Scaphoid Open Reduction Screw Fixation
The guiding principle for operative treatment of scaphoid fractures is an anatomic reduction and compression across the fracture. There have been many developments to simplify techniques and minimize destruction when fixing it. Passing a small wire from either the front or back of the scaphoid along its long axis, checking its position with the aim to be as center as possible within the bone and then threading a hollow screw over the wire has shown to be an effective method to heal the bone. The design of the screw adds to its compressive ability. The far threads on the screw have a larger pitch than the near threads, so that as the far end of the screw engages the far fragment, the screw moves a larger distance per rotation than in the near fragment, compressing the two fragments together. Another technique involves a staple across the fracture site. The staple provides compression as well minimizes destruction of the center of the scaphoid.
Scaphoid Fracture Fixation
Operative fixation of scaphoid fracture relies on compression across the fracture to stimulate healing. Depending on the nature of the fracture, the surgeon may make a surgical incision and dissection on either the front or back of the hand or possibly do the surgery through a hole just large enough for the screw, called percutaneous screw fixation. After x-rays are taken to ensure proper placement of hardware, the wound will be closed and the hand will likely be placed in a thumb spica splint, designed to immobilize the thumb and scaphoid while the bone heals.
The scaphoid is the most common carpal bone to be broken in the hand and often present as tenderness to the space in between the thumb and the index finger deemed the “anatomic snuffbox”. It articulates with four other bones in the hand and the radius, making it important for overall hand and wrist motion. Because of all the areas on the scaphoid dedicated to motion with other bones, the blood supply is tenuous and comes from the end of the bone in a retrograde fashion. This atypical blood supply pattern makes healing the bone after fracturing difficult. If the scaphoid is unable to heal, part of it dies, resulting in a condition called scaphoid non-union advanced collapse (SNAC wrist) which is a painfully debilitating cascade of osteoarthritis in the hand.
The MAX VPC™ Variable Pitch Compression Screw is a headless, fully threaded, cannulated screw. Without a head, the screw can maintain a low profile to avoid soft tissue irritation or impingement on other structures. The fully threaded variable pitch nature of the screw allows greater tactile feedback when inserting the screw. The screw intrinsically has a self-tapping design to create the grooves in which the threads will travel, eliminating the screw tapping step found in other screw designs. It is a cannulated screw, which allows easy placement of the screw over the top of previously placed smaller wire for accurate trajectories