During lithotomy or lateral positioning, which nerve injury is a risk and how can it be mitigated?

• A. Ulnar nerve injury; mitigate with padding, leg positioning, and avoiding compression.
• B. Median nerve injury; mitigate with padding.
• C. Peroneal (common fibular) nerve injury; mitigate with proper padding, leg positioning, and avoiding compression.
• D. Sciatic nerve injury; mitigate with leg elevation.

Answer: (C)

In these positions, nerves can be endangered by pressure and misalignment, especially when parts of the leg are held in place for long periods. The common fibular (peroneal) nerve sits just under the skin at the fibular head, making it unusually vulnerable to compression from leg supports, stirrups, padding, or direct pressure when the legs are flexed in lithotomy or are held in a dependent position in lateral setup. Pressure here can disrupt nerve function and later cause difficulty with ankle dorsiflexion (foot drop) and numbness on the top of the foot.

To prevent this, focus on relieving and distributing pressure in the lower leg: apply adequate padding over the fibular head, use leg supports that spread pressure away from the fibular neck, and ensure the legs aren’t excessively flexed or externally rotated. Recheck and adjust positioning periodically during long cases to avoid prolonged compression. In the lateral position, protect the dependent leg with proper padding and avoid placing pressure directly against bony prominences.

Thus, protecting the common fibular nerve through padding and careful leg positioning is the key preventive measure in lithotomy or lateral positioning.