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CLINICAL REPORT
Myofascial Pain Syndrome Affecting the Quadratus Femoris Joan Dalmau-Carolà, MD, FIPP Pain Clinic, Girona, Catalonia, Spain
䊏 Abstract: The quadratus femoris is an external rotator of the hip. Quadratus femoris injury can accompany damage to the surrounding muscles. Guided by the clinical symptoms, the injection technique described here can facilitate accurate diagnosis in selected cases. 䊏 Key Words: quadratus femoris injection, myofascial pain
INTRODUCTION The external hip rotators form a functional unit; the muscles that make up this group are, from top (rostral) to bottom (caudal), the piriformis, superior gemellus, obturator internus, inferior gemellus, obturator externus, and quadratus femoris. The quadratus femoris has a close relationship with the muscles that originate proximally in the os ischii (ischial tuberosity).1 Several muscular components can be injured by similar mechanisms and clinical symptoms and signs frequently do not suffice to identify the injured muscle. Sometimes, stepwise local injection is necessary to identify the offending muscle.2 The injection technique described here facilitates accurate diagnosis in selected cases.
CASE REPORT A 32-year-old man presented with a 9-month history of complains of pain in the right gluteal area. He had been Address correspondence and reprint requests to: Joan Dalmau-Carolà, MD, FIPP, Pain Clinic, 17002, Bisbe Lorenzana Street, 39, 3-3, Girona, Catalonia, Spain. E-mail:
[email protected]. Submitted: September 25, 2009; Revision accepted: November 10, 2009 DOI. 10.1111/j.1533-2500.2009.00347.x
© 2010 World Institute of Pain, 1530-7085/10/$15.00 Pain Practice, Volume ••, Issue ••, 2010 ••–••
diagnosed with ischiogluteal bursitis by ultrasound at another center. The pain was unresponsive to nonsteroidal anti-inflammatory drugs (NSAIDS) and physiotherapy. Five months prior to presentation, the pain worsened with nocturnal pain that extended to the lower lumbar region. A new course of physiotherapy and osteopathy was unhelpful. The pain was elicited in the upright position and when pushing a weight. On physical examination, the patient had the full range of movement of the lumbar spine. External rotation of the right hip elicited the gluteal pain in the prone position. Palpation revealed localized tenderness of the more lateral aspect of ischial tuberosity at the posterior insertion of the adductor magnus. After obtaining informed consent, we performed an injection in “loco dolenti” (at the site of pain) to confirm the diagnosis. The patient was placed prone with the fluoroscope C-arm directed at his right buttock. We localized the target point on the most external part of the ischial tuberosity. After the skin was anesthetized, in a tunnel vision fashion bone was gently contacted with a 22-G spinal needle. The needle was then withdrawn 1 mm to 3 mm and 1 mL of iohexol-240 contrast agent was injected; the proximal and posterior insertion of the adductor magnus muscle was displayed. A solution containing triamcinolone (40 mg) in 5cc of 0.25% bupivacaine was then injected (Figure 1). Two weeks later, pain measured on a visual analog scale (VAS) was decreased by 60%. On examination, the pain was elicited with flexion-adduction-external rotation of the hip. A trigger point was found at the level of the quadratus femoris between the ischial tuberosity and the femur. We performed a selective quadratus femoris
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Figure 1. Posterioranterior fluoroscopic image of right hip shows iohexol contrast agent injected into adductor magnus muscle.
Figure 3. The hip external rotator muscles and the sciatic nerve (Design by Joan Dalmau-Arasanz MD).
DISCUSSION
Figure 2. Posterioranterior fluoroscopic image of right hip shows iohexol contrast agent injected into quadratus femoris muscle.
muscle injection in a similar way, aiming at the most internal part of the intertrochanteric crest. After the skin was anesthetized, a 22-G spinal needle was advanced in a gun barrel fashion until the bone was gently contacted. The needle was then withdrawn 2 mm, and 1 mL of iohexol-240 contrast agent was injected to confirm the correct intramuscular placement (Figure 2). Again, a solution containing triamcinolone (40 mg) in 5 mL of 0.25% bupivacaine was then injected. Two weeks later, pain measured on VAS had decreased 90%. The patient was prescribed a home program of stretching and strengthening exercises. At 2 years of follow-up, the patient remained pain-free.
The quadratus femoris (Figure 3), is the more caudal muscular component of the 6 hip external rotators: piriformis, superior gemellus, obturator internus, inferior gemellus, obturator externus, and quadratus femoris. The piriformis originates from the anterior surface of the sacrum and inserts into the upper part of the trochanter. Lying inferior to the piriformis, the obturator internus originates inside the obturator foramen and inserts into the trochanteric fossa laterally. The superior gemellus originates above the superior and external part of the obturator foramen; the proximal insertion of the inferior gemellus is below and external to the obturator foramen. Both muscles merge with the obturator internus to insert distally into the trochanteric fossa. The quadratus femoris and the obturator externus, more anterior, lie caudal to the inferior gemellus. The quadratus femoris originates from the lateral aspect of the ischial tuberosity and inserts into the intertrochanteric crest laterally; the obturator externus originates from the obturator foramen and its membrane and inserts into the trochanteric fossa laterally. The proximal insertions (Figure 4) of the semimebranosus, semitendinosus, and biceps femoris lie posterior to the insertion in the quadratus femoris in the ischial tuberosity, and the posterior and proximal insertion
Quadratus Femoris Injection in Myofacial Pain • 3
Figure 4. The hip external rotators and the surrounding muscle insertions (Design by Joan Dalmau-Arasanz MD).
of adductor magnus lays posterior inferior to the insertion of the quadratus femoris. One of the best known causes of buttock pain is the piriformis syndrome,3,4 involving injury to this external hip rotator muscle. We now know that this syndrome may hide the damage to other components of the external hip rotator group. The sciatic nerve crosses the piriformis but it is also closely related to the rest of the muscular complex. Our patient presented with pain related to the injury to the adductor magnus, a muscle surrounding the proximal insertion of the quadratus femoris. Local injection provided only 60% relief (VAS). After this, examination elicited a new trigger point in the quadratus femoris, which works together with the piriformis muscle. The quadratus femoris muscle tear is an uncommon cause of gluteal pain.5 Magnetic resonance imaging (MRI) may be helpful to rule out quadratus femoris tear6 although the detection of MRI abnormalities are a poor predictor of pain as abnormal findings are present in a high percentage of patients without pain.7 In our case, MRI might have provided more conclusive evidence of quadratus femoris involvement, however, we did not perform MRI. Clinical judgment is crucial, and selective injection can sometimes be helpful. In this case, the wellknown clinical picture of the piriformis syndrome8 was not present and the trigger point was more caudal.
Consequently, we elected selective injection to aid in diagnosis. Although it is possible to target the quadratus femoris near the ischial tuberosity, the proximity of the sciatic nerve increases the risk of nerve injury. Furthermore, the proximal insertion of the quadrates femoris is deeper than the proximal insertion of the adductor magnus, so this approach requires losing contact with the bone thus losing depth perception. The intertrochanteric crest is safer because is it more lateral, although a potential for nerve injury remains. Alternatively, the injection can also be done under ultrasound guidance;9,10 this technique seems safer because you can visualize the sciatic nerve. However, our approach using fluoroscopy, maintaining a straight path at the level of the intertrochanteric crest and advancing the needle in tunnel vision step by step, also seems reasonably safe. In our technique, touching the bone with the tip of the needle helps ensure accurate depth assessment. After the procedure, a tailored program of stretching and strengthening exercises is essential.11 In summary, it seems that aiming at the quadratus femoris with our approach could be a complementary diagnostic technique in some cases. With this technique we achieved a good outcome in this case. A program of stretching and strengthening exercises complemented the treatment.
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