Multi-detector computed tomography (MDCT) diagnostics in total knee arthroplasty: Comparison of different MDCT protocols

The prevalence of osteoarthritis as a degenerative disease of the knee is constantly increasing. Nearly 30% of individuals greater than 45 years old have radiographic evidence of knee osteoarthritis. The total knee arthroplasty (TKA) is the method of choice for the treatment of advanced osteoarthritis. It represents a surgical procedure in which three articular surfaces of the knee are replaced by the placement of three appropriate prosthetic components. It is estimated that the number of TKA procedures will increase by 673% between 2005 and 2030. There is a definite connection between the accuracy of the implant position and the long-term durability of the prosthesis. Multidetector computed tomography (MDCT) diagnosis, according to the "Perth CT protocol" in addition to the methods of conventional, "long-leg" radiography and CT scans, provides the best available means for adequate assessment of alignment. It involves CT examination of the limb from the roof of the acetabulum to the talus arch, in supination, neutral position of the leg and maximum knee extension. Post-procedurally, by reformation in the coronal, sagittal and axial planes, seven alignment characteristics, the mechanical and anatomical axis of the leg are determined. The effective dose of radiation at long-leg radiography is about 0,7 mSv, and for MDCT examinations according to the Perth CT protocol about 2,7 mSv. Henckel and collaborators devised a low-dose CT protocol (Imperial) that achieved a total radiation dose between 0,53 and 0,84 mSv, which is approximately the X-ray dose, and involved separate imaging of the leg at the level of the hip, knee, and ankle while changing certain parameters acquisitions.