Intramuscular neural distribution of the obturator internus muscle regarding injective treatment.

[INTRODUCTION] The obturator internus muscle is frequently targeted for injective treatments such as botulinum toxin injections in the management of pain syndromes. However, there are controversies over injective method delivering injection to the muscle.

[METHOD] A method called modified Sihler's method was used to stain the OI muscle in 16 specimens to reveal the intramuscular neural distribution of the muscle.

[RESULT] The greatest intramuscular neural distribution was located on the 2/10-4/10 of the muscle in the medial edge of the obturator foramen (0/0) to the greater trochanter of the femur (10/10).

[CONCLUSION] The result suggests that botulinum neurotoxin should be delivered in the intrapelvic portion of the obturator internus muscle. As most of the extrapelvic portion of the obturator muscle is composed of a tendinous portion, it should be considered unsuitable as an injection site by medical professionals.