Feasibility of ultrasound examination in posterior ligament complex injury of thoracolumbar spine fracture.

STUDY DESIGN: A prospective study of 12 patients with thoracolumbar spinal fractures was conducted.

OBJECTIVE: To assess the feasibility of ultrasound examination for posterior ligament complex injury in thoracolumbar spinal fractures.

SUMMARY OF BACKGROUND DATA: In posterior ligament complex injury of thoracolumbar spine fracture, the reliability of magnetic resonance imaging (MRI) for diagnosis has been reported. Nevertheless the usefulness of ultrasound for diagnosis has not been studied, whereas diagnostic ultrasound has been applied in the musculoskeletal system.

METHODS: Two healthy volunteers without a history of spinal trauma were recruited for pilot examination of the ultrasound procedure to access normal findings of the posterior ligament complex. This study investigated 12 thoracolumbar spine fractures. Four were flexion distraction injury; six were stable or unstable burst fractures; and two were simple compression fractures. Osteoporotic spine fractures were excluded from this study. Ultrasound was performed over the injured area by an experienced musculoskeletal radiologist in addition to radiography and MRI. Five patients underwent operative procedures to stabilize the fractured spine. Imaging data and operative findings were correlated with ultrasound examination.

RESULTS: In the patients who did not undergo surgery, agreement in diagnosis between MRI and ultrasound was moderate (5 of 7). Difficulty evaluating ligament status was encountered when the region of interest was the lower thoracic level (T10, T11, T12) because of long overlapping spinous processes. In the patients who underwent surgery, correlation between MRI, ultrasound, and operative findings was excellent, especially in diagnosing the status of the supraspinous and interspinous ligaments. Nevertheless, it is impossible to visualize deep-seated structures (i.e., ligamentum flavum, deep muscles of the spine, and facet joint) with ultrasound.

CONCLUSIONS: This study demonstrated the excellent diagnostic ability of ultrasound to detect the status of the supraspinous and interspinous ligaments, especially in patients who undergo surgery. Although ultrasound examination appears to be less sensitive than MRI in predicting ligament status, the cost effectiveness of ultrasound and its use as an alternative to MRI in special situations (i.e., patients with pacemaker, ferromagnetic implant, or severe claustrophobia) should be emphasized. More clinical data concerning the sensitivity, specificity, and accuracy of ultrasound examination should be addressed in future studies.