Acumed Debuts Bone-Stabilization Device

Acumed has launched the Scapho-Lunate Inter Carpal (SLIC) Screw System, a new device for stabilizing the bones during the repair and healing of the scapho-lunate interosseous ligament.

The SLIC Screw System — a jointed screw and a targeting guide with accompanying instrumentation to place and insert the screw accurately — gives surgeons a new tool to help heal damaged ligaments. The SLIC Screw is designed to maintain the anatomical reduction (spacing) of the scaphoid and lunate while allowing some rotation between the carpals. A radiolucent targeting guide is provided to help reduce the scaphoid and lunate and place the screw in the central portion of these two carpals, maximizing healing opportunities.

Scapholunate instability occurs when the ligament connecting these two carpals and secondary stabilizing ligaments are damaged – either from being torn or stretched beyond their normal capacity.

The damage to the ligaments allows abnormal rotation and motion (kinematics) of the scaphoid and lunate, which can lead to wrist pain and eventually arthritic changes in the wrist. While the scaphoid and lunate bones themselves are not damaged, the rotation and gap between the two wrist bones increases, and this must be anatomically reduced to properly mend the soft tissues and restore normal function.

The SLIC Screw differs from other approaches such as K-wires and conventional screws in two significant ways, according to the company. First, the SLIC Screw has a joint that allows rotation between the scaphoid and lunate.

Second, the screw is designed to be removed in six to nine months, protecting the soft tissue repair and allowing more time for biological healing. By contrast, K-wires are typically removed eight to 12 weeks post-operatively and many conventional screws are removed by four months post-operatively.

K-wires and conventional screws are removed early to allow more motion at the wrist and prevent stiffness. However, they stick out of the patient’s skin at the wrist during healing; specifically, K-wires can cause infection, skin irritation, limited rotation of the wrist, and possible instability when they are removed.

“The new SLIC Screw System provides mechanical support while the soft tissue repair heals and matures,” said orthopaedic surgeon William B. Geissler, M.D. “Prolonged stabilization of the involved carpal bones eliminates the potential complications of temporary Kirschner wire fixation.”

SLIC Screw

The joint of the SLIC screw resides in the interval between the scaphoid and lunate and allows for an approximate 15 to 22 degree toggle angle range of rotation. The screws come in three sizes: 22 millimeter, 25 millimeter and 28 millimeter, with the length variation in the scaphoid portion of the screw. The screw’s scaphoid portion varies in length to allow the surgeon to place the back end of the screw close to the scaphoid bone surface, simplifying removal upon healing of the soft tissue.

SL Targeting Guide

The SL Targeting Guide sits on the outside of the wrist and accomplishes several functions. With the use of a joystick clip and temporary K-wires, it enables the surgeon to reduce the scaphoid and lunate bones back into position.

It allows the user to locate the screw trajectory accurately using fluoroscopy, locking the guide wire (for the screw) in one plane of motion while adjusting and locking it in the second plane. Further, the Targeting Guide helps accurately place the guide wire centrally through the bones from the lateral view. Once the guide wire is placed properly, the bones then can be drilled and the screw inserted.

Based in Hillsboro, Ore., Acumed develops orthopedic implants and surgical devices. The company was founded in 1988.