General
Indications
- Grade I/II spondylolisthesis with or without lumbar spinal stenosis
- Lytic listhesis
- Grade 1 and above
- Degen listhesis
- Grade 2 and above
- If grade 1 and not dynamic can do PLF
- Spondylolisthesis with foraminal stenosis
- Patients who require stabilization and direct decompression of the spinal canal or the ipsilateral foramen
- Previous discectomy with recurrent disc
- Spondylodiscitis not resolving with abx, back pain and leg pain
Contraindications
- Patients with severe osteoporosis
- Patients with infection/discitis/osteomyelitis
- Collapsed or fused disc space
- High grade Spondylolisthesis
Pros
- Direct decompression of the neural elements
- A unilateral minimally invasive approach can achieve a circumferential fusion and decompression
- High fusion rates and low rates of infection
- Minimal blood loss
- A short length of postoperative stay
- Earlier return to work
- Less postoperative pain
- Screws can be augmented with bone cement in osteoporotic patients
Cons
- Not indicated if significant lordosis restoration is required
Aim
- Decompress the nerve root
- Decompress the thecal sac
- Insert an interbody cage
- Stabilize the segment with percutaneous pedicle screw instrumentation.
Theatre set up and positioning
- Prone with lordosis of the lumbar spine
Skin marking
- Palpate and mark
- Spinous processes (Midline)
- Iliac crests bilaterally
- Xray and mark
- Cranial and caudal pedicles of the intended level horizontally and vertically.
- Incision line: 1–2 cm lateral to the lateral borders of the cranial and caudal pedicle line
Incision
- 4–5 cm skin incision at the incision line
- Same incision used for percutaneous pedicle screw insertion
- Dissect down to the fascia.
- A 2.5 cm fascial incision is made medial to the skin incision.
- so it is angled towards the spinous process
- Screw insertion
- Place artery 1 finger breath lateral to the 3 or 9 o'clock or the facet. in the craniocaudal plane mid-point of the facet.
- Incision made. Incision at the contralateral side can be separate for two levels or continuous for one level. At the ipsilateral (left) make a continuous incision to join the upper and lower screw.
- Place jamshidi to border of facet and hammer it medially. When pass the facet place the wire in. Push wire into vertebral body
- Get x-ray to check wire in body
Approach
- Insert the first dilator, angle slightly medially, and “feel” for the base of the spinous process and lamina.
- Use the first dilator to dissect the soft tissue off bone.
- After the first dilator has been positioned on the bone, verify that it is located at the correct level using fluoroscopy.
- Proceed with sequential dilation guided by the first dilator.
- Determine the required tube length and insert the final tubular retractor level to the skin.
- Secure the retractor to the table-mounted arm.
- Use the microscope for visualization. Alternatively, an exoscope or loupes and headlights may be used.
- Insert the microscope so that the surgeon can be positioned parallel to the spine. This position will help with orientation.
- Using the microscopic, muscles overlying the bony structures are cleaned and the following should be visualized
- Facet capsule
- Lateral and inferior edges of the cranial lamina,
- Medial border of the ipsilateral facet joint,
- Ipsilateral pars interarticularis
Note entry for s1
Decompression
- Resection of the inferior articular process
- Resect the inferior articular process using either a drill or an osteotome.
- The main bony surgical landmarks are:
- Inferior medial border of the lamina (A)
- Pars interarticularis (B)
- An L-shaped or curved course is taken from point A to point B.
- Use a large pituitary rongeur to harvest the inferior articular process. This bone can be used for fusion later on.
- Resection of the superior articular process
- Identify the superior wall of the caudal pedicle and then use a burr or an osteotome to disconnect and harvest the superior articular process.
- This bone can be used for fusion later on.
- Resection of the ligamentum flavum
- Release the ligamentum flavum from the underlying dura with a ball tip hook. Resect the ligamentum flavum from lateral to medial to expose the disc within the foramen.
- Undercutting of the midline.
Discectomy
- After removing the ligamentum flavum, the disc will be visible. The exiting nerve root passes under the remaining pars interarticularis at the cranial margin of the visible field, and the traversing nerve root may be visualized medially.
- Ensure that the disc material is freed from the dura using a ball tip hook.
- Open the disc using a box-shaped incision. Ensure all incisions are made from medial to lateral, away from the traversing nerve, and from superior to inferior, to avoid inadvertent injury of the exiting nerve root.
- Perform a piecemeal discectomy using pituitary rongeurs and curettes.
- Decorticate the endplates using a rasp.
- Completely remove the cartilage from the vertebral endplates.
- Insert a disc shaver into the disc space and rotate, progressively distracting the disc space. Remove the remaining disc material and continue using larger disc shavers until maximal distraction without endplate damage is achieved. A trial can be used to further confirm the optimal implant size.
- Pack morselized bone graft into the anterior portion of the discectomy space.
Structural implant
- A structural implant of appropriate size, filled with additional bone graft, is impacted into the discectomy space, aimed medially towards the anterior third of the disc.
- AP and lateral X-Rays to confirm the cage positioning
- For maximum lordosis cage should be positioned as anteriorly as possible.
Closure
- Hemostasis
- Bipolar and Flowseal
- Packing the tube with gauze for five minutes will usually allow coagulation to take place.
- The tube is slowly removed.
- Any muscular bleeding should be identified and cauterized.
- Topical steroids are not recommended so as not to interfere with the fusion process.
- Close Fascia and skin
- Local used
- 0.25% bupivaccine and dimorph as epidural
Post op plan
- Lumbar immobilization is typically not required for one-level procedures. For high-risk patients or multilevel fusion, lumbar immobilization is at the surgeon’s discretion
Complications
33% in total
Dural tear 10%
Screw malposition 0.35 to 12.7%
Cage migration or slip 2%
Nerve injury
Deep infection 3%
Nonunion 10%
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