After a midline 6- to 8-cm-long skin incision is made, centered on the affected disk space, a curvilinear fascial incision is made, and the paraspinal muscles are retracted laterally up to the transverse processes. For this purpose, a gentle dissection laterally to the articular facets is achieved, using only bipolar coagulation in order to minimize bleeding. As a rule this maneuver requires tilting of the operating table towards the surgeon, in order to optimize the illumination and visualization of the anatomical structures to be dissected and exposed. The paraspinal muscles are retracted by using a Finochietto retractor with one hook-like blade held on the interspinous process at the midline and an extra-long two-valve (3-cm-large) retractor spreading the muscles away from the intertransversarii space. Once the superior and inferior transverse processes are exposed and the intertransversarii ligament is visualized, the operative microscope is brought into the surgical field. A “limited” drilling is performed between the superior transverse process and the isthmus. The exposure and enlargement of the outer portion of the neural foramen is allowed by the detachment of the intertransversarii ligament from the drilled transverse process in a medial-to-lateral direction, done by using a Kerrison punch. At this step, the operating table is tilted away from the surgeon and the angle of the operating microscope is changed accordingly, in order to obtain the best view of the nerve root and of the underlying ELDH. The ruptured disk is usually seen superior and medial to the nerve root. Microdissection is carefully performed, using low-power bipolar coagulation, fine suckers, and microdissectors, in order to minimize both surgical trauma and bleeding. Depending on the size and the actual location of the ELDH, the nerve root is retracted by using an angled microretractor and the fragment is removed (Fig. 3). The disk’s space is entered and emptied as much as necessary. At the end of the procedure, the intervertebral foramen is explored with a long 90° instrument, in order to check for adequate decompression of the nerve root. Careful hemostasis is achieved and the wound is carefully irrigated and closed in layers. In cases where preoperative diagnostic tests could indicate interlaminar exploration, and/or if the foraminal exploration could suggest that decompression was not adequate, a standard interlaminar exposure is made and the affected nerve root is exposed at its exit from the dural sac. In such cases, drilling of the medial part of the facet is minimized as much as possible in order to prevent the risk of postoperative instability. Approximately one-sixth of the present patient cohort required interlaminar exploration also. In those patients in whom disk rupture was also intraspinal, laminotomy was performed in the same session and fragments were removed from both sides of the neural foramen. For L5-S1 herniations we used basically the same technique, which, however, as a rule requires a certain amount of drilling of the lateral portion of the sacrum, which varies from case to case.

The patients were allowed to stand as soon as they were discharged from the recovery room, on average 6–8 h after the end of the surgical procedure. No immobilization vest was required and the patients were asked to limit only some of their usual activities (for example, lifting weights) for 2 months only and then resume their usual activities, including sports, with the obvious exception of sporting activities requiring excessive stress load to the spine.