Posterior Cervical Foraminotomy (Keyhole)

Indication. Symptomatic unilateral cervical radiculopathy — dermatomal pain, paraesthesia, myotomal weakness and a diminished reflex concordant with imaging — that has failed 6 to 12 weeks of conservative care (physiotherapy, NSAIDs, activity modification), where the compressive pathology is a soft posterolateral disc herniation or a foraminal (uncovertebral / Luschka) osteophyte sitting lateral to the cord. It is also the operation of choice for recurrent radiculopathy adjacent to a prior ACDF when the new compression is posterolateral and a repeat anterior approach is undesirable (scar, prior irradiation, tracheostomy), and for patients who specifically want a motion-preserving option. Relative indications favouring the posterior route: a young patient (under 50) with a soft lateral disc where decades of fusion-related adjacent-segment stress are a concern; prior anterior cervical surgery; or a contraindication to the anterior approach. Contraindications - Absolute — myelopathy from central canal stenosis or anterior cord compression: a keyhole decompresses only the lateral foramen and cannot address ventral cord compression.

• Absolute — significant cervical kyphosis: removing posterior tension-band elements worsens the kyphotic deformity.
• Absolute — segmental instability on dynamic films (more than 3.5 mm translation or more than 11 degrees angular motion).
• Absolute — pathology needing more than 50 percent facet resection: proceed to laminectomy with fusion or ACDF instead.
• Relative — central disc herniation (ACDF gives direct anterior decompression and disc-height restoration), bilateral radiculopathy, predominant axial neck pain without radiculopathy (consider facet injection / medial branch blocks first), marked obesity (thick posterior soft-tissue envelope limits the tubular corridor), or prior posterior cervical surgery with scar.

Why posterior and not anterior? From behind you reach the root by drilling the lamina-facet junction, decompressing the lateral foramen and extracting the posterolateral fragment — without violating the disc space, inserting a graft, or fusing the level. That preserves the facet, the disc and the motion segment, avoiding the adjacent-segment stress that fusion transfers above and below over 10 to 20 years and the graft, plate, dysphagia, dysphonia (recurrent laryngeal nerve) and pseudarthrosis risks of ACDF. Foraminotomy versus ACDF — the decision

Consent. Counsel specifically for nerve root injury (less than 1 percent permanent; transient neuropraxia 2 to 5 percent), spinal cord injury (rare but catastrophic), CSF leak / durotomy (1 to 3 percent), postoperative instability that could require a secondary fusion, recurrence (5 to 10 percent), infection (less than 1 percent), and postoperative posterior neck pain. Setup. Prone on a Jackson spinal table or Wilson frame, head in Mayfield three-point pin fixation or a padded skull clamp, neck in neutral or slight flexion (never extension — it closes the foramen). General endotracheal anaesthesia with the patient prone; intraoperative neuromonitoring (SSEP and MEP) is strongly recommended for real-time warning of root or cord compromise. Single-dose IV cefazolin 2 g at induction (redose beyond 4 hours). Confirm the level with lateral fluoroscopy and a radiopaque marker on the target spinous process before any incision — wrong-level surgery is catastrophic and preventable.

The goal is to drill a small 'keyhole' at the medial facet-lamina junction, widen the neural foramen, decompress the exiting nerve root, and remove any posterolateral disc fragment or foraminal osteophyte — while preserving more than half of the facet and performing no fusion. The exposure (open or tubular) is laid out as the first steps below; it is the heart of the operation. Surgical anatomy that governs every step - The cervical facet (lateral mass) is oriented 45 degrees to the sagittal plane and is small — about 10 to 12 mm wide at C5-6. This is precisely why removing more than half destabilises the segment.

• The cervical nerve root exits ABOVE its corresponding pedicle (the C6 root at C5-6) at every subaxial level, then angles infero-laterally through the foramen at about 45 degrees. (Thoracic and lumbar roots exit below the pedicle — the cervical rule is the exception.)
• Foramen boundaries: roof = superior pedicle, floor = inferior pedicle, anterior = uncovertebral (Luschka) joint and disc, posterior = facet and ligamentum flavum.
• The vertebral artery runs in the transverse foramen, lateral to the uncovertebral joint — at risk if bone removal drifts too far laterally past the lateral mass.
• The posterior epidural venous plexus is prominent in the lateral recess and bleeds readily — control it before manipulating the root.
• The ligamentum flavum forms the posterior boundary of the canal; its lateral edge is removed to expose the root and epidural space.

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Rehabilitation | Phase | Timing | Activity & immobilisation | Physiotherapy | |-------|--------|---------------------------|---------------| | Immediate | Day 0 to 1 | Hourly neuro observations for 6 hours, then 2 to 4 hourly; regular paracetamol and NSAIDs, short oral opioid course, muscle relaxant for spasm; sit out and walk day 0 or 1; no collar needed (soft collar optional for comfort); drain out at 24 to 48 hours when output is low | — | | Early recovery | Weeks 1 to 2 | Walk freely; nothing heavier than 5 kg, no repetitive neck extension or overhead activity for 4 weeks; driving at 2 to 3 weeks once pain is controlled, range of motion is adequate and the patient is off opioids | Gentle active cervical range of motion from week 1 to 2 | | Strengthening | Weeks 4 to 8 | Removable splint for heavy tasks only; staples or sutures out at 10 to 14 days | Progressive dynamic strengthening of cervical and scapular stabilisers, postural and proprioceptive work | | Return to full function | Weeks 8 to 12 | Graded return; full unrestricted activity including heavy lifting and contact sports by 12 weeks | Sport- or work-specific rehabilitation | Most patients return to office or sedentary work at 2 to 3 weeks, light manual work at 4 to 6 weeks, and heavy manual work or contact sports at 8 to 12 weeks. Review at 6 weeks (neurological exam, wound, radiculopathy resolution — flexion-extension films if stability is in question), 3 months (most are back to full activity; persistent weakness warrants nerve conduction studies and repeat MRI), and 12 months (assess for recurrence; counsel that recurrent radiculopathy occurs in 5 to 10 percent over 10 years). Complications

Why the operation works. The posterior keyhole decompresses the exiting root without touching the disc space, so the motion segment, the facet and the disc are preserved. This avoids the adjacent-segment stress that ACDF transfers above and below the fusion (10 to 25 percent symptomatic adjacent-segment disease at 10 years in most ACDF series) and the graft, plate, dysphagia, dysphonia and pseudarthrosis morbidity of an anterior fusion. The trade-off is that the operation cannot restore disc height or address an anterior osteophyte — persistent discogenic or facet-mediated axial pain after surgery suggests ACDF would have been more appropriate. Best pathology. A soft posterolateral disc herniation (a migrated nucleus pulposus fragment) is the most common and most favourable indication — easily delivered through the keyhole with pituitary forceps once the bone is opened. A hard foraminal (uncovertebral) osteophyte is acceptable but technically harder, often needs more bone removal, and is where facet over-resection most often threatens. Outcomes. In appropriately selected patients, posterior cervical foraminotomy delivers 85 to 97 percent good-to-excellent outcomes at short to medium term, with complete or near-complete arm-pain relief in 85 to 95 percent, motor recovery in 80 to 90 percent of those with preoperative weakness within 6 to 12 months, a median return to work of 2 to 6 weeks, and a reoperation rate of 5 to 10 percent at 5 to 10 years (chiefly for recurrent herniation). Adjacent-segment disease is not a concern, because no fusion is performed — the central long-term advantage over ACDF. C7-T1 — a level that needs extra care. The C8 root (exiting at C7-T1) supplies the intrinsic hand muscles, so an injury here has profound functional consequences; the T1 vertebral artery lies closer to the field than at higher subaxial levels; the thoracic laminae and facet orientation differ at this transitional level; and the corridor is narrower, making facet preservation technically more demanding. Key evidence. Herkowitz and colleagues (1990) showed comparable good-to-excellent outcomes between posterior foraminotomy and ACDF for unilateral soft-disc herniation, with shorter hospital stay and earlier return to work after the posterior route. Clarke and colleagues (2007) found that foraminotomy did not increase same-segment or adjacent-segment disease when more than 50 percent of the facet was preserved — the technical principle that anchors the whole operation. Fessler and Khoo (2002) established the minimally invasive tubular (microendoscopic) technique with short operative times, minimal blood loss and next-day discharge. Skovrlj and colleagues (2014), in a national database analysis, confirmed low perioperative morbidity and a low rate of secondary fusion after minimally invasive foraminotomy. Emami and colleagues (2022) found no clinically meaningful mid-term outcome difference between ACDF and minimally invasive foraminotomy for cervical radiculopathy, the foraminotomy cohort avoiding fusion-related morbidity. Longer-term durability data (Rao and colleagues, 2011; Wimberley and colleagues, 2013) support the posterior approach when facet integrity is maintained.