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Background and Aims A 64-years-old female with a history of hypertension was scheduled for right knee arthroscopy due to ruptured meniscus. Postoperatively she received analgesic saphenous nerve blockade at the level of adductor canal.

Methods Following spinal anesthesia at L3-4 interspace, using 27G Whitacre needle and chloroprocaine, patient received analgesic nerve blockade at the level of adductor canal using 10ml of 0.25% levobupivacaine.

Results 24 hours post-surgery patient started to feel burning pain in the saphenous nerve dermatome below knee. Pain was sharp, localized around medial malleolus, provoked with leg movement and lasted couple of seconds. 20 days post-surgery pain was still present but diminished in frequency and intensity. EMNG of femoral and saphenous nerve showed absence of signal along saphenous nerve. Right leg MR showed intraneural edema in 11cm long segment from medial condyle downwards.

Conclusions Saphenous nerve entrapment as a consequence of regional anesthesia at the level of adductor canal has not yet been described in literature. Damage to the infrapatellar branch of saphenous nerve is known complication of knee arthroscopy but symptoms presented here did not correlate with infrapatellar branch injury, so the initial conclusion was that they originated from main branch entrapment. MR was able to precisely locate type and location of injury so it should be the method of choice in this type of injury. Assumption is that high tourniquet pressure entraps the nerve and prevents its additional axial, longitudinal mobility. In the case of additional leg movement after tourniquet placement, axial nerve extension injures the tourniquet entrapped nerve.