Dynamic Locking Screw (DLS)
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Design and benefits of the DLS The DLS represents a new generation of locking screws that allows the surgeon to control the rigidity of plating constructs. Pin-sleeve design The DLS system is based on the proven advantages of standard locking screws by eliminating tension on the bone and compression between plate and bone, while simultaneously retaining circulation and protecting the periosteum from potential damage. The DLS pin-sleeve design is a technical breakthrough that combines locking technology with dynamic motion; the threaded sleeve anchors the DLS in the bone while the pin locks the DLS with its standardized threaded head into Synthes locking plates (Fig 2). The interplay between the sleeve and the pin determines the amount of motion induced in the fracture gap, a particularly beneficial feature when bridging is the chosen method of fracture treatment.
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Fig 2a–b Dynamic Locking Screw (DLS).
Material The new material of the DLS system also brings invaluable benefits. Cobalt chromium molybdenum alloy (CoCrMo) ensures the mechanical stability of DLS, while encouraging less on-growth and facilitating screw removal, similar to stainless steel screws. The DLS is fully compatible with all of Synthes’ titanium and stainless steel locking plates, which enables the system to complement well-established surgical techniques. Features and Benefits The new DLS has a range of benefits including: • • • • • • •
Fig 3 DLS constructs increase plate-side fracture motion; osteosynthesis with and without axial load.
DLS constructs increase plate-side fracture motion (Fig 3) Pin-sleeve design allows the surgeon to adjust construct rigidity Motion is contained within the screw, which therefore does not change the plate-screw or screw-bone interface Compatible with LCP and VA-LCP systems Can be used with stainless steel or titanium plates (produced using CoCrMo) StarDrive Recess for better torque transmission Rounded tip minimizes soft irritation.
The DLS is available in two sizes, the small fragment screw (3.7 mm) and the large fragment screw (5.0 mm). Small fragment screws allow 0.2 mm of additional motion in all directions between pin and sleeve of the screw, and large fragment screws allow for an additional motion of 0.35 mm.