1 – Patient Positioning › Top of page
2 – Marking the Entry Point › Top of page
A special localization device with two arms is used with the fluoroscopic image intensifier to determine the point of the skin incision. The target disc is centered on the monitor screen of the image intensifier. The localization device is placed in position and its position modified until the two arms are projected onto the disc.
The point of incision is marked on the skin and the direction of the operating light is adjusted to the direction of the approach i.e. to the orientation plane of the disc. This direction is a line of reference throughout the operation
In the first instance the technique will be described for a left L5-S1 hernia, then for different types of hernia.
The surgeon takes up a position on the side of the hernia.
3 – Technique for a left sided disc herniation › Top of page
The skin incision is made 5 mm from the midline, at the lateral edge of the spinous process.
It can sometimes be difficult to remove the obturator ; if this is the case, pushing in with the thumbs on the operating tube will separate it from the obturator so that the latter can be withdrawn easily.
It is essential for the rest of the procedure that soft tissue be removed from the end of the operating tube to expose the superior lamina and yellow ligament as clearly as possible. Muscle vessels are coagulated using the bipolar forceps.
The first step of the endoscopic stage of the procedure involves partial resection of the superior lamina to detach the yellow ligament. Resection is initiated at the medial part of the superior lamina and continues laterally. Once detached, the yellow ligament is resected using a Kerrison bone punch.
L: lamina / J: yellow ligament
In the next step, the external border of the dural sheath in the superior part of the operating field is exposed and a cotton swab can be slid into place. Resection of the lateral extension of the yellow ligament and the internal part of the underlying articular mass exposes the nerve root. This can be dissected.
*: nerve root / D : dural sac
The nerve root retractor is inserted into the spinal canal. A second cotton swab is slid downwards, aiding hemostasis and shifting the nerve medially. This allows the nerve root retractor to be removed and the mobility of the system to be recovered.
Any free fragments are removed and a partial nucleotomy is performed. The disc cavity is irrigated with isotonic solution under controlled inflow pressure. The disc cavity may be inspected by inserting the HOPKINS® telescope. The ENDOSPINE® operating tube is withdrawn and hemostasis of the muscle vessels can be completed.
4 – Topographic variations › Top of page
1 – Right Posterolateral Disc Herniation
For a right-sided lumbar disc hernia the surgeon is positioned to the right of the patient with a shelf to his left, above the feet of the patient, to support the cables. The technique is identical but difficulties may be encountered during partial resection of the superior lamina. This resection must be started from the medial part of the lamina making a notch there. From this notch the bone can easily be resected outwards. This is continued until the canal is open.
2 – Central Disc Herniation
N : N=nerve root / *=hernia / C=hook
In central disc hernias, the approach is from the side where the symptoms predominate.
In large medial hernias, it is impossible to expose the apex of the hernia. A hook may aid in extracting the hernia.
3 – Foraminal / Extraforaminal Disc Herniation
In foraminal and extraforaminal disc hernias, the target is no longer the disc but the foramen. On the fluoroscopic image intensifier screen, the two arms of the localization device must be brought in line with the superior third of the foramen, parallel to the disc.
The skin incision is likewise 5 mm from the midline but slightly more cranial. The muscles ares dissected laterally to expose the lateral limit of the isthmus.
The nerve root retractor, that is not useful in this type of hernia, may serve as a muscle retractor. For this purpose, it should be introduced prior to the operating tube and the curved part directed laterally, following the contour of the paravertebral muscles.
Bone resection begins with the inferior part, i.e. at the superior extremity of the articular mass.
Often a muscle artery bleeds and must be coagulated serveral times. Bone resection continues upwards until the foraminal ligament is elevated from the bone. Normally the nerve root is visible running around the pedicle. If this is not the case bone resection continues until arriving at the base of the pedicle to expose the nerve. The following step consists of separating the ligament from the root then resecting it with the Kerrison forceps.
* : hernia / N : nerve root and its ganglion
The nerve root is dissected, the hernia is exposed and removed.