Accuracy of sonographically guided intra-articular injections in the native adult hip

Objective. The purpose of this study was to determine the accuracy of sonographically guided intra-articular injections performed in the native adult hip using contrast-enhanced fluoroscopy as a reference standard. Methods. Twenty-eight consecutive patients (ages 32-91 years; mean, 68 years) referred to the pain clinic for intra-articular hip injections were recruited to participate. In each case, a 2- to 6-MHz curvilinear array transducer was used to place the needle into the hip joint at the femoral head-neck junction using an oblique sagittal approach. A contrast-enhanced fluoroscopic examination was then completed and assessed by an independent observer to determine needle placement accuracy. Once accurate placement was confirmed, the therapeutic injection proceeded. Results. Thirty hip injections were completed in 15 women and 13 men (1 man and 1 woman received bilateral injections). The patients' body mass index (BMI) ranged from 20 to 39 kg/cm² (mean, 28 kg/cm ²) and procedure time from initial scanning to injection averaged 112 seconds (range, 47-187 seconds). Overall, 97% of sonographically placed needles were accurate. The single inaccurate placement resulted from inadvertent needle withdrawal from the joint capsule during connection of the extension tubing for contrast agent injection in a young patient with a BMI of 28 kg/cm² and no hip effusion. Conclusions. Sonographic guidance can be used to inject the native adult hip joint with acceptable accuracy. When using the oblique sagittal approach, operators must be aware of the possibility of needle withdrawal from the joint due to the limited intra-articular space within the target region, particularly in the absence of effusion.