Microsurgical Needle Retention Does Not Cause Pain or Neurovascular Injury in a Rat Model

Area of Science:

• Biomedical Engineering
• Surgical Innovation
• Animal Models

Background:

• Retained surgical foreign bodies, particularly needles, are a clinical concern.
• While macro-needles can cause symptoms, the impact of microsurgical needles is less understood.
• Microsurgical needles have a smaller cutting surface area compared to macro-needles.

Purpose of the Study:

• To establish the first animal model for simulating microsurgical needle retention.
• To investigate the potential health and neurovascular effects of retained microsurgical needles in rats.
• To test the hypothesis that microsurgical needle retention is benign.

Main Methods:

• Male Sprague-Dawley rats were implanted with 8.0 or 9.0 needles near femoral vessels or underwent sham surgery.
• Weekly health assessments included body weight, condition, appearance, and behavior.
• Infrared thermography and post-mortem fluoroscopy were used to evaluate neurovascular compromise and needle visualization.

Main Results:

• No significant changes in cumulative health scores were observed across all groups.
• Infrared thermography showed no significant temperature differences between hindlimbs over 90 days.
• Needles (8.0 and 9.0) were recovered, but visualization on fluoroscopy varied, with smaller needles being less visible.

Conclusions:

• Microsurgical needle retention near neurovascular structures appears to be benign.
• Imaging for needles smaller than 8.0 may not be effective.
• Further research with larger animal models is recommended to explore microsurgical needle retention.