December 2, 2010

3.5 mm Low Profile Cortical Screw

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When plates and screws are selected for fracture treatment, soft tissue and/or tendon irritation is a potential clinical problem. Screw head prominence can be especially problematic in subcutaneous locations such as the clavicle, the olecranon and the tibia. In situations where tendons sit above  the implant post fixation as observed in the distal radius, screw head prominence can also be an issue. In response to this clinical problem, a 3.5mm Low Profile Cortical Screw compatible with all Synthes 3.5mm plates has been developed. 

The 3.5 mm Low Profile Cortical Screw is intended for the fixation of fractures, osteotomies and nonunions of the clavicle, scapula, humerus, olecranon, radius, ulna, pelvis, femur, tibia, fibula, and calcaneous.

Design changes in the new screw consist of alterations to the head height, screw head outer diameter and geometry of the underside of the screw (Fig 1). These changes alter the location of the screws gauge line, allowing the 3.5 mm Low Profile Cortical Screw to be seated lower in a given plate hole (Fig 2). The new screws are available in both stainless steel and titanium and have a T15 StarDrive or Hex Drive recess.

Mechanical testing has shown that the 3.5 mm Low Profile Cortical Screw demonstrates failure torque, bending strength, and driving torque mechanically comparable to that of standard 3.5 mm cortex screws.

The new screw is an additional treatment option for surgeons with concerns about soft tissue and/or tendon irritation when using plate and screw fixation. It also addresses the clinical need to prevent or minimize additional surgical procedures to remove implants that become too uncomfortable or pose a health risk for the patient.

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Fig 1 Comparison of screw geometry of 3.5 mm Low Profile Cortical Screws and standard 3.5 mm cortex screws with Hex Drive (left) and StarDrive recess (right).
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Fig 2 Illustration of the difference in screw prominence when placing a 3.5 mm standard cortex screw (left) and a 3.5 mm Low Profile Cortical Screw (right).

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