Accuracy and safety of dry-needle placement
Dry needling is a widely used treatment modality for myofascial pain including piriformis syndrome.
This study did not discuss the mechanism of dry needling or attempt to define the piriformis syndrome.
The study simply looked at whether the dry needle accurately inserted into the piriformis muscle and whether it avoided puncturing the sciatic nerve.
A physical therapist (PT) who had 15 years of experience in the musculoskeletal care and 7 years with dry needling was responsible for placing the needle into 19 cadaveric hips.
The PT used surface anatomy as described by Reichert (2011)* to locate piriformis. Then, using a standardized process, inserted the needle into the medial portion of the piriformis. In terms of needle size, 0.35 (diameter) x 75mm (length) were used on 15 hips and 0.35 (diameter) x 100 mm (length) needles were used in 4 hips. Once the needles were placed, the gluteus maximus was dissected down and reflected laterally to reveal the needle location.
The study found that 16 out of 19 needles reached the medial portion of the piriformis muscle. 2 of the 3 that missed were not inserted to a sufficient depth. The other needle that missed had sufficient depth but missed the piriformis muscle superiorly. The 3 needles that missed had the 75mm length. None of the needles punctured the sciatic nerve.
Regardless of the differing opinions surrounding dry-needling and piriformis syndrome, a PT was able to insert a needle in the medial piriformis with 84% accuracy and without sciatic nerve puncture using surface anatomy and a standardized process of needle insertion.
*Reference: Reichert R, Palpation techniques: surface anatomy for physical therapists. Stuttgart: Thieme (2011); p. 229–231.
> From: Kearns et al., J Man Manip Ther (2018-03-16 15:00:01) (Epub ahead of print). All rights reserved to Taylor & Francis Group. Click here for the online summary.