Unicompartmental knee arthroplasty is associated with lower proportions of surgical site infection compared with total knee arthroplasty: A retrospective nationwide database study

Unexpected positive cultures in revision total knee arthroplasty after unicompartmental knee arthroplasty

PURPOSE

Unexpected positive cultures are defined as a single positive culture in intraoperative samples taken during revision surgery after prosthetic joint infection was preoperatively ruled out. This study aims to determine the prevalence of unexpected positive cultures (UPC) in revision total knee arthroplasty (TKA) after unicompartmental knee arthroplasty (UKA). As a secondary objective, this study aims to compare the re-intervention rate in this specific group, between UPC and non-UPC patients. The hypothesis is that the UPC prevalence in patients who undergo a revision TKA after UKA is not higher than in other TKA revision cases and this does not increase the risk of re-intervention.

METHODS

This is a retrospective study where all patients who underwent a UKA revision from January 2016 to February 2023 in a high-volume arthroplasty centre, were analyzed. Unexpected positive culture prevalence in this group of patients was obtained.

RESULTS

During the included period, 270 UKA revision surgeries were performed. Eight cases had at least two positive cultures and were therefore excluded. The final analysis included 262 patients. Of these, 8 (3.05%) patients presented UPCs and the isolated microorganisms were low-virulence organisms. None of the UPC patients received any treatment. No statistical differences were found between UPC and non-UPC groups in the analyzed variables.

CONCLUSION

The prevalence of unexpected positive cultures in patients following revision of unicompartmental knee arthroplasty is lower than in patients who undergo a revision of total knee arthroplasty. In UKA patients a UPC does not seem to increase the risk of a re-intervention, so it can be safely ignored if ICM criteria are not met.

Advantages and limitations of mobile-bearing unicompartmental knee arthroplasty: an overview of the literature

INTRODUCTION

Interest in unicompartmental knee arthroplasty (UKA) has recently grown. Mobile bearing UKA, in which the bearing is not fixed but rather perfectly conforms with femoral and tibial components and moves completely passively between the femoral and tibial implant, has now been used for approximately half a century.

AREAS COVERED

Alongside the recognized advantages of UKA, the mobile-bearing variant benefits from an extremely low rate of polyethylene wear and tolerable minor malalignment. Revision rates for UKA have been reported to exceed those of total knee arthroplasty, but long-term survival rates and outcomes from mobile-bearing UKA have been found to be satisfactory. In addition to the lateral osteoarthritis and loosening, which are main complications of UKA, bearing dislocation is a specific complication of mobile bearing UKA. Fractures and valgus subsidence are more prevalent than in the cementless UKA. While these continue to be features to be addressed, they have been partially solved.

EXPERT OPINION

Given the manifold benefits of UKA, its application could be extended to a larger patient population. Successful outcomes rely on careful patient selection and the surgeon's extensive familiarity with the procedure. Looking ahead, the incorporation of robotic surgery, already a feature of some fixed-bearing UKAs, might shape the future trajectory of mobile-bearing UKA.

Late summer is a risk factor for periprosthetic joint infection after total joint arthroplasty: A retrospective cohort study

To explore whether season is a risk factor of periprosthetic joint infection (PJI) after total joint arthroplasty (TJA) and explain it with the theory of traditional Chinese medicine. This was a retrospective cohort study. Only patients who suffered from PJI within 1 month after TJA were included in the study. Occurrence of PJI was the outcome of this study. Chi-squared test and t test was used to assess differences for baseline characteristics. Chi-square test was used to analyze whether season was related to the occurrence of PJI. Logistic regression was used to evaluate the association between season and occurrence of PJI. The incidence of PJI in summer is significantly higher than that in winter, whether after total knee arthroplasty (Chi-square value = 6.455, P = .011) or total hip arthroplasty (Chi-square value = 6.141, P = .013). Summer was an independent risk factor for PJI (OR = 4.373, 95% confidence interval = 1.899-10.673, P = .004). To be more exact, compared to nonlate summer (19.51%), and PJI is mainly concentrated in late summer (80.49%). Late summer was an independent risk factor of PJI after TJA. The infection rate of PJI after TJA in late summer is higher than other seasons. A more thorough preoperative disinfection procedure is needed in late summer.

Unicompartmental knee arthroplasty: A French multicenteric retrospective descriptive study from 2009 to 2019 with projections to 2050

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) is a reliable and reproducible procedure. While some surgeons have incorporated it into their therapeutic armamentarium, others do not use it routinely, leading to a large disparity in practice. The objective of this study was to investigate in France the epidemiology of UKA from 2009 to 2019 to identify: (1) the evolution of growth trends by sex and age, (2) the evolution of the state of comorbidity of patients during the operation, (3) the evolution of trends according to the regions, (4) the projection best suited to the observations at 2050.

HYPOTHESIS

Our hypothesis was that in France, an increase would be observed over the period studied, differing according to the characteristics of the population.

MATERIALS AND METHOD

The study was conducted in France over the 2009-2019 period for each gender and age group. The data was taken from the NHDS (National Health Data System) database, which includes all the procedures carried out in France. Based on the collection of procedures performed, the incidence rates (per 100,000 inhabitants) and their evolution were deduced, as well as the indirect assessment of the patient's comorbidity status. Using linear, Poisson, and logistic projection models, incidence rates were projected to the years 2030, 2040, and 2050.

RESULTS

Between 2009 and 2019, the incidence rate of UKA increased sharply (from 12.76 to 19.57; +53%), the growth was different in men (from 10.78 to 20.34; +89%) and women (from 14.61 to 18.85; +29%). The male/female sex ratio increased from 0.69 in 2009 to 1.0 in 2019. The increase was greatest among men under 65 (from 4.9 to 9.9; +100%) and lowest among women over 75 (from 41.2 to 40.5; -2%). Over the period studied, the proportion of patients with mild comorbidities (HPG1) increased (from 71.7% to 81.1%) at the expense of the other classes with more severe comorbidities. This dynamic was observed for all age groups: 0-64 years (from 83.3% to 90%), 65-74 years (from 81.4% to 88.4%), 75 years and over (38 .2% to 52.6%) regardless of sex. There was a strong disparity between the regions with a change in the incidence rate ranging from -22% (from 29.8 to 23.1) for Corsica to +251% (from 13.9 to 48.7) for Brittany. The proposed projection models suggested an increase in the incidence rate of +18% in logistic regression, +103% in linear regression by 2050.

DISCUSSION

Our study showed strong growth in the number of UKAs in France over the period studied, being highest in young men. The proportion of patients with fewer comorbidities increased for all age groups. A disparity in inter-regional practice was identified, with indications that remain ambiguous and differ according to the practitioner. We can expect continued growth in the years to come, adding to the care burden.

LEVEL OF EVIDENCE

IV; Descriptive epidemiological study.

Analysis of revision rates and complication rates among patients undergoing unicompartmental and bicompartmental knee Arthroplasties when compared to Total knee arthroplasty

BACKGROUND

With recent advances in partial knee arthroplasty, there is conflicting data regarding the outcomes and revision rates for bicompartmental knee arthroplasty (BKA) and unicompartamental knee arthroplasty (UKA) compared to total knee arthroplasty (TKA). This study uses national data to compare surgical and medical complications of UKA, BKA, and TKA to aid surgical decision-making.

METHODS

A retrospective cohort analysis was done using the Mariner dataset of the PearlDiver patient records database from 2010-2019. Current Procedural Terminology (CPT) codes were used to identify patients who underwent UKA, BKA, and TKA for a primary indication of osteoarthritis (OA). Univariate and multivariable analyses were performed to determine 1-year and 2-year revision, prosthetic joint infection (PJI), and loosening, 1-year manipulation under anesthesia (MUA), and 90-day postoperative medical complications.

RESULTS

The BKA cohort was found to have higher odds of one and two-year revision compared to UKA and TKA cohorts. Additionally, the UKA cohort had higher odds of one and two-year revision but lower odds of 1-year MUA than the TKA cohort. However, both the BKA and UKA cohorts had lower odds of any 90-day postoperative complications when compared to the TKA cohort.

CONCLUSIONS

Even with modern implants and approaches, our study found that revision rates are highest for BKA followed by UKA and TKA at two years postoperatively. Notably, medical complications were much less common after all partial knee replacement types when compared to TKA. These findings may be used to guide patients in selecting the appropriate surgery to meet their goals and expectations.

The Performance of Diagnostic Tests for Identifying Periprosthetic Joint Infection After Failed Partial Knee Arthroplasty

BACKGROUND

Indications for unicompartmental knee arthroplasty (UKA) and patello-femoral arthroplasty are expanding. Despite the lower published infection rates for UKA and patello-femoral arthroplasty than total knee arthroplasty, periprosthetic joint infection (PJI) remains a devastating complication and diagnostic thresholds for commonly utilized tests have not been investigated recently. Thus, this study evaluated if diagnostic thresholds for PJI in patients who had a failed partial knee arthroplasty (PKA) align more closely with previously reported thresholds specific to UKA or the 2018 International Consensus Meeting on Musculoskeletal Infection.

METHODS

We identified 109 knees in 100 patients that underwent PKA with eventual conversion to total knee arthroplasty within a single healthcare system from 2000 to 2021. Synovial fluid nucleated cell count and synovial polymorphonuclear percentage in addition to preoperative serum erythrocyte sedimentation rate, serum C-reactive protein, and serum white blood cell count were compared with Student's t-tests between septic and aseptic cases. Receiver operating characteristic curves and Youden's index were used to assess diagnostic performance and the optimal cutoff point of each test.

RESULTS

Synovial nucleated cell count, synovial polymorphonuclear percentage, and serum C-reactive protein demonstrated excellent discrimination for diagnosing PJI with an area under the curve of 0.97 and lower cutoff values than the previously determined UKA specific criteria. Serum erythrocyte sedimentation rateESR demonstrated good ability with an area under the curve of 0.89.

CONCLUSION

Serum and synovial fluid diagnostic thresholds for PJI in PKAs align more closely with the thresholds established by the 2018 International Consensus Meeting as compared to previously proposed thresholds specific to UKA.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Obesity increases the risk of conversion to total knee arthroplasty after unicompartimental knee arthroplasty: a meta-analysis

PURPOSE

The aim of this meta-analysis was to to determine the influence of obesity on patient outcome and implant survivorship after primary unicompartmental knee arthroplasty (UKA).

METHODS

A PRISMA systematic review was conducted by searching the Medline (PubMed), EMBASE, and Cochrane electronic databases to identify clinical studies investigating the effect of obesity on outcomes after UKA. Data were collected on aspecifically designed extraction form. Methodological quality was assessed using the Methodological Index for Nonrandomized Studies score. Quantitative meta-analysis was carried out using RevMan 5.4 software.

RESULTS

A total of 17 studies were included; 43,845 primary UKA patients were classified by their BMI: on-obese (BMI 25 to < 30 kg/m²); obese (BMI 30 to < 35 kg/m²); severely obese (BMI > 35 kg/m²). Pooled analysis showed no statistically significant difference in Knee Society Score (KSS) pain in the obese (n.s.) and the severely obese (n.s.) group compared to the non-obese group, while the KSS function score was lower in the severely obese (P = 0.0002) compared to the obese (P = 0.06) and the non-obese group. Postoperative Oxford Knee Score (OKS) was lower in the obese group (P = 0.01) but not in the severely obese group (P = 0.16). Postoperative Range of Motion (ROM) was comparable in the obese and non-obese group (P = 0.16). Implant survival at 10 years follow-up was significantly lower in the obese (82.5-95.3%; P < 0.0001) and the severely obese group (87.5-93.8%; P < 0.0001) thanthe non-obese group (83.6-98.6%).

CONCLUSION

Obesity and severe obesity were associated with significantly higher revision and lower implant survival rates. Obesity did not influence clinical and most functional outcomes after UKA, whereas KSS function score was significantly lower only for the severely obese patient group.

LEVEL OF EVIDENCE

III, meta-analysis.

Risk factors associated with surgical site infections following joint replacement surgery: a narrative review

Background

Surgical site infection following joint replacement surgery is still a significant complication, resulting in repeated surgery, prolonged antibiotic therapy, extended postoperative hospital stay, periprosthetic joint infection, and increased morbidity and mortality. This review discusses the risk factors associated with surgical site infection.

Related risk factors

The patient-related factors include sex, age, body mass index (BMI), obesity, nutritional status, comorbidities, primary diagnosis, living habits, and scores of the American Society of Anesthesiologists physical status classification system, etc. Surgery-related factors involve preoperative skin preparation, prolonged duration of surgery, one-stage bilateral joint replacement surgery, blood loss, glove changes, anti-microbial prophylaxis, topical anti-bacterial preparations, wound management, postoperative hematoma, etc. Those risk factors are detailed in the review.

Conclusion

Preventive measures must be taken from multiple perspectives to reduce the incidence of surgical site infection after joint replacement surgery.