New Screw System Improves on K-Wires in Scapholunate Instability

Acumed has issued a press release trumpeting its new so-called SLIC Screw System for wrist reconstruction, which it says offers surgeons a new adjunct to soft tissue repair or reconstruction as it holds the bones in their reduced state while soft tissue repair heals.


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

The damage to the ligaments allows abnormal 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 in order to promote healing of the soft tissues and restore normal function.

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 aid in the initial reduction of the scaphoid and lunate and the placement of the screw in the central portion of these two carpals, affording the soft tissue repair the best opportunity for successful healing.

The SLIC Screw differs from other approaches, such as K-wires and conventional screws, in two significant ways: It has a joint that allows rotation between the scaphoid and lunate and secondly 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 8-12 weeks post-operatively and many conventional screws are removed by four months post-operatively.

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 – 22mm, 25 mm and 28 mm – with the length variation in the scaphoid portion of the screw.

Physician/Inventor comments

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

Source: Acumed, Inc., PR Newswire

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