Posterior Spinal Instrumented Fusion – Surgical Steps

1. Preoperative Planning

• Review imaging (X-ray, CT, MRI) to map pedicle anatomy, curve/deformity magnitude, and select fusion levels ("stable vertebra to stable vertebra" unless pedicle screw instrumentation allows stopping short) - Campbell's Operative Orthopaedics, 15th Ed.
• CT with Hounsfield unit assessment can help evaluate bone quality (osteopenia/osteoporosis) and pedicle morphology, especially in adult deformity or revision cases.
• Neuromonitoring (SSEP/MEP, EMG) setup for cases involving deformity correction or neural risk.

2. Positioning and Approach

• Patient positioned prone on a spinal frame (e.g., Jackson table) with padding to protect pressure points, free the abdomen, and optimize lordosis/kyphosis as needed.
• Fluoroscopic or navigation registration for level localization.
• Midline posterior incision through skin, subcutaneous tissue, and lumbodorsal fascia.
• Subperiosteal dissection of paraspinal muscles off the spinous processes, laminae, facet joints, and transverse processes (or pars/lateral masses in the cervical/thoracic spine) out to the desired lateral extent, with meticulous hemostasis.

3. Decompression (if indicated)

• Laminectomy, laminotomy, foraminotomy, or facetectomy to decompress neural elements in cases with stenosis, disc herniation, or fracture with canal compromise. This step is skipped in purely deformity cases without neural compression.

4. Instrumentation - Screw/Anchor Placement

• Anchors are placed into stable vertebrae above and below (and within) the level(s) to be fused: pedicle screws (most common), lateral mass screws (cervical), hooks, or sublaminar wires depending on region and bone quality.
• Entry points are identified anatomically and confirmed with fluoroscopy, stimulation (EMG threshold testing), or navigation; pedicles are probed, tapped, and screws inserted freehand or image-guided.
• In curves below T8, pedicle screw stimulation can confirm safe placement (freehand technique is common but adjunct confirmation is used selectively) - Campbell's Operative Orthopaedics.

5. Rod Placement and Correction/Reduction

• Rods are contoured to the desired sagittal and coronal alignment and secured to the screw heads/hooks with set screws or locking caps.
• Correction maneuvers are applied as needed: rod rotation, in-situ bending, compression/distraction between segments, translation, or cantilever techniques to restore alignment, reduce deformity, or reduce a fracture/spondylolisthesis.
• Cross-links (transverse connectors) may be added for additional torsional stability, particularly in longer constructs.

6. Interbody Fusion (if performed concurrently)

• In techniques such as PLIF or TLIF, the disc is removed via a posterior/transforaminal window, endplates prepared, and an interbody cage packed with graft is inserted before or after screw/rod fixation to restore disc height and add anterior column support - HSS Spine; Spine-health.

7. Bone Grafting / Arthrodesis

• Posterolateral gutters, facet joints, and decorticated transverse processes/laminae are prepared (decortication) to bleeding bone.
• Autograft (local bone from decompression, or iliac crest), allograft, and/or bone graft substitutes/BMP are packed along the posterolateral elements to promote fusion - this is the biological step that actually "fuses" the segments, while the hardware provides mechanical stability until fusion matures - Columbia Neurosurgery; Campbell's Operative Orthopaedics.

8. Final Construct Check and Closure

• Intraoperative imaging (AP/lateral fluoroscopy or X-ray) confirms screw position, rod placement, alignment, and correction.
• Neuromonitoring signals are confirmed stable; a wake-up test may be used in select deformity cases.
• Layered closure over a drain if needed (fascia, subcutaneous tissue, skin).

9. Postoperative Management

• Similar whether or not instrumentation is used: early mobilization, bracing in select cases, activity restriction until radiographic fusion is confirmed on follow-up imaging over months.

Summary sequence