Liam Z. Yapp

Dr. Liam Z. Yapp

orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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7 September 2022 in Bone & Joint Research
Verified
Journal Article
Open access
LYLiam Z. Yapp
Liam Z. Yapp
CSChloe E. H. Scott
Chloe E. H. Scott
CHColin R. Howie
Colin R. Howie
DMDeborah Jane Macdonald
Deborah Jane Macdonald
ASA. Hamish R. W. Simpson
A. Hamish R. W. Simpson
Nicholas David ClementNicholas David Clement
Nicholas David Clement
Aims: The aim of this study was to report the meaningful values of the EuroQol five-dimension three-level questionnaire (EQ-5D-3L) and EuroQol visual analogue scale (EQ-VAS) in patients undergoing primary knee arthroplasty (KA). Methods: This is a retrospective study of patients undergoing primary KA for osteoarthritis in a university teaching hospital (Royal Infirmary of Edinburgh) (1 January 2013 to 31 December 2019). Pre- and postoperative (one-year) data were prospectively collected for 3,181 patients (median age 69.9 years (interquartile range (IQR) 64.2 to 76.1); females, n = 1,745 (54.9%); median BMI 30.1 kg/m2 (IQR 26.6 to 34.2)). The reliability of the EQ-5D-3L was measured using Cronbach’s alpha. Responsiveness was determined by calculating the anchor-based minimal clinically important difference (MCID), the minimal important change (MIC) (cohort and individual), the patient-acceptable symptom state (PASS) predictive of satisfaction, and the minimal detectable change at 90% confidence intervals (MDC-90). Results: The EQ-5D-3L demonstrated good internal consistency with an overall Cronbach alpha of 0.75 (preoperative) and 0.88 (postoperative), respectively. The MCID for the Index score was 0.085 (95% confidence interval (CI) 0.042 to 0.127) and EQ-VAS was 6.41 (95% CI 3.497 to 9.323). The MICCOHORT was 0.289 for the EQ-5D and 5.27 for the EQ-VAS. However, the MICINDIVIDUAL for both the EQ-5D-3L Index (0.105) and EQ-VAS (-1) demonstrated poor-to-acceptable reliability. The MDC-90 was 0.023 for the EQ-5D-3L Index and 1.0 for the EQ-VAS. The PASS for the postoperative EQ-5D-3L Index and EQ-VAS scores predictive of patient satisfaction were 0.708 and 77.0, respectively. Conclusion: The meaningful values of the EQ-5D-3L Index and EQ-VAS scores can be used to measure clinically relevant changes in health-related quality of life in patients undergoing primary KA. Cite this article: Bone Joint Res 2022;11(9):619–628.

4 August 2014 in British Journal of Surgery
Verified
Journal Article
Closed access
PDF file
SCSTARSurg Collaborative
STARSurg Collaborative
SCS J Chapman
S J Chapman
JGJ Glasbey
J Glasbey
MKM Kelly
M Kelly
CKC Khatri
C Khatri
YTY H Tan
Y H Tan

4 September 2019 in Journal of Bone and Joint Surgery
Verified
Journal Article
Open access
CSChloe E. H. Scott
Chloe E. H. Scott
Nicholas David ClementNicholas David Clement
Nicholas David Clement
LYLiam Z. Yapp
Liam Z. Yapp
DMDeborah Jane Macdonald
Deborah Jane Macdonald
JPJames T. Patton
James T. Patton
RBRichard Burnett
Richard Burnett
Background: Anterior knee pain is the most common complication of total knee arthroplasty (TKA). The purpose of this study was to assess whether sagittal femoral component position is an independent predictor of anterior knee pain after cruciate-retaining single-radius TKA without routine patellar resurfacing. Methods: A prospective cohort study of 297 cruciate-retaining single-radius TKAs performed in 2006 and 2007 without routine patellar resurfacing identified 73 patients (25%) with anterior knee pain and 89 (30%) with no pain (controls) at 10 years. Patients were assessed preoperatively and at 1, 5, and 10 years postoperatively using patient-reported outcome measures (PROMs), including the Short Form-12 (SF-12), Oxford Knee Score (OKS), and satisfaction and expectation questionnaires. Variables that were assessed as predictors of anterior knee pain included demographic data, the indication for the TKA, early complications, stiffness requiring manipulation under anesthesia, and radiographic criteria (implant alignment, Insall-Salvati ratio, posterior condylar offset ratio, and anterior femoral offset ratio). Results: The 73 patients with anterior knee pain (mean age, 67.0 years [range, 38 to 82 years]; 48 [66%] female) had a mean visual analog scale (VAS) score of 34.3 (range, 5 to 100) compared with 0 for the 89 patients with no pain (mean age, 66.5 years [range, 41 to 82 years]; 60 [67%] female). The patients with anterior knee pain had mean femoral component flexion of −0.6° (95% confidence interval [CI] = −1.5° to 0.3°), which differed significantly from the value for the patients with no pain (1.42° [95% CI = 0.9° to 2.0°]; p < 0.001). The patients with and those without anterior knee pain also differed significantly with regard to the mean anterior femoral offset ratio (17.2% [95% CI = 15.6% to 18.8%] compared with 13.3% [95% CI = 11.1% to 15.5%]; p = 0.005) and the mean medial proximal tibial angle (89.7° [95% CI = 89.2° to 90.1°] compared with 88.9° [95% CI = 88.4° to 89.3°]; p = 0.009). All PROMs were worse in the anterior knee pain group at 10 years (p < 0.05), and the OKSs were worse at 1, 5, and 10 years (p < 0.05). Multivariate analysis confirmed femoral component flexion, the medial proximal tibial angle, and an Insall-Salvati ratio of <0.8 (patella baja) as independent predictors of anterior knee pain (R2 = 0.263). Femoral component extension of ≥0.5° predicted anterior knee pain with 87% sensitivity. Conclusions: In our study, 25% of patients had anterior knee pain at 10 years following a single-radius cruciate-retaining TKA without routine patellar resurfacing. Sagittal plane positioning and alignment of the femoral component were associated with long-term anterior knee pain, with femoral component extension being a major risk factor. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

31 December 2019 in Journal of Bone and Joint Surgery
Verified
Journal Article
Closed access
LYLiam Z. Yapp
Liam Z. Yapp
JNJamie A. Nicholson
Jamie A. Nicholson
CRC. Michael Robinson
C. Michael Robinson
Background: The aim of this study was to evaluate the long-term efficacy of arthroscopic Bankart repair (ABR). Methods: Eighty-eight patients with an age of ≤35 years who had sustained a primary anterior glenohumeral dislocation were enrolled in a single-center, double-blinded clinical trial. Subjects were randomized to receive either an arthroscopic washout (AWO) or ABR. Participants were reassessed after a minimum of 10 years postoperatively. Data regarding recurrent instability, revision surgery, satisfaction, and function (Disabilities of the Arm, Shoulder and Hand [DASH] and Western Ontario Shoulder Instability Index [WOSI]) scores were collected. Results: Sixty-five patients (74%; 32 in the AWO group and 33 in the ABR group) were included and had an average follow-up of 14.2 years (range,12 to 16 years). The rate of recurrent dislocation was significantly higher in the AWO group than the ABR group (47% and 12%, respectively; p = 0.002). Kaplan-Meier curves were plotted for event-free survival using recurrent instability and/or revision surgery as clinical end points. This analysis demonstrated a sustained significant difference between the groups at 10 years after surgery (58% for the AWO group versus 79% for the ABR group; log-rank test [Mantel-Cox]; p = 0.018). Long-term WOSI scores were significantly better in the ABR group. The presence of recurrent instability was associated with significantly poorer WOSI and DASH scores. Conclusions: This study demonstrates a long-term benefit in overall shoulder stability and functional outcome in high-risk patients who have undergone ABR for first-time anterior dislocation. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

1 March 2021 in Bone & Joint Open
Verified
Journal Article
Open access
LYLiam Z. Yapp
Liam Z. Yapp
JCJon V. Clarke
Jon V. Clarke
MMMatthew Moran
Matthew Moran
ASA Hamish R W. Simpson
A Hamish R W. Simpson
CSChloe E H. Scott
Chloe E H. Scott
Aims: The COVID-19 pandemic led to a national suspension of “non-urgent” elective hip and knee arthroplasty. The study aims to measure the effect of the COVID-19 pandemic on total hip arthroplasty (THA) and total knee arthroplasty (TKA) volume in Scotland. Secondary objectives are to measure the success of restarting elective services and model the time required to bridge the gap left by the first period of suspension. Methods: A retrospective observational study using the Scottish Arthroplasty Project dataset. All patients undergoing elective THAs and TKAs during the period 1 January 2008 to 31 December 2020 were included. A negative binomial regression model using historical case-volume and mid-year population estimates was built to project the future case-volume of THA and TKA in Scotland. The median monthly case volume was calculated for the period 2008 to 2019 (baseline) and compared to the actual monthly case volume for 2020. The time taken to eliminate the deficit was calculated based upon the projected monthly workload and with a potential workload between 100% to 120% of baseline. Results: Compared to the period 2008 to 2019, primary TKA and THA volume fell by 61.1% and 53.6%, respectively. Since restarting elective services, Scottish hospitals have achieved approximately 40% to 50% of baseline monthly activity. With no changes in current workload, by 2021 there would be a reduction of 9,180 and 10,170 for THA and TKA, respectively. Conversely, working at 120% baseline monthly output, it would take over four years to eliminate the deficit for both TKA and THA. Conclusion: This national study demonstrates the significant impact that COVID-19 pandemic has had on overall THA and TKA volume. In the six months after resuming elective services, Scottish hospitals averaged less than 50% normal monthly output. Loss of operating capacity will increase treatment delays and likely worsen overall morbidity. Cite this article: Bone Joint Open 2021;2(3):203–210.

1 April 2021 in The Bone & Joint Journal
Verified
Journal Article
Closed access
LYLiam Z. Yapp
Liam Z. Yapp
PWPhil J. Walmsley
Phil J. Walmsley
MMMatthew Moran
Matthew Moran
JCJon V. Clarke
Jon V. Clarke
ASA. Hamish R. W. Simpson
A. Hamish R. W. Simpson
CSChloe E. H. Scott
Chloe E. H. Scott
Aims: The aim of this study was to measure the effect of hospital case volume on the survival of revision total knee arthroplasty (RTKA). Methods: This is a retrospective analysis of Scottish Arthroplasty Project data, a nationwide audit which prospectively collects data on all arthroplasty procedures performed in Scotland. The primary outcome was RTKA survival at ten years. The primary explanatory variable was the effect of hospital case volume per year on RTKA survival. Kaplan-Meier survival curves were plotted with 95% confidence intervals (CIs) to determine the lifespan of RTKA. Multivariate Cox proportional hazards were used to estimate relative revision risks over time. Hazard ratios (HRs) were reported with 95% CI, and p-value < 0.05 was considered statistically significant. Results: From 1998 to 2019, 8,301 patients (8,894 knees) underwent RTKA surgery in Scotland (median age at RTKA 70 years (interquartile range (IQR) 63 to 76); median follow-up 6.2 years (IQR 3.0 to 10.2). In all, 4,764 (53.6%) were female, and 781 (8.8%) were treated for infection. Of these 8,894 knees, 957 (10.8%) underwent a second revision procedure. Male sex, younger age at index revision, and positive infection status were associated with need for re-revision. The ten-year survival estimate for RTKA was 87.3% (95% CI 86.5 to 88.1). Adjusting for sex, age, surgeon volume, and indication for revision, high hospital case volume was significantly associated with lower risk of re-revision (HR 0.78 (95% CI 0.64 to 0.94, p < 0.001)). The risk of re-revision steadily declined in centres performing > 20 cases per year; risk reduction was 16% with > 20 cases; 22% with > 30 cases; and 28% with > 40 cases. The lowest level of risk was associated with the highest volume centres. Conclusion: The majority of RTKA in Scotland survive up to ten years. Increasing yearly hospital case volume above 20 cases is independently associated with a significant risk reduction of re-revision. Development of high-volume tertiary centres may lead to an improvement in the overall survival of RTKA. Cite this article: Bone Joint J 2021;103-B(4):602–609.