Abstract

Introduction

Topical diclofenac has proven efficacy and safety in the management of osteoarthritic pain. Its therapeutic efficacy is dependent on its ability to deliver pharmacodynamically active concentrations to the underlying tissues in the affected joint. However, the disposition of topical diclofenac is not fully characterized, and no studies have been performed using diclofenac diethylamine 2.32% gel.

We report on the 5 year results of a randomized study comparing TKR performed using conventional instrumentation versus electromagnetic computer-assisted surgery.

This study analysed patient reported outcome measures (PROMs) at 5 years utilising the American Knee Society Score (AKSS), Oxford Knee Score (OKS), the Short Form 36 score and range of motion (ROM). Of the 200 patients enrolled 125 completed 5 year follow up, 62 in the navigated group and 63 in the conventional group. There were 28 deceased patients, 29 withdrawals and 16 lost to follow-up.

There was improvement in clinical function in most PROMs from 1-5 year follow up across both groups. OKS improved from a mean of 26.6 (12–55) to 35.1 (5–48). AKSS increased from 75.3 (0–100) to 78.4 (−10–100), SF36 from 58.9 (2.5–100) to 53.2 (0–100). ROM improved by an average 7 degrees from 110 degrees to 117 degrees (80–135). There was no statistically significant difference in PROMs between the groups at 5 years.

Patients undergoing revision surgery were identified from the dataset and global PACS. There were no revisions within 5 years in the navigated group and 3 revisions in the conventional group, two for infection and one for mid-flexion instability, giving an all cause revision rate of 3.06% at 5 years for this group.

There appears to be no significant advantage in clinical function for patients undergoing TKR for OA of the knee with electromagnetic navigation when compared to conventional techniques. There may be an advantage in reducing early revision rates using this technology.

MOXIMED KineSpring® Knee Implant System is an Orthopaedic device designed for younger or highly active patients with osteoarthritis. The device is placed under the skin, is attached to the tibia and femur, and contains springs which help limit some of the forces that are transmitted through the knee during activities such as walking or running and thereby relieve pain that may be experienced by patients with early arthritis of the knee. The aim of this study is to determine the long term safety and efficacy of the KineSpring knee implant system.

This is a prospective case series involving two centres in Glasgow. 29 patients (mean age of 45.1 years and range 18-65 years) were recruited into the study between 2011 and 2016. The Primary outcome measure was Oxford knee score (OKS) at 2, 5 and 10 years post-operatively. Secondary outcome measures include device related complications and survival, patient reported functional outcome measures, patient satisfaction, pain levels and change in radiographic classification of osteoarthritis

At 2-year follow-up, 7 implants were removed (74.1% survival). Complications include deep infection, requiring removal in 1 patient, 2 implant failures requiring removal and one spring breakage. In comparison to pre-operative measures there was an improvement in the pain (3.58 vs. 5.20, p=0.02), stiffness (4.16 vs. 4.47, p=0.6) and OKS (32.4 vs. 36.9, p=0.03).

The KineSpring improves overall pain, stiffness and functional outcome at 2 years following surgery, however there was a high rate of removal and further long-term follow up analysis is required regarding its effectiveness.

Objectives

Tranexamic acid (TXA) is an anti-fibrinolytic medication commonly used to reduce perioperative bleeding. Increasingly, topical administration as an intra-articular injection or perioperative wash is being administered during surgery. Adult soft tissues have a poor regenerative capacity and therefore damage to these tissues can be harmful to the patient. This study investigated the effects of TXA on human periarticular tissues and primary cell cultures using clinically relevant concentrations.

Tranexamic acid (TXA) is an anti-fibrinolytic medication commonly used to reduce peri-operative bleeding. Increasingly, topical administration as an intra-articular injection or peri-operative wash is being administered at concentrations between 10–100mg/ml. This study investigated effects of TXA on human periarticular tissues and primary cell cultures using clinically relevant concentrations.

Tendon, synovium and cartilage obtained from routine orthopaedic surgeries were used ex vivo or cultured for in vitro studies using various concentrations of TXA. They were stained with 5-chloromethylfluorescein diacetate and propidium iodide and imaged using confocal microscopy to identify the proportion of live and dead cells. The in vitro effect of TXA on primary cultured tenocytes, synovial like fibroblast (FLS) cells and chondrocytes was investigated using cell viability assays (MTT), fluorescent microscopy and multi-protein apoptotic arrays for cell death.

There was significant (p<0.01) increase in cell death in all tissue treated with 100mg/ml TXA, ex vivo. MTT assays revealed significant (p<0.05) decrease in cell viability following treatment with 50 or 100mg/ml of TXA within 4 hours of all cell types cultured in vitro. Additionally, there was significant (p<0.05) increase in cell apoptosis detected by fluorescent microscopy within 1 hour of exposure to TXA. Furthermore, multi-protein apoptotic arrays detected increased apoptotic proteins within 1 hour of TXA treatment in tenocytes and FLS cells.

Our study provides evidence of TXA cytotoxicity to human peri-articular tissues ex vivo and in vitro at concentrations and durations of treatment routinely used in clinical environments. Clinicians should therefore show caution when considering use of topical TXA administration.

Cephalasporin antibiotics have been commonly used for prophylaxis against surgical site infection. To prevent Clostridium difficile, the preferential use of agents such as flucloxacillin and gentamicin has been recommended. The aim of this study was to investigate the bone penetration of these antibiotics during hip and knee arthroplasty, and their efficacy against Staphylococcus aureus and S. epidermidis.

Bone samples were collected from 21 patients undergoing total knee arthroplasty (TKA) and 18 patients undergoing total hip replacement (THA). The concentration of both antibiotics was analysed using high performance liquid chromatography. Penetration was expressed as a percentage of venous blood concentration. The efficacy against common infecting organisms was measured using the epidemiological cut-off value for resistance (ECOFF).

The bone penetration of gentamicin was higher than flucloxacillin. The concentration of both antibiotics was higher in the acetabulum than the femoral head or neck (p=0.007 flucloxacillin; p=0.021 gentamicin). Flucloxacillin concentrations were effective against S. aureus and S. epidermis in all THAs and 20 (95%) TKAs. Gentamicin concentrations were effective against S.epidermis in all bone samples. Gentamicin was effective against S. aureus in 11 (89%) femoral samples. Effective concentrations of gentamicin against S. aureus were only achieved in 4 (19%) femoral and 6 (29%) tibial samples in TKA.

Flucloxacillin and gentamicin was found to effectively penetrate bone during arthroplasty. Gentamicin was effective against S. epidermidis in both THA and TKA, while it was found to be less effective against S. aureus during TKA. Bone penetration of both antibiotics was less in TKA than THA.

Unicompartmental knee arthroplasty (UKA) has been gaining popularity in recent years due to its perceived benefits over total knee arthroplasty (TKA), such as greater bone preservation, reduced operating-room time, better post-operative range of motion and improved gait. However there have been failures associated with UKA caused by misalignment of the implants that have lead to revisions. To improve the implant alignment a robotic guidance system called the RIO Robotic Arm has been developed by MAKO Surgical Corp (Ft. Lauderdale, FL), which is designed to give improved accuracy compared to traditional UKA using cutting jigs and other manual instrumentation.

The University of Strathclyde in association with Glasgow Royal Infirmary has undertaken the first independent RCT trial of the MAKO system against the Oxford unicompartmental knee arthroplasty – a conventional UKA used in the UK. Motion analysis was used in order to obtain a quantitative assessment of their movement. The results from a total of 51 patients (23 MAKO, 28 Oxford) that underwent a one year post-operative biomechanical assessment were investigated.

Motion analysis showed that during level walking the MAKO group achieved a higher knee excursion during the highest flexion portion of the weight bearing stage of the gait cycle (foot-strike to mid-stance) compared to the Oxford group (18.6° and 15.8° respectively). This difference was statistically significant (p-value = 0.03). Other knee excursion values that were compared were from mid-stance to terminal stance, and overall knee flexion. No statistically significant differences were seen in either of these measurements. A subsequent comparison of both MAKO and Oxford groups with a matched normal cohort (50 patients), demonstrated that there wasn't a statistically significant difference between the MAKO group and the normal knees during mean knee excursion from foot-strike to mid-stance (18.6° and 19.5° respectively, p-value 0.36). However the Oxford group, with a lower knee excursion was found to be significantly different to our normal control group (15.8° and 19.5° respectively, p-value < 0.001).

This suggests that the robotic-assisted knees behaved more similarly to normal gait during this phase of the gait cycle than those of the conventional group. While significant differences in gait were found between the Oxford and MAKO groups, further work is required to determine if this results in improved knee function that is perceptible to the patient.

The number of primary Total Knee Arthroplasty (TKA) and primary Total Hip Arthroplasty (THA) procedures carried out in England and Wales is increasing annually. The British Orthopaedic Association guidelines for follow up currently differ for patients with TKA and THA. In THA the BOA recommends that Orthopaedic Data Evaluation Panel (ODEP) 10A rated implants should be followed up in the first year, once at seven years and three yearly thereafter. The BOA guidelines for TKA minimum requirement is radiographs at 5 years and each five years thereafter. Few studies have investigated if early follow up affects patient management following total hip and knee arthroplasty

We carried out a retrospective review of all revision procedures carried out in our institution between April 2010 to April 2013. The medical notes and radiographs for each patient were examined to determine the operative indications and patients symptoms. 92 knee revisions and 143 hip revisions were identified. Additionally we retrospectively reviewed the outcome of 300 one year routine arthroplasty follow up appointments.

The mean time of hip revision was 8.5years (range 0 to 27years) and 5.6years (range 0 to 20years) for knee revisions. The commonest cause for revision was aseptic loosening associated with pain in 49 (53%) of knee revision patients and 89 (63%) of hip revisions. Infection accounted for 26 (28%) knee revisions and 16 (12%) hip revisions. Only 1% of hip and knee revisions was carried out in asymptomatic patients with aseptic loosening.

We did not identify any cases were a patients management was altered at the routine arthroplasty review clinic and none were referred on for further surgical treatment. The findings of our study suggest there is no evidence for a routine one year arthroplasty review and revisions were carried out in asymptomatic patients in 1% of patients.

To validate the Modified Forgotten Joint Score (MFJS) as a new patient-reported outcome measure (PROM) in hip and knee arthroplasty (THR/TKR) against the UK's gold standard Oxford Hip and Knee Scores (OHS/OKS).

The MFJS is a new assessment tool devised to provide a greater discriminatory power, particularly in well performing patients. It measures an appealing concept; the ability of a patient to forget about their artificial joint in everyday life.

Postal questionnaires were sent out to 400 THR and TKR patients who were 1–2 years post-op. The data collected from the 212 returned questionnaires was analysed in relation to construct and content validity. 77 patients took part in a test-retest repeatability assessment.

The MFJS proved to have an increased discriminatory power in high-performing patients in comparison to the OHS and OKS, highlighted by its more normal frequency of distribution and reduced ceiling effects. 30.8% of patients (n=131) achieved excellent OHS/OKS scores of 42–48 this compared to just 7.69% of patients who achieved a proportionately equivalent MFJS score of 87.5–100. The MFJS proved to have an increased test-retest repeatability based upon its intra-class correlation coefficient of 0.97 compared to the Oxford's 0.85.

The MFJS provides a more sensitive tool in the assessment of well performing hip and knee arthroplasties in comparison to the OHS/OKS. The MFJS tests the concept of awareness of a prosthetic joint, rather than pain and function and therefore should be used as adjunct to the OKS/OHS.

Decreased oxygenation and delayed wound healing may negate the advantages of using a medial parapatellar incision in Total Knee Replacement. Tissue biochemical and blood flow data are not currently available in the literature.

20 patients were included in the study and randomised to midline or medial parapatellar skin incision groups, being supervised by one of 3 Consultant surgeons. Cutaneous blood flow was measured using a Speckle Contrast Blood Perfusion Imager at pre-operative and Days 1 & 3 post-operative intervals. Interstitial fluid measurements for lactate, pyruvate, lactate/pyruvate ratio and glucose were obtained from subcutaneous catheters with a dialysis membrane. Pre-operative samples were obtained from a catheter inserted into the prospective lateral wound edge. A catheter inserted after wound closure supplied dialysates at 0.5, 1, 2, 4, 6, 12 and 24-hour intervals. One catheter was corrupted on insertion; therefore the patients with biochemical data numbered 19.

Cutaneous blood flow improved over the 3 post-operative days in both types of incision and both sides, the medial retaining comparatively better flow. At Day 3, the parapatellar incision group displayed better flow on both sides of the wound. The concentration of lactate was highest in the parapatellar incision group of patients at all intervals. Pyruvate concentrations did not appear to differ across the incision types. Similarly, glucose concentrations did not appear to differ until after 4 hours, when higher concentrations were recorded in the midline group. Lactate/pyruvate ratio appeared to be notably greater in the parapatellar incision group. Plotting change in blood flow relative to change in lactate concentration demonstrated an increase in lactate as flow deteriorates.

The study findings suggest medial parapatellar incisions have increased anaerobic metabolites due to tissue hypoperfusion. Previous studies have demonstrated decreased oxygen tension in lateral based flaps and more recently the medial to lateral arterial anatomy has been demonstrated.

The purpose of this study was to evaluate the effect of body mass index (BMI) on patients undergoing primary total knee arthroplasty for osteoarthritis. Data was collected on 664 patients at 4 centres all of whom received a Depuy PFC Sigma prosthesis. Data collected included patient demographics, Oxford Knee Score (OKS), American Knee Society Score, SF-12, complications of surgery and the need for revision.

14% of patients had a BMI<25, 35% were overweight (BMI-25–30), 32% suffered from Grade 1 obesity (BMI-30–35) and 19% had grade 2 obesity (BMI>35). Obese patients were more likely to be female, have a higher ASA grade, present at a younger age and do sedentary work or no work at all. Pre-operative Oxford knee score was significantly worse in the BMI>35 group (p<0.001).

After surgery there was a significant improvement in functional outcome measures at 5 years post-operatively with all BMI groups improved by an average of 18 or 19 points in the OKS. However because those patients with high BMI have poorer pre-operative Oxford scores their post-operative scores were lower compared to patients with a normal BMI. Similar findings were noted with range of motion of the knee joint.

Overall complication rates were found to be significantly higher in obese patients and both revision surgery and deep infection rates increased stepwise with increasing BMI levels.

Deep Infection rates were as follows: BMI<25 0%, BMI-25–30 1.3%, BMI-30–35 1.4%, BMI-35–40 3.2% and BMI>40 6.1%.

Revision rates were as follows: BMI<25 0%, BMI-25–30 0.9%, BMI-30–35 0.9%, BMI-35–40 3.2% and BMI>40 6.1%.

Although obese patients with knee osteoarthritis do benefit from joint arthroplasty, they suffer from an increased rate of complications and need for revision surgery.

The Medial Patellofemoral Ligament (MPFL) is the main restraining force against lateral patellar displacement. It is often disrupted following patellar subluxation or dislocation. MPFL reconstruction is frequently performed when conservative management fails and the patient experiences recurrent patellar dislocation. Various MPFL reconstruction procedures have been described in the literature and reported outcomes are encouraging. This study analyses the radiographic outcomes following MPFL reconstruction.

From January 2006 to January 2011, 76 consecutive patients (80 knees) with patellar recurrent dislocation underwent medial patellofemoral ligament reconstruction in three large teaching hospitals. Mean follow-up was 31.8 months (range, 13–72). Semitendinosus and gracilis autografts were used for the reconstruction and all procedures were carried out by the senior authors (WL, BR, CW, MB).

Plain radiographs (Anteroposterior (AP), Lateral and Skyline) performed preoperatively and postoperatively were used to compare the sulcus angle, congruence angle, lateral patellofemoral angle, trochlear dysplasia (Dejour classification), trochlear boss height and patellar height (Caton-Deschamps ratio). Plain radiographs (Lateral) performed postoperatively were used to evaluate the femoral tunnel placement used for MPFL reconstruction.

The sulcus angle improved from 143.2° (122.9–157.7) to 139.3° (115.7–154.6) and the congruence angle improved from 26.7° (−17.5–82.6) to 0.26° (−35.3–7.8). The lateral patellofemoral angle was 7.99° (3.2–19.2) preoperatively and 9.02° (3.2–18.2) postoperatively. The Caton-Deschamps ratio was 1.2 (1.0–1.5) preoperatively and 1.0 (0.8–1.1) postoperatively. Using the Dejour classification of trochlear dysplasia, all preoperative radiographs were considered to be grade C or D and all postoperative radiographs were considered to be grade A or B. Trochlear boss height was 5.9mm (1.8–11.6) preoperatively and 4.7mm (1.6–6.9) postoperatively. 59% of the femoral tunnels were considered to be in a good position on postoperative radiographs.

This study displayed a significant improvement in postoperative radiographic parameters, demonstrating the importance of anatomic restoration when performing MPFL reconstruction.

Time analysis from video footage gives a simple outcome measure of surgical practice against a measured model of use. The added detail that can be produced, over simply recording the usual surgical process data such as tourniquet times, allows us to identify and time the sequence of surgical procedures as stages, to describe issues, and the identification of idiosyncratic behaviours for review and comparison.

Makoplasty (Mako surgical corp. FL, US) partial knee operation times were compared using this technique with those from the Oxford (Biomet, IN, US) partial knee. Three experienced surgeons were observed over 19 Makoplasty procedures ([Consultant 1] 11, [Consultant 2] 5, [Consultant 3] 3) and 2 experienced surgeons over 11 Oxford partial knee procedures ([Consultant 1] 5, [Consultant 2] 6). Times were refined into separate stages that defined the major operative steps of both the Makoplasty and Oxford processes as used by the surgical team at the Glasgow Royal Infirmary, UK. The videos were reviewed for start and stop times for pre-defined actions that would be expected to be observed during each surgical process and from these stage lengths were calculated. For both the Oxford and Mako system 12 comparable stages were identified for comparison and the timing of the various episodes was tested for statistical significance using a Two-Sample, two tail, t-Test. assuming Equal Variances. [Stages: 1. Setup time, 2. Patient on table, 3. Skin incision, 4. Joint Prep, 5. Robot registration (Not in Oxford), 6. Tibial resection, 7. Femoral resection, 8. Trials, 9. Finishing, 10. Cementing and Washout, 11. Closure and dressing, 12. Off table]

The MAKOplasty procedures were on average longer than Oxfords by 27 minutes. This can largely be accounted for in the additional setup stage 4, where in addition to the usual joint preparation taking a couple of minutes approximately 17 minutes were spent in the MAKO cases undertaking image registration and in stage 5 where nearly five minutes were spent in setting up the robot in the MAKO cases.

In conclusion while operative times fell for the Makoplasties across the learning curve they remained elevated once the plateau was reached. It should be remembered that the surgeons had much less experience with the Makoplasty procedure and were undertaking a randomised clinical trial of outcome and hence were not minded to perform the surgery quickly but to the best of their ability and that this may account for some of the elongated surgical time. Indeed other Makoplasty surgeons report an average surgical time of 30–45 minutes per case and 6 cases per day. What is striking is that the additional steps of registration and robot positioning account for a large proportion of the differences and these are mitigated to some extent by quicker trialling of the implant and finishing of the cuts suggesting more confidence in the suitability of the cut surfaces. There is clearly a need to reduce the registration time to produce more cost effective surgeries.

Total knee arthroplasty (TKA) has been established as a successful procedure for relieving pain and improving function in patients suffering from severe knee osteoarthritis for several decades now. It involves removing bone from both the medial and lateral compartments of the knee and sacrificing one or both of the cruciate ligaments. This in turn is likely to have an impact on the patients' functional outcome. In subjects where only one compartment of the knee joint is affected with osteoarthritis then unicondylar knee arthroplasty (UKA) has been proposed as an alternative procedure to TKA. This operation preserves the cruciate ligaments and removes bone only from the affected side of the joint. As a result there is the possibility of an improved functional outcome post surgery. UKA has been associated with faster recovery, good functional outcome in terms of range of motion and it is bone sparing compared to TKA. However, the biggest obstacle to UKA success is the high failure rates.

The aim of this study was to compare the functional outcome of computer navigated TKA (n=60) and UKA (n=42) patients 12 month post operation using flexible electrogoniometry. Flexible electrogoniometry was used to investigate knee joint kinematics during gait, slopes walking, stair negotiation, and when using standard and low chairs. Maximum, minimum and excursion knee joint angles were calculated for each task.

The biomechanical assessment showed statistically significant improvements in the knee kinematics in terms of maximum (p<0.0004) and excursion (p<0.026) knee joint angles in the UKA patient group compared to the navigated TKA group for each of the functional tasks. There was no statistically significant difference between the minimum knee joint angles during these functional tasks (p>0.05).

Therefore, UKA patients were showed to have a significantly better functional outcome in terms of the maximum knee joint angle during daily tasks. A limitation of this study is that it compares two cohorts rather than two randomised groups. It is expected that UKA patients will have a better functional outcome. Our results suggest that for patients with less severe knee osteoarthritis, UKA may offer a better functional outcome than the more common surgical option of TKA. The recent advancements in computer assisted and robotic assisted knee arthroplasty has the possibility to improve the accuracy of UKA and therefore led to the increase in confidence and in usage in a procedure which has the potential to give patients a superior functional outcome.

To evaluate if young patients have a poorer functional outcome following Total Knee Arthroplasty surgery.

Database of 700 consecutive Total Knee Arthroplasty patients from Scotland, UK was collected with Oxford Knee scores and American Knee Society Scores both pre-operatively and at sequential follow up reviews (PFC database, DePuy). Complication data was also collated. Patients were then age stratified into below 55, 56–64, 65–74 and over 75 groups. Analysis was performed using General Linear Model ANOVA (Minitab v10) comparing functional score change between pre operative and 2 year score data.

No statistical difference was identified between the patient age groups and change in functional outcome scores (AKSS p=0.994; OKS p=0.368). All groups showed an improvement in functional scores over the 2 year period using both patients assessed (OKU) and physician scored outcomes (AKSS). There was no statistical difference in revision or infection rates.

Recent data has suggested higher revision and infection rates in young patients undergoing Total Knee Arthroplasty (Scottish Arthroplasty Report 2012). The data from the PFC database does not show any change in infection or revision rates within this sample population and the data does also not support any variance in change in functional outcome with all groups showing improvement following TKA. The findings may be limited due to sample size of 700 patients.

To validate the Modified Forgotten Joint Score (MFJS) as a new patient-reported outcome measure (PROM) in hip and knee arthroplasty against the UK's gold standard Oxford Hip and Knee Scores (OHS/OKS).

The original Forgotten Joint Score was created by Behrend et al to assess post-op hip/knee arthroplasty patients. It is a new assessment tool devised to provide a greater discriminatory power, particularly in the well performing patients. It measures an appealing concept; the ability of a patient to forget about their artificial joint in everyday life. The original FJS was a 12-item questionnaire, which we have modified to 10-items to improve reliability and missing data.

Postal questionnaires were sent out to 400 total hip/knee replacement (THR/TKR) patients who were 1–2 years post-op, along with the OHS/OKS and a visual pain analog score. The data collected from the 212 returned questionnaires (53% return rate) was analysed in relation to construct and content validity. A sub-cohort of 77 patients took part in a test-retest repeatability study to assess reliability of the MFJS.

The MFJS proved to have an increased discriminatory power in high-performing patients in comparison to the OHS and OKS, highlighted by its more normal frequency of distribution and reduced ceiling effects in the MFJS. 30.8% of patients (n=131) scored 42–48 (equivalent to 87.5–100 in the MFJS) or more in the OKS compared to just 7.69% in the MFJS TKR patients. The MFJS proved to have an increased test-retest repeatability based upon its intra-class correlation coefficient of 0.968 compared to the Oxford's 0.845.

The MFJS provides a more sensitive tool in the assessment of well performing hip and knee arthroplasties in comparison to the OHS/OKS. The MFJS tests the concept of awareness of a prosthetic joint, rather than pain and function and therefore should be used as adjunct to the OKS/OHS.

A retrospective analysis was carried out to determine the influence of pre-existing spinal pathology on the outcome of Total Knee Replacement surgery. Data was collected from 345 patients who had undergone Total Knee Replacement, at four centres in the UK, between 2000 and 2007. Oxford Knee Scores (OKS), American Knee Society Scores (AKSS) and SF-12 questionnaires were recorded prospectively. Data was collected pre-operatively and then post-operatively at 3 months, 1 year and 2 years. Patients were divided into those with (n=40) and without a history of low back pain (n=305). In addition to determining the influence of low back pain on outcome after Total Knee Replacement we also examined the influence of concomitant hip and ankle pathology in the same cohort of patients.

OKS scores were significantly worse for patients with symptomatic low back pain at 3 (p=0.05), 12 (p=0.009) and 24 months (p=0.039) following surgery. SF-12 physical scores followed a comparable pattern with significance demonstrated at 3 (p=0.038), 12 (p=0.0002) and 24 months (p=0.016). AKSS followed a similar pattern, but significance was only reached at 1 year (p=0.013). The mental component of the SF-12 measure demonstrated a significant improvement in patients' mental health post-operatively for patients with no history of low back pain. In contrast patients with low back pain showed no improvement in mental health scores post-operatively.

In contrast to low back pain, hip and ankle pathology had no statistically significant detrimental effect on the outcome of Total Knee Replacement surgery.

This study demonstrates that low back pain significantly affects the functional outcome after Total Knee Replacement surgery and that patients with low back pain show no improvement in mental health post-operatively.

Deep surgical infections are a serious complication of total knee arthroplasty (TKA). Various protocols exist for treating these infections, each with its own advocates. In this series we report the one to five year follow-up of infected TKA that were treated with a two-stage revision knee replacement at the Glasgow Royal Infirmary between December 2003 and March 2009.

48 patients were identified from the hospital database. 6 of these were excluded as they did not meet the stipulated infection criteria. Another patient was excluded as no notes were available thereby the infection status could not be determined. Another 8 patients were excluded as these only had a first stage.

33 patients (16 male) average age 67y (49–88) met the inclusion criteria. Mean BMI was of 31.62 (19–47) and 8 patients suffered from rheumatoid arthritis. At presentation, the median for the ESR, CRP and WCC were 70.5, 133 and 8.5 respectively. The infective organism was identified in 22 patients. Following the first stage, the patients were treated with antibiotics (initially intravenous followed by oral) for an average of 11.8 weeks (4–52 weeks). This procedure failed to eliminate the infection in 6 patients (18.18%) who had further re-admissions for infection of the affected prosthesis. The resultant success rate is of over 80% which is comparable to literature data (success rates of 41% to 96% quoted). For these patients, the average time to review was 25.13 months (12–67months). At review these patients had a mean extension of 2.17° (0–10°) and a mean flexion of 98.26 (70–120°). These patients were all satisfied with their outcome.

Our results show a high successful rate of elimination of infection when a two-stage revision is used for infected knee prosthesis with over 80% of patients free of infection.

Unicompartmental knee arthroplasty (UKA) has been gaining popularity in recent years due to its perceived benefits over total knee replacements, such as greater bone preservation, reduced operating-room time, better postoperative range of motion and improved gait. However there have been failures associated with UKA caused by misalignment of the implants.

To improve the implant alignment a robotic guidance system called the RIO Robotic Arm has been developed by MAKO Surgical Corp (Ft. Lauderdale, FL). This robotic system provides real-time tactile feedback to the surgeon during bone cutting, designed to give improved accuracy compared to traditional UKA using cutting jigs and other manual instrumentation.

The University of Strathclyde in association with Glasgow Royal Infirmary has undertaken the first independent Randomised Control Trial (RCT) of the MAKO system against the Oxford UKA – a conventional UKA used in the UK. The trial involves 139 patients across the two groups.

At present the outcomes have been evaluated for 30 patients. 14 have received the MAKO unicompartmental knee arthroplasty and 16 the Oxford UKA. Both groups were seen 1 year post-operatively. Kinematic data was collected while subjects completed level walking using a Vicon Nexus motion analysis system. Three-dimensional hip, knee and ankle angles were compared between the two arthroplasty groups.

Our initial findings indicate that hip and ankle angles show no significant statistical difference, however there is a significant difference (p < 0.05) in the knee angles during the stance phase of gait. Data shows higher angles achieved by the MAKO group over the Oxford.

It would appear from our early findings that the MAKO RIO procedure with Restoris implants gives at least comparable functional outcome with the conventional Oxford system and may prove once our full sample is available for analysis to produce better stance phase kinematics with a more active gait pattern than the conventional Oxford procedure.

Further work includes analysing the data obtained from the patients in a number of other activities. These include a full biomechanical analysis of ascending and descending a flight of stairs, sit to stand and a deep knee lunge. The high demand/high flexion tasks in particular may reveal if there's an advantage to using the MAKO procedure over the Oxford. If there is a direct correlation between alignment and patient function then this effect could be more significant in the more demanding patient tasks.