Comparison of Functional Recovery Between Unicompartmental and Total Knee Arthroplasty: A Randomized Controlled Trial

National trends in knee arthroplasty and risk factors for revision surgery: A nationwide population-based cohort study in South Korea

BACKGROUND

This study aimed to examine surgical trends in knee arthroplasty over past 18 years and identify the factors associated with risk of revision surgeries following total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) in South Korea.

METHODS

This study was conducted using National Health Insurance Service - National Sample Cohort database, approximately 1 million individuals from 2002 to 2019. We analyzed general trends and procedural rates of knee arthroplasty, stratified by age, location of residence, and hospital size. Additionally, we investigated the risk factors of knee arthroplasty failure in UKA and TKA.

RESULTS

The average age of the 15,395 individuals who underwent UKA (n = 664) or TKA (n = 14,731) was 69.8 years (standard deviation 7.2), and 77.3% were women. In TKA, occurrence increased by approximately 4.9 times from 2002 to 2010 and by 1.5 times 2010 onward. In contrast, the number of UKA procedures did not increase until 2008, after which it increased 6.1-fold by 2019. An increasing trend in TKA procedures was observed among individuals aged 70-79 and >80 years, whereas the UKA procedural rates increased across all age groups. The revision rate was higher in UKA than that in TKA (13.7% vs. 2.8%). The risk factors were younger age, diabetes mellitus for TKA, and osteoporosis for UKA.

CONCLUSION

Unlike that of TKA, procedural rate increment of UKA occurred in younger people recently and featured a considerably higher revision rate. Given that UKA has a higher revision rate and different risk factors than TKA, monitoring should be tailored specifically for each procedure.

Biomechanical and clinical assessments of activities of daily living following unicompartmental knee arthroplasty: A scoping review

BACKGROUND

Unicompartmental knee arthroplasty is an effective treatment for isolated medial or lateral knee osteoarthritis. Evaluating knee joint loading during activities of daily living postoperatively can offer valuable insights about the compensatory mechanisms in unicompartmental knee arthroplasty patients. The aim of this scoping review was to summarize and to synthesize the existing literature on the most performed activities of daily living and their associated biomechanical outcomes following unicompartmental knee arthroplasty.

METHODS

Five databases, including Medline, Embase, CINAHL, Web of Science, and Ergonomics Abstracts were searched based on 3 main concepts: unicompartmental knee arthroplasty, activities of daily living and biomechanical outcomes. Studies were screened based on titles and abstracts, followed by a full text reading conducted by two authors following inclusion and exclusion criteria.

FINDINGS

This scoping review included 17 studies that met the inclusion criteria and focusing on activities of daily living. These activities were categorized into three main subgroups 1) Stair negotiation, 2) Higher degree of knee flexion activities (including squat, lunge and sit-to-stand) and 3) other activities of daily living (including balance, incline and decline walking).

INTERPRETATION

Stair negotiation was the most evaluated task followed by squatting with a main focus on reporting knee joint kinematics and kinetics. The majority of studies did not report the use of Patient Reported Outcome Measures combined with motion analysis outcomes. Furthermore, most studies focused primarily on medial knee arthroplasty with a fixed-bearing design in short-term follow-up which warrants caution when generalizing these findings to all types of unicompartmental knee arthroplasty.

Inpatient cost comparison of total and unicompartmental knee arthroplasty in patients with medial compartmental osteoarthritis using time-driven activity-based costing

PURPOSE

Using time-driven activity-based costing (TDABC), we sought to compare the total facility costs, comprising supply and personnel costs during the episode of care for the index procedure, in patients with isolated medial compartmental knee osteoarthritis (OA) undergoing unicompartmental knee arthroplasty (UKA) versus total knee arthroplasty (TKA).

METHODS

We conducted a retrospective analysis of 100 UKAs and 100 TKAs from 2019 to 2022. From a larger sample of 4899 TKAs and 137 UKAs, patients with isolated medial OA (Kellgren-Lawrence Grade <2 in other compartments) were radiographically identified. Demographic data included age, sex and body mass index, with comorbidities controlled using the Charlson comorbidity index. Facility costs were calculated using TDABC and standardized in cost units (CUs), a metric for comparing costs across procedures. Multiple regression analysis was used to assess the independent effect of TKA versus UKA on facility costs.

RESULTS

TKA patients had similar operative times (TKA vs. UKA: 1.01×, p = 0.783) and supply costs (1.00×, p = 0.866), where 'x' denotes the relative cost ratio. However, TKA was associated with higher personnel costs (260.0 vs. 222.5 CUs [1.17×], p < 0.001) and total facility costs, both including (706.3 vs. 667.5 CUs [1.06×], p = 0.007) and excluding implants (353.8 vs. 312.5 CUs [1.13×], p < 0.001). Adjusted for demographics and comorbidities, TKA had increased facility costs, including (32.2 CUs, 95% confidence interval [CI]: 2.9-61.5, p = 0.031) and excluding implants (37.8 CUs, 95% CI: 15.2-60.3, p = 0.001).

CONCLUSIONS

TDABC analysis revealed higher total facility costs for the index procedure in TKA, suggesting UKA may be a cost-saving alternative for isolated medial compartment knee OA.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Comparing Functional Recovery Between Total and Unicompartmental Knee Arthroplasty: A Prospective Health Kit Study

BACKGROUND

Both total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) have demonstrated excellent clinical outcomes for end-stage osteoarthritis. Although UKA has been shown to have lower survivorship, many patients are interested in a partial knee arthroplasty due to the perception of "better" function and a "quicker" recovery. The purpose of this study was to objectively compare and understand functional recovery between TKA and UKA through the utilization of cutting-edge technological health metrics.

METHODS

Over a 2-year period, 185 patients undergoing TKA or UKA (152 versus 33, respectively) were prospectively followed for 1 year postoperatively. Smart devices were worn by these patients to track their daily steps, steadiness, standing time, 6-minute walk test, and gait speed, and were averaged weekly at multiple time points ranging from immediately preoperatively to 1 year postoperatively. Propensity matching scores were conducted in a 1:3 UKA to TKA ratio, resulting in a final cohort of 120 patients undergoing TKA or UKA (87 versus 33). Additionally, EuroQol 5 dimension survey and Knee Injury and Osteoarthritis Outcome scores were compared between groups.

RESULTS

At 6 weeks postoperatively, the mean gait speed was quicker for patients who underwent a UKA in comparison to those who underwent a TKA (0.97 versus 0.89 meters/second, P = 0.02). Furthermore, the average steadiness at 6 weeks postoperatively was better in the UKA group when compared to the TKA cohort (0.60 versus 0.40 (0 to 1 scale), P = 0.03). No further differences were demonstrated between groups at the 6-week time point. No data or reported outcomes varied between the UKA and TKA cohorts at both 6-month and 1-year postoperative time points.

CONCLUSIONS

This prospective study compared UKA and TKA through the incorporation of real-time objective technological data. Although steadiness and gait speed were better in the UKA group at the 6-week follow-up, no differences existed beyond this time point. This study demonstrates that both UKA and TKA had the same recovery and functionality in regards to gait speed, daily step counts, standing time, steadiness, and the 6-minute walking test at 6-month and 1-year follow-up.

Correction of severe varus deformity in total knee arthroplasty with the technique of tibial plateau reduction

BACKGROUND

The optimal soft tissue release technique for severe varus total knee arthroplasty (TKA) remains controversial. The technique of tibial plateau reduction was suggested for severe varus deformity during TKA. The purpose of this study was to evaluate the clinical and radiological outcomes of the technique of tibial plateau reduction.

METHODS

Fifty-one knees (39 patients) with a mechanical femoro-tibial angle (MFTA) greater than 15° treated with TKA was presented. The clinical and radiographic data were gathered prospectively. The patients were divided into two groups according to the preoperative angle: Group A comprised patients with a preoperative MFTA less than or equal to 20°, while Group B included patients with a preoperative MFTA greater than 20°.

RESULTS

Among the 51 knees, 46 knees (90.2%) had femoro-tibial component size mismatch. The KSS-KS improved from preoperative 39.9 ± 11.3 points (range:18-68 points) to 92.3 ± 5.2 points (range: 83-100 points) at the final follow up (t = 30.141, P < 0.001); the KSS-FS improved from preoperative 48.0 ± 11.5 points (range: 31-71 points) to 87.2 ± 8.7 points (range: 63-100 points) at the final follow up (t = 19.413, P < 0.001). The mean MFTA was corrected from 21.0 ± 4.7° preoperatively to 2.9 ± 1.8° at the latest follow up (P < 0.001). The preoperative MFTA was less than or equal to 20° in 27 knees (Group A), and greater than 20° in 24 knees (Group B). The mean postoperative MFTA was 1.9 ± 0.9° in Group A, and 4.1 ± 1.7° in Group B (P < 0.001). The neutral limb alignment was reached in 26 knees (96.3%) in group A, which was significantly higher than that in group B (29.7%) (P = 0.019).

CONCLUSIONS

The technique of tibial plateau reduction provided satisfactory clinical and radiological outcomes without instability for severe varus TKA. However, surgeons should remain aware that the greater the preoperative varus deformity, the greater the postoperative residual varus deformity, and that there is a high incidence of femoro-tibial component size mismatch using the technique.

Measured Resection as Gap Balance Method in Mobile-Bearing Medial Unicompartmental Knee Arthroplasty: A Randomized Controlled Trial

OBJECTIVE

Gap balancing is a vital process during mobile-bearing unicompartmental knee arthroplasty (MB-UKA). However, this process commonly depends on the surgeon's experience and lacks specific unified standards. This study aimed to propose and evaluate a novel "measured resection" method for gap balance in MB-UKA.

METHODS

This prospective study included 49 consecutive patients (52 knees) who underwent MB-UKA from February 1, 2023, to September 1, 2023. Gap balance was achieved by the traditional "two-finger" method (Group 1, 26 knees) or the measured resection method (Group 2, 26 knees). The novel "measured resection" method was performed by measuring the thickness of the resected posterior femoral condyle and resected medial posterior tibial plateau to assess proper meniscal bearing thickness. Data were collected at baseline and the 6-month follow-up. Prosthetic angles, range of motion (ROM), visual analog scale (VAS) score, Oxford knee score (OKS), and Global Perceived Scale (GPE) were used to evaluate clinical outcomes. Independent samples t-test and Mann-Whitney U test were used to compare the differences.

RESULTS

There were significant improvements in all measured outcomes at the 6-month follow-up from baseline in both groups (p < 0.01). Patients using measured resection method showed better ROM (130° vs. 120°, p = 0.007), VAS score (1 vs. 2, p = 0.013), and OKS scores (39.9 vs. 38.1, p = 0.013) at 6-month follow-up than the traditional "two-finger" method group. The prosthetic angles, ROM improvement, and GPE showed no significant difference between the groups (p > 0.05).

CONCLUSIONS

The measured resection method is a reliable method for assisting surgeons in choosing the ideal meniscal bearing thickness in MB-UKA to achieve proper gap balance and gain better clinical outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT03815448).

Comparison of clinical outcomes of bilateral and unilateral unicompartmental knee arthroplasty for the treatment of knee osteoarthritis

The risks and benefits associated with simultaneous bilateral unicompartmental knee arthroplasty (UKA) continue to engender contentious debate. The aim of this study was to compare the clinical outcomes of simultaneous bilateral and unilateral UKA. A retrospective review was performed between 2019 and 2022 on 280 patients (130 simultaneous bilateral vs. 150 unilateral Oxford UKA) who performed by two experienced surgeons. Patients in both groups underwent surgery according to the Microplasty instrumentation system, with congruent postoperative management and carefully standardized follow-up. This study performed a comparative analysis between the two groups of patients with regard to postoperative laboratory tests, knee functionality, postoperative discomfort, and incidence of complications. There was a significant difference in the duration of disease between the two groups (U-UKA:6.05 vs. SB-UKA:7.80, P < 0.05). When it comes to laboratory examinations, a notable disparity emerged in hemoglobin levels, erythrocyte pressure volume, D-dimer concentrations, albumin levels, as well as indicators of inflammation among the two groups of patients (P < 0.05). There was a significant difference in operative time and blood loss between the two groups (P < 0.05), with no significant difference in complications. There was no significant difference in radiographic and prosthetic survival between the two groups (U-UKA: 99.3% vs. 98.5%). The HSS score, VAS, and ROM showed remarkable disparities between the two groups in the initial postoperative phase, albeit these distinctions gradually attenuated with the passage of time. Simultaneous bilateral UKA reduces the number of procedures without increasing the risk of surgical complications, but results in a markedly enhanced physiological response and a suboptimal perioperative experience. We strongly encourage the surgeon to work with the patient to determine a surgical strategy.

A systematic comparative analysis of gait characteristics in patients undergoing total knee arthroplasty and unicompartmental knee arthroplasty: a review study

BACKGROUND

This study systematically reviews recent research comparing clinical outcomes and gait function changes in patients undergoing total knee arthroplasty (TKA) versus unicompartmental knee arthroplasty (UKA).

METHODS

A systematic search of the Web of Science, PubMed, and Embase databases was conducted, covering publications from January 2013 to September 2024, to identify studies evaluating changes in clinical scores and gait parameters in patients undergoing TKA or UKA. Following stringent selection criteria, data were synthesized from studies involving 171 TKA and 148 UKA patients, focusing on reported gait outcomes and aggregating findings for comprehensive analysis. Direct comparisons between TKA and UKA were performed to assess differences in clinical scores and gait parameters, aiming to elucidate the relative efficacy of each surgical approach and provide robust evidence for clinical decision-making.

RESULTS

Ten studies met the inclusion criteria for post-operative gait outcome comparisons between TKA and UKA, with seven studies also addressing clinical scores. One study reported greater improvement in WOMAC scores for the UKA group at 6 months post-operation (P < 0.05), while another found superior EQ-5D scores for UKA patients at 1 year post-surgery (P < 0.05). Conversely, five studies found no significant differences in clinical scores between groups at 1 year (P > 0.05). All ten studies assessed gait parameter recovery, with three studies showing no significant differences at 1 year (P > 0.05). However, seven studies identified superior gait recovery in the UKA group across various parameters, including walking speed, step and stride length, single support time, heel strike force, knee joint range of motion, knee flexion angles during different gait phases, peak knee adduction moment, peak tibial internal rotation moment, gait symmetry, and stride length symmetry (P < 0.05).

CONCLUSIONS

The analysis indicates that UKA offers certain advantages in post-operative gait improvements compared to TKA, though these do not translate into significant differences in conventional clinical scoring systems. To enhance the reliability and generalizability of these findings, future studies should involve larger-scale, prospective randomized controlled trials.

New technology: Custom made implants, patient-specific alignment, and navigation - How to convince my hospital it's worth it: Current concepts

Unicompartmental knee arthroplasty (UKA) faces significant challenges, including lower survival rates and higher revision rates than total knee arthroplasty (TKA). To address these issues, technological advancements like custom-made implants (CMI), patient-specific alignment (PSA), and computer-assisted systems (CAS) are being explored. These innovations aim to tailor procedures to individual joint morphology, soft tissue balance, and limb alignment, moving away from the traditional "one size fits all" approach. Early studies suggest that CMI may improve survival rates and patient-reported outcomes, though conclusive evidence is lacking. PSA shows potential for restoring pre-surgical alignment; however, its long-term benefits are uncertain. CAS improves implant placement precision and ligament balance; nevertheless, long-term survival data remain inconclusive. Moreover, economic and implementation challenges, such as cost and the need for specialized training, remain underexplored. While promising, further research is needed to fully understand the long-term efficacy and practical application of these technologies in UKA.

Unicompartmental knee arthroplasty in octogenarians: An analysis of 1,466 patients with 2-year follow-up

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) has been shown to improve pain and function in appropriately selected patients. Limited data exists regarding outcomes and complication rates following UKA among octogenarians.

METHODS

The PearlDiver Mariner database was queried for patients undergoing primary UKA between 2010-2022. Patients < 80 years old were matched 4:1 to the octogenarian cohort (≥80 years old) by sex, year, Elixhauser Comorbidity Index (ECI), tobacco use, obesity, and diabetes. A total of 1,334 octogenarians and 5,313 controls were included in our analysis. Multivariate logistic regression was utilized to compare medical complications at 90-days post-operatively and surgical complications at 1- and 2-years post-operatively. Our regression analysis controlled for sex, ECI, tobacco use, obesity, and diabetes.

RESULTS

Octogenarians had an increased risk of acute kidney injury (OR: 2.306, 95% CI: 1.393-3.749; p < 0.001), pneumonia (OR: 2.367, 95% CI: 1.301-4.189; p = 0.003), UTI (OR: 1.846, 95% CI: 1.304-2.583; p < 0.001), ED visits (OR: 2.229, 95% CI: 1.586-3.105; p < 0.001), and any complication (OR: 1.575, 95% CI: 1.304-1.895; p < 0.001) at 90-days post-operatively. Octogenarians had lower odds of all-cause revision at 2-years (OR: 0.607, 95% CI: 0.382-0.923; p = 0.026). No differences were demonstrated between cohorts in rates of PJI (OR: 0.832, 95% CI: 0.334-1.796; p = 0.664), periprosthetic fracture (OR: 0.516, 95% CI: 0.120-1.520; p = 0.289), or aseptic loosening (OR: 0.285, 95% CI: 0.045-1.203; p = 0.088) at 2-years.

DISCUSSION

These findings suggest that despite an increased risk of certain medical complications within the acute post-operative period, octogenarians undergoing UKA experienced similar rates of surgical complications to younger matched controls at 2-year follow-up.

Clinical outcomes of unicompartmental knee arthroplasty and total knee arthroplasty in the same patient

BACKGROUND

Osteoarthritis has become the predominant manifestation of arthritic conditions on a worldwide scale and serves as a significant instigator of pain, impairment, and increasing socio-economic strain on a global level. The ongoing discourse on the choice between total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) for patients suffering from anterior medial osteoarthritis continues to ignite scholarly controversy. Our objective was to assess and compare the clinical outcomes of UKA and TKA within the same patient, hereby offering a novel perspective on this topic.

MATERIALS AND METHODS

Fifty-seven individuals who underwent TKA on one knee and UKA on the other knee at the Department of Orthopaedics, First Hospital of Hebei Medical University between March 2019 and March 2024 were analysed for this retrospective study. We conducted a comprehensive examination and evaluation of perioperative laboratory assessments, radiological examinations, knee functionality, contentment levels, and postoperative complications within the two groups.

RESULTS

Following surgical procedures, levels of hemoglobin, red blood cells, and albumin were found to be elevated in the UKA group when compared to the TKA group (hemoglobin: 121.2 ± 12.54 vs. 110.1 ± 13.21 g/L; red blood cells: 4.0 ± 0.47 vs. 3.6 ± 0.42 *1012/L; albumin: 37.7 ± 5.66 vs. 35.3 ± 5.23 g/L). There is a significant difference in the hip-knee-ankle angles between the postoperative UKA group and the TKA group (5.3 ± 3.46° vs. 4.1 ± 2.86°, p < 0.05). There existed no notable disparity in postoperative visual analog scale, knee society score, and forgotten joint score between the two groups. However, a remarkable variance was observed in postoperative range of motion between the two groups (116.4 ± 5.96° vs. 108.4 ± 5.32°).

CONCLUSION

We found that UKA resulted in less physical strain, less postoperative inflammatory response, improved joint mobility, although with less effective lower limb force line correction compared to TKA. Many patients have shown a preference for UKA and express higher levels of satisfaction with the procedure.

Daily physical activity following unicompartmental knee arthroplasty: A pilot study

Purpose

The purpose of this study was to understand how objective measures of daily activity change following unicompartmental knee arthroplasty (UKA). Objective data on post-operative changes in daily physical activity following UKA are limited, highlighting the need for studies using wearable technologies to provide real-time assessments of recovery.

Methods

This pilot study included a secondary analysis of a prospective study of 33 consecutive UKA patients, with data collected using an Apple Watch and a digital care management application. Objective metrics, including step count, steadiness, standing duration and performance on the six-minute walk test, were analyzed at different post-operative time points. Descriptive statistics and the Wilcoxon signed-rank test were used for analysis.

Results

Post-operatively, there was a significant increase in daily step count at 6 weeks (p = 0.017), 6 months (p < 0.001) and 12 months (p = 0.0018). Steadiness improved significantly at 6 months (p = 0.049) and 12 months (p = 0.039) post-operatively. Standing duration increased significantly at all the post-operative time points (p < 0.001). Gait speed did not show significant changes post-operatively. The estimated six-minute walk test distance improved significantly at 6 months (p = 0.027) and 12 months (p = 0.031) post-operatively.

Conclusion

The study findings suggest that UKA improves daily physical activity levels, reflected by enhanced mobility and function. While gait speed did not significantly change, improvements in step count, steadiness, standing duration and the six-minute walk test distance indicate enhanced functional capacity and endurance post-operatively. The study highlights the benefits of UKA in improving functional outcomes in patients with knee osteoarthritis. Further research with larger sample sizes and longer follow-ups is warranted to confirm these findings.

Levels of Evidence

II.

Gender does not influence outcomes and complications in medial unicompartmental knee arthroplasty

PURPOSE

The impact of gender on the outcomes of unicompartmental knee arthroplasty (UKA) remains a topic of active discussion with limited exploration thus far. The study aims to elucidate the gender effect on clinical outcomes, complications, pre- and postoperative radiological outcomes following the implantation of a medial UKA at mid-term follow-up in a large section of patients.

METHODS

This was a single-centre, retrospective cohort study encompassing patients undergoing medial UKA between 2011 and 2019. The International Knee Society (IKS) Knee and Function score, patient satisfaction, complications, revisions, pre- and postoperative radiological outcomes (coronal plane alignment, femoral and tibial component positioning, posterior tibial slope) were evaluated. Survival rate at the time of the last follow-up was also recorded.

RESULTS

Of the 366 knees that met the inclusion criteria, 10 were lost to follow-up, accounting for a 2.7% loss. Mean follow-up was 5.2 ± 2 years [2.1-11.3]. Out of the total population, 205 patients were females (57.6%, 205/356) and 151 were males (42.4%, 151/356). Men exhibited superior pre- and postoperative IKS function scores (p = 0.017). However, no significant differences were observed between women and men regarding improvements of IKS Knee and Function scores, radiographic outcomes and implant survivorship.

CONCLUSION

At a mean follow-up of 5 years, this study revealed no significant impact of gender on clinical outcomes and complications in patients undergoing medial UKA. Furthermore, no significant differences were evident in radiographic outcomes, implant positioning and knee phenotype.

LEVEL OF EVIDENCE

Level III.

Comparative long-term outcomes of unicompartmental and total knee arthroplasty in knee osteoarthritis patients: a systematic review and meta-analysis

Background

Long-term outcomes for knee osteoarthritis patients undergoing unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) remain inconclusive.

Objectives

This study aims to evaluate the long-term outcomes over five years, including Knee Society Pain Scores (KSPS), Knee Society Scores (KSS), Knee Society Function Scores (KSFS), range of motion (ROM), and survival rates-of UKA vs. TKA in knee osteoarthritis patients.

Design

Systematic review using data from randomized controlled and cohort trials, and world databases.

Data sources

Researchers searched Medline, Embase, Cochrane Controlled Register of Trials, and ClinicalTrials.gov from January 1990 to March 2024.

Eligibility criteria for selecting studies

The researchers selected studies based on adult participants with knee osteoarthritis. Eligible studies compare UKA and TKA reports on clinical or surgical outcomes, including KSPS, KSS, KSFS, ROM and survival rates, over 5 years. The researchers excluded the studies fewer than five years, or if English text was unavailable.

Results

Researchers categorized twenty-nine eligible studies into three groups: five randomized controlled trials, 11 registries and database studies, and 13 cohort studies. The analysis revealed that neither TKA nor UKA definitively outperformed the other in terms of pain (SMD (95% CI): -0.06 [-0.41, 0.28], I 2 = 90%) and KSS scores (SMD (95% CI): -0.07 [-0.23, 0.008], I 2 = 81%) over a period of five years. However, KSFS (SMD (95% CI): -0.30 [-0.43, -0.17], I 2 = 74%) and ROM (SMD (95% CI): -0.78 [-1.11, -0.46], I 2 = 92%) tended to favor UKA, and survival rate favor TKA at 5 or over 5-year follow-up periods.

Conclusions

UKA shows a trend towards better outcomes in KSFS and ROM, alongside a more favorable survival rate in TKA at the five-year and beyond follow-up periods.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=517835, PROSPERO (CRD42024517835).

Is unicompartmental knee arthroplasty a better choice than total knee arthroplasty for unicompartmental osteoarthritis? A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The choice of unicompartmental knee arthroplasty (UKA) vs. total knee arthroplasty (TKA) in the surgical treatment of knee osteoarthritis (KOA) remains controversial. This study aimed to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) to compare the clinical results of UKA and TKA for treating unicompartmental KOA.

METHODS

PubMed, Embase, and the Cochrane Library were systematically searched for articles published up to January 2, 2023. The literature was rigorously screened to include only RCTs comparing UKA and TKA for unicompartmental KOA. A systematic review and meta-analysis were performed to calculate the mean difference (MD), relative risk (RR), and 95% confidence interval (CI) according to the Cochrane standards.

RESULTS

Thirteen publications involving 683 UKAs and 683 TKAs were analyzed. Except for one study with a follow-up period of 15 years, all outcome measures reported were within 5 years of follow-up. Meta-analysis showed better knee recovery (MD: 1.23; 95% CI: 1.01-1.45; P <0.00001), greater knee function (MD: 1.78; 95% CI: 0.34-3.22; P = 0.02), less pain (MD: 0.75; 95% CI: 0.43-1.06; P <0.00001), and better health status (MD: 3.75; 95% CI: 0.81-6.69; P = 0.01) after UKA than TKA. However, considering the minimal clinically important difference values for these variables, the findings were not clinically relevant. Moreover, UKA patients had fewer complications (RR: 0.59; 95% CI: 0.45-0.78; P = 0.0002) and shorter hospital stays (MD: -0.89; 95% CI: -1.57 to -0.22; P = 0.009) than did TKA patients. There were no statistically significant differences in terms of postoperative range of movement, revision, failure, operation time, and patient satisfaction.

CONCLUSIONS

In terms of clinical efficacy, there was no obvious advantage of UKA over TKA in the surgical treatment of knee OA when considering the minimal clinically important difference. The main advantage of UKA over TKA is that it leads to fewer complications and a shorter length of hospital stay. It is ideal to perform prospective studies with longer follow-up periods to fully evaluate the long-term efficacy and safety of the two procedures in the future.

Joint line convergence angle is the most associated alignment factor with the severity of medial knee osteoarthritis

Purpose

The purpose of this study was to evaluate the relationship between the joint line convergence angle (JLCA) and the severity of medial knee osteoarthritis (OA). We hypothesise that JLCA is the most associated factor with the severity of medial knee OA.

Methods

This retrospective study included a total of 202 knees that underwent either high tibial osteotomy or medial meniscus repair/partial resection. Kellgren-Lawrence grade and hip-knee-ankle angle (HKAA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA) and JLCA were assessed from preoperative radiographs. Medial meniscus extrusion (MME) was measured using preoperative magnetic resonance imaging. The International Cartilage Research Society (ICRS) grade on the medial femoral condyle and medial tibial plateau were also assessed. The relationships between JLCA and Kellgren-Lawrence grades and MME and ICRS grades were analysed using Spearman's correlation test and regression analysis.

Results

The JLCA was correlated with the Kellgren-Lawrence grade (R = 0.765, p < 0.001), MME (R = 0.638, p < 0.001), ICRS grade on the MFC (R = 0.586, p < 0.001) and the MTP (R = 0.586, p < 0.001). Regression analysis showed that age (p = 0.002) and JLCA (p < 0.001) were associated with Kellgren-Lawrence grade. Furthermore, JLCA was related to ICRS grade on the MFC (p < 0.001) and MTP (p < 0.001).

Conclusion

The JLCA, reflecting radiological severity, meniscus status, and cartilage lesion, was the most associated alignment parameter in the severity of medial knee OA. The JLCA may be beneficial for quantitative assessment of medial knee OA.

Level of Evidence

Level III, retrospective cohort study.

Robotic-arm-assisted conversion of unicompartmental knee arthroplasty to total knee arthroplasty

Introduction

The purpose of this study was to describe a novel robotic-arm-assisted UKA to TKA conversion technique and evaluate the patient reported and clinical outcomes in these patients.

Methods

A retrospective review between 2017 and 2022 was conducted of patients that underwent robotic-arm-assisted UKA to TKA conversion. Charts were reviewed for patient demographics, indications for conversion from UKA to TKA, operative technique, implants used, postoperative complications, and patient-reported outcome measures (PROMs). The surgical technique resembles that of primary TKA, with the major exception of registering the robotic arm with retained UKA implants and removing the implants only when verification is complete. There were 44 robotic-arm-assisted UKAs in 41 patients were included in the study. Indications for UKA conversion to TKA included: 33 patients who had osteoarthritis progression (75%), 7 aseptic loosening (16%), 2 unspecified pain (4.5%), 1 polyethylene wear (2.3%), and 1 prosthetic joint infection (2.3%). Uncemented cruciate-retaining (CR) implants were used in 38 of the 44 robotic-arm-assisted TKAs (86.5%). The other six utilized cemented implants: four CR femurs (9.1%), six tibial baseplates (13.6%), four tibial stems (9.1%), and four medial tibial augments (9.1%).

Results

The PROMs significantly improved at 1-year follow-up, with the average KOOS JR score increasing from 48.1 to 68.7 (P < 0.001), and the r-WOMAC score decreasing from 25.7 to 10.6 (P = 0.003). Two patients developed prosthetic joint infections (4.5%), one developed aseptic loosening of the femoral component (2.3%), and one developed a superficial surgical site infection requiring superficial irrigation and debridement (2.3%). Overall survivorship was 93.18% at 1.8 years, and aseptic survivorship was 97.73%.

Conclusion

Robotic-arm-assisted UKA to TKA conversion exhibited improved patient-reported outcomes and low revision and complication rates. Improved implant placement achieved with robotic-arm-assistance may improve the functional and clinical outcomes following these surgeries.

Small change in the arithmetic hip-knee-ankle angle during unicompartmental knee arthroplasty improves early postoperative functional outcomes

INTRODUCTION

The optimal lower-limb alignment after unicompartmental knee arthroplasty (UKA) remains controversial. This study aimed to investigate the optimal lower-limb alignment for functional improvement in the early post-UKA period. We hypothesized that a small change (Δ) in the arithmetic hip-knee-ankle (aHKA) angle during surgery would result in better postoperative knee function.

MATERIALS AND METHODS

This single-centered, retrospective study analyzed 91 patients (91 knees) who underwent UKA from April 2021 and December 2022. Preoperative and postoperative standing whole-leg radiographs were used to evaluate the mechanical HKA angle and aHKA angle. The aHKA angle was calculated from the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). We defined restored aHKA angle as a postoperative aHKA angle within ± 3° of the preoperative aHKA angle. Functional improvement was evaluated using the preoperative and one-year postoperative Knee Society Scoring 2011 (KSS 2011). A multivariate regression analysis was performed to investigate the optimal lower-limb alignment for functional improvement.

RESULT

Postoperative restored aHKA angle (p = 0.020) was the only significant factor for improved KSS 2011 scores. Postoperative restored aHKA angle was obtained in 64 patients (70%). ΔMPTA (p < 0.001) and ΔLDFA (p = 0.037) were significant factors associated with a postoperative restored aHKA angle.

CONCLUSIONS

UKA restores the native knee, including resurfacing constitutional alignment and medial collateral ligament tension. Minimal change in the aHKA angle during UKA improves the functional outcomes of the knee during the early postoperative period, consistent with the minimally invasive surgical concept of UKA.

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

BACKGROUND

Patients 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.

METHODS

Patients 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.

RESULTS

351 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.

CONCLUSION

The 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.

Unicompartmental knee arthroplasty questionnaire (UniQ-study): Unknown is unloved

BACKGROUND

Almost 50% of the patients requiring knee replacement are suitable for medial unicompartmental knee arthroplasty (UKA). However, national registries have shown a use far below 50%.

AIM

The aim of this study was to identify the factors that could influence the use of UKA.

METHODS

A questionnaire was conducted among practicing knee surgeons of the Dutch Orthopedic Association. The questionnaire was classified into three domains: surgeon, patient selection, and professional opinion. Associations between the domains and UKA volume and contra-indications were tested using Pearson's chi-square tests.

RESULTS

Of the 113 included respondents, 40% had no hands-on exposure during residency. Frequently reported contra-indications were obesity (68%), lateral osteophytes (21%), chondrocalcinosis (20%), and age (20%). Medial partial thickness lesions were considered a contra-indication by 49% and lateral joint space narrowing by 61% of the respondents. Respondents perceived UKA to outperform total knee arthroplasty regarding all outcomes, except survival (1.8% versus 42%). The reported barriers for UKA use were insufficient experience (20%), high revision rates (20%), and low hospital volume (16%), whereas 60% did not experience any at all. Hands-on UKA exposure during residency was associated with an increased use of correct indications. Furthermore, the use of correct indications was associated with an increased UKA volume.

CONCLUSION

We showed a low UKA exposure during residency and considerable variations in contra-indications. These factors may contribute to an underuse of UKA. Improved UKA training could lead to increased experience and better patient selection among surgeons and consequently a higher use of medial UKA.

First Italian Experience with the Oxinium Metal-Backed Fixed-Bearing Medial Journey II Unicompartmental Knee System: Promising Short-Term Outcomes of 145 Cases

(1) Background: Unicompartmental knee arthroplasty (UKA) provides a viable alternative to total knee arthroplasty (TKA) in patients with isolated medial osteoarthritis (OA). From 2007 to 2021, 23% of all primary knee arthroplasties in Italy were UKAs. We retrospectively evaluated clinical outcomes and satisfaction in patients implanted with a new oxinium metal-backed fixed-bearing medial unicompartmental prosthesis at a 24-month follow-up. (2) Methods: From December 2020 to December 2021, 145 patients were treated by a single surgeon at a single institution using the hypoallergenic Journey II prosthesis. Clinical outcome measures included the Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), Oxford Knee Society (OKS) score, University of California Los Angeles Activity Score (UCLA), the Physical Component Summary (PCS), and the Mental Component Summary (MCS), and were calculated preoperatively and at 12 and 24 months. The Forgotten Joint Score-12 (FJS-12) was calculated at 12 and 24 months. Patient satisfaction was collected at 24 months. The scores were compared using the Friedman test. (3) Results: All clinical scores improved significantly from baseline to 24 months (p < 0.0001), except for the FJS-12, which from 12 to 24 months did not improve significantly (p = 0.041). Patient satisfaction was 9.32 ± 0.74 out of 10. No patient experienced complications or required revision surgery. (4) Conclusions: The Journey II unicompartmental prosthesis is a valuable treatment option for end-stage medial OA, improving knee function, providing pain relief, and ensuring high patient satisfaction at 24 months.

The impact of elective total hip and knee arthroplasty on physical performance in orthogeriatric patients: a prospective intervention study

BACKGROUND

Osteoarthritis is a prevalent condition in older adults that leads to reduced physical function in many patients and ultimately requires hip or knee replacement. The aim of the study was to determine the impact of hip and knee arthroplasty on the physical performance of orthogeriatric patients with osteoarthritis.

METHODS

In this prospective study, we used data from 135 participants of the ongoing Special Orthopaedic Geriatrics (SOG) trial, funded by the German Federal Joint Committee (GBA). Physical function, measured by the Short Physical Performance Battery (SPPB), was assessed preoperatively, 3 and 7 days postoperatively, 4-6 weeks and 3 months after hip and knee arthroplasty. For the statistical analysis, the Friedman test and post-hoc tests were used.

RESULTS

Of the 135 participants with a mean age of 78.5 ± 4.6 years, 81 underwent total hip arthroplasty and 54 total knee arthroplasty. In the total population, SPPB improved by a median of 2 points 3 months after joint replacement (p < 0.001). In the hip replacement group, SPPB increased by a median of 2 points 3 months after surgery (p < 0.001). At 3 months postoperatively, the SPPB increased by a median of 1 point in the knee replacement group (p = 0.003).

CONCLUSION

Elective total hip and knee arthroplasty leads to a clinically meaningful improvement in physical performance in orthogeriatric patients with osteoarthritis after only a few weeks.

TRIAL REGISTRATION

This study is part of the Special Orthopaedic Geriatrics (SOG) trial, German Clinical Trials Register DRKS00024102. Registered on 19 January 2021.

Survival of Patient-Specific Unicondylar Knee Replacement

Unicompartmental knee arthroplasty (UKA) in isolated medial or lateral osteoarthritis leads to good clinical results. However, revision rates are higher in comparison to total knee arthroplasty (TKA). One reason is suboptimal fitting of conventional off-the-shelf prostheses, and major overhang of the tibial component over the bone has been reported in up to 20% of cases. In this retrospective study, a total of 537 patient-specific UKAs (507 medial prostheses and 30 lateral prostheses) that had been implanted in 3 centers over a period of 10 years were analyzed for survival, with a minimal follow-up of 1 year (range 12 to 129 months). Furthermore, fitting of the UKAs was analyzed on postoperative X-rays, and tibial overhang was quantified. A total of 512 prostheses were available for follow-up (95.3%). Overall survival rate (medial and lateral) of the prostheses after 5 years was 96%. The 30 lateral UKAs showed a survival rate of 100% at 5 years. The tibial overhang of the prosthesis was smaller than 1 mm in 99% of cases. In comparison to the reported results in the literature, our data suggest that the patient-specific implant design used in this study is associated with an excellent midterm survival rate, particularly in the lateral knee compartment, and confirms excellent fitting.

Partial versus total knee arthroplasty for isolated antero-medial osteoarthritis - An analysis of PROMs and satisfaction

AIM

This study aimed to compare the patient-reported functional outcomes and patient satisfaction after medial Unicompartmental Knee Arthroplasty (UKA) versus Total Knee Arthroplasty (TKA), performed for anteromedial osteoarthritis (AMOA) of the knee in patients from an Indian population, at a minimum 3-year follow-up.

METHODS

This is a prospective matched cohort study (1:2 ratio). One hundred and one UKA cases were matched to 206 TKA cases by propensity score matching for age, body mass index (BMI), gender distribution, and the Charlson Comorbidity Index (CCI). The primary outcome (Oxford knee score, OKS) was assessed at a 3-year follow-up, along with secondary outcomes (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] Score, Forgotten Joint Score (FJS), Anterior Knee Pain (Kujala) score, patient satisfaction, and revision rate at the final follow-up).

RESULTS

The UKA group was superior to the TKA group in patient-reported functional outcomes based on the OKS (p = 0.004). Using the FJS score, UKA was more likely to be a forgotten joint compared to TKA (p < 0.001). However, differences in the OKS and FJS did not meet the reported minimal clinically important difference (MCID) thresholds. Quality of life (EuroQol-5D VAS scale) was found to be significantly higher in the UKA group (p < 0.001). Patients in the UKA group were more likely to be very satisfied (75.2%) versus the TKA group (62.1%, p = 0.023).

CONCLUSION

For AMOA, UKA was associated with improved patient satisfaction compared to TKA. Although patient-reported outcome measures were statistically in favour of UKA over TKA, the differences were not clinically significant. Multicenter and randomized studies comparing the two procedures are warranted.

EVIDENCE

Level-II Therapeutic.