Spondylolisthesis

Modern Study Review (AI-Generated)

High-Yield Summary

Spondylolisthesis is the anterior displacement of a vertebral body relative to the one below, commonly affecting the lumbar spine. It is classified by etiology, with dysplastic, isthmic, degenerative, traumatic, and post-surgical types guiding diagnosis and management. Clinical focus is on pain relief and preservation of neurological function, with treatment tailored to symptom severity, slip grade, and risk of progression. Modern management emphasizes evidence-based indications for conservative care versus surgical stabilization, with advances in instrumentation improving outcomes but requiring careful patient selection.

Key Diagnostic Findings

Anatomy

• Pars interarticularis: Common site of defect in isthmic spondylolisthesis.
• Facet orientation: Dysplastic type involves abnormal facet joint orientation (axial or sagittal), influencing slip risk and neural compression.
• Common levels: L5-S1 for isthmic in adolescents; L4-L5 for degenerative in adults.

Clinical Presentation

• Adolescents: Often present with low back pain, sometimes asymptomatic slips found incidentally.
• Adults: Degenerative spondylolisthesis presents with neurogenic claudication or radiculopathy.
• Neurological deficits (motor weakness) indicate nerve root compression requiring surgical decompression.

Imaging

• X-rays: Standing lateral views to assess slip percentage and slip angle (lumbosacral kyphosis).
• MRI: Evaluates neural element compression and disc degeneration.
• CT: Useful for detailed bony anatomy, especially pars defects.

Classification Systems

Current Gold Standard Treatment

Non-operative Indications and Treatment

• Indications: Asymptomatic or mild symptoms, low-grade slips (Grade I-II), no neurological deficits.
• Management: Activity modification (avoid hyperextension/contact sports), NSAIDs, physical therapy focusing on core strengthening and flexibility.
• Monitoring: Serial imaging to assess progression, especially during adolescent growth spurts; frequency decreases after skeletal maturity.

Operative Indications and Treatment

• Indications:
• Persistent pain despite conservative care.
• Neurological deficits (motor weakness).
• High-grade slips (Grade III-IV) or progressive slip >50%.
• Radiographic risk factors for progression (high slip angle, trapezoidal L5, rounded sacrum).

• Surgical Options:
• Posterolateral fusion (PLF): In situ fusion with bone graft, traditionally from L5-S1 for low-grade slips; extended to L4-S1 for high-grade slips to address biomechanical stress.
• Instrumented fusion: Pedicle screw fixation with or without reduction; indicated when decompression destabilizes the spine or in high-grade slips with neurological symptoms.
• Decompression: Reserved for patients with motor deficits; requires instrumentation due to destabilization.

• Positioning: Prone with hips and legs extended to avoid worsening lumbosacral kyphosis and prevent cauda equina syndrome intraoperatively.

Modern Complications & Outcomes

Complications

Outcomes

• Non-operative: Most low-grade slips remain stable with conservative care; pain control and function improve in majority.
• Surgical: Fusion provides durable pain relief and halts progression; instrumented fusion shows higher fusion rates and earlier mobilization.
• Neurological recovery: Dependent on severity and duration of deficits preoperatively. Early decompression improves outcomes.
• Long-term: Patients require monitoring for adjacent segment degeneration and hardware complications.

Classic Clinical Notes

Spondylolisthesis

Approach to Spondylolisthesis

Wiltse Classification (“Did Tim Pass”)

• I – Dysplastic
• IA – axially oriented facets
• IB – sagittally oriented facets
• Dysplastic facets permit forward translation – higher chance for neural compression as the intact posterior elements move forwards

• II – Isthmic
• IIA – lytic defect in pars
• IIB – elongated (partially healed lytic lesion)

• III – Degenerative

• IV – Traumatic

• V – Post-Surgical

• Children get isthmic spondylolysis and spondylolisthesis at L5/1; adults get degenerative spondy at L4/5.
• An acquired disorder; possibly a stress fracture of the pars after repetitive microtrauma.
• Increase in slippage is seen during adolescent growth spurt; progression is unlikely after adolescence; therefore, like in adolescent scoliosis, get an idea of how skeletally mature they are when deciding about risk of progression.
• Initial slippage of 50% is predictive of further slippage.
• Slip angle measures lumbosacral kyphosis and is associated with a higher risk of progression.
• Look for a rounded off sacrum or trapezoidal L5 body – higher chance of progression.

Approach

• Grade I and II slips that are asymptomatic (found spuriously)
• Observation semiannually until age 15, then annually until the end of growth.
• May give them advice about avoiding hyperextension activities and contact sports.
• A 20% slip that progresses to 35% is not necessarily an indication for fusion – assess the above factors and watch closely. Look at skeletal maturity, high slip angle, rounded sacrum or trapezoidal shape of L5 as useful markers of progression.
• A 20% slip that progresses to 50% is probably an indication that you better get on and fuse it.

• Grade I and II slips with pain
• Activity restriction, NSAIDs, local measures, stretching exercises.
• If continues to have pain – thoracolumbar orthosis.
• If pain persists with orthosis, can do a L5-S1 posterolateral in-situ fusion with bone graft followed by single or double leg hip spica cast.

• Grade III or IV slips with or without symptoms
• Gets a L4-S1 posterolateral in situ fusion with bone graft as a preventative measure for further progression if they are asymptomatic. Must extend fusion up to L4 because of the biomechanical disadvantage of the fusion mass.
• Instrumented fusions are becoming popular but do not have the long-term track record of the standard posterolateral uninstrumented in-situ fusion. Instrumented reduction is hazardous to the nerve roots.
• If they have documented MOTOR weakness, you should probably decompress them, which also means that you are going to go midline and destabilize them – they need to be instrumented.
• When you position them prone in the OR, position them with their hips and legs EXTENDED – if you allow them to flex like they normally do, their lumbosacral kyphosis worsens, and they are apt to get a cauda equina syndrome. Cauda equina can occur with reductions and with in-situ fusions as well – requires sacroplasty.

Last Updated on January 25, 2026 by orthonet