Twin robotic x-ray system in small bone and joint trauma: impact of cone-beam computed tomography on treatment decisions

Abstract

Objectives: Trauma evaluation of extremities can be challenging in conventional radiography. A multi-use x-ray system with cone-beam CT (CBCT) option facilitates ancillary 3-D imaging without repositioning. We assessed the clinical value of CBCT scans by analyzing the influence of additional findings on therapy.

Methods: Ninety-two patients underwent radiography and subsequent CBCT imaging with the twin robotic scanner (76 wrist/hand/finger and 16 ankle/foot/toe trauma scans). Reports by on-call radiologists before and after CBCT were compared regarding fracture detection, joint affliction, comminuted injuries, and diagnostic confidence. An orthopedic surgeon recommended therapy based on reported findings. Surgical reports (N = 52) and clinical follow-up (N = 85) were used as reference standard.

Results: CBCT detected more fractures (83/64 of 85), joint involvements (69/53 of 71), and multi-fragment situations (68/50 of 70) than radiography (all p < 0.001). Six fractures suspected in radiographs were ruled out by CBCT. Treatment changes based on additional information from CBCT were recommended in 29 patients (31.5%). While agreement between advised therapy before CBCT and actual treatment was moderate (κ = 0.41 [95% confidence interval 0.35-0.47]; p < 0.001), agreement after CBCT was almost perfect (κ = 0.88 [0.83-0.93]; p < 0.001). Diagnostic confidence increased considerably for CBCT studies (p < 0.001). Median effective dose for CBCT was 4.3 μSv [3.3-5.3 μSv] compared to 0.2 μSv [0.1-0.2 μSv] for radiography.

Conclusions: CBCT provides advantages for the evaluation of acute small bone and joint trauma by detecting and excluding extremity fractures and fracture-related findings more reliably than radiographs. Additional findings induced therapy change in one third of patients, suggesting substantial clinical impact.

Key points: • With cone-beam CT, extremity fractures and fracture-related findings can be detected and ruled out more reliably than with conventional radiography. • Additional diagnostic information provided by cone-beam CT scans has substantial impact on therapy in small bone and joint trauma. • For distal extremity injury assessment, one-stop-shop imaging without repositioning is feasible with the twin robotic x-ray system.

Keywords: Cone-beam computed tomography; Extremities; Fractures, bone; Radiography.

Conflict of interest statement

Jan-Peter Grunz is a research consultant for Siemens Healthineers. The authors of this manuscript declare no further relationships with any companies, whose products or services may be related to the subject matter of the article.

Figures

Fig. 1

Flow chart for visualization of study inclusion/exclusion criteria, study population, and individual steps of the data analysis

Fig. 2

Display of the tableside scan position for wrist imaging with the twin robotic x-ray system

Fig. 3

A 55-year-old woman presented to the emergency department with radial-sided left wrist pain and swelling after slipping during yoga class. Initial radiography was deemed negative for fracture presence (a). Subsequent cone-beam CT demonstrated a subtle fracture line in the waist of the scaphoid bone (arrowhead), corresponding to a potentially unstable B2 fracture (b). Suggested treatment was upgraded to surgery; however, the patient decided for conservative therapy. MRI follow-up after 1 week confirmed the fracture diagnosis, depicting extensive bone bruise in the distal portion of the scaphoid (c)

Fig. 4

A 22-year-old male sprinter was admitted with increasing left ankle pain after an acute sprain in training. He was unable to bear weight on the left foot and stated pressure pain over the proximal first metatarsal. No fracture could be located in anteroposterior and lateral x-ray scans (a, b), whereas ensuing cone-beam CT depicted a medial avulsion fracture of the left navicular bone (c, d). Treatment was upgraded to cast immobilization

Fig. 5

After a fall on the outstretched hand, x-rays of a 63-year-old man exhibited a distal radius fracture with metaphyseal impaction (a). While articular surface affliction could not be ascertained in radiography, the cone-beam CT scan demonstrated involvement of the radiocarpal and distal radioulnar joint (b). Open reduction was advised irrespective of CT imaging and the reported impaction of the lunate fossa was corrected intraoperatively

Fig. 6

While unloading a truck, a 51-year-old man fell from approximately 2 m height onto his head and right hip. Also reporting right wrist pain, a simple non-displaced fracture of the radial styloid was surmised after radiography (a). Coronal reformatting of subsequent cone-beam CT (b) confirmed the suspected injury, whereas axial view (d) disclosed additional fracture lines in the articular surface of the distal radius. Coronal and axial multiplanar reconstructions of 3-D dual-echo steady-state MRI (c, e) validated cone-beam CT findings. Treatment was upgraded from immobilization to surgery