Obese Patients Achieve Good Improvements in Patient-Reported Outcome Measures After Medial Unicompartmental Knee Arthroplasty Despite a Lower Preoperative Score.

BACKGROUND: In this study, we examined the association between obesity and patient-reported outcome measures after medial unicompartmental knee arthroplasty (MUKA), assessed through score changes, Patient Acceptable Symptom State (PASS), and minimal important change (MIC). Second, the association between obesity and early readmissions was examined. METHODS: A total of 450 MUKAs (mean body mass index [BMI] 30.3, range, 19.6-53.1), performed from February 2016 to December 2020, were grouped using BMI: <30, 30-34.9, and >34.9. Oxford Knee Score (OKS), Forgotten Joint Score (FJS), and Activity and Participation Questionnaire (APQ) were assessed preoperatively and at 3, 12, and 24 months, postoperatively. The 12-month PASS and MIC were also assessed, defining PASS as OKS = 30, MIC-OKS as change in OKS = 8, and MIC-FJS as change in FJS = 14. RESULTS: No significant differences in OKS change were found between BMI groups. After 12 months, patients who had a BMI of 30-34.9 had lower change in FJS (estimate -8.1, 95% CI -14.9 to -1.4) and were less likely to reach PASS (odds ratio 0.4, 95% CI 0.2-0.7) as well as MIC-FJS (odds ratio 0.5, 95% CI 0.2-0.9). Both obese groups had lower change in APQ after 12 months. Differences in 90-day readmission rates were nonsignificant between groups. CONCLUSION: Our findings of no differences in OKS improvement between BMI groups and achieving MIC for BMI > 34.9 suggest good improvements in obese patients despite lower preoperative scores, supporting contemporary indications for MUKA. Lower APQ development and achievement of 12-month PASS may be used when addressing expectations of recovery.

Consequences for preoperative pain and function when postponing elective knee and hip arthroplasty.

INTRODUCTION: The coronavirus outbreak causes postponement of elective surgery. We evaluated how pain, function and general health were impacted by postponing elective knee and hip arthroplasty in patients with knee and hip osteoarthritis with no known surgery rescheduling date due to the coronavirus outbreak. METHODS: This study included 194 patients from a Danish public hospital with postponed elective primary knee or hip arthroplasty due to the lockdown. Patients responded to questionnaires when their surgery was cancelled and before surgery. Changes in pain and function were evaluated with the Oxford Knee and Hip Scores (OKS, OHS) and their general health with the EuroQol 5-dimension scale (EQ5D). Additionally, we asked about the patients' concerns and whether they felt improved, unchanged or deteriorated during the waiting period. RESULTS: Complete data were obtained for 110 (57%) patients, 59 and 51 awaiting knee or hip arthroplasty (median age 71 years, 62% were female), respectively. Arthroplasty was postponed for a median (range) 98 (63-161) days. A total of 34% were concerned that the postponement would lead to a poorer outcome. Mean OKS and OHS differences were 0 (95% confidence interval (CI): -1-1) and -1 (95% CI: -2-0) from surgery cancellation to re-scheduled surgery. The mean EQ5D index difference was 0.0 (95% CI: 0.0-0.1) for both groups. A total of 75 (68%) patients felt an important deterioration of their condition. CONCLUSIONS: Pre-operatively, patients worried about experiencing an altered treatment outcome due to postponed surgery and felt that their condition had deteriorated during the waiting period although this was not reflected in patient-reported outcome measures. FUNDING: Department of Orthopaedic Surgery. TRIAL REGISTRATION: not relevant.

Population pharmacokinetics of ropivacaine used for local infiltration anaesthesia during primary total unilateral and simultaneous bilateral knee arthroplasty.

BACKGROUND: Ropivacaine is commonly used in local infiltration anaesthesia (LIA) as pain management after total knee arthroplasty (TKA). Although considered safe, no studies evaluated the pharmacokinetics of high-dose ropivacaine infiltration in simultaneous bilateral TKA. METHODS: We studied 13 patients undergoing unilateral and 15 undergoing bilateral TKA. Standard LIA technique was used with ropivacaine 0.2%, 200 ml (400 mg) injected peri-articularly in each knee. Free and total plasma concentrations of ropivacaine were measured within 24 h using liquid chromatography-mass spectrometry. A population pharmacokinetic model was built using non-linear mixed-effects models. RESULTS: Peak free ropivacaine concentration was 0.030 (0.017-0.071) µg ml-1 (mean [99% confidence interval]) vs 0.095 (0.047-0.208) µg ml-1, and peak total ropivacaine concentration was 0.756 (0.065-1.222) µg ml-1vs 1.695 (0.077-3.005) µg ml-1 for unilateral and bilateral TKA, respectively. The pharmacokinetics was ascribed a one-compartment model with first-order absorption. The main identified covariates were protein binding, allometrically scaled body weight on clearance and volume, and unilateral or bilateral surgery on volume. CONCLUSIONS: This is the first study to investigate the pharmacokinetics of free and total ropivacaine after unilateral and bilateral TKA. A population model was successfully built and peak free ropivacaine concentration stayed below previously proposed toxic thresholds in patients undergoing unilateral and bilateral TKA receiving LIA with high-dose ropivacaine. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04702282.

Introduction of a New Treatment Algorithm Reduces the Number of Periprosthetic Femoral Fractures After Primary Total Hip Arthroplasty in Elderly Females.

BACKGROUND: Increasing global usage of cementless prostheses in total hip arthroplasty (THA) presents a challenge, especially for elderly patients. To reduce the risk of early periprosthetic femoral fractures (PFFs), a new treatment algorithm for females older than 60 years undergoing primary THA was introduced. The aim of this study was to determine the impact of the new treatment algorithm on the early risk of perioperative and postoperative PFFs and guideline compliance. METHODS: A total of 2405 consecutive THAs that underwent primary unilateral THA at our institution were retrospectively identified in the period January 1, 2013-December 31, 2018. A new treatment algorithm was introduced on April 1, 2017 with female patients aged older than 60 years intended to receive cemented femoral components. Before this, all patients were scheduled to receive cementless femoral components. Demographic data, number of perioperative and postoperative PFFs, and surgical compliance were recorded, analyzed, and intergroup differences compared. RESULTS: The utilization of cemented components in female patients older than 60 years increased from 12.3% (n = 102) to 82.5% (n = 264). In females older than 60 years, a significant reduction in the risk in early postoperative and intraoperative PFF after introduction of the new treatment algorithm was seen (4.57% vs 1.25%; P = .007 and 2.29% vs 0.31%; P = .02, respectively). Overall risk for postoperative and intraoperative fractures combined was also reduced in the entire cohort (4.1% vs 2.0%; P = .01). CONCLUSION: Use of cemented fixation of the femoral component in female patients older than 60 years significantly reduces the number of PFFs. Our findings support use of cemented femoral fixation in elderly female patients.

Regional differences between the US, Scandinavia, and South Korea in patient demographics and patient-reported outcomes for primary total knee arthroplasty.

INTRODUCTION: Differences in total knee arthroplasty (TKA) patient demographics and clinical outcomes may exist between international regions, yet research is limited. The aim of this study was, therefore, to compare TKA patient demographics and patient-reported outcome measure (PROM) scores between the US, Scandinavia, and South Korea. MATERIALS AND METHODS: A total of 398 TKA patients from three regions were assessed: 169 in Scandinavia (3 centers), 129 in the US (3 centers), and 100 patients in South Korea (2 centers). Regional variation in patient demographics was assessed using Kruskal-Wallis H tests. Regional variation in PROM scores from preoperative, 1-, 3- and 5-year visits was assessed using piecewise linear mixed effect models. The PROMs analyzed were a numerical rating scale for satisfaction and the Knee Osteoarthritis Outcome Score. RESULTS: South Korean patients were the oldest (p < 0.001) and had the highest Charnley class (p < 0.001); US patients had the highest BMI (p < 0.001); Scandinavian patients had the lowest preoperative KL grade (p < 0.001). Scandinavian patients were associated with better preoperative and worse postoperative PROM scores. Scandinavian patients were also associated with moderately lower levels of satisfaction. These differences were lessened but remained significant after controlling for relevant demographic and surgical factors. CONCLUSIONS: Regional differences were found in TKA patient demographics and PROMs between the US, Scandinavia, and South Korea. The regional differences in patient demographics support the need for more research and clear guidelines related to TKA appropriateness criteria. The better preoperative and worse postoperative Scandinavian PROM scores may have been related to their less severe KL grade but might also reflect cultural differences in how patients reflect on their health state when answering PROMs. Clinicians should be aware of these international differences in PROM scores when interpreting studies conducted in different international regions. Future studies should investigate TKA variation between more international regions and assess intraregional variation. LEVEL OF EVIDENCE: Level III.

Patient Acceptable Symptom State at 1 and 3 Years After Total Knee Arthroplasty: Thresholds for the Knee Injury and Osteoarthritis Outcome Score (KOOS).

BACKGROUND: To facilitate the interpretation of numerical patient-reported outcome measure (PROM) scales, concepts such as the patient acceptable symptom state (PASS) have been introduced. Currently, no PASS thresholds have been established for the Knee injury and Osteoarthritis Outcome Score (KOOS) after total knee arthroplasty. The aims of the current study were to define PASS thresholds for the KOOS subscales and several other generic and knee-specific PROMs at 1 and 3 years after total knee arthroplasty using data from an international, multicenter clinical outcome study of a modern, well-performing implant system. METHODS: The study cohort consisted of 499 patients undergoing total knee arthroplasty from an international, multicenter study. At 1 and 3 years after a total knee arthroplasty, patients completed the KOOS, EuroQoL 5-dimension 3-level (EQ-5D-3L), EuroQol visual analog scale (EQ-VAS), and numerical rating scales (NRS) for knee-related pain and satisfaction. PASS thresholds were calculated at each follow-up interval using 3 anchor-based approaches, using patient-reported satisfaction as the anchor. RESULTS: According to our satisfaction anchor, 302 (78.9%) of 383 responding patients were satisfied at 1 year, and 242 (80.4%) of 301 responding patients were satisfied at 3 years. PASS thresholds were 84.5 points at 1 year and 87.5 points at 3 years for KOOS pain, 80.5 points at 1 year and 84.0 points at 3 years for KOOS symptoms, 83.0 points at 1 year and 87.5 points at 3 years for KOOS activities of daily living, 66.0 points at 1 year and 66.0 points at 3 years for KOOS quality of life, 83.0 points at 1 year and 90.5 points at 3 years for EQ-VAS, 0.80 point at 1 year and 0.80 point at 3 years for EQ-5D, and 1.8 points at 1 year and 1.8 points at 3 years for NRS pain. CONCLUSIONS: The current study is the first, to our knowledge, to propose PASS thresholds for the KOOS subscales at 1 and 3 years after total knee arthroplasty and contributes to PASS literature on other common PROMs. These findings will provide a useful reference for future total knee arthroplasty outcome studies and will help to determine what patients consider to be satisfactory operations. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Promising early outcomes of a novel anatomic knee system.

PURPOSE: The primary aim of this study was to report the early clinical and radiographic outcomes of patients who have been treated with total knee arthroplasty (TKA) using the Persona knee system. The secondary aim was to compare patient-reported outcomes (PROs) of the Persona knee system to those of the NexGen implant. METHODS: A registry-based study of a consecutive series of 112 patients (129 knees) treated with the Persona knee system from a single center was conducted. Preoperative, 1-year, and 2-year radiographs and PROs were analyzed. Postoperative radiographs were assessed for radiolucency and component positioning. Patients were monitored for postoperative complications and revision. Two-year PROs were compared to a 1:1 propensity score-matched cohort of patients treated with the NexGen knee system. RESULTS: Ninety-five percent of knees were within literature-defined safe ranges of the anatomical tibiofemoral axis, tibial varus/valgus angle, femoral flexion/extension angle, and tibial slope. Radiolucency was observed in 0.9% and 1.3% of knees at one and 2 years, respectively. Two-year PRO values demonstrated clinically meaningful improvements from the preoperative values. The cumulative 2-year percent revision was 3.0% (95% confidence interval 1.9-3.8%); there were no revisions due to implant mechanical failure. Patients treated with the Persona knee system had higher KOOS symptom (p = 0.037) and KOOS QOL (p < 0.001) scores compared to patients with the NexGen knee system. CONCLUSIONS: This knee design demonstrates excellent clinical outcomes, similar or better than the NexGen knee system, at early follow-up. LEVEL OF EVIDENCE: III.

Medial Overhang of the Tibial Component Is Associated With Higher Risk of Inferior Knee Injury and Osteoarthritis Outcome Score Pain After Knee Replacement.

BACKGROUND: The aim of this prospective multicenter study is to investigate the association among (1) tibial site-specific overhang of medial, anterior, and lateral overhang in relation to Knee Injury and Osteoarthritis Outcome Score pain 1 year after surgery (1 Y KOOS pain) and (2) the malalignment of TKA components including overall malalignment in relation to 1 Y KOOS pain. METHODS: From 10 centers, across 4 continents, 323 patients were enrolled from October 2011 to February 2014. Radiographs were analyzed for tibial overhang on medial, anterior, and lateral site and for overall, tibial, femur, and combined malalignment. A 1 Y KOOS pain score <70 represented an unsatisfactory pain level. RESULTS: A significant association was observed between medial overhang and 1 Y KOOS pain with a cut-off of <70 (P = .04), with an odds ratio of 0.46. No significant associations were observed among the independent variables of lateral and anterior overhang or for overall, tibial, femoral, and combined component malalignment, and the dependent variable of 1 Y KOOS pain <70. CONCLUSION: This prospective multicenter study showed a significant association between medial overhang of the tibial component and a 1 Y KOOS pain <70. The related odds ratio was 0.46, which demonstrates that medial overhang may lead to a 54% reduced chance for entering an acceptable pain category 1 year after surgery when receiving a TKA.

Low Risk of Thromboembolic Events After Routine Administration of Tranexamic Acid in Hip and Knee Arthroplasty.

BACKGROUND: The blood-conserving effect of intravenous (IV) tranexamic acid (TXA) is well-documented for total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, the risk of thromboembolic (TE) events after routine use of TXA is unclear and the safety profile is debated. This retrospective study investigates patient characteristics, occurrences, and predictors of TE events after routine administration of IV TXA in THA and TKA. METHODS: Three thousand one hundred fifty-nine THA or TKA procedures performed from 2007-2013 at our institution were included. IV TXA, 1 g, was administered preoperatively if not contraindicated. Relevant patient characteristics and comorbidity information were extracted locally from the database. Data on TE events occurring within 90 days postoperatively came from The Danish National Patient Registry. Patient characteristics, comorbidities, and TE events were compared between TXA groups. A logistic regression model was used to evaluate predictors of TE events. RESULTS: Of 3159 procedures, 2766 (87.6%) received TXA (TXA+ group) preoperatively, whereas 393 (12.4%) did not (TXA- group). Mean age, distributions of gender, American Society of Anesthesiologists score, anesthesia method, duration of surgery, diagnosis, and survival status were all statistically significant different (P values <.05) between TXA groups. The studied comorbidities were all significantly different (TXA+ vs TXA- group; P values ≤.002). We found 31 (1.0%) TE events out of 3159 procedures, with no significant group difference in TE events (TXA+: 27 out of 2766 = 1.0%, TXA-: 4 out of 393 = 1.0%, P value = .55 for any event). For the TXA+ group, 0.5% suffered from deep venous thrombosis, 0.3% from acute myocardial infarction, and 0.2% from a pulmonary embolism. In the TXA+ group, higher age (odds ratio [OR] = 1.06, 95% confidence interval = 1.02-1.11, P = .005) and present cardiovascular disease (OR = 4.78, 95% confidence interval = 1.72-13.28, P = .003) were associated with an increased risk of TE events. CONCLUSION: The findings suggest that routine use of IV TXA for TKA and THA as safe with low occurrence of TE events, although a large prospective trial should confirm this.