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Spondylolisthesis — MS Orthopaedics (10 Marks)

Definition

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Classification — Wiltse, Newman & McNab (6 Types)

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Grading — Meyerding Classification

• Slip angle (normally <0°, i.e., lordotic at L5–S1 disc) — quantifies kyphosis at the slip level
• Sacral inclination (normally >30°)
• Pelvic incidence (PI) (normally ~50°) — predicts intervention and prognosis

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Epidemiology & Natural History

• Prevalence ~4–6% in the general population
• Isthmic type: most common in White males, gymnasts, football linemen (repetitive hyperextension stress)
• Degenerative type: most common in women >40 years at L4–L5
• Most common symptomatic level: L5–S1 (isthmic); L4–L5 (degenerative)
• Unilateral pars defects rarely progress to slip
• Slip progression slows in adulthood; degeneration of the disc → foraminal stenosis → L5 root compression

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Clinical Features

Symptoms

• Low back pain — most common; worse on extension; relieved by flexion
• Radicular pain — L5 root (isthmic, foraminal compression); bilateral L5 (high-grade)
• Neurogenic claudication — in degenerative type with canal stenosis
• Cauda equina syndrome — bladder/bowel dysfunction; rare but emergency

Signs

• Palpable step-off deformity at lumbosacral junction
• Flattening of lumbar lordosis
• "Pelvic waddle" gait in severe cases
• Hamstring tightness (reflex protective spasm — a hallmark in children/adolescents)
• "Heart-shaped" buttocks — in high-grade slips due to posterior displacement of sacrum
• Restriction of lumbar flexion/extension
• Neurological deficit: weakness of EHL (L5), reduced ankle reflex (S1)

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Investigations

Radiography (Plain X-ray) — Primary Investigation

• Lateral view: best to visualize slip, Meyerding grading, slip angle
• AP view: inverted Napoleon's hat sign (Grade IV–V)
• Oblique view (45°): shows the "Scotty dog" sign; a collar/break around the neck = pars defect (spondylolysis)
• 80% of pars lesions visible on lateral; 15% additional on oblique

Other Imaging

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Treatment

Conservative (Non-operative)

• Activity modification (avoid hyperextension sports — gymnastics, football)
• Flexion exercises (Williams' exercises); core strengthening
• NSAIDs for pain
• Bracing (thoracolumbosacral orthosis) — especially in adolescents with acute pars stress reaction
• Epidural steroid injections for radicular symptoms
• Adolescents with Grade I may return to contact sports once asymptomatic
• Grade II asymptomatic → restricted from gymnastics and football; regular radiological follow-up

Indications for Surgery

1. Progressive slip (especially in skeletally immature patients)
2. Neurological deficit (motor weakness, cauda equina syndrome)
3. High-grade slip (Grades III–IV)
4. Intractable pain failing ≥6 months conservative management
5. Cosmetically unacceptable deformity

Surgical Options

Low-Grade Slips (Grades I–II)

• Posterolateral fusion in situ — procedure of choice; L4–S1 fusion with pedicle screw instrumentation
• If neural compression present → decompression + fusion (posterior lumbar interbody fusion/PLIF or TLIF)
• Gill's procedure (excision of loose Gill fragment/fibrocartilaginous mass at pars) alone is not recommended as it increases instability; must be combined with fusion

High-Grade Slips (Grades III–IV)

• Reduction + instrumented fusion vs in-situ fusion — controversial
• Reduction risks: L5 root neurapraxia (traction injury) — must be done slowly with wake-up tests or neurophysiological monitoring
• Circumferential fusion (anterior + posterior) often required for high-grade slips
• Spondyloptosis (Grade V): partial reduction followed by fusion

Degenerative Spondylolisthesis

• Decompression (laminectomy/laminotomy) alone is inadequate if there is instability
• Decompression + posterolateral fusion ± pedicle screws (instrumented fusion gives better outcomes)

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Complications

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Key Points for Exam (Scoring Points)

1. Definition: Forward slip of one vertebra on another
2. Wiltse classification — 6 types; isthmic most common
3. Meyerding grading — 5 grades; Grades I–II = low-grade, III–IV = high-grade, V = spondyloptosis
4. Scotty dog sign on oblique X-ray — pars defect (spondylolysis)
5. Clinical hallmarks: palpable step-off, hamstring tightness, pelvic waddle, heart-shaped buttocks
6. Radiological measurements: slip %, slip angle, sacral inclination, pelvic incidence
7. Conservative treatment for low-grade, asymptomatic or mildly symptomatic
8. Fusion in situ for low-grade surgical cases; decompression added if neural compromise
9. High-grade: in-situ vs. reduction-and-fusion debate; neurological risk of L5 neurapraxia
10. Degenerative type: decompression + fusion; decompression alone → higher recurrence

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Cervical Spondylolisthesis

Definition

1. Traumatic cervical spondylolisthesis — most notably Hangman's fracture (traumatic spondylolisthesis of C2)
2. Degenerative cervical spondylolisthesis — slip secondary to disc and facet degeneration, most common in the subaxial spine (C3–C5)

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Types / Classification

A. Traumatic Cervical Spondylolisthesis

1. Hangman's Fracture (Traumatic Spondylolisthesis of the Axis — C2)

2. Subaxial Traumatic Spondylolisthesis (C3–C7)

• Unilateral facet dislocation: ~25% anterior slip, rotational deformity
• Bilateral facet dislocation (perched facets): ≥50% anterior slip; high risk of cord injury
• Teardrop fracture-dislocation: hyperflexion; severe cord injury common

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B. Degenerative Cervical Spondylolisthesis

Dean et al. Classification (2 types):

• Type I (Adjacent type) — more common; slip occurs adjacent to a relatively stiff, spondylotic cervical segment (the mobile segment next to the stiff one bears excess load)
• Type II (Spondylotic type) — slip occurs within the spondylotic segment itself

Woiciechowsky et al. Classification (3 types):

• Type 1: Spondylolisthesis with facet joint degeneration only
• Type 2: Spondylolisthesis with degeneration of facet joints AND vertebral bodies/discs
• Type 3: Spondylolisthesis with severe cervical spine deformity

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Epidemiology

• Degenerative cervical spondylolisthesis: most common at C3/4 (46%) and C4/5 (49%)
• Prevalence in the general population: lower than lumbar; often underdiagnosed
• More common in elderly; no clear gender predisposition in degenerative type
• 46% of patients demonstrate segmental instability on flexion-extension radiographs

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Pathophysiology

Degenerative Type

1. Disc degeneration → disc space narrowing → increased load transfer to facet joints
2. Facet arthropathy → capsular laxity → segmental instability
3. Forward slip of the superior vertebra → dynamic or fixed spondylolisthesis
4. Secondary changes: osteophyte formation, ligamentum flavum hypertrophy, uncovertebral joint hypertrophy → canal and foraminal stenosis
5. Spinal cord compression → myelopathy; foraminal compression → radiculopathy

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Clinical Features

1. Traumatic Cervical Spondylolisthesis

• History of high-energy trauma (MVA, fall from height, diving)
• Neck pain, restricted movement
• Variable neurology: may be neurologically intact (Hangman's) or have complete cord injury (bilateral facet dislocation)
• Signs of cord injury: spastic quadriparesis, sensory level, bladder/bowel dysfunction
• Diaphragm sparing: C3/C4 injuries may spare breathing if partial

2. Degenerative Cervical Spondylolisthesis

• Upper limbs: Weakness and wasting of hand intrinsics (C8/T1); clumsy hands; loss of fine motor dexterity
• Lower limbs: Spastic paraparesis, scissor gait, wide-based gait; Babinski sign positive
• Lhermitte's sign: Electric shock sensation down spine on neck flexion
• Hoffman's sign: Positive (flicking middle finger → thumb flexion)
• Hyperreflexia below the level; hyporeflexia/LMN signs at the level
• Inverted radial reflex: Pathognomonic of C5/6 cord lesion
• Numbness and paresthesias in hands (often earliest symptom)

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Investigations

Radiography

• Lateral X-ray: Best for alignment; anterior slip, disc height loss, osteophytes
• Flexion-extension views: Essential for demonstrating dynamic instability; >3.5 mm translation or >11° angulation = instability (White & Panjabi criteria)
• CT scan (with sagittal reconstruction): Bone detail, fracture characterization, facet morphology
• CTMM (CT myelogram): When MRI contraindicated

• Anterior vertebral slip (Grade I most common)
• Disc space narrowing
• Osteophyte formation
• Facet hypertrophy
• Loss of cervical lordosis or focal kyphosis

MRI — Investigation of Choice for Neural Compression

• Degree of canal compromise
• Cord signal changes (T2 hyperintensity = myelomalacia — poor prognostic sign)
• Disc degeneration, ligamentum flavum hypertrophy
• Neural foraminal stenosis

EMG/NCS

• Differentiates radiculopathy from peripheral neuropathy
• Identifies level of root compression

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Treatment

Conservative Management

• Cervical collar/immobilisation (Philadelphia collar for Hangman's Type I–II)
• Halo vest: for Hangman's Type II, displaced injuries requiring reduction and immobilisation
• NSAIDs, analgesics
• Cervical traction (Gardner-Wells tongs) for closed reduction of facet dislocations — contraindicated in Type IIa Hangman's (risk of distraction injury)
• Physiotherapy: cervical stabilisation exercises, traction, heat
• Epidural steroid injections for radiculopathy

Surgical Management

1. Myelopathy (progressive or severe)
2. Radiologically proven instability (>3.5 mm slip or >11° angulation)
3. Neurological deficit (radiculopathy with objective motor weakness)
4. Failed conservative management (>6–12 weeks)
5. Hangman's Types II, IIa, III — unstable injuries
6. Spinal cord compression with signal change on MRI

For Degenerative Spondylolisthesis

For Traumatic Spondylolisthesis

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Key Differences from Lumbar Spondylolisthesis

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Summary — Points for Exam

1. Traumatic: Hangman's fracture (C2) — hyperextension; Levine-Edwards 4 types; often neurologically intact due to canal widening
2. Degenerative: C3/4, C4/5; disc + facet arthropathy; 64% present with myelopathy
3. Dean's classification: Type I (adjacent to stiff segment) vs. Type II (within spondylotic segment)
4. Stability criteria: >3.5 mm translation OR >11° angulation = instability (White & Panjabi)
5. MRI: investigation of choice; T2 cord signal change = myelomalacia = poor prognosis
6. Flexion-extension X-rays: essential to demonstrate dynamic instability
7. Lhermitte's + Hoffman's + inverted radial reflex: hallmarks of cervical myelopathy
8. ACDF: standard procedure for 1–2 level disease
9. Type IIa Hangman's: DO NOT apply traction — extension + halo
10. Posterior stabilisation for Type III Hangman's and bilateral facet dislocations

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