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Introduction: Total knee arthroplasty (TKA) is an efficacious operation that improves pain and function in patients with knee arthritis. Because of the population ageing trend in Hong Kong, there is a need to determine the safety profile of TKA in older patients. This study examined the age of patients who underwent TKA in the past 10 years in Hong Kong; the aim was to investigate the mortality safety profile and clinical outcomes of TKA in patients aged ≥80 years., Methods: This study included all patients who underwent primary TKA in the Hospital Authority (HA) from 2010 to 2019. Incidences of 30-day, 90-day, and 1-year mortality were established. Clinical outcomes of patients aged ≥80 years in one cluster of HA hospitals were assessed., Results: Between 2010 and 2019, 25 040 TKA procedures were conducted in all HA hospitals; 2491 were conducted in patients aged ≥80 years. The median age at operation was higher during 2015-2019 than during 2010-2014 (70 vs 69 years; P<0.001); furthermore, an increase was observed in the proportion of patients aged ≥80 years at the time of operation. Incidences of 30-day, 90-day, and 1-year mortality were 0.156%, 0.35%, and 1.09%, respectively., Conclusions: In this first study to examine the safety profile of TKA in older patients in Hong Kong, the mean age at the time of TKA and proportion of patients aged ≥80 years have steadily risen in the past decade. Even in older patients, TKA is a reasonably safe procedure.

Introduction: Diabetes mellitus is an established modifiable risk factor for periprosthetic joint infection (PJI). Haemoglobin A1c (HbA1c) is a glycaemic marker that correlates with diabetic complications and PJI. As diabetes and prediabetes are frequently asymptomatic, and there is increasing evidence to suggest a correlation between dysglycaemia and osteoarthritis, it is reasonable to provide HbA1c screening before total knee arthroplasty (TKA). The aim of the present study was to determine the prevalence of dysglycaemia in patients who underwent TKA and investigate whether HbA1c screening and optimisation of glycaemic control before TKA affects the incidence of PJI after TKA., Methods: Patients who underwent primary TKA before and after routine HbA1c screening was introduced in our unit were reviewed. Prediabetes and diabetes were defined according to the American Diabetes Association. Patients with HbA1c ≥7.5% were referred to an endocrinologist for optimisation of glycaemic control before TKA. The incidence PJI, defined according to the Musculoskeletal Infection Society criteria, was recorded., Results: A total of 729 patients (934 knees) had HbA1c screening before TKA. Of them, 17 (2.3%) and 184 (25.2%) patients had known prediabetes and diabetes, respectively, and 265 (36.4%) and 12 (1.6%) had undiagnosed prediabetes and diabetes, respectively. The incidence of PJI was significantly lower in all patients who received HbA1c screening compared with those who did not (0.2% vs 1.02%, P=0.027)., Conclusion: Screening for HbA1c before TKA provides a cost-effective opportunity to identify undiagnosed dysglycaemia. Patients identified as having dysglycaemia receive modified treatment, significantly reducing the rate of PJI when compared with historical controls., Competing Interests: All authors have disclosed no conflicts of interest.

Objective: Falls are common after total hip arthroplasty (THA) and total knee arthroplasty (TKA). While previous studies have investigated various risk factors for falls in patients following THA and TKA, no systematic reviews have summarized these risk factors. Therefore, the current systematic review aimed to summarize evidence regarding risk factors for falls in patients after THA and/or TKA., Methods: MEDLINE, EMBASE, CINAHL, SPORTDiscus, and Physiotherapy Evidence Database (from inception to June 30, 2018) were searched. The methodological quality and quality of evidence of the included studies were assessed by two independent reviewers. Relevant data regarding participants' characteristics, study design, follow-up time points, and identified risk factors were extracted. Meta-analyses and narrative syntheses were performed., Results: Twelve studies with a total of 1,292,689 participants were included. Twenty-nine identified risk factors for post-THA/TKA falls were classified into either inpatient or post-discharge risk factors. Key risk factors for both post-THA and/or post-TKA inpatient falls that showed moderate level of evidence included: postoperative complications or comorbidities and revision THA/TKA. Likewise, risk factors for post-discharge falls after THA and/or TKA that demonstrated moderate level of evidence included: medications, psychiatric diseases, living alone, prior history of TKA, falls history and female gender. The quality of the included studies varied and sample sizes were not justified., Conclusions: This review summarized both non-modifiable and modifiable risk factors for post-THA/TKA falls. Our findings highlight the importance of developing strategies to lower the falls risk among patients following THA/TKA., (Copyright © 2019 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Knee osteoarthritis is one of the most common degenerative diseases causing disability in elderly patients. Osteoarthritis is an increasing problem for ageing populations, such as that in Hong Kong. It is important for guidelines to be kept up to date with the best evidence-based osteoarthritis management practices available. The aim of this study was to review the current literature and international guidelines on non-surgical treatments for knee osteoarthritis and compared these with the current guidelines in Hong Kong, which were proposed in 2005. Internationally, exercise programmes for non-surgical management of osteoarthritis have been proven effective, and a pilot programme in Hong Kong for comprehensive non-surgical knee osteoarthritis management has been successful. Long-term studies on the effectiveness of such exercise programmes are required, to inform future changes to guidelines on osteoarthritis management., Competing Interests: No conflicts of interest are declared by the authors.

Objective: To study the efficacy and safety of single intra-articular injection of 6-mL hylan G-F 20 in Chinese patients with symptomatic knee osteoarthritis., Design: Prospective case series., Setting: Six government hospitals in Hong Kong., Patients: Patients with primary knee osteoarthritis were recruited from six government hospitals from 1 October 2010 to 31 May 2012. All patients received 6-mL intra-articular injection of hylan G-F 20., Main Outcome Measures: Pain visual analogue scale, functional visual analogue scale, and 5-point Likert scale on change of pain and function were assessed. Adverse events were checked. Radiographs were taken pre-injection and at 3 months and 1 year., Results: A total of 110 knees of 95 patients with primary knee osteoarthritis were treated. The mean age of the patients was 62 (standard deviation, 9.8) years. All patients completed 1 year of follow-up. The mean pain visual analogue scale, functional visual analogue scale, and Likert value for pain and function showed statistically significant improvements at 6 weeks, 3 months, 6 months, and 1 year compared with the pre-injection values. No significant correlations were found between changes in visual analogue scale and age, body mass index, pre-injection radiological osteoarthritis severity, serum erythrocyte sedimentation rate, or C-reactive protein. Serial radiographs did not show any changes in the radiological severity of knee osteoarthritis. Overall, 16.4% of the patients experienced mild and self-limiting adverse events., Conclusion: Hylan G-F 20 is a safe and effective therapy to relieve pain and improve function for up to 1 year in Chinese patients with knee osteoarthritis.

We report a case of bony ankylosis of the knee secondary to severe and extensive heterotopic ossification over 9 years after primary total knee arthroplasty in a 71-year-old woman.

Objectives: This study aimed to characterize subchondral bone damages of knee osteoarthritis (OA) patients in presence of the comorbidities, i.e., hypertension and type 2 diabetes mellitus (T2DM)., Methods: A total of 43 patients with advanced stage of primary knee OA were recruited, and tibial plateau specimens were collected during surgery with informed consent. The specimens were processed for micro-CT and histological examination to assess the severity of subchondral bone damages. The presence of the comorbid disease, e.g., hypertension and T2DM, and the data on covariates, such as the age, gender and body mass index (BMI), were taken into account in a multi-variable linear regression model to explore the potential effect of the comorbidities on subchondral bone damages in knee OA after adjusting the covariates., Results: As compared to 15 subjects without the comorbidities, significant bone loss was observed at subchondral plate in 28 knee OA patients with hypertension and T2DM, in terms of the lower bone mineral density (BMD) (P = 0.034) and higher porosity (P = 0.032) on the medial portion of tibial plateau. After adjusting the age, gender and BMI, the presence of hypertension or T2DM was included in a regression model to explain in part the decreased BMD (r(2) = 0.551, P = 0.004) and increased porosity (r(2) = 0.545, P = 0.003) at subchondral plate in knee OA., Conclusion: Our findings suggest the biological link between bone loss at subchondral bone plate in knee OA and the comorbid diseases, i.e., hypertension and T2DM, which prompt the needs for a large-scale cohort study to confirm the causality., (Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: This study aimed to characterize the in-situ mechanical property and morphology of individual collagen fibril in osteoarthritic cartilage using indentation-type atomic force microscopy (IT-AFM)., Methods: The specimens with intact articular cartilage (AC), mild to severe degenerated cartilage from osteoarthritis (OA) were collected with informed consent from the postmenopausal women who underwent hip or knee arthroplasty. The fresh specimens were cryo-sectioned by layers with 50μm thick for each from the articular surface to calcified cartilage, and then processed for AFM imaging and nanoindentation test. For each layer, a total of 20 collagen fibrils were randomly selected for testing. AFM tips with the nominal radius less than 10nm were employed for probing the individual collagen fibril, and the obtained cantilever deflection signal and displacement were recorded for calculating its elastic modulus., Results: An intact AC exhibited a gradation in elastic modulus of collagen fibrils from articular surface (2.65 ± 0.31 GPa) to the cartilage-bone interface (3.70 ± 0.44 GPa). It was noted in mildly degenerated OA cartilage that the coefficient of variation for mechanical properties of collagen fibers, ranging from 25% to 48%, significantly increased as compared with intact one (12%). The stiffened collagen fibrils occurred at either articular surface (3.11 ± 0.91 GPa) or the cartilage-bone interface (5.64 ± 1.10 GPa), accompanied by loosely organized meshwork with advancement of OA cartilage degeneration. It was echoed by histological findings of OA cartilage, including fibrotic changes of surface region and tidemark irregularities., Conclusion: The stiffened collagen fibrils in AC occurred with OA onset and progression, not only at articular surface but also the cartilage-bone interface., (Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: To review the epidemiology of total knee arthroplasty for primary osteoarthritis and the change of patient characteristics over the last decade., Design: Retrospective review., Setting: A tertiary referral centre for joint replacement surgery in a teaching hospital in Hong Kong., Patients: All patients who underwent primary total knee arthroplasty for primary knee osteoarthritis from January 2000 to December 2009., Results: In all, 1157 total knee arthroplasties (589 left and 568 right) were performed on 588 females and 162 males. The annual number of total knee arthroplasties increased from 91 in 2000 to 181 in 2009. The annual number of patients increased from 58 (46 female, 12 male) in 2000 to 159 (117 female, 42 male) in 2009. When compared yearly results, there were no significant changes in the preoperative Knee Society Knee Score, Knee Society Functional Assessment, and passive range of motion of these patients. However, there was a significant decreasing trend with regard to lower limb mechanical axis mal-alignment, from 15.1° deviation from the neutral axis in 2000, to 14.8° deviation in 2004, and then 12.9° deviation in 2009 (mostly varus deformity). There was no difference between left knees and right knees, and between females and males. The mean age of the patients did not show significant change over the past decade, but the number and proportion of patients over 80 years old showed an increase from 4.8% (2000 to 2004) to 13.8% (2005 to 2009). On the other hand, the number and proportion of patients under the age of 60 years did not change., Conclusions: There was an increasing trend towards total knee arthroplasties, both in terms of number of operations and patients. The number of younger patients having total knee arthroplasty did not increase over the last 10 years, whereas the number of those older than 80 years increased significantly over that period.

Purpose: To assess inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line in a cadaveric model mimicking total knee arthroplasty., Methods: Four cadaveric knees with intact soft tissues were used. The knees were exposed anteriorly using the Insall approach, with the patella everted laterally. Three observers (2 surgeons and one trainee) took turns to identify the anatomic landmarks of the transepicondylar axis and Whiteside's line. Each observer repeated the process 20 times. Each identification was photographed and referenced with the true values obtained from the knees after they were stripped of all soft tissue. Inter- and intra-observer errors in the anatomic landmarks were compared., Results: Inter-observer error was significant with both the transepicondylar axis and Whiteside's line (p<0.001, one-way ANOVA). The intra-observer variation was greater for Whiteside's line than the transepicondylar axis (standard deviation, 4.2 vs 2.5 degrees). The maximum potential errors in the transepicondylar axis and Whiteside's line were 13 degrees and 24 degrees, respectively., Conclusion: The accuracy of rotational alignment of the transepicondylar axis and Whiteside's line were operator-dependent, and their intra-operative reproducibility was low.