The obturator internus (OI) muscle is important in adult chronic noninfectious pelvic,
perineal, gluteal, and retrotrochanteric pain syndromes. Evaluation and management
of these patients’ pain can be challenging because of the complex anatomy of this
region, broad differential diagnosis, and lack of specific physical examination findings.
Consequently, several clinicians have advocated the use of image guided injections to
assist in the accurate diagnosis of OI-related symptoms and provide symptomatic relief
to affected patients. We present 2 case series describing a novel fluoroscopically guided
contrast controlled transpectineal approach to intrapelvic OI injections. Unlike prior
fluoroscopically guided OI injection techniques, the approach described in the present 2
cases utilized multiple standard pelvic views, thus facilitating optimal needle positioning
in three-dimensional space. This technique utilized standard fluoroscopic pelvic views
to accurately measure needle depth within the pelvic cavity permitting the bulk of the
OI to be injected in a controlled and safe fashion. The first patient underwent a left
intrapelvic OI muscle injection with bupivacaine 0.25% and 40 mg methylprednisolone.
The average pre- and postprocedural visual analog pain scale scores were 5 out of 10 and
2 out of 10, respectively, with a self-reported 75% pain reduction. The second patient
underwent a right intrapelvic OI muscle injection with bupivacaine 0.25% and 40 mg
methylprednisolone. The average pre- and postprocedural visual analog scale scores were
8 out of 10 and 1 out of 10, respectively, with a self-reported 90% pain reduction. Larger
scale studies should be undertaken to evaluate the therapeutic efficacy and generalized
accuracy of this technique.
Key words: Obturator internus muscle, pelvic, perineal, gluteal, retrotrochanteric pain,
fluoroscopic, transpectineal
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