Correlation of ultrasound-guided corticosteroid injection of the quadratus femoris with MRI findings of ischiofemoral impingement.

OBJECTIVE: MRI findings of ischiofemoral impingement (IFI) have been described, but there is little evidence for treatment with ultrasound-guided corticosteroid injection. The purpose of this study was to evaluate the effectiveness of ultrasound-guided corticosteroid injection of the quadratus femoris muscle as a treatment of IFI syndrome and to correlate the MRI findings with injection outcome.

MATERIALS AND METHODS: The medical records of 61 consecutively registered subjects who underwent bony pelvis MRI in which either IFI or quadratus femoris edema was described in the radiology report were retrospectively reviewed. Subjects with MRI findings of IFI and clinical confirmation of pain that could be attributed to IFI were included and divided into injection and control groups based on clinical management. Control subjects had MRI findings and clinical symptoms suggestive of IFI but underwent conservative therapy rather than injection. The control patients had adequate follow-up and clinical documentation to determine their response to treatment. Quadratus femoris muscle edema, fat atrophy, and hamstring tendinopathy were graded from none to severe (grades 0-3). The ischiofemoral and quadratus femoris spaces were also measured. Clinical presentation was classified as typical, somewhat typical, or not typical of IFI. Injection effectiveness was determined by reported pain reduction assessed before, immediately after, and 2 weeks after the procedure with a standard 10-cm visual analog scale. Response to treatment was classified as good (reduction in pain level > 2), mild or partial (reduced by 1 or 2), or no improvement. For patients who did not return their 2-week postinjection pain surveys, injection effectiveness was determined by qualitative assessments found in their clinical notes. A Kruskal-Wallis rank sum test was used to compare effectiveness of injection between groups (p < 0.05). The Fisher exact test was used to evaluate for associations between each MRI finding and injection outcome.

RESULTS: Of the 61 patients, 20 patients had both MRI findings and clinical confirmation of pain related to IFI. These 20 patients were included in the study. Fifteen ultrasound-guided injections were performed in seven patients, and these seven patients were included in the injection group (mean age, 47 years; range, 15-66 years); 13 patients were included in the control group (mean age, 42 years; range, 16-62 years). All seven patients in the injection group and 12 of the 13 patients in the control group were women. In the injection group, the mean width of the ischiofemoral space was 12 mm (range, 7-22 mm), and the mean width of the quadratus femoris space was 9 mm (range, 5-16 mm). The mean edema grade was 1.4 (range, 0-3); mean atrophy grade, 1.4 (range, 0-3); and mean hamstring tendinopathy grade, 1 (range, 0-2). In the control group, the mean width of the ischiofemoral space was 9 mm (range, 6-17 mm); mean quadratus femoris space width, 7 mm (range, 3-15 mm); mean edema grade, 1.9 (range, 1-3); mean atrophy grade, 1.2 (range, 0-3); and mean hamstring tendinopathy grade, 1.2 (range, 0-3). No statistical difference was seen between the two groups before treatment. Pain reduction after injection over the 2-week period was statistically significant with a mean reduction of 1.7 (range, 1-2) for the injection group and 0.8 (range, 0-2) for the control group (p < 0.01). Eleven of 15 (73%) of the injections provided good relief, and four of 15 (27%) provided mild relief. None of the 15 injections provided no relief. In the control group, four of 14 (29%) subjects had good relief, three of 14 (21%) had mild relief, and seven of 14 (50%) had no relief (p < 0.01).

CONCLUSION: Ultrasound-guided corticosteroid injection of the quadratus femoris muscle shows promise as an effective treatment of IFI syndrome. However, larger longitudinal studies are needed to help establish the role of ultrasound-guided injection in the workup and care of patients presenting with both MRI findings and clinical findings of IFI.