Cervical Laminoplasty (Open-Door and French-Door)

Surgical Indications

Absolute Indications

• Multilevel (greater than or equal to 3 levels) cervical spondylotic myelopathy (CSM) with preserved cervical lordosis (C2-C7 Cobb greater than 10 degrees)
• Ossification of the posterior longitudinal ligament (OPLL) with multilevel cord compression and lordosis preserved
• Minimal pre-existing axial neck pain (visual analogue scale less than 4/10) — patients with severe axial pain are better served by fusion
• Progressive myelopathy (Nurick grade 2 or higher, or mJOA less than 14) despite conservative management

Relative Indications

• Patients who wish to preserve cervical motion and avoid fusion-related adjacent segment disease
• OPLL with segmental or continuous type where anterior surgery would require extensive corpectomy
• Poor anterior approach candidates (prior anterior surgery, radiation, tracheostomy, high BMI)

Contraindications

Absolute:

• Cervical kyphosis or straight alignment (C2-C7 Cobb less than 10 degrees) — cord cannot drift posteriorly
• Severe axial neck pain (greater than 6/10) with facet arthropathy — laminoplasty does not address posterior column pain generators
• Single-level disease better treated by anterior cervical discectomy and fusion (ACDF) or disc arthroplasty

Relative:

• Prior posterior surgery with extensive scarring
• Active infection or tumour requiring resection rather than decompression
• Severe osteoporosis increasing hinge fracture risk

Evidence for Laminoplasty versus Alternatives

Laminoplasty versus Laminectomy and Fusion

• Laminoplasty preserves motion (average 30-50 percent retained) and avoids fusion-related complications (pseudoarthrosis 5-15 percent, adjacent segment disease)
• A 2017 meta-analysis (Lau) showed equivalent neurologic recovery between laminoplasty and laminectomy-fusion but significantly lower axial pain and better ROM preservation with laminoplasty
• Laminectomy alone without fusion leads to progressive kyphosis in 20-40 percent and is largely abandoned

Laminoplasty versus Anterior Surgery (ACDF or Corpectomy)

• For greater than or equal to 3 levels, posterior laminoplasty has lower dysphagia, recurrent laryngeal nerve injury, and adjacent segment disease risk
• Anterior surgery preferred when lordosis is lost, focal kyphosis present, or when greater than 50 percent canal compromise from large disc/OPLL requiring direct resection

Key Evidence Summary

Landmark Evidence

Posterior Cervical Anatomy Relevant to Laminoplasty

Bony Anatomy

• The cervical lamina forms the posterior arch of the spinal canal; thickness varies from 3-5 mm at C3-C6
• The lamina-lateral mass junction is the critical landmark for trough creation; the facet joint lies immediately lateral
• C7 lamina is the largest and thickest; C2 lamina is short and stout with the semispinalis cervicis inserting on its spinous process

Muscular Attachments — The Key to Lordosis Preservation

• Semispinalis cervicis: inserts on the C2 spinous process; provides the primary posterior tension band for head extension
• Multifidus: deep stabiliser inserting on C7 and upper thoracic spinous processes; critical for segmental stability
• Detachment of these muscles leads to loss of dynamic lordosis, facet overload, and progressive kyphosis in 20-40 percent of cases

Ligamentum Flavum and Dural Attachments

• The ligamentum flavum attaches to the lamina undersurface; it must be divided at the open trough to allow elevation
• Dentate ligaments tether the cord laterally; excessive posterior cord shift stretches C5 and C6 roots

Neural Anatomy

• The C5 root exits most horizontally with the shortest intradural length (approximately 10-12 mm); this anatomy explains its vulnerability to tethering during cord drift-back
• The cord occupies 50-70 percent of the canal in severe stenosis; canal expansion of 8-12 mm allows 2-4 mm posterior drift

Vascular Considerations

• The vertebral artery lies within the transverse foramen 1.5-2 cm lateral to the lateral mass; troughs must not extend into the foramen
• Epidural venous plexus is prominent; meticulous bipolar haemostasis prevents post-operative haematoma

Positioning and Preparation

Patient position: Prone on Jackson table or Mayfield head holder with slight reverse Trendelenburg (15-20 degrees) to reduce venous bleeding. Head in neutral or slight flexion to open the interlaminar spaces. Arms tucked, all pressure points padded. Intraoperative neuromonitoring (MEP, SSEP, free-running EMG) mandatory.

Anaesthesia: General endotracheal; avoid hypotension (MAP greater than 80 mmHg) to maintain cord perfusion. Cell saver available for anticipated blood loss of 200-400 mL.

Consent: Discuss C5 palsy (5-10 percent, most transient), axial neck pain (10-20 percent even with muscle preservation), hinge fracture, incomplete decompression, infection (less than 2 percent), and the need for possible revision fusion.

Open-Door Technique — Step-by-Step

Step 1: Exposure and Muscle Preservation

Midline skin incision from C2 to C7. Subperiosteal elevation strictly limited to C3-C6 laminae. Identify and preserve the semispinalis cervicis insertion on the C2 spinous process and multifidus on C7. The C2 and C7 spinous processes remain intact. Expose the lamina-lateral mass junction bilaterally from C3 to C6.

Step 2: Creating the Hinge and Open Troughs

Under loupe magnification or microscope, mark the troughs at the lamina-lateral mass junction. The hinge side (usually left for right-handed surgeon) is thinned with a high-speed burr to approximately 50 percent depth, creating a greenstick hinge. The open side is drilled completely through the lamina into the epidural space, then completed with a Kerrison rongeur, dividing the ligamentum flavum.

The open trough must reach the medial border of the lateral mass without entering the facet joint. The hinge trough is parallel and symmetric.

Step 3: Lamina Elevation and Canal Expansion

Gently elevate the opened laminae with a Penfield or lamina elevator in a controlled, gradual manner. Aim for 8-12 mm of opening at the open side. Confirm cord decompression with intraoperative ultrasound. Avoid sudden or excessive elevation that causes cord shift greater than 4 mm.

Step 4: Mini-Plate Fixation

Apply pre-contoured mini-plates (usually 8-12 mm length) spanning from the elevated lamina to the lateral mass. Fix with 5-7 mm lateral mass screws (trajectory 25-30 degrees lateral, 15 degrees cephalad) and 4-5 mm lamina screws. Typically two or three levels are plated; the remaining levels may be secured with sutures or left as floating hinges if stable.

Step 5: Closure and Haemostasis

Meticulous bipolar haemostasis of the epidural plexus. Layered closure with absorbable sutures to the preserved muscle fascia. No drain routinely required. Skin closure with subcuticular absorbable suture.

French-Door (Double-Door) Laminoplasty

The French-door technique splits the spinous processes in the midline and creates bilateral hinges at the lamina-lateral mass junctions. The two hemilaminae are elevated symmetrically, creating a wider central canal. Fixation options include:

• Central suture or bone-block spacer between the split spinous processes
• Bilateral mini-plates on each side
• Titanium spacers or hydroxyapatite blocks in the open gutters

Advantages: More symmetric canal expansion; potentially lower hinge fracture rate on any single side. Disadvantages: Longer operative time; risk of spinous process fracture; technically more demanding in OPLL with asymmetric compression.

Fixation Options Comparison

When to Choose Laminectomy and Fusion Instead

• Pre-operative kyphosis or C2-C7 Cobb less than 10 degrees
• Significant axial neck pain with facet arthropathy
• Need for correction of fixed deformity
• Revision surgery after failed laminoplasty
• Tumour or infection requiring stabilisation

Post-operative Protocol

Immediate (Day 0-3)

• Neurological monitoring every 2 hours for first 24 hours (C5 palsy risk peaks day 1-3)
• Cervical collar (soft) for comfort only — remove for gentle isometric exercises from day 1
• Early mobilisation out of bed day 1; no bed rest
• Analgesia: paracetamol, NSAIDs, gabapentin for neuropathic pain; opioids sparingly

Early Rehabilitation (Week 1-6)

• Isometric neck exercises from day 1 (flexion, extension, rotation against resistance)
• Gentle active range of motion from week 2
• No formal collar beyond 2 weeks — prolonged immobilisation increases stiffness and muscle atrophy
• Hand therapy for myelopathy-related dexterity deficits

Return to Function

• Driving: 4-6 weeks when neck rotation safe
• Light work: 6-8 weeks
• Heavy manual labour or contact sports: 3-6 months
• Full neurologic recovery assessment at 6 and 12 months

Complications — Incidence and Management

C5 Palsy (5-10 percent)

• Most present day 2-7 with deltoid and biceps weakness, often with sensory loss in C5 dermatome
• 80-90 percent resolve spontaneously within 6-12 months
• Management: physiotherapy, steroids if acute, EMG at 6 weeks; tendon transfer (e.g. levator scapulae to deltoid) for permanent deficit

Axial Neck Pain (10-20 percent even with muscle preservation)

• Usually improves by 3-6 months; chronic pain in 5-10 percent
• Management: physiotherapy, NSAIDs, trigger point injections; rarely requires fusion

Hinge Fracture (2-5 percent)

• Detected on post-op CT; may be asymptomatic or cause instability
• Management: observation if stable; revision plating or fusion if symptomatic or progressive kyphosis

Incomplete Decompression / Recurrent Myelopathy (3-8 percent)

• Causes: inadequate opening, hinge closure, progressive OPLL, adjacent segment stenosis
• Management: revision anterior surgery or posterior fusion depending on alignment and pathology

Infection and Wound Complications (less than 2 percent)

• Standard prophylaxis; treat with antibiotics and possible washout