Background/Purpose: Facet joint-mediated pain has been identified as a common cause of lumbar pain. Steroid injections are currently made to treat them, usually performed under fluoroscopy or Computed Tomography-guidance. Ultrasound (US) is also appropriate to locate facet joints and some authors showed efficacy of US-guided injections through a transversal approach. On a longitudinal view, facet joints are easy-to-identify as a series of lumps with the joint capsule appearing as a thin hypoechoic line covering the joint. Each lump corresponds to the inferior articular process of the superior vertebra overlying the superior articular process of the vertebra below it. Considering the good visibility of these joints and their capsule on the longitudinal view, we studied the feasibility of US-guided facet joint injections using a longitudinal inline approach.

Methods: Patients referred to our Rheumatology department to receive facet joint injections under fluoroscopy have been included. To realize the injection, we first located the accurate lumbar level on a longitudinal median view and facet joints have been identified placing the probe 2-3 cm away from the median line. The needle was inserted in the axis of the probe to reach the hypoechoic line corresponding to the capsule or, if not visible, the top of the lump. When we obtained the bone contact, iodinated contrast medium followed by cortivazol has been injected. Finally, we made a lumbar X-ray. The first objective was to assess the number of injections realized in front of the joint. For secondary objectives, we assessed the number of accurate arthrography, the duration of the procedure and the occurrence of adverse events. During the US examination, the visibility of the capsule and the presence of osteophytes have been collected.

Results: Thirty-eight patients have been included by two operators. We excluded four patients because of a poor visibility of the spinal structures. Mean age was 58.4 years (range, 30-82) and mean BMI was 25.2 kg/m² (range, 18-34). US showed osteophytes in 42% and the articular capsule was inconstantly visible (25%). One-hundred and forty-four injections have been performed and 141 X-ray analyzed. One-hundred and twenty-three injections (87%) have been correctly realized in front of the joint. However, a proper arthrography has been obtained in only 35 cases (25%). Mean procedure duration was 8.5 minutes for four injections. No complication occurred, six patients (18%) reported a transient pain exacerbation.

Conclusion: With a longitudinal inline approach, 87% of US-guided facet joint injections were realized in front of the joint. However, we obtained a correct arthrography in only 25%. The depth of the target-point, the inconstant visualization of the capsule and the obliquity of the needle probably explain this result.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ultrasound-guided-facet-joint-injections-through-a-longitudinal-approach/