Abstract
Introduction: In 1971, Cloward wrote that after anterior cervical surgery, dysphagia occurs in all patients and is due to pressure on the oesophagus by the retractors. Recent studies indicate that dysphagia occurs in 54% of patients at 1 month and 13.6 % at 2 years. Recurrent laryngeal nerve injury occurs in 15 – 23 % producing hoarseness in one third of these. The continuing frequency of these complications even in experienced hands suggests that a review of retractor design and consideration of new designs is worthwhile.
Methods: A Medline search of unlimited years in English using terms: retractors, surgical instruments, development and history was performed. Described retractors and their design principles were reviewed and a novel principle identified from which an anterior cervical device was developed and tested.
Results: The novel general principle states that superior retraction is achieved by combining fixation onto bone with variable rotation of the retractor blade. Bone stabilization within the wound provides optimal stability and mechanical advantage for retraction while variable rotation allows retraction or tissue relaxation. Excluding the ubiquitous handheld retractors which lack stability, 7 different designs of anterior cervical retractors have been described. Anecdotally self retaining retractors are the most commonly used, but to be stable they require equal bilateral tissue counterforce and tissues that do not stretch. They are thus doubly ill suited for the asymmetrical anterior approaches to the anterior cervical spine. In the new anterior cervical retractor a small internal frame is fixed to the spine using standard Caspar screws. The frame slides with distraction. Routine surgery including plating is carried out within the frame. The frame provides stable axes for the independently rotating medial and lateral retractor blades.
Discussion: In the spine intermittent relaxation of retraction has recently been shown to reduce muscle injury and pain after lumbar surgery. This is the first retractor system that can be released without sacrificing stability or exposure. Despite numerous authors implicating cervical retractors as a source of complications there are few investigations and no studies investigating different designs. Rather than accepting or denying common complications we should investigate even our most familiar tools.
Correspondence should be addressed to Dr Owen Williamson, Editorial Secretary, Spine Society of Australia, 25 Erin Street, Richmond, Victoria 3121, Australia.
