Cannulated Screw System CSS+
Michael Swords, Tim Schepers, Matthew Tomlinson, Andrew Sands
Fig 1: The comprehensive and color-coded portfolio offers various options formultiple locations and varying anatomy. Cannulated screws are commonly used by orthopedic surgeons for the fixation of multiple fracture patterns and bone reconstructions. The screw cannulation allows placement over a guidewire to facilitate better accuracy before drilling or screw insertion. The use of cannulated screws adopts the principles of interfragmentary screw fixation and aims to optimize screw position.
In December 2021 the AO Trauma Technical Commission approved the Next Generation Cannulated Screw System Plus (CSS+) which was designed and developed by the Foot and Ankle Expert Group in collaboration with the AO primary industrial partner, DePuy Synthes.
Ranging in diameter from 2.0–7.5 mm (with 0.5 mm diameter increments from 2.0– 4.5, and 1.0 mm increments from 5.5–7.5), the color-coded screws are available in titanium with short and long partial thread as well as fully threaded (Fig 1). All implants are available in sterile and non-sterile packaging. Color-coded washers are available for every screw size (Fig 2).
Fig 2: All screw sizes can be inserted with a compatible washer. The Next Generation Cannulated Screw CSS+ is indicated for use in bone reconstruction, osteotomy, arthrodesis, joint fusion, fracture repair, and fracture fixation of bones appropriate for the size of the device. Color-coded instrumentation corresponding to its color-coded screw promotes ease of use and implantation (Fig 3).
Fig 3: Color-coded instrumentation provides an enhanced user experience. Exampleshown: 1.4/2.7 mm drill guide for 3.5 and 4.0 mm screws. In response to a clinical need for improved cutting performance the new and patented cannulated screw tip reduces the axial load needed to advance the screw; thereby achieving a more precise insertion with less, or no need for, pre-drilling and tapping (Fig 4).
Fig 4: Innovative screw tip provides improved cutting performance and ease of insertion. The common problem of guidewire deflection was addressed with new cobalt chrome (CoCr) guidewires which provide a 29% higher bending stiffness compared with their stainless-steel counterparts. This ensures a straighter path and maintenance of the intended screw trajectory on insertion (Fig 5).
Fig5: CoCr Guidewire enhances the screw insertion process and maintainsalignment. Trocar fluted and threaded tip options are available depending onscrew size. The system is neatly divided into preconfigured sets—small, medium, and large. These sets house separate screw racks and instrument trays according to size that is designed to provide efficiency in the operating room supply sourcing (Fig 6):
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Small set: 2.0, 2.5, 3.0, 3.5, and 4.0 mm screws
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Medium set: 4.5 and 5.5 mm screws
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Large set: 6.5 and 7.5 mm screws
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Large trauma set: 6.5 and 7.5 mm screws and long instruments specific for trauma use
Fig 6: System configurations include screws and compatible instruments. Basic instruments in the sets are size appropriate and include guidewires, drill bits, drill guides, countersinks, measuring devices, screwdrivers with handles, and drive adaptor for power insertion. Additional instrumentation is provided for the medium set and large set trays which includes tissue protectors, guidewire sleeves, long drill bits, countersinks, screwdrivers, and guidewires. Three ergonomic screw handles are included in the set. Unique to the large trauma set (6.5 and 7.5 mm cannulated screws) is the inclusion of multiple and adjustable wire guides for accurate guide wire placement (Fig 7).
Fig 7: Multiple and adjustable wire guides are available as modular options for both the6.5 and 7.5 mm cannulated screws. Hazards and labeling
Due to varying countries’ legal and regulatory approval requirements, consult the appropriate local product labeling for approved intended use of the products described on this website. All devices on this website are approved by the AO Technical Commission. For logistical reasons, these devices may not be available in all countries worldwide at the date of publication.
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