A pragmatic, multicentre, parallel-group, randomised controlled trial to determine whether the intervention is superior to comparator 20 NHS HospitalsAbstract
Design
Setting
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. This study investigated the penetration of topical diclofenac into knee synovial tissue and fluid and evaluated relative exposure in the knee versus plasma. In this phase 1, double-blind, placebo-controlled steady-state multicenter pharmacokinetic study, patients scheduled for arthroplasty to treat knee OA were randomly assigned 2:1 to 4 g diclofenac/placebo gel, applied to the affected knee every 12 hours for 7 days pre-surgery. Diclofenac concentrations were measured in synovial tissue, fluid, and plasma ≥12 hours after last application. Adverse events (AEs) were evaluated. Diclofenac concentrations were assayed by validated high-performance liquid chromatography and tandem mass spectrometry.Introduction
Methods
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.
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. Tendon, synovium, and cartilage obtained from routine orthopaedic surgeries were used for Objectives
Methods
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.
To investigate the bone penetration of intravenous antibiotic
prophylaxis with flucloxacillin and gentamicin during hip and knee
arthroplasty, and their efficacy against Bone samples from the femoral head, neck and acetabulum were
collected from 18 patients undergoing total hip arthroplasty (THA)
and from the femur and tibia in 21 patients during total knee arthroplasty
(TKA). The concentration of both antibiotics in the samples 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 against
both the minimum inhibitory concentration 50, and the more stringent epidemiological
cutoff value for resistance (ECOFF).Aims
Patients and Methods
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.
The aim of this study was to determine if a change
in antibiotic prophylaxis for routine hip and knee replacement was
associated with an increased risk of acute renal impairment. We identified 238 patients (128 knees and 110 hips) who had received
a single prophylactic dose of 1.5 g cefuroxime before joint replacement.
We compared them with prospectively collected data from 254 patients
(117 knees and 137 hips) who received a single prophylactic dose
of 2 g flucloxacillin and a height- and gender-determined dose of
gentamicin. The primary outcome measure was any new renal impairment
as graded by clinically validated criteria. We identified four patients (1.69%) in the cefuroxime group who
developed renal impairment. All four had mild impairment and all
renal function was normal by the third post-operative day. The incidence
of new-onset renal impairment was significantly higher in the flucloxacillin-and-gentamicin
group at 9.45% (24 patients) (p <
0.001). Three of these patients
remained with acute renal impairment after a week, although the
serum creatinine levels in all subsequently returned to normal. Cite this article:
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 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.
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 ( 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.
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.
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.
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.
The longitudinal midline and medial-parapatellar incision are commonly used in Total Knee Arthroplasty (TKA). Medial-parapatellar incision n offers a smaller wound, avoids creation of thin skin flaps and easier exposure in obese patients. This incision creates a lateral skin flap which may be subject to poor blood supply and delayed wound healing. We undertook a Randomised Controlled Trial (n=20) comparing midline and medial-parapatellar incisions. Cutaneous blood-flow was measured using a Doppler Imager. Interstitial fluid measurements for lactate, pyruvate, lactate/pyruvate ratio and glucose were obtained from subcutaneous microdialysis catheters. Wound cosmesis was graded and skin sensation tested. Immediately post-op there was no significant difference in subcutaneous blood flow, but by day 3 patients with medial-parapatellar incisions showed greater bloodflow than midline incisions, particularly on the medial side (387 vs 278units p=0.148). At both day 1 and 3 post-op the lateral flap of the medial parapatellar incision showed decreased blood flow compared to the medial side, though these failed to reach significance. In contrast the midline incision showed no discernable difference in blood flow between the medial and lateral flaps. Concentrations of subcutaneous glucose increased from 4 hours post-op in the midline group, returning to baseline by 24hours. In contrast, the parapatellar group remained at base line throughout. Lactate concentrations increased over time in both groups peaking at 12hours post-op. No difference was noted between incision types with regard to wound cosmesis. We conclude that the use of a medial-parapatellar incision results in only minimal biochemical changes, which are unlikely to alter wound healing. Medial-parapatellar incision is therefore a safe alternative to a midline incision and can be utilised in appropriate complex cases to aid surgical exposure.
This RCT compared electromagnetic (EM) navigated and conventional total knee arthroplasty (TKA) in terms of clinical and functional outcomes. 200 patients (navigated=102, conventional=98) were recruited. Oxford Knee Scores (OKS) and the American Knee Society Score (AKSS) were recorded pre operation, 3 and 12 months after surgery. Post operative (coronal, sagittal and rotational) alignment was analysed from 3D CT scans taken 3 months after surgery. An objective functional assessment was completed using electrogoniometry on a sub group (navigated=60, conventional=57) at 12 months post surgery. The EM group showed statistically significantly improved OKS (p=0.04) and AKSS (p=0.03) scores at 3 months post operation. However at 12 months post surgery there was no difference between the two groups. At the 1 year follow up it was reported that 9% of the navigated compared to 14% of the conventional group were dissatisfied with their surgical outcome. The mechanical axis alignment of 90% of the navigated group was within 3 degrees of neutral compared to 84% of the conventional group. Although all alignment parameters except for tibial rotation was improved in the navigated group they did not reach significance apart from femoral slope alignment (p=0.01). There was no statistically difference between the surgical groups in terms of the maximum, minimum and excursion knee joint angles during 12 functional activities. Only the knee kinematic function cycles for level walking resulted in statistically significant higher knee joint angles during 55–70% of the gait cycle in the navigated group. Knee alignment was better restored following EM navigated TKA relative to conventional TKA, but the difference was not significant. The EM group showed greater clinical and functional improvements at early follow-up; however this difference was not sustained at 12 months. The EM group reported minimal gait improvements. Proving cost-effectiveness for navigation systems in TKA remains a challenge.
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.
The aim of this study was to determine the influence of electromagnetic (EM) navigation in total knee arthroplasty (TKA) on post operative function. In this double blinded randomised control trial, patients with osteoarthritis either received TKA using conventional techniques (n = 49) or EM navigation (iNav Portable Navigation System, Zimmer Orthopaedics) (n = 52). All of the patients were reviewed in the Outcomes Clinic at 3 and 12 months. At 12 months post operation the patients completed an objective biomechanical functional assessment using flexible electrogoniometers, which recorded dynamic knee kinematics during daily activities. Knee joint flexion and extension moments were recorded at the 12 month post operation assessment. The functional assessment included validated questionnaires (Oxford Knee Score, American Knee Society Score, WOMAC Score and Short Form SF-36 Score). All patients underwent CT scanning of the implanted prosthesis to assess component alignment. Improved alignment was recorded in the navigated group. However there was no significantly significant difference between the two surgical groups in terms of the subjective questionnaire scores. The biomechanical assessment showed no statistically significant differences in the maximum, minimum or excursion knee joint angles between the two surgical groups during the 12 daily functional tasks. However, significant differences were reported in level and slope walking activities during pre-swing phase (at around 60% of the gait cycle). The navigated group had significantly higher knee joint angles during pre swing suggesting a more vigorous push off into swing phase and a more ‘normal’ gait cycle. The two surgical groups were sub divided into males and females for the strength test. The female navigated group recorded a significantly greater hamstring (p = 0.03) and quadriceps (p = 0.003) moment. There was no significant difference in hamstring or quadriceps moments between the navigated and conventional male groups. The knee kinematics and moment data suggests that the navigated group had an improved functional outcome. However the difference in the post-operation function of the two groups remains minimal despite the better alignment achieved using navigation.
Total knee arthroplasty is an established and successful operation. In up to 10% of patients who undergo total knee arthroplasty continue to complain of pain [1]. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful total knee arthroplasty. We reviewed 56 painful total knee replacements and compared these to 59 pain free total knee replacements. Datum gathered from case notes and radiographs using a prospective orthopaedic database to identify patients. The age, sex, preoperative Oxford score and BMI, postoperative Oxford score and treatments recorded. The CT information recorded was limb alignment, tibial component rotation, femoral component rotation and combined rotation.Introduction
Methods
Electromagnetic navigation versus conventional Total Knee Arthroplasty: Clinical improvements Optical and electromagnetic (EM) tracking systems are widely used commercially. However in orthopaedic applications optical systems dominate the market. Optical systems suffer from deficiencies due to line of sight. EM trackers are smaller but are affected by metal. The accuracy of the two tracker systems has been seen to be comparable1. Recent advancements in optical navigated TKA have shown improved overall limb alignment, implant placement and reduce outliers when compared to conventional TKA2-4. This study is the first RCT to compare EM and conventional TKA. Two groups of 100 patients underwent TKA using either the EM navigation system or the conventional method. Frontal, sagittal and rotational alignment was analysed from a CT scan. Clinical scores including Oxford Knee Score (OKS) and Knee/Function American Knee Society Score (AKSS) were recorded pre-op, and at 3 and 12 months post-op. 3 month data presented includes 180 patients (n = 90). The 12 months data presented includes 140 (n = 70). The two groups had similar mean mechanical axis alignments (EM 0.31o valgus, conventional 0.15o valgus). The mechanical axis alignment was improved in the EM group with 92% within +/-3o of neutral compared to 84% of the conventional group (p = 0.90). The alignment of the EM group was improved in terms of frontal femoral, frontal tibial, sagittal femoral, sagittal tibial and tibial rotation alignment. However, only the sagittal femoral alignment was significantly improved in the EM group (p = 0.04). Clinically, both TKA groups showed significant improvements in OKS and AKSS scores between both pre-op to 3 month post-op and 3 months to 12 months post-op (p<0.001). The OKS and the AKSS knee score for the EM group was significantly better at 3 months post-op (OXS p = 0.02, AKSS knee p = 0.04). However there was no difference between the groups at 12 months. The mean pre-op range of motion (ROM) for both groups was 105o. This decreased to 102o in the EM group and 99o in the conventional group at 3 months. There was a significant improvement at 12 months post-op, EM = 113o (p = 0.012) and conventional = 112o (p = 0.026). There was no significant difference in ROM between the two groups at 3 or 12 months post-op. Therefore the alignment outcome of the EM TKA group was improved compared to the conventional group. The EM group also showed clinical improvements at 3 months post-op however these were not seen again at 12 months post-op. ROM was seen to decrease at 3 months post-op but then significantly improve by 12 month post-op.
Recent advancements in optical navigated TKA have shown improved overall limb alignment, implant placement and reduced outliers compared to conventional TKA. This study represents the first RCT comparing EM navigation and conventional TKA. 3D alignment was analysed from CT scans. Clinical scores (Oxford Knee Score (OKS) and American Knee Society Score (AKSS)) were recorded at pre-op, 3 and 12 months post-op. Data presented includes 180 patients (n=90 per group) at 3 months and 140 (n=70 per group) at 12 months. The groups had similar mean mechanical axis alignments (EM 0.31° valgus; conventional 0.15° valgus). Mechanical axis alignment however was improved in the EM group with 92% within +/−3° of neutral compared to 84% of the conventional group (p=0.90). The EM group showed improved coronal and sagittal femoral alignment and improved coronal, sagittal and rotational tibial alignment, which was significant for sagittal femoral alignment (p=0.04). The OKS and AKSS scores were significantly better for the EM group at 3 months post-op (OKS p=0.02, AKSS p=0.04), but there was no difference between groups at 12 months. The mean pre-op range of motion (ROM) for both groups was 105°. This decreased at 3 months to 102° in the EM group and 99° in the conventional group, but there was a significant improvement by 12 months: EM=113° (p=0.012) and conventional=112° (p=0.026). ROM was statistically similar between groups at all assessment phases. Knee alignment was better restored following EM navigated TKA relative to conventional TKA, but the difference was not significant. The EM group showed greater clinical improvements at early follow-up; however this difference was not sustained at 12 months. ROM was seen to decrease at 3 months but then significantly improve by 12 month post-op. Proving cost-effectiveness for navigation systems in TKA remains a challenge.
Total knee arthroplasty (TKA) is an established and successful operation. However patient satisfaction rates vary from 81 to 89% 1,2,3. Pain following TKA is a significant factor in patient dissatisfaction 1. Many causes for pain following total knee arthroplasty have been identified 4 but rates of unexplained pain vary from 4 to 13.1% 5,6. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful TKA We reviewed 57 patients with an unexplained painful following TKA and compared these to a matched control group of 60 patients with TKA. Datum gathered from case notes and radiographs using a prospective database to identify patients. The CT information recorded was limb alignment, tibial component rotation, and femoral component rotation and combined rotation. The two matched cohorts of patients had similar demographics. A significant difference in tibial, femoral and combined component rotation was identified between the groups. The following mean rotations were identified for the painful and control groups respectively. Tibial rotation was 3.46 degrees internal rotation (IR) compared to 2.50 degrees external rotation (ER)(p=0.001). Femoral rotation was 2.30 IR compared to 0.36 ER(p=0.02). Combined rotation was 7.08 IR compared to 2.85 ER(p=0.001). This is the largest study presently in the literature. We have identified significant internal rotation in a patient cohort with unexplained painful TKA when compared to a matched control group. Internal rotation of the tibial component, femoral component and combined rotation was identified as a factor in unexplained pain following TKA.
Fragility fractures are an increasing cause of morbidity and mortality in the elderly population. Their association with reduced bone mineral density (BMD) is well documented. It is a reasonable assumption that hip fracture severity is linked to the magnitude of bone loss, (the lower the BMD, the more severe the fracture), however it is not known whether this correlation exists. Our aim therefore was to investigate the relationship between BMD and hip fracture severity. We reviewed 142 patients, 96 females and 46 males, mean age 74 years (49-92), who had sustained a hip fracture following a simple ground level fall. All had subsequently undergone DEXA bone scanning of the contralateral hip and lumbar spine. Fractures were classified as intra-capsular, extra-capsular or subtrochanteric, then sub-classified using the Garden, Jensen and Seinsheimer classifications respectively. They were grouped into simple (stable) or comminuted (unstable) fracture patterns. Risk factors for osteoporosis were recorded. A low hip BMD (<2.5) was associated with an increased risk of extra-capsular fracture (p=0.025). However, no association with fracture type (extra vs. intra-capsular, p>0.05) was identified with the following variables; age, gender, BMI <25, smoking, and excess alcohol intake. We did not find any statistically significant associations between fracture severity and the nine principle variables tested for: age; gender; smoking; BMI < 25; alcohol excess and low hip or lumbar BMD T or Z score <-2.5. Although the association between BMD and risk of fragility fractures is well documented, the results of this study would suggest that severity of hip fractures does not follow this correlation. Therefore, no assumption can be made about BMD of the proximal femur based on the severity of fracture observed on plain radiographs alone.
Total knee arthroplasty is an established and successful operation. In up to 13% of patients who undergo total knee arthroplasty continue to complain of pain. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful total knee arthroplasty. We reviewed 56 painful total knee replacements and compared these to 56 matched patients with pain free total knee replacements. Patients with infection, aseptic loosening, revision arthroplasties and gross coronal malalignment were excluded. Datum gathered from case notes and radiographs using a prospective orthopaedic database to identify patients. The age, sex, preoperative and postoperative Oxford scores, visual analogue scores and treatments recorded. The CT information recorded was limb alignment, tibial component rotation, femoral component rotation and combined rotation. The two cohorts of patients had similar demographics. The mean limb alignments were 1.7 degrees varus and 0.01 degrees valgus in the painful and control groups respectively. A significant difference in tibial component rotation was identified between the groups with 3.2 degrees of internal rotation in the painful group compared to 0.5 degrees of external rotation in the control group (p=0.001). A significant difference in femoral component rotation was identified between the groups with 3.8 degrees of internal rotation in the painful group compared to 1.1 degrees of external rotation in the control group (p=0.001). A significant difference in the combined component rotation was identified between the groups with 6.8 degrees of internal rotation in the painful group compared to 1.7 degrees of external rotation in the control group (p=0.001). We have identified significant internal rotation in a patient cohort with painful total knee arthroplasty when compared to a control group with internal rotation of the tibial component, femoral component and combined rotation. This is the largest comparison series currently in the literature.
Unidirectional mobile bearing knees (RP) were developed to optimise the tibio-femoral articulation in an effort to enhance function and reduce polyethylene wear. The self aligning bearing should also benefit the patello-femoral joint further improving outcome. This study was designed to assess whether these potential benefits are realised in the clinical setting. A total of 352 patients undergoing a PS PFC Sigma TKR were randomly allocated to receive either a Mobile Bearing (176 knees) or a Fixed Bearing (176 knees) tibial tray. Within each group a further randomisation for patella resurfacing versus retention was included. All knees were scored using standard tools (Oxford, AKSS, Patella Score) by independent nurse specialists. At 5 year review there had been 38 deaths (19 in each group), 5 revisions (4 fixed, 1 RP), 7 late patella resurfacings (4 fixed, 3 RP) and a small number of other patients had withdrawn, leaving 142 fixed bearing knees and 144 mobile bearing knees for evaluation.Introduction
Methods
We report a large study of 331 patients at two years post operation who were prospectively randomised to receive either a rotating platform or a fixed bearing knee replacement of an otherwise identical design. The mobile bearing total knee replacement was developed as there are theoretical benefits in that it may allow a better range of motion, better patella tracking and lower wear rates. This study was designed to see if these potential advantages are borne out in practice when using a cruciate retaining design.Summary
Introduction
Previous studies comparing cruciate retaining (CR) and cruciate sacrificing - posterior stabilised (PS) TKRs have failed to demonstrate a difference in outcomes based on numbers of patients recruited. This large study compares clinical outcomes in groups having PS and CR TKR and reports the results at 1 and 2 years post-operatively. A total of 683 patients undergoing TKR were consecutively enrolled in a prospective multi-centre study with 2 arms. In the first arm patients receiving a PS component were randomised to receive either a mobile bearing (176 patients) or fixed bearing (176 patients) implant. In the second arm, patients receiving a CR component were randomised to receive either a mobile bearing (161 patients) or fixed bearing (170 patients) implant. All patients were assessed preoperatively and at one and two years postoperatively using standard tools (Oxford, AKSS, Patellar Score) by independent nurse specialists. The data from the 2 arms of the trial were then analysed to compare differences between PS and CR implants.Introduction
Methods
The aim of the study was to assess the impact of a self aligning unidirectional mobile tibial bearing and the use of a patella button on lateral patella release rates within a knee system using a common femoral component for both the fixed and mobile variants. A total of 347 patients undergoing TKR were included in the study and randomly allocated to receive either a Mobile Bearing (171 knees) or a Fixed Bearing (176 knees) PS PFC Sigma TKR. Further sub-randomisation into patella resurfacing or retention was performed for both designs. The need for lateral patella release was assessed during surgery using the ‘no thumbs’ technique. The lateral release rate was similar for fixed bearing (9.65%) and mobile bearing (9.94%) implants (p=0.963). Patella resurfacing resulted in lower lateral release rates when compared to patella retention (5.8% vs 13.8%; p=0.0131). This difference was most marked in the mobile bearing group where the lateral release rate was 16.3% with patella retention compared to 3.5% with patella resurfacing (p=0.005).Aim
Methods and results
It is hypothesised that cruciate retention in total knee arthroplasty may result in improved kinematics of the knee by maintaining the femoral rollback seen in the normal knee, resulting in improved function. This study compares clinical outcomes in groups having PS and CR total knee arthroplasty and report the results at 1 and 2 years post-operatively.
Patients with a PS also showed a greater improvement in the AKSS knee score at 1 (p=0.0001) and 2 (p=0.001) years. Knee flexion improvement was also greater in the PS group at 1 (p=0<
0.0001) and 2 (p=0.0035) years. PS knees also achieved better outcomes in these variables in the mobile and fixed subgroups. There were no other significant differences in the scores between the two groups at any stage.
The lateral release rate was similar for fixed bearing (9%) and mobile bearing (9%) implants (p=0.95). Patella resurfacing resulted in lower lateral release rates when compared to patella retention (5.5% vs 13.5%; p=0.012). This difference was most marked in the mobile bearing group where the lateral release rate was 16% with patella retention compared to 3% with patella resurfacing (p=0.009).
The range of motion increased from an average of 96 deg. (pre-op) to an average of 109 deg. at 1 year post-op for both the fixed and mobile bearing design. The management of the patella had no effect in either group. The knee society and knee function scores increased equally for both the fixed bearing and mobile bearing knees with no differences noted.
