Pull-out forces of headless compression screws in variations of synthetic bone models imitating different types of scaphoid fractures in good bone quality.

Screw osteosynthesis using headless compression screws has become the accepted gold standard for the surgical treatment of scaphoid fractures. Optimal screw specifications remain controversially discussed. We aimed to investigate the influence of bone model composition on screw stability tests using headless compression screws in different scaphoid fracture models.

Wrist movements induce torque and lever force in the scaphoid: an ex vivo study.

Purpose: We hypothesised that intercarpal K-wire fixation of adjacent carpal bones would reduce torque and lever force within a fractured scaphoid bone.

Methods: In eight cadaver wrists, a scaphoid osteotomy was stabilised using a locking nail, which also functioned as a sensor to measure isometric torque and lever forces between the fragments. The wrist was moved through 80% of full range of motion (ROM) to generate torque and force within the scaphoid.

Rotational Stability of Scaphoid Osteosyntheses: An In Vitro Comparison of Small Fragment Cannulated Screws to Novel Bone Screw Sets.

Background: The current standard of care for operative repair of scaphoid fractures involves reduction and internal fixation with a single headless compression screw. However, a compression screw in isolation does not necessarily control rotational stability at a fracture or nonunion site. The single screw provides rotational control through friction and bone interdigitation from compression at the fracture site.

In vitro experimental investigation of the forces and torque acting on the scaphoid during light grasp.

The aim of this study was to measure the magnitude and direction of forces and torque within osteotomized scaphoids within cadaveric wrists during grasping movement of the hand. The mechanical contributions of clinically relevant individual wrist-crossing tendon groups were investigated. Wrists of eight forearms were immobilized in the sagittal, transverse, and coronal plane on a fixation device with unhindered axial gliding.

A finite element analysis of two novel screw designs for scaphoid waist fractures.

The scaphoid is the most often fractured carpal bone. Scaphoid fracture repair with a headless compression screw allows for early functional recovery. The rotational stability of a single screw may be limited, having a potential negative impact on the healing process.

Finite element based estimation of contact areas and pressures of the human scaphoid in various functional positions of the hand.

The scaphoid is the most frequently fractured carpal bone. When investigating fixation stability, which may influence healing, knowledge of forces and moments acting on the scaphoid is essential. The aim of this study was to evaluate cartilage contact forces acting on the intact scaphoid in various functional wrist positions using finite element modeling.