[Surgical approach in lumbar intervertebral disk displacement. Topographical principles and characteristics].

For the operative procedure in lumbar disc extrusion it is important to expose the prolapsed disc and sequestrum without disintegration of the musculature and branches of r. dorsalis nervi spinalis or provoking lesions in the spinal canal. A classification helps to determine exact description of localization of disc material in craniocaudal and mediolateral directions. It can be correlated with the interlaminar window as a structure seen in the operative procedure. A speculum helps to limit the exposure for an interlaminar as well as a lateral access, thus reaching the structures concerned in the spinal canal with minimal irritation of the surrounding tissues. For interlaminar access partial excision of the lig. flavum is sufficient. The extrusions in the foraminal region that can be exposed laterally from a medial skin incision, as well as from a paramedial are between m. multifidus and m. longissimus. In revision surgery, the upper laminar corner is advantageous for entering the spinal canal.