Primary Unicompartmental Knee Arthroplasty Research Articles

Previous arthroscopy does not decrease survivorship or functional outcomes for unicompartmental knee arthroplasty patients.

Arthroscopic procedures for osteoarthritis (OA), in particular arthroscopic meniscectomy, have poorer long-term clinical outcomes compared to those managed non-operatively. In addition, previous arthroscopy is associated with worse outcomes following subsequent total knee arthroplasty (TKA), however there is limited data on the impact on subsequent unicompartmental knee arthroplasty (UKA) outcomes. The aim of the study is to investigate whether patients who had arthroscopy prior to UKA have differences in survivorship or functional outcomes compared to those with no prior arthroscopy. All patients who received either a primary medial or lateral UKA at four large tertiary hospitals were included (n = 2,272). Patient data (age, sex, ethnicity, body mass index (BMI), American Society of Anesthesiologists (ASA) status and surgical data) was recorded following systematic review of all clinical notes and radiographs. Differences between survival curves were analysed using log-rank curves. Differences between categorical data was compared using Fisher's exact or Chi-squared tests, and differences between continuous variables were compared using t-tests. There was no difference between the survival curves for UKA patients with previous arthroscopy compared to those with no previous arthroscopy (10 years: 91% UKA with previous arthroscopy vs. 92% no previous arthroscopy; 15 years: 78% previous arthroscopy vs. 86% no previous arthroscopy; p = 0.50). Oxford Knee Score (OKS) was comparable between patients who had previous arthroscopy and those who had no previous arthroscopy at 6 months (38.8 vs. 39.3, p = 0.45), 5 years (42.0 vs. 40.4, p = 0.11) and 10 years (40.8 vs. 40.2, p = 0.71). In this large patient cohort with comprehensive review of clinical data and outcomes, we found that prior arthroscopy did not affect survivorship or functional outcomes of UKA patients.

Accuracy and completeness of registry-reported unicompartmental knee arthroplasty revision.

The key outcome of joint registries is revision events, which inform clinical practice and identify poor-performing implants. Registries record revision events and reasons, but accuracy may be limited by a lack of standardized definitions of revision. Our study aims to assess the accuracy and completeness of unicompartmental knee arthroplasty (UKA) revision and indications reported to the New Zealand Joint Registry (NZJR) with independent clinical review. Case record review of 2272 patients undergoing primary UKA at four large tertiary hospitals between 2000 and 2017 was performed, identifying 158 patients who underwent revision. Detailed review of clinical findings, radiographs and operative data was performed to identify revision cases and the reasons for revision using a standardized protocol. These were compared to NZJR data using chi-squared and Fisher exact tests. The NZJR recorded 150 (95%) of all UKA revisions. Osteoarthritis progression was the most common reason on the systematic clinical review (35%), however, this was underreported to the registry (8%, P < 0.001). A larger proportion of revisions reported to the registry were for 'pain' (30% of cases vs. 5% on clinical review, P < 0.001). A reason for revision was not reported to the registry for 10% of cases. The NZJR had good capture of UKA revisions, but had significant differences in registry-reported revision reasons compared to our independent systematic clinical review. These included over-reporting of 'pain', under-reporting of osteoarthritis progression, and failing to identify a revision reason. Efforts to improve registry capture of revision reasons for UKA could be addressed through more standardized definitions of revision and tailored revision options for UKA on registry forms.

ACCURACY OF REGISTRY-REPORTED REASONS FOR UNICOMPARTMENTAL KNEE ARTHROPLASTY REVISION

IntroductionA key outcome measured by national joint registries are revision events. This informs best practice and identifies poor-performing surgical devices. Although registry data often record reasons for revision arthroplasty, interpretation is limited by lack of standardised definitions of revision reasons and objective assessment of radiologic and laboratory parameters. Our study aim was to compare reasons for unicompartmental knee arthroplasty (UKA) revision reported to the New Zealand Joint Registry (NZJR) with reasons identified by independent clinical review.MethodsA total of 2,272 patients undergoing primary medial and lateral UKA at four large tertiary hospitals between 2000 and 2017 were included. A total of 158 patients underwent subsequent revision with mean follow-up of 8 years. A systematic review of clinical findings, radiographs and operative data was performed to identify revision cases and to determine the reasons for revision using a standardised protocol. These were compared to reasons reported to the NZJR using Chi-squared and Fisher exact tests.ResultsOsteoarthritis progression was the most common reason for revision on systematic clinical review (30%), however this was underreported to the registry (4%, p&lt;0.001). A larger proportion of revisions reported to the registry were for ‘unexplained pain’ (30% of cases vs. 4% on clinical review, p&lt;0.001). A reason for revision was not reported to the registry for 24 (15%) of cases.Discussion and ConclusionWe found significant inaccuracies in registry-reported reasons for revision following UKA. These included over-reporting of ‘unexplained pain’, under-reporting of osteoarthritis progression, and failure to identify a reason for revision. Efforts to improve registry capture of revision reasons for UKA should focus on increasing accuracy in these three areas. This could be addressed through standardised recording methods and tailored revision reason options for UKA for surgeons to select when recording the reasons.

Postoperative orthostatic intolerance following fast-track unicompartmental knee arthroplasty: incidence and hemodynamics—a prospective observational cohort study

BackgroundEarly postoperative mobilization is essential for early functional recovery but can be inhibited by postoperative orthostatic intolerance (OI). Postoperative OI is common after major surgery, such as total knee arthroplasty (TKA). However, limited data are available after less extensive surgery, such as unicompartmental knee arthroplasty (UKA). We, therefore, investigated the incidence of OI as well as cardiovascular and tissue oxygenation responses during early mobilization after UKA.MethodsThis prospective single-centre observational study included 32 patients undergoing primary UKA. Incidence of OI and cardiovascular and tissue oxygenation responses during mobilization were evaluated preoperatively, at 6 and 24 h after surgery. Perioperative fluid balance, bleeding, surgery duration, postoperative hemoglobin, pain during mobilization and opioid usage were recorded.ResultsDuring mobilization at 6 h after surgery, 4 (14%, 95%CI 4–33%) patients experienced OI; however, no patients terminated the mobilization procedure prematurely. Dizziness and feeling of heat were the most common symptoms. OI was associated with attenuated systolic and mean arterial blood pressure responses in the sitting position (all p < 0.05). At 24 h after surgery, 24 (75%) patients had already been discharged, including three of the four patients with early OI. Only five patients were available for measurements, two of whom experienced OI; one terminated the mobilization procedure due to intolerable symptoms. We observed no statistically significant differences in perioperative fluid balance, bleeding, surgery duration, postoperative hemoglobin, pain, or opioid usage between orthostatic intolerant and tolerant patients.ConclusionsThe incidence of orthostatic intolerance after fast-track unicompartmental knee arthroplasty is low (~ 15%) and is associated with decreased orthostatic pressure responses. Compared to the previously described orthostatic intolerance incidence of ~ 40% following total knee arthroplasty, early orthostatic intolerance is uncommon after unicompartmental knee arthroplasty, suggesting a procedure-specific component.Trial registration: Prospectively registered at ClinicalTrials.gov; registration number: NCT04195360, registration date: 13.12.2019.

Epidemiology and prognostic factors for new-onset deep venous thrombosis after unicompartmental knee arthroplasty: a retrospective study

BackgroundPatients who underwent knee joint arthroplasty were at risk of venous thromboembolic events (VTEs), however, less studies were conducted to demonstrate the epidemiology and risk factors of deep venous thrombosis (DVT) following unicompartmental knee arthroplasty (UKA). Objective of this study was to explore the incidence and prognostic factors of DVT after UKA.MethodsPatients who underwent primary UKA from December 2018 to June 2022 were recruited in this study. Demographic characteristics, operation related variables and laboratory index were extracted and analyzed. Receiver operating characteristic analysis was performed to detect the optimum cut-off value for variables of interest. Univariate and multivariate logistic analysis were performed to identify risk factors of DVT.Results351 UKAs with a mean age of 65.4 ± 7.1 years were reviewed. After 12.9 ± 11.2 months follow-up, 35 DVTs were confirmed which indicating an incidence of 9.9%. The results showed that occupation (agricultural laborer) (P = 0.008), disease duration > 8.5 years (P = 0.035), operation time > 169 min (P = 0.003), intraoperative blood loss > 102 ml (P < 0.001), BMI > 26.8 kg/m 2 (P = 0.001), preoperative D-dimer > 0.29 mg/L (P = 0.001), prothrombin time < 10.7 s (P = 0.033) and INR < 0.98 (P = 0.032) between DVT and Non-DVT group were significantly different. Multivariate logistic regression analysis showed intraoperative blood loss > 102 ml (OR, 3.707; P, 0.001), BMI > 26.8 kg/m 2 (OR, 4.664; P, 0.004) and D-dimer > 0.29 mg/L (OR, 2.882; P, 0.009) were independent risk factors of DVT after UKA.ConclusionThe incidence of DVT in the present study was 9.9%, extensive intraoperative blood loss, advanced BMI and high level of D-dimer would increase the risk of lower extremity thrombosis by 2–4 times.

Functional outcomes and return to sports, work, and daily activities after revision UKA compared to primary UKA and TKA

Unicompartmental knee arthroplasty (UKA), in addition to total knee arthroplasty (TKA), has been shown to be effective in the surgical treatment of knee osteoarthritis with appropriate patient selection. In clinical studies, it has demonstrated superior functional results with lower complication rates. In clinical practice, these advantages must be weighed against the disadvantage of an increased revision rate, especially in younger patients with sports and work activities. The aim of this study was to compare the functional outcome as well as the time to return to daily activities, work, and sports after revision of UKA to TKA with those of primary UKA and primary TKA using amatched-pair analysis. The study was based on amatched-pair analysis at two defined time points, always comparing 28patients who underwent either revision of aUKA to aTKA, primary UKA, or primary TKA. Patients completed the Oxford Knee Score, UCLA score, Knee Society score, and WOMAC score during standardized follow-up. In addition, postoperative patient satisfaction and return to activities of daily living, work, and sports were recorded in astandardized manner, and aclinical examination was performed. The four functional scores studied showed acommon trend in favor of UKA, followed by primary TKA and revision TKA. The differences between converted UKA and primary TKA were not significant. However, at 3.2years after the last surgery, the results of the converted UKA were significantly lower than those of the primary UKA. Return to work and sports tended to occur the earliest after UKA, followed by TKA and the revision group. All groups showed atendency to engage in low-impact sports. The functional results of revised UKA were significantly inferior to those of primary UKA based on a3-year follow-up. Return to work, sports, and activities of daily living tended to take longer after revision than after primary implantation of either aUKA or aTKA.

The Deep-MCL Line: A Reliable Anatomical Landmark to Optimize the Tibial Cut in UKA.

The extramedullary guides for the tibial resection during medial unicompartmental knee arthroplasty (UKA) are inaccurate, with an error risk in coronal and sagittal planes and cut thickness. It was our hypothesis that the use of anatomical landmarks for the tibial cut can help the surgeon to improve accuracy. The technique described in this paper is based on the use of a simple and reproducible anatomical landmark. This landmark is the line of insertion of the fibers of the deep medial collateral ligament (MCL) around the anterior half of the medial tibial plateau called the "Deep MCL insertion line". The used anatomical landmark determines the orientation (in the coronal and sagittal planes) and the thickness of the tibial cut. This landmark corresponds to the line of insertion of the fibers of the deep MCL around the anterior half of the medial tibial plateau. A consecutive series of patients who underwent primary medial UKA between 2019 and 2021 were retrospectively reviewed. A total of 50 UKA were included. The mean age at the time of surgery was 54.5 ± 6.6 years (44-79). The radiographic measurements showed very good to excellent intra-observer and inter-observer agreements. The limb and implant alignments and the tibial positioning were satisfying, with a low rate of outliers and good restoration of the native anatomy. The landmark of the insertion of deep MCL constitutes a reliable and reproducible reference for the tibial cut axis and thickness during medial UKA, independent of the wear severity.

10-year evolution of day-case hip and knee arthroplasty: a Danish nationwide register study of 166,833 procedures from 2010 to 2020

No previous studies have investigated the use of day-case arthroplasty in Denmark on a national scale. We investigated the frequency of day-case surgery in total hip (THA), total knee (TKA), and unicompartmental knee arthroplasty (UKA) from 2010 to 2020 in Denmark. Primary unilateral THAs, TKAs, and UKAs performed for osteoarthritis were identified in the Danish National Patient Register using procedural and diagnosis codes. Day-case surgery was defined as discharge on the day of surgery. 90-day readmissions were defined as any overnight admissions following discharge. From 2010 to 2020 Danish surgical centers performed 86,070 THAs, 70,323 TKAs, and 10,440 UKAs. From 2010 to 2014, less than 0.5% of THAs and TKAs were day-case procedures. They increased to 5.4% (95% confidence interval [CI] 4.9-5.8) of THAs and 2.8% (CI 2.4-3.2) of TKAs in 2019. From 2010 to 2014, 11% of UKAs were day-case procedures, but they increased to 20% (CI 18-22) in 2019. This increase was driven by a few surgical centers (3-7 centers). In 2010, readmission rates within 90 days of surgery were 10% after THAs and 11% after TKAs, and 9.4% for both THAs and TKAs in 2019. Readmission rates after UKA fluctuated between 4% and 7%. From 2010 to 2020 the use of day-case surgery in THA, TKA, and UKA increased in Denmark, driven by only a few centers. During the same period readmissions did not increase.

ROBOTIC ARM-ASSISTED SYSTEM FOR UNICOMPARTMENTAL KNEE ARTHROPLASTY IS ASSOCIATED WITH A LEARNING CURVE OF 11 CASES AND INCREASED OPERATING TIME

Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty, particularly for low volume surgeons. The recent introduction of robotic-arm assisted systems has allowed for increased accuracy, however new systems typically have learning curves. The objective of this study was to determine the learning curve of a robotic-arm assisted system for UKA.Methods A total of 152 consecutive robotic-arm assisted primary medial UKA were performed by five surgeons between 2017 and 2021. Operative times, implant positioning, reoperations and patient-reported outcome measures (PROMS; Oxford Knee Score, EuroQol-5D, and Forgotten Joint Score) were recorded.There was a learning curve of 11 cases with the system that was associated with increased operative time (13 minutes, p&lt;0.01) and improved insert sizing over time (p=0.03). There was no difference in implant survival (98.2%) between learning and proficiency phases (p = 0.15), and no difference in survivorship between ‘high’ and ‘low’ usage surgeons (p = 0.23) at 36 months. There were no differences in PROMS related to the learning curve. This suggested that the learning curve did not lead to early adverse effects in this patient cohort.The introduction of a robotic-arm assisted UKA system led to learning curves for operative time and implant sizing, but there was no effect on patient outcomes at early follow- up. The short learning curve was independent of UKA usage and indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons.

Similar Survivorship but Different Revision Reasons for Uncemented Mobile-Bearing and Cemented Fixed-Bearing Medial UKA: A Long-Term Population-Based Cohort Study of 2,015 Patients.

Long-term survivorship and accurate characterization of revision reasons in unicompartmental knee arthroplasty (UKA) are limited by a lack of long-term data and standardized definitions of revision. The aim of this study was to identify survivorship, risk factors, and reasons for revision in a large cohort of medial UKAs with long-term follow-up (up to 20 years). Patient, implant, and revision details for 2,015 primary medial UKAs (mean follow-up, 8 years) were recorded following systematic clinical and radiographic review. Survivorship and risk of revision were analyzed using Cox proportional hazards. Reasons for revision were analyzed using competing-risk analysis. Implant survivorship at 15 years was 92% for cemented fixed-bearing (cemFB), 91% for uncemented mobile-bearing (uncemMB), and 80% for cemented mobile-bearing (cemMB) UKAs (p = 0.02). When compared with cemFB, the risk of revision was higher for cemMB implants (hazard ratio [HR] = 1.9, 95% confidence interval [CI] = 1.1 to 3.2; p = 0.03). At 15 years, cemented implants had a higher cumulative frequency of revision due to aseptic loosening (3% to 4%, versus 0.4% for uncemented; p < 0.01), cemMB implants had a higher cumulative frequency of revision due to osteoarthritis progression (9% versus 2% to 3% for cemFB/uncemMB; p < 0.05), and uncemMB implants had a higher cumulative frequency of revision due to bearing dislocation (4% versus 2% for cemMB; p = 0.02). Compared with the oldest patients (≥70 years), younger patients had a higher risk of revision (<60 years: HR = 1.9, 95% CI = 1.2 to 3.0; 60 to 69 years: HR = 1.6, 95% CI = 1.0 to 2.4; p < 0.05 for both). At 15 years, there was a higher cumulative frequency of revision for aseptic loosening in these younger groups (3.2% and 3.5% versus 2.7% for ≥70 years; p < 0.05). Implant design and patient age were risk factors for revision of medial UKA. The findings from this study suggest that surgeons should consider using cemFB or uncemMB designs because of their superior long-term implant survivorship compared with cemMB designs. Additionally, for younger patients (<70 years), uncemMB designs had a lower risk of aseptic loosening than cemFB designs at the expense of a risk of bearing dislocation. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Payor Type is Associated With Increased Rates of Reoperation and Health-care Utilization Following Unicompartmental Knee Arthroplasty: A National Database Study.

Unicompartmental knee arthroplasty (UKA) is a common orthopedic procedure with overall good clinical outcomes; however, more recent literature has identified disparities in treatment access and outcomes based on sociodemographic factors. There is a paucity of literature examining whether payor type, including Medicare, Medicaid, and commercial insurance types, impacts early medical complications and rates of reoperation following a UKA. Patients with Medicare, Medicaid, or commercial payor type who underwent primary medial or lateral UKA between 2010 and 2019 were identified using a large national database. Ninety-day incidence of emergency department visit and 1-year incidence of revision, revision to arthroplasty, reimbursement, and cost of care were evaluated. Propensity score matching was used to control for patient demographic factors and comorbidities as covariates. Medicaid insurance was associated with an increased risk of emergency room visit (odds ratio [OR] 2.77; P < .001), revision surgery (OR 1.85; P < .001), and conversion to total knee arthroplasty (OR 1.50; P= .0292) compared to commercially insured patients. Medicaid insurance was associated with an increased risk of emergency room visit (OR 3.58; P < .001), revision surgery (OR 1.97; P < .001), and conversion to total knee arthroplasty (OR 1.80; P= .003). Medicaid patients were associated with a higher overall cost of care and lower reimbursement than commercial and Medicare patients (P < .001 and P < .001, respectively). These findings demonstrate that payor type is associated with increased rates of reoperation and health-care utilization following UKA despite controlling for covariates. Additional work is required to understand the complex relationship between socioeconomic status and outcomes to ensure appropriate health-care access for all patients and pursue appropriate risk stratification. III, retrospective chart review.

THE LIFETIME REVISION RISK OF KNEE ARTHROPLASTY

Source of the study: University of Auckland, Auckland, New Zealand and University of Otago, Christchurch, New ZealandOutcomes following knee arthroplasty are typically defined as implant survivorship at defined timepoints, or revision incidence over time. These estimates are difficult to conceptualise, and lack context for younger patients with more remaining years of life. We therefore aimed to determine a ‘lifetime’ risk of revision as a more useful metric for total (TKA) and unicompartmental knee arthroplasty (UKA).The New Zealand Joint Registry was used to identify 96,497 primary TKAs and 13,481 primary UKAs performed between 1999 and 2019. Patient mortality and revision incidence were also extracted. Estimates of lifetime risk were calculated using an actuarial lifetable method. The estimates were stratified by age and gender. Reasons for revision were categorised using previously published standardised definitions.The lifetime risk of UKA revision was two-fold higher than TKA across all age groups (range 3.7-40.4% UKA, 1.6-22.4% TKA). Revision risk was higher for males with TKA (range 3.4%-25.2% males, 1.1%-20% females), but higher for females with UKA (range 4.3%-43.4% vs. 2.9%-37.4% for males). Revision due to infections were higher for TKA (1.5% males, 0.7% females) compared with UKA (0.4% males, 0.1% females). The increased risk in younger UKA patients was associated with higher incidence of aseptic loosening (UKA 2%, TKA 1%) and ‘unexplained pain’ (UKA 2%, TKA 0.2%).The risk for UKA was two-fold higher than TKA, and this was partially explained by a higher proportion of revisions due to ‘unexplained pain’. For TKA, males had higher risk of revision, in contrast to UKA where females had higher risk; this gender difference was associated with higher incidence of infections with TKA. Younger age, gender and higher ASA status were also associated with increased lifetime risk of UKA revision. Lifetime risk of revision can provide a meaningful measure of arthroplasty outcomes to aid patient counselling.

Risk of Periprosthetic Joint Infection After Intra-Articular Corticosteroid Injection Following Unicompartmental Knee Arthroplasty

BackgroundPerioperative intra-articular joint injection is a known risk factor for developing prosthetic joint infection (PJI) in the immediate preoperative and postoperative periods for total knee arthroplasty, but is less defined in unicompartmental knee arthroplasty (UKA). The goal of this study was to elucidate the risk of developing PJI after intra-articular corticosteroid injection (IACI) into a post UKA knee. MethodsA retrospective review of a nationwide administrative claims database was performed from January 2015 to October 2020. Patients who underwent UKA and had an ipsilateral IACI were identified and matched 2:1 to a control group of primary UKA patients who did not receive IACI. Multivariate logistic analyses were conducted to assess differences in PJI rates at 6 months, 1 year, and 2 years. ResultsA total of 47,903 cases were identified, of which 2,656 (5.5%) cases received IACI. The mean time from UKA to IACI was 355 days. The incidence of PJI in the IACI group was 2.7%, compared to 1.3% in the control group. The rate of PJI after IACI was significantly higher than the rate in the control group at 6 months, 1 year, and 2 years (all P < .05). The majority of PJI occurred within the first 6 months following IACI (75%). ConclusionIn this study, IACI in a UKA doubled the risk of PJI compared to patients who did not receive an injection. Surgeons should be aware of this increased risk to aid in their decision-making about injecting into a UKA. Level of EvidenceIII, retrospective comparative study.

The Impact of Patient-Reported Penicillin or Cephalosporin Allergy on the Occurrence of the Periprosthetic Joint Infection in Primary Knee and Hip Arthroplasty.

Reducing the risk of periprosthetic joint infections (PJI) requires a multi-pronged strategy including usage of a prophylactic antibiotic. A history of penicillin or cephalosporin allergy often leads to a change in prophylactic antibiotic regimen to avoid serious side effects. The purpose of the present retrospective study was to determine incidence of PJI based on perioperative antibiotic regimen in total hip arthroplasty (THA), total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA). A review of all primary THAs, primary TKAs and primary UKAs, undertaken between 2011 and 2020 in a tertiary referral hospital, was performed. The standard perioperative antibiotic for joint arthroplasty (JA) in the analyzed tertiary hospital is cefuroxime. There were no differences in prophylactic antibiotic regimen over time. In 7.9% (211 of 2666) of knee arthroplasties and in 6.0% (206 of 3419) of total hip arthroplasties, a second-line prophylactic antibiotic was used. There was no statistically significant higher occurrence of PJI between the first-line and second-line prophylactic antibiotic in knee arthroplasties (p = 0.403) as well as in total hip arthroplasties (p = 0.309). No relevant differences in age, American Society of Anesthesiologists (ASA) score and body mass index (BMI) between the groups were observed.

The lifetime revision risk of unicompartmental knee arthroplasty.

Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calculate the 'lifetime risk' of revision for UKA as a more meaningful estimate of risk projection over a patient's remaining lifetime, and to compare this to TKA. Incidence of revision and mortality for all primary UKAs performed from 1999 to 2019 (n = 13,481) was obtained from the New Zealand Joint Registry (NZJR). Lifetime risk of revision was calculated for patients and stratified by age, sex, and American Society of Anesthesiologists (ASA) grade. The lifetime risk of revision was highest in the youngest age group (46 to 50 years; 40.4%) and decreased sequentially to the oldest (86 to 90 years; 3.7%). Across all age groups, lifetime risk of revision was higher for females (ranging from 4.3% to 43.4% vs males 2.9% to 37.4%) and patients with a higher ASA grade (ASA 3 to 4, ranging from 8.8% to 41.2% vs ASA 1 1.8% to 29.8%). The lifetime risk of revision for UKA was double that of TKA across all age groups (ranging from 3.7% to 40.4% for UKA, and 1.6% to 22.4% for TKA). The higher risk of revision in younger patients was associated with aseptic loosening in both sexes and pain in females. Periprosthetic joint infection (PJI) accounted for 4% of all UKA revisions, in contrast with 27% for TKA; the risk of PJI was higher for males than females for both procedures. Lifetime risk of revision may be a more meaningful measure of arthroplasty outcomes than implant survival at defined time periods. This study highlights the higher lifetime risk of UKA revision for younger patients, females, and those with a higher ASA grade, which can aid with patient counselling prior to UKA. Cite this article: Bone Joint J2022;104-B(6):672-679.

Clinical Outcomes of Revision Total Knee Arthroplasty after High Tibial Osteotomy and Unicompartmental Knee Arthroplasty: A Systematic Review and Meta-Analysis.

As more high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are performed, orthopaedic surgeons realize that more HTO and UKA failures will require revision to total knee arthroplasty (TKA) in the future. To systematically evaluate the clinical outcomes of TKA after HTO and TKA after UKA, the Embase, PubMed, Ovid, Web of Science, and Cochrane Library databases were searched for studies investigating revision TKA after HTO and UKA published up to June 2021. RevMan version 5.3 was used to perform the meta‐analysis. The revision TKA after HTO and revision TKA after UKA groups were compared in terms of operative time, range of motion (ROM), knee score, postoperative complications, postoperative infection, revision, and revision implants used. Nine studies were ultimately included in the meta‐analysis. Results revealed that the knee score for the revision TKA after HTO group was better than that of the revision TKA after UKA group (MD 4.50 [95% CI 0.80–8.20]; p = 0.02). The revision TKA after HTO group had a lower revision rate (OR 0.65 [95% CI 0.55–0.78]; p < 0.00001) and fewer revision implants used (OR 0.11 [95% CI 0.05–0.23]; p < 0.00001). There were no statistical differences in operation time (MD ‐2.00 [95% CI −11.22 to 7.21]; p = 0.67), ROM (MD ‐0.04 [95% CI ‐3.69–3.61]; p = 0.98), postoperative complications (OR 1.41 [95% CI 0.77–2.60]; p = 0.27), or postoperative infections (OR 0.89 [95% CI 0.61–1.29]; p = 0.53). To conclude, the revision rate of revision TKA after UKA was greater, and more revision implants were required. It is important for orthopaedic surgeons to preserve bone during primary UKA.

Significant Reduction in Short-Term Complications Following Unicompartmental Versus Total Knee Arthroplasty: A Propensity Score Matched Analysis

BackgroundTotal knee arthroplasty (TKA) is a gold standard surgical treatment for end-stage arthritis and unicompartmental knee arthroplasty (UKA) is an alternative for localized disease in appropriate patients. Both have been shown to have equivalent complications in the short-term period. We aimed to explore the differences in 30-day complication rates between UKA and TKA using recent data. MethodsCurrent Procedural Terminology codes identified patients in the American College of Surgeons National Surgical Quality Improvement Program database who underwent primary TKA or UKA from 2014 to 2018. Propensity score matching addressed demographic differences. Rate of any adverse event (AAE) and complications were compared. ResultsWe identified 279,852 patients with 270,786 and 9,066 undergoing TKA and UKA. No significant difference was observed in baseline demographics after matching. The AAE rate differed significantly between TKA (5.07%) and UKA (2.38%) cohorts (P < .001). TKA group experienced more wound dehiscence, cerebrovascular accident, postoperative blood transfusion, deep vein thrombosis, and requirement for postoperative intubation. Rate of extended length of stay differed between the TKA (11.35%) and UKA (4.89%) cohorts (P < .001). Accounting for all other variables, preoperative corticosteroid use, bleeding disorder, and chronic obstructive pulmonary disease increased the risk for AAE for both groups. Increasing American Society of Anesthesiologists class also increased the odds for complication proportionally with increasing age and operative time. ConclusionContrary to previous data, we found a significantly higher 30-day complication rate in TKA patients. TKA patients had a higher likelihood of having an extended length of stay. Multivariable analysis identified preoperative steroid use, bleeding disorder, and chronic obstructive pulmonary disease as risk factors for developing adverse events for both groups. Level of EvidenceLevel III.

Difference between medial and lateral tibia plateau in the coronal plane: importance of preoperative evaluation for medial unicompartmental knee arthroplasty

BackgroundSetting bone cutting levels for different joint line orientations of the medial and lateral tibia plateaus in individual patients is not clear. We aimed to evaluate the difference between joint line orientation of the medial and lateral tibia plateaus relative to the horizontal line of mechanical axis of tibia as tibial plateau difference (TPD) for an optimal tibial bone cut in medial unicompartmental knee arthroplasty (UKA) and determine which factors could influence TPD. We aimed to investigate the effect of preoperative TPD on polyethylene liner size in medial UKA.MethodsTPD in the coronal plane were measured in 181 female patients (181 knees). To determine the morphology of proximal tibia according to the severity of osteoarthritis, the patients were classified into three groups based on diagnosis and treatment: 80 who underwent robot-assisted medial UKA, 45 who underwent total knee arthroplasty (TKA), and 56 with early-stage osteoarthritis (OA) who had conservative management. Also, we divided the medial UKA group into two groups according to TPD (greater than or less than 5 mm) and compared polyethylene liner sizes.ResultsNo significant difference was observed in TPD (p = 0.662), difference between the medial and lateral femoral condyle levels (p = 0.54), medial proximal tibial angle (p = 0.169), or posterior tibial slope (p = 0.466) among the three groups. Increased TPD was significantly associated with increased mechanical femorotibial angle(mFTA) (p < 0.01). The medial UKA group was divided into two groups according to TPD greater or less than 5 mm. Thicker polyethylene liners were used for groups with TPD greater than 5 mm (8.5 ± 0.7 mm versus 8.2 ± 0.3 mm, p = 0.01). Additionally, the proportion of patients using the thinnest polyethylene (8 mm) in each TPD group (greater or less than 5 mm) was higher in patients with TPD less than 5 mm (82.4% versus 58.7%, p = 0.038).ConclusionsPreoperative measurement of TPD is important to help surgeons predict the most appropriate bone cutting level in the coronal plane in primary medial UKA. Tibial bone resection would be likely to be thicker than needed in patients with increased TPD in medial UKA.

Optimized medial unicompartmental knee arthroplasty outcome: learning from 20 years of propensity score matched registry data.

Background and purposeUnicompartmental knee arthroplasty (UKA) has increased in use. We investigated changes to UKA revision risk over the last 20 years compared with total knee arthroplasty (TKA), examined external and patient factors for correlation to UKA revision risk, and described the survival probability for current UKA and TKA practice.Patients and methodsAll knee arthroplasties reported to the Danish Knee Arthroplasty Register from 1997 to 2017 were linked to the National Patient Register and the Civil Registration System for comorbidity, emigration, and mortality information. All primary UKA and TKA patients with primary osteoarthritis were included and propensity score matched 4 TKAs to 1 UKA. Revision and mortality were analyzed using competing risk cox regression with a shared gamma frailty component.ResultsThe matched cohort included 48,195 primary knee arthroplasties (9,639 UKAs). From 1997–2001 to 2012–2017 the 3-year hazard ratio decreased from 5.5 (95% CI 2.7–11) to 1.5 (CI 1.2–1.8) due to increased UKA survival. Cementless fixation, a high percentage usage of UKA, and increased surgical volume decreased UKA revision risk, and increased in occurrence parallel to the decreasing revision risks. Current UKA practice using cementless fixation at a high usage unit has a 3-year implant survival of 96% (CI 97–95), 1.1% lower than current TKA practice.InterpretationUKA revision risk has decreased over the last 20 years, nearing that of TKA surgery. High usage rates, surgical volume, and the use of cementless fixation have increased during the study and were associated with decreased UKA revision risks.

Is routine blood typing and screening necessary before primary total hip or knee arthroplasty in the 21st century?

Blood loss warranting transfusion is a relatively rare complication of major-joint arthroplasty procedures like total knee arthroplasty (TKA) and total hip arthroplasty (THA). Despite this rarity, pre-transfusion testing (blood typing, screening, and cross-matching) has become routine. We sought to determine if such routine testing is necessary for patients who undergo a primary TKA or THA by (1) measuring the current rate of intraoperative transfusions in primary TKA and THA patients, (2) identifying risk factors for transfusions, and (3) calculating the costs of such blood typing and screening. We retrospectively examined the records of 992 patients who underwent primary TKA, THA, or unicompartmental knee arthroplasty (UKA) to identify patients requiring intra-operative or in-hospital postoperative transfusions. Demographic and baseline clinical and laboratory data also were collected and analyzed to identify predictors of transfusion. Cost analysis was performed. The rate of intraoperative transfusion was 1.7% (17/992 patients), with rates of 2.1%, 1.6%, and 0% for TKA, THA, and UKA respectively. The in-hospital transfusion rate was 10.3%, with corresponding postoperative transfusion rates of 9.1%, 12.9%, and 2%. The only baseline variable significantly linked to transfusions on multivariable analysis was preoperative hemoglobin level, with preoperative Hgb <12 g/dl predictive of transfusions in both TKA (p=.02) and THA (p=.024) patients. Our study suggests that pre-transfusion testing for all patients undergoing primary UKA, TKA or THA is unnecessary. We recommend reserving routine pre-transfusion testing for patients with preoperative hemoglobin levels below 12 g/dl.