Knee Replacement & Neuropathy: Risks, Factors & Management

Total knee arthroplasty (TKA) is highly successful, but peroneal nerve palsy and other neuropathies occur in 0.3-4% of cases.

Mechanisms of Nerve Injury

• Direct trauma: Retractor placement, surgical instruments, cement extrusion.
• Stretch: Postoperative correction of valgus deformity stretches peroneal nerve (most common).
• Compression: Hematoma, tourniquet, positioning (fibular head against bed).
• Ischemia: Vascular compromise from tourniquet or hypotension.

Risk Factors

• Pre-existing neuropathy (diabetes, alcohol, chemo)
• Severe preoperative valgus (>15°)
• Major deformity correction
• Obesity (BMI >40)
• Rheumatoid arthritis
• Revision surgery
• Tourniquet time >120 min

Presentation

• Common peroneal nerve: Foot drop, sensory loss on dorsum of foot/lateral leg.
• Saphenous nerve: Medial leg/foot numbness (often from medial incision).
• Tibial nerve: Rare; plantar sensory loss, weakness.

Management

• Observation: Most neuropraxias recover in 3-12 months.
• AFO (ankle-foot orthosis): For foot drop during recovery.
• Physical therapy: Prevent contracture, maintain strength.
• EMG/NCS: At 6-8 weeks if no improvement; distinguishes neuropraxia vs. axonotmesis.
• Surgery: Rare; neurolysis or tendon transfer for permanent deficit.

Prevention

• Careful retractor placement, limb positioning, padding.
• Limit tourniquet time/pressure.
• Preoperative nerve assessment; counsel high-risk patients.

Discuss nerve injury risks with your surgeon during consent. Most are transient, but informed expectation improves satisfaction.