Sensibility and cutaneous reinnervation in free flaps

Area of Science:

• Plastic Surgery
• Neuroscience
• Regenerative Medicine

Background:

• Free flap transfers are crucial for reconstructing lower extremity defects.
• Assessing sensory recovery after these procedures is vital for functional outcomes.
• Understanding reinnervation patterns informs surgical techniques and patient expectations.

Purpose of the Study:

• To investigate the extent and nature of sensory reinnervation in free flaps on lower extremities.
• To correlate sensory recovery with time elapsed since flap transfer.
• To identify the pathways (superficial vs. subcutaneous) involved in sensory reinnervation.

Main Methods:

• Evaluated 19 patients with free flaps on lower extremities.
• Assessed sensibility using tests for deep pressure, superficial modalities, and heat pain thresholds.
• Examined flap tissue for neurofilament-positive sensory nerve fibers via histology.

Main Results:

• All patients exhibited deep pressure sensibility.
• 10 patients demonstrated heat pain sensitivity (threshold ~50°C), particularly those examined later.
• No superficial sensory modalities were detected; nerve fibers were absent in dermis/epidermis but present subcutaneously in one case.

Conclusions:

• Deep pressure sensibility is achieved early after free flap transfer.
• Heat pain sensitivity develops in most patients, likely due to subcutaneous reinnervation.
• Superficial sensory reinnervation is generally absent in these free flaps.