Tethered cord syndrome discovered in preoperative examination.

We present an instructive case of a 47-year-old female patient with tethered cord syndrome, discovered before arthroscopy was to be performed under routine spinal anesthesia for right knee arthritis. The patient had no symptoms except for right knee-joint pain, but weakness in the left dorsiflexors and decreased range of motion in the left ankle and toe joints were found on preoperative physical examination. In addition, clawfoot deformity was discovered in the left foot. A small stigma was observed on the skin in the sacral region. A magnetic resonance imaging scan showed the spinal cord tethered to an intrathecal mass in the sacral region. Therefore, we avoided spinal anesthesia. The arthroscopy proceeded uneventfully with the patient under general anesthesia.