Spinal surgery fundamentals

Spinal surgery fundamentals

Spinal surgery fundamentals

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🦴 Anatomy - The Bony Framework

  • Vertebral Column: 33 vertebrae total.
    • Cervical: 7 (C1-C7)
    • Thoracic: 12 (T1-T12)
    • Lumbar: 5 (L1-L5)
    • Sacral: 5 (fused into sacrum)
    • Coccygeal: 4 (fused into coccyx)
  • Typical Vertebra Components:
    • Anterior: Vertebral Body (weight-bearing).
    • Posterior Arch: Pedicles, Laminae, Spinous Process, Transverse Processes, and Articular Facets (form zygapophyseal joints).
  • Atypical Vertebrae:
    • C1 (Atlas): Ring-like, no body.
    • C2 (Axis): Has dens (odontoid process) for pivot rotation.

Typical vertebra anatomy: superior and lateral views

Jefferson Fracture: A burst fracture of the C1 ring from axial loading (e.g., diving injury). On open-mouth X-ray, look for lateral displacement of C1's lateral masses relative to C2.

🧠 Anatomy - Neurological & Vascular Supply

  • Spinal Cord: Ends as the conus medullaris at the L1-L2 vertebral level in adults. Nerve roots below this form the cauda equina.
  • Key Nerve Roots (Myotomes):
    • C5: Deltoid (shoulder abduction)
    • C7: Triceps (elbow extension)
    • L4: Quadriceps (knee extension)
    • L5: Tibialis anterior (foot dorsiflexion)
    • S1: Gastrocnemius (foot plantarflexion)
  • Arterial Supply:
    • Anterior Spinal Artery (ASA): Single artery supplying the anterior 2/3 of the cord (motor pathways).
    • Posterior Spinal Arteries (PSAs): Paired arteries supplying the posterior 1/3 (sensory pathways).

⭐ The Artery of Adamkiewicz is the largest segmental artery, crucial for lower cord perfusion. Ischemia leads to Anterior Cord Syndrome-bilateral paralysis and loss of pain/temp, with preserved dorsal column function.

Spinal cord arterial supply territories

🔪 Surgical Approaches & Corridors

  • Goal: Safely access spinal pathology while minimizing iatrogenic injury. The corridor choice is dictated by pathology location (e.g., anterior disc vs. posterior lamina), spinal level, and surgeon preference.
ApproachCorridor & Key StructuresCommon Uses⚠️ Key Risks
AnteriorRetroperitoneal (lumbar); between carotid/trachea (cervical)ACDF, ALIF, CorpectomyGreat vessels, recurrent laryngeal nerve (RLN), esophagus
PosteriorMidline, splitting paraspinal musclesLaminectomy, Discectomy, Pedicle screw fixationDural tear, nerve root injury, post-op muscle pain
LateralTranspsoas (XLIF), retroperitonealLateral interbody fusion (L1-L5)Lumbar plexus injury, psoas hematoma/weakness

🩺 Clinical - Indications & Pathologies

  • Degenerative Disease (Most Common):
    • Herniated Nucleus Pulposus (HNP): For radiculopathy or myelopathy refractory to conservative care.
    • Spinal Stenosis: Central or foraminal, causing neurogenic claudication.
    • Spondylolisthesis: Instability with back pain or radiculopathy.
  • Trauma:
    • Unstable fractures (e.g., Burst, Chance) or ligamentous injury.
    • Spinal Cord Injury (SCI) with persistent cord compression.
  • Oncology:
    • Metastatic disease (📌 BLT w/ Kosher Pickle) or primary tumors causing instability or neurologic deficit.
  • Infection:
    • Spinal Epidural Abscess, Vertebral Osteomyelitis/Discitis with instability or neurologic compromise.

Cauda Equina Syndrome (saddle anesthesia, bowel/bladder dysfunction, bilateral leg weakness) is a neurosurgical emergency requiring immediate decompression.

MRI Lumbar Spine: L4-L5 Disc Herniation & Nerve Compression

⚠️ Complications - Post-Op Pitfalls

  • Infection: Superficial or deep (discitis, epidural abscess). ↑ risk with diabetes, obesity.
  • Dural Tear / CSF Leak: Presents as postural headache. Test fluid for β-2 transferrin.
  • Hardware Failure: Malposition, loosening, or fracture of screws/rods.
  • Neurologic Deficit: New or worsening weakness/numbness from nerve root injury or hematoma.
  • Epidural Hematoma: Surgical emergency causing rapid neuro decline.

⭐ Post-op epidural hematoma causing cauda equina syndrome (saddle anesthesia, bowel/bladder dysfunction) requires immediate surgical decompression.

⚡ Biggest Takeaways

  • Cauda Equina Syndrome is a surgical emergency: presents with saddle anesthesia, bowel/bladder dysfunction, and requires urgent decompression.
  • For suspected spinal cord compression, give IV dexamethasone immediately, followed by an emergent MRI.
  • Radiculopathy (nerve root) causes LMN signs in a dermatome; Myelopathy (cord) causes UMN signs below the lesion.
  • Spinal stenosis causes neurogenic claudication, which is relieved by spinal flexion (e.g., leaning forward).
  • Most common disc herniations are L4-L5 and L5-S1.

Practice Questions: Spinal surgery fundamentals

Test your understanding with these related questions

A 65-year-old woman comes to the physician for the evaluation of sharp, stabbing pain in the lower back for 3 weeks. The pain radiates to the back of her right leg and is worse at night. She reports decreased sensation around her buttocks and inner thighs. During the last several days, she has had trouble urinating. Three years ago, she was diagnosed with breast cancer and was treated with lumpectomy and radiation. Her only medication is anastrozole. Her temperature is 37°C (98.6°F), pulse is 80/min, respirations are 12/min, and blood pressure is 130/70 mm Hg. Neurologic examination shows 4/5 strength in the left lower extremity and 2/5 strength in her right lower extremity. Knee and ankle reflexes are 1+ on the right. The resting anal sphincter tone is normal but the squeeze tone is reduced. Which of the following is the most likely diagnosis?

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Flashcards: Spinal surgery fundamentals

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Patients with volkmann ischemic contracture have significant pain with _____ extension of fingers / wrist

TAP TO REVEAL ANSWER

Patients with volkmann ischemic contracture have significant pain with _____ extension of fingers / wrist

passive

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