Four-dimensional computed tomography: musculoskeletal applications.

Four-dimensional computed tomography (4DCT), or dynamic CT, is an emerging modality with a wealth of orthopedic applications for both clinical practice and research. This technology creates CT volumes of a moving structure at multiple time points to depict real-time motion. Recent advances in acquisition technology and reduction in radiation dosage have allowed for increased adoption of the modality and have made imaging of joint motion feasible and safe. Musculoskeletal 4DCT has been used primarily to investigate wrist motion; however, the utility of 4DCT has been shown in other areas, including the shoulder, elbow, hip, knee and ankle. Imaging these joints through a full range of motion provides new insight into dynamic phenomena such as instability, impingement and joint kinematics. Although 4DCT has not yet been widely adopted in orthopedic practice and research, future use has the potential to enable a deeper understanding of musculoskeletal conditions and to improve patient care.