Feasibility of a self‐assembling peptide hydrogel scaffold for meniscal defect: An in vivo study in a rabbit model

The inner avascular zone of the meniscus has limited healing capacity as the area is poorly vascularized. Although peptide hydrogels have been reported to regenerate bone and cartilage, their effect on meniscus regeneration remains unknown. We tested whether the self‐assembling peptide hydrogel scaffold KI24RGDS stays in the meniscal lesion and facilitates meniscal repair and regeneration in an induced rabbit meniscal defect model. Full‐thickness (2.0 mm diameter) cylindrical defects were introduced into the inner avascular zones of the anterior portions of the medial menisci of rabbit knees (n = 40). Right knee defects were left empty (control group) while the left knee defects were transplanted with peptide hydrogel (KI24RGDS group). Macroscopic meniscus scores were significantly higher in the KI24RGDS group than in the control group at 2, 4, and 8 weeks after surgery. Histological examinations including quantitative and qualitative scores indicated that compared with the control group, the reparative tissue in the meniscus was significantly enhanced in the KI24RGDS group at 2, 4, 8, and 12 weeks after surgery. Immunohistochemical staining showed that the reparative tissue induced by KI24RGDS at 12 weeks postimplantation was positive for Type I and II collagen. KI24RGDS is highly biocompatible and biodegradable, with strong stiffness, and a three dimensional structure mimicking native extracellular matrix and RGDS sequences that enhance cell adhesion and proliferation. This in vivo study demonstrated that KI24RGDS remained in the meniscal lesion and facilitated the repair and regeneration in a rabbit meniscal defect model.     

Can Machine Learning Methods Produce Accurate and Easy-to-Use Preoperative Prediction Models of One-Year Improvements in Pain and Functioning After Knee Arthroplasty?

BackgroundApproximately 15%-20% of total knee arthroplasty (TKA) patients do not experience clinically meaningful improvements. We sought to compare the accuracy and parsimony of several machine learning strategies for developing predictive models of failing to experience minimal clinically important differences in patient-reported outcome measures (PROMs) 1 year after TKA.MethodsPatients (N = 587) in 3 large Veteran Health Administration facilities completed PROMs before and 1 year after TKA (92% follow-up). Preoperative PROMs and electronic health record data were used to develop and validate models to predict failing to experience at least a minimal clinically important difference in Knee Injury and Osteoarthritis Outcome Score (KOOS) Total, KOOS JR, and KOOS subscales (Pain, Symptoms, Activities of Daily Living, Quality of Life, and recreation). Several machine learning strategies were used for model development. Ten-fold cross-validation and bootstrapping were used to produce measures of overall accuracy (C-statistic, Brier Score). The sensitivity and specificity of various predicted probability cut-points were examined.ResultsThe most accurate models produced were for the Activities of Daily Living, Pain, Symptoms, and Quality of Life subscales of the KOOS (C-statistics 0.76, 0.72, 0.72, and 0.71, respectively). Strategies varied substantially in terms of the numbers of inputs required to achieve similar accuracy, with none being superior for all outcomes.ConclusionModels produced in this project provide estimates of patient-specific improvements in major outcomes 1 year after TKA. Integrating these models into clinical decision support, informed consent and shared decision making could improve patient selection, education, and satisfaction.Level of EvidenceLevel III, diagnostic study.     

Diagnostic Utility of Platelet Count/Lymphocyte Count Ratio and Platelet Count/Mean Platelet Volume Ratio in Periprosthetic Joint Infection Following Total Knee Arthroplasty

BackgroundDiagnosing a periprosthetic joint infection (PJI) can be challenging and often requires a combination of clinical and laboratory findings. Monocyte/lymphocyte ratio, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio (PLR), and platelet/mean platelet volume ratio (PVR) are simple predictors for inflammation that can be readily obtained from complete blood count. The aim of this study is to evaluate the diagnostic utility of these markers in predicting PJI in total knee arthroplasty (TKA) patients.MethodsA total of 538 patients who underwent revision TKA with calculable marker ratios prerevision in 2 groups were evaluated: (1) 206 patients with a preoperative diagnosis of PJI (group I) and (2) 332 patients treated for revision TKA for aseptic failures (group II). The diagnostic abilities of the markers were assessed via receiver operator characteristic curve analysis.ResultsThe optimal threshold of PVR at 30.82 had the highest sensitivity of 87.7%, while the optimal threshold of PLR at 234.13 had the highest specificity of 82.5%. Both PLR and PVR, when combined with Musculoskeletal Infection Society thresholds for erythrocyte sedimentation rate, C-reactive protein, synovial WBC, and PMN%, achieve significantly higher sensitivity and specificity rates for PJI at or above 97% (PLR: 99.03%; 98.80%; PVR: 98.54%;97.89%).ConclusionOur study demonstrates that PVR and PLR, which are readily available and inexpensive to obtain from complete blood counts, when combined with serum and synovial fluid markers have increased sensitivity and specificity comparable to that of alpha defensin. This suggests that PVR and PLR can be used together with other hematologic and aspirate markers to increase the accuracy of PJI diagnosis in TKA patients.     

Impact of Compensated Cirrhosis Etiology on Postoperative Outcomes Following Total Knee Arthroplasty

BackgroundCirrhotics often demonstrate worse outcomes than their non-cirrhotic counterparts following orthopedic surgery; however, there are limited arthroplasty-focused data on this occurrence. Additionally, variances in postoperative outcomes among the different etiologies of cirrhosis have not been well described. The aim of this study is to evaluate the effect compensated cirrhosis had on postoperative outcomes following elective total knee arthroplasty (TKA).MethodsIn total, 1,734,568 patients who underwent primary TKA from 2006 to 2013 were identified using the Medicare Claims Database. Patients were divided into those with a history of compensated cirrhosis and those with no history of liver disease. Subgroup analysis was performed based on the etiology of cirrhosis. Multivariate logistic regression was used to evaluate postsurgical outcomes of interest.ResultsCirrhotic patients had higher risk of developing disseminated intravascular coagulation (odds ratio [OR] 2.76, P = .003), encephalopathy (OR 3.00, P < .001), and periprosthetic infection (OR 1.79, P < .001) compared to controls. Following subgroup analysis, alcoholic cirrhotics had high risk of periprosthetic infection (OR 2.12, P < .001), fracture (OR 3.28, P < .001), transfusion (OR 2.45, P < .001), and encephalopathy (OR 7.34, P < .001) compared to controls. Viral cirrhosis was associated with an increase in 90-day charges ($14,941, P < .001) compared to controls, while cirrhosis secondary to other causes was associated with few adverse outcomes compared to controls.ConclusionLiver cirrhosis is an independent risk factor for increased perioperative morbidity and financial burden following TKA. Cirrhosis due to etiologies other than viral infections and alcoholism are associated with few adverse outcomes. Surgeons should be aware of these complications to properly optimize postoperative management.     

Bibliometric Analysis of the Top-Cited Articles on Unicompartmental Knee Arthroplasty

BackgroundUnicompartmental knee arthroplasty (UKA) has been proven to be an effective surgical technique for unilateral compartment osteoarthritis. The purpose of this study is to identify and analyze the top 100 cited articles in the field of UKA research.MethodsPublications on UKA from 1980 to 2020 in the Web of Science database were retrieved. The characteristics of the top 100 cited articles were analyzed, including information of publications and citations, level of evidence, and research interests.ResultsThe number of publications and citations increased over time. The majority of the highly cited articles were from the Nuffield Orthopedic Centre (Oxford, England) and the Brigham and Women’s Hospital (Boston, USA). Long-term outcome of UKA and comparison between UKA and TKA gathered most research interests. The most frequently occurring keywords were “survival” and “revision.” Since 2012, “life quality” and “robotics” have been used. There was no level I evidence, and most studies provided level IV evidence.ConclusionThere was a rising trend in publications and citations in the field of UKA research, the majority of them were from a few centers, and were low-level evidence. Most studies focused on the long-term outcomes of UKA; in recent years, patient satisfaction and navigation surgery have become new research trends.     

Closed Incision Negative Pressure Wound Therapy for Elective Hip and Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BackgroundPersistent wound drainage after total joint arthroplasty (TJA) increases the risk of surgical site infections (SSIs). Closed incision negative pressure wound therapy (ciNPWT) decreases infections in traumatic wounds, but evidence for its use after elective TJA is limited. The purpose of this meta-analysis of level I studies is to determine the effect of ciNPWT on risk of SSI and wound complications following TJA.MethodsMEDLINE, EMBASE, CINAHL, and Cochrane Library were searched for randomized controlled trials comparing ciNPWT vs standard dressings after total hip (THA) and total knee arthroplasty (TKA). Studies exclusively involving THA for femoral neck fractures were excluded. Risk of SSI and noninfectious wound complications (blisters, seroma, hematoma, persistent drainage, dehiscence, and wound edge necrosis) following TJA were analyzed.ResultsSSI risk was lower with ciNPWT compared to standard dressings (3.4% vs 7%; relative risk [RR] 0.48, P = .007), specifically in revision THA and TKA (4.1% vs 10.5%; RR 0.41, P = .03). ciNPWT increased the noninfectious complication risk after primary TKA (RR 4.71, P < .0001), especially causing wound blistering (RR 12.66, P < .0001). ciNPWT decreased hospital length of stay by 0.73 days (P = .04) and reoperation rate (RR 0.28, P = .01).ConclusionciNPWT decreases SSI risk compared to standard dressings after revision TJA, but not primary TJA. ciNPWT is associated with >12-fold increased risk of wound blistering after primary TKA. ciNPWT plays a role in revision TJA management, but additional randomized controlled trials with uniform wound assessment methods must be performed to sufficiently power findings and draw conclusions on the use of ciNPWT after primary TJA.     

Projected Economic Burden of Periprosthetic Joint Infection of the Hip and Knee in the United States

BackgroundIn addition to the significant morbidity and mortality associated with periprosthetic joint infection (PJI), the cost of treating PJI is substantial. Prior high-quality national estimates of the economic burden of PJI utilize data up to 2009 to project PJI growth in the United States through 2020. Now in the year 2020, it is appropriate to evaluate these past projections and incorporate the latest available data to better understand the current scale and burden of PJI in the United States.MethodsThe Nationwide Inpatient Sample (2002-2017) was used to identify rates and associated inpatient costs for primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) and PJI-related revision TKA and THA. Poisson regression was utilized to model past growth and project future rates and cost of PJI of the hip and knee.ResultsUsing the most recent data, the combined annual hospital costs related to PJI of the hip and knee were estimated to be $1.85 billion by 2030. This includes $753.4 million for THA PJI and $1.1 billion for TKA PJI, in that year. Increases in PJI costs are mainly attributable to increases in volume. Although the growth in incidence of primary THA and TKA has slowed in recent years, the incidence of PJI and the cost per case of PJI remained relatively constant from 2002 to 2017.DiscussionUnderstanding the current and potential future financial burden of PJI for surgeons, patients, and healthcare systems is essential. There is an urgent need for efficacious preventive strategies in reducing rates of PJI after THA and TKA.     

Effects of Posterior Tibial Slope on a Posterior Cruciate Retaining Total Knee Arthroplasty Kinematics and Kinetics

BackgroundIt has been hypothesized that increasing posterior tibial slope can influence condylar rollback and play a role in increasing knee flexion. However, the effects of tibial slope on knee kinematics are not well studied. The objective of this study is to assess the effects of tibial slope on femorotibial kinematics and kinetics for a posterior cruciate retaining total knee arthroplasty design.MethodsA validated forward solution model of the knee was implemented to predict the femorotibial biomechanics of a posterior cruciate retaining total knee arthroplasty with varied posterior slopes of 0°-8° at 2° intervals. All analyses were conducted on a weight-bearing deep knee bend activity.ResultsIncreasing the tibial slope shifted the femoral component posteriorly at full extension but decreased the overall femoral rollback throughout flexion. With no tibial slope, the lateral condyle contacted the polyethylene 6 mm posterior of the midline, but as the slope increased to 8°, the femur shifted an extra 5 mm, to 11 mm posterior of the tibial midline. Similar shifts were observed for the medial condyle, ranging from 7 mm posterior to 13 mm posterior, respectively. Increasing posterior slope decreased the posterior cruciate ligament tension and femorotibial contact force.ConclusionThe results of this study revealed that, although increasing the tibial slope shifted the femur posteriorly at full extension and maximum flexion, it reduced the amount of femoral rollback. Despite the lack of rollback, a more posterior location of condyles suggests lower chances of bearing impingement of the posterior femur and may explain why increasing slope may lead to higher knee flexion.     

Early and Direct Rehab Transfer Leads to Significant Cost Savings and Decreased Hospital Length of Stay for Total Joint Arthroplasty in a Veteran Population

BackgroundTotal joint arthroplasty is the most common elective orthopedic procedure in the Veterans Affairs hospital system. In 2019, physical medicine and rehabilitation began screening patients before surgery to select candidates for direct transfer to acute rehab after surgery. The primary outcome of this study was to demonstrate that the accelerated program was successful in decreasing inpatient costs and length of stay (LOS). The secondary outcome was to show that there was no increase in complication, reoperation, and readmission rates.MethodsA retrospective review of total joint arthroplasty patients was conducted with three cohorts: 1) control (n = 193), 2) transfer to rehab orders on postop day #1 (n = 178), and 3) direct transfers to rehab (n = 173). To assess for demographic disparities between cohorts, multiple analysis of variance tests followed by a Bonferroni P-value correction were used. Differences between test groups regarding primary outcomes were assessed with analysis of variance tests followed by pairwise t-tests with Bonferroni P-value corrections.ResultsThere were no significant differences between the cohort demographics or comorbidities. The mean total LOS decreased from 7.0 days in the first cohort, to 6.9 in the second, and 6.0 in the third (P = .00034). The mean decrease in cost per patient was $14,006 between cohorts 1 and 3, equating to over $5.6 million in savings annually. There was no significant change in preintervention and postintervention short-term complications (P = .295).ConclusionsSignificant cost savings and decrease in total LOS was observed. In the current health care climate focused on value-based care, a similar intervention could be applied nationwide to improve Veterans Affair services.     

Trends of Prosthetic Joint Infection Organisms and Recurrence for a Single High-Volume Arthroplasty Surgeon Over 20 Years

BackgroundProsthetic joint infection (PJI) is a morbid complication following total joint arthroplasty (TJA). PJI diagnosis and treatment has changed over time, and patient co-management with a high-volume musculoskeletal infectious disease (MSK ID) specialist has been implemented at our institution in the last decade.MethodsWe retrospectively evaluated all consecutive TJA patients treated for PJI between 1995 and 2018 by a single high-volume revision TJA surgeon. Microbial identities, antibiotic resistance, prior PJI, and MSK ID consultation were investigated.ResultsIn total, 261 PJI patients (median age 66 years, interquartile range 57-75) were treated. One-year and 5-year reinfection rates were 15.8% (95% confidence interval [CI] 11.6-20.7) and 22.1% (95% CI 17.0-27.7), respectively. Microbial identities and antibiotic resistances did not change significantly over time. Despite seeing more prior PJI patients (53.3% vs 37.6%, P = .012), MSK ID-managed patients had similar infection rates as non-MSK ID-managed patients (hazard ratio [HR] 1.02, 95% CI 0.6-1.75, P = .93). Prior PJI was associated with higher reinfection risk (HR 2.39, 95% CI 1.39-4.12, P = .002) overall and in patients without MSK ID consultation, specifically (HR 2.78, 95% CI 1.37-5.65, P = .005). This risk was somewhat lower and did not reach significance in prior PJI patients with MSK ID consultation (HR 1.97, 95% CI 0.87-4.48, P = .106).ConclusionWe noted minimal differences in microbial/antibiotic resistances for PJI over 20 years in a single institution, suggesting current standards of PJI treatment remain encouragingly valid in most cases. MSK ID involvement was not associated with lower reinfection risk overall; however, in patients with prior PJI, the risk of reinfection appeared to be somewhat lower with MSK ID involvement.Level of EvidenceLevel IV–Case Series.