Composite Biosynthetic Graft for Repair of Long-Segment Tracheal Stenosis: A Pilot In Vivo and In Vitro Feasibility Study.

Pediatric patients who undergo surgery for long-segment congenital tracheal stenosis (LSCTS) have suboptimal outcomes and postsurgical complications. To address this, we propose a biosynthetic graft comprising (1) a porcine small intestinal submucosa extracellular matrix (SIS-ECM) patch for tracheal repair, and (2) a resorbable polymeric exostent for biomechanical support. The SIS-ECM patch was evaluated in vivo in an ovine trachea model over an 8 month period. Concurrently, the biosynthetic graft was evaluated in a benchtop lamb trachea model for biomechanical stability. In vivo results show that SIS-ECM performs better than bovine pericardium (control) by preventing granulation tissue/restenosis, restoring tracheal architecture, blood vessels, matrix components, pseudostratified columnar and stratified epithelium, ciliary structures, mucin production, and goblet cells. In vitro tests show that the biosynthetic graft can provide the desired axial and flexural stability, and biomechanical function approaching that of native trachea. These results encourage future studies to evaluate safety and efficacy, including biomechanics and collapse risk, biodegradation, and in vivo response enabling a stable long-term tracheal repair option for pediatric patients with LSCTS and other tracheal defects.

Impacts of Robotic Compliance and Bone Bending on Simulated in vivo Knee Kinematics.

Robotic testing offers researchers the opportunity to quantify native tissue loads for the structures of the knee joint during activities of daily living. These loads may then be translated into design requirements for future treatments and procedures to combat the early onset of knee degeneration following an injury. However, high knee loads during testing have the potential to deflect a robotic end effector and cause inaccuracies in the applied kinematics. Furthermore, bone bending could also induce kinematic change. This study aimed to quantify the effects of robotic compliance and bone bending on the accuracy of simulated in vivo kinematics in a KUKA KRC210 serial robotic system. Six (6) human cadaver knees were subjected to cyclic human gait motion while 6 DOF forces and torques were recorded at the joint. A Vicon T-Series camera system was used to independently record the applied kinematics. Periods of highest kinematic deviation occurred during instances of low joint loading, suggesting negligible levels of forced deflection for simulations of moderate levels of activity while results of this small study indicate that high physiologic loading poses low risk of deviation from target kinematics, further testing is necessary to confirm.