Total Joint Replacement Surgery Research Articles

Study on the Surface Texture-Microparticles Synergistic Lubrication Mechanism of Artificial Joint

Abstract After total joint replacement surgery, frequent injection of lubricating substances is required due to lubrication failure caused by the absorption of lubricants by the human body, which will cause serious physiological and psychological burdens on patients. In this study, with the help of surface texture aggregation of particles, gelatin microgel particles with a diameter of about 4 μm were used as lubricating substances to achieve aggregation in the texture, thus improving the friction environment under low-concentration lubricants. The study found that the rectangular cross-sectional texture demonstrated the most effective anti-friction properties, resulting in a 26% reduction in friction coefficient compared to non-textured surfaces. Additionally, utilizing comsol for particle flow simulation, researchers observed the motion behavior of particles within the texture and clarified the mechanism of particle aggregation and the improvement of lubrication on the surface. This article confirms the beneficial effects of combining surface texture and particles on lubrication, thus providing valuable insight for improving lubrication in dilute particle solutions.

Effect of non-contact induction heating on HA coatings and bone cement, an ex vivo study

Background Prosthetic joint infection is a serious complication that can arise after total joint replacement surgery. When bacteria colonise an orthopaedic implant, they form biofilms that protect them from their environment, making them difficult to remove. Treatment is further complicated by a global rise of antimicrobial resistance. These protective mechanisms make treatment of prosthetic joint infection increasingly complex. Non-contact induction heating is an upcoming technology that uses heat to eradicate bacteria that are present on the surface of metallic implants. This study aims to provide insight into the feasibility of using non-contact induction heating on metallic implants that are in direct contact with other biomaterials, such as coatings composed of hydroxyapatite and bone cement composed of poly (methyl methacrylate) (PMMA). Methods Characterisation of hydroxyapatite coatings and adhesion strength tests were conducted according to standards set by the International Organisation for Standardisation (ISO 13779-2). The fixation strength of acrylic bone cement was tested according to an adapted method from ISO. Results It was found that non-contact induction heating did not significantly affect the adhesion strength of hydroxyapatite coatings. In contrast to hydroxyapatite coatings, acrylic bone cement softened temporarily as the temperature exceeded the glass transition temperature (83.38 ± 10.88°C). However, the induction heating temperature had no significant effect on the fixation strength after the cement was allowed to cool down. Conclusion This study shows the feasibility of using non-contact induction heating up to 80°C when bone cement or ceramic coatings are present in contact with infected metallic implants.

Mapping Staphylococcus aureus at Early and Late Stages of Infection in a Clinically Representative Hip Prosthetic Joint Infection Rat Model.

Prosthetic joint infection (PJI) continues to be a devastating complication following total joint replacement surgeries where Staphylococcus aureus is the main offending organism. To improve our understanding of the disease pathogenesis, a histological analysis of infected peri-implant tissue in a hip PJI rat model was utilized to assess S. aureus spread and tissue reaction at early and late stages of infection. Sprague-Dawley rats were used and received a left cemented hip hemiarthroplasty using a 3D-printed titanium femoral stem. The rats received an intra-articular injection of S. aureus Xen36. These infected rats were sacrificed either at 3 days post-infection (early-stage infection) or at 13-days post-infection (late-stage infection). The femoral and acetabular tissues of all animals were harvested at euthanasia. Histological analysis for the harvested tissue was performed using immunohistochemistry, hematoxylin and eosin, as well as Masson's trichrome stains. Histological examination revealed significant quantitative and qualitative differences in peri-implant tissue response to infection at early and late stages. This hip PJI rat model identified clear histologic differences between early and late stages of S. aureus infection and how quickly bacterial infiltration could occur. These findings can provide insight into why certain surgical strategies like debridement and antibiotics may be associated with high failure rates.

Comparative effectiveness of neuraxial versus general anesthesia in total joint replacement surgery: an updated retrospective analysis using more recent data

IntroductionOver a decade ago, our study group showed improved outcomes among total hip/knee arthroplasty (THA/TKA) patients given neuraxial versus general anesthesia. As the use of neuraxial anesthesia has increased and...

Effect of various admixtures on selected mechanical properties of medium viscosity bone cements: Part 3 – Glassy carbon

Bone cements based on poly methyl-methacrylate (PMMA) are among the most widely used polymer composites in orthopaedic surgery. They play a key role in fixing the endoprosthesis with the bone, and, as such, are the weakest link in total joint replacement (TJR) surgeries. A fast, premature decrease in the mechanical properties of PMMA in an aggressive environment, such as the human body, can lead to TJR loosening, which results in the necessity for revision surgery. In recent years researchers have undertaken studies on the possibility of enhancing the mechanical properties of PMMA by adding various admixtures in different concentrations. In this study we present the results of the mechanical properties of samples made of the commercially available and widely used in orthopaedic surgery PMMA bone cement (Palamed® Heraeus) that was admixed with glassy carbon (GC) using different concentrations. All samples were subjected to compression testing. Compression reflects the load mechanism acting on PMMA in the human body after TJR implantation. The study involved comparing selected mechanical parameters of both samples prepared according to the manufacturer’s instructions and samples prepared with the addition of GC with grain sizes of 0.4–12 μm and 20–50 μm. Although this material can potentially increase the mechanical strength of PMMA, serious contamination with GC can lead to PMMA polymerization impairment due to the thermal properties of GC and, consequently, affect the mechanical properties of PMMA. GC was added in the following w/w concentrations: 1, 2, 3, 5, 8 and 10 %. Results revealed a significant decrease in the compression strength of PMMA following the addition of 20–50 μm GC, which resulted from the disturbances in standard polymerization process conditions (time and temperature). Interestingly, the addition of 0.4–12 μm GC did not affect significantly the compressive strength of the material in the tested range of concentration.

Preoperative prediction model for risk of readmission after total joint replacement surgery: a random forest approach leveraging NLP and unfairness mitigation for improved patient care and cost-effectiveness

BackgroundThe Center for Medicare and Medicaid Services (CMS) imposes payment penalties for readmissions following total joint replacement surgeries. This study focuses on total hip, knee, and shoulder arthroplasty procedures as they account for most joint replacement surgeries. Apart from being a burden to healthcare systems, readmissions are also troublesome for patients. There are several studies which only utilized structured data from Electronic Health Records (EHR) without considering any gender and payor bias adjustments.MethodsFor this study, dataset of 38,581 total knee, hip, and shoulder replacement surgeries performed from 2015 to 2021 at Novant Health was gathered. This data was used to train a random forest machine learning model to predict the combined endpoint of emergency department (ED) visit or unplanned readmissions within 30 days of discharge or discharge to Skilled Nursing Facility (SNF) following the surgery. 98 features of laboratory results, diagnoses, vitals, medications, and utilization history were extracted. A natural language processing (NLP) model finetuned from Clinical BERT was used to generate an NLP risk score feature for each patient based on their clinical notes. To address societal biases, a feature bias analysis was performed in conjunction with propensity score matching. A threshold optimization algorithm from the Fairlearn toolkit was used to mitigate gender and payor biases to promote fairness in predictions.ResultsThe model achieved an Area Under the Receiver Operating characteristic Curve (AUROC) of 0.738 (95% confidence interval, 0.724 to 0.754) and an Area Under the Precision-Recall Curve (AUPRC) of 0.406 (95% confidence interval, 0.384 to 0.433). Considering an outcome prevalence of 16%, these metrics indicate the model’s ability to accurately discriminate between readmission and non-readmission cases within the context of total arthroplasty surgeries while adjusting patient scores in the model to mitigate bias based on patient gender and payor.ConclusionThis work culminated in a model that identifies the most predictive and protective features associated with the combined endpoint. This model serves as a tool to empower healthcare providers to proactively intervene based on these influential factors without introducing bias towards protected patient classes, effectively mitigating the risk of negative outcomes and ultimately improving quality of care regardless of socioeconomic factors.

Effect of non-contact induction heating on HA coatings and bone cement, an ex vivo study

Background Prosthetic joint infection is a serious complication that can arise after total joint replacement surgery. When bacteria colonise an orthopaedic implant, they form biofilms that protect them from their environment, making them difficult to remove. Treatment is further complicated by a global rise of antimicrobial resistance. These protective mechanisms make treatment of prosthetic joint infection increasingly complex. Non-contact induction heating is an upcoming technology that uses heat to eradicate bacteria that are present on the surface of metallic implants. This study aims to provide insight into the feasibility of using non-contact induction heating on metallic implants that are in direct contact with other biomaterials, such as coatings composed of hydroxyapatite and bone cement composed of poly (methyl methacrylate) (PMMA). Methods Characterisation of hydroxyapatite coatings and adhesion strength tests were conducted according to standards set by the International Organisation for Standardisation (ISO 13779-2). The fixation strength of acrylic bone cement was tested according to an adapted method from ISO. Results It was found that non-contact induction heating did not significantly affect the adhesion strength of hydroxyapatite coatings (p=0.697). In contrast to hydroxyapatite coatings, acrylic bone cement softened temporarily as the temperature exceeded the glass transition temperature (83.38 ± 10.88°C). However, the induction heating temperature had no significant effect on the fixation strength after the cement was allowed to cool down (p=0.535). Conclusion This study shows the feasibility of using non-contact induction heating up to 80°C when bone cement or ceramic coatings are present in contact with infected metallic implants.

Pre-Operative Adiposity and Synovial Fluid Inflammatory Biomarkers Provide a Predictive Model for Post-Operative Outcomes Following Total Joint Replacement Surgery in Osteoarthritis Patients

A proportion of osteoarthritis (OA) patients are unsatisfied with post-operative outcomes following total joint replacement surgery (TJR), with insufficient pain relief or poor functional improvement. Predicting those who will have poor outcomes would be beneficial for patients and clinicians. The aim of this study was to determine the relationship between baseline anthropometric data and the concentration of pre-operative serum and peri-operative synovial fluid (SF) cytokines and 7-month post-operative outcomes in a cohort of knee and hip OA patients. 160 OA patients were recruited who were scheduled for TJR. The concentration of 24 cytokines was measured in blood and SF by multiplex assay. EQ5D index health status was assessed pre-operatively and at 7 months post-operatively. 13% of patients were identified as non-responders based on EQ5D index. Compared to responders, non-responders were of higher body mass index (BMI), had greater waist and hip circumference, and had higher levels of SF leptin but lower levels of SF resistin (p < 0.05). Linear regression analysis found a significant but weak relationship between pre-operative body weight and post-operative response (ΔEQ5D index; r = 0.222, p = 0.049). The combination of body weight with SF amphiregulin and SF IL-6 provided an improved predictive model of post-operative response (r = 0.470, p = 0.035).

Muscle and joint mechanics during maximum force biting following total temporomandibular joint replacement surgery

Total temporomandibular joint replacement (TMJR) surgery is the established treatment for severe temporomandibular joint disorders. While TMJR surgery is known to increase mouth-opening capacity, reduce pain and improve quality of life, little is known about post-surgical jaw function during activities of daily living such as biting and chewing. The aim of this study was to use subject-specific 3D bite force measurements to evaluate the magnitude and direction of joint loading in unilateral total TMJR patients and compare these data to those in healthy control subjects. An optoelectronic tracking system was used to measure jaw kinematics while biting a rubber sample for 5 unilateral total TMJR patients and 8 controls. Finite element simulations driven by the measured kinematics were employed to calculate the resultant bite force generated when compressing the rubber between teeth during biting tasks. Subject-specific musculoskeletal models were subsequently used to calculate muscle and TMJ loading. Unilateral total TMJR patients generated a bite force of 249.6 ± 24.4 N and 164.2 ± 62.3 N when biting on the contralateral and ipsilateral molars, respectively. In contrast, controls generated a bite force of 317.1 ± 206.6 N. Unilateral total TMJR patients biting on the contralateral molars had a significantly higher lateral TMJ force direction (median difference: 63.6°, p = 0.028) and a significantly lower ratio of working TMJ force to bite force (median difference: 0.17, p = 0.049) than controls. Results of this study may guide TMJ prosthesis design and evaluation of dental implants.

Factors Influencing Patient Satisfaction with Total Joint Replacement Surgery.

Replacement arthroplasty surgery is a surgical procedure that is needed to restore the activity of a joint. Patient satisfaction regarding arthroplasty surgery is influenced by post-operative complication rate, ability to afford care, and quality of interaction. In this study, we assessed patients' postoperative complications, mobility, and pain management as proxies for their overall satisfaction with total joint replacement (TJR). An anonymous web-based survey was conducted for patients who had undergone any total joint replacement surgery in the US. Respondents were adults living in the United States. 180 individuals met the inclusion criteria and responded to the survey. Age, education, gender, and race were fitted against the patient satisfaction level with the surgeon. While education [P=0.4720], gender [P=0.5097 ], and race [P=0.8183] were not significant, age in years [P=0.02340] was predictive of overall satisfaction levels [R2=0.0213]. When controlling for BMI, infection [P=0.0164], nerve damage [P=0.0250], delayed healing [P=0.0024], hematoma [P=0.0497], were more likely to occur in participants who have had a knee replacement, as compared to shoulder and hip replacement surgery. When controlling for mobility before surgery vs.mobility after surgery [P=0.0114], patients who selected the highest level of mobility before surgery were likely to select the highest level of mobility after surgery. Medicaid, Medicare, private insurance, employer-based insurance, and no insurance were fitted against the patient's self-reported difficulty in paying for their treatment/care. Although employer-based insurance [P=0.0790] was not significant in predicting difficulty in paying for the surgery, patients with Medicaid [P=0.0280], Medicare [P=0.0200], or private insurance [P=0.0343] did. In this cohort, older patients were associated with having improved satisfaction with the surgeon who performed their joint replacement. Complications were higher in patients who underwent a knee arthroplasty compared to a shoulder or hip arthroplasty.

How a nursing navigation role enhances patient recovery across Orthopedic Integrated Pathways

Introduction: Our academic urban institution developed an integrated care pathway that has significantly improved patient transitions to outpatient rehabilitation after total joint replacement (TJR) and as patients requested, supports their earlier discharge from a hospital to home to recover. Early recovery at home has identified a need for care navigation, particularly for patients with a higher complexity of medical and social issues. Implementation of a nursing role for care navigation into our existing integrated pathways would provide support for patients receiving TJR surgery ensuring better coordination of services in their community. 
 Aims, Objectives and Methodology: Our objective was to evaluate an IC nursing lead (ICL) role embedded in our existing orthopedic TJR integrated pathway to support “extended” care patients to safely discharge home. Process mapping sessions conducted in 2019-20, that included key stakeholders and patient partners, identified gaps in communication and care coordination before and after surgery affecting overall patient experience and surgical recovery.
 “Extended” care patients were identified by the orthopedic care team using a standardized referral form developed in conjunction with the ICL. Patients were contacted 1-2 weeks pre-surgery and supported at various pre-operative time points with care coordination. An in-person visit with the patient occurred on the day of surgery and prior to discharge from hospital. A standard 24-hr post-op phone call was completed once the patient returned home. The ICL could be engaged by the patient or care team at any point across the TJR journey (between consent and day of surgery, acute inpatient stay, and up to 90 days post-surgery.
 Key Findings: The ICL role, piloted in March 2022, started with gradual enrolment of patients across 2 arthroplasty surgeons. By August 2022, all 6 arthroplasty care teams (surgeons, physiotherapist practitioners, fellows, physician assistants and admins) were committed to this model of care. ICL patients were 41% male and 59% female ranging in age from 50-92 (mean age of 78). Inpatient pts represented 94% (ALOS 1-2 days). Discharge (DC) disposition patterns aligned with existing best practice guidelines. Discharge coordination made up the bulk of support (82%) provided by the ICL. Other key themes and interventions included emotional reassurance (32%), education/expectation setting (30%), information on community resources and services (18%), arrangement of homecare (6%), other miscellaneous questions (5%). The average time spent for care coordination was 90 mins per patient over the 90 day period.
 Qualitative report from ICL patients revealed improved patient experience with the degree of detail and support provided. "I'm so glad I can call you. I don't always know who to talk to when I have questions". "It's so good to have someone pick up the phone when I need an answer when everything is closed".
 Conclusions: Early findings highlight the benefits of an ICL in improving care quality of patients undergoing TJR and enabling coordinated transitions post discharge from hospital through to their recovery at home. As hospital stays for TJR becoming exceedingly shorter this type of role becomes even more critical, especially with increased patient needs in the aftermath of COVID-19.
 

Joint Replacement Technology in the Ambulatory Surgery Center: Current and Future Applications.

Total joint replacement (TJR) surgery in the ambulatory surgery centers (ASCs) has grown significantly over the past several years, along with the ability to improve the value of care. Standardization of high-quality, perioperative care is pivotal to the success of a TJR ASC program. As surgeons are experiencing increasing overhead with decreasing reimbursement, technology integration can provide major advantages. In this article, we will therefore highlight several examples of technologies that are changing the field and improving care in the preoperative, intraoperative, and postoperative settings.

Use of analgesics before and after total joint replacement in working-age Japanese patients with knee and hip osteoarthritis: A retrospective database study

BackgroundPatterns of analgesic use before and after total joint replacement (TJR) in patients with knee/hip osteoarthritis (OA) is not well reported. MethodsThis retrospective longitudinal analysis used JMDC claims data of patients who underwent knee/hip replacement surgery from 2010 to 2019. Primary outcome was proportion of patients using analgesics pre-surgery, immediately post-surgery, and in post-surgery period. Factors affecting post-surgery analgesic withdrawal and opioid prescriptions were assessed using logistic regression. ResultsOf all (N = 3168) patients, those with knee OA (91.1 %) and hip OA (82.5 %) used analgesics pre-surgery, and 96.1 % with knee OA and 84.9 % with hip OA required analgesics even 3 months post-surgery. NSAIDs were most commonly used pre- and post-surgery in both OA groups. Before surgery, 15.6 % (knee OA) and 13.7 % of patients (hip OA) used weak opioids, and 23.1 % (knee OA) and 10.5 % (hip OA) of patients continued them post-surgery. Strong opioid use was noted in 2.2 % and 1.2 % of patients pre-surgery, and 5.8 % and 3.4 % of patients post-surgery in the knee and hip OA groups, respectively. Using pre-operative oral NSAIDs (odds ratio [OR]:0.56; 95 % confidence interval [CI]:0.44–0.72) and weak opioids (OR:0.58; 95 % CI:0.38–0.87) associated with withdrawal of post-surgery analgesics in patients with hip OA, and using intra-articular hyaluronic acid pre-surgery (OR:0.45; 95 % CI:0.21–0.97) was significant in patients with knee OA. Using weak (OR:4.59; 95 % CI:3.44–6.13) and strong opioids (OR:2.48; 95 % CI:1.01–6.07) pre-surgery associated with post-operative opioid use in patients with hip OA, and weak opioid use was significant in patients with knee OA (OR:7.00; 95 % CI:4.65–10.54). ConclusionThis study reported difference in analgesic use before and after TJR, and that many patients required analgesics even 3 months after TJR surgery in Japan. Pre-operative analgesic use associated with continued use after surgery. Optimal pain management before and immediately after TJR is important to reduce post-operative analgesic use, especially opioids.

Epigenetic regulation of 15-lipoxygenase-1 expression in human chondrocytes by promoter methylation.

15-Lipoxygenase-1 (15-LOX-1) catalyzes the biosynthesis of many anti-inflammatory and immunomodulatory lipid mediators and was reported to have protective properties in several inflammatory conditions, including osteoarthritis (OA). This study was designed to evaluate the expression of 15-LOX-1 in cartilage from normal donors and patients with OA, and to determine whether it is regulated by DNA methylation. Cartilage samples were obtained at autopsy from normal knee joints and from OA-affected joints at the time of total knee joint replacement surgery. The expression of 15-LOX-1 was evaluated using real-time polymerase chain reaction (PCR). The role of DNA methylation in 15-LOX-1 expression was assessed using the DNA methyltransferase inhibitor 5-Aza-2'-desoxycytidine (5-Aza-dC). The effect of CpG methylation on 15-LOX-1 promoter activity was evaluated using a CpG-free luciferase vector. The DNA methylation status of the 15-LOX-1 promoter was determined by pyrosequencing. Expression of 15-LOX-1 was upregulated in OA compared to normal cartilage. Treatment with 5-Aza-dC increased 15-LOX-1 mRNA levels in chondrocytes, and in vitro methylation decreased 15-LOX-1 promoter activity. There was no difference in the methylation status of the 15-LOX-1 gene promoter between normal and OA cartilage. The expression level of 15-LOX-1 was elevated in OA cartilage, which may be part of a repair process. The upregulation of 15-LOX-1 in OA cartilage was not associated with the methylation status of its promoter, suggesting that other mechanisms are involved in its upregulation.

Zucker Diabetic-Sprague Dawley Rats Have Impaired Peri-Implant Bone Formation, Matrix Composition, and Implant Fixation Strength.

An increasing number of patients with type 2 diabetes (T2DM) will require total joint replacement (TJR) in the next decade. T2DM patients are at increased risk for TJR failure, but the mechanisms are not well understood. The current study used the Zucker Diabetic-Sprague Dawley (ZDSD) rat model of T2DM with Sprague Dawley (SPD) controls to investigate the effects of intramedullary implant placement on osseointegration, peri-implant bone structure and matrix composition, and fixation strength at 2 and 10 weeks post-implant placement. Postoperative inflammation was assessed with circulating MCP-1 and IL-10 2 days post-implant placement. In addition to comparing the two groups, stepwise linear regression modeling was performed to determine the relative contribution of glucose, cytokines, bone formation, bone structure, and bone matrix composition on osseointegration and implant fixation strength. ZDSD rats had decreased peri-implant bone formation and reduced trabecular bone volume per total volume compared with SPD controls. The osseointegrated bone matrix of ZDSD rats had decreased mineral-to-matrix and increased crystallinity compared with SPD controls. Osseointegrated bone volume per total volume was not different between the groups, whereas implant fixation was significantly decreased in ZDSD at 2 weeks but not at 10 weeks. A combination of trabecular mineral apposition rate and postoperative MCP-1 levels explained 55.6% of the variance in osseointegration, whereas cortical thickness, osseointegration mineral apposition rate, and matrix compositional parameters explained 69.2% of the variance in implant fixation strength. The results support the growing recognition that both peri-implant structure and matrix composition affect implant fixation and suggest that postoperative inflammation may contribute to poor outcomes after TJR surgeries in T2DM patients. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Does a consumer co-designed infographic increase knowledge of physical activity after total knee joint replacement? A randomised controlled trial.

To determine if a consumer co-designed infographic increased knowledge of physical activity and self-efficacy for exercise after total knee joint replacement surgery. Forty-four adults with primary knee joint replacement surgery were recruited from a public and a private hospital in Melbourne, Australia. Participants were randomly allocated to an experimental or control group. The experimental group received a consumer co-designed infographic. All participants received usual care. Primary outcome measures were knowledge of physical activity and self-efficacy for exercise. Outcomes were administered at baseline, week 1 and week 6. Semi-structured interviews with experimental group participants explored the acceptability, implementation and efficacy of the infographic. There were no between-group differences for knowledge of physical activity at week 1 (MD -0.02units, 95% CI -0.9 to 0.9) or week 6 (MD 0.01units, 95% CI -0.9 to 0.9). Self-efficacy for exercise increased at week 1 (MD 14.2units, 95% CI 2.9-25.4) but was not sustained. Qualitative data showed that the infographic was embraced by some participants but not by others. A consumer co-designed infographic did not improve knowledge of physical activity but may have had a short-term positive effect on self-efficacy for exercise after knee joint replacement. Trial registration ACTRN12621000910808.

Biocomposites containing poly(lactic acid) and chitosan for 3D printing – Assessment of mechanical, antibacterial and in vitro biodegradability properties

New bone repair materials are needed for treatment of trauma- and disease-related skeletal defects as they still represent a major challenge in clinical practice. Additionally, new strategies are required to combat orthopedic device-related infections (ODRI), given the rising incidence of total joint replacement and fracture fixation surgeries in increasingly elderly populations. Recently, the convergence of additive manufacturing (AM) and bone tissue engineering (BTE) has facilitated the development of bone healthcare to achieve personalized three-dimensional (3D) scaffolds. This study focused on the development of a 3D printable bone repair material, based on the biopolymers poly(lactic acid) (PLA) and chitosan. Two different types of PLA and chitosan differing in their molecular weight (MW) were explored. The novel feature of this research was the successful 3D printing using biocomposite filaments composed of PLA and 10 wt% chitosan, with clear chitosan entrapment within the PLA matrix confirmed by Scanning Electron Microscopy (SEM) images. Tensile testing of injection molded samples indicated an increase in stiffness, compared to pure PLA scaffolds, suggesting potential for improved load-bearing characteristics in bone scaffolds. However, the potential benefit of chitosan on the biocomposite stiffness could not be reproduced in compression testing of 3D printed cylinders. The antibacterial assays confirmed antibacterial activity of chitosan when dissolved in acetic acid. The study also verified the biodegradability of the scaffolds, with a process producing an acidic environment that could potentially be neutralized by chitosan. In conclusion, the study indicated the feasibility of the proposed PLA/chitosan biocomposite for 3D printing, demonstrating adequate mechanical strength, antibacterial properties and biodegradability, which could serve as a new material for bone repair.

FTP4.9 An audit to measure if >5% reduction in weight occurred, as recommended by the National Institute of Health and Clinical Excellence (NICE), for patients suffering from osteoarthritis before their scheduled total joint replacement surgery, at Darwen Health Link Surgery

Abstract Aim Osteoarthritis causes damage to synovial joints, manifesting as pain, loss of function, and disability. A high BMI is correlated with an increased incidence of osteoarthritis, for which NICE recommends a >5% (ideally >10%) decrease in baseline weight to improve pain and functionality. This audit aims to measure Darwen Health Link’s adherence to NICE guidelines 226 “Osteoarthritis in over 16s: diagnosis and management” for the management of osteoarthritis patients regarding weight-loss. Method This audit analysed 15 osteoarthritis patients with a BMI>30 who underwent total joint replacements from November 2021 to November 2022. Patient records were analysed for their weight management from 3-12 months prior to surgery, up till their surgery period to assess: if weight-loss advice was provided and if >5% weight-loss took place. Standards were designated per clinician recommendations and NICE guidelines. Results All osteoarthritic patients (n=15) were given weight-loss advice at presentations before surgery. However, only 20% (n=3) of patients lost >5% of their baseline weight before their joint replacements, against the 50% standard. Therefore, interventions to improve weight-loss in patients and clinician guidance were implemented. These include a targeted poster, detailed weight-loss advice packs for patients, and clinician education about weight-loss programmes available locally. Conclusion The first part of the audit indicates suboptimal performance by Darwen Health Link. Their performance will be re-audited in 3 months post-interventional implementation. Reducing osteoarthritis’s burden on patients in primary care can significantly reduce pain and the need for surgery.

Kinematics of the jaw following total temporomandibular joint replacement surgery

Total temporomandibular joint (TMJ) replacement surgery aims to improve mandibular function, reduce pain and enhance quality of life in patients suffering from end-stage TMJ disorders. Traditional post-operative jaw evaluation is carried out using measurement of maximum interincisal opening distance; however, this can correlate poorly to joint function. The present study aimed to evaluate three-dimensional (3D) jaw motion during border movements and chewing in unilateral total TMJ replacement patients and healthy controls. Motion analysis experiments were performed on six unilateral total TMJ replacement patients and ten age-matched healthy controls. Subject-specific motion tracking plates worn by each participant were registered to CT scans of each participant’s skull and mandible to enable anatomical mandibular kinematics measurement using an optoelectronic system. Participants performed 15 repetitions of maximal opening, protrusion, lateral excursions, and chewing cycles. Total TMJ replacement patients had significantly smaller incisal displacements at maximum mouth opening relative to the controls (median difference: 7.1 mm, p = 0.002) and decreased anterior translation of the prosthetic condyle (median difference: 10.5 mm, p = 0.002). When TMJ replacement subjects chewed using their contralateral molars, there was a significant increase in inferior condylar translation of the non-working condyle (median difference: 9.7 mm, p = 0.016). This study found that unilateral total TMJ replacement surgery was associated with mouth opening capacity within the range of healthy individuals, but reduced anterior movement of the prosthetic condyle and restricted protrusion and lateral excursions. The results provide future direction for prosthetic TMJ design to enhance postsurgical implant functionality and improve long-term clinical outcomes for prosthesis recipients.

Insufficiency of collagenases in establishment of primary chondrocyte culture from cartilage of elderly patients receiving total joint replacement.

Background Collagenases are frequently used in chondrocyte isolation from articular cartilage. However, the sufficiency of this enzyme in establishing primary human chondrocyte culture remains unknown. Methods Cartilage slices shaved from femoral head or tibial plateau of patients receiving total joint replacement surgery (16 hips, 8 knees) were subjected to 0.02% collagenase IA digestion for 16h with (N = 19) or without (N = 5) the pre-treatment of 0.4% pronase E for 1.5h. Chondrocyte yield and viability were compared between two groups. Chondrocyte phenotype was determined by the expression ratio of collagen type II to I. The morphology of cultured chondrocytes was monitored with a light microscope.Results Cartilage with pronase E pre-treatment yielded significantly higher chondrocytes than that without the pre-treatment (3,399 ± 1,637 cells/mg wet cartilage vs. 1,895 ± 688 cells/mg wet cartilage; P = 0.0067). Cell viability in the former group was also significantly higher than that in the latter (94% ± 2% vs. 86% ± 6%; P = 0.03). When cultured in monolayers, cells from cartilage with pronase E pre-treatment grew in a single plane showing rounded shape while cells from the other group grew in multi-planes and exhibited irregular shape. The mRNA expression ratio of collagen type II to I was 13.2 ± 7.5 in cells isolated from cartilage pre-treated with pronase E, indicating a typical chondrocyte phenotype. Conclusions Collagenase IA was not sufficient in establishing primary human chondrocyte culture. Cartilage must be treated with pronase E prior to collagenase IA application.