סמינר מחלקתי בזום - מסיימת תואר שני

Internal Mechanics of the Wrist in the Sagittal versus Dart Throwing Motion

Plane in Adult and Elder Models: Finite Element Analyses

Vered Mahpari, Masters Student

Under the supervision of Dr. Sigal Portnoy and Prof. Meital Zilberman

Most clinical treatments for an injured wrist such as distal radius fracture, concentrate on movement in the sagittal plane. The rotation of the proximal carpal bones is smaller while moving the wrist in a Dart Throwing Motion (DTM) than in other planes. This might prove advantageous during rehabilitation exercises that incorporate the DTM plane by reducing pain. However, the stresses between the Radius and the carpal bones in these two planes have not been compared and might differ between adult and elder individuals. This paper compares the contact stresses between the Radius and two carpal bones (the Scaphoid and the Lunate) between two wrist positions: extension and radial-extension (DTM) and between adult and elder models. A healthy wrist of a 40 year old female was scanned using Magnetic Resonance Imaging in two wrist positions (extension, radial-extension). The scans were transformed into three dimensional (3D) models and meshed using ScanIP (Simpleware Ltd., Exeter, UK) software. Finite Element Analyses in each position of the wrist were conducted for both adult and elder models (using MSC Nastran software, MSC Software Corporation, CA, USA), which differentiate by the mechanical properties of the ligaments. In the adult model, the average contact stresses between the distal Radius and the proximal carpal bones were higher in Extension (8.40MPa Radius-Scaphoid and 5.34MPa Radius-Lunate) compared to Radial-Extension (2.82MPa Radius-Scaphoid and 3.06MPa Radius-Lunate). In the elder model, the average contact stresses between the distal Radius and the proximal carpal bones were higher in Extension (8.45MPa Radius-Scaphoid and 5.12MPa Radius-Lunate) compared to Radial-Extension (0.97MPa Radius-Scaphoid and 4.14MPa Radius-Lunate). The lower stresses found in Radial-Extension position might be advantageous in wrist rehabilitation due to possible reduced pain. According to the four finite element analyses presented in this thesis, this conclusion is relevant to both adults and elder individuals.