Diagnosis and endoscopic release of the piriformis muscle under local anesthesia for piriformis syndrome

We developed a minimally invasive technique for releasing the piriformis muscle under endoscopic control for entrapment neuropathy of the sciatic nerve due to tension and contraction of the piriformis muscle. This is a technical report on minimally invasive arthroscopic release of the piriformis muscle. This surgical technique was performed in patients who fulfilled at least five of nine diagnostic criteria (Fig. 1) that we established and who did not respond to conservative therapy for 6 months or more. While a cavity was maintained using a disposable syringe (10 ml) with a cut tip, an arthroscope (4mm in diameter) was inserted at an oblique viewing angle of 30degrees, and the muscle was identified. The area from the musculotendinous junction to the muscle was gradually incised using a special scraper. Pain disappeared simultaneously with release of the piriformis muscle during operation. In this technique of releasing the piriformis muscle, an adequate cavity can be produced and maintained in a manner similar to that in the posterior endoscopic operation for intervertebral disc herniation. This technique is useful for reducing postoperative pain and allows an early return to society.