Imperial College London

MrAlexLiddle

Faculty of MedicineDepartment of Surgery & Cancer

Clinical Senior Lecturer in Orthopaedics
 
 
 
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Contact

 

a.liddle Website

 
 
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Assistant

 

Miss Colinette Hazel +44 (0)20 7594 2725

 
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Location

 

203Building E - Sir Michael UrenWhite City Campus

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Summary

 

Publications

Publication Type
Year
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67 results found

Davies DJ, McLean PF, Kemp PR, Liddle AD, Morrell MJ, Halse O, Martin NM, Sam AHet al., 2022, Assessment of factual recall and higher-order cognitive domains in an open-book medical school examination, Advances in Health Sciences Education, Vol: 27, Pages: 147-165, ISSN: 1382-4996

Open-book examinations (OBEs) will likely become increasingly important assessment tools. We investigated how access to open-book resources affected questions testing factual recall, which might be easy to look-up, versus questions testing higher-order cognitive domains. Few studies have investigated OBEs using modern Internet resources or as summative assessments. We compared performance on an examination conducted as a traditional closed-book exam (CBE) in 2019 (N = 320) and a remote OBE with free access to Internet resources in 2020 (N = 337) due to COVID-19. This summative, end-of-year assessment focused on basic science for second-year medical students. We categorized questions by Bloom’s taxonomy (‘Remember’, versus ‘Understand/Apply’). We predicted higher performance on the OBE, driven by higher performance on ‘Remember’ questions. We used an item-centric analysis by using performance per item over all examinees as the outcome variable in logistic regression, with terms ‘Open-Book, ‘Bloom Category’ and their interaction. Performance was higher on OBE questions than CBE questions (OR 2.2, 95% CI: 2.14–2.39), and higher on ‘Remember’ than ‘Understand/Apply’ questions (OR 1.13, 95% CI: 1.09–1.19). The difference in performance between ‘Remember’ and ‘Understand/Apply’ questions was greater in the OBE than the CBE (‘Open-Book’ * ‘Bloom Category’ interaction: OR 1.2, 95% CI: 1.19–1.37). Access to open-book resources had a greater effect on performance on factual recall questions than higher-order questions, though performance was higher in the OBE overall. OBE design must consider how searching for information affects performance, particularly on questions measuring different domains of knowledge.

Journal article

Carlos Rodriguez-Merchan E, Encinas-Ullan CA, Liddle AD, 2022, Osteochondral Allografts for Large Osteochondral Lesions of the Knee Joint: Indications, Surgical Techniques and Results, ARCHIVES OF BONE AND JOINT SURGERY-ABJS, Vol: 10, Pages: 245-251, ISSN: 2345-4644

Journal article

Edwards T, Guest B, Garner A, Logishetty K, Liddle A, Cobb Jet al., 2022, The metabolic equivalent of task score: a useful metric for comparing high functioning hip arthroplasty patients, Bone & Joint Research, ISSN: 2046-3758

Aims: This study investigates the use of the Metabolic Equivalent of Task (MET) score in a young hip arthroplasty population and its ability to capture additional benefit beyond the ceiling effect of conventional patient reported outcomes.Patients & Method: Oxford Hip Score (OHS), EuroQol-5D index (EQ-5D), and the MET were recorded in 221 primary hip arthroplasty procedures pre-operatively and at 1-year. The distribution was examined reporting the presence of ceiling & floor effects. Validity was assessed correlating the MET with the other scores using Spearman’s rank and determining responsiveness. A subgroup of 93 patients scoring 48/48 on the OHS were analysed by age, sex, BMI and pre-operative MET using the other metrics to determine if differences could be established despite scoring identically on the OHS.Results: From our electronic database of 751 hip arthroplasty procedures, 117 primary total hip and 104 hip resurfacing arthroplasty operations were included. Mean age was 59.4 ± 11.3. Post-operatively the OHS and EQ-5D demonstrate significant negatively skewed distributions with ceiling effects of 41% and 53%, respectively. The MET was normally distributed post-operatively with no ceiling effect. Weak-moderate significant correlations were found between the MET and the other two metrics. In the 48/48 subgroup, no differences were found comparing groups with the EQ-5D, however significantly higher MET scores were demonstrated for patients aged <60 (12.7 vs 10.6, p=0.008), male patients (12.5 vs 10.8, p=0.024) and those with pre-operative MET scores >6 (12.6 vs 11.0, p=0.040). Conclusion: The MET is normally distributed in patients following hip arthroplasty, recording levels of activity which are undetectable using the OHS.

Journal article

Munford M, Liddle A, Stoddart J, Cobb J, Jeffers Jet al., 2022, Total and partial knee replacement implants that maintain native load transfer in the Tibia, Bone and Joint Research, Vol: 11, Pages: 1-3, ISSN: 2046-3758

Aims:Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but the solid metal implants disrupt the natural distribution of stress and strain which can lead to bone loss over time. This generates problems if the implant needs to be revised. This study investigates whether titanium lattice UKA and TKA implants can maintain natural load transfer in the proximal tibia. Methods:In a cadaveric model, UKA and TKA procedures were performed on 8 fresh-frozen knee specimens, using conventional (solid) and titanium lattice tibial implants. Stress at the bone-implant interfaces were measured and compared to the native knee.Results:Titanium lattice implants were able to restore the mechanical environment of the native tibia for both UKA and TKA designs. Maximum stress at the bone-implant interface ranged from 1.2-3.3 MPa compared to 1.3-2.7 MPa for the native tibia. The conventional solid UKA and TKA implants reduced the maximum stress in the bone by a factor of 10 and caused >70% of bone surface area to be underloaded compared to the native tibia. Conclusions:Titanium lattice implants maintained the natural mechanical loading in the proximal tibia after UKA and TKA, but conventional solid implants did not. This is an exciting first step towards implants that maintain bone health, but such implants also have to meet fatigue and micromotion criteria to be clinically viable.

Journal article

Davies A, Lloyd T, Sabharwal S, Liddle AD, Reilly Pet al., 2022, Anatomical shoulder replacements in young patients: A systematic review and meta-analysis, Shoulder and Elbow, ISSN: 1758-5732

Introduction: Increasing numbers of young patients receive shoulder replacements. Greater information on outcomes is needed to inform implant choice. The aim of this study was to investigate the survivorship and clinical effectiveness of hemiarthroplasty and anatomical total shoulder arthroplasty (TSA) in patients younger than 65 years. Method: A systematic review was performed of MEDLINE, EMBASE, CENTRAL, The Cochrane Database of Systematic Reviews and National Joint Registry reports. The primary outcomes were implant survival and change in perioperative shoulder scores. Results: Meta-analysis of implant survivorship was performed of six studies reporting on 416 patients. Implant survival was 86.1% (72.1,100) at 10 years for hemiarthroplasty and 82.3% (64.6,100) for TSA. 20 year survival was 80.0% for hemiarthroplasty (72.5,87.4) and 75.0% (56.9,93.1) for TSA. Ten studies were included in the meta-analysis of shoulder scores, multiple instruments were used. The standardised mean difference between pre-operative and post-operative shoulder scores was 2.15 (1.95, 2.35) for TSA at 4.2–4.9 years, and 2.72 (1.98,3.47) for hemiarthroplasty at 3.8–6 years. Conclusion: Over 80% of shoulder replacements last more than 10 years, and 75% last more than 20 years. Significant improvements in shoulder scores are shown at all time points.

Journal article

Rodriguez-Merchan EC, Davidson DJ, Liddle AD, 2021, Recent Strategies to Combat Infections from Biofilm-Forming Bacteria on Orthopaedic Implants, INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES, Vol: 22

Journal article

Garner AJ, Edwards TC, Liddle AD, Jones GG, Cobb JPet al., 2021, The revision partial knee classification system: understanding the causative pathology and magnitude of further surgery following partial knee arthroplasty., Bone & Joint Open, Vol: 2, Pages: 638-645, ISSN: 2633-1462

AIMS: Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics. METHODS: Classification categories were proposed by a surgical consensus group, then ranked by patients, according to perceived invasiveness and implications for recovery. In round one, 26 revision cases were classified by the consensus group. Results were tested for inter-rater reliability. In round two, four additional cases were added for clarity. Round three repeated the survey one month later, subject to inter- and intrarater reliability testing. In round four, five additional expert partial knee arthroplasty surgeons were asked to classify the 30 cases according to the proposed revision partial knee classification (RPKC) system. RESULTS: Four classes were proposed: PR1, where no bone-implant interfaces are affected; PR2, where surgery does not include conversion to total knee arthroplasty, for example, a second partial arthroplasty to a native compartment; PR3, when a standard primary total knee prosthesis is used; and PR4 when revision components are necessary. Round one resulted in 92% inter-rater agreement (Kendall's W 0.97; p < 0.005), rising to 93% in round two (Kendall's W 0.98; p < 0.001). Round three demonstrated 97% agreement (Kendall's W 0.98; p < 0.001), with high intra-rater reliability (interclass correlation coefficient (ICC) 0.99; 95% confidence interval 0.98 to 0.99). Round four resulted in 80% agreement (Kendall's W 0.92; p < 0.001). CONCLUSION: The RPKC system accounts for all procedures which may be appropriate following partial knee arthroplasty. It h

Journal article

Edwards TC, Patel A, Szyszka B, Coombs AW, Liddle AD, Kucheria R, Cobb JP, Logishetty Ket al., 2021, Immersive virtual reality enables technical skill acquisition for scrub nurses in complex revision total knee arthroplasty., Archives of Orthopaedic and Trauma Surgery, Vol: 141, ISSN: 0344-8444

INTRODUCTION: Immersive Virtual Reality (iVR) is a novel technology which can enhance surgical training in a virtual environment without supervision. However, it is untested for the training to select, assemble and deliver instrumentation in orthopaedic surgery-typically performed by scrub nurses. This study investigates the impact of an iVR curriculum on this facet of the technically demanding revision total knee arthroplasty. MATERIALS AND METHODS: Ten scrub nurses completed training in four iVR sessions over a 4-week period. Initially, nurses completed a baseline real-world assessment, performing their role with real equipment in a simulated operation assessment. Each subsequent iVR session involved a guided mode, where the software taught participants the procedural choreography and assembly of instrumentation in a simulated operating room. In the latter three sessions, nurses also undertook an assessment in iVR. Outcome measures were related to procedural sequence, duration of surgery and efficiency of movement. Transfer of skills from iVR to the real world was assessed in a post-training simulated operation assessment. A pre- and post-training questionnaire assessed the participants knowledge, confidence and anxiety. RESULTS: Operative time reduced by an average of 47% across the 3 unguided sessions (mean 55.5 ± 17.6 min to 29.3 ± 12.1 min, p > 0.001). Assistive prompts reduced by 75% (34.1 ± 16.8 to 8.6 ± 8.8, p < 0.001), dominant hand motion by 28% (881.3 ± 178.5 m to 643.3 ± 119.8 m, p < 0.001) and head motion by 36% (459.9 ± 99.7 m to 292.6 ± 85.3 m, p < 0.001). Real-world skill improved from 11% prior to iVR training to 84% correct post-training. Participants reported increased confidence and r

Journal article

Logishetty K, Edwards TC, Subbiah Ponniah H, Ahmed M, Liddle AD, Cobb J, Clark Cet al., 2021, How to prioritize patients and redesign care to safely resume planned surgery during the COVID-19 pandemic., Bone & Joint Open, Vol: 2, Pages: 134-140, ISSN: 2633-1462

AIMS: Restarting planned surgery during the COVID-19 pandemic is a clinical and societal priority, but it is unknown whether it can be done safely and include high-risk or complex cases. We developed a Surgical Prioritization and Allocation Guide (SPAG). Here, we validate its effectiveness and safety in COVID-free sites. METHODS: A multidisciplinary surgical prioritization committee developed the SPAG, incorporating procedural urgency, shared decision-making, patient safety, and biopsychosocial factors; and applied it to 1,142 adult patients awaiting orthopaedic surgery. Patients were stratified into four priority groups and underwent surgery at three COVID-free sites, including one with access to a high dependency unit (HDU) or intensive care unit (ICU) and specialist resources. Safety was assessed by the number of patients requiring inpatient postoperative HDU/ICU admission, contracting COVID-19 within 14 days postoperatively, and mortality within 30 days postoperatively. RESULTS: A total of 1,142 patients were included, 47 declined surgery, and 110 were deemed high-risk or requiring specialist resources. In the ten-week study period, 28 high-risk patients underwent surgery, during which 68% (13/19) of Priority 2 (P2, surgery within one month) patients underwent surgery, and 15% (3/20) of P3 (< three months) and 16% (11/71) of P4 (> three months) groups. Of the 1,032 low-risk patients, 322 patients underwent surgery. Overall, 21 P3 and P4 patients were expedited to 'Urgent' based on biopsychosocial factors identified by the SPAG. During the study period, 91% (19/21) of the Urgent group, 52% (49/95) of P2, 36% (70/196) of P3, and 26% (184/720) of P4 underwent surgery. No patients died or were admitted to HDU/ICU, or contracted COVID-19. CONCLUSION: Our widely generalizable model enabled the restart of planned surgery during the COVID-19 pandemic, without compromising patient safety or excluding high-risk or complex cases. Patients classified as Urgent or P2 w

Journal article

Raymond AC, Liddle AD, Alvand A, Donaldson JR, Carrington RWJ, Miles Jet al., 2021, Clinical Outcome of Free Latissimus Dorsi Flaps for Coverage of Soft Tissue Defects in Multiply Revised Total Knee Arthroplasties, JOURNAL OF ARTHROPLASTY, Vol: 36, Pages: 664-669, ISSN: 0883-5403

Journal article

Liddle AD, 2020, CORR Insights (R): What Is the Survivorship After Hip Arthroscopy for Femoroacetabular Impingement? A Large-database Study, CLINICAL ORTHOPAEDICS AND RELATED RESEARCH, Vol: 478, Pages: 2274-2276, ISSN: 0009-921X

Journal article

Carlos Rodriguez-Merchan E, Liddle AD, 2020, Prevention of Periprosthetic Joint Infection in Total Knee Arthroplasty: Main Studies Reported Between November 2017 and January 2020, ARCHIVES OF BONE AND JOINT SURGERY-ABJS, Vol: 8, Pages: 465-469, ISSN: 2345-4644

Journal article

Davidson DJ, Spratt D, Liddle AD, 2019, Implant materials and prosthetic joint infection: the battle with the biofilm, EFORT Open Reviews, Vol: 4, ISSN: 2058-5241

• Prosthetic joint infection (PJI) is associated with poor clinical outcomes and is expensive to treat.• Although uncommon overall (affecting between 0.5% and 2.2% of cases), PJI is one of the most commonly encountered complications of joint replacement and its incidence is increasing, putting a significant burden on healthcare systems.• Once established, PJI is extremely difficult to eradicate as bacteria exist in biofilms which protect them from antibiotics and the host immune response.• Improved understanding of the microbial pathology in PJI has generated potential new treatment strategies for prevention and eradication of biofilm associated infection including modification of implant surfaces to prevent adhesion of bacteria.• Much research is currently ongoing looking at different implant surface coatings and modifications, and although most of this work has not translated into clinical medicine there has been some early clinical success.

Journal article

Al-Ani A, Bence M, Liddle AD, Ferris Bet al., 2019, Admission and treatment at a weekend is not associated with worse outcomes for patients admitted with fractured neck of femur, Trauma, Pages: 146040861878592-146040861878592, ISSN: 1460-4086

Journal article

Koo K, Liddle AD, Pastides PS, Rosenfeld PFet al., 2019, The Salto total ankle arthroplasty - clinical and radiological outcomes at five years, Foot and Ankle Surgery, Vol: 25, Pages: 523-528, ISSN: 1268-7731

BACKGROUND: Modern designs of total ankle arthroplasty (TAA) have the potential to treat symptomatic ankle OA without adversely affecting ankle biomechanics. We present the mid-term results of a modern, mobile-bearing TAA design. METHODS: TAA was performed in 50 consecutive patients (55 ankles) in an independent, prospective, single-centre series. Implant survival, patient-reported outcome measures (PROMs) and radiographic outcomes are presented at a mean of five years (range 2-10.5years). RESULTS: A total of three patients (four ankles) died and two (two ankles) were lost to follow-up. Three TAAs were revised for aseptic loosening (in two cases) or infection. Two further patients underwent reoperations, one for arthroscopic debridement of anterolateral synovitis and one for grafting of an asymptomatic tibial cyst. With all-cause revision as an endpoint, implant survival was 93.3% at five to ten years (95% CI 80.5%-97.8%). If reoperations are included this falls to 90.2% (95% CI 75.6%-96.3%) at five years. No other patient demonstrated radiographic evidence of loosening or subsidence. PROMs and satisfaction were excellent at latest follow-up. CONCLUSION: At five years, the outcomes for this design of TAA in this series were excellent, and were similar to those of previously published series from the designer centre.

Journal article

Burn E, Sanchez-Santos MT, Pandit HG, Hamilton TW, Liddle AD, Murray DW, Pinedo-Villanueva Ret al., 2018, Ten-year patient-reported outcomes following total and minimally invasive unicompartmental knee arthroplasty: a propensity score-matched cohort analysis, Knee Surgery, Sports Traumatology, Arthroscopy, Vol: 26, Pages: 1455-1464, ISSN: 0942-2056

PurposeFor patients with medial compartment arthritis who have failed non-operative treatment, either a total knee arthroplasty (TKA) or a unicompartmental knee arthroplasty (UKA) can be undertaken. This analysis considers how the choice between UKA and TKA affects long-term patient-reported outcome measures (PROMs).MethodsThe Knee Arthroplasty Trial (KAT) and a cohort of patients who received a minimally invasive UKA provided data. Propensity score matching was used to identify comparable patients. Oxford Knee Score (OKS), its pain and function components, and the EuroQol 5 Domain (EQ-5D) index, estimated on the basis of OKS responses, were then compared over 10 years following surgery. Mixed-effects regressions for repeated measures were used to estimate the effect of patient characteristics and type of surgery on PROMs.ResultsFive-hundred and ninety UKAs were matched to the same number of TKAs. Receiving UKA rather than TKA was found to be associated with better scores for OKS, including both its pain and function components, and EQ-5D, with the differences expected to grow over time. UKA was also associated with an increased likelihood of patients achieving a successful outcome, with an increased chance of attaining minimally clinically important improvements in both OKS and EQ-5D, and an ‘excellent’ OKS. In addition, for both procedures, patients aged between 60 and 70 and better pre-operative scores were associated with better post-operative outcomes.ConclusionMinimally invasive UKAs performed on patients with the appropriate indications led to better patient-reported pain and function scores than TKAs performed on comparable patients. UKA can lead to better long-term quality of life than TKA and this should be considered alongside risk of revision when choosing between the procedures.Level of evidenceII.

Journal article

Burn E, Liddle AD, Hamilton TW, Judge A, Pandit HG, Murray DW, Pinedo-Villanueva Ret al., 2018, Cost-effectiveness of unicompartmental compared with total knee replacement: A population-based study using data from the National Joint Registry for England and Wales, BMJ Open, Vol: 8, ISSN: 2044-6055

Objectives To assess the value for money of unicompartmental knee replacement (UKR) compared with total knee replacement (TKR).Design A lifetime Markov model provided the framework for the analysis.Setting Data from the National Joint Registry (NJR) for England and Wales primarily informed the analysis.Participants Propensity score matched patients in the NJR who received either a UKR or TKR.Interventions UKR is a less invasive alternative to TKR, where only the compartment affected by osteoarthritis is replaced.Primary outcome measures Incremental quality-adjusted life years (QALYs) and healthcare system costs.Results The provision of UKR is expected to lead to a gain in QALYs compared with TKR for all age and gender subgroups (male: <60 years: 0.12, 60–75 years: 0.20, 75+ years: 0.19; female: <60 years: 0.10, 60–75 years: 0.28, 75+ years: 0.44) and a reduction in costs (male: <60: £−1223, 60–75 years: £−1355, 75+ years: £−2005; female: <60 years: £−601, 60–75 years: £−935, 75+ years: £−1102 per patient over the lifetime). UKR is expected to lead to a reduction in QALYs compared with TKR when performed by surgeons with low UKR utilisation but an increase among those with high utilisation (<10%, median 6%: −0.04, ≥10%, median 27%: 0.26). Regardless of surgeon usage, costs associated with UKR are expected to be lower than those of TKR (<10%: £−127, ≥10%: £−758).Conclusions UKR can be expected to generate better health outcomes and lower lifetime costs than TKR. Surgeon usage of UKR does, however, have a significant impact on the cost-effectiveness of the procedure. To achieve the best results, surgeons need to perform a sufficient proportion of knee replacements as UKR. Low usage surgeons may therefore need to broaden their indications for UKR.

Journal article

Sanchez-Santos MT, Garriga C, Judge A, Batra RN, Price AJ, Liddle AD, Javaid MK, Cooper C, Murray DW, Arden NKet al., 2018, Development and validation of a clinical prediction model for patient-reported pain and function after primary total knee replacement surgery, Scientific Reports, Vol: 8, ISSN: 2045-2322

To develop and validate a clinical prediction model of patient-reported pain and function after undergoing total knee replacement (TKR). We used data of 1,649 patients from the Knee Arthroplasty Trial who received primary TKR across 34 centres in the UK. The external validation included 595 patients from Southampton University Hospital, and Nuffield Orthopaedic Centre (Oxford). The outcome was the Oxford Knee Score (OKS) 12-month after TKR. Pre-operative predictors including patient characteristics and clinical factors were considered. Bootstrap backward linear regression analysis was used. Low pre-operative OKS, living in poor areas, high body mass index, and patient-reported anxiety or depression were associated with worse outcome. The clinical factors associated with worse outcome were worse pre-operative physical status, presence of other conditions affecting mobility and previous knee arthroscopy. Presence of fixed flexion deformity and an absent or damaged pre-operative anterior cruciate ligament (compared with intact) were associated with better outcome. Discrimination and calibration statistics were satisfactory. External validation predicted 21.1% of the variance of outcome. This is the first clinical prediction model for predicting self-reported pain and function 12 months after TKR to be externally validated. It will help to inform to patients regarding expectations of the outcome after knee replacement surgery.

Journal article

Hexter AT, Hislop SM, Blunn GW, Liddle ADet al., 2018, The effect of bearing surface on risk of periprosthetic joint infection in total hip arthroplasty: A systematic review and meta-analysis, Bone and Joint Journal, Vol: 100B, Pages: 134-142, ISSN: 2049-4394

AimsPeriprosthetic joint infection (PJI) is a serious complication of total hip arthroplasty (THA). Different bearing surface materials have different surface properties and it has been suggested that the choice of bearing surface may influence the risk of PJI after THA. The objective of this meta-analysis was to compare the rate of PJI between metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), and ceramic-on-ceramic (CoC) bearings.Patients and MethodsElectronic databases (Medline, Embase, Cochrane library, Web of Science, and Cumulative Index of Nursing and Allied Health Literature) were searched for comparative randomized and observational studies that reported the incidence of PJI for different bearing surfaces. Two investigators independently reviewed studies for eligibility, evaluated risk of bias, and performed data extraction. Meta-analysis was performed using the Mantel–Haenzel method and random-effects model in accordance with methods of the Cochrane group.ResultsOur search strategy revealed 2272 studies, of which 17 met the inclusion criteria and were analyzed. These comprised 11 randomized controlled trials and six observational studies. The overall quality of included studies was high but the observational studies were at high risk of bias due to inadequate adjustment for confounding factors. The overall cumulative incidence of PJI across all studies was 0.78% (1514/193 378). For each bearing combination, the overall incidence was as follows: MoP 0.85% (1353/158 430); CoP 0.38% (67/17 489); and CoC 0.53% (94/17 459). The meta-analysis showed no significant difference between the three bearing combinations in terms of risk of PJI.ConclusionOn the basis of the clinical studies available, there is no evidence that bearing choice influences the risk of PJI. Future research, including basic science studies and large, adequately controlled registry studies, may be helpful in determining whether implant materials play a role in determining the ri

Journal article

Mushtaq N, Liddle AD, Isaac D, Dillow K, Gill Pet al., 2018, Patient-reported outcomes following single- and multiple-radius total knee replacement: a randomized, controlled trial, Journal of Knee Surgery, Vol: 31, Pages: 87-91, ISSN: 1538-8506

Although single-radius (SR) designs of total knee replacement (TKR) have theoretical benefits, the clinical advantage conferred by such designs is unknown. The aim of this randomized, controlled study was to compare the short-term clinical outcomes of the two design rationales. A total of 105 knees were randomized to receive either a single radius (Scorpio, Stryker; SR Group) or multiple radius (AGC, Zimmer Biomet; MR group) TKR. Patient-reported outcomes (Oxford Knee Score [OKS] and Knee Society Score [KSS]) were collected at 6 weeks, 6 months, and 1 year following surgery. No knees were revised. There was no difference in primary outcomes: OKS was 39.5 (95% confidence interval [CI]: 36.9–42.1) in the SR group and 38.1 (95% CI: 36.0–40.3) in the MR group (p = 0.40). KSS was 168.4 (95% CI: 159.8–177.0) in the SR group; 159.5 (95% CI 150.5–168.5) in the MR group (p = 0.16). There was a small but statistically significant difference in the degree of change of the objective subscale of the KSS, favoring the SR design (p = 0.04), but this is of uncertain clinical relevance. The reported benefits of SR designs do not provide demonstrable functional advantages in the short term.

Journal article

Burn E, Liddle AD, Hamilton TW, Pai S, Pandit HG, Murray DW, Pinedo-Villanueva Ret al., 2017, Choosing between unicompartmental and total knee replacement: what can economic evaluations tell us? A Systematic Review, PharmacoEconomics - Open, Vol: 1, Pages: 241-253, ISSN: 2509-4254

Background and objectivePatients with anteromedial arthritis who require a knee replacement could receive either a unicompartmental knee replacement (UKR) or a total knee replacement (TKR). This review has been undertaken to identify economic evaluations comparing UKR and TKR, evaluate the approaches that were taken in the studies, assess the quality of reporting of these evaluations, and consider what they can tell us about the relative value for money of the procedures.MethodsA search of MEDLINE, EMBASE and the Centre for Reviews and Dissemination National Health Service Economic Evaluation Database was undertaken in January 2016 to identify relevant studies. Study characteristics were described, the quality of reporting and methods assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist, and study findings summarised.ResultsTwelve studies satisfied the inclusion criteria. Five were within-study analyses, while another was based on a literature review. The remaining six studies were model-based analyses. All studies were informed by observational data. While methodological approaches varied, studies generally had either limited follow-up, did not fully account for baseline differences in patient characteristics or relied on previous research that did not. The quality of reporting was generally adequate across studies, except for considerations of the settings to which evaluations applied and the generalisability of the results to other decision-making contexts. In the short-term, UKR was generally associated with better health outcomes and lower costs than TKR. Initial cost savings associated with UKR seem to persist over patients’ lifetimes even after accounting for higher rates of revision. For older patients, initial health improvements also appear to be maintained, making UKR the dominant treatment choice. However, for younger patients findings for health outcomes and overall cost effectiveness are mixed, with th

Journal article

Liddle AD, Carlos Rodriguez-Merchan E, 2017, Evidence-based management of the knee in hemophilia, JBJS Reviews, Vol: 5, ISSN: 2329-9185

» Hemophilia is among the commonest bleeding disordersencountered in orthopaedic practice and results from an Xchromosome-linked failure of coagulation factors VIII (hemophilia A) orIX (hemophilia B).» Morbidity in hemophilia is a result of repeated hemarthroses, and theaim of orthopaedic management is to prevent these, to treat thempromptly, and to address the joint pathology that results.» Both radiosynovectomy and arthroscopic synovectomy are effectivein reducing the degree of synovitis and the number of hemarthroses,although, to our knowledge, there is little evidence that it preventsprogression to end-stage arthritis. There is substantial evidence for thesafety and effectiveness of radiosynovectomy, and this is the first lineof treatment in our practice.» In end-stage disease, total knee arthroplasty is challenging as a resultof severe contractures and is associated with a higher rate ofcomplications such as infection (7% compared with 1% to 2% inosteoarthritis) and need for blood transfusions and a higher revisionrate than that seen in total knee arthroplasty for osteoarthritis.» However, many series of total knee arthroplasty for hemophilia havenow been published, and excellent results can be gained in terms ofpain relief and quality of life.

Journal article

Carlos Rodriguez-Merchan E, Liddle AD, 2017, Pathogenesis and treatment options for hemophilic synovitis, Expert opinion on orphan drugs, Vol: 5, Pages: 173-179, ISSN: 2167-8707

Introduction: Hemophilia is characterized by recurrent bleeding episodes, most commonly in the knees, elbows and ankles. Repeated hemarthroses lead to synovial hypertrophy and a vicious cycle of chronic synovitis arises, leading to destruction of the joint.Areas covered: This article covers the pathogenesis of chronic hemophilic synovitis and its treatment by means of different types of synovectomy.Expert opinion: Both radiosynovectomy (RS) and arthroscopic synovectomy considerably improve the frequency of bleeding episodes. RS is the best option for patients with synovitis unresponsive to a three-month trial of hematological prophylaxis. If the bleeding is refractory to three successive episodes of RS at six monthly intervals, arthroscopic synovectomy is indicated. Open synovectomy should be reserved for adults with elbow synovitis requiring radial head removal and synovectomy in the same surgical session. RS is effective and safe, and particularly helpful in patients with inhibitors as they are at greatest risk of bleeding episodes and have the highest risk of complications of surgery.

Journal article

Kumar V, Pandit HG, Liddle AD, Borror W, Jenkins C, Mellon SJ, Hamilton TW, Athanasou N, Dodd CAF, Murray DWet al., 2017, Comparison of outcomes after UKA in patients with and without chondrocalcinosis: a matched cohort study, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, Vol: 25, Pages: 319-324, ISSN: 0942-2056

Journal article

Murray DW, Liddle AD, Judge A, Pandit Het al., 2017, Bias and unicompartmental knee arthroplasty, Bone and Joint Journal, Vol: 99-B, Pages: 12-15, ISSN: 2049-4394

We recently published a paper comparing the incidence of adverse outcomes after unicompartmental and total knee arthroplasty (UKA and TKA). The conclusion of this study, which was in favour of UKA, was dismissed as “biased” in a review in Bone & Joint 360.Although this study is one of the least biased comparisons of UKA and TKA, this episode highlights the biases that exist both for and against UKA. In this review, we explore the different types of bias, particularly selection, reporting and measurement. We conclude that comparisons between UKA and TKA are open to bias. These biases can be so marked, particularly in comparisons based just on national registry data, that the conclusions can be misleading. For a fair comparison, data from randomised studies or well-matched, prospective observational cohort studies, which include registry data, are required, and multiple outcome measures should be used. The data of this type that already exist suggest that if UKA is used appropriately, compared with TKA, its advantages outweigh its disadvantages.

Journal article

Liddle AD, 2016, Patellar resurfacing after endoprosthetic replacement for primary or secondary bone tumors, Annals of Translational Medicine, Vol: 4, ISSN: 2305-5839

Journal article

Pandit H, Spiegelberg B, Clavé A, McGrath C, Liddle AD, Murray DWet al., 2016, Aetiology of lateral progression of arthritis following Oxford medial unicompartmental knee replacement: a case-control study, Musculoskeletal Surgery, Vol: 100, Pages: 97-102, ISSN: 2035-5106

PURPOSE: The aim of this case-control study is to assess for predictive factors that may determine development of lateral compartment progression after Oxford medial unicompartmental knee replacement. METHODS: Twenty-eight patients who were revised as a result of lateral osteoarthritis progression were matched to 52 alive and unrevised patients. Body mass index, intra-operative findings, postoperative leg alignment, meniscal bearing size and histological findings have been analysed. Radiological analysis was carried out on the immediate postoperative radiographs by two blinded observers to assess the severity of arthritis in the lateral compartment. The measurements of the components positions were converted into binary figures as to whether they were inside or outside the recommended limits for analysis. Conditional logistic regression was used to identify important predictors of progression, taking into account the case-control grouping. RESULTS: The results shows that the condition of the lateral compartment is a significant predictor for developing subsequent lateral compartment arthrosis (OR 2.627, p = 0.019). The study showed no relationship between progression of arthritis and component position (OR [0.5-1.18], p [0.21-1]). Nor have it demonstrated that BMI (OR 1.06, p = 0.61), postoperative leg alignment (OR 1.26, p = 0.636), meniscal bearing size (1.32, p = 0.307) or presence of chondrocalcinosis (OR 0.35, p = 0.36) have any association with lateral osteoarthritis progression. CONCLUSIONS: This study showed the importance of excluding radiographic evidence of lateral compartment osteoarthritis on the preoperative radiograph prior to medial unicompartmental knee replacement. We have not been able to show any relationship between progression of arthritis and component position. Level of proof Case-control study, level III.

Journal article

Ali AM, Pandit H, Liddle AD, Jenkins C, Mellon S, Dodd CAF, Murray DWet al., 2016, Does activity affect the outcome of the Oxford unicompartmental knee replacement?, KNEE, Vol: 23, Pages: 327-330, ISSN: 0968-0160

Journal article

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