Publications by authors named "Ngai-Nung Lo"

135 Publications

The patient acceptable symptom state for the knee society score, oxford knee score and short form-36 following unicompartmental knee arthroplasty.

Knee Surg Sports Traumatol Arthrosc 2021 Apr 28. Epub 2021 Apr 28.

Department of Orthopaedic Surgery, Singapore General Hospital, 20 College Road, Academia, Level 4, Singapore, 169865, Singapore.

Purpose: The patient acceptable symptom state (PASS) is a target value on a patient-reported outcome measures (PROM) scale beyond which patients deem themselves to have attained an acceptable outcome. This study aimed to define the PASS thresholds for generic and knee-specific PROMs at 2 years after unicompartmental knee arthroplasty (UKA).

Methods: Prospectively collected data of 955 patients who underwent UKA for medial osteoarthritis at a single institution was reviewed. Patients were assessed preoperatively and 2 years postoperatively using the Knee Society Knee Score (KSKS), Function Score (KSFS), Oxford Knee Score (OKS), SF-36 Physical Component Score (PCS) and Mental Component Score (MCS). Responses to an anchor question assessing patients' overall rating of treatment results were dichotomized and used to determine if PASS was achieved. PASS thresholds for each PROM were selected based on the Youden index on a receiver operating characteristics (ROC) curve. Sensitivity analyses were performed for different subgroups (by age, gender, BMI), baseline score tertiles and an alternate definition of PASS.

Results: In total, 92.7% reported their current state as acceptable. The areas under the curve (AUC) for ROCs were 0.72-0.83, except for the SF-36 PCS (AUC 0.64), indicating good discriminative accuracy of the other PROMs. PASS thresholds were 85.5 for KSKS, 77.5 for KSFS, 41.5 for OKS, 49.9 for SF-36 PCS and 54.6 for SF-36 MCS. Sensitivity analyses revealed that the thresholds were robust. Patients who attained a PASS were at least 4-5 times more likely to be satisfied and have expectations fulfilled.

Conclusion: PASS thresholds can be used to define treatment success in future outcome studies. At the individual level, they provide clinically relevant benchmarks for surgeons when assessing postoperative recovery.

Level Of Evidence: III.
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http://dx.doi.org/10.1007/s00167-021-06592-xDOI Listing
April 2021

No difference in long-term outcomes between men and women undergoing medial fixed-bearing cemented unicompartmental knee arthroplasty: A retrospective cohort study with minimum 10-year follow up.

Knee 2021 Apr 3;30:26-34. Epub 2021 Apr 3.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: Some studies have suggested that women have poorer short-term outcomes after unicompartmental knee arthroplasty (UKA) due to a higher incidence of implant overhang. This study aimed to compare patient-reported outcome measures (PROMs) between men and women after UKA at a minimum follow-up of 10 years.

Methods: Patients who underwent medial fixed-bearing UKA by two arthroplasty surgeons were identified from an institutional joint registry. Men and women were matched for age, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists class, range-of-motion and baseline PROMs using propensity scores. PROMs were compared at 2 and 10 years. Patients also completed a satisfaction questionnaire during these visits. Radiographic outliers were defined as > 2 mm of overhang.

Results: A total of 128 patients were included. There was no difference in complications, length of stay or readmissions. Women had poorer Knee Society functional scores, Short-Form 36 physical and mental component scores (SF-36 MCS) at 2 years. No difference in PROMs was found at 10 years, except for poorer SF-36 MCS in women (P = 0.041). At 10 years, 96% of women and 92% of men were satisfied (P = 0.243). Fifteen-year survivorship free from any revision was 96% in each group. There were more medial-tibial outliers in women (9%) compared with men (5%) (P = 0.018). However, no association between outliers and outcomes or survivorship was found on multivariate analyses.

Conclusion: There was nodifference in clinical outcomes between men and women undergoing UKA at a minimum follow-up of 10 years. While women had a higher incidence of medial tibial overhang, this was not associated with long-term outcomes or survivorship.
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http://dx.doi.org/10.1016/j.knee.2021.03.006DOI Listing
April 2021

Preoperative Mental Health Influences Patient-Reported Outcome Measures and Satisfaction After Revision Total Knee Arthroplasty.

J Arthroplasty 2021 Mar 12. Epub 2021 Mar 12.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: A higher prevalence of mental health conditions has been reported in patients undergoing revision total knee arthroplasty (rTKA). This study investigated the effect of preoperative mental health on patient-reported outcome measures (PROMs) and satisfaction after rTKA.

Methods: A total of 245 patients who underwent rTKA in 2004-2018 were identified from our institutional joint registry. The most common indications were aseptic loosening (n = 111), infection (n = 70), and instability (n = 35). 36-item Short-Form health survey (SF-36) mental component summary (MCS) was used to stratify the cohort into: Low-MCS (SF-36 MCS <50; n = 112) and control (SF-36 MCS ≥50; n = 133) groups. Knee Society score, Oxford knee score, SF-36 physical score, and a satisfaction questionnaire were used to compare the low-MCS and control at 6 months and 2 years.

Results: All PROMs were poorer in the low-MCS group at 6 months and 2 years. However, both groups demonstrated a comparable improvement in each PROM and a similar proportion attained the minimal clinically important difference. Fewer patients in the low-MCS group were satisfied at 2 years (72.2% vs 84.5%, P = .045). Lower preoperative SF-36 MCS was independently associated with increased odds of dissatisfaction (OR 1.037, 95% CI 1.004-1.070, P = .027). Although the change in SF-36 MCS was greater in the low-MCS group, the final value remained lower at 2 years.

Conclusion: While patients with poor mental health had inferior PROMs preoperatively and postoperatively, a similar percentage experienced a clinically meaningful improvement at 2 years. Perioperative optimization of psychological factors should still be emphasized as these patients were at a higher risk of dissatisfaction after rTKA.
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http://dx.doi.org/10.1016/j.arth.2021.03.026DOI Listing
March 2021

Early postoperative straight leg raise is associated with shorter length of stay after unilateral total knee arthroplasty.

J Orthop Surg (Hong Kong) 2021 Jan-Apr;29(1):23094990211002294

Department of Orthopaedic Surgery, 37581Singapore General Hospital, Singapore.

Purpose: Shorter length of stay (LOS) after total knee arthroplasty (TKA) is cost-effective. Straight leg raise (SLR) is a common exercise prescribed after TKA, but the significance of early postoperative SLR is unknown. The primary aim of this study is to evaluate the association between early postoperative SLR and LOS. Secondary aims are to explore associations among early postoperative SLR, time to ambulation, and time to stairs climbing and identify factors related to postoperative SLR.

Methods: 888 TKAs (888 knees, 865 patients) performed at a tertiary hospital in 2016 were included for this retrospective study. All TKAs were performed with medial parapatellar approach and tourniquet. Time to events (SLR, ambulation, stair climbing), LOS and factors influencing these events were analysed using a multivariate Poisson regression model and logistic regression.

Results: Patients who performed SLR on postoperative day 1 (POD1) had shorter LOS than those who did not (adjusted Mean Ratio (aMR) = 0.846, p < 0.001), with estimated mean LOS being 3.5 days and 4.1 days, respectively. Performing SLR on POD1 was also associated with shorter time to ambulation (aMR = 0.789; p < 0.001) and stair climbing (aMR = 0.811, p < 0.001). Female gender and higher rest pain on POD1 were associated with delayed postoperative SLR.

Conclusion: Performing SLR on POD1 after TKA is associated with shorter LOS, time to ambulation, and time to stair climbing. Early postoperative SLR can prognosticate early recovery and discharge. Optimization of preoperative muscle strength and postoperative pain may be important in early recovery after TKA.
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http://dx.doi.org/10.1177/23094990211002294DOI Listing
March 2021

Early Postoperative Pain After Total Knee Arthroplasty Is Associated With Subsequent Poorer Functional Outcomes and Lower Satisfaction.

J Arthroplasty 2021 Feb 25. Epub 2021 Feb 25.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: There are few studies investigating the effects of acute postoperative pain on functional outcomes after total knee arthroplasty (TKA). The aims of this study are to identify perioperative factors associated with increased early postoperative pain and investigate the effects of acute postoperative day 1 and 2 pain on outcomes at 6 months and 2 years post-TKA.

Methods: 1041 unilateral TKA patients were included in this retrospective cohort study. Patients were categorized into minor (visual analog scale: VAS <5) and major (VAS ≥5) pain groups based on postoperative day 1/2 VAS scores. Patients were assessed preoperatively, at 6 months and 2 years using Knee Society Knee Score and Function Scores (KSFS), Oxford Knee Score (OKS), SF-36 physical and mental component score (SF-36 PCS), expectation and satisfaction scores. Perioperative variables including age, gender, race, body mass index, American Society of Anesthesiologist status, type of anesthesia, and presence of caregiver were analyzed as predictors of postoperative acute pain. Wilcoxon two-sample test was used to analyze outcomes significantly associated with "major pain." Multiple logistic regression was used to identify predictors of "major pain."

Results: Patients with "minor pain" had significantly better KSFS, Knee Society Knee Score, OKS, and SF-36 PCS scores at 6 months and significantly better KSFS, OKS, SF-36 PCS, and satisfaction at 2 years (P < .05). A significantly higher percentage of patients with "minor pain" met the minimal clinically important difference for SF-36 PCS at 6 months and KSFS at 2 years (P < .05). Women, Indian/Malay race, higher BMI, and use of general over regional anesthesia were independent predictors of getting "major pain" (P < .05).

Conclusion: Patients should be counseled about risk factors of postoperative pain to manage preoperative expectations of surgery. Patients should be managed adequately using multimodal pain protocols to improve subsequent functional outcomes while avoiding unnecessary opioid use.
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http://dx.doi.org/10.1016/j.arth.2021.02.044DOI Listing
February 2021

Change in Body Mass Index after Simultaneous Bilateral Total Knee Arthroplasty: Risk Factors and Its Influence on Functional Outcomes.

J Arthroplasty 2021 Jan 28. Epub 2021 Jan 28.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: Previous studies evaluating weight changes following total knee arthroplasty (TKA) were performed on heterogenous cohorts. However, no study has evaluated weight changes in a cohort of simultaneous-bilateral TKA (SB-TKA) patients. This study aimed to evaluate the prevalence of patients who lost or gained weight, determine if postoperative weight change influences functional outcome, and identify predictors of weight change after SB-TKA.

Methods: Prospectively collected registry data of 560 patients who underwent SB-TKA were reviewed. Patients were assessed preoperatively, at 6 months, and 2 years using the Knee Society Score, Oxford Knee Score, Short-Form 36, and range of motion. Change in body mass index (BMI) >5% was used to categorize patients into 3 groups: lost, maintained, or gained weight. Analysis of variance, Kruskal-Wallis test, and chi-squared test were used to compare functional outcomes between groups. Multivariable logistic regression evaluated predictors for postoperative weight changes.

Results: At 2 years, 59% of patients maintained weight, 28% of patients gained weight, and 13% of patients lost weight. All groups experienced similar improvements in functional outcomes, rates of minimal clinically important difference attainment, and patient satisfaction (P > .05). Older patients were more likely to gain weight (P < .05). Patients with higher preoperative BMI were more likely to gain weight (P < .05) and less likely to lose weight (P < .05). Patients with greater preoperative comorbidities were less likely to lose weight (P < .05).

Conclusion: Up to 41% of patients experience significant weight changes after SB-TKA. Older patients with higher preoperative BMI were more likely to gain weight, while higher preoperative BMI with more comorbidities were less likely to lose weight following SB-TKA; however, postoperative weight changes do not appear to affect functional outcomes.

Level Of Evidence: III, therapeutic study.
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http://dx.doi.org/10.1016/j.arth.2021.01.059DOI Listing
January 2021

The effect of tibial and femoral component coronal alignment on clinical outcomes and survivorship in unicompartmental knee arthroplasty.

Bone Joint J 2021 Feb;103-B(2):338-346

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Aims: This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA.

Methods: Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups.

Results: Significant two-way interaction effects between TCCA and FCCA were identified. Adjusted for each other and their interaction, a TCCA of between 2° and 4° and a FCCA of between 0° and 2° were found to be associated with the greatest improvements in knee scores and the probability of fulfilling expectations and satisfaction at ten years. Patients in the optimal group whose TCCA and FCCA were between 2° and 4°, and 0° and 2°, respectively, had a significant survival benefit at 15 years compared with the non-optimal group (optimal: survival = 100% vs non-optimal: survival = 92%, 95% confidence interval (CI) 88% to 96%).

Conclusion: Significant two-way interactions between the TCCA and FCCA demonstrate the importance of evaluating the alignment of the components concomitantly in future studies. By doing so, we found that patients who concomitantly had both a TCCA of between 2° and 4° and a FCCA of between 0° and 2° had the best patient-reported outcome measures at ten years and better survivorship at 15 years. Cite this article: 2021;103-B(2):338-346.
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http://dx.doi.org/10.1302/0301-620X.103B2.BJJ-2020-0959.R1DOI Listing
February 2021

Posterior condylar offset and posterior tibial slope targets to optimize knee flexion after unicompartmental knee arthroplasty.

Knee Surg Sports Traumatol Arthrosc 2021 Jan 29. Epub 2021 Jan 29.

Department of Orthopaedic Surgery, Singapore General Hospital, 20 College Road, Academia, Level 4, Singapore, 169856, Singapore.

Purpose: To evaluate the relationship between posterior tibial slope (PTS), posterior condylar offset (PCO), femoral sagittal angle (FSA) on clinical outcomes, and propose optimal sagittal plane alignments for unicompartmental knee arthroplasty (UKA).

Methods: Prospectively collected data of 265 medial UKA was analysed. PTS, PCO, FSA were measured on preoperative and postoperative lateral radiographs. Clinical assessment was done at 6-month, 2-year and 10-year using Oxford Knee Score, Knee Society Knee and Function scores, Short Form-36, range of motion (ROM), fulfilment of satisfaction and expectations. Implant survivorship was noted at mean 15-year. Kendall rank correlation test evaluated correlations of sagittal parameters against clinical outcomes. Multivariable linear regression evaluated predictors of postoperative ROM. Effect plots and interaction plots were used to identify angles with the best outcomes. (p < 0.05) was the threshold for statistical significance.

Results: There were significant correlations between PTS, PCO and FSA. Younger age, lower BMI, implant type, greater preoperative flexion, steeper PTS and preservation of PCO were significant predictors of greater postoperative flexion. There were significant interaction effects between PTS and PCO. Effect plots demonstrate a PTS between 2° to 8° and restoration of PCO within 1.5 mm of native values are optimal for better postoperative flexion. Interaction plot reveals that it is preferable to reduce PCO by 1.0 mm when PTS is 2° and restore PCO at 0 mm when PTS is 8°.

Conclusion: UKA surgeons and future studies should be mindful of the relationship between PTS, PCO and FSA, and avoid considering them in isolation. When deciding on the method of balancing component gaps in UKA, surgeons should rely on the PTS. Decrease the posterior condylar cut when PTS is steep, and increase the posterior condylar cut when PTS is shallow. The acceptable range for PTS is between 2° to 8° and PCO should be restored to 1.5 mm of native values.

Level Of Evidence: II.
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http://dx.doi.org/10.1007/s00167-021-06453-7DOI Listing
January 2021

Mid-term functional outcomes of patient-specific versus conventional instrumentation total knee arthroplasty: a prospective study.

Arch Orthop Trauma Surg 2021 Apr 2;141(4):669-674. Epub 2021 Jan 2.

Department of Orthopaedic Surgery, Singapore General Hospital, Block 6 Level 7, Outram Road, Singapore, 169608, Singapore.

Introduction: Patient-specific instrumentation (PSI) utilizes three-dimensional imaging to produce total knee arthroplasty cutting jigs which matches patient's native anatomy. However, there are limited mid- to long-term studies examining its clinical efficacy. The aim of this study was to compare functional outcomes of PSI surgery versus conventional TKA surgery at 5-year follow-up.

Materials And Methods: Sixty patients were prospectively recruited into either the MRI-based PSI or conventional TKA group. Functional outcomes were assessed using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS), while quality of life was evaluated with the Physical Component Score (PCS) and Mental Component Score (MCS) of Short-Form 36 and compared between the two groups at 5-year follow-up.

Results: Although the PCS was 7 ± 3 points better in the PSI group preoperatively (p = 0.017), it became 5 ± 2 points worse than the conventional group at 5-year follow-up (p = 0.025). As compared to the PSI group, the conventional group showed a significantly greater improvement in PCS at 5 years as compared to before surgery (p = 0.003). There were no significant differences in KSFS, KSKS, OKS or MCS between the two groups.

Conclusions: PSI TKA did not result in improved functional outcomes or better quality of life when compared to conventional TKA. The additional costs and waiting time associated with PSI are not justifiable and therefore not recommended as an alternative to conventional TKA.

Level Of Evidence: II.
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http://dx.doi.org/10.1007/s00402-020-03729-4DOI Listing
April 2021

Patients With Parkinson's Disease Have Poorer Function and More Flexion Contractures After Total Knee Arthroplasty.

J Arthroplasty 2020 Nov 14. Epub 2020 Nov 14.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: Parkinson's disease (PD) may negatively influence the rehabilitative course after total knee arthroplasty (TKA). However, functional outcomes in this select group remain poorly defined. We compared complication, mortality and revision rates, as well as patient-reported outcomes, and satisfaction between patients with PD and controls after TKA.

Methods: Patients with PD who underwent primary unilateral TKA were identified and matched 1:1 with a control group using propensity scores adjusting for age, sex, body mass index, Charlson Comorbidity Index, baseline range of motion, Knee Society Knee Score, Knee Society Function Score, Oxford Knee Score, and 36-item Short-Form Health Survey Mental and Physical Component Summary. Functional outcomes and patient satisfaction were assessed at 6 months and 2 years. Complications, survivorship, and all-cause mortality were analyzed.

Results: In total, 114 patients were included. Majority of PD patients had Hoehn and Yahr stage 1 or 2 disease. Overall complication rate was 26.3% in the PD group and 10.5% in the control group (P = .030). There was no difference in transfusions, length of stay, and discharge to rehabilitation or readmissions. Patients with PD had more flexion contractures, poorer Knee Society Function Score and Oxford Knee Score at 2 years, and poorer 36-item Short-Form Health Survey Physical Component Summary at 6 months. 80.4% of patients with PD were satisfied compared with 85.5% of controls (P = .476). At follow-up of 8.5 ± 2.7 years, one TKA was revised in each group. All-cause mortality was higher in the PD group (15.8% vs 5.3%, P = .067).

Conclusion: Although patients with PD had relatively poorer knee function and quality of life, these patients still experienced significant functional gains compared with their preoperative status, and high satisfaction was achieved.

Level Of Evidence: III.
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http://dx.doi.org/10.1016/j.arth.2020.11.016DOI Listing
November 2020

Long-Term Functional Outcomes and Quality of Life at Minimum 10-Year Follow-Up After Fixed-Bearing Unicompartmental Knee Arthroplasty and Total Knee Arthroplasty for Isolated Medial Compartment Osteoarthritis.

J Arthroplasty 2021 04 1;36(4):1269-1276. Epub 2020 Nov 1.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore Level 4, Academia, Singapore 169856, Singapore.

Background: The aim of this study is to compare the long-term functional outcome and quality of life between total knee arthroplasty (TKA) and fixed-bearing unicompartmental knee arthroplasty (UKA) for the treatment of isolated medial compartment osteoarthritis.

Methods: Between 2000 and 2008, a total of 218 patients underwent primary UKA at our tertiary hospital. A TKA group was matched through 1:1 propensity score matching and adjusted for age, gender, body mass index, preoperative knee flexion, and function scores. All patients had medial compartment osteoarthritis. The patients were assessed with the range of motion, Knee Society Knee Score and Knee Society Function Score, Oxford Knee Score, Short Form-36 physical component score (PCS) and mental component score preoperatively, at 6 months, 2 years, and 10 years. Patients' satisfaction, expectation fulfillment, and minimal clinically important difference were analyzed.

Results: There were no differences in baseline characteristics between groups after propensity score matching (P > .05). UKA had greater knee flexion at all time points. Although the Knee Society Function Score was superior in UKA by 5.5, 3, and 4.3 points at 6 months, 2 years, and 10 years, respectively (P < .001), these differences did not exceed the minimal clinically important difference (Knee Society Knee Score 6.1). There were no significant differences in the Oxford Knee Score and Short Form-36 physical component score/mental component score. At 10 years, similar proportions of UKA and TKA were satisfied (90.8% vs 89.9%, P = .44) and had expectation fulfillment (89.4% vs 88.5%, P = .46). Between 2 and 10 years, all function scores deteriorated significantly for both groups (P < .01).

Conclusion: UKA and TKA are excellent treatment modalities for isolated medial compartment osteoarthritis, with similar functional outcomes, quality of life, and satisfaction at 10 years.
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http://dx.doi.org/10.1016/j.arth.2020.10.049DOI Listing
April 2021

Does obesity lead to lower rates of clinically meaningful improvement or satisfaction after total hip arthroplasty? A propensity score-matched study.

Hip Int 2020 Nov 23:1120700020974656. Epub 2020 Nov 23.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: Current literature lacks consensus regarding the impact of obesity on clinical outcomes of total hip arthroplasty (THA). The variability of results may reflect the lack of minimal clinically important difference (MCID) analysis, which helps to standardise the interpretation of patient-reported outcome measures (PROMs). We compared the PROMs, patient satisfaction and survivorship between obese and non-obese patients after THA.

Methods: Prospectively collected registry data of 192 obese patients and 192 propensity score-matched controls who underwent primary THA at a single institution were reviewed. Clinical outcomes and satisfaction rates were assessed at 6 months and 2 years. Reoperations for surgical complications and revision rates were analysed.

Results: Obese patients had a significantly poorer Oxford Hip Score (OHS) at 6 months and WOMAC-Function at 2 years. However, there was no difference in overall WOMAC, WOMAC-Pain, WOMAC-stiffness, SF-36 mental and physical component summary (PCS). A similar proportion of patients in each group achieved the MCID for OHS, WOMAC and SF-36 PCS. At 2 years, 90.3% of obese patients and 91.7% of controls were satisfied ( = 0.755). At a mean follow-up of 9 years, there were 5 reoperations (2.6%) for surgical complications in the obese group and 1 (0.5%) in the control group; whereas 12 revisions (6.3%) were recorded in the obese group and 3 (1.6%) in the control group ( = 0.021).

Conclusions: Despite a higher revision rate, obese patients undergoing THA may experience a similar level of clinical meaningful improvement and satisfaction as their non-obese counterparts. This study provides valuable prognostic information for obese patients and guides preoperative counselling.
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http://dx.doi.org/10.1177/1120700020974656DOI Listing
November 2020

Early post-operative oxford knee score and knee society score predict patient satisfaction 2 years after total knee arthroplasty.

Arch Orthop Trauma Surg 2021 Jan 12;141(1):129-137. Epub 2020 Oct 12.

Department of Orthopaedic Surgery, Singapore General Hospital, 20 College Road, Academia, Level 4, Singapore, 169865, Singapore.

Background: There is poor correlation between functional outcomes and patient satisfaction following total knee arthroplasty (TKA). We asked if early post-operative scores at 6 months or the pre- to post-operative change in scores are predictive of patient satisfaction 2 years after TKA.

Methods: We conducted a retrospective review of prospectively collected registry data of 4359 TKAs performed at a single institution. At 6 months and 2 years, the Knee Society Score (KSS), Oxford Knee Score (OKS), and Short-Form 36 scores were assessed. A satisfaction questionnaire was also completed. Logistic regression was used to generate receiver-operating characteristic (ROC) curves to assess the ability of each scoring system in predicting satisfaction at 2 years.

Results: At 2 years, 91.1% of patients were satisfied. For the absolute post-operative OKS at 6 months, an AUC of 0.762 (95% CI 0.736-0.788) and a threshold of ≤ 21.5 points (or ≥ 38.5 points on the new scale) were obtained. For the KSS knee score, an AUC of 0.704 (95% CI 0.674-0.734) and a threshold of ≥ 80.5 points were identified. The OKS performed significantly better than the KSS knee score (p = 0.03) and the other post-operative scores (p < 0.001). When analysing the change in scores pre-operatively to 6 months, the AUC was < 0.7 for all scales.

Conclusions: Early post-operative scores, specifically the OKS and KSS knee score, can predict patient satisfaction at 2 years after TKA with good accuracy. The threshold values offer surgeons an additional tool to identify patients at risk of dissatisfaction at 2 years, enabling them to intervene earlier to ensure good patient satisfaction.

Level Of Evidence: III, retrospective cohort study.
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http://dx.doi.org/10.1007/s00402-020-03612-2DOI Listing
January 2021

Unicompartmental knee arthroplasty in patients with Parkinson's disease.

Knee 2020 Oct 27;27(5):1325-1331. Epub 2020 Jul 27.

Department of Orthopedic Surgery, Singapore General Hospital, Singapore.

Background: Parkinson's disease (PD) adversely affects physical function after joint replacement. The biomechanical advantages of unicompartmental knee arthroplasty (UKA) may be particularly beneficial for these patients who suffer from gait and kinetic abnormalities. We aimed to describe the functional outcomes, complications and survivorship after UKA in patients with PD.

Methods: Ten patients (11 knees) undergoing primary fixed-bearing UKA for medial osteoarthritis were studied. Knee Society Knee (KSKS) and Function Scores (KSFS), as well as the Short-Form-36 (SF-36) Mental (MCS) and Physical Component Scores (PCS) were assessed preoperatively, at six months and at two years postoperatively. Complications, survivorship and all-cause mortality were analyzed.

Results: No perioperative complications occurred. Length of stay was 5 ± 2 days and no patients were discharged to rehabilitation or readmitted. Nine of 11 knees had a flexion contracture preoperatively and this remained unchanged at two years. KSKS and SF-36 PCS improved significantly. However, there was no improvement in KSFS or SF-36 MCS. All patients achieved minimal clinically important difference for KSKS, six of 11 for KSFS and nine of 11 for SF-36 PCS. At mean 10 ± 5 years, there was one revision for progression of osteoarthritis. Seven of 10 patients progressed in Hoehn and Yahr stage and only three were able to ambulate independently at last follow-up.

Conclusions: Patients suffering from osteoarthritis and PD can experience a substantial improvement in knee pain with low morbidity after UKA. However, the improved kinematics of UKA did not translate to an improved range of motion or knee function postoperatively.
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http://dx.doi.org/10.1016/j.knee.2020.06.017DOI Listing
October 2020

Coronal Alignment of Fixed-Bearing Unicompartmental Knee Arthroplasty Femoral Component May Affect Long-Term Clinical Outcomes.

J Arthroplasty 2021 02 1;36(2):478-487. Epub 2020 Aug 1.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Background: This study aims to investigate the clinical effects of femoral component coronal alignment in a cohort of fixed-bearing unicompartmental knee arthroplasty with clinical and radiological follow-up of 10 years.

Methods: Prospectively collected registry data of 264 consecutive, cemented, primary fixed-bearing medial unicompartmental knee arthroplasties performed at a single institution from 2004 to 2007 were reviewed. Femoral component coronal angle (FCCA), tibial component coronal angle, and hip-knee-ankle angle were measured on postoperative radiographs. Patients were grouped into acceptable (AG ≤ 3°) and outlier (OG > 3°) groups according to absolute FCCA. Clinical assessment at 6-month, 2-year, and 10-year follow-up was performed using Knee Society Knee and Function Scores, Oxford Knee Score (OKS), and Short Form-36. Fulfillment of expectations, satisfaction, and implant survivorship was recorded.

Results: There was no significant difference in demographics, tibial component coronal angle, hip-knee-ankle angle, and sagittal parameters in both groups. The OG had poorer OKS at 10 years and a larger deterioration from 2 to 10 years compared to AG (P = .02). Increase in FCCA was associated with deterioration in 2-year OKS (adjusted ß = 0.23, P = .01), 10-year OKS (adjusted ß = 0.26, P = .03), and 2-year Short Form-36 physical component score (adjusted ß = -0.44, P = .01). Expectation fulfillment at 2 years was lower in the OG vs the AG (88% vs 100%, P = .03). Both groups had similar 10-year survivorship (99% vs 98%, P = .65).

Conclusions: FCCA may affect long-term clinical outcomes, but not short-term clinical outcomes nor 10-year survivorship. Given similar limb alignment, coronal and sagittal component positioning, a larger FCCA was associated with poorer outcomes at 10-year follow-up.
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http://dx.doi.org/10.1016/j.arth.2020.07.070DOI Listing
February 2021

No difference in functional outcomes, quality of life and survivorship between metal-backed and all-polyethylene tibial components in unicompartmental knee arthroplasty: a 10-year follow-up study.

Knee Surg Sports Traumatol Arthrosc 2020 Aug 20. Epub 2020 Aug 20.

Department of Orthopaedic Surgery, Singapore General Hospital, 20 College Road, Academia, Level 4, Singapore, 169865, Singapore.

Purpose: The purpose of this study was to compare functional outcomes, quality of life and survivorship at a minimum of 10 years postoperatively, between MB and AP tibial components in fixed-bearing UKAs.

Methods: A retrospective cohort study of 146 Query ID="Q3" Text="Author names: Please confirm if the author names are presented accurately and in the correct sequence (Lo Ngai Nung, Yeo Seng Jin). Also, kindly confirm the details in the metadata are correct." UKAs performed between 2004 and 2007 by a single fellowship-trained arthroplasty surgeon was carried out. 27 UKAs received MB tibial components and 119 UKAs received AP tibial components. The cohort was followed up prospectively for 10 years. Functional outcomes were compared using the Knee Society Functional Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS). Quality of life measures were obtained from the Physical Component Summary (PCS) and Mental Component Summary (MCS), derived from the Short Form 36 Health Survey (SF-36). Propensity score matching was performed in a 1:3 ratio of MB versus AP tibial components to account for possible confounding variables. Thereafter, outcomes between the two groups were compared. The proportion of patients who had attained the minimum clinically important difference (MCID) for the abovementioned scores was recorded as well.

Results: After propensity score matching, there were 28 UKAs with MB tibial components and 76 UKAs with AP tibial components. There was no significant difference between the two groups in functional outcomes (KSFS, KSKS and OKS), quality of life (PCS and MCS) and survivorship (92.3% vs 91.1%, respectively) at a minimum of 10 years postoperatively. However, a significantly higher proportion of patients in the group with AP tibial components attained the MCID for PCS at 10 years postoperatively, compared to those with MB tibial components (p = 0.031).

Conclusion: In conclusion, there were no significant differences in functional outcomes measures, quality of life and survivorship between MP and AP tibial components at a minimum of 10 years postoperatively.

Level Of Evidence: III.
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http://dx.doi.org/10.1007/s00167-020-06247-3DOI Listing
August 2020

The effect of the comorbidity burden on vitamin D levels in geriatric hip fracture.

BMC Musculoskelet Disord 2020 Aug 8;21(1):524. Epub 2020 Aug 8.

Department of Orthopedic Surgery, Singapore General Hospital, Singapore, Singapore.

Background: Elderly patients with hip fractures often have multiple medical comorbidities, and vitamin D deficiency is common in this population. Accumulating evidence links low vitamin D levels to various comorbidities. However, very little is known about the collective impact of comorbidities on vitamin D levels. The Charlson Comorbidity Index (CCI) is a validated comorbidity burden index. We hypothesized that a high CCI score is associated with vitamin D deficiency in elderly patients with hip fracture.

Methods: A retrospective cohort study was conducted among all hospitalized elderly patients aged > 60 years admitted for low-energy hip fracture in a single tertiary hospital from 2013 to 2015. Data regarding patient demographics, fracture type, serum 25-hydroxyvitamin D3 levels and age-adjusted CCI score were collected and analysed.

Results: Of the 796 patients included in the study, 70.6% (n = 562) of the patients were women and the mean age was 77.7 ± 8.0 years. The mean vitamin D level was 20.4 ± 7.4 ng/mL, and 91.7% ofhospitalized elderly patients with hip fracture had inadequate vitamin D level. There was no correlation between the individual serum vitamin D level with respect to age-adjusted CCI (Pearson correlation coefficient = 0.01; p = 0.87). After stratifying the CCI scores into low and high comorbidity burden groups (i.e., with scores 1-2 and ≥ 3), there was no relationship between the 2 subgroups for age-adjusted CCI and vitamin D levels (p = 0.497). Furthermore, there was also no association among age, gender, fracture type, and smoking status with the mean 25(OH)D level (p > 0.05).

Conclusion: Low vitamin D levels were highly prevalent in our hip fracture cohort. There was no relationship between the CCI score and vitamin D levels in the geriatric hip population. The comorbidity burden in geriatric patients with hip fractures did not seem to be a significant factor for vitamin D levels.
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http://dx.doi.org/10.1186/s12891-020-03554-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414725PMC
August 2020

Improvements in functional outcome and quality of life are not sustainable for patients ≥ 68 years old 10 years after total knee arthroplasty.

Knee Surg Sports Traumatol Arthrosc 2020 Aug 3. Epub 2020 Aug 3.

Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road Academia Building Level 4, Singapore, 169608, Singapore.

Purpose: The aims of this study are to evaluate whether improvements in functional outcome and quality of life are sustainable 10 years after total knee arthroplasty (TKA), and the age cut-off for clinical deterioration in outcomes METHODS: Prospectively collected registry data of 120 consecutive patients who underwent TKA at a tertiary hospital in 2006 was analysed. All patients were assessed at 6 months, 2 years and 10 years using the Knee Society Function Score, Knee Society Knee Score, Oxford Knee Score, Short-Form 36 Physical/Mental Component Scores and postoperative satisfaction. One-way ANOVA was used to compare continuous variables, while Chi-squared test to compare categorical variables. Multivariate logistic regression and receiver operating curve analysis was performed to evaluate the predictive factors associated with deterioration of scores postoperatively.

Results: Significant improvements were noted in all functional outcome and quality of life scores at 6 months after TKA. Between 6 months and 2 years, the KSFS and OKS continued to improve but the KSKS, PCS and MCS plateaued. Between 2 and 10 years, there was a deterioration in the KSFS and OKS, whilst KSKS, PCS and MCS were maintained. Increasing age was noted to be a significant risk factor for deterioration of KSFS at 10 years with age ≥ 68 as the cut-off value. 91.7% of patients with KSFS Minimally Clinically Important Difference(MCID) (≥ 7 points) continued to be satisfied after 10 years compared to 100.0% who did not experience KSFS MCID deterioration (p = 0.02).

Conclusion: Patients ≥ 68 years experience deterioration in functional outcomes and quality of life from 2 to 10 years after TKA.

Level Of Evidence: Retrospective study, Level III.
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http://dx.doi.org/10.1007/s00167-020-06200-4DOI Listing
August 2020

The long-term impact of preoperative psychological distress on functional outcomes, quality of life, and patient satisfaction after total knee arthroplasty.

Bone Joint J 2020 Jul;102-B(7):845-851

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Aims: While patients with psychological distress have poorer short-term outcomes after total knee arthroplasty (TKA), their longer-term function is unknown. We aimed to 1) assess the influence of preoperative mental health status on long-term functional outcomes, quality of life, and patient satisfaction; and 2) analyze the change in mental health after TKA, in a cohort of patients with no history of mental health disorder, with a minimum of ten years' follow-up.

Methods: Prospectively collected data of 122 patients undergoing primary unilateral TKA in 2006 were reviewed. Patients were assessed pre- and postoperatively at two and ten years using the Knee Society Knee Score (KSKS) and Function Score (KSFS); Oxford Knee Score (OKS); and the Mental (MCS) and Physical Component Summary (PCS) which were derived from the 36-Item Short-Form Health Survey questionnaire (SF-36). Patients were stratified into those with psychological distress (MCS < 50, n = 51) and those without (MCS ≥ 50, n = 71). Multiple regression was used to control for age, sex, BMI, Charlson Comorbidity Index (CCI), and baseline scores. The rate of expectation fulfilment and satisfaction was compared between patients with low and high MCS.

Results: There was no difference in the mean KSKS, KSFS, OKS, and SF-36 PCS at two years or ten years after TKA. Equal proportions of patients in each group attained the minimal clinically important difference for each score. Psychologically distressed patients had a comparable rate of satisfaction (91.8% (47/51) vs 97.1% (69/71); p = 0.193) and fulfilment of expectations (89.8% vs 97.1%; p = 0.094). The proportion of distressed patients declined from 41.8% preoperatively to 29.8% at final follow-up (p = 0.021), and their mean SF-36 MCS improved by 10.4 points (p < 0.001).

Conclusion: Patients with poor mental health undergoing TKA may experience long-term improvements in function and quality of life that are comparable to those experienced by their non-distressed counterparts. These patients also achieved a similar rate of satisfaction and expectation fulfilment. Undergoing TKA was associated with improvements in mental health in distressed patients, although this effect may be due to residual confounding. Cite this article: 2020;102-B(7):845-851.
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http://dx.doi.org/10.1302/0301-620X.102B7.BJJ-2019-1562.R2DOI Listing
July 2020

Similar postoperative outcomes after total knee arthroplasty with measured resection and gap balancing techniques using a contemporary knee system: a randomized controlled trial.

Knee Surg Sports Traumatol Arthrosc 2020 Jun 15. Epub 2020 Jun 15.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Purpose: The Attune® Knee System provides new instrumentation to achieve symmetric flexion/extension gaps in total knee arthroplasty (TKA). However, there is limited information on the optimal TKA technique using this system. The aim of this randomised controlled trial was to determine which surgical technique results in better postoperative clinical outcomes after TKA using the contemporary Attune Knee System: the measured resection or gap balancing technique.

Methods: A prospective randomized controlled trial was conducted with 100 patients undergoing TKA using measured resection (n = 50) or gap balancing (n = 50) technique. The measured femoral sizer was used in the measured resection group, while the balanced femoral sizer was used in the gap balancing group. Functional outcomes and quality of life were assessed preoperatively and at 6 months and 2 years post-surgery, using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), the Physical Component Score (PCS) and Mental Component Score (MCS) of Short-Form 36 (SF-36). Using weight-bearing coronal radiographs, the hip-knee-ankle angle (HKA), coronal femoral component angle (CFA), coronal tibial component angle (CTA) and joint line height were also evaluated for each patient.

Results: There were no significant differences in the functional scores or the proportion of patients from each group who were satisfied or had their expectations fulfilled at 6 months or 2 years post-surgery. There was also no significant difference in the number of patients who attained minimum clinically important difference (MCID) postoperatively between the groups. Postoperatively, there was no significant difference in the number of HKA outliers between the groups (p = 0.202). The postoperative CFA (p = 0.265) and CTA (p = 0.479) were similar between the groups. There was also no significant difference in the absolute change (p = 0.447) or proportion of outliers (p = 0.611) for joint line height between the groups.

Conclusion: Both measured resection and gap balancing techniques resulted in comparable functional and quality of life outcomes up to 2 years post-surgery. Both techniques appear to be equally effective in achieving excellent outcomes with the Attune Knee System.

Level Of Evidence: I.
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http://dx.doi.org/10.1007/s00167-020-06103-4DOI Listing
June 2020

Ten-Year Results of Unicompartmental Knee Arthroplasty in Patients With Psychological Distress.

J Arthroplasty 2020 10 11;35(10):2830-2836.e1. Epub 2020 May 11.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Background: Although the influence of psychological distress on the outcomes of total knee arthroplasty has been described extensively, its effect on unicompartmental knee arthroplasty (UKA) is poorly defined. Furthermore, most studies in arthroplasty literature had short follow-ups of ≤1 year. We investigated the influence of psychological distress on long-term patient-reported outcomes and analyzed the change in mental health after UKA in a cohort with minimum 10 years of follow-up.

Methods: Prospectively collected data of 269 patients undergoing UKA in 2004-2007 were reviewed. Patients were stratified into those with psychological distress (36-item Short-Form health survey [SF-36] Mental Component Summary [MCS] <50, n = 111) and those without (SF-36 MCS ≥50, n = 158). Clinical outcomes were obtained preoperatively, at 2 years, and 10 years. Multiple regression was used to control for age, gender, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists class, and baseline scores. The rate of expectation fulfillment and satisfaction was compared.

Results: Psychologically distressed patients had poorer Knee Society Knee Score, Function Score, Oxford Knee Score, and SF-36 Physical Component Summary preoperatively, at 2 years, and 10 years. However, an equal proportion in each group attained the minimal clinically important difference for each score. Distressed patients had a comparable rate of satisfaction (91% vs 95%, P = .136) but lower fulfillment of expectations (89% vs 95%, P = .048). The percentage of distressed patients declined from 41% to 35% at follow-up. The mean SF-36 MCS improved by 6.9 points.

Conclusion: Although psychologically distressed patients had relatively greater pain and poorer function preoperatively and up to 10 years after UKA, a similar proportion of them experienced a clinically meaningful improvement in patient-reported outcomes.
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http://dx.doi.org/10.1016/j.arth.2020.05.011DOI Listing
October 2020

Is constraint implant with metaphyseal sleeve a viable option for revision TKR with preoperative coronal plane instability and bone defect?

J Orthop Surg (Hong Kong) 2020 Jan-Apr;28(2):2309499020926313

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Background: Metaphyseal sleeves have been used as metaphyseal filling implants to address bone loss during revision total knee replacements (TKRs). This study aims to compare the 2-year clinical and radiological outcomes of constraint implant with bone defect and constraint implant without or minimal bone defect in revisions TKR with preoperative coronal plane instability.

Materials And Methods: Seventeen cases of constraint implants with metaphyseal sleeve matched paired with 34 cases of constrained condylar knee (CCK) prosthesis. Age, gender, body mass index and aetiology for revision surgery were recorded. Clinical outcome measures included Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), Oxford Knee Score (OKS), physical component summary (PCS) and mental component summary (MCS). Radiological outcome measures included joint line changes, hip-knee-ankle angle (HKA), coronal femoral angle (CFA) and coronal tibial angle (CTA).

Result: Patients in sleeve group showed significant improvement in KSKS, KSFS and OKS (38 ± 7, 35 ± 6 and 20 ± 2 points, respectively, < 0.001), while they were 19 ± 3 and 6 ± 2 points for PCS and MCS, respectively ( < 0.001 and = 0.021). These postoperative scores after surgery were similar between the two groups at 6 months and 2 years. The sleeve provides comparable result in joint line restoration; the postoperative HKA, CFA and CTA were all comparable between the two groups.

Conclusion: Metaphyseal sleeve with constraint implant is a viable option for revision TKR with preoperative coronal plane instability and significant bone defect. It is able to achieve similar clinical outcomes and joint line restoration compared to CCK prosthesis at 2-year follow-up.
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http://dx.doi.org/10.1177/2309499020926313DOI Listing
February 2021

Do Patients With Psychological Distress Have Poorer Patient-Reported Outcomes After Total Hip Arthroplasty?

J Arthroplasty 2020 09 29;35(9):2465-2471. Epub 2020 Apr 29.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Background: Patients with psychological distress are likely to have poorer short-term functional outcomes after total knee arthroplasty. However, the influence of psychological distress on the outcomes of total hip arthroplasty (THA) is relatively understudied. Previous studies also had short follow-ups of 1 year or less. We examined the influence of psychological distress on patient-reported outcomes and satisfaction, and analyzed the change in mental health after THA at a minimum of 2 years.

Methods: Prospectively collected data of 1384 patients undergoing primary THA in 2001-2015 were reviewed. Patients were assessed using the Oxford Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index, and 36-item Short-Form health survey Physical Component Summary and Mental Component Score (MCS). Patients were stratified into those with psychological distress (MCS < 50, n = 720) and those without (MCS ≥ 50, n = 664). Multiple regression analysis was used to control for age, gender, body mass index, and baseline scores. The rate of satisfaction and expectation fulfillment was also analyzed.

Results: Distressed patients had a poorer Physical Component Summary at 6 months. However, there was no difference in patient-reported outcomes at 2 years. A higher proportion of distressed patients attained the minimal clinically important difference for Oxford Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index, while 92.2% of distressed patients and 92.9% of nondistressed patients were satisfied at 2 years (P = .724). There was no difference in MCS after 6 months. The percentage of distressed patients also declined from 41.8% to 27.3%.

Conclusion: Patients with psychological distress achieved a comparable level of function, quality of life, and satisfaction 2 years after THA. Undergoing THA may also lead to mental health improvement in a subgroup of distressed patients.
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http://dx.doi.org/10.1016/j.arth.2020.04.077DOI Listing
September 2020

Are Oxford Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index Useful Predictors of Clinical Meaningful Improvement and Satisfaction After Total Hip Arthroplasty?

J Arthroplasty 2020 09 20;35(9):2458-2464. Epub 2020 Apr 20.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Background: Up to 15% of patients express dissatisfaction after total hip arthroplasty (THA). Preoperative patient-report outcome measures (PROMs) scores can potentially mitigate this by predicting postoperative satisfaction, identifying patients that will benefit most from surgery. The aim of this study was to (1) calculate the minimal clinically important difference (MCID) thresholds for Oxford Hip Score (OHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Short Form-36 (SF-36) mental component summary (MCS) and physical component summary (PCS) scores and (2) identify the threshold values of these PROMs that could be used to predict patient satisfaction and expectation fulfilment.

Methods: Prospectively collected registry data of 1334 primary THA patients who returned for 2-year follow-up from 1998 to 2016 were reviewed. All patients were assessed preoperatively and postoperatively at 2 years using the OHS, WOMAC, and SF-36 PCS/MCS scores. The MCID for each PROMs was calculated, and the proportion of patients that attained MCID was recorded. The relationship between satisfaction, expectation fulfilment, and MCID attainment was analyzed using Spearman rank correlation. Optimal threshold scores for each PROM that predicted MCID attainment and satisfaction/expectation fulfilment at 2 years were calculated using receiver operating curve analysis.

Results: The calculated MCID for OHS, WOMAC, SF-36 PCS, and SF-36 MCS were 5.2, 10.8, 6.7, and 6.2, respectively. A threshold value of 24.5 for the preoperative OHS was predictive of achieving WOMAC MCID at 2 years after THA (area under the curve 0.80, P < .001). 93.1% of patients were satisfied, and 95.5% had expectations fulfilled at 2 years. None of the PROMs were able to predict satisfaction.

Conclusion: OHS and WOMAC scores can be used to determine clinical meaningful improvement but are limited in their ability to predict patient satisfaction after THA.
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http://dx.doi.org/10.1016/j.arth.2020.04.034DOI Listing
September 2020

Should patients aged 75 years or older undergo medial unicompartmental knee arthroplasty? A propensity score-matched study.

Arch Orthop Trauma Surg 2020 Jul 18;140(7):949-956. Epub 2020 Apr 18.

Department of Orthopaedic Surgery, Singapore General Hospital, 20 College Road, Academia, Level 4, Singapore, 169865, Singapore.

Introduction: With increasing life expectancies worldwide, more elderly patients with isolated medial compartment osteoarthritis may become suitable UKA candidates. However, there is a paucity of literature comparing outcomes between older patients (≥ 75 years) and younger patients undergoing UKA. The aim of this study was to determine if there were differences in functional and HRQoL measures between older patients (≥ 75 years) and younger controls (< 75 years) undergoing primary UKA.

Materials And Methods: Prospectively collected registry data of 1041 patients who underwent primary, cemented, fixed-bearing medial UKA at a single institution from 2002-2013 were reviewed. Propensity scores generated using logistic regression was used to match older patients (≥ 75 years, n = 94) to controls (< 75 years, n = 188) in a 1:2 ratio. Knee Society Scores, Oxford Knee Score, Short Form-36, satisfaction/expectation scores, proportion of patients attaining OKS/SF-36 PCS MCID and survivorship were analysed.

Results: Patients ≥ 75 years had significantly lower KSFS (67.1 ± 17.9 vs 79.4 ± 18.2, p < 0.001) and SF-36 PCS (47.3 ± 10.1 vs 50.4 ± 9.1, p = 0.01) as compared to the control group. In addition, a significantly lower proportion of patients ≥ 75 years attained MCID for SF-36 PCS when compared to the controls (50.0% vs 63.8%, p = 0.04). Survival rates at mean 8.3 ± 3.0 years were 98.9% (95% CI, 96.7-100) in the older group versus 92.8% (95% CI, 86.8-98.8) in the younger group (p = 0.31).

Conclusions: Our findings highlight the need to counsel older patients regarding potentially reduced improvements in functional outcomes, despite advantages of lower revision. However, UKA in older patients continues to be a viable option for isolated medial compartment osteoarthritis LEVEL OF EVIDENCE: Level III Propensity score matched study.
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http://dx.doi.org/10.1007/s00402-020-03440-4DOI Listing
July 2020

Can Octogenarians Undergoing Total Knee Arthroplasty Experience Similar Functional Outcomes, Quality of Life, and Satisfaction Rates as Their Younger Counterparts? A Propensity Score Matched Analysis of 1188 Patients.

J Arthroplasty 2020 07 19;35(7):1833-1839. Epub 2020 Feb 19.

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.

Background: Current literature lacks consensus regarding the impact of advanced age on the clinical outcomes of total knee arthroplasty (TKA). Moreover, there is paucity of literature on the subjective benefit reported by elderly patients. We compared the functional outcomes, quality of life, and satisfaction rates between octogenarians and age-appropriate controls undergoing primary TKA with a minimum follow-up of 2 years.

Methods: Prospectively collected registry data of 594 patients aged ≥80 years (n = 594) and a propensity score matched cohort of 594 patients aged 65-74 years who underwent primary TKA at a single institution were reviewed. The range of motion, clinical outcome scores, and satisfaction rates were assessed at 6 months and 2 years. Revision rates were also recorded.

Results: Octogenarians had a significantly lower Knee Society Function Score, Oxford Knee Score, and SF-36 Physical Component Summary at 6 months and 2 years (P < .05 for each). Furthermore, a lower proportion of octogenarians achieved the minimal clinically important difference for each score (P < .05 for each). Although the rates were similar at 6 months (P = .853), octogenarians were less satisfied at 2 years compared to age-appropriate controls (89.3% vs 93.3%, P = .042), and there was a trend toward poorer expectation fulfillment (88.4% vs 92.1%, P = .062).

Conclusion: Octogenarians undergoing TKA had a relatively lower rate of satisfaction and clinically meaningful improvement compared to younger controls. Nevertheless, elderly patients still experienced a successful outcome after surgery. The clinical trajectory outlined may help clinicians provide valuable prognostic information to elderly patients and guide preoperative counseling.
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http://dx.doi.org/10.1016/j.arth.2020.02.033DOI Listing
July 2020

CT-based TruMatch® Personal Solutions for knee replacement Surgery … Does it really match?

J Orthop 2020 May-Jun;19:17-20. Epub 2019 Nov 27.

Singapore General Hospital, Department of Orthopaedic Surgery, 20 College Road, Academia, Level 4, 169856, Singapore.

Objective: Patient-specific templates promises to be able to increase alignment while decreasing operative time, increasing patient throughput, decreasing instrumentation, reducing risk of fat embolism and intraoperative bleeding, decreasing tissue loss, shortening recovery, reducing post-operative pain and decreasing incidence of infection. However, multiple studies have shown conflicting results regarding these potential benefits. This study serves to critically evaluate the potential advantages and disadvantages of using a patient-specific templating technique through a single-surgeon study.

Methods: All patients who underwent primary total knee arthroplasty (TKA) for osteoarthritis of the knee using TruMatch® Personal Solutions total knee replacement by a single surgeon were identified. An age-, gender-, side-, diagnosis- and surgeon-matched cohort who underwent conventional primary TKAs was randomly identified for comparison.

Results: The average distal medial femur (p < 0.001), distal lateral femur (p < 0.001), posteromedial femur (p < 0.001), posterolateral femur (p < 0.001), medial tibial (p < 0.001) and lateral tibial (p = 0.12) predicted cuts showed significant difference from the actual corresponding cuts. Three knees also required the need to freehand. There was no significant difference in mechanical (p = 0.96) and anatomical alignments (p = 0.26), as well as the changes in mechanical (p = 0.06) and anatomical (p = 0.39) alignments between the two groups. Duration of surgery (p = 0.26), length of inpatient stay (p = 0.06) and incidence of wound infection (p = 1.00) were similar. Additionally, patients in the TruMatch® Personal Solutions group had a greater decrease drop in hemoglobin levels (p = 0.02), with five transfusions needed while only one patient in the conventional group required transfusion (p = 0.09).

Conclusion: Our early experience and results with the CT-based TruMatch® Personal Solutions templates for TKA has not been promising. Despite promised, there were no demonstrable benefits with the technology. Moreover, the disadvantage of having increased blood loss was identified. Further studies are required to recommend the use of this technology.
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http://dx.doi.org/10.1016/j.jor.2019.11.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6994790PMC
November 2019

Effects of continuing use of aspirin on blood loss in patients who underwent unilateral total knee arthroplasty.

J Orthop Surg (Hong Kong) 2020 Jan-Apr;28(1):2309499019894390

Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.

Purpose: Concerning the ongoing debate on the effects of continuing aspirin therapy on blood loss in knee arthroplasty, we conducted a retrospective investigation to test the hypothesis that continuation of aspirin prior total knee arthroplasty (TKA) will not cause more blood loss.

Methods: From a database of patients who underwent unilateral TKA between 2011 and 2016, we identified two groups: the aspirin group (patients continued aspirin during perioperative period) and the nonaspirin group (patients had no current or recent history of aspirin usage). We extracted and compared patient demographic information, comorbidity index, baseline serum hemoglobin (Hb), and creatinine level between the two groups. We also compared our primary outcomes, including the total blood loss, transfusion requirement, and length of hospitalization between the two groups. A multivariate logistic regression for analyzing the risk factors of requiring transfusion was performed.

Results: We found that apart from preoperative serum creatinine level, there was no difference in the baseline Hb level, perioperative change in Hb, total blood loss, or length of hospitalization between the two groups. The percentage of transfusion utilization was also comparable between the two groups. Our regression analysis shows that the risk of requiring transfusion after TKA is not significantly associated with patients taking aspirin therapy before operation.

Conclusion: Patients who underwent TKA with continuation of low-dose aspirin did not result in more blood loss. Current blood loss management has provided sufficient reduction of blood loss to accommodate aspirin therapy perioperatively. We suggest that it is safe to continue aspirin prior to TKA.
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http://dx.doi.org/10.1177/2309499019894390DOI Listing
December 2020

Increased constraint of rotating hinge knee prosthesis is associated with poorer clinical outcomes as compared to constrained condylar knee prosthesis in total knee arthroplasty.

Eur J Orthop Surg Traumatol 2020 Apr 16;30(3):529-535. Epub 2019 Dec 16.

Department of Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore, 169608, Republic of Singapore.

The aim of this study was to evaluate whether there are any differences in patient-reported outcome measures between semi-constrained condylar constrained knee (CCK) and fully constrained rotating hinge knee (RHK) prostheses in midterm follow-up. We reviewed prospectively collected data of our hospital arthroplasty registry between 2007 and 2014. Thirty-nine patients were identified to have RHK prosthesis TKA and matched for a number of primary/revision TKA, gender, age, body mass index and pre-operative clinical scores to a control group of 78 patients with CCK TKA. Patient demographics, range of movement, varus/valgus deformity, Short Form 36 (SF-36) scores, Oxford Knee Score (OKS), Knee Society Score (KSS) and patient satisfaction were evaluated. Pre-operatively, the RHK and the control group of CCK had similar demographics, proportion of primary/revision TKA and baseline clinical scores (p > 0.05). At 2-year follow-up, patients with CCK prostheses had significantly better clinical outcomes as compared to patients with RHK prosthesis in terms of KSS functional scores, OKS, SF-36 sub-domains of physical functioning, physical role functioning and physical component score. We conclude that at midterm follow-up of 2 years, the CCK patients as compared to RHK patients reported better clinical and functional outcomes in terms of OKS, KSS functional score and SF-36 with a greater proportion of patients who were satisfied and had their expectations met by surgery. Further biomechanical studies are needed to investigate the association between component constraint and clinical outcomes for these prostheses.
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http://dx.doi.org/10.1007/s00590-019-02598-xDOI Listing
April 2020

Satisfaction Rates Are Low following Revision Total Knee Arthroplasty in Asians Despite Improvements in Patient-Reported Outcome Measures.

J Knee Surg 2020 Oct 4;33(10):1041-1046. Epub 2019 Jul 4.

SingHealth Duke-NUS Musculoskeletal Sciences Academic Clinical Programme, Singapore, Singapore.

With the aging population in Asia and increase in total knee arthroplasty (TKA) utilization rates, the number of patients requiring revision TKA (rTKA) are expected to increase as well. The purpose of this study was to evaluate outcomes and satisfaction rates following rTKA in an Asian population that has unique cultural demands. Registry data of patients who underwent rTKA from 2006 to 2010 and had completed 5 years of follow-up were analyzed. Flexion range, Oxford Knee score (OKS), Knee Society score (KSS), the Short-Form 36 (SF-36), and satisfaction rates were assessed for improvement from preoperative values, as well as by the minimum clinically important difference (MCID) criterion. rTKA was performed in 163 patients. There were significant improvements seen at 2 years postoperatively and these were sustained up to 5 years. The minimal clinically important difference (MCID) criterion for KSS, OKS, and SF-36 physical component score (PCS) was met at 2 and 5 years postoperatively. The overall complication rate was 3.7% at a mean follow-up of 8.4 years. A total of 121 patients (74.2%) were satisfied at 5 years postoperatively. Within our cohort, rTKA results in significantly improved patient-reported outcome measures with a low complication rate of 3.7% at a minimum of 5-year follow-up. Despite these encouraging results, satisfaction rates remain low.
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http://dx.doi.org/10.1055/s-0039-1692629DOI Listing
October 2020