There are over ½ million total knee replacement (TKR) procedures performed each year in the United States and is projected to increase to over 3.48 million by 2030. Concurrent with the increase in TKR procedures is a trend of younger patients receiving knee implants (under the age of 65). These younger patients are known to have a 5% lower implant survival rate at 8 years post-op compared to older patients (65+ years), and they are also known to live more active lifestyles that place higher demands on the durability and functional performance of the TKR device. Conventional TKR designs increase articular conformity to increase stability, but these articular constraints decrease patient range of knee motion, often limiting key measures of femoral rollback, A/P motion, and deep knee flexion. Without this articular constraint however, many patients report TKR “instability” during activities such as walking and stair descent, which can significantly impede confidence of movement. Therefore, there is a need for a TKR system that can offer enhanced stability while also maintaining active ranges of motion. A novel knee arthroplasty system has been designed that uses synthetic ligament systems that can be surgically replaced, to provide ligamentous stability and natural motion to increase the functional performance of the implant. A computational anatomical model (AnyBody) was developed that incorporated ligaments into an existing Journey II TKR. Ligaments were modeled and given biomechanical properties from literature. Simulated A/P drawer tests and knee flexion were analyzed for 2,916 possible cruciate ligament location and length combinations to determine the effects on the A/P stability of the TKR. A physical model was then constructed, and the design was verified by performing 110 N A/P drawer tests under 710 N of simulated body weight.Introduction
Materials and Methods
There are over one-half million total knee replacement (TKR) procedures performed each year in the United States and is projected to increase to over 3.48 million by 2030. Concurrent with the increase in TKR procedures is a trend of younger patients receiving knee implants (under the age of 65). These younger patients are known to have a 5% lower implant survival rate at 8 years post-op compared to older patients (65+ years), and they are also known to live more active lifestyles that place higher demands on the durability and functional performance of the TKR device. Conventional TKR designs increase articular conformity to increase stability, but these articular constraints decrease patient range of knee motion, often limiting key measures of femoral rollback, A/P motion, and deep knee flexion. Without this articular constraint however, many patients report TKR “instability” during activities such as walking and stair descent, which can significantly impede confidence of movement. Therefore there is a need for a TKR system that can offer enhanced stability while also maintaining active ranges of motion. A novel knee arthroplasty system was designed that uses synthetic ligament systems that can be surgically replaced, to provide ligamentous stability and natural motion to increase the functional performance of the implant. Using an anatomical knee model from the AnyBody software, a computational model that incorporated ligaments into an existing Journey II TKR was developed. Using the software ligaments were modeled and given biomechanical properties developed from equations from literature. Simulated A/P drawer tests and knee flexion test were analyzed for 2,916 possible cruciate ligament location and length combinations to determine the effects on the A/P stability of the TKR. A physical model was constructed, and the design was verified by performing 110 N A/P drawer tests under 710 N of simulated body weight.Introduction
Materials and Methods
The accumulation of proteins and bacteria on implant surfaces is a critical concern in the biomedical field, especially with respect to the potential of biofilm formation on implant surfaces. Material surface wettability is often used as a predictor of potential colonization of specific bacterial strains. Surface roughness has also been shown to have a strong relationship with biofilm formation, as rougher surfaces tend to have a stronger affinity to harbor bacterial colonies. The modification of implant surfaces to impart a biofilm resistant layer can come at the expense of increasing surface roughness however, and it is therefore important to determine how the variables of wettability and roughness are affected by any new surface coating technologies. In the current work, a novel CoBlast (C) process that impregnates alumina (A) at 50 μm grit (5) or 90 μm grit (9) sizes, with the possible addition of polytetrafluoroethylene (P) onto titanium surfaces, combined with a plasma coating process called BioDep, that coats the surface with chitosan (X) with the possible addition of vancomycin (V), were evaluated for wettability and surface roughness to determine their potential as biofilm resistant treatments on implants. N=65 titanium alloy samples (n=5 for 13 sample modification types as described above and in the figure legends below) were analyzed for surface roughness and wettability. Following cleaning in ethanol, roughness testing (Ra, Rq, Rt and Rz, Wyko NT-2000 optical profilometer @ 28.7× magnification, FOV of 164×215 μm) at 5 different surface locations per specimen, and contact angle analysis was performed (2 μL water drops, KRUSS EasyDrop). Statistical differences between groups was determined using ANOVA.Introduction
Materials and Methods
