Correct Answer: C. Foot drop
Foot drop is the most common postpartum nerve injury, occurring in approximately 1 in 2,000–3,000 deliveries in India. The common peroneal nerve is injured as it winds around the neck of the fibula just below the knee. During prolonged labour, especially with lithotomy position, forceps delivery, or prolonged squatting, the nerve is compressed against the fibula head by the leg supports, stirrups, or maternal positioning. This results in foot drop due to paralysis of the tibialis anterior muscle, preventing dorsiflexion of the foot. The patient presents with inability to lift the forefoot, causing a characteristic "steppage gait" where the foot drags during walking. Unlike other postpartum nerve palsies (brachial plexus, facial), common peroneal nerve injury is purely motor and superficial, making it the most frequently encountered. Recovery is usually good within 6–12 weeks with conservative management and physiotherapy, as the nerve compression is typically neuropraxia rather than axonotmesis. Prevention involves avoiding prolonged lithotomy position, proper padding of leg supports, and avoiding excessive hip flexion during labour.
Why the other options are wrong
A. Claw hand — Claw hand results from ulnar nerve injury (intrinsic hand muscles) or combined median-ulnar injury, which is extremely rare postpartum. The ulnar nerve is not exposed to compression during labour or delivery. This is a trap for students who confuse postpartum nerve injuries with general nerve palsies without considering obstetric anatomy and positioning. B. Facial palsy — Facial nerve palsy postpartum is rare (1 in 2,500–5,000 deliveries) and usually results from forceps trauma to the facial nerve trunk or prolonged compression against the maternal pelvis. While it does occur, it is significantly less common than common peroneal nerve injury. Students may overestimate its frequency because facial palsy is a classic teaching point in obstetrics. D. Wrist drop — Wrist drop indicates radial nerve injury, which is extremely rare postpartum. The radial nerve is not compressed during normal labour or delivery mechanics. This option may trap students who recall radial nerve palsy from other contexts (e.g., Saturday night palsy, fracture humerus) and incorrectly apply that knowledge to obstetric nerve injuries.
High-Yield Facts
- Common peroneal nerve injury is the most common postpartum nerve palsy (1 in 2,000–3,000 deliveries), caused by compression against the fibula head during lithotomy position or forceps delivery.
- Foot drop with steppage gait is the classic presentation; tibialis anterior paralysis prevents dorsiflexion of the foot.
- Lithotomy position and prolonged labour are the primary risk factors; proper padding of leg supports and avoiding excessive hip flexion are preventive measures.
- Prognosis is excellent; most cases recover within 6–12 weeks as the injury is typically neuropraxia (conduction block) rather than axonal damage.
- Facial nerve palsy (1 in 2,500–5,000) and brachial plexus injury are far less common postpartum nerve injuries than common peroneal nerve injury.
Mnemonics
LITHO-FOOT (Postpartum Nerve Injury Frequency) Lithotomy → Foot drop (common peroneal); Forceps → Facial palsy (rare); Brachial plexus (very rare). The most common injury follows the most common position. FIBULA-FOOT Memory Hook Peroneal nerve wraps around FIBULA → compression in lithotomy → FOOT drop. The anatomical relationship makes it the most vulnerable nerve in obstetrics.
NBE Trap
NBE may pair "facial palsy" as a distractor because it is a classic obstetric complication taught prominently in textbooks, leading students to overestimate its frequency relative to the much more common common peroneal nerve injury. The question tests knowledge of epidemiology, not just recognition of nerve palsies.
Clinical Pearl
In Indian obstetric practice, where prolonged labour and instrumental delivery remain common due to limited access to timely caesarean sections in rural areas, foot drop is frequently encountered in the postpartum ward. Early recognition and physiotherapy initiation within the first week can prevent contractures and accelerate recovery, making this a high-yield bedside skill for obstetricians and gynaecologists.
_Reference: DC Dutta's Textbook of Obstetrics (7th ed.), Ch. 24 (Complications of Labour); Bailey & Love's Short Practice of Surgery, Ch. 58 (Obstetric Surgery)_