Spinal Tuberculosis — Debridement and Fusion

Surgical Indications

Absolute Indications

• Progressive or severe neurological deficit (Frankel C or worse) despite adequate ATT — surgical decompression is urgent
• Neurological deterioration while on ATT — the most urgent surgical indication
• Failure of medical management: progression of deformity or increase in pain after 4-6 weeks of adequate ATT
• Severe kyphosis (Cobb angle greater than 40 degrees) at presentation or progressive kyphosis on treatment
• Instability: translational movement on dynamic radiographs or segmental collapse with loss of normal sagittal alignment
• Large abscess not resolving on ATT with significant thecal sac compression or causing dysphagia/airway compromise (cervical)

Relative Indications

• Moderate kyphosis (20-40 degrees) in children — risk of progression with growth; combined anterior-posterior surgery is recommended
• Multi-level disease (more than 2 contiguous vertebral bodies) — associated with instability and deformity progression
• Persistent severe pain attributed to mechanical instability despite adequate ATT
• Tissue diagnosis required — when imaging is atypical or malignancy cannot be excluded
• Late onset paraplegia (greater than 2 years after quiescent disease) — mechanical compression from internal kyphosis

Contraindications

Absolute:

• Active pulmonary TB with positive sputum — treat with ATT first until sputum conversion (usually 4-8 weeks) before elective spinal surgery. Urgent decompression for neurological deficit overrides this
• Multi-drug resistant (MDR) TB without effective drug regimen — surgery is extremely high risk for implant infection and non-union
• Poor nutritional status (albumin less than 25 g/L, severe cachexia) — correct nutrition before surgery
• Active miliary TB — prioritise medical treatment

Relative:

• Advanced age with multiple comorbidities
• Severe pulmonary compromise — thoracotomy may not be tolerated; consider costotransversectomy or posterior approach
• Irreversible complete paraplegia of more than 6 months duration (Frankel A) — surgical decompression rarely improves motor function; surgery is for deformity and pain only

Evidence for Non-Operative Treatment

Anti-Tubercular Chemotherapy (ATT)

ATT is the foundation of medical management for spinal tuberculosis. The standard regimen follows the same principles as pulmonary TB:

Standard short-course regimen:

• Intensive phase (2 months): four drugs — rifampicin (R), isoniazid (H), pyrazinamide (Z), ethambutol (E)
• Continuation phase (10 months): two drugs — rifampicin (R), isoniazid (H)
• Total duration: 12 months minimum; 12-18 months in the presence of extensive disease, neurological involvement, or after surgery

Why duration is longer than pulmonary TB (6 months): The vertebral body is a relatively poorly perfused site and has a higher organism burden. Drug penetration into caseous material and bone is variable. Relapse rates are higher with shorter courses (less than 9 months) in spinal TB.

Monitoring: Monthly clinical assessment (pain, neurology, weight, ESR/CRP). Radiographs at 3, 6, 12 months. MRI if neurological deterioration occurs or if response is unsatisfactory.

Outcome of Non-Operative Management

The Medical Research Council Working Party on Tuberculosis of the Spine conducted a landmark series of multi-centre randomised trials comparing ambulatory chemotherapy with surgical treatment:

Data from MRC Working Party trials on tuberculosis of the spine (multiple reports, 1973-1999).

Key conclusion: Chemotherapy alone is sufficient for patients without neurological deficit, without significant deformity (kyphosis less than 20 degrees), and with disease limited to one or two vertebral bodies. Surgical intervention improves kyphosis correction and provides more reliable neurological recovery in patients with deficit.

Evidence for Surgery

The Hong Kong Operation (Hodgson & Stock, 1956)

The landmark contribution of Hodgson and Stock at the University of Hong Kong was the recognition that:

1. The disease is primarily anterior (vertebral body and disc)
2. An anterior approach gives direct access to the pathology
3. Radical debridement followed by autogenous bone grafting achieves both disease clearance and mechanical reconstruction
4. The graft incorporates rapidly in a well-vascularised environment after debridement

Their original description: Transthoracic approach, resection of the affected vertebral body and adjacent discs back to healthy bleeding bone, and placement of a tricortical iliac crest autograft under compression. No posterior instrumentation was used.

Long-term outcomes (Upadhyay, 1996): At a mean follow-up of 15 years, 94% of patients had solid bony fusion. Kyphosis correction achieved at surgery was partially lost during graft incorporation (mean loss of 6 degrees). Late neurological deterioration was rare (less than 2%).

Modern Surgical Approach: Anterior Debridement with Posterior Instrumentation

The addition of posterior pedicle screw instrumentation to the Hong Kong operation has significantly improved kyphosis correction and maintenance:

• Immediate rigid stabilisation allows early mobilisation without external bracing
• The posterior construct offloads the anterior graft, reducing subsidence and graft fracture
• Kyphosis correction is improved (mean 15-20 degrees correction vs 5-10 degrees with anterior alone)
• Fusion rates are higher (greater than 95% in modern series)

Implication for practice: Combined anterior-posterior surgery is the modern standard for patients with:

• Kyphosis greater than 30 degrees
• Involvement of more than 2 vertebral bodies
• Neurological deficit
• Significant instability

Anterior alone is reserved for single-level disease with good bone stock, no significant kyphosis, and no neurological compromise. Posterior alone has a limited role — mainly for disease confined to the posterior elements or when an anterior approach is contraindicated.

Key Evidence

The Three-Column Spine in Pott Disease

Anterior Column (Anterior Longitudinal Ligament + Anterior Two-Thirds of the Vertebral Body)

• Primary site of disease — the infection typically begins in the anterior vertebral body (paradiscal), then spreads through the intervertebral disc to the adjacent body
• The anterior longitudinal ligament (ALL) is usually stripped off the vertebral bodies by the developing abscess but often remains intact as a sleeve
• The ALL can be preserved at surgery and closed over the graft to contain the reconstruction

Middle Column (Posterior One-Third of the Vertebral Body + Posterior Longitudinal Ligament)

• Key to neurological status — retropulsion of the posterior vertebral body wall or disc into the spinal canal compresses the thecal sac
• The posterior longitudinal ligament (PLL) may be elevated by the abscess or caseous material — it can be a barrier to cord compression or a source of residual compression if not addressed
• At surgery, the PLL should be opened to inspect the canal and ensure complete decompression

Posterior Column (Pedicles + Laminae + Facet Joints + Spinous Process + Ligamentum Flavum)

• Rarely involved in pure Pott disease — the posterior elements are typically spared
• Involvement of the posterior elements suggests either very advanced disease or alternative pathology (pyogenic infection, malignancy)
• The posterior column provides the fixation points (pedicle screws) for the stabilisation construct
• The facet joints at the affected level are typically preserved — they can be used for posterior stabilisation

Pattern of Spread

The infection in spinal tuberculosis follows a characteristic pattern:

1. Paradiscal type (most common, ~90%): Begins in the anterior vertebral body adjacent to the disc. Spreads across the disc space to the adjacent vertebral body. The disc is destroyed early.
2. Central type (~5%): Begins in the centre of the vertebral body. May produce vertebral collapse (vertebra plana) without significant disc space involvement. Can mimic malignancy.
3. Anterior type (~3%): Subperiosteal spread beneath the ALL without significant vertebral body destruction. Multiple levels may be involved without disc space narrowing.
4. Posterior type (~2%): Isolated involvement of the posterior elements. Rare. Can mimic a posterior element tumour or pyogenic infection.

Abscess Anatomy and Spread

Paravertebral Abscess in the Thoracic Spine

• The abscess lifts the parietal pleura and paravertebral fascia — appears as a fusiform paravertebral soft tissue shadow on chest radiograph
• Can track up and down beneath the ALL for several levels, producing the characteristic 'sausage shadow'
• Spontaneous drainage: can erode through the pleura into the pleural space (empyema), through the skin (sinus), or through the diaphragm into the retroperitoneum (psoas abscess)

Psoas Abscess in the Lumbar Spine

• Pus tracks along the psoas muscle sheath from the lumbar vertebral level
• Can present as a groin mass, hip flexion deformity, or referred pain to the hip
• Danger: The psoas muscle is intimately related to the kidney, ureter, kidney vessels, and lumbar plexus. The ureter lies on the anterior surface of the psoas and can be injured during drainage.

Cold Abscess Characteristics

• 'Cold' = no heat or erythema — distinct from pyogenic abscess
• Contains caseous material (thick, cheesy, necrotic debris), liquefied pus, and granulation tissue
• The wall of the abscess is composed of fibrous tissue, granulation, and epithelioid cells
• Clinical importance: The abscess may be very large (containing 100-500 mL of pus) but cause surprisingly few systemic symptoms

Anterior Surgical Approach Anatomy

Transthoracic Approach (Thoracic Spine, T2-T10)

Level selection:

• Upper thoracic (T2-T5): A right-sided thoracotomy through the 3rd or 4th intercostal space. The scapula must be retracted (or the approach is transpleural without scapular mobilisation for T2-T4).
• Mid-thoracic (T5-T9): Right-sided thoracotomy through the 5th or 6th intercostal space. Right-sided is preferred because the aorta is on the left and the segmental vessels are easier to control from the right.
• Lower thoracic (T9-T10): Left-sided thoracotomy through the 7th or 8th intercostal space may be preferred for access to the thoracolumbar junction.

Structures at risk during approach:

• Intercostal neurovascular bundle at the inferior border of each rib — stay on the superior border of the rib when entering the chest
• Lung (retracted medially with wet laparotomy pads)
• Azygos vein (right side), hemiazygos and aorta (left side)
• Thoracic duct — crosses from right to left at T4-T6 level; injury causes chylothorax
• Sympathetic chain — runs along the heads of the ribs; injury causes Horner syndrome (upper thoracic) or post-sympathectomy syndrome (lower thoracic)
• Artery of Adamkiewicz (great anterior radicular artery) — enters the spinal canal on the LEFT at T8-L1 in approximately 75% of patients. Ligation of the segmental arteries at these levels on the left risks anterior spinal artery syndrome and paraplegia. Pre-operative angiography or contrast-enhanced MRI to identify its location is strongly recommended.

Retroperitoneal Approach (Lumbar Spine, L1-L5)

Position: Right lateral decubitus (left side up) for the standard left retroperitoneal approach — the aorta is easier to mobilise than the IVC, and the liver does not obstruct.

Structures at risk:

• Peritoneum — carefully retracted medially; breach requires repair
• Ureter — identified by its peristalsis; protect with a vessel loop
• Psoas muscle — retracted laterally; the genitofemoral nerve lies on its surface
• Sympathetic chain — on the anterolateral vertebral body; injury produces a warm right leg (sympathectomy effect)
• Lumbar segmental vessels (artery and vein) — cross the mid-vertebral body; must be ligated to access the spine
• Aorta (left side) and IVC (right side) — retract carefully; the aorta can be mobilised off the spine
• Iliac vessels — cross the L4-L5 disc; a common site for vascular injury

Thoracolumbar Approach (T10-L2)

Combines a lower thoracotomy with a retroperitoneal exposure — the diaphragm is divided circumferentially 2-3 cm from its costal insertion, leaving a cuff for repair.

Key structures: The diaphragm is innervated by the phrenic nerve (C3-C5) — radial incisions risk denervation. A circumferential incision near the costal insertion preserves innervation.

Applied Surgical Anatomy — Summary Table

Pre-Operative Planning

Imaging

• Plain radiographs: AP and lateral full-length standing views — assess kyphosis (Cobb angle), vertebral body loss, disc space narrowing, paravertebral shadow
• MRI with gadolinium: Gold standard — defines the extent of vertebral body involvement, thecal sac compression, paravertebral/psoas abscesses, skip lesions, and cord oedema (myelomalacia)
• CT scan: For surgical planning — assesses bone destruction pattern, endplate quality, pedicle morphology for screw placement, and vascular anatomy with contrast
• CT-guided biopsy: If there is diagnostic uncertainty (atypical imaging, no positive culture, concern for malignancy) — obtain tissue for histology, culture, sensitivity and molecular testing (GeneXpert)

Medical Optimisation

• Start ATT: At least 2-4 weeks of four-drug regimen before elective surgery is preferred to reduce the bacterial load and the risk of implant infection. In urgent cases (progressive neurological deficit), surgery can proceed after 1-2 weeks of ATT — do not delay decompression.
• Nutritional assessment: Correct malnutrition — serum albumin greater than 30 g/L, adequate caloric and protein intake
• Assessment of pulmonary function: For thoracotomy — spirometry, arterial blood gases. Optimise with chest physiotherapy pre-operatively.
• Blood conservation: Cross-match 2-4 units. Cell saver is useful. The combined anterior-posterior procedure can have significant blood loss.
• Consent: Specifically counsel regarding risk of neurological deterioration (1-3%), graft/cage subsidence, implant failure, recurrence, approach-specific complications (intercostal neuralgia, dural leak, vascular injury, pleural effusion, chylothorax), and the need for a 12-month course of ATT.

Positioning

Anterior Approach (Transthoracic or Retroperitoneal)

• Position: Lateral decubitus — right side down for a RIGHT thoracic approach (left side up) for upper and mid-thoracic; left side down for a LEFT retroperitoneal approach to the lumbar spine
• Table: Flex the table slightly to open the intercostal space or the space between the iliac crest and rib cage
• Padding: Axillary roll (protect the brachial plexus), pillows between knees, all bony prominences padded
• Arm: The down arm is placed on an arm board at less than 90 degrees abduction; the up arm is supported on a padded Mayo stand or arm holder
• Verification: Check that surgical access to the iliac crest (for graft harvest) is possible without repositioning — the patient may need to be positioned more posteriorly on the table

Posterior Approach (Instrumentation)

• Position: Prone on a Jackson table (or four-poster frame) — abdomen free to reduce venous pressure and blood loss
• Head: Neutral position in a foam headrest or Mayfield pins if upper thoracic/cervicothoracic
• Arms: Positioned at less than 90 degrees abduction on arm boards, elbows slightly flexed
• Legs: Slightly flexed at hips and knees, all bony prominences padded
• Fluoroscopy: Position C-arm for AP and lateral imaging before draping

Combined Procedure

• Staged (same day): The posterior instrumentation is performed FIRST (prone) or the anterior debridement FIRST (lateral), then the patient is repositioned for the second stage. Some surgeons prefer posterior first (allows temporary stabilisation before anterior debridement). Others prefer anterior first (achieves debridement and decompression, then correction with posterior instrumentation).
• Staged (separate days): Anterior debridement and grafting is performed first, followed by posterior instrumentation 7-14 days later. This allows the patient to recover from the higher-morbidity anterior approach before the posterior procedure.

Step-by-Step Operative Technique — Anterior Debridement and Anterior Column Reconstruction

Step 1: Surgical Approach

Thoracic level (T2-T10):

1. Make the skin incision along the intercostal space. For upper thoracic (T2-T5), an incision over the 3rd or 4th rib. For mid-thoracic (T5-T9), over the 5th or 6th rib. For T9-T10, over the 7th or 8th rib.
2. Divide the latissimus dorsi, serratus anterior and intercostal muscles in line with the incision.
3. Enter the pleural cavity through the chosen intercostal space. Avoid injury to the intercostal neurovascular bundle — stay on the superior border of the rib.
4. Insert a self-retaining rib retractor (e.g. Finochietto) and open gently to avoid rib fracture.
5. Deflate the ipsilateral lung (double-lumen endotracheal tube required) and retract it medially with wet laparotomy pads.
6. Identify the diseased vertebral level by palpating the prominent kyphosis and checking with a lateral radiograph or fluoroscopy.
7. Incise the parietal pleura over the vertebral bodies. Identify and ligate the segmental vessels (artery and vein) at the mid-vertebral body level — use silk ties or haemostatic clips. Preserve the segmental vessels at the level identified for the artery of Adamkiewicz.
8. Elevate and retract the ligated vessel stumps with the pleura to expose the anterolateral vertebral bodies.

Lumbar level (L1-L5):

1. Position the patient lateral with the left side up (left retroperitoneal approach is standard).
2. Make an oblique incision from the 12th rib tip to the lateral border of the rectus abdominis, centred over the affected level.
3. Divide the external oblique, internal oblique and transversus abdominis muscles in the line of the incision.
4. Identify the retroperitoneal space — the peritoneum is swept medially with a wet swab. Identify the psoas muscle and ureter (peristaltic, confirmed by gently squeezing).
5. Retract the ureter and peritoneum medially. Identify the great vessels (aorta on the left, IVC on the right).
6. Ligate the lumbar segmental vessels crossing the mid-vertebral body at the affected level. Mobilise the aorta/IVC medially to expose the vertebral body.
7. Confirm the level with fluoroscopy.

Step 2: Radical Debridement

1. Identify the affected vertebral bodies — the bone is soft, necrotic and discoloured. There is loss of normal trabecular architecture.
2. Remove the affected intervertebral discs above and below the diseased segment — excise the annulus and nucleus completely.
3. Begin debridement of the vertebral body using rongeurs, curettes and pituitary forceps. Remove all caseous material, pus, sequestra, granulation tissue and necrotic bone.
4. Continue debridement until healthy cancellous bone that bleeds freely is reached and firm, structural endplate bone is present at the cranial and caudal prepared surfaces.
5. Use a high-speed burr if necessary to define healthy bone margins.
6. Open the posterior longitudinal ligament with a nerve hook or micro-rongeur to inspect the spinal canal. Remove any retropulsed bone fragments, disc material or epidural granulation tissue compressing the thecal sac.
7. Verification: The debridement cavity should be a rectangular trough of healthy bleeding bone from the healthy vertebral body above to the healthy vertebral body below, and from the posterior longitudinal ligament anteriorly to the anterior longitudinal ligament (or paravertebral plane) posteriorly. Any remaining discoloured or soft bone at the margins indicates incomplete debridement.

Step 3: Anterior Column Reconstruction

Selection of reconstruction method — graft or cage:

Technique for tricortical iliac crest strut grafting:

1. Harvest a full-thickness tricortical graft from the ipsilateral anterior iliac crest through a separate incision. The graft should be 5-10 mm longer than the measured defect to achieve a press-fit.
2. Create a notch in the superior endplate of the vertebra above and the inferior endplate of the vertebra below using an osteotome or high-speed burr.
3. Insert the graft under distraction. The graft should be countersunk 3-5 mm into the notches.
4. Release distraction — the graft is now under compression. The graft should be stable to gentle manual testing.
5. Fill any remaining gaps with morsellised autograft (local bone harvested from the debrided vertebral bodies, separated from necrotic material).

Technique for titanium mesh cage:

1. Measure the defect height after gentle distraction.
2. Select a cage diameter that matches or slightly exceeds the width of the prepared vertebral body endplate (ideally 80-90% of the endplate width).
3. Fill the cage with morsellised autograft (harvested during debridement — healthy bone chips separated from necrotic tissue).
4. Impact the cage into the defect under distraction. The cage must sit on the ring apophysis (peripheral endplate — the strongest part) rather than the central endplate.
5. Release distraction and confirm cage stability.

Step 4: Wound Closure (Anterior Stage)

1. Irrigate the wound copiously with normal saline.
2. Achieve meticulous haemostasis — use bipolar cautery for epidural bleeding, bone wax for cancellous bone surfaces, and Surgicel or similar for oozing surfaces.
3. Place a chest tube (thoracotomy — 28-32 Fr) in the pleural space, brought out through a separate stab incision below the thoracotomy wound.
4. Close the thoracotomy incision in layers: pleural cavity closed with running absorbable suture (watertight), intercostal muscles, serratus anterior, latissimus dorsi, subcutaneous tissue and skin.
5. For the retroperitoneal approach, place a retroperitoneal drain and close in anatomical layers.

Step-by-Step Operative Technique — Posterior Instrumented Fusion

Step 1: Positioning and Exposure

1. Reposition the patient prone (if combined procedure) and prepare the posterior spine.
2. Make a midline incision centred over the affected level, extending one to two levels above and below the instrumented segment.
3. Subperiosteal dissection of the paraspinal muscles from the spinous processes and laminae to expose the transverse processes bilaterally.

Step 2: Pedicle Screw Placement

1. Identify the entry points using standard landmarks: at the junction of the transverse process and the facet joint (thoracic) or at the intersection of the mid-transverse process line with the lateral border of the pars (lumbar).
2. Use a pedicle finder to create the screw channel. Confirm with fluoroscopy (AP and lateral) or navigation.
3. Insert pedicle screws one to two levels above and below the diseased segment. The diseased segment itself usually cannot accept screws due to bony destruction.
4. Confirm screw position with fluoroscopy.

Step 3: Deformity Correction

1. Place pre-contoured rods on both sides.
2. Perform kyphosis correction with a combination of techniques: rod rotation (rotating a pre-contoured rod from the sagittal profile into the coronal plane), compression/distraction across the screws (compression posteriorly to close the posterior column and reduce the kyphosis), and cantilever reduction.
3. The surgeon should aim for approximately 20-30 degrees of kyphosis correction — the anterior graft/cage will maintain anterior column height while the posterior instrumentation holds the correction.
4. Apply the final tightening of set screws.

Step 4: Fusion and Closure

1. Decorticate the laminae and transverse processes at all instrumented levels. Place morsellised autograft (from the posterior exposure or local bone saved from the anterior debridement) over the decorticated surfaces.
2. Place a drain over the closure and close in layers: fascia (absorbable running suture), subcutaneous tissue and skin.

Combined Sequence — The Surgeon's Decision

Post-Operative Protocol

Immediate Post-Operative Phase (Day 0-3)

• ICU or high-dependency unit: First 24-48 hours for monitoring of respiratory status (thoracotomy patients), haemodynamics and neurological observation
• Chest tube management (thoracotomy): Maintain underwater seal at 20 cm H2O suction. Remove when drainage is less than 100-150 mL per 24 hours and there is no air leak — typically day 2-4. Routine chest radiograph after removal
• Neurological observation: Hourly motor/sensory checks for the first 24 hours; if stable, then 4-hourly
• Antibiotics: Perioperative IV antibiotics (cefazolin) for 24 hours; continue beyond 24 hours only if active infection suspected
• ATT: Restart the full four-drug regimen on day 1 post-operatively (may be given via nasogastric tube if not yet tolerating oral intake)
• Thromboprophylaxis: Mechanical (compression stockings, sequential compression devices) immediately; chemical prophylaxis (LMWH) starting 24-48 hours post-operatively
• Mobilisation: Out of bed to chair on day 1-2 with the brace on; commence walking on day 2-3 with physiotherapy

Bracing Protocol

• Type: Custom-made thoracolumbosacral orthosis (TLSO) for thoracic and lumbar disease; cervical-thoracic brace (e.g. SOMI or Halo-vest) for cervical disease
• Duration: 3-6 months post-operatively
• Wear regimen: Full-time wear (removed only for showering and sleeping once skin tolerance develops) for the first 3 months, then wean over 4-6 weeks
• Skin checks: Daily — inspect for pressure areas over bony prominences (iliac crest, sternum, occiput)

ATT Protocol (Post-Surgery)

• Standard duration: 12 months total (counting from the start of treatment)
• Regimen: Rifampicin (450-600 mg daily) + Isoniazid (300 mg daily) + Pyrazinamide (25 mg/kg daily) + Ethambutol (15 mg/kg daily) for the first 2 months, then Rifampicin + Isoniazid for the remaining 10 months
• Monitoring: Monthly LFTs (rifampicin and isoniazid are hepatotoxic), visual acuity (ethambutol optic neuritis), and clinical response
• Compliance strategy: Directly observed therapy (DOT) if there are concerns about compliance. Pill count at each follow-up.
• If MDR TB: Second-line agents (fluoroquinolones, aminoglycosides, ethionamide, cycloserine) under ID guidance — requires extended ATT (18-24 months)

Follow-Up Schedule

When to Obtain MRI: Neurological deterioration (new or progressive deficit), recurrent pain at the surgical site, suspected recurrence or reactivation, or suspected implant-related complications.

Return to Function

• Walking: Day 2-3 with brace and physiotherapy
• Driving: 6-8 weeks (must be free from opiate analgesia and able to perform an emergency stop)
• Sedentary work: 6-12 weeks depending on pain and bracing requirements
• Manual work / heavy lifting: 6-9 months; must have solid radiographic fusion before unrestricted activity
• Sports: Non-contact sports (swimming, cycling) at 6 months; contact sports at 12 months with confirmed solid fusion

Special Case: Paediatric Spinal Tuberculosis

Key Differences from Adult Disease

• The growing spine compensates poorly for anterior column loss — progressive kyphosis occurs as the posterior elements continue to grow while the anterior column is fused
• Spinal canal compromise is better tolerated in children — more recovery potential but also a greater capacity for late neurological deterioration as the deformed canal narrows with growth
• The graft must accommodate growth — either use an autograft that can remodel (rib graft) or plan for staged lengthening/revision after skeletal maturity

Surgical Principles in Children

• More aggressive surgical approach is justified — combined anterior-posterior reconstruction for any child with more than 20 degrees of kyphosis or 'spine at risk' signs
• Autograft (rib or iliac crest) is preferred over cages — autograft can remodel and incorporate more naturally with the growing spine
• Posterior instrumentation: use growth-friendly constructs (growing rods, or a limited fusion that can be extended as the child grows) rather than a single long fusion that restricts thoracic growth
• ATT remains the same (weight-based dosing) — 12-month regimen

Kyphosis Prevention in Children

Rajasekaran's formula predicts the final kyphosis based on the initial vertebral body loss:

• Loss of less than one and a half vertebral bodies: final kyphosis less than 30 degrees — may be managed with chemotherapy alone
• Loss of one and a half to two bodies: final kyphosis 30-60 degrees — combined anterior-posterior surgery recommended
• Loss of greater than two bodies: final kyphosis greater than 60 degrees — combined surgery is mandatory with extended posterior instrumentation

Special Case: Multi-Level Disease (More than 2 Vertebral Bodies)

Surgical Challenges

• Longer anterior reconstruction spans more levels — graft/cage is at greater risk of subsidence and failure
• More levels of posterior instrumentation needed — greater blood loss, longer operative time, higher infection risk
• Greater kyphosis correction needed — more complex deformity correction
• Post-operative bracing is required for longer (6 months minimum)

Surgical Strategy

• Combined anterior-posterior approach is mandatory
• Anterior reconstruction: a long strut graft (fibular autograft or long cage) spanning the entire diseased segment. The footplates of the construct must sit on healthy vertebral bodies at both ends
• Posterior instrumentation: extend 2-3 levels above and below the diseased segment
• Consider staged surgery (anterior then posterior 7-14 days later) to reduce the physiological burden

Special Case: Drug-Resistant Spinal Tuberculosis

Pre-Operative Considerations

• MDR-TB (resistant to rifampicin and isoniazid) requires second-line ATT for 18-24 months
• Surgery in MDR-TB carries a high risk of implant infection and wound complications — indication for surgery must be strong
• Obtain drug sensitivity testing from pre-operative biopsy (GeneXpert, line probe assay or culture and sensitivity)
• ID consultation mandatory before proceeding with surgery

Surgical Considerations

• More radical debridement is necessary — all necrotic and infected tissue must be removed at the time of surgery
• Implant infection risk is elevated (10-20%) — consider a titanium implant that may be better tolerated than stainless steel
• Post-operative wound surveillance is essential — any wound drainage requires aggressive management (washout and culture)
• Prolonged post-operative ATT (18-24 months) under ID supervision

When to Consider Non-Operative Management (Decision Algorithm)

Patient with active spinal TB

Step 1: Start ATT (4-drug regimen)

Step 2: Assess at 4-6 weeks

• Neurological deficit? YES → Surgery (after 2-4 weeks of ATT)
• Kyphosis greater than 30 degrees? YES → Surgery (combined anterior-posterior)
• 'Spine at risk' signs in child? YES → Surgery
• Instability on dynamic views? YES → Surgery
• Large abscess with significant compression? YES → Consider drainage ± surgery

Step 3: If NONE of the above → Continue ATT alone

• Monitor with radiographs at 3, 6, 12 months
• If neurological deterioration develops → Convert to surgical management urgently
• If kyphosis progresses beyond 30 degrees → Convert to surgical management
• If pain persists beyond 3 months of ATT without other cause → Consider surgery for mechanical instability