Aims. Single-shot adductor canal block (ACB) after total knee arthroplasty (TKA) for postoperative analgesia is a common modality. Patients can experience breakthrough pain when the effect of ACB wears off. Local anaesthetic infusion through an intra-articular catheter (IAC) can help manage breakthrough pain after TKA. We hypothesized that combined ACB with ropivacaine infusion through IAC is associated with better pain relief compared to ACB used alone. Methods. This study was a prospective double-blinded placebo-controlled randomized controlled trial to compare the efficacy of combined ACB+ IAC-ropivacaine infusion (study group, n = 68) versus single-shot ACB+ intra-articular normal saline placebo (control group, n = 66) after primary TKA. The primary outcome was assessment of pain, using the visual analogue scale (VAS) recorded at 6, 12, 24, and 48 hours after surgery. Secondary outcomes included active knee ROM 48 hours after surgery and additional requirement of analgesia for breakthrough pain. Results. The study group (mean visual analogue scale (VAS) pain score of 5.5 (SD 0.889)) experienced significant reduction in pain 12 hours after surgery compared to the control group (mean VAS 6.62 (SD 1.356); mean difference = 1.12, 95% confidence interval (CI) -1.46 to 0.67; p < 0.001), and pain scores on postoperative day (POD) 1 and POD-2 were lower in the study group compared to the control group (mean difference in VAS pain = 1.04 (-1.39 to -0.68, 95% CI, p < 0.001). Fewer patients in the study group (0 vs 3 in the control group) required additional analgesia for breakthrough pain, but this was not statistically significant. The study group had significantly increased active knee flexion (mean flexion 86.4° (SD 7.22°)), compared to the control group (mean 73.86° (SD 7.88°), mean difference = 12.54, 95% CI 9.97 to 15.1; p < 0.014). Conclusion. Combined ACB+ ropivacaine infusion via IAC is a safe, reproducible analgesic modality after primary TKA, with superior analgesia compared to ACB alone. Further large volume trials are warranted to generate evidence on clinical significance on analgesia after TKA. Cite this article: Bone Jt Open 2021;2(12):1082–1088

The aim of this study was to compare the efficacy of a hyaluronic acid (HA) supplement and a local anaesthetic (Bupivacaine) at providing early and short-term post-operative anagesic control following knee arthroscopy. Patients were randomised to receive either 10mls of 0.5% Bupivacaine or 10mls of HA into the joint immediately after completion of surgery. WOMAC and Tegner-Lysholm scores were obtained at baseline then at 1, 2, and 6-weeks post surgery. VAS pain scores were obtained at baseline; 1 and 24-hours; and 1, 2 and 6 weeks following surgery. 49 patients received intra-articular Bupivacaine and 49 HA. There was no statistical difference in any of the outcome measures (WOMAC, Tegner-Lysholm, VAS pain scores) at any time point between the groups overall. Patients with grade III-IV chondral defects that received HA reported significantly lower VAS pain scores at rest and movement at all time points. Use of Bupivacaine and HA intra-articular injection results in equivalent analgesic control in the immediate post-operative period and first six-weeks following surgery when administered immediately at the end of knee arthroscopy. Utilizing HA following knee arthroscopy does not sacrifice analgesic control and minimises exposure to chondrotoxic agents. Selective use of HA may improve pain-control in those with advanced chondral defects

Introduction

Opioid abuse is a national epidemic. Traditional pain management after total knee arthroplasty (TKA) relied heavily on opioids. The evidence that in-hospital multimodal pain management (MMPM) is more effective than opioid-only analgesia is overwhelming. There has been little focus on post-discharge pain management. The purpose of this study was to determine whether MMPM after TKA could reduce opioid consumption in the 30-day period after hospital discharge.

Aims

Enhanced perioperative protocols have significantly improved patient recovery following primary total knee arthroplasty (TKA). Little has been investigated the effectiveness of these protocols for revision TKA (RTKA). We report on a matched group of aseptic revision and primary TKA patients treated with an identical pain and rehabilitation programmes.

Abstract. Introduction. Adverse reactions to pain medication and pain can delay discharge after outpatient knee arthroplasty (TKA). Pharmacogenomics is an emerging tool that might help reduce adverse events by tailoring medication use based on known genetic variations in the CYP genes determining drug metabolism. This study was undertaken to evaluate whether pre-operative pharmacogenomic testing could optimize peri-operative pain management in patients undergoing total knee arthroplasty (TKA). Methods. This prospective, randomized study was performed in adults undergoing primary TKA. Patients in the experimental group underwent pre-operative pharmacogenomic evaluation and medication adjustments. Medications were not optimized for control patients. The Overall Benefit of Analgesic Score (OBAS) at 24 hours post-op was the primary outcome. Postoperative pain scores (VAS scale), total opioid use, time in recovery, and time to discharge were also compared. Results. 76 patients enrolled. 93% of patients had a poor-intermediate phenotype for at least one of four CYP genes. OBAS did not differ significantly between the two groups (4.2 control vs. 4.7 experimental; 95% CI −1.1 to 2.1) and was below the minimum clinically important difference of 2.0 points. Furthermore, there were no differences in any OBAS subscale including pain, satisfaction, or nausea. There were no differences in time in the recovery area or to discharge from hospital, or narcotic use. Conclusions. Despite many patients having a poor-intermediate phenotype for a CYP gene, pharmacogenomic testing prior to TKA and medication adjustment did not improve anesthesia or pain management outcomes, time to discharge or mean total opioid use after surgery

Abstract. Introduction. The effectiveness of single intra-articular injections of polyacrylamide hydrogel (iPAAG) and hyaluronic acid (HA) was compared in subgroups of participants from an RCT based on baseline age, BMI or Kellgren-Lawrence (KL) grade. Methodology. 239 participants were randomised to 6 mL iPAAG (Arthrosamid; n=119) or 6 mL HA (Synvisc-One; n=120). Participants continued analgesics (except 48 hours prior to visits) and non-pharmacological therapy. Topical therapies and intra-articular corticosteroids were not allowed. Pre-specified subgroup analyses (age: <70 years, ≥70 years; BMI: normal, overweight, obese; KL grade: 2, 3, 4, 2–3) of change from baseline in WOMAC pain subscale at 52 weeks were based on the least squares means for the treatment-by-week interaction effect using a mixed model for repeated measurement with a restricted maximum likelihood-based approach. Results. Across all patients, change from baseline in WOMAC pain subscale in the iPAAG group was non-inferior to HA at 26 weeks and approached superiority (p=0.0572) at 52 weeks. Treatment differences for change from baseline in WOMAC pain subscale in favour of iPAAG over HA were statistically significant for the age <70 years (p=0.019), BMI normal (p=0.011) and KL grade 2–3 (p=0.033) subgroups. Treatment differences for all other subgroups favoured iPAAG, except for KL grade 4 which favoured HA, without reaching statistical significance. Conclusion. iPAAG approached superiority to HA across all participants at 52weeks, but demonstrated statistical superiority in participants with normal BMI, participants <70 years old or participants with KL score 2–3. iPAAG represents a useful alternative to HA for the treatment of knee OA

Aims. The aim of this study was to compare the clinical outcomes of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) during the first six weeks and at one year postoperatively. Methods. A per protocol analysis of 76 patients, 43 of whom underwent TKA and 34 of whom underwent bi-UKA, was performed from a prospective, single-centre, randomized controlled trial. Diaries kept by the patients recorded pain, function, and the use of analgesics daily throughout the first week and weekly between the second and sixth weeks. Patient-reported outcome measures (PROMs) were compared preoperatively, and at three months and one year postoperatively. Data were also compared longitudinally and a subgroup analysis was conducted, stratified by preoperative PROM status. Results. Both operations were shown to offer comparable outcomes, with no significant differences between the groups across all timepoints and outcome measures. Both groups also had similarly low rates of complications. Subgroup analysis for preoperative psychological state, activity levels, and BMI showed no difference in outcomes between the two groups. Conclusion. Robotic arm-assisted, cruciate-sparing bi-UKA offered similar early clinical outcomes and rates of complications to a mechanically aligned TKA, both in the immediate postoperative period and up to one year following surgery. Further work is required to identify which patients with osteoarthritis of the knee will derive benefit from a cruciate-sparing bi-UKA. Cite this article: Bone Joint J 2021;103-B(10):1561–1570

Abstract. Objectives. To determine the effectiveness of LIA compared to ACB in providing pain relief and reducing opiates usage in hamstring graft ACL reconstructions. Materials and Methods. In a consecutive series of hamstring graft ACL reconstructions, patients received three different regional and/or anaesthetic techniques for pain relief. Three groups were studied: group 1: general anaesthetic (GA)+ ACB (n=38); group 2: GA + ACB + LIA (n=31) and group 3: GA+LIA (n=36). ACB was given under ultrasound guidance. LIA involved infiltration at skin incision site, capsule, periosteum and in the hamstring harvest tunnel. Analgesic medications were similar between the three groups as per standard multimodal analgesia (MMA). Patients were similar in demographics distribution and surgical technique. The postoperative pain and total morphine requirements were evaluated and recorded. The postoperative pain was assessed using the visual analogue scores (VAS) at 0hrs, 2hrs, 4hrs, weight bearing (WB) and discharge (DC). Results. There was no statistically significant difference in opiates intake amongst the three groups. When comparing VAS scores; there were no statistical difference between the groups at any of the time intervals that VAS was measured. However, the GA+LIA group hospital's LOS (m=2.31hrs, SD=0.75) was almost half that of GA+ACB group (m=4.24hrs, SD=1.08); (conditions t(72)=8.88; p=0.000). There was no statistical significance in the incidence of adverse effects amongst the groups. Conclusion. The LIA technique provided equally good pain relief following hamstring graft ACL reconstructions when compared to ACB, while allowing for earlier rehabilitation, mobilisation and discharge

Introduction. Insufficient pain control following lower extremity surgery can increase length of stay, readmission rates, and impair postoperative outcome. It has been shown that CYP2D6 genotypes predict function of the enzyme responsible for conversion of hydrocodone to hydromorphone (active metabolite) and plasma concentration of hydromorphone best predicted analgesic response. Purpose of this study was to evaluate relationship of CYP2D6 genotypes, drug-drug interactions, and plasma drug concentrations in patients undergoing lower extremity surgery. Methods. A prospective cohort of 271 orthopedic patients undergoing lower extremity surgery including TKA, THA and trauma were queried. Patients treated with hydrocodone were enrolled and tested for plasma concentrations of hydrocodone and hydromorphone. CYP2D6 genotyping was performed. Medications co-administered with hydrocodone during perioperative and postoperative periods were queried. Results. Out of 271 patients enrolled, only 41 (15%) had detectable hydromorphone (i.e. >0.5 ng/mL). 86% were extensive (normal) metabolizers, 7% were intermediate metabolizers, 5% poor metabolizers and 2% were ultra rapid metabolizers. 179 subjects were not administered any inhibitors of CYP2D6 whereas 92 were on at least one inhibitor. 33 (18%) with no pharmacological inhibitors had detectable hydromorphone, whereas only 7 (7.6%) on inhibitors had hydromorphone detected above the lower limit of quantification (0.5ng/mL), p=0.033. Diphenhydramine, fluoxetine, hydralazine, duloxetine, bupropion and sertraline, were the most common CYP2D6 inhibitors co-administered with hydrocodone in this cohort. Conclusions. Patients' home medications and selection of various drugs in the postoperative setting could impact the pharmacokinetics and pharmacodynamics of hydrocodone leading to a diminished analgesic response. We conclude that health care providers should become familiar with the inhibitors of CYP2D6 to obtain the best response with the use of hydrocodone following lower extremity surgery. Additional work is required to determine the ideal opioid for an individual patient's genotype following lower extremity orthopedic surgery. For figures, tables, or references, please contact authors directly

In a randomised controlled pragmatic trial we investigated whether local infiltration analgesia would result in earlier readiness for discharge from hospital after total knee replacement (TKR) than patient-controlled epidural analgesia (PCEA) plus femoral nerve block. A total of 45 patients with a mean age of 65 years (49 to 81) received a local infiltration with a peri-articular injection of bupivacaine, morphine and methylprednisolone, as well as adjuvant analgesics. In 45 PCEA+femoral nerve blockade patients with a mean age of 67 years (50 to 84), analgesia included a bupivacaine nerve block, bupivacaine/hydromorphone PCEA, and adjuvant analgesics. The mean time until ready for discharge was 3.2 days (1 to 14) in the local infiltration group and 3.2 days (1.8 to 7.0) in the PCEA+femoral nerve blockade group. The mean pain scores for patients receiving local infiltration were higher when walking (p = 0.0084), but there were no statistically significant differences at rest. The mean opioid consumption was higher in those receiving local infiltration. The choice between these two analgesic pathways should not be made on the basis of time to discharge after surgery. Most secondary outcomes were similar, but PCEA+femoral nerve blockade patients had lower pain scores when walking and during continuous passive movement. If PCEA+femoral nerve blockade is not readily available, local infiltration provides similar length of stay and similar pain scores at rest following TKR. . Cite this article: Bone Joint J 2013;95-B:629–35

Aims. Adductor canal block (ACB) has emerged as an alternative to femoral nerve block (FNB) for analgesia after total knee arthroplasty (TKA). The optimal duration of maintenance of the ACB is still questionable. The purpose of this study was to compare the analgesic benefits and physiotherapy (PT) outcomes of single-shot ACB to two different regimens of infusion of the continuous ACB, 24-hour and 48-hour infusion. Patients and Methods. This was a prospective, randomized, unblinded study. A total of 159 American Society of Anesthesiologists (ASA) physical status I to III patients scheduled for primary TKA were randomized to one of three study groups. Three patients did not complete the study, leaving 156 patients for final analysis. Group A (n = 53) was the single-shot group (16 female patients and 37 male patients with a mean age of 63.9 years (. sd. 9.6)), group B (n = 51) was the 24-hour infusion group (22 female patients and 29 male patients with a mean age of 66.5 years (. sd. 8.5)), and group C (n = 52) was the 48-hour infusion group (18 female patients and 34 male patients with a mean age of 62.2 years (. sd. 8.7)). Pain scores, opioid requirements, PT test results, and patient-reported outcome instruments were compared between the three groups. Results. The proportion of patients reporting severe pain, defined as a pain score of between 7 and 10, on postoperative day number 2 (POD 2) were 21% for the single-shot group, 14% for the 24-hour block group, and 12% for the 48-hour block group (p = 0.05). Cumulative opioid requirements after 48 hours were similar between the groups. Functional outcomes were similar in all three groups in POD 1 and POD 2. Conclusion. There was no clear benefit of the 24-hour or 48-hour infusions over the single-shot ACB for the primary endpoint of the study. Otherwise, there were marginal benefits for keeping the indwelling catheter for 48 hours in terms of reducing the number of patients with moderate pain and improving the quality of pain management. However, all three groups had similar opioid usage, length of hospital stay, and functional outcomes. Further studies with larger sample sizes are needed to confirm these findings. Cite this article: Bone Joint J 2019;101-B:340–347

Aims. Unicompartmental knee arthroplasty (UKA) provides improved early functional outcomes and less postoperative morbidity and pain compared with total knee arthroplasty (TKA). Opioid prescribing has increased in the last two decades, and recently states in the USA have developed online Prescription Drug Monitoring Programs to prevent overprescribing of controlled substances. This study evaluates differences in opioid requirements between patients undergoing TKA and UKA. Patients and Methods. We retrospectively reviewed 676 consecutive TKAs and 241 UKAs. Opioid prescriptions in morphine milligram equivalents (MMEs), sedatives, benzodiazepines, and stimulants were collected from State Controlled Substance Monitoring websites six months before and nine months after the initial procedures. Bivariate and multivariate analysis were performed for patients who had a second prescription and continued use. Results. Patients undergoing UKA had a second opioid prescription filled 50.2% of the time, compared with 60.5% for TKA (p = 0.006). After controlling for potential confounders, patients undergoing UKA were still less likely to require a second prescription than those undergoing TKA (adjusted odds ratio (OR) 0.58, 95% confidence interval (CI) 0.42 to 0.81; p = 0.001). Continued opioid use requiring more than five prescriptions occurred in 13.7% of those undergoing TKA and 5.8% for those undergoing UKA (p = 0.001), and was also reduced in UKA patients compared with TKA patients (adjusted OR 0.33, 95% CI 0.16 to 0.67; p = 0.022) in multivariate analysis. The continued use of opioids after six months was 11.8% in those undergoing TKA and 8.3% in those undergoing UKA (p = 0.149). The multivariate models for second prescriptions, continued use with more than five, and continued use beyond six months yielded concordance scores of 0.70, 0.86, and 0.83, respectively. Conclusion. Compared with TKA, patients undergoing UKA are less likely to require a second opioid prescription and use significantly fewer opioid prescriptions. Thus, orthopaedic surgeons should adjust their patterns of prescription and educate patients about the reduced expected analgesic requirements after UKA compared with TKA. Cite this article: Bone Joint J 2019;101-B(7 Supple C):22–27

Purpose. The purpose was to determine if the use of cold irrigation fluid in routine knee arthroscopy leads to a reduction in post operative pain. Background. Some surgeons use cooled irrigation fluid in knee arthroscopy in the hope that it may lead to a reduction in post operative pain and swelling. There is currently no evidence for this, although there is some evidence to support the use of cold therapy post operatively in knee surgery. Methodology. We conducted a blind randomised controlled trial comparing the use of cooled (4°C) and room temperature irrigation fluid in routine arthroscopic knee surgery. Pain was recorded on a numerical scale (0 to 10) hourly for 3 hours post-operatively, at discharge and daily for 1 week. A detailed record of analgesic consumption was recorded. Patients were randomised into the cooled group (mean age 50.1 years) and the room temperature group (mean age of 46.1 years). Results. The average hourly difference in pain score for the first 3 hours post operatively was 0.12, 0.57, and 0.23 with reduced pain scores in the cooled fluid group, but this did not reach statistical significance. Total analgesic administration in theatre, recovery and the ward was lower in the cooled fluid group, as was the self administration of analgesia for the week after discharge. No increased complications where seen. Conclusion. No significant difference in patient reported pain scores has been demonstrated after the use of cooled irrigation fluid in routine knee arthroscopy. The tendency to a slight reduction in analgesic consumption in the cooled fluid group may have more significant benefits in complex arthroscopic knee surgery such as ligament reconstruction, this requires further study

Aims

Adenosine, lidocaine, and Mg²⁺ (ALM) therapy exerts differential immuno-inflammatory responses in males and females early after anterior cruciate ligament (ACL) reconstruction (ACLR). Our aim was to investigate sex-specific effects of ALM therapy on joint tissue repair and recovery 28 days after surgery.

Aims

Despite new technologies for total knee arthroplasty (TKA), approximately 20% of patients are dissatisfied. A major reason for dissatisfaction and revision surgery after TKA is persistent pain. The radiological grade of osteoarthritis (OA) preoperatively has been investigated as a predictor of the outcome after TKA, with conflicting results. The aim of this study was to determine if there is a difference in the intensity of pain 12 months after TKA in relation to the preoperative radiological grade of OA alone, and the combination of the intensity of preoperative pain and radiological grade of OA.

The postoperative analgesic effects of intra-articular injections of bupivacaine and/or morphine were examined prospectively in 437 patients who had total knee replacement for osteoarthritis. They were divided randomly into four groups. Group I received 10 mg of morphine (1 ml) and 9 ml of saline, group II received 10 ml of bupivacaine (2.5 mg/ml), group III received 10 ml of saline, and group IV received 10 mg of morphine (1 ml) and 9 ml of bupivacaine (2.5 mg/ml). All analgesics administered in the first 24 hours after operation were recorded. The patients rated their pain on the McGill-Melzack scale at 1, 6, 12 and 24 hours. No significant differences were found between any of the groups in the use of Demoral and/or Toradol in 24 hours, the length of stay in hospital or the pain rating at 1, 6, 12 or 24 hours. Patients in groups I and IV, whose injections included morphine, used significantly more morphine in the first 24 postoperative hours than did groups II or III

We have performed a prospective double-blind, randomised controlled trial over two years to evaluate the efficacy and safety of an intra-operative peri-articular injection of triamcinolone acetonide in patients undergoing medial unicondylar knee replacement. We randomised 90 patients into two equal groups. The study group received an injection of triamcinolone acetonide, bupivacaine, and epinephrine into the peri-articular tissues at the end of the operation. The control group received the same injection mixture but without the addition of triamcinolone. The peri-operative analgesic regimen was standardised. The study group reported a significant reduction in pain (p = 0.014 at 12 hours, p = 0.031 at 18 hours and p = 0.031 at 24 hours) and had a better range of movement (p = 0.023 at three months). There was no significant difference in the rate of infection and no incidence of tendon rupture in either group. The addition of corticosteroid to the peri-articular injection after unicondylar knee replacement had both immediate and short-term benefits in terms of relief from pain, and rehabilitation with no increased risk of infection

Introduction. The prescription of opioids has increased in the last two decades. Recently, several states have developed online Prescription Drug Monitoring Programs aimed at preventing overprescribing of controlled substances. Unicompartmental knee arthroplasty (UKA) has been shown to provide improved early functional outcomes, faster recovery, and less postoperative morbidity and pain than total knee arthroplasty (TKA). The aim of this study is to evaluate differences in opioid prescription requirements between patients undergoing TKA and UKA. Methods. We retrospectively reviewed consecutive series of primary TKA from January 2017 to July 2017 and primary UKA from January 2016 to July 2017 using standardized perioperative pain protocols. All patients that underwent any other procedure 6 months prior to and after index surgery were excluded, resulting in 740 TKA and 241 UKA. Demographic and comorbidity information was collected for all patients. Opioid prescriptions, morphine milligram equivalents (MME), sedatives, benzodiazepines, and stimulants were collected from State Controlled Substance Monitoring website 6 months prior and after index procedures. Univariate and multivariate analysis were performed for patients that had a second prescription and continued use (defined as more than 6 months postoperatively). Results. Patients undergoing UKA had a second opioid prescription filled 50.2% of the time compared to 60.5% for TKA (p=0.006). In addition, continued opioid use after 6 months was 8.3% in UKAs compared to 11.8% in TKAs (p=0.149). When controlling for potential confounders, patients undergoing UKA were less likely to require a second prescription than TKA patients (adjusted odds ratio: 0.603 (95% Confidence Interval (CI): 0.425–0.855). In addition, continued use of opioids after 6 months was also reduced compared to patients undergoing TKA (adjusted OR: 0.51, 95% CI: 0.27–0.97) in the multivariate analysis. Other independent predictors of continued opioid use include obesity (OR 1.79, 95% CI 1.07–3.00) and preoperative opioid use (OR 1.66 per script, 95% CI: 1.49–1.86). Our models for second script and continued use reported AUC scores of 0.65 and 0.85, respectively. Conclusion. Patients with UKA are less likely to require a second opioid prescription and have continued opioid use even when controlling for a variety of potential confounders. Given the reduced opioid requirements associated with UKA, this study supports that orthopaedic surgeons should adjust their prescription patterns and educate patients regarding expected analgesic needs. Due to the retrospective nature of this study we were unable to precisely quantify the amount of opioids consumed in these patient groups. An ongoing prospective study will more accurately determine the duration and quantity of opioid use after UKA compared to TKA

Introduction. Although we know that smoking damages health, we do not know impact of smoking on a patient's outcome following primary knee arthroplasty (KA). In the UK, clinical commissioning groups (CCGs) have the authority (& funds) to commission healthcare services for their communities. Over the past decade, an increasing number of CCGs are using smoking as a contraindication for patients with end-stage symptomatic knee arthritis being referred to a specialist for due consideration of KA without any clear evidence of the associated risks & benefits. The overall objective of this study is to compare clinical outcomes after knee arthroplasty surgery in smokers, ex-smokers & non-smokers. Methods. We obtained data from the UK Clinical Research Practice Datalink (CPRD) that contains information on over 11 million patients (7% of the UK population) registered at over 600 general practices. CPRD data was linked to Hospital Episode Statistics, hospital admissions & Patient Reported Outcome Measures (PROMs) data. We collected data on all KAs (n=64,071) performed over a 21-year period (1995 to 2016). Outcomes assessed included: local & systemic complications (at 6-months post-surgery): infections (wound, respiratory, urinary), heart attack, stroke & transient ischaemic attack, venous thromboembolism, hospital readmissions & GP visits (1-year), analgesic use (1-year), surgical revision (up to 20-years), mortality (90-days and 1-year), & 6-month change from pre-operative scores in Oxford Knee Score (OKS). Regression modelling is used to describe the association of smoking on outcomes, adjusting for confounding factors. Results. Smoking was associated with an increased risk of lower respiratory tract infections (LRTI) (4.2% smokers vs. 2.7% non-smokers) (Odds Ratio (OR) 0.76, p-value 0.017). LRTI were similar in ex-smokers & smokers at 3.9%. There was no association with any of the other 6-month complications. Pain medication use over 1-year post surgery was higher in smokers compared to non-smokers: gabapentinoids 7.4% vs. 5.2% (OR 0.74, p< 0.001), opioids 45.9% vs. 35.3% (OR 0.79, p< 0.001), NSAIDs 51.6% vs. 46.1% (OR 0.91, p = 0.044). Mortality was higher in smokers at 1-year compared to non-smokers (hazard ratio (HR) 0.53, p<0.001) & ex-smokers (HR 0.65, p = 0.037), but there was no difference observed at 90-days. There was no association of smoking on revision surgery over 20-years follow up. Smoking was associated with worse postoperative OKS being 3.1 points higher in non-smokers (p<0.001) & 3.0 points higher in ex-smokers (p<0.001). The overall change in OKS before & after surgery was 13.9 points in smokers versus 16.3 points in non-smokers (p<0.001) & 15.7 points in ex-smokers (p<0.001). Over the year following surgery, smokers were more likely to visit their GP, but there was no association with hospital readmission rates. Conclusion. This is the largest study with linked primary care & secondary care data highlighting impact of a preventable patient factor on outcome of a routinely performed planned intervention. Smokers achieved clinical meaningful improvements in patient reported pain & function (OKS) following KA, although their attained post-operative OKS was lower than in non-smokers & ex-smokers. Levels of pain medication use were notably higher in both smokers & ex-smokers. As smokers achieved good clinical outcomes following KA surgery, smoking should not be a barrier to referral for or consideration of KA. However, the study does highlight particular risks a patient is taking if he/she continues to smoke when being considered for elective knee arthroplasty. This study will help the family physicians as well as patients to make an informed decision on whether to go ahead with a planned intervention whilst patient continues to be an active smoker or not. Key Words: Knee Arthroplasty, Smoking, Patient Reported Outcomes, Epidemiology, Complications

Aims

This study compared the cobalt and chromium serum ion concentration of patients treated with two different metal-on-metal (MoM) hinged total knee arthroplasty (TKA) systems, as well as a titanium nitride (TiN)-coated variant.