A 38-year-old man presents with pain and paresthesias in the lateral aspect of the leg and dorsum of the foot after a prolonged squatting posture while gardening. On examination, foot drop and weakness of ankle dorsiflexion are noted. Which is the most common site of compression of the sciatic nerve and its branches in this clinical scenario?

Explanation

## Most Common Site of Common Peroneal Nerve Compression ### Clinical Presentation The patient's foot drop, weakness of ankle dorsiflexion, and sensory loss over the lateral leg and dorsum of foot are classic signs of **common peroneal (fibular) nerve palsy**. ### Anatomical Basis The common peroneal nerve is the most superficial and vulnerable branch of the sciatic nerve. It becomes particularly exposed as it winds around the **fibular head and neck** at the level of the knee joint. **Key Point:** The fibular head is the most common site of compression of the common peroneal nerve, accounting for >50% of all peroneal nerve palsies. ### Why This Location Is Vulnerable 1. Superficial course around the fibular neck 2. Minimal soft tissue protection 3. Tethered position between bone and skin 4. Exposed to external pressure (prolonged squatting, tight casts, prolonged crossing of legs) ### Comparison of Compression Sites | Site | Frequency | Mechanism | Clinical Features | |------|-----------|-----------|-------------------| | **Fibular head/neck** | Most common (>50%) | External pressure, trauma, prolonged posture | Foot drop, ankle dorsiflexion weakness | | Piriformis muscle | ~15-20% | Entrapment in piriformis syndrome | Sciatic nerve involvement, buttock pain | | Greater sciatic foramen | Rare | Pelvic pathology | Sciatic nerve involvement | | Popliteal fossa | Uncommon | Trauma, Baker's cyst | Distal nerve involvement | **High-Yield:** Fibular head compression is the most common cause of common peroneal nerve palsy in clinical practice. A simple history of prolonged squatting or leg crossing often elicits the diagnosis. **Clinical Pearl:** Patients with fibular head compression typically recover well with conservative management (removal of pressure, physiotherapy) within 6–12 weeks if no axonal degeneration has occurred. **Mnemonic:** **FIBULAR** — Frequently Injured By Lateral Anatomical Resistance (superficial position at fibular head makes it vulnerable).