Modular Sternal Cable System
Please note that in 2011, this product has been superseded by the Sternal Zipfix System.
With a minimum of 345,000, in the US alone, annually performed surgical procedures that involve splitting the sternum to enter the thoracic cavity and gain access to the heart and other key organs, the need for effective sternal closure poststernotomy is vital. For the last few decades, surgeons have relied on stainless steel wires as their preferred chosen method of sternal closure. Although the reported failure rate of this technique is low (25%), many patients still experience pain, clicking, and other problems associated with nonunions that go untreated. The sternum is a unique bone located in an environment of constant motion. The thoracic cavity is highly vascularized, but a common practice of open-heart procedures is to remove one of the key blood supplies to the sternum for the heart. The bone is mostly cancellous with a very thin cortical shell, and its quality is often compromised, as many heart patients have other serious comorbidities such as:
Chronic obstructive pulmonary disease (COPD)
Obesity
Diabetes
Previous steroid therapy
Osteoporosis
Problems with infection and failed closures have to be taken seriously, especially given the proximity to the heart. The need for an improved closure device has been recognized for many years and several products have attempted to solve this problem. For various reasons, none of these products have been able to obtain significant market share from the standard of care. The new Modular Sternal Cable System has been developed to address these needs. It consists of three basic implant components, which can be used alone or in combination, based on the surgeons preference and on patient condition.
Stainless Steel Cable
The principal component is a flexible stainless steel cable with a diameter of 1 x 1 mm. Contrary to standard wire, it has great strength, high flexibility, and a large surface area to allow for greater contact between bone and implant. Therefore the risk of pulling through bone is reduced. Each cable is supplied with a crimp fitting, which slides over the end of the cable and is crimped to maintain the tension in the cable. It can be used as a stand-alone solution for parasternal closure.
Cannulated Screw
For transsternal application of the cable, a blunt-tipped, self-tapping, stainless steel cannulated screw has been developed. The screw will be available in a variety of lengths at 1.0 mm increments for bicortical placement in the sternum with a minimum amount of protrusion through the posterior table. The screws serve as channels for the cable to pass through the sternum. This offers additional reinforcement instead of direct contact to the bone, therefore preventing it from damage. Reconstruction Plates Another component of the system is a series of stainless steel reconstruction plates. These plates are indicated for primary as well as secondary closures, for patients with limited sternum quality, and for secondary reconstruction of sternums that have fallen apart after initial surgery. The plates are fixed to the sternum with cannulated screws to reunite the hemi-sternums, which also serve as stress distributors. Depending on the surgeons preferred technique the cable is then applied through the cannulated screws and/or around the sternum and/or through the transverse holes in the plates to join and secure the two sternal halves.
Reconstruction Plates
Another component of the system is a series of stainless steel reconstruction plates. These plates are indicated for primary as well as secondary closures, for patients with limited sternum quality, and for secondary reconstruction of sternums that have fallen apart after initial surgery. The plates are fixed to the sternum with cannulated screws to reunite the hemi-sternums, which also serve as stress distributors. Depending on the surgeons preferred technique the cable is then applied through the cannulated screws and/or around the sternum and/or through the transverse holes in the plates to join and secure the two sternal halves.
Instruments
In addition to the implants in the set, a selection of instruments is offered, such as an instrument to tension, crimp, and cut the stainless steel cable. It is recommended to suture the cable directly through the sternum using the attached needle. Instrumentation to perforate the bone and facilitate cable passage when using cannulated screws is also available. Plate benders, plate cutters, depth gauges, screwdrivers and forceps are included in the system to facilitate installation of the implants. The screwdrivers have adjustable spade-bit tips that provide self-drilling functionality to the blunt-tip screws.
Closure of the sternum with cable.
Case images provided by Dr J Huh, Baylor College of Medicine, Texas Medical Center, USA.
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