treatment interventions. Pearson's correlations were calculated between outcome timepoints.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_13 | Pages 89 - 89
7 Aug 2023
Ahmed I Dhaif F Bowes M Parsons N Hutchinson C Staniszewska S Price A Metcalfe A
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Abstract

Introduction

Previous research has demonstrated no clinically significant benefit of arthroscopic meniscectomy in patients with a meniscal tear, however, patients included in these studies would not meet current treatment recommendations. Prior to further randomised controlled trials (RCTs) research is needed to understand a younger population in more detail.

Aim

To describe the baseline characteristics of patients with a meniscal tear and explore any association between baseline characteristics and outcome.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_11 | Pages 32 - 32
7 Jun 2023
Howgate D Roberts PG Palmer A Price A Taylor A Rees J Kendrick B
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Primary total hip replacement (THR) is a successful and common operation which orthopaedic trainees must demonstrate competence in prior to completion of training. This study aimed to determine the impact of operating surgeon grade and level of supervision on the incidence of 1-year patient mortality and all-cause revision following elective primary THR in a large UK training centre.

National Joint Registry (NJR) data for all elective primary THR performed in a single University Teaching Hospital from 2005–2020 were used, with analysis performed on the 15-year dataset divided into 5-year temporal periods (B1 2005–2010, B2 2010–2015, B3 2015–2020). Outcome measures were mortality and revision surgery at one year, in relation to lead surgeon grade, and level of supervision for trainee-led operations.

9999 eligible primary THR were undertaken, of which 5526 (55.3%) were consultant led (CL), and 4473 (44.7%) trainees led (TL). Of TL, 2404 (53.7%) were non-consultant supervised (TU), and 2069 (46.3%) consultant supervised (TS). The incidence of 1-year patient mortality was 2.05% (n=205), and all-cause revision was 1.11% (n=111). There was no difference in 1-year mortality between TL (n=82, 1.8%) and CL (n=123, 2.2%) operations (p=0.20, OR 0.78, CI 0.55–1.10). The incidence of 1-year revision was not different for TL (n=56, 1.3%) and CL (n=55, 1.0%) operations (p=0.15, OR 1.37, CI 0.89–2.09). Overall, there was no temporal change for either outcome measure between TL or CL operations. A significant increase in revision within 1-year was observed in B3 between TU (n=17, 2.7%) compared to CL (n=17, 1.0%) operations (p=0.005, OR 2.81, CI 1.35–5.87).

We found no difference in 1-year mortality or 1-year all-cause revision rate between trainee-led primary THR and consultant-led operations over the entire fifteen-year period. However, unsupervised trainee led THR in the most recent 5-year block (2015–2020) has a significantly increased risk of early revision, mainly due to instability and prosthetic joint infection. This suggests that modern surgical training is having a detrimental effect on THR patient outcomes. More research is needed to understand the reasons if this trend is to be reversed.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_9 | Pages 52 - 52
17 Apr 2023
Abram S Sabah S Alvand A Price A
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Revision knee arthroplasty is a complex procedure with the number and cost of knee revision procedures performed per year expected to rise. Few studies have examined adverse events following revision arthroplasty.

The objective of this study was to determine rates of serious adverse events in patients undergoing revision knee arthroplasty with consideration of the indication for revision (urgent versus elective indications) and to compare these with primary arthroplasty and re-revision arthroplasty.

Patients undergoing primary knee arthroplasty were identified in the UK Hospital Episode Statistics. Subsequent revision and re-revision arthroplasty procedures in the same patients and same knee were identified. The primary outcome was 90-day mortality and a logistic regression model was used to investigate factors associated with 90-day mortality and secondary adverse outcomes including infection (undergoing surgery), pulmonary embolism, myocardial infarction, stroke. Urgent indications for revision arthroplasty were defined as infection or fracture, and all other indications were included in the elective indications cohort.

939,021 primary knee arthroplasty cases were included of which 40,854 underwent subsequent revision arthroplasty, and 9,100 underwent re-revision arthroplasty. Revision surgery for elective indications was associated with a 90-day rate of mortality of 0.44% (135/30,826; 95% CI 0.37-0.52) which was comparable to primary knee arthroplasty (0.46%; 4,292/939,021; 95% CI 0.44-0.47). Revision arthroplasty for infection, however, was associated with a much higher mortality of 2.04% (184/9037; 95% CI 1.75-2.35; odds ratio [OR] 3.54; 95% CI 2.81-4.46), as was revision for periprosthetic fracture at 5.25% (52/991; 95% CI 3.94-6.82; OR 6.23; 95% CI 4.39-8.85). Higher rates of pulmonary embolism, myocardial infarction, and stroke were also observed in the infection and fracture cohort.

These findings highlight the burden of complications associated with revision knee arthroplasty. They will inform shared decision-making for patients considering revision knee arthroplasty for elective indications. Patients presenting with infection of a knee arthroplasty or a periprosthetic fracture are at very high risk of adverse events. It is important that acute hospital services and tertiary referral centres caring for these patients are appropriately supported to ensure appropriate urgency and an anticipation for increased care requirements.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 34 - 34
1 Jul 2022
Abram S Sabah S Alvand A Price A
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Abstract

Introduction

The objective of this study was to determine rates of serious adverse events in patients undergoing revision knee arthroplasty with consideration of the indication for revision and compare these with primary knee arthroplasty.

Methodology

Primary and revision arthroplasty procedures were identified in the national Hospital Episode Statistics and were linked by patient and side. A logistic regression model was used to investigate factors associated with 90-day mortality (primary outcome) and secondary serious adverse outcomes. Urgent indications for revision arthroplasty were defined as infection or fracture; other indications (e.g. loosening, instability, wear) were included in the elective cohort.


Abstract

Introduction

Cementless fixation of Oxford Unicompartmental Knee Replacements (UKRs) is an alternative to cemented fixation, however, it is unknown whether cementless fixation is as good long-term. This study aimed to compare primary and long-term fixation of cemented and cementless Oxford UKRs using radiostereometric analysis (RSA).

Methodology

Twenty-nine patients were randomised to receive cemented or cementless Oxford UKRs and followed for ten years. Differences in primary fixation and long-term fixation of the tibial components (inferred from 0/3/6-month and 6-month/1-year/2-year/5-year/10-year migration, respectively) were analysed using RSA and radiolucencies were assessed on radiographs. Migration rates were determined by linear regression and clinical outcomes measured using the Oxford Knee Score (OKS).


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 63 - 63
1 Jul 2022
Sabah S Fritsch LV Price A Alvand A
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Abstract

Introduction

A revision knee replacement (rKR) network model has been introduced in the UK to improve clinical outcomes for patients and reduce healthcare costs. However, the current practice of different types of surgical unit is not well understood. The aim of this study was to answer: “How complex are rKR cases at a Major Revision Centre (MRC)?”

Methodology

Retrospective cohort study at the Nuffield Orthopaedic Centre, Oxford from 2015 - 2018. Case complexity was classified using the Revision Knee Complexity Classification (RKCC). Referral source, technical details of surgery and hospital admission impact were recorded.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 77 - 77
1 Jul 2022
Sabah S Sina J Alvand A Beard D Price A
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Abstract

Introduction

Anxiety and depression are risk factors for poor outcome following knee replacement surgery. The aim of this study was to investigate the prevalence of anxiety and depression before and after primary (pKR) and revision knee replacement (rKR).

Methodology

Retrospective cohort study. 315,720 pKR and 12,727 rKR recruited from the NHS Patient Reported Outcome Measures (PROMs) programme from 2013–2021. Anxiety and depression were defined using: (i) Survey question: “Have you been told by a doctor that you have depression? Yes/No”; (ii) EQ-5D anxiety/depression domain. Rates of EQ-5D anxiety/depression were investigated at baseline and at 6-months following surgery. The prevalence of depression was investigated by patient age and gender.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 79 - 79
1 Jul 2022
Fritsch LV Sabah S Xu J Jackson W Merle C Price A Alvand A
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Abstract

Introduction

Re-revision knee replacement (RR-KR) is complex surgery, with a significant impact on individual patients and health resource use. The aim of this study was to investigate early patient-relevant outcomes following RR-KR.

Methodology:

206 patients (250 knees) undergoing RR-KR were recruited from a major revision centre between 2015–2018. Patient-relevant outcomes assessed were: implant survivorship, complications (90-days), joint function and quality of life (final follow-up). Risk factors for further revision surgery at 1 year were investigated using multiple logistic regression.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 62 - 62
1 Jul 2022
Sabah S Knight R Alvand A Beard D Price A
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Abstract

Introduction

Our aim was to investigate trends in the incidence rate and main indication for revision knee replacement (rKR) over the past 15 years in the UK.

Methodology

Cross-sectional study from 2006 - 2020 using data from the National Joint Registry (NJR). Crude incidence rates were calculated using population statistics from the Office for National Statistics.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_7 | Pages 30 - 30
1 Jul 2022
Middleton R Jackson W Alvand A Bottomley N Price A
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Abstract

Background

Since 2012 we have routinely used the cementless Oxford medial unicompartmental knee arthroplasty (mUKA), with microplasty instrumentation, in patients with anteromedial osteoarthritis (AMOA) meeting modern indications. We report the 10-year survival of 1000 mUKA with minimum 4-year follow-up.

Methods

National Joint Registry (NJR) surgeon reports were interrogated for each senior author to identify the first 1,000 mUKAs performed for osteoarthritis. A minimum of 4 years follow-up was required. There was no loss to follow-up. The NJR status of each knee was established. For each mUKA revision the indication and mechanism of failure was determined using local patient records. The 10-year implant survival was calculated using life-table analysis.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_16 | Pages 28 - 28
1 Dec 2021
Ahmed I Moiz H Carlos W Edwin C Staniszewska S Parsons N Price A Hutchinson C Metcalfe A
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Abstract

Objectives

Magnetic resonance imaging (MRI) is one of the most widely used investigations for knee pain as it provides detailed assessment of the bone and soft tissues. The aim of this study was to report the frequency of each diagnosis identified on MRI scans of the knee and explore the relationship between MRI results and onward treatment.

Methods

Consecutive MRI reports from a large NHS trust performed in 2017 were included in this study. The hospital electronic system was consulted to identify whether a patient underwent x-ray prior to the MRI, attended an outpatient appointment or underwent surgery.


Bone & Joint Research
Vol. 9, Issue 9 | Pages 623 - 632
5 Sep 2020
Jayadev C Hulley P Swales C Snelling S Collins G Taylor P Price A

Aims

The lack of disease-modifying treatments for osteoarthritis (OA) is linked to a shortage of suitable biomarkers. This study combines multi-molecule synovial fluid analysis with machine learning to produce an accurate diagnostic biomarker model for end-stage knee OA (esOA).

Methods

Synovial fluid (SF) from patients with esOA, non-OA knee injury, and inflammatory knee arthritis were analyzed for 35 potential markers using immunoassays. Partial least square discriminant analysis (PLS-DA) was used to derive a biomarker model for cohort classification. The ability of the biomarker model to diagnose esOA was validated by identical wide-spectrum SF analysis of a test cohort of ten patients with esOA.


Bone & Joint Open
Vol. 1, Issue 8 | Pages 474 - 480
10 Aug 2020
Price A Shearman AD Hamilton TW Alvand A Kendrick B

Introduction

The aim of this study is to report the 30 day COVID-19 related morbidity and mortality of patients assessed as SARS-CoV-2 negative who underwent emergency or urgent orthopaedic surgery in the NHS during the peak of the COVID-19 pandemic.

Method

A retrospective, single centre, observational cohort study of all patients undergoing surgery between 17 March 2020 and 3May 2020 was performed. Outcomes were stratified by British Orthopaedic Association COVID-19 Patient Risk Assessment Tool. Patients who were SARS-CoV-2 positive at the time of surgery were excluded.


The Bone & Joint Journal
Vol. 102-B, Issue 7 | Pages 950 - 958
1 Jul 2020
Dakin H Eibich P Beard D Gray A Price A

Aims

To assess how the cost-effectiveness of total hip arthroplasty (THA) and total knee arthroplasty (TKA) varies with age, sex, and preoperative Oxford Hip or Knee Score (OHS/OKS); and to identify the patient groups for whom THA/TKA is cost-effective.

Methods

We conducted a cost-effectiveness analysis using a Markov model from a United Kingdom NHS perspective, informed by published analyses of patient-level data. We assessed the cost-effectiveness of THA and TKA in adults with hip or knee osteoarthritis compared with having no arthroplasty surgery during the ten-year time horizon.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_7 | Pages 10 - 10
1 May 2018
Monk P Boyd R Brown C Gibbons M Alvand A Price A
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The optimal correction of the weight bearing line during High Tibial Osteotomy has not been determined. We used finite element modelling to simulate the effect that increasing opening wedge HTO has on the distribution of stress and pressure through the knee joint during normal gait.

Subject-specific models were developed by combining geometry from 7T MRI scans and applied joint loads from ground reaction forces measured during level walking. Baseline stresses and pressures on the articulating proximal tibial cartilage and menisci were calculated. Progressive osteotomies were then simulated to shift the weight-bearing line from the native alignment towards/into the lateral compartment (between 40 – 80% of medial-lateral tibial width). Changes in calculated stresses and pressures were recorded.

Both stress and pressure decreased in the medial compartment and increased in the lateral compartment as increasingly valgus osteotomies were simulated. The models demonstrated a consistent “safe zone” for weight bearing line position at 50%-65% medial-lateral tibial width, outside of which compartment stresses and pressures substantial increased.

This study suggests a safe correction zone within which a medial opening wedge HTO can be performed correcting the WBL to 55% medio-lateral width of the tibia.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_7 | Pages 11 - 11
1 May 2018
Alvand A Grammatopoulos G Quiney F Taylor A Whitwell D Price A Dodd C Jackson W Gibbons M
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Endoprosthetic replacement (EPR) is an available option for the management of massive bone loss around failed knee implants. The aim of this study was to determine the results of knee EPRs performed for non-tumour indications. Since 2007, 85 EPRs were performed for in a single tertiary centre by seven surgeons. Mean age at surgery was 73.5 years (range:35–95) with infection as the most common indication (49%), followed by aseptic loosening (18%), complex primary replacement (16%), fracture (15%) and mechanical failure (2%). Mean follow up was 4 years (range:1–9). Functional outcome was determined using the Oxford Knee Score (OKS). At follow-up, 21 patients were deceased and 2 lost to follow-up. Complication rate was 19%. Of the 7 infected cases, 6 were treated with DAIR (debridement, antibiotics, and implant retention) and one underwent above knee amputation. Four of the patients undergoing DAIR were cleared of infection and 2 are on long-term antibiotics. Accounting for implant revision, loss to follow-up and those on long-term antibiotics as failures, 5-year survival was 89% with an average OKS of 25 (SD=10). This mid-term study shows that distal femur EPR is a valuable option for the increasing burden of complex revision knee surgery


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_9 | Pages 12 - 12
1 May 2017
Gibbs V Wall P Sprowson A Hutchinson C Ngandwe E Price A
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Background

Traditionally, a Surgical Tourniquet (ST) is used during Total Knee Replacement Surgery (TKRS) to prevent blood flow to the leg and improve the surgical field of view. The use of a ST is known to increase the risk of venous thromboembolism. Echogenic material, suggestive of emboli has been observed in the brain following ST deflation in TKRS despite the absence of a patent foramen ovale, likely through pulmonary shunts. The aim of this study was to assess whether cerebral emboli result from tourniquet use in TKRS and the sequelae of any emboli.

Methods

11 subjects from a single centre undergoing routine TKRS with a ST gave informed consent. Each participant had diffusion weighted MR brain imaging prior to, and within 48 hours after TKRS and completed pre and post-operative mini-mental state examinations (MMSE).


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_8 | Pages 82 - 82
1 Apr 2017
Palmer J Palmer A Jones L Jackson W Glyn-Jones S Price A
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Background

Since 2011, the knee service at the Nuffield Orthopaedic Centre has been offering a neutralising medial opening wedge high tibial osteotomy (HTO) to a group of patients presenting with early medial osteoarthritis of the knee, varus alignment and symptoms for more than 2 years. During development of this practice an association was observed between this phenotype of osteoarthritis and the presence of CAM deformity at the hip.

Methods

A retrospective cohort study. All patients who underwent HTO since 2011 were identified (n=30). Comparator groups were used in order to establish whether meaningful observations were being made: Control group: The spouses of a high-risk osteoarthritis cohort recruited for a different study at our unit (n=20) Pre-arthroplasty group: Patients who have undergone uni-compartmental arthroplasty (UKA) for antero-medial osteoarthritis (n=20)All patients had standing bilateral full-length radiographs available for analysis using in house developed Matlab-based software for hip measurements and MediCAD for lower limb alignment measurements.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_8 | Pages 96 - 96
1 Apr 2017
Sayers A Wylde V Lenguerrand E Gooberman-Hill R Dawson J Beard D Price A Blom A
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Background

This article reviews four commonly used approaches to assess patient responsiveness to a treatment or therapy [Return To Normal (RTN), Minimal Important Difference (MID), Minimal Clinically Important Difference (MCID), OMERACT-OARSI (OO)], and demonstrates how each of the methods can be formulated in a multi-level modelling (MLM) framework.

Methods

Data from the Arthroplasty Pain Experience (APEX) cohort study was used. Patients undergoing total hip and knee replacement completed the Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire prior to surgery and then at 3, 6 and 12 months after surgery. We compare baseline scores, change scores, and proportion of individuals defined as “responders” using traditional and multi-level model (MLM) approaches to patient responsiveness.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_23 | Pages 4 - 4
1 Dec 2016
Alvand A Grammatopoulos G de Vos F Scarborough M Athanasou N Kendrick B Price A Gundle R Whitwell D Jackson W Taylor A Gibbons M
Full Access

Introduction

The burden of peri-prosthetic joint infection (PJI) following hip and knee surgery is increasing. Endoprosthetic replacement (EPR) is an option for management of massive bone loss resulting from infection around failed lower limb implants.

Aims

To determine clinical outcome of EPRs for treatment of PJI around the hip and knee joint.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 339 - 339
1 Jul 2014
Snelling S Price A Carr A Le L Clark I
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Summary Statement

Dickkopf-3 is upregulated in OA cartilage and synovial tissue. In vitro studies show Dkk3 can prevent cartilage degradation and antagonise Wnt signaling. We hypothesis that Dkk3 can protect against OA-related cartilage destruction.

Introduction

Our group has previously shown that Dkk3, a member of the Dkk family of Wnt antagonists, is upregulated in OA cartilage and synovium. Levels of Dkk3 in synovial fluid are also increased in individuals with tricompartmental OA and after arthroscopy. The role of Dkk3 in cartilage or the factors regulating its expression are not currently understood. Correct regulation of cell signalling pathways is integral to cartilage homeostasis and thus the prevention of OA pathogenesis. Dkk3 is a member of the Dkk family of Wnt antagonists and therefore may impact on chondrocyte biology through interaction with the Wnt pathway. Dkk3 has also been found to influence TGFβ signalling in other cell systems.


Orthopaedic Proceedings
Vol. 96-B, Issue SUPP_11 | Pages 344 - 344
1 Jul 2014
Armengol M Brown C Hulley P Price A Gill H
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Summary

The mechanical properties of porcine tibial plateau (TP) cartilage are shown to vary topographically. Low Elastic moduli (Em) were found in the positions where unicompartimental knee osteoarthritis (OA) lesions are typically expected to develop. These results suggest that there is a different response to load in these areas.

Introduction

OA is one of the ten most disabling diseases in developed countries. OA of the knee, in particular, is a major cause of mobility impairment; up to 40% of the population over the age of 70 suffers from OA of the knee. It has been observed that unicompartmental knee OA occurs with very distinct and repeatable lesion patterns. It is hypothesised that these patterns are the result of differences in the material properties throughout articular cartilage. The aim of this study was to measure the mechanical properties of porcine cartilage in a whole undamaged TP.


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_27 | Pages 12 - 12
1 Jul 2013
Logishetty K Cope A Ferguson J Alvand A Price A Rees J
Full Access

Introduction

Current work-hour restrictions and cost pressures have highlighted the limitations of apprenticeship-based learning, and led to the development of alternative methods to improve the skills of orthopaedic trainees outside of the clinical environment. These methods include using synthetic bones and simulators in the laboratory setting. Educational theory highlights the importance of context for effective learning, yet full-immersion simulation facilities are prohibitively expensive. This study explored the concept of contextualised training day in trauma & orthopaedics.

Methods

Fifteen novice surgeons provided feedback after completing three teaching modules:

OSCE-style Problem-based Learning of Orthopaedic Trauma in the Fracture Clinic Setting, utilising an actor and radiographs to teach history, examination, diagnostic and management skills

The positioning, preparing and draping of a patient, and Examination under anaesthesia (EUA) for arthroscopic knee surgery, utilising an operating table and theatre equipment to teach procedural and examination skills

Simulator based training for diagnostic shoulder and knee arthroscopy; and Bankart repair, utilising arthroscopic stack and synthetic joint models to develop arthroscopic motor skill and procedural knowledge


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 35 - 35
1 Jan 2013
Williams D Price A Beard D Hadfield S Arden N Murray D Field R
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Objectives

This study examines variations in knee arthroplasty patient reported outcome measures according to patient age.

Methods

We analysed prospectively collected outcome data (OKS, Eq5D, satisfaction, and revision) on 2456 primary knee arthroplasty patients. Patients were stratified into defined age groups (< 55, 55–64, 65–74, 75–84, and ≥85 years). Oxford Knee Score and Eq5D were analysed pre-operatively, and postoperatively at 6 months and 2 years. Absolute scores and post-operative change in scores were calculated and compared between age groups. Satisfaction scores (0–100) were analysed at 6 months post-operatively. Linear, logistic and ordinal regression modelling was used to describe the association between age and outcomes, for continuous, binary and ordinal outcomes, respectively. Kaplan-Meier analysis was performed to describe revision rates at 2 years.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 67 - 67
1 Jan 2013
Liddle A Pandit H Jenkins C Price A Gill H Dodd C Murray D
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Unicompartmental Knee Replacement (UKR) is associated with fewer complications, faster recovery and better function than Total Knee Replacement (TKR). However, joint registries demonstrate a higher revision rate in UKR, limiting its use. Currently most UKRs are cemented and performed using a minimally invasive technique. In joint registries, common reasons for revision include aseptic loosening and pain. These problems could potentially be addressed by using cementless implants, which may provide more reliable fixation.

The objectives of this study were to compare the quality of fixation (determined by the incidence and appearance of radiolucencies), and clinical outcomes of cemented and cementless UKR at five years.

A randomised controlled trial was established with 63 knees (62 patients) randomised to either cemented (32 patients) or cementless UKR (30 patients). Fixation was assessed with fluoroscopic radiographs aligned to the bone-implant interface at one and five years. Outcome scores were collected pre-operatively and at one, two and five years, including Oxford Knee Score (OKS), American Knee Society Score, objective and functional (AKSS-O/F) and Tegner Activity Scale (TAS), expressed as absolute scores and 0–5 year change (δ) scores.

Four patients died during the study period. There were no revisions. Mean operative time was 11 minutes shorter in the cementless group (p=0.029). At five years, there was no significant difference in any outcome measure except AKSS-F and δAKSS-F which were significantly better in the cementless group (both p=0.003). There were no femoral radiolucencies in either group. There were significantly more tibial radiolucencies in the cemented group (20/30 vs 2/27, p< 0.001). There were nine complete radiolucencies in the cemented group and none in the cementless group (p< 0.001).

Cementless fixation provides improved fixation at five years compared to cemented fixation in UKR, maintaining equivalent or superior clinical outcomes with a shorter operative time and no increase in complications.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 96 - 96
1 Jan 2013
Palmer A Thomas G Whitwell D Taylor A Murray D Price A Arden N Glyn-Jones S
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Introduction

Hip arthroscopy is a relatively new procedure and evidence to support its use remains limited. Well-designed prospective clinical trials with long-term outcomes are required, but study design requires an understanding of current practice. Our aim was to determine temporal trends in the uptake of non-arthroplasty hip surgery in England between 2001 and 2011.

Methods

Using procedure and diagnosis codes, we interrogated the Hospital Episode Statistics (HES) Database for all hip procedures performed between 2001 and 2011, excluding those relating to arthroplasty, tumour or infection. Osteotomy procedures were also excluded.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 199 - 199
1 Jan 2013
Alvand A Khan T Al-Ali S Jackson W Price A Rees J
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Introduction

Restrictions placed on the working hours of doctors have led to increasing time-pressures on surgical training. Consequently, there has been growing interest in developing new techniques to teach and assess technical skills. The primary aim of this study was to determine whether a novel set of visual parameters assessing visuospatial ability, fine motor dexterity and gaze control could objectively distinguish between varying levels of arthroscopic experience. The secondary aim was to evaluate the correlations between these new parameters and previously established technical skill assessment methods.

Methods

27 subjects were divided into a “novice” group (n=7), “trainee” group (n=15) and expert group (n=5) based on previous arthroscopic experience. All subjects performed a diagnostic knee arthroscopy task on a simulator. Their performance was assessed using new simple visual parameters that included “prevalence of instrument loss,” “triangulation time” and “prevalence of look downs”. In addition, performance was also evaluated using previously validated technical skill assessment methods (a global rating scale and motion analysis).


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 66 - 66
1 Jan 2013
Liddle A Pandit H Jenkins C Price A Dodd C Gill H Murray D
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Indications for Unicompartmental Knee Arthroplasty (UKA) vary between units. Some authors have suggested, and many surgeons believe, that medial UKA should only be performed in patients who localise their pain to the medial joint line. This is despite research showing a poor correlation between patient-reported location of pain and radiological or operative findings in osteoarthritis. The aim of this study is to determine the effect of patient-reported pre-operative pain location and functional outcome of UKA at one and five years.

Pre-operative pain location data were collected for 406 knees (380 patients) undergoing Oxford medial UKA. Oxford Knee Score, American Knee Society Scores and Tegner activity scale were recorded preoperatively and at follow-up. 272/406 (67%) had pure medial pain, 25/406 (6%) had pure anterior knee pain and 109/406 (27%) had mixed or generalised pain. None had pure lateral pain. The primary outcome interval is one year; 132/406 patients had attained five years by the time of analysis and their five year data is presented.

At one and five years, each group had improved significantly by each measure (mean δOKS 15.6 (SD 8.9) at year one, 16.3 (9.3) at year five). There was no difference between the groups, nor between patients with and without anterior knee pain or isolated medial pain.

We have found no correlation between preoperative pain location and outcome. We conclude that localised medial pain should not be a prerequisite to UKA and that it may be performed in patients with generalised or anterior knee pain.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 198 - 198
1 Jan 2013
Alvand A Jackson W Khan T Middleton R Gill H Price A Rees J
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Introduction

Motion analysis is a validated method of assessing technical dexterity within surgical skills centers. A more accessible and cost-effective method of skills assessment is to use a global rating scale (GRS). We aimed to perform a validation experiment to compare an arthroscopic GRS against motion analysis for monitoring orthopaedic trainees learning simulated arthroscopic meniscal repairs.

Methods

An arthroscopic meniscal repair task on a knee simulator was set up in a bioskills laboratory. Nineteen orthopaedic trainees with no experience of meniscal repair were recruited and their performance assessed whilst undertaking a standardized meniscal repair on 12 occasions. An arthroscopic GRS, assessing parameters such as “depth perception,” “bimanual dexterity,” “instrument handling,” and “final product analysis” was used to evaluate technical skill. Performance was assessed blindly by watching video recordings of the arthroscopic tasks. Dexterity analysis was performed using a motion analysis tracking system which measured “time taken,” “total path length of the subject's hands,” and “number of hand movements”.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 315 - 315
1 Sep 2012
Pemoff A Alegri C Sicardi M Blanchetiere H Balan S Gitard M Douglas Price A Caviglia H
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INTRODUCTION

Musicians' hand problems are as old as music itself. These problems involve functional motor disorders which have been underestimated by musicians, who do not want to accept the possibility of reducing their professional activity and doctors who are either not knowledgeable about musicians' characteristics or underestimate this artistic activity.

The aim of this study is to determine the causes of the pathologies instrumentalist musicians have, and their distribution according to age group, instrument and type of music, and thus infer the main risk factors in the occurrence of medical problems related to musicians' activity.

MATERIALS AND METHODS

We consider musicians those who devote themselves to the study, teaching and playing of a musical instrument. In Argentina there are about 50.000 instrumental musicians.

Since over 14 years the members of “Las Manos del Músico” have treated 574 musicians. The 84% of the medical problems related to the playing of the instrument. Ages are between 13 and 78 years.

The musicians treated belong to different conservatories, symphonic and popular orchestras. Each musician was studied with the same protocol, filled in by the same professional.

Variables such as type of music, age, sex, instrument, dominance andrelated variables were taken into account.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 133 - 133
1 Sep 2012
Weston-Simons J Pandit H Haliker V Price A Dodd C Popat M Murray D
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Introduction

The peri-operative analgesic management of patients having either Total Knee Replacement (TKR) or Unicompartmental Knee Replacement (UKR) is an area that continues to have prominence, driven in part by the desire to reduce hospital stay, while maintaining high patient satisfaction. This is particularly relevant in the current climate of healthcare cost savings. We evaluated the role of “top up” intra-articular local anaesthetic injection after identifying that an appreciable number of patients in the unit suffered “breakthrough pain” on the first post-op day, when the effects of local analgesia are wearing off.

Method

43 patients, who were scheduled to have a cemented Oxford UKR, were prospectively recruited and randomised. All patients had the same initial anaesthetic regime of general anaesthesia, femoral nerve block and intra-operative intra-articular infiltration of the cocktail. All patients had a 16G multi-holed epidural catheter placed intra-articularly prior to wound closure. Patients had the same operative technique, post operative rehabilitation and rescue analgesia.

An independent observer recorded post-operative pain scores using a visual analogue score (1–10) every 6 hours and any rescue analgesia that was required. On the morning after surgery, 22 patients, (Group I), received 20 mls of 0.5% bupivicaine through the catheter whilst 21 patients, (Group II), had 20 mls of normal saline by the same observer, (who was blinded to the contents of the solution being injected), after which the catheter was removed.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 42 - 42
1 Sep 2012
Douglas Price A Cuestas N Cambiaggi G Vazquez M Caviglia H
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Objective

To assess the beneficial use of polypropylene mesh impregnated with vancomycin in an experimental model open fractures Gustilo IIIa in rabbits.

Material and Method

We worked with 15 New Zeland White rabbits. All of them were carried out under general anaesthetic, a 5-cm incision longitudinal was made at the back of the right thigh. The femur was aproached and a fracture was performed with a shear, giving rise to a multifragment fracture. The wound remained open for 6 hours with the bone exposed, in a non-surgical ambient. Subsequently underwent surgical cleaning of the open fractures in two stages. The fracture was stabilized with an intramedular pin. The animals were sorted in 3 different therapeutic groups:

Group 1: (5 rabbits) without other treatment.

Group 2: (5 rabbits) a polypropylene mesh was placed around the fracture.

Group 3: (5 rabbits) a polypropylene mesh with vancomycin was placed around the fracture.

The wound was closed with nylon stiches.

Three weeks postoperative, the animals were intervened surgically under general anesthesia, after aseptic cure and placement of surgical fields, femoral bone biopsies, soft tissue and mesh were taken. The rabbits were sacrified. The samples were sent to pathology and bacteriology labs.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXIX | Pages 241 - 241
1 Sep 2012
Khan T Jackson W Beard D Ahmad M Spacie R Jones R Barker K Price A
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Background

Despite interest, the current rate of day-case anterior cruciate ligament reconstruction (ACLR) in the UK remains low. Although specialised care pathways with standard operating procedures (SOPs) have been effective in reducing length of stay following some surgical procedures, this has not been previously reported for ACLR. We evaluate the effectiveness of SOPs for establishing day-case ACLR in a specialist unit.

Methods

Fifty patients undergoing ACLR between May and September 2010 were studied prospectively (“study group”). SOPs were designed for pre-operative assessment, anaesthesia, surgical procedure, mobilisation and discharge. We evaluated length of stay, readmission rates, patient satisfaction and compliance to SOPs. A retrospective analysis of 50 patients who underwent ACLR prior to implementation of the day-case pathway was performed (“standard practice group”).


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXIX | Pages 213 - 213
1 Sep 2012
Ashmore A Beard D Price A Gill H
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Aims

Interest in soft tissue Radiostereometric Analysis (RSA) is rising. Previous authors have tried, with varying levels of success, to use this technique to analyse the intra-substance portion of anterior cruciate ligament (ACL) graft constructs. These methods were either prone to large amounts of marker migration, deemed unsuitable for in-vivo use or, where alternative markers such as stainless steel sutures were used, lost the inherent accuracy that made RSA an attractive tool in the first place. We describe a modification of tantalum marker balls that allows for a new method of secure fixation to soft tissue in order to accurately analyse stretch, displacement and, potentially, dynamic movement using RSA.

Methods

1.5 mm tantalum tendon markers were predrilled with 0.3 mm holes, allowing them to be sutured directly to soft tissue. Using a previously described ACL graft model, the amount of marker ball migration was then analysed using RSA after cyclical loading between 20 N and 170 N at 25 Hz for 225,000 cycles.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 43 - 43
1 Sep 2012
Douglas Price A Blanchetiere H Pemoff P Cuestas N Caviglia H
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Introduction

Monomicrobian necrotizing cellulitis affects the skin and subcutaneous tissue as starting point the deepest level of the superficial fascia. The pathogen inoculation is by skin disruption, abrasions, burns, injections or bites. The free base cocaine is used with homemade pipes that generate pulps fingers skin microabrasions. We present 3 patients (one bilateral) with cellulitis necrotizing of the thumb caused by pricking and dermoabrasive trauma secondary to different manipulation methods for drogue use.

Material and Method

Experience in 3 patients free base cocaine addicts treated in our Hospital. Medical examination shows febrile syndrome (corporal temperature over 38C), and elevation of heart rate. They present cellulitis in thumb's first and second phalanx, with thenar swelling and digital necrosis with abundant purulent discharged. All of them had a pricking trauma 36 to 48 hours before. They were under surgical intervention, by surgical cleaning with necrotic and devitalized tissue's debridement. In 3 of the 4 patients amputation of the distal phalanx was mandatory. Tissue and bone culture was made in all patients. Intravenous antibiotic was performed. Two patients miss total antibiotic treatment by early no medical discharged.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 422 - 422
1 Sep 2012
Weston-Simons J Pandit H Kendrick B Beard D Gibbons M Jackson W Gill H Price A Dodd C Murray D
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Introduction

The options for the treatment of the young active patient with unicompartmental symptomatic osteoarthritis and pre-existing Anterior Cruciate Ligament (ACL) deficiency are limited. Patients with ACL deficiency and end-stage medial compartment osteoarthritis are usually young and active. The Oxford Unicompartmental Knee Replacement (UKA) is a well established treatment option in the management of symptomatic end-stage medial compartmental osteoarthritis, but a functionally intact ACL is a pre-requisite for its satisfactory outcome. If absent, high failure rates have been reported, primarily due to tibial loosening. Previously, we have reported results on a consecutive series of 15 such patients in whom the ACL was reconstructed and patients underwent a staged or simultaneous UKA. The aim of the current study is to provide an update on the clinical and radiological outcomes of a large, consecutive cohort of patients with ACL reconstruction and UKA for the treatment of end-stage medial compartment osteoarthritis and to evaluate, particularly, the outcome of those patients under 50.

Methods

This study presents a consecutive series of 52 patients with ACL reconstruction and Oxford UKA performed over the past 10 years (mean follow-up 3.4 years). The mean age was 51 years (range: 36–67). Procedures were either carried out as Simultaneous (n=34) or Staged (n=18). Changes in clinical outcomes were measured using the Oxford Knee Score (OKS), the change in OKS (OKS=Post-op − Pre-op) and the American Knee Society Score (AKSS). Fluoroscopy assisted radiographs were taken at each review to assess for evidence of loosening, radiolucency progression, (if present), and component subsidence.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 249 - 249
1 Sep 2012
Kendrick B Weston-Simons J Sim F Gibbons M Pandit H Gill H Price A Dodd C Murray D
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Introduction

Radiolucencies beneath the tibial component are well recognized in knee arthroplasty; the aetiology and significance are poorly understood. Non-progressive narrow radiolucencies with a sclerotic margin are thought not to be indicative of loosening. Factors which decrease the incidence of radiolucencies include cementless fixation and the use of pulse lavage. Leg/component alignment or BMI do not influence radiolucency. We are not aware of any studies that have looked at the effect of load type on radiolucency.

The Oxford domed lateral tibial component was introduced to decrease the bearing dislocation rate that was unacceptably high with the flat tibial tray. However, the introduction of the domed tibial component alters the forces transmitted through the implant-cement-bone interface. As the Oxford UKR uses a fully congruent mobile bearing, the forces transmitted through the interface with a flat tray are compressive, except for the effect of friction. However, with the domed tibial component shear forces are introduced. The aim of this study was to assess the prevalence of radiolucency beneath the previous flat design and the new domed tibial tray.

Patients and methods

A consecutive series of 248 cemented lateral UKRs (1999–2009) at a single institution were assessed. The first 55 were with a flat tibia and the subsequent 193 with a domed component. One year post-op radiographs were assessed, by two observers, for the presence (full or partial) and distribution of radiolucency. The distribution and thickness of each radiolucency. Cases were excluded for missing or poorly aligned radiographs.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 92 - 92
1 Jul 2012
Mehmood S Batta V Gulati A Pandit H Bottomley N Gil H Beard D Dodd C Jackson W Murray D Price A
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INTRODUCTION

Establishing a full-thickness cartilage in the lateral compartment and functionally intact ACL is vital before proceeding with unicompartmental knee replacement (UKR). The aim of this study is to assess whether MRI is a useful adjunct in predicting suitability for UKR, as compared to standard and stress radiographs.

METHODS

We identified 50 patients with a knee found suitable for UKR based on their standard and stress radiographs (full-thickness cartilage on lateral side). These patients underwent an additional cartilage-specific MRI scan to identify the status of ACL and the lateral compartment. The final decision regarding the suitability for UKR was based on the intra-operative observation.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 71 - 71
1 Jul 2012
Beard D Holt M Mullins M Massa E Malek S Price A
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Purpose

Late stage medial unicompartmental osteoarthritic disease of the knee can be treated by either Total Knee Replacement (TKR) or Unicompartmental Replacement (UKR). As a precursor to the TOPKAT study this work tested the postulate that individual surgeons show high variation in the choice of treatment for individual patients.

Method

Four surgeons representing four different levels of expertise or familiarity with partial knee replacement (UKR design centre knee surgeon, specialist knee surgeon, arthroplasty surgeon and a year six trainee) made a forced choice decision of whether they would perform a TKR or UKR based on the same pre-operative radiographic and clinical data in 140 individual patients. Consistency of decision was also evaluated for each surgeon 3 months later and the effect of additional clinical data was also evaluated. The sample consisted of the 100 patients who had subsequently undergone UKR and 40 who had undergone TKR.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 107 - 107
1 Jul 2012
Williams D Beard D Arden N Field R Price A
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Purpose

To examine the clinical characteristics of patients undergoing knee arthroplasty with a pre-operative Oxford Knee Score >34 (‘good’/‘excellent’), and assess the appropriateness of surgical intervention for this group.

Background

In the current cost-constrained health economy, justification of surgical intervention is increasingly sought. As a validated disease-specific outcome measure, the pre-operative Oxford Knee Score (OKS) has been suggested as a possible threshold measurement in knee arthroplasty. However, contrary to expectations, analysis of pre-operative OKS in the joint registry population demonstrates a normal distribution curve with a sub-group of high-scoring patients. This suggests that either the baseline OKS does not accurately define surgical threshold, or that patients with a high OKS are inappropriately having knee replacements.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 43 - 43
1 Jul 2012
Price A Jackson W Field R Judge A Carr A Arden N Murray D Dawson J Beard D
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Purpose

The Oxford Knee Score (OKS) is a validated and widely used PROM that has been successfully used in assessing the outcome of knee arthroplasty (KA). It has been adopted as the nationally agreed outcome measure for this procedure and is now routinely collected. Increasingly, it is being used on an individual patient basis as a pre-operative measure of osteoarthritis and the need for joint replacement, despite not being validated for this use. The aim of this paper is to present evidence that challenges this new role for the OKS.

Method

We have analysed pre-operative and post-operative OKS data from 3 large cohorts all undergoing KA, totalling over 3000 patients. In addition we have correlated the OKS to patient satisfaction scores. We have validated our findings using data published from the UK NJR.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 64 - 64
1 Jul 2012
Al-Ali S Khan T Jackson W Beard D Price A
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Purpose

The purpose was to determine if the use of cold irrigation fluid in routine knee arthroscopy leads to a reduction in post operative pain.

Background

Some surgeons use cooled irrigation fluid in knee arthroscopy in the hope that it may lead to a reduction in post operative pain and swelling. There is currently no evidence for this, although there is some evidence to support the use of cold therapy post operatively in knee surgery.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXIX | Pages 70 - 70
1 Jul 2012
Erturan G Neely J Richards N Price A Jackson W Khan T
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A feasibility study of the use of an MRI based patient specific knee arthroplasty system within the NHS.

Introducing new technologies within a public funded health system can be challenging. We assess the use and potential benefit of customised jigs for knee arthroplasty. Outcomes assessed were safety and accuracy of implantation.

Eight knee replacements using custom jigs were compared to 11 conventionally instrumented replacements matched to surgeon and operative day. Parameters measured include tourniquet time; drain output; hospital stay; adjusted change in haemoglobin; complications; and component position on post-operative long-leg alignment films

None of the parameters observed demonstrated a statistically significant difference from the conventional arthroplasty group. No complications were seen in either group. No significant differences were seen in alignment.

Our early experiences show that this technology appears safe and allows accurate implantation of the prosthesis. There was a trend for decreased stay and blood loss. The health economic benefits of navigational arthroplasty have been demonstrated in other studies and come from the lack of instrumentation of the intramedullary canal. MRI based patient specific instrumentation is considered technically easier and more convenient than intra-operative navigation. A larger study is planned to assess the health economic implications of adopting this new technology.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XVIII | Pages 47 - 47
1 May 2012
Bottomley N McNally E Jones L Javaid M Arden N Gill H Dodd C Murray D Beard D Price A
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Introduction

Anteromedial osteoarthritis of the knee (anteromedial gonarthrosis-AMG) is a common form of knee arthritis. In a clinical setting, knee arthritis has always been assessed by plain radiography in conjunction with pain and function assessments. Whilst this is useful for surgical decision making in bone on bone arthritis, plain radiography gives no insight to the earlier stages of disease. In a recent study 82% of patients with painful arthritis had only partial thickness joint space loss on plain radiography. These patients are managed with various surgical treatments; injection, arthroscopy, osteotomy and arthroplasty with varying results. We believe these varying results are in part due to these patients being at different stages of disease, which will respond differently to different treatments. However radiography cannot delineate these stages. We describe the Magnetic Resonance Imaging (MRI) findings of this partial thickness AMG as a way of understanding these earlier stages of the disease.

Method

46 subjects with symptomatic partial thickness AMG underwent MRI assessment with dedicated 3 Tesla sequences. All joint compartments were scored for both partial and full thickness cartilage lesions, osteophytes and bone marrow lesions (BML). Both menisci were assessed for extrusion and tear. Anterior cruciate ligament (ACL) integrity was also assessed. Osteophytes were graded on a four point scale in the intercondylar notch and the lateral margins of the joint compartments. Scoring was performed by a consultant radiologist and clinical research fellow using a validated MRI atlas with consensus reached for disagreements. The results were tabulated and relationships of the interval data assessed with linear by linear Chi2 test and Pearson's Correlation.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XVIII | Pages 24 - 24
1 May 2012
Bottomley N Javaid M Gill H Dodd C Murray D Beard D Price A
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Introduction

Anteromedial gonarthrosis is a common well described pattern of knee osteoarthritis with cartilage wear beginning in the anteromedial quadrant of the medial tibial plateau in the presence of an intact and functioning ACL. It is well known that mechanical factors such as limb alignment and meniscal integrity affect the progression of arthritis and there is some evidence that the morphology of the tibial plateau may be a risk factor in the development of this disease. The extension facet angle is the angle of the downslope of the anterior portion of the medial tibial plateau joint surface in relation to the middle portion on a sagittal view. If this is an important factor in the development of AMG there may be potential for disease modifying intervention.

This study investigates if there is a significant difference in this angle as measured on MRI between a study cohort with early AMG (partial thickness cartilage damage and intact ACL) and a comparator control cohort of patients (no cartilage damage and ACL rupture).

Methods

3 Tesla MRI scans of 99 patients; 54 with partial thickness cartilage damage and 44 comparitors with no cartilage damage (acute ACL rupture) were assessed. The extension facet angle was measured (Osirix v3.6) using a validated technique on two consecutive MRI T2 sagittal slices orientated at the mid-coronal point of the medial femoral condyle. (InterClass Correlation 0.95, IntraClass Correlation 0.97, within subject variation of 1.1° and coefficient of variation 10.7%). The mean of the two extension angle values was used. The results were tabulated and analysed (R v2.9.1).


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 25 - 25
1 Mar 2012
Pandit H Jenkins C Gill H Beard D Price A Dodd C Murray D
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Introduction

The results of the mobile bearing Oxford unicompartmental knee replacement (UKR) in the lateral compartment have been disappointing with a five year survival of 82%. Therefore, it is recommended that mobile bearings should not be used for lateral UKR. This low survivorship is primarily due to high dislocation rate, all occurring in the first year. A detailed analysis of the causes of bearing dislocation confirmed the elevated lateral tibial joint line to be a contributory factor. A new surgical technique was therefore introduced in which care was taken neither to remove too much bone from distal femur nor to over tighten the knee and thus ensure that the tibial joint line was not elevated. Other modifications to the technique were also introduced including use of a domed tibial component.

Aim

The aim of this study is to compare the outcome of these iterations: the original series [series I], Series II with improved surgical technique and the domed tibial component [Series III].


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 19 - 19
1 Mar 2012
Bottomley N Kendrick B Ferguson J Al-Ali S Dodd C Murray D Beard D Price A
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Introduction

Total knee arthroplasty (TKA) accounts for 84% of all knee replacement surgery in the UK (NJR 2009) despite published epidemiological data showing that single compartment disease is most prevalent. We investigated this incompatibility further by describing the compartmental pattern and stage of cartilage loss of all patients with osteoarthritis (OA) presenting to a specialist knee clinic over one year.

Methods

All new primary referrals in a calendar year by local General Practitioners to knee clinic at a United Kingdom Hospital were assessed. Tertiary referrals and second opinions were excluded. The final diagnosis after all imaging was recorded and tabulated. The standing AP, lateral and skyline radiographs of all cases of arthritis were scored to assess the pattern of disease.


Bone & Joint Research
Vol. 1, Issue 3 | Pages 36 - 41
1 Mar 2012
Franklin SL Jayadev C Poulsen R Hulley P Price A

Objectives

Surgical marking during tendon surgery is often used for technical and teaching purposes. This study investigates the effect of a gentian violet ink marker pen, a common surgical marker, on the viability of the tissue and cells of tendon.

Methods

In vitro cell and tissue methods were used to test the viability of human hamstring explants and the migrating tenocytes in the presence of the gentian violet ink.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 32 - 32
1 Mar 2012
Kendrick B Simpson D Bottomley N Kaptein B Garling E Gill H Dodd C Murray D Price A
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Purpose of study

To investigate the linear penetration rate of the polyethylene bearing in unicompartmental knee arthroplasty at twenty years.

Introduction

The Phase 1 Oxford medial UKR was introduced in 1978 as a design against wear, with a fully congruous articulation. In 1987 the Phase 2 implant was introduced with new instrumentation and changes to the bearing shape. We have previously shown a linear penetration rate (LPR) of 0.02 mm/year at ten years in Phase 2, but that higher penetration rates can be seen with impingement. The aim of this study was to determine the 20 year in-vivo LPR of the Oxford UKR, using Roentgen Stereophotogrammetric Analysis (RSA).


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 34 - 34
1 Mar 2012
Ferguson J Pandit H Price A Marks B Gill H Murray D Dodd C
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Introduction

Obesity has been considered a relative contra-indication in unicompartmental knee arthroplasty (UKA) due to fear of high wear rates, loosening and tibial collapse. The aim of this study was to investigate the impact of high body mass index (BMI) on ten-year survivorship and five-year functional outcome after Oxford UKA, a fully congruous mobile bearing design with large contact area and low wear rate.

Methods

This prospective study examines a consecutive series of 595 knees (mean age 66 years, range: 33-88) undergoing Oxford UKA with a minimum 5-year follow-up. Patients were divided into three groups; Group I (Normal body weight), BMI <25 (n=171), Group II (overweight), BMI 25- 30 (n=264), and Group III (Obese), BMI ≥30 (n=160). The survivorship and functional outcome (as assessed by change in Oxford Knee Score [DeltaOKS]) and Knee Society Score (KSS) for all three groups were compared.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IV | Pages 56 - 56
1 Mar 2012
Howells N Price A Carr A Rees J
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Objective

To investigate the effect of lab-based simulator training, on the ability of surgical trainees to perform diagnostic knee arthroscopy.

Method

20 orthopaedic SHOs with minimal arthroscopic experience were randomised to 2 groups. 10 received a fixed protocol of simulator based arthroscopic skills training using a bench-top knee model. Learning curves were clearly demonstrated using motion analysis equipment to monitor performance. All 20 then spent an operating list with a blinded consultant trainer. They received instruction and demonstration of diagnostic knee arthroscopy before performing the procedure independently. Their performance was assessed using the intra-operative section of the Orthopaedic Competence Assessment Project (OCAP) procedure based assessment (PBA) protocol for diagnostic arthroscopy. Performance was further quantified with a ten point global rating assessment scale.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 31 - 31
1 Mar 2012
Kendrick B Pandit H Jenkins C Beard D Gill H Price A Dodd C Murray D
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Purpose of Study

To assess the incidence of radiolucency in cemented and cementless Oxford unicompartmental knee replacement at two years.

Introduction

Most unicompartmental knee replacements (UKRs) employ cement for fixation of the prosthetic components. The information in the literature about the relative merits of cemented and cementless UKR is contradictory, with some favouring cementless fixation and others favouring cemented fixation. In addition, there is concern about the radiolucency that frequently develops beneath the tibial component with cemented fixation. The exact cause of the occurrence of radiolucency is unknown but it has been hypothesised that it may suggest suboptimal fixation.


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 27 - 27
1 Mar 2012
Pandit H Jenkins C Weston-Simons S Ferguson J Popat BM Gibbons M Price A Gill H Dodd C Murray D
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Introduction

Kozinn and Scott have made recommendations about contra-indications for unicompartmental knee replacement (UKR). They suggest that patients younger than 60, weight > 82 kilograms, patients with exposed bone in patella-femoral compartment or patients who are physically active/perform heavy labour should not be offered a UKR. In addition, chondrocalcinosis is a contra-indication. These strict selection criteria are based on the experience with fixed bearing UKAs and are more intuitive than evidence based. The Oxford UKR has a fully congruous mobile bearing and has been shown to have minimal wear. Over the past 25 years, the Oxford Group has followed a standardised protocol for patient selection for UKR. We ignore patella-femoral joint pathology, chondrocalcinosis, patient's age, weight and activity level when deciding the suitability for UKR.

Methods

Using the standardised indications, more than 1100 Oxford UKRs have been performed to date over the last 10 years. These patients are assessed pre-operatively and at regular intervals post-operatively in a dedicated research clinic. We present the results of these consecutive cases. Patients were classified into two groups: group I (satisfy Kozinn-Scott recommendations) and group II (outside recommendations).


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_IX | Pages 77 - 77
1 Mar 2012
James AR Dean B Moore E Whitwell D Price A Gibbons C
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Aim

A case series with functional and radiographic outcomes, of modular endoprosthetic distal femoral replacement in complex cases of periprosthetic fracture.

Method

Sixteen cases were identified of endoprosthetic replacement (EPR) from the bone and soft tissue cancer implant registry. A retrospective review was undertaken.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_III | Pages 315 - 315
1 Jul 2011
James A Dean B Matthews J Price A Stubbs D Whitwell D Gibbons M
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Introduction: Although originally designed to aid the management of primary malignant bone tumours, the indications for modular endoprosthetic replacement (EPR) have expanded to include complex periprosthetic fractures and failed internal fixation. The incidence of these challenging cases is increasing with an aged population. We reviewed retrospectively our experience with the use of EPR in patients who had undergone limb salvage following complex trauma presentations.

Methods: Between 2003 and 2008 twenty one patients presented with complex trauma related problems and underwent EPR at a specialist tertiary referral centre. The mean age was 71 years (range 44–87) and the median number of previous surgical procedures was 3 (range 0–11). Eight patients presented following failed internal fixation of proximal femoral fractures. Nine patients had periprosthetic fractures around joint arthroplasties, seven relating to total knee replacements (TKRs) and two to total hip replacements (THRs). One case of periprosthetic fracture around THR had undergone failed internal fixation. Two patients had distal femoral fractures, of which one was infected and had undergone failed internal fixation, while the other was unrecon-structable. Two patients had proximal tibia fractures which had both undergone failed internal fixation.

Results: The mean Harris Hip Score was 89.5 (range 64–85) at a mean follow up period of 8 months (minimum 4 months). The mean American Knee Society Score was 82 (range 62–100) and the mean functional score was 62 (range 30–75) at a mean follow up period of 6 months (minimum 2 months). Complications included two cases of deep infection; one resulted in a two stage revision procedure, while the other retained the EPR following a washout.

Discussion: Modular EPR in the lower limb is a durable reconstructive option in complex trauma problems, particularly in the elderly and those patients with significant bone loss. Preliminary functional results indicate very satisfactory results.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 208 - 208
1 May 2011
Kendrick B Simpson D Gill H Valstar E Kaptein B Dodd C Murray D Price A
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Introduction: Approximately 20% of unicompartmental knee replacement (UKR) revisions are related to polyethylene wear. The Phase 1 Oxford UKR was introduced as a design against wear, with a fully congruent mobile bearing. The Phase 2 implant was introduced with new instrumentation (femoral mill) and changes to the bearing shape (lower anterior wall) to reduce the incidence of anterior impingement. We have previously shown that the Oxford UKR has a wear rate of 0.02 mm/year at ten years, in well functioning devices, but that higher wear rates can be seen with impingement or if the congruous articulation is lost. The aim of this study was to determine the 20 year in-vivo wear of the Oxford Phase 1 and Phase 2 UKR, using Roentgen Stereophotogrammetric Analysis (RSA).

Method: We measured the in-vivo wear of 6 Phase 1 (5 patients, mean age 65.24 years) and 7 Phase 2 (4 patients, mean age 63.43) Oxford UKR bearings. Average time since surgery was 22.37 years and 19.46 years for the Phase 1 and Phase 2 implants respectively. Selection criteria included patients who were mobile, with an exercise tolerance greater than 100m as per the American Knee Society Score (AKSS) functional questionnaire. RSA x-rays were taken with the knee in the normal anatomical position on standing and with the knee flexed to 30o. The Oxford knee score (OKS) and AKSS were gained at the RSA examination. Phase 1 and 2 components were reverse engineered by laser scanning, and converted to CAD models. The CAD models of the tibia and femur were pose-estimated in the RSA software (Medis Specials, Leiden, Netherlands). A sphere was fit to the femoral component and the minimum bearing thickness was determined by measuring the shortest perpendicular distance between the sphere and the plane contained on the tibial tray articular surface. The linear wear for each bearing was calculated by subtracting the measured thickness from the corrected nominal bearing thickness. Non-parametric statistics were used to compare the two Phases.

Results: There was no significant difference in age, OKS and AKSS between the two groups. The median wear rate was 0.078 mm/year for Phase 1 and 0.023 mm/year for Phase 2. This difference was statistically significant (p = 0.027).

Discussion: The difference in wear rate is explained by impingement in Phase 1, which was reduced by design changes with the introduction of Phase 2; the Phase 2 is designed to avoid impingement between the femur and the bearing. This study demonstrates that very low wear rates can be maintained with the Phase 2 implant to the end of the second decade after implantation. This is of particular importance when the device is used in younger patients and demonstrates that the Oxford UKR can be a definitive implant for the treatment of isolated compartmental osteoarthritis.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 96 - 96
1 May 2011
Bottomley N Javaid M Judge A Gill H Murray D Beard D Price A
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Introduction: Anteromedial gonarthrosis is a common well described pattern of knee osteoarthritis with cartilage wear beginning in the anteromedial quadrant of the medial tibial plateau in the presence of an intact and functioning ACL. It is well known that mechanical factors such as limb alignment and meniscal integrity affect the progression of arthritis and there is some evidence that the morphology of the tibial plateau may be a risk factor in the development of this disease. The extension facet angle is the angle of the downslope of the anterior portion of the medial tibial plateau joint surface in relation to the middle portion on a sagittal view. If this is an important factor in the development of AMG there may be potential for disease modifying intervention.

This study investigates if there is a significant difference in this angle as measured on MRI between a study cohort with early AMG (partial thickness cartilage damage and intact ACL) and a comparator control cohort of patients (no cartilage damage and ACL rupture).

Methods: 3 Tesla MRI scans of 99 patients; 54 with partial thickness cartilage damage and 44 comparitors with no cartilage damage (acute ACL rupture) were assessed. The extension facet angle was measured (Osirix v3.6) using a validated technique on two consecutive MRI T2 sagittal slices orientated at the mid-coronal point of the medial femoral condyle. (InterClass Correlation 0.95, IntraClass Correlation 0.97, within subject variation of 1.1° and coefficiant of variation 10.7%). The mean of the two extension angle values was used. The results were tabulated and analysed (R v2.9.1).

Results: Of the 99 knees, 38 were female and 61 male; 44 left knees and 55 right. The mean extension facet angle for the partial thickness group was 12.7° (SD 3.35) and for the comparator group 8.7° (SD 3.09). There was a significant difference between these 2 groups (Mann Whitney U, p< 0.001). Although there were significantly more men than women in the comparator group, stratification analysis showed that there was no effect of gender on the mean extension facet angle.

Discussion: There is a significance difference in the extension facet angle between patients with AMG with only partial thickness cartilage loss and a comparator group. This has not been shown in a study group of this size before. Since none of the subjects had full thickness cartilage loss it is unlikely that this difference is due to bone attrition changing the angle as part of the disease process but this is an important area for further study. We believe that a higher medial tibial extension facet angle alters the mechanics within the medial compartment, placing these patients at higher risk of developing AMG. This may present an opportunity for risk factor modification, for example osteotomy.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 182 - 182
1 May 2011
Simpson D Kendrick B Gill H Pandit H Dodd C Price A Murray D
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Introduction: Partial Knee Replacement (PKR) is an appealing alternative to Total Knee Replacement (TKR) when the patient has isolated compartment osteoarthritis (OA). In nearly all cases there is a radiolucency observed between the tibial tray wall and the boney interface. The reasons why radiolucencies appear are unknown, but the bone will adapt to its altered mechanical environment by bone remodelling in accordance with ‘Wollf’s Law’. The aim of this study was to investigate the mechanical environment of the tibia bone adjacent to the tray wall, following cemented and cementless PKR, in order to determine whether this region of bone resorbs.

Methods: A validated finite element (FE) model of a cadaver tibia implanted with an Oxford PKR was used in this study. Kinematic data from fluoroscopy measurements during a step-up activity were used to determine the relative tibio-femoral positioning for the Oxford PKR model. Load data were adapted from the in-vivo measured loads using an instrumented implant during a step-up activity. The standard operating protocol was simulated for the Oxford PKR FE models, with the tibial tray implanted in a neutral position. The tibia was sectioned around the tray. Zone 7 was defined as parallel to the vertical tray wall, corresponding to the region on screened x-rays where radiolucencies are observed. It was assumed that the bone in the implanted tibia will attempt to normalise its stress-strain patterns locally to its equilibrium state, the intact tibia, for the same loading conditions. Forty patients (20 cemented, 20 cementless) who had undergone PKR were randomly selected from a database, and their screened x-rays assessed for radiolucency in region 7.

Results: The SED in region 7 was 80% lower in the cemented and cementless tibia, compared to the intact tibia (Figure 2). The maximum tensile stress was 63% lower in the cemented and cementless tibia, compared to the intact tibia. The corresponding maximum compressive stress was 52% lower. Radiolucency was observed in all forty radiographs in region 7.

Discussion: After implantation with a cemented or cementless PKR the bone strains and SED in region 7 are reduced. This reduction may provide the signal for adaptive bone remodelling and bone will be resorbed from this region, decreasing the volume and increasing the SED. Bone resorption will continue until the equilibrium state is reached. If a ‘lazy’ zone between 35% and 50% of the remodelling signal is considered, bone resorption will still occur due to the large decrease in SED for this region. For region 7 to return its SED to the equilibrium state, its volume will need to be reduced by 80%. This is likely to be the reason why a radiolucency is observed clinically in this region in almost every case, whether a cemented or cementless implant is used.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_II | Pages 135 - 135
1 May 2011
Dean B Matthews J Price A Stubbs D Whitwell D Gibbons C
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Introduction: Although originally designed to aid the management of primary malignant bone tumours, the indications for modular endoprosthetic replacement (EPR) have expanded to include complex periprosthetic fractures and failed internal fixation. The objective of this study was to evaluate the success of endoprosthetic replacement (EPR) in patients who had undergone limb salvage following complex trauma presentations.

Materials and Methods: Between 2003 and 2008 twenty one patients presented with complex trauma related problems and underwent EPR at a specialist tertiary referral centre. The mean age was 71 years (range 44–87) and the median number of previous surgical procedures was 3 (range 0–11). Eight patients presented following failed internal fixation of proximal femoral fractures. Nine patients had periprosthetic fractures around joint arthroplasties, seven relating to total knee replacements (TKRs) and two to total hip replacements (THRs). One case of periprosthetic fracture around THR had undergone failed internal fixation. Two patients had distal femoral fractures, of which one was infected and had undergone failed internal fixation, while the other was unreconstruc-table. Two patients had proximal tibia fractures which had both undergone failed internal fixation.

Results: The mean Harris Hip Score was 89.5 (range 64–85) at a mean follow up period of 8 months (minimum 4 months). The mean American Knee Society Score was 82 (range 62–100) and the mean functional score was 62 (range 30–75) at a mean follow up period of 6 months (minimum 2 months). Complications included two cases of deep infection; one resulted in a two stage revision procedure, while the other retained the EPR following a washout.

Conclusion: Modular EPR in the lower limb is a durable reconstructive option in complex trauma problems, particularly in the elderly and those patients with significant bone loss. Preliminary functional results indicate very satisfactory results.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 19 - 19
1 Jan 2011
Pandit H Jenkins C Beard D Gill H Price A Dodd C Murray D
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The results of mobile bearing Oxford unicompartmental knee replacement (UKR) in the lateral compartment have been disappointing (five-year survival: 82%). Therefore, it is recommended that mobile bearings should not be used for lateral UKR. This low survivorship is primarily due to a high dislocation rate. A detailed analysis confirmed the elevated lateral tibial joint line to be a contributory factor to bearing dislocation. A new surgical technique was therefore introduced in which care was taken neither to remove too much bone from the distal femur nor to over tighten the knee and therefore ensure that the tibial joint line was not elevated. Other modifications included use of a domed tibial component.

The aim of this study is to compare the outcome of these iterations: the original series (series I), those with improved surgical technique (series II) and the domed tibial component (series III). The primary outcome measure was bearing dislocation at one year. One year was chosen as all the dislocations in the first series occurred within a year. In the original series (n=53), implanted using a standard open approach, there were six dislocations in the first year, the average flexion 110°, and 95% had no/mild pain on activity. In the second series (n=65), there were 3 dislocations, the average flexion was 117°, and 80% had no/mild pain on activity.

In the third series with the modified technique and a convex domed tibial plateau, there was one dislocation, average flexion was 125° and 94% had no/mild pain on activity. At four years the cumulative primary dislocation rates were 10%, 5% and 0% respectively, and were significantly different (p=0.04).

The improved surgical technique and implant design has reduced dislocation rate to an acceptable level so a mobile bearing can now be recommended for lateral UKR.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 19 - 19
1 Jan 2011
Pandit H Jenkins C Beard D Gill H Price A Dodd C Murray D
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About ten years ago we introduced sophisticated instrumentation and an increased range of component sizes for the Oxford unicompartmental knee replacement (UKR) to facilitate a minimally invasive surgical (MIS) approach. The device is now routinely implanted through an incision from the medial pole of the patella to the tibial tuberosity. This has resulted in a more rapid recovery and an improved functional result. As the access to the knee is limited there is a concern that the long term results may be compromised. The aim of this study was to determine the 10 year survival.

A prospective follow up of all Phase 3 minimally invasive Oxford UKR implanted by two senior authors (DWM & CAFD) has been undertaken. So far 1015 UKRs have been implanted for anteromedial osteoarthritis. All patients received a cemented implant through a MIS approach and were followed up prospectively by an independent observer. The data was collected prospectively regarding pre-operative status, complications and clinical as well as functional outcome at predetermined intervals.

The average age of patients was 66.4 years (range: 33 – 88) with mean Oxford Knee Score 41 (SD: 7.9) at the time of last follow up, Knee Society Score (objective) of 84 (SD: 13) and Knee Society Score (functional) of 83 (SD: 21). At ten years the survival of this cohort is 96%. There were 22 revisions including 7 for progression of arthritis, 5 for infection, 5 for bearing dislocation, 4 for unexplained pain and one for rupture of ACL secondary to trauma.

We conclude that the Oxford Knee can be implanted reliably through a minimally invasive approach, giving excellent long term results.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 30 - 30
1 Jan 2011
Rout R McDonnell S Hollander A Davidson R Clark I Murray D Gill H Hulley P Price A
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Our aim was to investigate the molecular features of progressive severities of cartilage damage, within the phenotype of Anteromedial Gonarthrosis (AMG).

Ten medial tibial plateau specimens were collected from patients undergoing unicompartmental knee replacements. The cartilage within the area of macroscopic damage was divided into equal thirds: T1(most damaged), to T3 (least damaged). The area of macroscopically undamaged cartilage was taken as a 4th sample, N. The specimens were prepared for histological (Safranin-O and H& E staining) and immunohistochemical analysis (Type I and II Collagen, proliferation and apoptosis). Immunoassays were undertaken for Collagens I and II and GAG content. Real time PCR compared gene expression between areas T and N.

There was a decrease in OARSI grade across the four areas, with progressively less fibrillation between areas T1, T2 and T3. Area N had an OARSI grade of 0 (normal). The GAG immunoassay showed decreased levels with increasing severity of cartilage damage (p< 0.0001). There was no significant difference in the Collagen II content or gene expression between areas. The Collagen I immunohistochemistry showed increased staining within chondrocyte pericellular areas in the undamaged region (N) and immunoassays showed that the Collagen I content of this macroscopically and histologically normal cartilage, was significantly higher than the damaged areas (p< 0.0001). Furthermore, real time PCR showed a significant increase in Collagen I expression in the macroscopically normal areas compared to the damaged areas (p=0.04).

In AMG there are distinct areas, demonstrating progressive cartilage loss. We conclude that in this phenotype the Collagen I increase, in areas of macroscopically and histologically normal cartilage, may represent very early changes of the cartilage matrix within the osteoarthritic disease process. This may be able to be used as an assay of early disease and as a therapeutic target for disease modification or treatment.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 73 - 73
1 Jan 2011
Bottomley N McNally E Ostlere S Kendrick B Murray D Dodd C Beard D Price A
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Introduction: This study explores whether modern magnetic resonance imaging (MRI) with improved cartilage sequencing is able to show a more detailed view of antero-medial osteoarthritis of the knee (AMOA) than previously, so enabling a radiographic description of this common phenotype of disease. Modern MRI technology allows us to visualize in great detail the structures and cartilage within the knee, providing a better understanding of the pathoanatomy of AMOA. This description of the end stage of disease is useful as a baseline when investigating the progression of arthritis through the knee. Preoperative assessment of patients and selection of intervention is very important and preoperative imaging forms an integral part of this. This will also be useful in preoperative assessment and surgical management of patients.

Methods: 50 patients with a radiographic diagnosis of anteromedial osteoarthritis of the knee and had been listed for unicompartmental knee arthroplasty (UKA) had MRI as part of their pre-op workup. At operation all were deemed suitable for UKA using the current Oxford indications. The image sequences were coronal, axial and sagittal with a predetermined cartilage protocol. The state of the ACL, cartilage wear degree and location, presence and pattern of osteophytes, meniscal anatomy and subchondral high signal were assessed.

Results: All the ACLs were visualized and in continuity, however 40% showed intrasubstance high signal. 100% of medial compartments showed full thickness anteromedial loss with preservation of the posteromedial cartilage. When present, the meniscus was extruded in 75% of cases.

90% of lateral compartments were normal and none had full thickness cartilage loss. However 10% showed high signal in the tibial plateau. There was a highly reproducible pattern of osteophyte formation; 94% posteromedial and posterolateral aspect of medial femoral condyle; 90% medial tibial; 80% medial femoral and 84% lateral intercondylar notch.

Discussion: This study maps the pattern of anteromedial osteoarthritis using modern MRI techniques. This creates a baseline description of disease which is useful when investigating disease progression. This also has importance in determining preoperative indications (preservation of ACL and posteromedial cartilage); surgical technique (determine pattern of osteophytes requiring resection) and potentially important for long-term outcome (early lateral compartment changes).


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_I | Pages 70 - 70
1 Jan 2011
Rout R Mcdonnell S Snelling S Xia X Bottomley N Hulley P Price A
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Introduction: Anteromedial gonarthrosis (AMG) is a distinct phenotype of osteoarthritis (OA), with a specific pattern of disease. There is full thickness cartilage loss anteromedially, progressing to an area of damaged cartilage, and then to an area of macroscopically and histologically normal cartilage posteriorly. It can be considered to be a spatial model of OA progression. Apoptosis, or chondrocyte cell death, has been shown to be a feature of OA cartilage, however the triggers are poorly understood; similarly, reactive oxygen species (ROS) have been implicated in OA. They have never been studied in a replicable topographical model of OA. This study characterises the regional levels of cell death and implicated ROS in AMG using a number of immunohistochemical studies.

Method: Ten tibial resection specimens were obtained from patients undergoing unicompartmental knee arthroplasty. Eight above knee amputations (from patients with peripheral vascular disease) were used as age matched controls. Cross sections taken through all regions were paraffin embedded. Routine histology was performed and immunohistochemical studies were conducted for Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), Active Caspase 3, Cytochrome C, Active Bax, Bim, 3-Nitrotyrosine and Forkhead Box O3A (FOXO 3A).

Results: Cell death, as detected by TUNEL appeared predominantly in the surface layer of chondrocytes of damaged cartilage (p< 0.001). Median values were 23% in superficial cartilage (range 0 – 51) compared to 0% in deeper cartilage (range 0 – 15). There was a significant difference in TUNEL staining between regions (p=0.001). This ranged from 26% (most damaged) to 4% (undamaged). There was a good correlation with degree of cartilage damage (ρ=0.66, p< 0.001) asdefined by histological grade and TUNEL was significantly higher (p< 0.001) in AMG compared to the control samples which showed an average of 2% TUNEL overall. Upstream markers of apoptosis (Active Caspase 3, Cytochrome C, Active Bax), assessed qualitatively, were present in a similar distribution to that of TUNEL staining. 3-Nitrotyrosine was also shown to be a predominantly surface phenomenon. There was a significant difference (p< 0.001) between regions, ranging from 58% (most damaged) to 10% (undamaged). Again, this was significantly higher that the control samples (p< 0.001). In line with indicators of ROS mediated damage, Bim and FOXO3A were also detected.

Discussion: The mechanism of apoptosis in OA cartilage has not been studied in depth, and understanding the biochemical and molecular responses of ‘stressed’ chondrocytes may provide invaluable information about the specific causes of cell death. Such cellular responses may provide targets for disease modification, thus delaying or preventing the need for joint arthroplasty. We conclude that AMG is a phenotype demonstrating cartilage at progressive stages of disease. Apoptosis involves the intrinsic mitochondrial pathway and ROS appear to be implicated. Further work is needed to provide evidence of what lies further upstream of markers demonstrated in this study.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 541 - 541
1 Oct 2010
Pandit H Beard D Dodd C Goodfellow J Jenkins C Murray D Price A
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Introduction: Most unicompartmental knee replacements (UKRs) employ cement for fixation of the prosthetic components to the bone. The information in the literature about the relative merits of cemented and cementless UKR is contradictory, with some favouring cementless fixation while others favouring cemented fixation. There is concern about the radiolucency which frequently develops around the tibial component with cemented fixations. The exact cause of the occurrence of radiolucency is unknown but according to some, it may suggest suboptimal fixation.

Method: Following ethical approval, 62 patients with medial OA were randomised to receive either cemented (n=31) or cementless components (n=31). All patients underwent identical surgical procedure with either a cemented or cementless Oxford UKR. Patients were assessed clinically and radiologically. The x-rays were taken with an image intensifier (I.I.). The position of the I.I. was adjusted until it was perfectly aligned with the tibial bone-implant interface thereby allowing accurate assessment of presence and extent of the radiolucency.

Results: The patients in the two groups were well matched. There was no significant difference in the clinical scores between the two groups. The mean OKS for the cemented group was 40 (± 8.3) and 42 (± 4.6) for cementless group. Narrow radiolucent lines were seen at the bone-implant interfaces of 75% of the cemented tibial components; partial in 43% and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. The differences are statistically highly significant (p< 0.0001) and imply satisfactory bone ingrowth into the cementless implants.

Conclusions: The method of fixation influences the incidence of radiolucency. With identical designs, no patient with cementless components developed any complete radiolucency. The observation raises the question as to whether cementless rather than cemented components should be routinely used for UKR.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_III | Pages 412 - 413
1 Jul 2010
Price A Longino D Svard U Kim K Weber P Fiddian N Shakespeare D Keys G Beard D Pandit H Dodd C Murray D
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Purpose: The purpose of this study was to report the mid-term survival results of Oxford UKAs in patients of 50 years of age or less, using (1) revision surgery and (2) Oxford Knee Scores (OKS) as outcome measures.

Method: A literature review identified studies of Oxford mobile bearing UKAs containing individuals 1) 50 years old or less with 2) medial osteoarthritis and 3) 2 years or longer follow-up. Authors were approached to participate in a multi-centre survival analysis by submitting all their patients, 50 years of age or less, who received a medial UKA for osteoarthritis. Patients who had died, been lost to follow-up or who underwent revision were identified. OKS were established for all patients with surviving implants.

Results: Seven centres submitted 107 patients. The mean age was 47 years (range 32–50). The average follow-up was 4 years (range 1–25). Forty-seven patients had follow-up into their fifth year or longer. The cumulative 7-year survival using revision as the endpoint was 96% (CI 8). The mean post-operative OKS for surviving implants was 38 (CI 2) out of a possible 48.

Conclusion: While early survival rates and function are encouraging, long-term follow-up is required before concluding UKA is a viable treatment option in young patients with unicompartmental knee arthritis.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_III | Pages 412 - 412
1 Jul 2010
Matthews JJ Williams K Mahendra G Mahoney D Swales C Sabokar A Price A Athanasou N Gibbons CLMH
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Inflammatory changes in synovial tissues occur commonly in knee osteoarthritis (OA) and are termed “inflammatory OA”. The pathogenic significance of this inflammatory OA is uncertain. It is also not known whether inflammatory changes in the synovial membrane are reflected in the synovial fluid (SF) and whether the SF contains a similar inflammatory cell infiltrate.

This study examined 34 cases of knee joint OA and cytologically and immunohistochemically characterised inflammatory cells in the synovial membrane and SF. Specimens of SF and synovial membrane were taken at the time of knee arthroplasty.

All cases of inflammatory OA synovium contained (CD68+) macrophages; several cases also contained a scattered, focally heavy (CD3+) lymphocytic infiltrate and occasional lymphoid aggregates. Inflammatory changes in OA SF reflected this cell composition with numerous CD68+ macrophages and CD3+ lymphocytes being noted in inflammatory OA cases. The SF volume was greater (> 5ml) in cases of inflammatory OA. Non-inflammatory OA knee joints contained very few inflammatory cells, which were mainly macrophages, in both the synovial membrane and SF.

Our findings indicate that inflammatory changes in the synovial membrane of OA knee joints are reflected in the SF and that the volume of SF is commonly increased in cases of inflammatory OA. Both macrophages and lymphocytes in the inflammatory infiltrate of knee joint SF may contribute to joint destruction in OA by providing mononuclear phagocyte osteoclast precursors and the production of inflammatory cytokines and growth factors that promote osteoclastogenesis.

In conclusion, the cytology of SF and synovitic membrane are similar in inflammatory OA. With knee effusions of greater than 5mls and inflammatory synovitic membrane consideration of total knee arthoplasty in the presence of single compartment disease should be considered because of the risk of further joint destruction.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_III | Pages 416 - 416
1 Jul 2010
Bottomley N McNally E Ostlere S Beard D Gill H Kendrick B Jackson W Gulati A Simpson D Murray D Dodd C Price A
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Introduction: This study explores whether modern magnetic resonance imaging (MRI) with improved cartilage sequencing is able to show a more detailed view of anteromedial osteoarthritis of the knee (AMOA). Preoperative assessment of patients and selection of intervention is very important and preoperative imaging forms an integral part of this. Modern MRI technology may allow us to visualize in great detail the structures and cartilage within the knee, providing a better understanding of the pathoanatomy of AMOA. This will be useful in preoperative assessment and surgical management of patients.

Methods: 50 patients with a radiographic diagnosis of anteromedial osteoarthritis of the knee and had been listed for unicompartmental knee arthroplasty (UKA) had MRI as part of their pre-op workup. At operation all were deemed suitable for UKA using the current Oxford indications. The image sequences were coronal, axial and sagittal with a predetermined cartilage protocol. The state of the ACL, cartilage wear location and pattern, presence of osteophytes and subchondral high signal were assessed.

Results: All the ACLs were visualized and in continuity, however 40% showed intrasubstance high signal.

100% of medial compartments showed full thickness anteromedial loss with preservation of the posteromedial cartilage. When present, the meniscus was extruded in 96% of cases.

90% of lateral compartments were normal and none had full thickness cartilage loss. However 10% showed high signal in the tibial plateau.

There was a highly reproducible pattern of osteophyte formation; 94% posteromedial and posterolateral aspect of medial femoral condyle; 90% medial tibial; 80% medial femoral and 84% lateral intercondylar notch.

Discussion: This study maps the pattern of anteromedial osteoarthritis using modern MRI techniques. This has importance in determining preoperative indications (preservation of ACL and posteromedial cartilage); surgical technique (determine pattern of osteophytes requiring resection) and potentially important for long-term outcome (early lateral compartment changes).


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_II | Pages 340 - 340
1 May 2010
Witteveen A Jerosch J Verdonk R Price A Bailleul F Chevalier X Pavelka K
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Introduction: Viscosupplementation is an effective treatment for patients suffering from knee osteoarthritis (OA). Most available products use 3 or 5 injection regimens. The objective of this study was to compare the safety and efficacy of a single 6 mL intra-articular administration of hylan G-F 20 with placebo.

Methods: In this prospective, multicenter, randomized, double-blind study, patients diagnosed with knee OA were randomized to one 6-mL injection of hylan G-F 20 or saline. The primary efficacy analysis (WOMAC A) was performed on the intent-to-treat population and was based on a repeated-measures model over the 26 weeks of the study. The incidence of adverse events (AEs) was collected over the study duration

Results: 253 patients were randomized to hylan G-F 20 (n=124) or placebo (n=129). Mean age was 63 years (42–84), BMI 29.4 (19.5–52.4 kg/m2), 71% were female, and all had primary knee OA of Kellgren Lawrence grade 2 (45%) or 3 (55%). Patients in the hylan G-F 20 group experienced a mean change from baseline in their WOMAC A Likert pain score (0–4 scale) over 26 weeks (primary efficacy criteria) of −0.84, which was statistically significantly different from the change reported in the placebo group (−0.69, p=0.047). Statistically significant differences favoring hylan G-F 20 were also reported for most of the secondary efficacy criteria: WOMAC A1 (estimate Odds Ratio over 26 weeks placebo/hylan G-F 20, 0.64, p=0.013), patient global assessment (0.69, p=0.029), and clinical observer global assessment (0.71, p=0.041); WOMAC B and C changes were not statistically significant between groups. There was no statistically significant difference in the use of rescue medication between the 2 groups. There were no serious AEs related to treatment. In the target knee, injection-related AEs occurred in 4.9% and 3.1% of patients for hylan G-F 20 and placebo, respectively, and treatment-related AEs occurred in 3.3% and 0.8% of patients, respectively. All target knee AEs were local pain, with or without joint swelling or effusion, and were of mild or moderate intensity.

Conclusion: This double-blind placebo-controlled study showed one injection of hylan G-F 20, possibly repeated 6 months later, was safe and provided symptomatic relief lasting up to 6 months in patients with knee OA.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 414 - 414
1 Sep 2009
Simpson D Pandit H Gulati A Gray H Beard D Price A Murray D Gill H
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Statement of purpose: The aim of this study is to evaluate different designs of unicompartmental knee replacement (UKR) by comparing the peak von Mises and contact stresses in polyethylene (PE) bearings over a step-up activity.

Summary of Methods: A validated finite element (FE) model was used in this study. Three UKR designs were modelled: a spherical femoral component with a spherical PE bearing (fully-congruent), a poly-radial femoral component with a concave PE bearing (semi-congruent), and a spherical femoral component with a flat bearing (non-congruent).

Kinematic data from in-vivo fluoroscopy measurements during a step-up activity was used to determine the relative tibial-femoral position as a function of knee flexion angle for each model. Medial and lateral force distribution was adapted from loads measured in-vivo with an instrumented implant during a step-up activity. The affect that varying the bearing thickness has on the stresses in the bearing was investigated. In addition, varus-valgus mal-alignment was investigated by rotating the femoral component through 10 degrees.

Summary of Results: Only the fully congruent bearing experienced peak von Mises and contact stresses below the PE lower fatigue limit (17MPa) for the step-up activity (fully congruent PE peak contact stress, 5MPa). The highest PE contact stresses were observed for the semi-congruent and non-congruent designs, which experienced approximately 3 times the PE lower fatigue limit. Peak PE von Mises stresses for the semi-congruent and non-congruent designs were similar, peaking at approximately 25MPa. Peak PE von Mises stresses were ameliorated with increased bearing thickness. Varus-valgus mal-alignment had little effect on the peak stresses in the three UKR designs.

Statement of Conclusions: Fully congruent articulating surfaces significantly reduce the peak contact stresses and von Mises stresses in the bearing. The FE model demonstrates that fully congruent bearings as thin as 2.5mm can be used without increasing the contact stresses significantly. Fully congruent designs can use thinner bearings and enable greater bone preservation.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 412 - 412
1 Sep 2009
Pandit H Jenkins C Gill H Beard D Marks B Price A Dodd C Murray D
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Introduction: The results of the mobile bearing Oxford unicompartmental knee replacement (UKR) in the lateral compartment have been disappointing with a five year survival of 82%. Therefore, it is recommended that mobile bearings should not be used for lateral UKR. This low survivorship is primarily due to high dislocation rate, all occurring in the first year. A detailed analysis of the causes of bearing dislocation confirmed the elevated lateral tibial joint line to be a contributory factor. A new surgical technique was therefore introduced in which care was taken neither to remove too much bone from the distal femur nor to over tighten the knee and therefore ensure that the tibial joint line was not elevated. Other modifications to the technique were also introduced including use of a domed tibial component.

Aim: The aim of this study is to compare the outcome of these iterations: the original series [series I], Series II with improved surgical technique and the domed tibial component [Series III].

Method: The primary assessment of outcome was bearing dislocation at one year. One year was chosen as all the dislocations in the first series occurred within a year. In series I, there were 53 knees, in series II 65 knees and in series III 60 knees, all with a minimum of one year follow up.

Results: In series I, there were 6 bearing dislocations (11%) and the average range of movement (ROM) was 110°. In the second series, there were 2 dislocations (3%) and the average ROM was 118°. In the third series, there were no primary dislocations and the average ROM was 125°.

Conclusions: The improved surgical technique and implant design has reduced the dislocation rate to an acceptable level so a mobile bearing can now be recommended for lateral UKR.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 414 - 414
1 Sep 2009
Simpson D Gray H Dodd C Beard D Price A Murray D Gill H
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Statement of purpose: Finite element (FE) models of bone can be used to evaluate new and modified knee replacements. Validation of FE models is seldom used, and the quantification of modelling parameters has a considerable effect on the results obtained. The aim of this study is to develop a FE model of a cadaveric tibia and validate it against a comprehensive set of experiments.

Summary of Methods: Seventeen tri-axial rosettes were attached to a cleaned, fresh frozen cadaveric human tibia and the tibia was subjected to 13 loading conditions. Deflection and strain data were used for comparison with the FE model. A geometric model was created on the basis of computed tomography (CT) scans. The CT data was used to map 600 orthotropic material properties to the tibia. All experiments were simulated on the FE model. Measured principal strains were compared to their corresponding FE values using regression analysis. The validated tibia model was reduced in size (75mm to the proximal) and then re-modelled to represent only the proximal tibia. This re-modelled tibia was validated against the reduced size FE model. Virtual surgery was performed on the validated proximal model to implant a UKR.

Summary of Results: For the whole tibia model, the regression line for all axial loads combined had a slope of 0.999, an intercept of −6.24 micro-strain, and an R2 value of 0.962. The root mean square error as a percentage was 5%. For the proximal tibia model, correlation coefficients of 0.989 and 0.976 were obtained for the maximum and minimum principal strains respectively.

Statement of Conclusions: An FE model of an implanted proximal tibia has been validated against experimental data. This model is able to accurately predict the deflection and stresses in a replaced knee joint to obtain clinically relevant information. This will provide a virtual model of unicompartmental arthroplasty, where variables such as fixation method and bearing mechanics can be assessed.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 422 - 422
1 Sep 2009
Gulati A Chau R Palan J Rout R Dodd C Price A Gill H Murray D
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Purpose: To compare the site of lesions in medial and lateral unicompartmental osteoarthritis (OA) of the knee.

Methods: Patients with medial (n=35) and lateral (n=15) OA, having unicompartmental knee arthroplasty, were recruited. Intra-operatively, the distance between the anterior, posterior, medial and lateral margins of the full-thickness lesion and reference lines dividing the condyles was measured. The midpoints of lesions were calculated and groups were compared. Lateral radiographs were used to determine the relationship between the lesion site and knee flexion angle (KFA).

Results: Femoral lesion: In lateral OA, the midpoint of lesions was 25.0mm (SD:8.8) posterior to the reference line passing transversely through the apex of the inter-condylar notch. This was significantly different (p< 0.001) from midpoint in medial OA, which was 10.7mm (SD:9.4) posterior to the reference line.

Tibial lesion: In lateral OA, the midpoint of lesions was 2.0mm (SD:6.5) posterior to the reference line passing through the mid-coronal plane of the resected tibia. This was located significantly more posterior (p=0.038) than midpoint in medial OA, which was 2.2mm (SD:5.7) anterior to the reference line.

Knee Flexion Angle: In lateral OA, the midpoint of lesions was on average at 40° flexion and sites of smaller lesions were very variable. The lesion expanded both anteriorly and posteriorly. In medial OA, smaller femoral lesions occurred in full extension and extended further posteriorly with disease progression.

No significant difference was demonstrated in medial and lateral localisation of the lesions.

Conclusion: Medial OA begins near full extension, progresses in a predictable manner and is perhaps initiated by events occurring at heel strike. Lateral OA begins in flexion in a less predictable manner, at KFA above that seen during the gait cycle. The different sites of lesions in medial and lateral OA suggest different aetiology and pathophysiology. Therefore, prevention and treatment strategies should be different.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 416 - 416
1 Sep 2009
Price A van Dijk NC Verdonk R Jerosch J Chevalier X Bailleul F Pavelka K
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Purpose: The objective of this study was to compare the safety and efficacy of 1 × 6 mL intra-articular administration of hylan G-F 20 with placebo.

Methods: In this prospective, multicenter, randomized, double-blind study, patients diagnosed with knee OA were randomized to one 6-mL injection of hylan G-F 20 or saline. The primary efficacy analysis (WOMAC A) was performed on the intent-to-treat population and was based on a repeated-measures model over the 26 weeks of the study.

Results: 253 patients were randomized to hylan G-F 20 (n=124) or placebo (n=129). Mean age was 63 years (42–84), BMI 29.4 (19.5–52.4 kg/m2), 71% were female, and all had primary knee OA of Kellgren Lawrence grade 2 (45%) or 3 (55%). Patients in the hylan G-F 20 group experienced a mean change from baseline in their WOMAC A Likert pain score (0–4 scale) over 26 weeks (primary efficacy criteria) of −0.84, which was statistically significantly different from the change reported in the placebo group (−0.69, p=0.047). Statistically significant differences favoring hylan G-F 20 were also reported for most of the secondary efficacy criteria: WOMAC A1 (estimate Odds Ratio over 26 weeks placebo/hylan G-F 20, 0.64, p=0.013), patient global assessment (0.69, p=0.029), and clinical observer global assessment (0.71, p=0.041); WOMAC B and C changes were not statistically significant between groups. The OMERACT-OARSI responder analysis indicated that 59% of the patients were responders in the hylan G-F 20 group versus 51% in placebo group (0.66, p=0.059). There was no statistically significant difference in the use of rescue medication (acetaminophen) between the 2 groups.

Discussion and Conclusion: This double-blind placebo-controlled study showed one injection of hylan G-F 20 provided symptomatic relief lasting up to 6 months in patients with knee OA; it avoids the need for multiple injections.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 412 - 412
1 Sep 2009
Pandit H van Duren B Jenkins C Gill H Beard D Price A Dodd C Murray D
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Introduction: Treatment options for the young active patient with isolated symptomatic medial compartment OA and pre-existing ACL deficiency are limited. Implant longevity and activity levels may preclude TKA, whilst HTO and unicompartmentasl knee arythroplasty (UKA) are unreliable due to ligamentous instability. UKAs tend to fail because of wear or tibial loosening resulting from eccentric loading. Combined UKA and ACL reconstruction may therefore be a solution.

Method: Fifteen patients with combined ACL reconstruction and Oxford UKA (ACLR group), were matched (age, gender and follow-up period) with 15 patients with Oxford UKA with intact ACL (ACLI group). Prospectively collected clinical and x-ray data from the last follow-up (minimum 3 years, range: 3 – 5) were compared. Ten patients from each group also underwent in-vivo kinematic assessment using a standardised protocol.

Results: At the last follow-up, the clinical outcome for the two groups were similar. One ACLR patient needed revision due to infection. Radiological assessment did not show any significant difference between relative component positions and none of the patients had pathological radiolucencies suggestive of component loosening. Kinematic assessment showed posterior placement of the femur on tibia in extension for the ACLR group, which corrected with further flexion.

Conclusions: The short-term clinical results of combined ACL reconstruction and UKA are excellent. Lack of pathological radiolucencies and near normal knee kinematics suggest that early tibial loosening due to eccentric loading is unlikely.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 426 - 426
1 Sep 2009
McDonnell S Thomas G Rout R Osler S Pandit H Beard D Gill H Dodd C Murray D Price A
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Aim: The aim of this study was to asses the accuracy of skyline radiographs in the assessment of the patellofemoral joint, when compared to open intraoperative assessment.

Methods: Eighty nine patients undergoing knee replacement surgery were included in the study. Skyline radiographs were obtained preoperatively. These radiographs were assessed and graded by an experienced musculoskeletal radiologist using the Altman and Ahlbäck classifications. The grades were calculated for both the medial and lateral facets of the PFJ. Intraoperative assessment of the Patellofemoral joint was undertaken at the time of surgery. The damage was graded using the modified Collins classification (0: Normal, 1: Superficial damage, 2: Partial thickness cartilage loss, 3: Focal Full thickness cartilage loss < 2cm2, 4: Extensive full thickness cartilage loss < 2cm2). Data was obtained for the Medial Facet, Lateral Facet and Trochlea.

Results: Spearman’s rank correlation coefficient between the radiographic and macroscopic changes within the lateral PFJ were poor with both the Altman 0.22 (p=0.0350) and Ahlbäck 0.24 (p=0.018). The correlation of the medial PFJ was slightly better with a coefficient for Altman 0.42 (P< 0.0001) and Ahlbäck 0.34 (P> 0.001).

Conclusion: In conclusion skyline radiographs provide a poor to moderate preoperative assessment of the degree of osteoarthritis within the patella-femoral joint. This has significant implications for establishing radiographic criteria for planning patella-femoral joint replacement.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 410 - 410
1 Sep 2009
Longino D Hynes S Rout R Pandit H Beard D Gill H Dodd C Murray D Cooper C Javaid M Price A
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Purpose: The aim of this study is to compare the long-term survival results of TKA in patients under the age of 60, using

revision surgery and

poor functional outcome as the end-points.

Method: From our knee database we identified a cohort of 60 total knee replacements that had been performed over 15 years previously. We identified those who had died, those who had been revised and established the Oxford Knee Score (OKS) for all those still surviving.

Results Using the following endpoint criteria the cumulative 15-year survival was (A) revision surgery alone = 78% (CI 12), (B) revision surgery or an OKS less than or equal to 24 (50% of total OKS) = 63% (CI 13), and (C) revision surgery or moderate pain = 48% (CI 14).

Conclusion The functional survival of TKA in patients under the age of 60 decreases in the second decade following implantation with a significant number of prostheses failing the patient due to knee pain


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 421 - 421
1 Sep 2009
Campion J Masters S Byren I Berendt A Price A
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Purpose: The purpose of this study was to establish patient mortality following salvage treatment (debridement, retention of prosthesis and antibiotic therapy) for infection of primary joint replacement, performed at the unit.

Method: A series of 89 patients underwent salvage treatment for infected primary total joint replacement (47 hips and 42 knees) between 1998 and 2003. The average age of the patients was 70.3 years (range 31.8 to 89.1). A survival analysis was performed using death as the sole endpoint and there were no patients lost to follow-up.

Results: There were a total of 26 deaths with a mean time to death of 3.3 years (range 0.8 to 7.2). The 7-year cumulative patient survival of was 66% (CI 5, number at risk 21).

Conclusions: The morbidity associated with infected total arthroplasty has been well documented. This study highlights that patients undergoing salvage treatment for this condition have significant mortality, with up to a third of patients potentially dying by 7 years.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 412 - 412
1 Sep 2009
Pandit H Jenkins C Beard D Gill H Marks B Price A Dodd C Murray D
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Introduction: The information in the literature about the relative merits of cemented and cementless unicompartmental knee replacement (UKR) is contradictory, with some favouring cementless fixation while others favouring cemented fixation. Cemented fixations give good survivorship but there is concern about the radiolucency which frequently develops around the tibial component. The exact cause of the occurrence of radiolucency is unknown but according to some, it may suggest suboptimal fixation.

Method: Sixty-two knees (31 in each group) were randomised to receive either cemented or cementless UKR components. The components were similar except that the cementless had a porous titanium and hydroxyappatite (HA) coating. Patients were prospectively assessed by an independent observer pre-operatively and annually thereafter. The clinical assessment included Oxford Knee Score, Knee Society Scores and Tegner activity score. Fluoroscopically aligned radiographs were assessed for thickness and extent of radiolucency under the tibial implant.

Results: At one year there were no differences in the clinical outcome between the groups and there were no loose components. No radiolucencies thicker than 1mm were seen. At one year none of the cementless tibias and 30% of the cemented tibias had complete radiolucencies. One out of 31 cementless (3%) and 12 out of 31 cemented (39%) had partial radiolucencies. This difference between these two groups was high significant (p< 0 0001).

Conclusions: This study clearly demonstrates that the incidence of radiolucency beneath the tibial component is influenced by component design and method of fixation. With identical designs of tibial component none of the cementless components developed complete radiolucences whereas 30% of the cemented components did. We conclude that HA achieves better bone integration than cement.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_III | Pages 468 - 469
1 Sep 2009
Rout R Mcdonnell S Hollander A Clark I Simms T Davidson R Dickinson S Waters J Gill H Murray D Hulley P Price A
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The aim of this study was to investigate the molecular features of progressive severities of cartilage damage, within the phenotype of Anteromedial Osteoarthritis of the Knee (AMOA).

Ten medial tibial plateau specimens were collected from patients undergoing unicompartmental knee replacements. The cartilage within the area of macroscopic damage was divided into equal thirds: T1(most damaged), to T3 (least damaged). The area of macroscopically undamaged cartilage was taken as a 4th sample, N. The specimens were prepared for histological (Safranin-O and H& E staining) and immunohistochemical analysis (Type I and II Collagen). Immunoassays were undertaken for Collagens I and II and GAG content. Real time PCR compared gene expression between areas T and N.

There was a decrease in OARSI grade across the four areas, with progressively less fibrillation between areas T1, T2 and T3. Area N had an OARSI grade of 0 (normal).

The GAG immunoassay showed decreased levels with increasing severity of cartilage damage (ANOVA P< 0.0001). There was no significant difference in the Collagen II content or gene expression between areas. The Collagen I immunohistochemistry showed increased staining within chondrocyte territorial areas in the undamaged region (N) and immunoassays showed that the Collagen I content of this macroscopically and histologically normal cartilage, was significantly higher than the damaged areas (ANOVA P< 0.0001). Furthermore, real time PCR showed that there was a significant increase in Collagen I expression in the macroscopically normal areas (p=0.04).

In AMOA there are distinct areas, demonstrating progressive cartilage loss. We conclude that in this phenotype the Collagen I increase, in areas of macroscopically and histologically normal cartilage, may represent very early changes of the cartilage matrix within the osteoarthritic disease process. This may be able to be used as an assay of early disease and as a therapeutic target for disease modification or treatment.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 576 - 576
1 Aug 2008
Howells NR Carr AJ Price A Rees JL
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Objective: To investigate the effect of lab based simulator training, on the ability of basic surgical trainees to perform diagnostic knee arthroscopy.

Method: 20 orthopaedic SHO’s with minimal arthroscopic experience were randomised to 2 groups. 10 received a fixed protocol of simulator based arthroscopic skills training. This consisted of 3 sessions of 6 simulated arthroscopies using a Sawbones bench-top knee model. Their learning curve was assessed objectively using motion analysis. Time taken, path length and number of movements were recorded. All 20 then spent an operating list with a blinded consultant trainer. They received instruction and demonstration of diagnostic knee arthroscopy before performing the procedure independently. Their performance was assessed using the intra- operative section of the Orthopaedic Competence Assessment Project (OCAP) procedure based assessment (PBA) protocol for diagnostic arthros-copy and further quantified with a global rating assessment scale.

Results: In theatre, simulator-trained SHO’s outscored all but one untrained SHO. The simulator trained group were scored as competent on more than 70% of occasions compared to less than 15% for the un-trained group (p< 0.05). The mean global rating score of the trained group was 24.4 out of 45 compared with 12.4 for the untrained group (p< 0.05). Motion analysis demonstrated objective and significant improvement in performance during simulator training.

Conclusion: The use of lab based arthroscopic skills training leads to subsequent significant improvement in operating theatre performance. This may suggest that formalised lab based training should be a standardised part of future surgical curricula. OCAP PBA’s appear to provide a useful framework for assessment however potential questions are raised about the ability of OCAP to truly distinguish levels of surgical competence.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 578 - 578
1 Aug 2008
Price A Xia Z Hulley P Murray D Triffitt J
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Aim: The aim of this study was to investigate whether viable chondrocytes can be isolated and subsequently expanded in culture, from cryopreserved intact human articular cartilage.

Method: Human articular cartilage samples, retrieved from patient undergoing total knee replacement, were cored as 5 mm diameter discs then minced to approximately 0.1 mm3 size pieces. Samples were cryopreserved at the following stages; intact cartilage discs, minced cartilage and chondrocytes immediately after enzymatic isolation. After completing of isolation, cell viability was examined using LIVE/DEAD fluorescent staining. Isolated chondrocytes were then cultured and a cell proliferation assay was performed at day 4, 7, 14, 21 and 28 days.

Results: The results showed that the viability of isolated chondrocytes from control, cryopreserved intact AC discs, minced AC and isolated then frozen samples were 71.84 ± 2.63%, 25.61 ± 2.41%, 31.32 ± 2.47 % and 42.53 ± 4.66% respectively. Isolated chondrocytes from all groups were expanded by following degrees after 28 days of culture; Group A: 10 times, Group B: 18 times, Group C: 106 times, and Group D: 154 times.

Conclusion: We conclude that viable chondrocytes can be isolated from cryopreserved intact human AC and then cultured to expand their number. This method could be employed to patients benefit undergoing autologous chondrocyte implantation.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 577 - 577
1 Aug 2008
McDonnell S Rout R Dodd C Murray D Price A
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Anteromedial osteoarthritis is a distinct phenotype of osteoarthritis. The arthritic lesion on the tibia is localised to the anteromedial quadrant with an intact ACL. Deficiency of the ACL leads to a progression to tricompartmental disease. Within the spectrum of intact ACL a varying degree of ligament damage is seen. Our aim was to correlate the progression of ACL damage to the geographical extent of disease and the degree of cartilage loss on the tibial plateau.

We systematically digitally mapped 50 tibial plateau resection specimens from clinical photographs of patients undergoing unicompartmental arthroplasty, additionally the damage to their ACL was graded (0: normal, 1:synovium loss, 2:longitudinal splits)

These images were imported into image analysis software. Accurate measurements were made of the dimensions of the specimen. Measurements included the AP distance to the anterior and posterior aspect of the lesion, and the distance to the start of the macroscopically non damaged cartilage. The areas of cartilage damage and full thickness loss were also recorded. The results were represented as a % of total area to account for variation in size of the resection specimens. We compared % of full thickness loss in patients with normal to those with damaged, but functionally intact ligaments.

All specimens had a similar macroscopic appearance. A significant difference was seen with the progression of ACL damage and area of eburnation of bone. Using an unpaired t test, a significant difference in area of % full thickness cartilage loss (P=0.047) was seen between patients with a normal and longitudinal splits within their ACL. No correlation between the clinical status of the ACL and start or finish point of cartilage loss on the tibial plateau

We surmise that the progression from anteromedial to tricompartmental osteoarthritis of the knee may be related to the graduated damage of the ACL.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 577 - 577
1 Aug 2008
McDonnell S Sinsheimer J Dodd C Murray D Carr A Price A
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A sibling risk study that shows a statistically significant increase in risk for anteromedial osteoarthritis of the knee.

Anteromedial osteoarthritis is a distinct phenotype of osteoarthritis. Previous studies have shown a genetic aetiology to both hip and knee osteoarthritis. The aim of this study was to determine the sibling risk of antero-medial osteoarthritis of the knee.

We conducted a retrospective cohort study of 132 probands with primary anteromedial osteoarthritis, who had undergone unicompartmental arthroplasty. Sibling were identified as having symptomatic knee problems by postal Oxford Knee Score (OKS). A positive OKS was defined as an OKS+/− 2SD of the mean of the proband group. Sibling spouses were used as controls. Those siblings & spouses that were symptomatic from the OKS were invited to undergo Knee X-rays, to look for radiological signs of osteoarthritis. Osteoarthritis was diagnosed as greater than Grade II on the Kell-gren Lawrence classification. The pattern of disease was noted and it was considered if the sibling were suitable for a unicompartmental knee arthroplasty. The prevalence and sibling risk of anteromedial osteoarthritis was determined using a randomly selected single sibling per proband family. The prevalence was determined in the 103 single proband sibling pairs.

There was a statistically significant risk within the sibling group P= 0.024 using the Chi square test. The relative risk of anteromedial osteoarthritis was. 3.21(95% CI 1.08 to 9.17)

Genetic factors play a major role in the development of anteromedial osteoarthritis.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 579 - 579
1 Aug 2008
Price A Svard U
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Aim: This paper presents the 20-year survival and 10-year clinical follow-up results from the entire series of all medial Oxford meniscal bearing unicompartmental knee arthroplasties performed in a single centre in Sweden, between 1985 and 2004.

Method: Patients were contacted and information about the state of the knee collected. Revision surgery was used in the life-table survival analysis performed. For the entire cohort clinical follow up at 10-years is routinely performed, using the HSS knee score.

Results: The entire group comprised of 683 knees in 572 patients. The mean age at implantation was 69.7 (range 48–94). There had been 30 revision procedures: 8 for lateral arthrosis, 7 for component loosening, 3 for infection, 6 for bearing dislocation, 1 for bearing fracture and 5 for unexplained pain. The 10-year, 15-year and 20-year survival (all cause revision) were 94.1 % (CI 2.9, 237 at risk), 93.5% (CI 4.6, 101 at risk) and 92.3% (CI 15.1, 11 at risk) respectively. From the patients reviewed clinically the mean pre-operative HSS knee score was 57 (95% CI 1), compared to 87 (95% CI 1) at 10-years. Using HSS criteria the results were: 68% excellent, 23% good, 6% moderate and 2% poor.

Conclusion: The results show that this mobile bearing unicompartmental prosthesis offers patients excellent clinical results during the first decade and is durable during the second decade after implantation.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 391 - 391
1 Jul 2008
McDonnell S Benson R Hulley P Athanasou N Carr A Price A
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Antero-medial osteoarthritis of the knee displays a well recognised pattern of cartilage damage on the medial tibial plateau. Anteriorly there is a full thickness cartilage defect, with transition to a partial thickness defect, becoming full thickness in the posterior third of the plateau. The retained posterior cartilage is macroscopically normal, but no previous study has assessed its histo-logical features. This study characterises the histological changes, to examine if antero-medial OA of the knee represents a model of progressive osteoarthritic cartilage damage.

Five unicompartmental resection specimens of patients with idiopathic single compartment antero-medial osteoarthritis were assessed. The samples were stained with H& E and Saffinin-O stains and reviewed using the Mankin system, an established method for scoring osteoarthritic changes in cartilage (range 0 [normal] to 14 [grossly osteoarthritic]) Digital images of the histology were reviewed by two observers to exclude inter and intra observer error. Each specimen was assessed at 4 interval points (A,B,C,D) along the A-P axis starting from the most posterior aspect of the exposed bone to the area of macroscopically normal cartilage. Three repeat measurements were taken from the macroscopically normal region (D1,D2,D3). The scores were compared to historical age matched controls of non-osteoarthritic cartilage, where a Mankin grade of < 3 suggests normal cartilage.

From anterior to posterior the H& E staining showed a consistent decrease in structural integrity and cellularity of the cartilage, matched by a qualitative decrease in GAG content (Saffinin-O staining). Mean Mankin scores showed a progressive decrease in score; A = 14.0 (95% CI 0), B = 5.8 (95%CI 2.4), C = 4.4 (95%CI 2.5), D = 1.0 (95%CI 0.9) {p=0.04 ANOVA}. Repeated measurements at the macroscopically normal area showed the Mankin grade was maintained; D1= 1.0 (95%CI 0.9), D2 = 0.6 (95%CI 0.5), D3 = 0.6 (95%CI 0.6).

The results show that the retained posterior cartilage in antero-medial arthritis has a consistently normal Mankin grade. We suggest the defect represents a model of progressive cartilage damage from near normal (posterior) to the grossly osteoarthritic state (anterior).


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_I | Pages 101 - 101
1 Mar 2006
Langdown A Pandit H Price A Dodd CAF Murray D Svoerd Gibbons C
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Introduction This study assesses the outcome of medial unicompartmental knee arthroplasty (UKA) using the Oxford prosthesis for end-stage focal spontaneous osteonecrosis of the knee (SONK, Ahlback grades III & IV).

Methods A total of 29 knees (27 patients) with SONK were assessed using the Oxford Knee Score. Twenty-six had osteonecrosis of the medial femoral condyle; 3 had osteonecrosis of the medial tibial plateau. This group was compared to a similar group who had undergone Oxford Medial UKA for primary osteoarthritis. Patients were matched for age, sex and time since operation.

Results Mean length of follow-up was 5.2 years (range 1–13 years). There were no implant failures in either group, but there was one death 9 months post-arthroplasty from unrelated causes in the group with osteonecrosis. The mean Oxford Knee Score (SD) in the group with osteonecrosis was 37.8 (7.6) and 40.0 (6.6) in the group with osteoarthritis. There was no significant difference between the two groups using Student’s t-test (p=0.29).

Interpretation Use of the Oxford Medial UKA for focal spontaneous osteonecrosis of the knee is reliable in the short to medium term, and gives similar results to when used for patients with primary osteoarthritis.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 344 - 344
1 Sep 2005
Hollinghurst D Stoney J Ward T Robinson B Price A Gill H Beard D Dodd C Newman J Ackroyd C Murray D
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Introduction and Aims: Single compartmental replacement procedures are increasingly preferred over total knee replacement (TKR) for single compartment osteoarthritis of the knee joint. Theoretically, reduced disruption of the native joint should produce more normal kinematics. This study aimed to describe and compare the sagittal plane kinematics of four different, commonly used devices.

Method: Four groups of patients who had undergone successful single compartment replacement at least two years previously were recruited. Fifteen following Oxford medial UKA, 12 following medial St Georg Sled UKA, five following Oxford lateral UKA, and 12 following Avon PFJ replacement. Patients performed flexion/extension against gravity, and a step-up during video fluoroscopy. The Patellar Tendon Angle (PTA), the angle between the long axis of the tibia and the patella tendon, was obtained as a function of knee flexion. This relationship provides indication of sagittal movement between femur and tibia through range and has been validated as a reliable measure of joint kinematics.

Results: The kinematic profile for each group was compared to that of the profile for 12 normal and 30 TKR (AGC) knees. All three tibiofemoral devices produced knee kinematics similar to the normal knee. The PTA was found to have a linear relationship to flexion angle, decreasing with increasing knee flexion angle. No such linear relationship exists for the TKR joint, which display abnormal kinematics. The PF device also reflected similar trends to that for normal knees except that the PTA was moderately increased throughout the entire range of flexion (three degrees).

Conclusion: In contrast to TKR, all single compartmental knee replacements provided kinematics similar to the normal joint. The kinematic pattern of the PFJ replacement may be of most interest as the observed increase in PTA through range could influence patello-femoral contact forces


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_II | Pages 147 - 147
1 Apr 2005
Beard D Murray D Pandit H Dodd C Price A Butler-Manuel A Goodfellow J
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Introduction and Aims A randomised controlled trial (RCT) and a multi-centre unilateral cohort study were performed as part of the stepwise introduction of a new mobile bearing knee. The aim was to ensure that outcome for the new device was at least as good as that for an established fixed bearing device. This paper presents three year follow up of the published one year results. Instability and prevalence of “clicking” from the joint were examined in detail.

Method 1. A multi-centre RCT of patients undergoing bilateral knee replacement compared functional outcome between two different prostheses, the new mobile bearing device (TMK) and an established fixed bearing device (AGC). 2. A separate multi-centre cohort of 166 patients who had undergone a unilateral mobile bearing procedure at least six months previously was used to assess complication rate and corroborate any findings from the bilateral trial. Outcome measures included Oxford Knee Scores, American Knee Society ratings and complication rate.

Results The bilateral trial revealed no significant differences in outcome between the two devices. Revision rate for all (199) mobile bearing knees was less than 2%. The mean Oxford Knee Score for outcome for all mobile bearing knees was 37.1 ± 10.1. About 7% of patients reported instability. Clicking was more common in the TMK (48%) than in the AGC (30%) and was reported as a problem in 16% of TMK’s in the cohort study. However, clicking was unrelated to outcome score in both studies.

Conclusion At three years, the mobile bearing device was as good as the fixed bearing device. There was a relatively high prevalence of “clicking” in the TMK but the cause remains unclear. Furthermore, the symptom was not associated with poor functional outcome. The bilateral RCT and cohort study allows assessment of function and potential problems. It provides rigourous scientific justification for the introduction and early assessment of new implants.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_IV | Pages 421 - 421
1 Apr 2004
Short A O’Brien S Price A Murray D McLardy-Smith P
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Polyethylene wear remains an important cause of failure in knee replacements. Retrieval studies, simulators and simple X-ray methods produce wear data that may be inaccurate or unrealistic. We have developed an accurate RSA system for measuring wear in-vivo. Using this system we have found wear rate in a fixed bearing TKR to be about 0.1mm/yr[1]. In this abstract we extend the study to fully congruent mobile bearings.

Four Oxford uni-compartmental knee replacements, with excellent clinical results were studied ten years after implantation. RSA X-rays were taken in double leg stance with the knee in full extension and 15 and 30 degrees flexion. Following RSA calibration, silhouettes of the components on the stereo X-rays were extracted using a Canny edge detector and were matched to silhouettes projected using CAD models to determine the 3D component position. The average minimum thickness of the bearing was determined and was compared with the measured minimum thickness of 14 unused bearings to calculate linear penetration.

The average linear penetration after average 10 years implantation (range 8.5 to 10.25 years) was 0.16 mm (SD 0.13 mm). The average penetration rate was 0.017 mm/year (SD 0.011 mm/year). The maximum linear penetration rate was 0.027 mm/year.

The penetration rate is similar to that obtained in a retrieval study [2]. Compression of the bearing is minimal due to 6sqcm of contact area. This study therefore demonstrates that polyethylene wear on the upper and lower surfaces is minimal in fully congruous mobile bearing knee replacements.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 308 - 308
1 Mar 2004
Rea P Short A Pandit H Price A Murray D
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Introduction: Radiolucencies are frequently observed around joint replacements. Their signiþcance & etiology remain unclear. Aim: 1. To study radiolucency under tibial tray of Oxford UKA and correlate it to the clinical outcome. 2. To study implant migration using RSA and study the correlation between migration and radiolucency. Materials and Methods: Fifty consecutive patients cemented Oxford UKA with a minimum follow up of two years were studied. At 2 years precisely aligned radiographs were obtained and evaluated for presence and extent of radiolucency under the tibial tray. The patients were divided into two groups Ð those with (Group I) and those without presence of radiolucency under the tibial tray (Group II). All the patients were assessed using KSS. Patients had RSA marker balls inserted around the prosthesis at the time of index procedure. Using RSA, the degree and direction of implant movement was measured at 1 & 2 yrs post surgery. Results: A) There were 26 patients in group I and 24 in group II. Both the groups were well matched for age and sex distribution. There was no signiþcant difference between the two groups when various clinical scores were compared. Maximum width of radiolucency was 1.1 mm and the average width was 0.57 mm. B) RSA study: By 12 months, the tibial component had migrated signiþcantly distally (mean: 0.42 mm, S.D.: 0.15 mm) and anteriorly (mean: 0.47 mm, S.D. 0.27mm). No signiþcant migration occurred after 12 mths. There was no correlation between presence or extent of radiolucency and migration of the tibial component. Conclusion: There is no relationship at 2 years between radiolucency and clinical results. There is also no relationship between radiolucency and migration. Therefore radiolucencies of 1mm or less can be ignored


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_I | Pages 18 - 19
1 Jan 2004
Rea P Short A Kyberd P Pandit H Price A Murray D O Connor J
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Radiolucencies are generally thought to be a manifestation of loosening. They are commonly seen under the tibial component of the Oxford Unicompartmental knee replacement. However, they are not associated with long term failure [1]. The aim of this study was to investigate any relationship between radiolucencies and component migration.

Eight medial Oxford Unicompartmental knee prostheses were examined post-operatively, at 12 months and at 24 months using Roentgen Stereophotogrammetric Analysis (RSA). The serial radiographs were calibrated and three dimensional CAD models were matched to the extracted component shapes. Implanted bone marker balls were then selected on all radiographs. The components were superimposed. Migration calculation was achieved by comparing relative positions of components to bone marker balls in the serial radiographs. Fluoroscopically screened X-rays were taken to determine whether there were any radiolu-cencies under the tibial component.

By 12 months, the femoral component had migrated significantly anteriorly (0.35 mm) and proximally (0.61 mm). The tibial component had migrated significantly distally (0.42 mm) and anteriorly (0.47 mm). Although on average there appeared to be a small further migration between 12 and 24 months, this was not statistically significant in any direction.

Six of the eight patients had radiolucencies at 24 months. None of the radiolucencies were was complete. The maximum radiolucency was 1 mm thick and the average was 0.57 mm. There was no correlation between radiolucency and migration.

The proximal femoral migration and distal tibial migration can be explained by the load across the knee. We cannot yet explain the anterior tibial migration. Radiolucencies almost always occur and are not related to migration.This confirms they are not associated with loosening.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_I | Pages 18 - 18
1 Jan 2004
Robinson B Halliday S Price A Beard D Rees J Dodd C Murray D Goodfellow J O’Connor J
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When the Oxford unicompartmental meniscal bearing arthroplasty (UCA) is used in the lateral compartment of the knee 10% of the bearings dislocate. An in-vitro cadaveric study was performed to investigate if the anatomy and joint geometry of the lateral compartment was a contributory factor in bearing dislocation. More specifically, the study investigated if the soft tissue tension of the lateral compartment, as determined by the length of the lateral collateral ligament (LCL), was related to bearing dislocation. A change in length of greater than 2 mm is sufficient to allow the bearing to dislocate.

The Vicon Motion Analysis System (Oxford Metrics, Oxford, UK) was used to assess length changes in the LCL of seven cadaveric knees. Measurements were made of the LCL length through knee flexion and of the change in LCL length when a varus force was applied at a fixed flexion angle. Measurements were made in the normal knee and with the knee implanted with the Oxford prosthesis.

In the intact knee the mean LCL change was 5.5mm (8%) over the flexion range. After implantation with the Oxford UCA the mean change in length was only 1 mm (1%). There was a significant difference in the LCL length at 90° (p=0.03) and 135° (p=0.01) of knee flexion compared to the intact knee. When a varus force was applied the LCL length change of the intact knee (5.4 mm) was significantly different (p=0.02) to that of the knee with the prosthesis implanted (2.7 mm)

This study used a new method to dynamically measure LCL length. It found that after implantation of the Oxford lateral UCA the LCL remains isometric over the flexion range and does not slacken in flexion as it in the normal knee. This would suggest that the soft tissue tension was adequate to contain the bearing within the joint.

However, when a varus force was applied the LCL did not sufficiently resist a displacing force producing an LCL length change greater than 2 mm.

The evidence provided by this study is contradictory. The “lack of change in LCL length through flexion” suggests that the ligament remains tight through range and is unlikely to allow dislocation. However, the amount of distraction possible when an adducting moment is applied is sufficient to allow bearing dislocation. The length tension properties of the lateral structures are therefore implicated in the mechanism of dislocation.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_I | Pages 16 - 16
1 Jan 2004
Price A Short A Kellett C Rees J Pandit H Dodd C McLardy-Smith P Gundle R Murray D
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The aim of the study was to measure in-vivo the 10-year linear and volumetric polyethylene wear of a fully congruent mobile bearing unicompartmental knee arthroplasty (OUKA).

We studied six OUKA’s that had all been implanted 10 years previously. Each patient was examined in even double leg stance at a range of knee flexion angles, in a calibration cage. A stereo pair of X-ray films was acquired for each patient at 0°, 15° and 30° of flexion. The films were analysed using an RSA style calibration and a CAD model silhouette-fitting technique. The position and orientation of each femoral and tibial component was found relative to each other and the bearing position inferred. Penetration of the femoral component into the original volume of the bearing was our estimate of linear wear. The volumetric wear is calculated from the measured linear wear and the known surface area of the bearing. In addition eight control patients were examined less than 3 weeks post-operation where no wear would be expected.and 30We studied seven OUKA’s that had all been implanted at least 10 years previously. A stereo pair of X-ray films was acquired for each patient at 0 Results: The control group showed no measured wear. The seven OUKA’s had an average maximum depth of linear penetration of 0.40 mm at a mean follow-up of 10.9 years. The linear wear rate was 0.033 mm/year. The volumetric material loss was 79.8 mm3. If a steady gradual material loss is assumed, 8 mm3 of UHMWPE was lost per year.

Polyethylene particulate wear debris continues to be implicated in the aetiology of component loosening and implant failure knee following arthroplasty. The OUKA employs a spherical femoral component and a fully congruous meniscal bearing to increase contact area and theoretically reduce the potential for polyethylene wear. The results from this in-vivo study confirm that the device has low 10-year linear and volumetric wear in clinical practice. This may protect the device from component loosening in the long term.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_I | Pages 12 - 12
1 Jan 2004
Pandit H Price A Rees J Beard D Gill H Dodd C Murray D
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The indications for unicompartmental knee arthroplasty (UKA) can be contentious. Concerns exist about implanting a UKA in younger individuals. It has been reported that it is contra-indicated in patients under the age of 60. The suggestion is that younger patients may compromise their outcome after surgery by their increased activity levels. However, the number of publications with data on UKA in young patients is minimal and the age/activity related criteria for UKA remains unknown.

The aim of the study was 1) to confirm that younger UKA patients have higher activity levels than older patients, and 2) to test the hypothesis that younger, more active patients have inferior outcome when compared to older less active patients.

Fifty consecutive patients undergoing UKA who were under 60 years (Group Y) and 50 patients over 60 years (Group O) were recruited. Indications were anteromedial arthritis with full thickness lateral compartment cartilage, a functioning ACL and a correctible varus. All patients underwent Oxford UKA using the minimally invasive technique. This device employs an unconstrained fully congruous meniscal bearing. Outcome was evaluated using Knee Society Scores. Activity level was documented using Tegner Activity Score.

Average age of patients for group Y and O was 55 and 68 years respectively. Minimum follw-up was 2 years. pre-op. knee scores were comparable for each group. (y: 38.8, O: 35.8) and patients in both groups siginificantly improved after surgery. A significant difference in Tegner score was found between the two groups after surgery (y:4.1, O:2.6). More than 50% of younger patients regularly participated in high demand activities like skiing, tennis and manual labour. No statistically significant differences in any other post op. knee scores or complication rate were found despite adequate study power.

Younger patients have increased activity levels after UKA when compared to an older age group. There is no evidence that the outcome of UKA in younger more active patients will be inferior to those who are older and more sedentary.