The Use of Artificial Neural Networks for the Prediction of Surgical Site Infection Following TKA

This is a retrospective study. Surgical site infection (SSI) is associated with adverse postoperative outcomes following total knee arthroplasty (TKA). However, accurately predicting SSI remains a clinical challenge due to the multitude of patient and surgical factors associated with SSI. This study aimed to develop and validate machine learning models for the prediction of SSI following primary TKA. This is a retrospective study for patients who underwent primary TKA. Chart review was performed to identify patients with superficial or deep SSIs, defined in concordance with the criteria of the Musculoskeletal Infection Society. All patients had a minimum follow-up of 2 years (range: 2.1–4.7 years). Five machine learning algorithms were developed to predict this outcome, and model assessment was performed by discrimination, calibration, and decision curve analysis. A total of 10,021 consecutive primary TKA patients was included in this study. At an average follow-up of 2.8 ± 1.1 years, SSIs were reported in 404 (4.0%) TKA patients, including 223 superficial SSIs and 181 deep SSIs. The neural network model achieved the best performance across discrimination (area under the receiver operating characteristic curve = 0.84), calibration, and decision curve analysis. The strongest predictors of the occurrence of SSI following primary TKA, in order, were Charlson comorbidity index, obesity (BMI >30 kg/m2), and smoking. The neural network model presented in this study represents an accurate method to predict patient-specific superficial and deep SSIs following primary TKA, which may be employed to assist in clinical decision-making to optimize outcomes in at-risk patients.

An ACS-NSQIP Analysis of Unicompartmental Knee Arthroplasty Trends from 2013 to 2018

Unicompartmental knee arthroplasty (UKA) volume has increased with advances in implant design, perioperative protocols, and patient selection. This study analyzed national trends of UKA from 2013 to 2018 and the relationship between patient demographics and postoperative outcomes. Data on UKA (CPT 27446) from 2013 to 2018 was collected from the National Surgical Quality Improvement Program (NSQIP). Variables collected included patient demographics, American Society of Anesthesiology classification, functional status, NSQIP morbidity probability, operative time, length of stay, 30-day reoperation, and readmission rates. There was an increase in outpatient UKAs performed (920 in 2013; 11,080 in 2018) (p < 0.0001). Analysis of variance from 2013 to 2018 revealed significant decrease in patient body mass index (BMI) (32.5 in 2013; 31.5 in 2018) (p < 0.01) and NSQIP morbidity probability (0.014 in 2013; 0.011 in 2018) (p < 0.0001). Operative time increased (79.1 minutes in 2013; 84.4 minutes in 2018) (p < 0.01), but length of stay decreased (0.9 days in 2013; 0.5 days in 2018) (p < 0.0001). The number of all-cause and related readmissions decreased significantly (p < 0.045; p < 0.01). Age, male gender, BMI >40 and chronic obstructive pulmonary disease (COPD) were significant predictors for 30-day readmission. BMI >40 was a significant predictor for discharge destination. UKA has seen a rise in incidence from 2013 to 2018 with an increasing number of outpatient UKAs. Operative times and 30-day readmissions have both decreased in this time. BMI > 40 is predictive for discharge destination after UKA, while age, male gender, BMI >40, and COPD are independent risk factors for 30-day readmission.

Anteromedial Tibial Attachment in Single-Bundle Anterior Cruciate Ligament Reconstruction Can Represent Normal Kinematics in Computer Simulation

Tunnel position during anterior cruciate ligament (ACL) reconstruction is considered as an important factor to restore normal knee kinematics and to gain better clinical outcomes. It is still unknown where the optimal femoral and tibial tunnel position is located in single-bundle (SB) ACL reconstruction. The purposes of this study were to analyze the knee kinematics with various graft positions and to propose the optimal graft position during SB ACL reconstruction. A musculoskeletal computer simulation was used to analyze knee kinematics. Four attachments on the femoral side (anteromedial [AM], mid, posterolateral [PL], and over-the-top positions) and three attachments on the tibial side (AM, middle, and PL positions) were determined. The middle-bundle attachment was placed at the midpoint of the AM and PL bundle attachments for the femoral and tibial attachments. SB ACL reconstruction models were constructed to combine each of the four femoral attachments with each of three tibial attachments. Kinematic comparison was made among a double-bundle (DB) model and 12 SB reconstruction models during deep knee bend and stair descent activity. The tunnel position of the tibia had greater effect of knee kinematics than that of the femur. AM tibial attachment models showed similar medial and lateral anteroposterior positions to the DB model for both activities. Axial rotation in the AM tibial attachment models was similar to the DB model regardless of the femoral attachment, whereas greater maximum axial rotation was exhibited in the PL tibial attachment models, especially during stair descent activity. AM tibial attachment can represent normal knee kinematics, whereas the PL tibial attachment can induce residual rotational instability during high-demand activities. The AM tibial tunnel is recommended for SB ACL reconstruction.

A Randomized Controlled Study on the Use of Tourniquet in Primary Total Knee Arthroplasty

Background The use and the optimal timing of tourniquet during primary total knee arthroplasty (TKA) is controversial. Most previous studies failed to show clinically significant differences in different strategies. The aim of this study was to determine how three strategies of tourniquet application affect the outcome in TKA patients. Methods This was a prospective randomized controlled study. Patients who undergo TKA were randomized into one of the three groups (1:1:1 ratio): tourniquet inflated from skin incision to cement hardening, tourniquet from cement application to hardening, and tourniquet from skin incision to skin closure. The perioperative blood loss, limb swelling, and complications were recorded. The level of hemoglobin, hematocrit, C-reactive protein (CRP), interleukin (IL)-6, creatine kinase (CK), and lactate dehydrogenase (LDH) were determined. Patients' thigh and TKA wound pain, Knee Society knee score (KSKS) and Knee Society functional assessment (KSFA) scores, and rehabilitation parameters were evaluated. Results A total of 90 patients were enrolled. The baseline characteristics were comparable. We only found significant difference in the intraoperative blood loss (skin to cement: 58.7 ± 36.1 mL, cement-only: 147.8 ± 107.9 mL, skin to skin: 16.3 ± 13.1 mL, p < 0.0001). There were no statistical differences in postoperative drainage, thigh/knee circumference, change of hemoglobin/hematocrit, CRP, IL-6, CK, and LDH on day 1 to day 4 after surgery. The thigh/TKA wound Visual Analogue Scale scores, KSKS score, KSFA score, and rehabilitation parameters were not significantly different at up to 6-month follow-up. No thromboembolic events were noted. Conclusion Our results revealed that there was no best tourniquet strategy in TKA. Different tourniquet methods can be utilized based on surgeon preference without affecting outcomes.

An Anatomically Placed Tibial Tunnel does not Completely Surround a Simulated PCL Reconstruction Graft in the Proximal Tibia

Introduction It is hypothesized that anatomic tunnel placement will create tunnels with violation of the posterior cortex and subsequently an oblique aperture that is not circumferentially surrounded by bone. In this article, we aimed to characterize posterior cruciate ligament (PCL) tibial tunnel using a three-dimensional (3D) computed tomography (CT) model. Methods Ten normal knee CTs with the patella, femur, and fibula removed were used. Simulated 11 mm PCL tibial tunnels were created at 55, 50, 45, and 40 degrees. The morphology of the posterior proximal tibial exit was examined with 3D modeling software. The length of tunnel not circumferentially covered (cortex violation) was measured to where the tibial tunnel became circumferential. The surface area and volume of the cylinder both in contact with the tibial bone and that not in contact with the tibia were determined. The percentages of the stick-out length surface area and volume not in contact with bone were calculated. Results The mean stick-out length of uncovered graft at 55, 50, 45, and 40 degrees were 26.3, 20.5, 17.3, and 12.7 mm, respectively. The mean volume of exposed graft at 55, 50, 45, and 40 degrees were 840.8, 596.2, 425.6, and 302.9 mm3, respectively. The mean percent of volume of exposed graft at 55, 50, 45, and 40 degrees were 32, 29, 25, and 24%, respectively. The mean surface of exposed graft at 55, 50, 45, and 40 degrees were 372.2, 280.4, 208.8, and 153.3 mm2, respectively. The mean percent of surface area of exposed graft at 55, 50, 45, and 40 degrees were 40, 39, 34, and 34%, respectively. Conclusion Anatomic tibial tunnel creation using standard transtibial PCL reconstruction techniques consistently risks posterior tibial cortex violation and creation of an oblique aperture posteriorly. This risk is decreased with decreasing the angle of the tibial tunnel, though the posterior cortex is still compromised with angles as low as 40 degrees. With posterior cortex violation, a surgeon should be aware that a graft within the tunnel or socket posteriorly may not be fully in contact with bone. This is especially relevant with inlay and socket techniques.

Preoperative Factors Associated with Press Ganey Patient Satisfaction Scores after Anterior Cruciate Ligament Reconstruction

Patient satisfaction is increasingly used as a metric to evaluate the quality of healthcare services and to determine hospital and physician compensation. The aim of this study was to identify preoperative factors associated with Press Ganey Ambulatory Surgery (PGAS) satisfaction scores, and to evaluate the effect of each PGAS domain score on the total PGAS score variability in patients undergoing anterior cruciate ligament reconstruction (ACLR). A review of a Press Ganey (PG) database at a single center was performed for patients undergoing ACLR between 2015 and 2019. Ninety-nine patients completed the PGAS survey and 54 also completed preoperative demographic and patient-reported outcome measures (PROMs) for an orthopaedic registry. PGAS scores were calculated and bivariate analysis was performed. Multivariable linear regression determined the effect of each of the six PGAS domains on the total PGAS score variability. In the total cohort of 99 patients, no factors were significantly associated with the total PGAS score or any domain scores. For the 54 patients who also participated in the orthopaedic registry, none of the preoperative PROMs were significantly correlated with total PGAS score. However, having a college degree (89 vs. 95 or 97 points; p = 0.02) and continuous femoral nerve catheter (92 vs. 100 points; p = 0.04) was associated with lower personal issue domain scores, while patients with a greater number of prior surgeries had worse registration domain scores (ρ = -0.27; p = 0.049). For the entire cohort, the registration and facility domains contributed the most variability to the total PGAS score, while the physician domain contributed the least. Few preoperative factors are associated with PGAS scores, and total PGAS scores do not significantly correlate with baseline PROMs. Surgeons may have limited ability to improve their PGAS scores given most of the variability in total scores stems from systemic aspects of the patient experience.

The Relationship between the Injury Mechanism and the Incidence of ACL Avulsions in Schatzker Type IV Tibial Plateau Fractures: A 3D Quantitative Analysis Based on Mimics Software

Introduction Tibial plateau fractures are often accompanied with ligamental and meniscal injuries. Among which, the combined existence of Schatzker type IV fracture with anterior cruciate ligament (ACL) avulsion has been reported rarely. The purpose of this study was to determine the injury mechanism of Schatzker type IV fracture with ACL avulsion based on Mimics software. Methods Ninety-nine Schatzker type IV tibial plateau fractures were retrospectively analyzed by quantitative three-dimensional measurements. ACL avulsions were diagnosed through the data of computed tomography and magnetic resonance imaging. We simulated the knee posture when an injury occurred and defined different injury patterns. The chi-square test was used for determining the main mechanism which causes Schatzker type IV fractures associated with ACL avulsions. Results There were more ACL avulsions and more displaced ACL avulsions associated with the knee in flexion in the setting of Schatzker type IV fracture (p < 0.05). More ACL avulsions were found in the injury pattern of flexion-valgus than the other injury patterns of the same level (p < 0.05). The rotation of the tibial showed no significant difference in producing ACL avulsion fractures. Conclusion This study found that a flexed knee at the occurrence of a Schatzker type IV tibial plateau fracture is a high-risk factor for causing associated ACL avulsion and producing more displaced avulsions. Flexion-valgus pattern was the main cause of Schatzker type IV fractures associated with ACL avulsions. The findings will help orthopedists understand the injury mechanism and enhance their awareness of such injuries to avoid unfavorable prognosis.

The BTK Safety Score: A Novel Scoring System for Risk Stratifying Patients Undergoing Simultaneous Bilateral Total Knee Arthroplasty

Selection of appropriate candidates for simultaneous bilateral total knee arthroplasty (si-BTKA) is crucial for minimizing postoperative complications. The aim of this study was to develop a scoring system for identifying patients who may be appropriate for si-BTKA. Patients who underwent si-BTKA were identified in the National Surgical Quality Improvement Program database. Patients who experienced a major 30-day complication were identified as high-risk patients for si-BTKA who potentially would have benefitted from staged bilateral total knee arthroplasty. Major complications included deep wound infection, pneumonia, renal insufficiency or failure, cerebrovascular accident, cardiac arrest, myocardial infarction, pulmonary embolism, sepsis, or death. The predictive model was trained using randomly split 70% of the dataset and validated on the remaining 30%. The scoring system was compared against the American Society of Anesthesiologists (ASA) score, the Charlson Comorbidity Index (CCI), and legacy risk-stratification measures, using area under the curve (AUC) statistic. Total 4,630 patients undergoing si-BTKA were included in our cohort. In our model, patients are assigned points based on the following risk factors: +1 for age ≥ 75, +2 for age ≥ 82, +1 for body mass index (BMI) ≥ 34, +2 for BMI ≥ 42, +1 for hypertension requiring medication, +1 for pulmonary disease (chronic obstructive pulmonary disease or dyspnea), and +3 for end-stage renal disease. The scoring system exhibited an AUC of 0.816, which was significantly higher than the AUC of ASA (0.545; p < 0.001) and CCI (0.599; p < 0.001). The BTK Safety Score developed and validated in our study can be used by surgeons and perioperative teams to risk stratify patients undergoing si-BTKA. Future work is needed to assess this scoring system's ability to predict long-term functional outcomes.

Measurement of Medial Tibial Eminence Dimensions for the Clinical Evaluation of ACL-Injured Knees: A Comparison between CT and MRI

Anterior cruciate ligament (ACL) injuries commonly lead to translational and rotational tibiofemoral instability. The morphology of the medial tibial eminence (MTE) has received increased attention regarding its role in tibiofemoral stability in ACL-injured knees. Therefore, quantification of MTE dimensions on clinical imaging may help clinicians predict knee stability after ACL injury. Although magnetic resonance imaging (MRI) is routinely obtained in patients with ACL injuries, whether the dimensions of the MTE can be accurate quantified on MRI is unknown. The purpose of this study was to assess the degree of correlation between measurements of MTE height and width on computed tomography (CT) versus MRI. An institutional picture archiving and communication system imaging database was used to identify patients aged between 15 and 60 years who received concurrent MRI and CT of the same knee within a 1-year interval. Knees with significant arthrosis, deformity, intraarticular fracture, or hardware-related artifact that obscured visualization of the MTE were excluded. Mean differences and interstudy agreement between CT and MRI MTE measurements were compared using concordance correlation coefficient (r c) and Bland–Altman analysis. A total of 41 knees in 38 patients (mean age, 37 years; 82% male) were analyzed. Interrater reliability for CT and MRI measurements was high (intraclass correlation coefficient = 0.740–0.954). On coronal CT and MRI, mean MTE height measurements were 10.4 ± 1.9 and 10.4 ± 1.8 mm, respectively; mean MTE width measurements were 14.6 ± 3.6 and 14.2 ± 3.0 mm, respectively. On sagittal CT and MRI, mean MTE height measurements were 11.6 ± 1.7 and 11.7 ± 1.7 mm, respectively; mean MTE width measurements were 36.5 ± 4.8 and 36.2 ± 5.0 mm, respectively. Good agreement was observed between CT and MRI measurements of MTE height and width on coronal and sagittal planes (r c = 0.947–0.969). Measurements of MTE height and width were similar on MRI relative to CT on both coronal and sagittal planes. MRI may be suitable for characterizing the dimensions of the MTE when clinically evaluating patients with ACL injuries, potentially allowing for individualized patient care.

Different Doses of Intravenous Tranexamic Acid in Revision Total Knee Arthroplasty: A Retrospective Study

Purpose This article assessed the efficacy and safety of different doses of intravenous tranexamic acid (TXA) in revision total knee arthroplasty (TKA). Methods We retrospectively identified 122 patients in our institution who underwent revision TKA with a history of perioperative intravenous TXA utilization. According to the sum of intravenous TXA documented, all patients were divided into three groups: 1 g intravenous TXA, 2 g intravenous TXA, and equal or greater than 3 g intravenous TXA. The primary outcomes included total blood loss (TBL), hidden blood loss (HBL), transfusion rate, and the incidence of symptomatic venous thromboembolism among the three groups. A correlation analysis was conducted to analyze the correlation between the dose of TXA and the blood loss. Results In total, there was no significance difference in TBL and revised HBL (rHBL) between the first two groups (1 g/dL for intravenous TXA, 2 g/dL for intravenous TXA; p = 0.486; p = 0.525). Equal or greater than 3 g intravenous TXA (≥3 g/dL for intravenous TXA) reached a significant reduction in TBL, rHBL, and length of stay compared with the first two groups (p = 0.01; p = 0.01; p = 0.01). The rate of transfusion between the three groups did not differ significantly (p = 0.21). Due to the limitations in sample size, only one symptomatic venous thromboembolism was reported in the 1 g intravenous TXA group. Conclusion Applying the dose of intravenous TXA equal or greater than 3 g in revision TKA might further reduce the blood loss and shorten the length of stay.