Total ankle arthroplasty: optimizing computed tomography imaging protocol

• Published in: Skeletal radiology Vol. 42; no. 11; pp. 1507 - 1513
• Main Authors: Kohonen, Ia, Koivu, Helka, Vahlberg, Tero, Larjava, Heli, Mattila, Kimmo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-11-2013; Springer; Springer Nature B.V
• Subjects: Animals; Ankle Joint - diagnostic imaging; Ankle Joint - surgery; Arthroplasty, Replacement, Ankle - methods; CT imaging; Diagnostic imaging; Humans; Imaging; Implants, Artificial; In Vitro Techniques; Medical imaging equipment; Medicine; Medicine & Public Health; Nuclear Medicine; Orthopedic surgery; Orthopedics; Pathology; Patient Positioning - methods; Prosthesis; Radiographic Image Enhancement - methods; Radiology; Reproducibility of Results; Scientific Article; Sensitivity and Specificity; Surgery, Computer-Assisted - methods; Swine; Tomography, X-Ray Computed - methods; Computed tomography; Total ankle arthroplasty; Metal artifact
• ISSN: 0364-2348; 1432-2161
• DOI: 10.1007/s00256-013-1692-6

Objective
To evaluate parameters and positioning when imaging total ankle prostheses on computed tomography (CT).
Materials and methods
An ankle prosthesis implanted into a pig’s knee joint underwent 16 different CT imaging protocols. Four defects were drilled around prosthesis components simulating periprosthetic osteolytic lesions. The specimen with the implant was imaged in four different orientations with the tibial stem parallel to the table and at 25, 45, and 90° angles to it. The protocol consisted of scanning at 100, 120, and 140 kVp in every position with a pitch of 1.2. The scanning at 120 kVp in every position was repeated with a pitch of 1.0.
Results
CT proved to be a reliable imaging modality when studying periprosthetic lesions adjacent to the ankle prosthesis when the tibial stem alignment was parallel to the table. When imaging at higher angles, metal artifacts distorted the image, making the analysis of periprosthetic bone structure unreliable. There were no statistically significant differences between different tube voltages or pitch in volume measurements of the osteolytic lesions.
Conclusions
CT is a reliable imaging method to evaluate periprosthetic bone structure around ankle prostheses when orientation of the prosthesis and acquisition parameters is optimized.