[Epiduroscopy with access via the sacral canal. Some constructional equipment requirements from the anatomic and biomechanical viewpoint].

To ensure optimal mechanical functioning of the vertebral column, intact symmetry of its bony and muscular elements is mandatory. With this in mind, the need to reduce the invasiveness of spinal surgery is even greater than that applying to surgery in general. To avoid bony or muscular damage during surgery, in particular in the case of the segments L4/L5 and L5/S1-which are particularly prone to intervertebral disc rupture-laser discotomy procedures, with introduction of instruments via the sacral canal during epiduroscopy are presently being developed. Preliminary experiments on human corpses have demonstrated the practicability of the technique, but specially designed instruments have yet to be developed for use in patients. In an attempt to define the conditions of important for the design of the instrument, we have carried out a morphometric analysis of 100 sacral bones (56 females; 44 males). The configuration of the sacral canal is described in quantitative terms, and the results used to determine the diameters and curvatures of the instruments needed for laser discotomy.