Abstract

Introduction

Virtual fracture clinics (VFC's) aim to reduce the number of outpatient appointments while improving the clinical effectiveness and patients experience through standardisation of treatment pathways. With 4.6% of ED admissions due to trauma the VFC prevents unnecessary face to face appointments providing a cost savings benefit to the NHS.

This study aimed to examine the effect of high tibial osteotomy (HTO) on the ankle and subtalar joints via analysis of static radiographic alignment. We hypothesised that surgical alteration of the alignment of the proximal tibia would result in compensatory distal changes.

35 patients recruited as part of the wider Biomechanics and Bioengineering Centre Versus Arthritis HTO study between 2011 and 2018 had pre- and postoperative full-length weightbearing radiographs taken of their lower limbs. In addition to standard alignment measures of the limb and knee (mechanical tibiofemoral angle, Mikulicz point, medial proximal tibial angle), additional measures were taken of the ankle/subtalar joints (lateral distal tibial angle, ground-talus angle, joint line convergence angle of the ankle) as well as a novel measure of stance width. Results were compared using a paired T-test and Pearson's correlation coefficient.

Following HTO, there was a significant (5.4°) change in subtalar alignment. Ground-talus angle appeared related both to the level of malalignment preoperatively and the magnitude of the alignment change caused by the HTO surgery; suggesting subtalar positioning as a key adaptive mechanism. In addition to compensatory changes within the subtalar joints, the patients on average had a 31% wider stance following HTO. These two mechanisms do not appear to be correlated but the morphology of the tibial plafond may influence which compensatory mechanisms are employed by different subgroups of HTO patients.

These findings are of vital importance in clinical practice both to anticipate potential changes to the ankle and subtalar joints following HTO but it could also open up wider indications for HTO in the treatment of ankle malalignment and osteoarthritis.

Abstract

Abstract

Noise induced hearing loss (NIHL) is a common cause of preventable deafness in adults and exposure to loud noise at work is a significant risk factor for its development. In order to protect the hearing of workers in the U.K., the Health and Safety Executive (HSE), on behalf of the Department for Work and Pensions, established the Control of Noise at Work Regulations (2005). The objectives of this study were to define the levels of noise exposure for the surgeon, assistant, scrub nurse and anaesthetist during total hip and knee arthroplasty surgery. In addition, we sought to determine whether the noise exposure during these procedures reaches or exceeds the action values set out by the U.K. Noise at Work Regulations (2005). To our knowledge no real-time assessment of personal noise exposure has been performed simultaneously on multiple members of the theatre team during arthroplasty surgery.

Individual noise exposure during arthroplasty hip and knee surgery was recorded using a personal noise dosemeter system model 22 (DM22) (Pulsar instruments, Filey, U.K.). Recordings were taken real-time during five separate theatre sessions. Each theatre session included two arthroplasty procedures and lasted approximately 4hrs. Personal noise exposure was expressed in terms of peak sound pressure and an average noise exposure over an 8-hour time-period to reflect the noise experienced by the ear over a working day.

In all three sessions involving total hip replacement surgery the peak sound pressure, for the operating surgeon, exceeded the exposure action values set out by the U.K. Noise at Work Regulations. Theatre sessions involving total knee replacement surgery did not exceed any exposure action values.

The peak sound pressures experienced during total hip replacement surgery are too high and mandate that the surgeon should be provided with appropriate hearing protection. In addition, if the upper exposure action value is routinely exceeded then the theatre should be designated a hearing protection zone.

Abstract

Abstract

Abstract

Robotic-assisted technology in total knee arthroplasty (TKA) aims to increase implantation accuracy, with real-time data being used to estimate intraoperative component alignment. Postoperatively, Perth computed tomography (CT) protocol is a valid measurement technique in determining both femoral and tibial component alignments. The aim of this study was to evaluate the accuracy of intraoperative component alignment by robotic-assisted TKA through CT validation. A total of 33 patients underwent TKA using the MAKO robotic-assisted TKA system. Intraoperative measurements of both femoral and tibial component placements, as well as limb alignment as determined by the MAKO software were recorded. Independent postoperative Perth CT protocol was obtained (n.29) and compared with intraoperative values. Mean absolute difference between intraoperative and postoperative measurements for the femoral component were 1.17 degrees (1.10) in the coronal plane, 1.79 degrees (1.12) in the sagittal plane, and 1.90 degrees (1.88) in the transverse plane. Mean absolute difference between intraoperative and postoperative measurements for the tibial component were 1.03 degrees (0.76) in the coronal plane and 1.78 degrees (1.20) in the sagittal plane. Mean absolute difference of limb alignment was 1.29 degrees (1.25), with 93.10% of measurements within 3 degrees of postoperative CT measurements. Overall, intraoperatively measured component alignment as estimated by the MAKO robotic-assisted TKA system is comparable to CT-based measurements.

Background

Orthopaedic surgeons are exposed to high levels of noise when performing common surgical procedures. Noise induced hearing loss (NIHL) has been demonstrated amongst senior orthopaedic staff. The objective of this study was to investigate the prevalence of hearing loss amongst arthroplasty surgeons compared to non-surgical clinicians and explore the factors associated with hearing loss.

Aims

COVID-19 has changed the practice of orthopaedics across the globe. The medical workforce has dealt with this outbreak with varying strategies and adaptations, which are relevant to its field and to the region. As one of the ‘hotspots’ in the UK , the surgical branch of trauma and orthopaedics need strategies to adapt to the ever-changing landscape of COVID-19.

Introduction

The intra-operative diagnosis of Prosthetic Joint Infection (PJI) is a dilemma requiring intra-operative sampling of suspicious tissues for frozen section, deep tissue culture and histopathology to secure a diagnosis. Alfa defensin-1 testing has been introduced as a quick and reliable test for confirming or ruling out PJI. This study aims to assess its intra-operative reliability compared to the standard tests.

Introduction

Revision total hip arthroplasty is a complex procedure and becoming more common. Acetabular implant loosening or fracture has previously been treated with a cup and cage construct. Recent studies have shown significant failure rates with Cup Cage constructs in more complex 3B and 3C Acetabular revisions. As a result the use of 3D printed custom made acetabular components has become more common.

Introduction

Despite improvement in implants and surgical techniques up to 20% of Total Knee Arthroplasty TKA patients continue to report dissatisfaction. The ATTUNE Knee System was designed to provide better patellar tracking and stability through the mid-range of flexion and therefore improve patient outcomes and satisfaction.

Introduction & aims

The magnitude and pattern of acceptable migration in clinically successful cementless stems is not well understood. Radiostereometric analysis (RSA) is a well-recognised method of assessing implant migration.

Previous studies have reported long term RSA results for cemented stems. The aim of this study was to assess the long-term migration characteristics of the Corail hydroxyapatite-coated cementless stem at 10 years using RSA.

Focal cartilage defects (FCDs) found in medial and lateral compartments of the knee are accompanied with patient-reported pain and loss of joint function. There is a deficit of evidence to explain why they occur. We hypothesise that aberrant knee joint loading may be partially responsible for FCD pathology, therefore this study aims to use 3-dimensional motion capture (MoCap) analysis methods to investigate differences in gait biomechanics of subjects with symptomatic FCDs.

11 subjects with Outerbridge grade II FCDs of the tibiofemoral joint (5 medial compartment, 6 lateral compartment) and 10 non-pathological controls underwent level-gait MoCap analysis using an infra-red camera (Qualisys) and force-plate (Bertec) passive marker system. 6-degree of freedom models were generated and used to calculate spatio-temporal measures, and frontal and sagittal plane knee, hip and ankle rotation and moment waveforms (Visual 3D). Principle component analysis (PCA) was used to score subjects based on common waveform features, and PC scores were tested for differences using Mann-Whitney tests (SPSS).

No group differences were found in BMI, age or spatio-temporal measures. Medial-knee FCD subjects experienced higher (p=0.05) overall knee adduction moments (KAMs) compared to controls. Conversely, lateral-knee FCD subjects found lower (p=0.031) overall KAMs. Knee flexion and extension moments (KFMs/KEMs) were relatively reduced (p=0.013), but only in medial FCD subjects. This was accompanied by a significantly (p=0.019) higher knee flexion angle (KFA) during late-stance.

KAMs have been shown to be predictive of frontal plane joint contact forces, and therefore our results may be reflective of FCD subjects overloading their respective diseased knee condyles. The differences in knee sagittal plane knee moments (KFMs/KEMs) and angles (KFA) seen in medial FCD subjects are suggestive of gait adaptations to pain. Overall these results suggest treatments of FCDs should consider offloading the respective affected condyle for better surgical outcomes.

Total knee arthroplasty is associated with early postoperative pain. Appropriate pain management is important to facilitate postoperative rehabilitation and positive functional outcomes. This study compares outcomes in TKA with three techniques; local infiltration analgesia, single shot femoral nerve block and intrathecal morphine.

Introduction

Patients undergoing total knee arthroplasty have expected blood loss during and after surgery. The current literature remains inconclusive in regards to which surgical instrumentation techniques in total knee arthroplasty are effective in minimising peri-operative blood loss. The primary objective of this retrospective review of a prospective randomized cohort study is to compare surgical and patient factors and their influence on blood loss and transfusions rates between one type of Patient Specific Instrumentation (PSI) (SignatureTM), Navigated Computer-Assisted Surgery (CAS) and Conventional Total Knee Arthroplasty (TKA) surgical techniques.

Background

Total knee arthroplasty is associated with early postoperative pain. Appropriate pain management is important to facilitate postoperative rehabilitation and positive functional outcomes. This study compares outcomes in TKA with three techniques; local infiltration analgesia, single shot femoral nerve block and intrathecal morphine.

Introduction

Total hip replacement (THR) is a very common procedure performed for the treatment of osteoarthritis of the hip. The aim of THR is to restore function and quality of life of the patients, by restoring femoral offset, leg length, centre of rotation, and achieving stability, to avoid dislocation postoperatively.

Background

Shoulder impingement syndrome (SIS) is a common debilitating condition, treated across multiple health disciplines including Orthopaedics, Physiotherapy, and Rheumatology. There is little consistency in diagnostic criteria with ‘Shoulder impingement syndrome’ being used for a broad spectrum of complex pathologies. We assessed patterns in diagnostic procedures for SIS across multiple disciplines.

Introduction

There are conflicting views when assessing the best imaging modality by which to assess long leg alignment pre and post operatively for patients’ receiving primary total hip replacements. It has been a long standing standard that long-leg radiographs are used for measuring and interpreting alignment of the lower limb, but recently it has been suggested that CT imaging may be a better option for this assessment.

Alignment and soft tissue balance are two of the most important factors that influence early and long term outcome of total knee arthroplasty.

Current clinical practice involves the use of plain radiographs for preoperative planning and conventional instrumentation for intra operative alignment.

The aim of this study is to assess the Signature^TM Personalised system using patient specific guides developed from MRI. The Signature^TM system is used with the Vanguard^RComplete Knee System. This system is compared with conventional instrumentation and computer assisted navigation with the Vanguard system.

Patients were randomised into 3 groups of 50 to either Conventional Instumented Knee, Computer Navigation Assisted Knee Arthroplasty or Signature Personalised Knee Arthoplasty. All patients had the Vanguard Total knee Arthroplasty Implanted.

All patients underwent Long leg X-rays and CT Scans to measure Alignment at pre-op and 6 months post-op. All patients had clinical review and the Knee Society Score (KSS) at 1 year post surgery was used to measure the outcome.

A complete dataset was obtained for 124 patients. There were significant differences in alignment on Long leg films ot of CT scan with perth protocol. Notably the Signature group had the smallest spread of outliers.

In conclusion the Signature knee system compares well in comparison with traditional instrumentation and CAS Total Knee Arthroplasty.

Background

Safety and efficacy of novel prostheses relies on the determination of early implant migration and subsequent risk of loosening. Radiostereometric Analysis (RSA) has been used to evaluate the clinical failure risks of femoral stems by reporting distal migration, a measure of stem subsidence, when examining early migration characteristics. The migratory patterns of femoral stems, 24 months postoperatively, have provided a surrogate outcome measure to determine implant stabilisation and predict long-term performance and survivorship. RSA assessed femoral stem migration and provided comparison of the early migration characteristics with published data of a clinically established counterpart.

Inter- and intra-observer variation has been noted in the analysis of radiographic examinations with regard to experience of surgeons, and the monitors used for conducting the evaluations. The aim of this study is to evaluate inter/intra observer variation in the measurement of mechanical alignment from long-leg radiographs.

40 patients from the elective waiting list for TKA underwent long leg radiographs pre-operatively and 6 months post-operatively (total of 80 radiographs). The x-rays were analysed by 5 observers ranging in experience from medical student to head orthopaedic surgeon. Two observers re-analysed their results 6 months later to determine intraobserver correlation, and one observer re-measured the alignment on a different monitor. These measurements were all conducted blindly and none of the observers had access to the others’ results.

80 radiographs were analysed in total, 40 pre-op and 40 post-op. The mechanical alignment was analysed using Pearson's correlation (r = 0 no agreement, r = 1 perfect agreement) and revealed that experience as an orthopaedic surgeon has little effect on the measurement of mechanical alignment from long leg radiograph. The results for the different monitor analysis were also analysed using Pearson's correlation of long leg alignment. Monitor quality does seem to affect the correlation between alignment measurements when reviewing both intra and inter observer correlation on different computer monitors.

Surgical experience has little impact on the measurement of alignment on long leg radiographs. Of greater concern is that monitors of different resolution can affect measurement of mechanical alignment. As there might be a range of monitors in use in different institutions, and also in outpatient clinics to surgical theatres, close attention should be paid to the implications of these results.

Risk factors for poor outcomes after total knee replacement (TKR) have been identified, but the underlying causes are not fully understood. The aim of this research was to establish the relationship between measurable gait parameters and patients' subjective function, pre and post total knee replacement. 25 subjects underwent gait analysis, before and one year following total knee replacement. Patient reported function was investigated using the Activities of Daily Living Scale of the Knee Outcome Survey (KOS). Gait analysis was performed using infrared cameras and reflective marker clusters. Correlation between motion analysis data and patient reported function was investigate. Whilst multiple gait parameters correlated with KOS score preoperatively, there was no correlation after TKR. Three preoperative measurements correlated with the improvement in score a subject achieved following surgery: These were preoperative rate of extension in swing, total range of flexion from heel strike and time point of maximum stance extension. Our results suggest that whilst preoperatively there is a close relationship between knee biomechanical function and patient reported function, after TKR factors other than biomechanical function determine patient outcomes.

Introduction

Total Knee Arthroplasty (TKA) aims to deliver relief from pain and restore normal function. Unfortunately, a significant cohort of patients report poor outcomes.

BACKGROUND

High tibial Osteotomy (HTO) realigns the forces in the knee to slow the progression of osteoarthritis. This study relates the changes in knee joint biomechanics during level gait to glutamate signalling in the subchondral bone of patients pre and post HTO. Glutamate transmits mechanical signals in bone and activates glutamate receptors to influence inflammation, degeneration and nociception in arthritic joints. Thus glutamate signalling is a mechanism whereby mechanical load can directly modulate joint pathology and pain.

Purpose of study

To determine whether cycles of pivot shift testing prior to anterior cruciate ligament (ACL) reconstruction alters metabolite levels in synovial fluid.

Background

Patellofemoral replacement is an established intervention in selected patients with severe isolated patellofemoral osteoarthritis. FPV (Wright Medical, UK) is a third generation patellofemoral arthroplasty implant and is the second most used after AVON in National Joint Registry for England and Wales. Reports of survivorship and functional of this implant are scarce in literature.

Aim

To determine the effect of the use of radial extracorporeal shockwave therapy (rESWT) in the treatment of patellar tendinopathy.

INTRODUCTION

Motion analysis is routinely used in the clinical and research sectors to quantify joint biomechanics. It plays an important role in clinical assessments by aiding the physician to distinguish between primary movement abnormalities and any secondary compensatory mechanisms that may overshadow the cause of the problem. During a data collection session, a wealth of biomechanical data regarding joint and segment kinematics and kinetics are collected from patients performing daily activities. Objective classification can be used to automate a diagnosis from this data and has been used previously to analyse measurements of level gait [1]. It is of interest to assess the knee during stair-gait as this activity involves greater range of motion (ROM) of the lower limbs, larger forces and moments acting at the knee.

INTRODUCTION

Useful feedback from a Total Knee Replacement (TKR) can be obtained from post-surgery in-vivo assessments. Dynamic Fluoroscopy and 3D model registration using the method of Banks and Hodge (1996) [1] can be used to measure TKR kinematics to within 1° of rotation and 0.5mm of translation, determine tibio-femoral contact locations and centre of rotation. This procedure also provides an accurate way of quantifying natural knee kinematics and involves registering 3D implant or bone models to a series of 2D fluoroscopic images of a dynamic movement.

Glutamate is a neurotransmitter that transmits mechanical signals in bone (1) and activates glutamate receptors and transporters, in bone, cartilage, meniscus and synovium (2). Glutamate receptor activation influences inflammatory, degenerative and nociceptive pathways in arthritic joints (2). Thus glutamate signalling is a mechanism whereby mechanical load can directly influence joint pathology and pain. We have investigated components of glutamate signalling in the subchondral bone of patients with osteoarthritis to determine which are expressed and whether this varies in anatomical regions subject to different loads. Subchondral bone was sampled from tibial cuts derived from total knee arthroplasty (n=2, TKR, Kellgren Lawrence grade 3) and from tibial drill hole sites from high tibial osteotomy (n=5, HTO, KL grades 2 and 3) for osteoarthritis. RNA was extracted, reverse transcribed and RT-PCR performed for a housekeeping gene GAPDH, a glutamate transporters (EAAT-1, EAAT1ex9skip), glutamate receptors (NR2A and KA1), a bone matrix protein, osteocalcin, and signaling molecules (osteoprotegerin [OPG], RANKL). We found differential mRNA expression in different regions of subchondral bone. In one TKR patient, EAAT-1 expression was significantly reduced in the anterior zone versus the middle or posterior zones of the tibial plateau (ANOVA, p<0.001). HTO bone cores were subdivided medial/lateral and anterior/posterior. Good quality RNA was obtained from bone cores removed from drill holes during HTO surgery, with GAPDH, osteocalcin, EAAT-1, EAAT1ex9skip, NR2A, KA1, OPG and RANKL mRNA expression detected. In one patient, comparison of gene expression in bone cores obtained pre and post HTO revealed that EAAT1ex9skip was rarely detected in post-op bone whereas KA1 was rare in pre-op bone. This differential mRNA expression may be due to the altered loading through the joint caused by the osteotomy, although these on/off differences need to be quantified to confirm this.

We have shown that glutamate transporters and receptors are expressed in human subchondral bone. Activation of these receptors and transporters by the increased synovial fluid concentrations of glutamate released in arthritis will influence pathological changes and nociception. In some patients, glutamate transporter mRNA expression appears to vary with anatomical location in bone, or after HTO surgery, consistent with our original discovery of this transporter as mechanically-regulated in bone (1). If glutamatergic signaling is mechanically regulated in the human knee, this will vary during arthritic disease progression and after joint realignment, providing a direct mechanism linking mechanical loading through the joint to pathology and pain in arthritis.

Osteoarthritis (OA)

is the most common arthritic condition. OA causes joint pain, loss of mobility and significantly affects the quality of life for the affected individual. The major burden to patients with arthritis is pain. However, often radiological joint destruction and the extent of pain do not correlate. This causes a dilemma for clinicians in advising timing for joint replacement surgery. In arthritis, concentrations of the neurotransmitter, glutamate is increased within the synovial fluid activating both peripheral pain mechanisms and pathological processes (1). Other pathological/pain related metabolites are also released into synovial fluid, which provides a real time snap shot of the joint pathology. We have tested the hypothesis that ‘The increased levels of pain and disease-related metabolites within human synovial fluids from arthritic joints can be detected and quantified ex vivo using high resolution 1H-NMR.’

Meniscal tears commonly occur after a traumatic twisting injury to the knee (acute) or can form over time (degenerate). Symptoms include pain, swelling, and ‘locking’ of the knee. These symptoms are also commonly associated with osteoarthritis (OA). In some cases of OA, degenerative meniscal tears can also be present making it difficult to determine the cause of symptoms. Furthermore, acute meniscal lesions may be associated with early stage OA but often no radiological signs are evident. Many metabolites associated with joint disorders are released into the synovial fluid providing a real-time snap shot of joint pathology. The ability to examine concentrations of specific metabolites within synovial fluid could provide invaluable clinical information about the cause and stage of joint pathology. We have tested the hypothesis that ‘high resolution 1H-NMR can discriminate between osteoarthritic and meniscal tear-related metabolites within human synovial fluids and aid in clinical diagnosis.’

Purpose: Since the neurotransmitter glutamate mediates nociceptive and pathological processes in arthritis, we have investigated how glutamate receptor and transporter expression varies with anatomical site or disease severity in subchondral bone of patients with osteoarthritis.

Methods and Results: Subchondral bone was sampled from tibial cuts derived from total knee arthroplasty (n=2, TKR, Kellgren Lawrence[KL] grade 3) and from tibial drill hole sites from high tibial osteotomy (n=2, HTO, KL grades 2 and 3) for osteoarthritis. RNA was extracted, reverse transcribed and RT-PCR performed for the housekeeping gene GAPDH, the glutamate transporter EAAT-1, and glutamate receptors (NR2A and KA1). Quantitative RT-PCR assessed differences in the expression of EAAT-1, a dominant negative splice variant called EAAT-1ex9skip and osteocalcin after normalisation to GAPDH.

Good quality RNA was obtained from bone cores removed from drill holes during HTO surgery, with GAPDH, EAAT-1, NR2A and KA1 expression detected. Osteocalcin expression was high indicating RNA was derived from osteoblasts and osteocytes, but did not vary with anatomical site or disease status. End-stage RT-PCR indicated differential expression of EAAT-1 between medial and lateral bone samples in total knee arthroplasty, however these differences were not significant by quantitative RT-PCR. In one patient, EAAT-1 expression was significantly reduced in the anterior zone versus the middle or posterior zones (ANOVA, p< 0.001). EAAT-1ex9skip represented a significant proportion of the total EAAT-1 mRNA expression in bone from TKR patients, but appeared less abundant in HTO samples.

Conclusion: We have shown for the first time that glutamate transporters and receptors are highly expressed in subchondral bone of patients with osteoarthritis and that EAAT-1 expression may vary with anatomical location and pathology. Activation of these receptors and transporters by the increased synovial fluid concentrations of glutamate that occur in arthritis may contribute to pathological changes and nociception.

The aim of this study was to evaluate the rate of surgical site infection (SSI) in all patients undergoing a primary total knee arthroplasty (TKA) and to audit the outcomes for those who were obese.

We retrospectively reviewed data for 839 primary TKAs done at a National Arthroplasty Centre over one year (April 2007 – March 2008). Body mass index (BMI) data was available for 824 (98%) of the patients. Surgical site infection (SSI) data had been collected prospectively by the Infection Control team for up to 30 days post-operatively and was available for all patients.

There were 23 patients with SSIs, 22 having superficial SSI and only one patient with a deep SSI. The overall superficial SSI rate was 2.7%. For the BMI< 25 group (9.6% of patients) SSI rate was 1.3%. For BMI 25–30 (31.6% of patients) SSI rate was 2.3%. For BMI 30–35 (31.2% of patients) SSI rate was 1.6%. For BMI 35–40 (19.0% of patients) SSI rate was 3.2%. For BMI > (8.6% of patients) SSI rate was 8.5%. Fisher’s Exact Test between all obese patients (BMI< 30) and those with BMI< 30 showed no significant difference in superficial SSI rates (p = 0.39) but did show a significant difference between superficial SSI rates in the obese class III patients (BMI> 40) and the rest of the cohort (p = 0.008).

Obese class III (BMI > 40) patients are at an increase risk of superficial SSI as compared to other patients undergoing primary TKA. However, obese class I and II patients (BMI 30–40) do not appear to have an increased likelihood of superficial SSI as compared to patients who have BMI< 30.

Introduction: The knee joint replacement arthroplasty is a very successful procedure. Traditionally we aim to perform the arthroplasty and recreate the patients’ biomechanical axis and correct the coronal plain alignment deformity. Unfortunately till recently there was no fine way of controlling the exact alignment and depending on surgeon to surgeon, a valgus (to anatomical axis) of 3 to 7 degrees is aimed for using mechanical intra or extramedullary jigs. On proper measurements only 70–80% of knees achieve the aimed result at best as can be seen in the literature. With the advent of computer aided navigation we can now achieve the desired alignment in a much higher percentage of patients.

Material: We performed 1000 total knee arthroplasties at our hospital. Out of these 500 were performed using computer navigation and 500 using conventional mechanical jigs. Pre op and post op long leg alignment films were taken using standardised method. The data was collected using oxford scores and from computer navigation machines and plain radiographic analysis. The observers doing the radiographic analysis were blinded as to whether the patient had procedure done by conventional means or by computer navigation. Sub grouping of the deformities was done depending on the amount of deformity.

Results: 500 patients had the operation done by conventional means and the other 500 with computer navigation guidance. Further subgroups were made depending on the amount of pre-existing radiological deformity 0–5, 6–10, 11–15 and more than 15 degrees of varus or valgus deformity. The effect of gender, bmi, surgeon experience, clinical oxford score outcome was also considered. It was clear that the patients who had more severe deformities and valgus deformities had better post operative alignments after the procedure was performed with computer navigation as compared with the conventional means. There was statistically significant difference observed between the subgroups.

Discussion: Orthopaedic surgery has improved with technical advancements over the number of years. With any new procedure it takes a long time to shed the old beliefs and adapt the new concepts. While we have plenty of evidence in literature and from our study that computer navigation can give better desired alignment after total knee arthroplasty especially with more severe deformities, it still needs to be taken up by majority of orthopaedic surgeons. Ours is the first study to demonstrate the difference in the specific subgroups.

Introduction: The prevalence of obesity continues to increase in the United Kingdom leading to a growing burden on the healthcare system. A significant percentage of patients who undergo total knee arthroplasty are obese. A review of the literature reveals that obese patients are at an increased risk of complications including wound problems. The aim of this study was to evaluate the rate of surgical site infection in all patients undergoing a primary total knee arthroplasty and to audit the outcomes for those who were obese.

Methods: We retrospectively reviewed data for 839 primary total knee arthroplasties done at a National Arthroplasty Centre over one year (April 2007 – March 2008). BMI data was available for 824 (98%) of the patients and was obtained from the patients’ clinical records. Surgical site infection data had been collected prospectively by the Infection Control team for inpatient stays and up to 30 days post-operatively. Infection data was available for all patients. Patients were grouped based on their BMI and the WHO classifications (WHO Technical Report Series 894). The infection rates were analysed to establish if there were poorer outcomes for obese patients.

Results: Based on the WHO classifications, 31.2% of the patients were obese class I (BMI 30 – 35), 19.0% were obese class II (BMI 35 – 40) and 8.6% were obese class III (BMI > 40). There were 23 patients with infections, 22 having superficial infection and only one patient with a deep infection. The overall superficial surgical site infection rate was 2.7%. The superficial surgical site infection rate for the normal weight group was 1.3%, for the overweight group was 2.3%, obese class I was 1.6%, obese class II was 3.2% but for obese class III was 8.5%. The Fisher’s Exact Test between all obese patients and those with BMI < 30 showed no statistically significant difference in superficial surgical site infection rates (p = 0.39). However, it did show a statistically significant difference between superficial surgical site infection rates in the obese class III patients and the rest of the cohort, p = 0.008.

Conclusion: Obese class III (BMI > 40) patients are at an increase risk of superficial surgical site infection as compared to other patients undergoing primary total knee arthroplasty. However, obese class I and II patients do not appear to have an increased likelihood of superficial surgical site infection as compared to patients who have BMI < 30. It is therefore important that surgeons are aware of the higher risk of surgical site infection in obese class III patients and recommended that patients in this category should be informed of this by their surgeon when considering primary total knee arthroplasty.

Purpose of the study: Since the neurotransmitter glutamate mediates nociceptive and pathological processes in arthritis, we have investigated how glutamate receptor and transporter expression varies with anatomical site or disease severity in subchondral bone of patients with osteoarthritis.

Methods and results: Subchondral bone was sampled from tibial cuts derived from total knee arthroplasty (n=2, TKR, Kellgren Lawrence grade 3) and from tibial drill hole sites from high tibial osteotomy (n=2, HTO, KL grades 2 and 3) for osteoarthritis. RNA was extracted, reverse transcribed and RT-PCR performed for the housekeeping gene GAPDH, the glutamate transporter EAAT-1, and glutamate receptors (NR2A and KA1). Quantitative RT-PCR assessed differences in the expression of EAAT-1, a dominant negative splice variant called EAAT-1ex9skip and osteocalcin after nor-malisation to GAPDH.

Good quality RNA was obtained from bone cores removed from drill holes during HTO surgery, with GAPDH, EAAT-1, NR2A and KA1 expression detected. Osteocalcin expression was high indicating RNA was derived from osteoblasts and osteocytes, but did not vary with anatomical site or disease status. End-stage RT-PCR indicated differential expression of EAAT-1 between medial and lateral bone samples in total knee arthroplasty, however these differences were not significant by quantitative RT-PCR. In one patient, EAAT-1 expression was significantly reduced in the anterior zone versus the middle or posterior zones (ANOVA, p< 0.001). EAAT-1ex9skip represented a significant proportion of the total EAAT-1 mRNA expression in bone from TKR patients, but appeared less abundant in HTO samples.

Conclusion: We have shown for the first time that glutamate transporters and receptors are highly expressed in subchondral bone of patients with osteoarthritis and that EAAT-1 expression may vary with anatomical location and pathology. Activation of these receptors and transporters by the increased synovial fluid concentrations of glutamate that occur in arthritis may contribute to pathological changes and nociception.

Purpose: The aim of this study was to evaluate the rate of surgical site infection (SSI) in all patients undergoing a primary total knee arthroplasty (TKA) and to audit the outcomes for those who were obese.

Methods/Results: We retrospectively reviewed data for 839 primary TKAs done at a National Arthroplasty Centre over one year (April 2007 – March 2008). BMI data was available for 824 (98%) of the patients. SSI data had been collected prospectively by the Infection Control team for up to 30 days post-operatively and was available for all patients. Patients were grouped based on their BMI and the WHO classifications (WHO Technical Report Series 894).

31.2% of the patients were obese class I (BMI 30 – 35), 19.0% were obese class II (BMI 35 – 40) and 8.6% were obese class III (BMI > 40). There were 23 patients with SSIs, 22 having superficial SSI and only one patient with a deep SSI. The overall superficial SSI rate was 2.7%. The superficial SSI rates for each group were as follows: normal (BMI < 25) = 1.3%; overweight (BMI 25 –30) = 2.3%; obese class I = 1.6%; obese class II = 3.2%; obese class III = 8.5%. The Fisher’s Exact Test between all obese patients and those with BMI < 30 showed no significant difference in superficial SSI rates (p = 0.39) but did show a significant difference between superficial SSI rates in the obese class III patients and the rest of the cohort (p = 0.008).

Conclusions: Obese class III (BMI > 40) patients are at an increase risk of superficial SSI as compared to other patients undergoing primary TKA. However, obese class I and II patients do not appear to have an increased likelihood of superficial SSI as compared to patients who have BMI < 30.

We describe a new method for reconstructing the patellar tendon following combined injury to the patellar tendon and anterior cruciate ligament (ACL).

Combined injuries to the patellar tendon and the ACL represent a rare and potentially serious injury pattern. The injury to the patellar tendon can often go undiagnosed at primary presentation. Reconstructive options for the patellar tendon are described but can be technically difficult, particularly if ipsilateral hamstring has been used for anterior cruciate ligament reconstruction. Evidence suggests combined injuries generally lead to poor long term outcome.

We describe a case of a 26 year old male who presented with a reconstructed ACL and a patellar tendon deficient knee. Diagnosis was confirmed on Magnetic Resonance Imaging (MRI). Ipsilateral hamstrings had been used as donor for ACL reconstruction. An Achilles tendon allograft with distal bone block was used in combination with contralateral semitendinosus and gracilis autograft to reconstruct the three bundles of the patellar tendon. The patient experienced no postoperative complications and was followed up radiologically and clinically. Computer Topography imaging performed at 6 months post-operatively showed union of the bony Achilles tendon block. MRI performed 1 year post-operatively showed good incorporation of the tendinous grafts and no evidence of degeneration or tearing. Oxford knee score at 6 months post-operatively was 31/48. One year post-operatively full pre-injury activity level had been achieved.

We believe this method to provide adequate strength and integrity, enabling early rehabilitation following this rare injury. It has also been shown to give a good functional outcome.

Purpose of the study: Since glutamate can activate both nociceptive and pathological processes, we have investigated glutamate signalling in patients with painful and asymptomatic meniscal tears to determine which components are expressed, whether this varies in different anatomical regions of the meniscus and whether it is influenced by pain or degeneration.

Methods and results: Meniscus samples were obtained from two patients undergoing arthroscopic partial meniscal resection for chronic degenerate painful meniscal tears, from one patient with a torn painless meniscus and from the less affected compartment of the knee joint of three patients undergoing total knee arthroplasty. Menisci were dissected into anatomical regions (anterior horn, body, posterior horn, inner vascular, outer avascular), cryosectioned and RNA extracted. RNA was reverse transcribed and PCR performed for the housekeeping gene GAPDH and glutamate receptor subunits (NR2A, AMPA GluR3, KA1). Absolute quantitative RT-PCR assessed mRNA expression of glutamate transporters (EAAT-1, EAAT-1ex9skip) and type I collagen after normalisation to GAPDH or total RNA.

Human meniscus expressed GAPDH, type 1 collagen, EAAT-1, EAAT-1ex9skip, NR2A, AMPA GluR3 and KA1 mRNAs. Levels of EAAT-1 expression, normalised to GAPDH, did not differ between the inner and outer halves, or in the anterior, middle or posterior regions of menisci from the less affected compartments of arthritic knees. EAAT-1 expression appeared greater in the 2 painful, compared with the single non-painful meniscus. Interestingly, EAAT-1ex9skip was significantly more common within the outer zones (ANOVA, P=0.040) and in the posterior horns of the menisci (ANOVA, p=0.038).

Conclusion: We have shown for the first time that glutamate receptors and transporters are expressed in human meniscus providing a potential mechanism underlying the pathophysiology of pain associated with a torn meniscus. Our preliminary data indicate that EAAT-1 and EAAT-1ex9skip expression may vary with extent of damage and anatomical location in the human meniscus.

Introduction: Inaccuracies in kinematic data recording due to skin movement artefact are inherent with motion analysis. Image registration techniques have been used extensively to measure joint kinematics more accurately. The aim of this study was to assess the feasibility of using MRI for creating 3D models and to quantify errors in data collection methods by comparing kinematics computed from motion analysis and image registration.

Methodology : 5 healthy and 5 TKR knees were examined for a step up/down task using dynamic fluoroscopy and motion capture. MRI scans of the knee, femur and tibia were performed on the healthy subjects and were subsequently segmented using ScanIP(Simpleware) to produce 3D bone models. Registration of the models produced from fine and coarse scan data was used to produce bony axes for the femoral and tibial models. Tibial and femoral component CAD models were obtained for the TKR patients. The 3D knee solid models and the TKR CAD models were then registered to a series of frames from the 2D fluoroscopic image data (Figure 1) obtained for the 10 subjects, using KneeTrack(S. Banks, Florida) to produce kinematic waveforms. The same subjects were also recorded whilst performing the same action, using a Qualisys (Sweden) motion capture system with a pointer and marker cluster-based technique developed to quantify the knee kinematics.

Results: The motion analysis method measured significantly larger frontal and transverse knee rotations and significantly larger translations than the image registration method.

Conclusion: The study demonstrated that MRI, rather than CT scan, can be used as a non-invasive tool for developing segmented 3D bone models, thus avoiding highly invasive CT scanning on healthy volunteers. It describes an application of combining fine and coarse scan models to establish anatomical or mechanical axes within the bones for use with kinematic modeling software. It also demonstrates a method to investigate errors associated with measuring knee kinematics.

Purposes of the study: Anterior cruciate ligament (ACL) deficiency is associated with degenerative osteoarthritis especially when it is present with meniscal injury; We assessed the impact of certain aetiological factors in chondral degeneration in the ACL deficient knee.

Methodology and Results: Fifty-eight patients who underwent consecutive primary arthroscopic anterior cruciate ligament reconstruction using the four strand hamstring graft between 10/06/2004 and 29/06/2006 were retrospectively analysed.

Patient’s charts and radiology findings were reviewed with special attention to operative notes and preoperative knee MR imaging. Patients with knee symptoms prior to presenting injury were excluded.

The mechanism of injury, the time elapsed from the original injury to anterior cruciate ligament reconstruction, associated meniscal injury, and quality of cartilage in the knee- at the time of MR imaging and ACL reconstruction were noted. Degenerative cartilage changes were graded upon reconstruction using the Outerbridge classification.

The average time from Injury to MR imaging and MR to ACL reconstruction was 4.85 and 12.65 months respectively.

We found a direct relationship between the time elapsed after the ACL injury and the severity of the chondral lesion (p< 0.05). Furthermore, a significant worsening in chondral degeneration of the involved knee was seen when the MR imaging and ACL reconstruction were more than 12 months apart (p< 0.01).

Conclusion: We conclude that chondral lesions and degeneration are more likely to be caused by an extended period of knee instability following ACL injury as opposed to age related degeneration or direct trauma to the weight bearing area of the knee.

Early reconstruction may protect the knee from chondral wear and subsequent degenerative arthritis.

Introduction: The water soluble vitamins B1, B2 and B6 are essential precursors for a wide variety of coenzymes involved in intermediary metabolism. Recent evidence suggests that the systemic inflammatory response associated with disease, injury and infection may lower micronutrient concentrations in plasma independent of tissue stores. Elective knee arthroplasty surgery has been shown to induce a significant and reproducible systemic inflammatory response and therefore provides an ideal model with which to examine the relationship between plasma and erythrocyte (intracellular) concentrations of B-vitamins and the evolution of the systemic inflammatory response.

Methods: The study was approved by the local ethics committee. All subjects were informed of the purpose and procedure of the study and all gave consent. Venous blood samples (EDTA) were withdrawn pre-operatively from 12 primary knee arthroplasty patients and at 12, 24, 48, 72 and 168 hours after the start of surgery. Analysis of plasma and red cell vitamins B1, B2, B6, C-reactive protein and albumin. Data presented as median and range. Data from different time periods were tested for statistical significance using the Freidman test and where appropriate comparisons of data from different time periods were carried out using the Wilcoxon signed rank test.

Results: All patients were over the age of 60 years and had circulating concentrations of B vitamins in the normal range (B1 275–675ng TDP/g Hb; B2 220–410nmol/l; B6 17–135nmol/l). On analysis of serial postoperative values over the study period 0–168hrs there were significant increases in C-reactive protein and significant decreases in albumin concentrations peaking/troughing at 48hrs returning towards normal concentrations at 7 days (p< 0.001). In contrast, during this period plasma albumin (p< 0.001), B2 (p< 0.001) and B6 (p< 0.001) concentrations fell transiently by as much as 50% returning towards normal in parallel with the fall in C-reactive protein concentrations. In contrast, neither red cell B2 nor B6 concentrations fell during the study period.

Conclusions: In this study red blood cell B2 and B6 remained stable over the period of study. In contrast, plasma concentrations of B2 and B6 fell and were outwith the normal range, the trough coinciding with the peak of C-reactive protein before returning to baseline values. These results are consistent with the concept that plasma concentrations of vitamins are unlikely to be a reliable measure of status in patients with evidence of a systemic inflammatory response. Red cell B1, B2 and B6 concentrations more accurately reflect status in patients with evidence of a systemic inflammatory response.

Aims: In this study we present the outcome for patients with the Rotaglide mobile meniscal knee prosthesis implanted for osteoarthritis. Method: All patients reviewed had this prosthesis implanted as a primary total knee Arthroplasty in Crosshouse Hospital. The minimum follow up period was 5 years (range 5–8.2). Patients were assessed clinically by the junior author (CW) and results were standardised using the Hospital for Specialist Surgery (HSS) knee score. Standard radiographs were taken in AP and lateral planes to assess for loosening using the Knee Society roentgenographic system. Case notes were then examined for evidence of peri and postoperative problems. Results: Sixty-seven patients (73 knees) were reviewed. 97% of patients had an excellent clinical outcome with HSS scores of 85 or more. Two knees (2.7%) were revised, one for meniscal fracture and one for meniscal dislocation. There have been no revisions for aseptic loosening and no deep infections to date. Both these revisions may be related to incorrect tissue balancing of the ßexion and extension gaps early in our learning curve with this prosthesis. These meniscal complications highlight the exacting nature of the surgical technique required for this prosthesis, particularly for the Surgeon used to implanting þxed bearing TKRñs which are more forgiving of suboptimal soft tissue balancing. Conclusions: We feel this prosthesis offers a safe and effective treatment for osteoarthritis with a good clinical outcome at 5 years with a low level of complications.

In this study we intend to evaluate the outcomes for patients with the Rotaglide mobile meniscal knee prosthesis implanted for osteoarthritis. All patients reviewed had this prosthesis implanted as a primary total knee arthroplasty in Crosshouse hospital.

The minimum follow up period was 5 years (range 5 to 8.2). Patients were assessed clinically by the junior author (CW) and the results were standardised using the Hospital for Specialist Surgery (HSS) knee score. Standard radiographs were taken in AP and lateral planes to assess for loosening using the Knee Society roentgenographic system. Case notes were then examined for evidence of complications in the peri and postoperative complications.

Sixty-five patients (71 knees) were reviewed. There was an excellent clinical outcome with HSS scores of 85 in 97.1% of patients. Two knees (2.9%) were revised, one for meniscal fracture and one for meniscal dislocation. Both these patients also attended for review and were making good progress. Both of these failures occurred early in our series and in a total of 312 knees to date there have been no other meniscal failures. No knees were revised for aseptic loosening and there have been no deep infections.

We feel this prosthesis offers a safe and effective treatment for osteoarthritis with a good clinical outcome at 5 years with a low level of complications.

Total knee arthroplasty (TKA) is a common, effective operation but postoperative infection has devastating consequences. Several papers have associated perioperative autologous transfusion with reduced infection rates. Salvaged blood may augment the inflammatory response and central within it is polymorphonuclear leukocyte (PMN). Our hypothesis was that autologous transfusion enhances PMN activity by: increased PMN transmigration to potential infection site, enhanced phagocytosis, augmented respiratory burst activity.

Our randomised controlled prospective study showed a significant increase in superoxide production by PMN of patients who received unwashed autologous transfusion supporting the clinical studies where infection rates following autologous transfusion were reduced.

Purpose: In this ongoing trial we are analysing the performance of both a fixed bearing total knee replacement and a mobile bearing total knee replacement using gait analysis and a patient-based questionnaire. We aim to find out if there is a difference in the functional performance of the two types of prosthesis.

Method: Patients are taken from the in-patient waiting list of three consultants and introduced to the trial if deemed suitable. Each patient is analysed once pre-operatively and on three occasions post-operatively (6 weeks, 3 months and 1 year) at the university gait analysis laboratory. At each visit various anthropological measurements are recorded and the patient fills in an “Activities of Daily Living” questionnaire. After calibration and measurement of the passive range of motion of both knees each patient has their gait analysed over a series of six walks using a standard 5 camera system with skin marker clusters, the kinematic data from this is supplemented with force-plate recordings and video analysis of each set of walks. Data is recorded for both of the patient’s knees. The staff in the gait analysis laboratory are blinded as to which prosthesis has been used for each patient in an effort to eliminate bias.

We present our methodology and some preliminary results.