- Prone and flexed: A radiolucent bolster or Wilson frame should be considered if fluoroscopy is to be used. A Wilson frame helps decrease lumbar lordosis and opens up the interlaminar space, facilitating the diskectomy and possibly reducing the amount of bone removed for exposure.
- Attention to pressure points: For all patients, careful pressure point positioning is critical. Younger patients, particularly preteens and younger, are more susceptible to pressure sores than adults. Special care must be taken to prevent venous restriction around the face and chin, which can be caused by some open-face pillows designed for prone positioning, as this may lead to skin breakdown and sloughing. The arms are supported and cradled by arm boards and foam, with particular attention to the course of the ulnar nerve around the lateral epicondyle of the elbow to avoid neuropathy. The elbows should not be flexed more than 90 degrees; likewise, the shoulders should not be abducted greater than 90 degrees to avoid pathological stretching of the brachial plexus.In more obese patients, the abdomen should hang freely to avoid increased abdominal pressure and thus prevent increased venous pressures that may contribute to more intraoperative bleeding. All pressure points, including the knees, should be padded to avoid pressure ulcers. The legs should be elevated above the level of the heart to encourage venous return.
- DVT prophylaxis: For older patients (> 12 years at the authors’ institution), mechanical DVT prophylaxis should be initiated.
While spine surgery in children uses many of the same techniques as in adults, there are important differences to bear in mind:
- Tissue consistency differs from adults: In young infants, secondary ossification centers may not be ossified, and aggressive use of Bovie electrocautery may traverse the cartilaginous bone and injure the neural structures or injure the ossification centers. Different from adult microdiskectomies, pediatric disc herniations tend to have greater viscoelastic content and are more difficult to remove. The herniation is often removed piecemeal and does not routinely express itself in large fragments.
- Midline versus paramedian approach using a small skin incision: A diskectomy can be performed via a midline “open” approach or with a small paramedian incision and tubular retractors. A fixed diameter retractor of 16 mm or less usually provides sufficient exposure and can be started 1.5– 2 cm from the midline. Fluoroscopy should be used to localize the rostro-caudal location of the incision and again used to localize appropriate placement of the retractor once docked. This normally yields an excellent cosmetic result, but it is a somewhat greater technical challenge than the slightly larger midline approach (30).
Diskectomy in Children
- Technique: After the laminotomy is complete and the ligamentum flavum is removed, the nerve root and thecal sac should be identified. The disk herniation usually can be palpated using a micro-Penfield 4 dissector. The nerve root and thecal sac can then be retracted medially, and bipolar electrocautery can be used to manage any epidural veins and veins over the annulus. The authors typically favor opening the annulus in a cruciate fashion and starting the initial incision parallel to the course of the nerve root. Down-pushing curettes can then be used to liberate any free fragments and complete the sequestrectomy with pituitary rongeurs. A dental dissector and nerve hook can be used to palpate over and under the nerve root, as well as medially under the thecal sac, to ensure that no free fragments are missed. Hemostasis can be facilitated by using thrombin-soaked material such as gelfoam or absorbable gelation powder (e.g., Surgifoam®).
- Positioning to open disk space and minimize bleeding: A radiolucent lordosis-reducing bolster, such as a Wilson frame, can aid significantly in opening up the interlaminar space and reducing intraoperative bleeding.
- Multilayer subcutaneous closure: A multilayer closure is performed, with details depending on the surgery, but use of an an absorbable suture is recommended for the deeper layers.
- Skin – can use absorbable stitch: For skin closure, the authors prefer a subcuticular absorbable suture followed by adhesive skin closure strips to reapproximate the epidermis. In the presence of an inadvertent durotomy, the authors routinely use a running resorbable suture to provide another watertight layer of closure.