OPLL (Ossification of Posterior Longitudinal Ligament)

Tsuyama Classification (Based on Lateral X-ray/CT)

1. Continuous Type (27%): A long lesion extending over several vertebrae. Most difficult to treat.
2. Segmental Type (39%): Lesions located behind each vertebral body, not crossing the disc. (Safest for ACDF/Corpectomy as discs are clear).
3. Mixed Type (29%): Combination of above. Most common.
4. Localized Type (5%): Circumscribed lesion at disc level.

CT Signs of Dural Penetration

If present, anterior surgery has 100% risk of leak if resection attempted.

1. Double Layer Sign: Anterior rim of ossification separated from posterior rim by a radiolucent line.
2. C-Sign: Curved shape of the mass.

Laminoplasty (Preferred)

• Indication: Multilevel OPLL (C3-C7) with K-Line (+).
• Rationale: Expanding the canal posteriorly allows the cord to "drift back" away from the anterior OPLL mass.
• Technique: "Open Door" (Hirabayashi) or "French Door" (Kurokawa).
• Plate Fixation: Use mini-plates to keep the lamina open.
• Advantages: Preserves motion (vs fusion), lower complication rate than anterior.
• Risks: C5 palsy (tethering from drift back), Axial neck pain.

Step-by-Step (Double Door / French Door):

1. Positioning: Prone, Mayfield head clamp. Neck flexed slightly (military tuck).
2. Exposure: Midline approach. Subperiosteal dissection to the lateral masses. Preserve the Semispinalis Cervicis attachment to C2 (reduces post-op kyphosis/pain).
3. Spinous Process: Removed.
4. Troughs:
   • Midline Trough: Created through the junction of the lamina (roof). Full thickness cut.
   • Lateral Troughs: Created at the lamina-facet junction bilaterally. Thin the outer cortex but leave the inner cortex intact (Greenstick fracture).
5. Opening: The split lamina are opened like a book ("French Door") laterally.
6. Fixation: Ceramic spacers or mini-plates bridge the gap and hold the door open.
7. Closure: Deep closure over a drain.

Anterior Decompression (ACDF / Corpectomy)

• Indication: K-Line (-) (Kyphosis), or massive focal compression greater than 60%.
• Technique:
  • Radical Corpectomy of involved bodies.
  • Floating Island Method: If dura is ossified, DO NOT remove the last layer of OPLL. Thin it down with a diamond burr until it floats on the dura ("Floating Method"). This prevents CSF leak.
• Risks:
  • CSF Leak: Very high (up to 30%).
  • Construct Failure: Long strut grafts kick out. Need posterior supplemental fixation often.

Step-by-Step (Corpectomy):

1. Approach: Standard anterior Smith-Robinson. Extended to expose vertebral bodies.
2. Discectomy: Performed at the levels above and below the OPLL.
3. Corpectomy:
   • Leksell rongeurs remove the anterior vertebral body.
   • High speed burr creates a trough (15-20mm wide).
   • Lateral wall preserved to protect Vertebral Arteries.
4. OPLL Resection:
   • The ossified ligament is thinned with a diamond burr.
   • It is carefully detached from the lateral dural margins with a micro-curette.
   • Floating: If adherent, the thinned island is left.
5. Reconstruction:
   • Expandable cage or Fibula strut graft.
   • Anterior plating (locking screws).
   • If greater than 2 levels removed, add Posterior Instrumentation (360 fusion) to prevent graft kick-out.

Laminectomy + Fusion

• Indication: K-Line (-) where Anterior surgery is too dangerous (dural ossification).
• Technique: Wide laminectomy followed by instrumented fusion (Lateral mass / Pedicle screws).
• Goal: Force correction of kyphosis into lordosis to create space.
• Risks: High C5 palsy rate (aggressive shifting of cord).

Step-by-Step (Laminectomy + Fusion):

1. Exposure: Midline posterior approach to C3-C7. Expose out to lateral masses.
2. Instrumentation:
   • Lateral Mass Screws (C3-C6): Magerl or Roy-Camille technique. Start point 1mm medial to center of lateral mass. Drill 14mm, trajectory 25 deg lateral, 35 deg cephalad.
   • Pedicle Screws (C7/T1): Stronger fixation distally.
3. Laminectomy:
   • High speed burr to create bilateral troughs at the lamina-facet junction.
   • En-bloc removal of the posterior arch (lamina and spinous processes).
   • Ensure the cord is free.
4. Correction:
   • Rods are contoured into Lordosis.
   • Reduction and compression performed to restore cervical alignment.
   • This "pulls" the cord posteriorly away from the OPLL mass.
5. Fusion: Decorticate lateral masses, place bone graft (autograft/allograft).