Hall, AC 2009, 'Ultrasound imaging of finger tendons at the bedside in the emergency department: a pilot study to assess whether it is a feasible and useful investigation', MSc thesis, Southern Cross University, Lismore, NSW.
Copyright AC Hall 2009
The interplay of structures in the finger that facilitate movement is complex and not yet fully understood. Subtle finger injuries are often missed during the initial assessment in the Emergency Department, because clinical examination of the acutely injured hand can be difficult. The consequences of unrecognized finger injuries can be devastating for the patient. Ultrasound imaging of tendons is a useful investigative tool although little has been published regarding the reliability of finger tendon measurements. The overall objective of this project was to establish if bedside ultrasound imaging of tendons was possible and useful in the setting of acute injury. The project was divided into two studies.
In the first study, 65 apparently normal volunteers were scanned to allow the principal investigator to practise and refine the ultrasound technique. The dimensions of the Extensor Digitorum Longus and two flexor tendons combined (Flexor Digitorum Profundus and Flexor Digitorum Superficialis) were measured in both transverse and longitudinal sections. Fifteen of the volunteers had their left middle fingers scanned twice within 48 hours to establish the test to retest reliability of tendon measurement. The established scanning technique was simple to perform and the scans, including both static and real time images, were completed within five minutes. All volunteers were able to tolerate a full scan. Measurement of tendon width showed fair to good reliability (Intra class correlation [ICC] of flexor tendons = 0.66, ICC of extensor tendon = 0.54). However measurement of the depth of all the tendons was unreliable test to retest (ICC < 0.37).
In the second study, 30 patients who presented to the Emergency Department at Lismore Base Hospital with hand injuries were scanned for evidence of tendon injury and tendon gliding restriction. The patient’s ability to tolerate ultrasound examination was investigated. The scan findings were compared with the clinical findings and then to the operation report or to the patient’s self reported outcome, one month after injury.
Patients were willing to undergo ultrasound examination regardless of the extent of their injury. There was a significant difference (p = 0.04) in scan tolerance related to the site of injury with 50% of those with extensor surface injuries having completed scans in comparison to 36% with flexor surface injuries and 9.1% of finger tip injuries. Injury mechanism was not related to scan tolerance.
Excluding a partial tendon laceration was technically difficult due to the presence of anisotropy artefact. However, all complete tendon lacerations were successfully identified prior to surgery. The gliding of the tendons was easy to visualize and abnormal gliding was found to be a marker of tendon injury.
The overall results show that ultrasound imaging of finger tendons at the bedside in the Emergency Department is a feasible examination to perform. The addition of ultrasound examination, however, did not identify any cases of tendon injury not already suspected on routine clinical examination.
Therefore, this pilot study suggests that routine use of ultrasound examination to detect finger tendon injury in the Emergency Department setting will not prove to be a useful investigation. There may be a role for ultrasound as a screening tool as the gliding of normal tendons differed noticeably from the gliding of injured tendons. The presence of normal tendon gliding may be helpful in identifying those patients that are safe to be discharged from the Emergency Department without further evaluation.