An Advanced Knee Simulator Model Can Reproducibly Be Used for Ligament Balancing Training during Total Knee Arthroplasty.

A critical and difficult aspect of total knee arthroplasty (TKA) is ligamentous balancing for which cadavers and models have played a large role in the education and training of new arthroplasty surgeons, although they both have several shortcomings including cost, scarcity, and dissimilarity to in vivo ligament properties. An advanced knee simulator (AKS) model based on computed tomography (CT) scans was developed in the setting of these challenges with cadavers and previous models. In this study, we compared the ligament balancing between AKS and human cadaveric knees to assess the validity of using the AKS for ligament balancing training during TKA. A CT scan of a TKA patient with varus deformity was used to design the AKS model with modular components, using three-dimensional printing. Three fellowship-trained arthroplasty surgeons used technology-assisted TKA procedure to plan and balance three cadaver knees and the AKS model. Medial and lateral laxity data were captured using manual varus and valgus stress assessments for cadavers and the model in an extension pose (10 degrees of flexion from terminal extension) and between 90 and 95 degrees for flexion. After preresection assessments, surgeons planned a balanced cruciate-retaining TKA. Following bony cuts and trialing, extension and flexion ligament laxity values were recorded in a similar manner. Descriptive statistics and Student's t-tests were performed to compare the cadavers and model with a p-value set at 0.05. Preresection medial/lateral laxity data for both extension and flexion were plotted and showed that the highest standard deviation (SD) for the cadavers was 0.67 mm, whereas the highest SD for the AKS was 1.25 mm. A similar plot for trialing demonstrated that the highest SD for the cadavers was 0.6 mm, whereas the highest SD for the AKS was 0.61 mm. The AKS trialing data were highly reproducible when compared with cadaveric data, demonstrating the value of the AKS model as a tool to teach ligament balancing for TKA and for future research endeavors.

Robotic-assisted Total Knee Arthroplasty Technology Provides a Repeatable and Reproducible Method of Assessing Soft Tissue Balance.

Soft-tissue balancing is an important factor in primary total knee arthroplasty (TKA), with 30 to 50% of TKA revisions attributed to technical operative factors including soft-tissue balancing. Robotic-assisted TKA (RATKA) offers opportunities for improved soft-tissue balancing methods. This study aimed to evaluate the repeatability and reproducibility of ligamentous laxity assessments during RATKA using a digital tensioner.Three experienced RATKA surgeons assessed preresection and trialing phases of 12 human cadaveric knees with varying degrees of arthritis. Ligamentous laxity was assessed with manual varus and valgus stresses in extension and flexion, with a digital tensioner providing feedback on the change of laxity displacement. Intraclass correlation coefficient (ICC) analyses were used to determine the repeatability within a single surgeon and reproducibility between the three surgeons.The results showed excellent repeatability and reproducibility in ligamentous laxity assessment during RATKA. Surgeons had excellent repeatability for preresection and trialing assessments, with median ICC values representing excellent reproducibility between surgeons. Surgeons were repeatable within 1 or 1.5 mm for preresection and trialing assessments. On average, the variation within a surgeon was 0.33 ± 0.26 mm during preresection and 0.29 ± 0.28 mm during trialing. When comparing surgeons to each other, they were reproducible within an average of 0.69 ± 0.33 mm for preresection and 0.65 ± 0.31 mm for trialing.This study demonstrated the reliability of robotic-assisted soft-tissue balancing techniques, providing control over ligamentous laxity assessments, and potentially leading to better patient outcomes. The digital tensioner used in this study provided excellent repeatability and reproducibility in ligamentous laxity assessment during RATKA, highlighting the potential benefits of incorporating robotics in TKA procedures.

Registry Data Show Complication Rates and Cost in Revision Hip Arthroplasty.

BACKGROUND: Revision total hip arthroplaty (rTHA) places a burden on patients, surgeons, and health care systems because outcomes and costs are less predictable than primary THA. The purpose of this study was to define indications and treatments for rTHA, quantify risk for readmissions, and evaluate the economic impacts of rTHA in a hospital system. METHODS: The arthroplasty database of a hospital system was queried to generate a retrospective cohort of 793 rTHA procedures, performed on 518 patients, from 2017 to 2019 at 27 hospitals. Surgeons performed chart reviews to classify indication and revision procedure. Demographics, lengths of stay, discharge dispositions, and readmission data were collected. Analyses of direct costs were performed and categorized by revision type. RESULTS: Totally, 46.3% of patients presented for infection. Patients presenting for infection were 5.6 times more likely to have repeat rTHA than aseptic patients. Septic cases (4.3 days) had longer length of stay than aseptic ones (2.4) (P < .0001). However, 31% of patients discharged to a skilled nursing facility. Direct costs were greatest for a two-stage exchange ($37,642) and lowest for liner revision ($8,979). Septic revisions ($17,696) cost more than aseptic revisions ($11,204) (P < .0001). The 90-day readmission rate was 21.8%. Septic revisions had more readmissions (13.5%) than aseptic revisions (8.3%). CONCLUSIONS: Hip revisions, especially for infection, have an increased risk profile and create a major economic impact on hospital systems. Surgeons may use these data to counsel patients on risks of rTHA and advocate for improved reimbursement for the care of revision patients.

The Economic Impact of Lower Extremity Periprosthetic Fractures in a Large Hospital System.

BACKGROUND: Periprosthetic fractures (PPFs) place a burden on hospital systems. They occur in older patients with medical comorbidities, as unplanned events requiring technically complex surgeries with expensive implants. The purpose of this study was to describe this patient population and evaluate the economic impact of PPFs on a hospital system. METHODS: We conducted a retrospective study of PPFs of the hip and knee between 2018 and 2019. Demographics, length of stay (LOS), and discharge disposition were collected. We performed chart and radiographic reviews to determine the fracture classification and type of treatment performed. An analysis of direct inpatient costs was performed and categorized by a fracture type. RESULTS: We identified 213 periprosthetic hip and 151 periprosthetic knee fractures. The mean age of hip patients was 77 years, and 71% were female. The average surgery time was 194 minutes, LOS was 5.01 days, and 71% were discharged to a skilled nursing facility (SNF). The mean age of knee patients was 76 years, and 79% were female. The average surgery time was 174 minutes, LOS was 5.12 days, and 70% were discharged to a SNF. The median direct cost of hip fractures was $17,108, with Vancouver B2 and B3 costing significantly more at $19,987 and $23,935, respectively (P value <.0001). The median direct cost of knee fractures was $13,713. Type 3 distal femur fractures cost significantly more at $37,445 (P value <.0001). CONCLUSION: PPFs create a significant economic impact on hospital systems. We stratified the costs of treatment based on the fracture type. Significantly higher costs are associated with injuries requiring revision implants.