Since Smith-Robinson, Derrymaker and Cloward published in the middle fifties their works (which they carried out simultaneously but independently) describing their respective surgical methods to execute the intersomatic arthrodesis of the cervical segment, very few technical variations have been brought about over the last 30 years, which was undoubtedly due to the obvious advantages of their methods over former techniques: their relatively easy execution, the few risks involved and the excellent results obtained.
Considering that the technique by Cloward (Anterior Intersomatic Arthrodesis with Cylindrical Graft) is the most widely used, not only at out Hospital but also at a large number of traumatology and neurosurgery services all over the world, we started a clinical and experimental work on the basis of our own experience with this technique, which covers the management of nearly 300 patients operated over the last eight years. In this sense, a series of changes was introduced affecting both the graft and some of the elements of Cloward's basic instruments, which changes permit minimization or elimination of a considerable number of intraoperatory and postsurgical complications which are frequently mentioned in the medical literature.
Our contribution to this surgical technique is summarized in two main points:
(a) the substitution of the plain cylindrical graft to be implanted in the corresponding intersomatic space, by a graft provided with a thread or coil, and
(b) the design of two instruments required to carry out the helicoidal insertion of the graft.
The technical procedure is schematically described as follows: after obtaining the graft (either by autologous extraction of the patient's own iliac crest or by the use of either a homologous graft or a kielsurgibone heterologous graft) a coil is threaded intrasurgically on the graft with a small lathe designed ad-hoc and previously sterilized, which permits the execution of the thread in a very easy and quick manner, with grooves which can be made as deep as required. In the case of heterologous grafts, the coil should preferably be threaded during the process of obtaining the graft.
The resulting helicoidal graft is kept in highly sterilized condition while the anterior side of the vertebral cervical bodies is being prepared following Cloward's standard technique.
After the cylindrical bed as been drilled in the corresponding intervertebral space, the graft is helicoidally inserted with the instruments specially designed for the purpose.
In order to facilitate the comprehension of all explanations, two sheets with drawings are attached to this descriptive memorandum, illustrating two examples of applications, wherein: