Electromagnetic field-based image-guided spine surgery part two: results of a cadaveric study evaluating thoracic pedicle screw placement.

Spine · 2003 · Mixed · Low evidence

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MixedLow evidencePaper 5261

Study snapshot

PublicationSpine · 2003

Study typeother

Reported directionMixed

Evidence ratingLow

Abstract

STUDY DESIGN: Human cadaveric. OBJECTIVES: Compare the accuracy of electromagnetic field (EMF)-based image-guided thoracic pedicle screw insertion to conventional techniques using anatomic landmarks and fluoroscopy. BACKGROUND: Image-guided surgical systems that aid in spinal instrumentation seek to minimize radiation exposure and improve accuracy. EMF image guidance was developed as an alternative to optical tracking to eliminate potential line of sight issues. MATERIALS AND METHODS: Four fresh-frozen human cadavers were randomly allocated into two groups. Pedicle screws were inserted from T1 to T12 using anatomic landmarks and fluoroscopy in group 1 and image guidance in group 2. Insertion and fluoroscopy time were recorded. Anatomic dissections were performed to assess screw placement. RESULTS: Image guidance placed 92% of thoracic pedicle screws safely, and conventional fluoroscopy placed 90% safely. The average degree of perforation was 2.4 mm with conventional fluoroscopy and 1.7 mm with image guidance (P = 0.055). Fluoroscopic time per screw was 5.9 seconds for conventional fluoroscopy and 3.6 seconds for image guidance (P = 0.045). Insertion time per screw was 4.35 minutes for conventional fluoroscopy and 2.98 minutes for image guidance (P = 0.007). However, when set-up time and image capture time were taken into account, the total insertion time per screw was not significantly different between the two groups. CONCLUSIONS: Our study has shown that EMF image-guided thoracic pedicle screw placement results in a similar incidence of safely placed screws as does conventional fluoroscopy. When set-up time and image-capture time were factored in for image guidance, the average time to insert a pedicle screw was equal for both techniques. The use of EMF image guidance significantly reduced fluoroscopic time and thus radiation exposure per screw compared with conventional fluoroscopic techniques.

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AI evidence extraction

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Study typeother

Effect directionmixed

PopulationHuman cadavers (fresh-frozen)

Sample size4

ExposureNot supplied

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

In a cadaveric comparison (T1–T12), EMF-based image guidance placed 92% of thoracic pedicle screws safely versus 90% with conventional anatomic landmarks/fluoroscopy. Mean perforation was 1.7 mm with image guidance vs 2.4 mm with conventional fluoroscopy (P=0.055). Fluoroscopy time per screw was lower with image guidance (3.6 s vs 5.9 s; P=0.045), and insertion time per screw was shorter (2.98 min vs 4.35 min; P=0.007), but total insertion time per screw was not significantly different after including setup and image capture time.

Outcomes measured

Accuracy/safety of thoracic pedicle screw placement
Degree of pedicle wall perforation (mm)
Fluoroscopy time per screw
Insertion time per screw
Total insertion time per screw (including setup and image capture)
Radiation exposure (inferred via fluoroscopic time)

Limitations

Cadaveric study (not living patients)
Small sample size (4 cadavers)
Exposure characteristics of the EMF system (frequency, field strength, SAR) not reported
Radiation exposure not directly measured; inferred from fluoroscopy time

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "electromagnetic field (EMF)-based image-guided surgical system",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Human cadavers (fresh-frozen)",
  "sample_size": 4,
  "outcomes": [
    "Accuracy/safety of thoracic pedicle screw placement",
    "Degree of pedicle wall perforation (mm)",
    "Fluoroscopy time per screw",
    "Insertion time per screw",
    "Total insertion time per screw (including setup and image capture)",
    "Radiation exposure (inferred via fluoroscopic time)"
  ],
  "main_findings": "In a cadaveric comparison (T1–T12), EMF-based image guidance placed 92% of thoracic pedicle screws safely versus 90% with conventional anatomic landmarks/fluoroscopy. Mean perforation was 1.7 mm with image guidance vs 2.4 mm with conventional fluoroscopy (P=0.055). Fluoroscopy time per screw was lower with image guidance (3.6 s vs 5.9 s; P=0.045), and insertion time per screw was shorter (2.98 min vs 4.35 min; P=0.007), but total insertion time per screw was not significantly different after including setup and image capture time.",
  "effect_direction": "mixed",
  "limitations": [
    "Cadaveric study (not living patients)",
    "Small sample size (4 cadavers)",
    "Exposure characteristics of the EMF system (frequency, field strength, SAR) not reported",
    "Radiation exposure not directly measured; inferred from fluoroscopy time"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "electromagnetic field",
    "EMF",
    "image-guided surgery",
    "spine surgery",
    "thoracic pedicle screw",
    "fluoroscopy time",
    "radiation exposure",
    "cadaveric study"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1097/01.brs.0000086822.76638.76
PubMed: 12973162

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