146 Clinical Features
Figure 20.9 Transverse image of a fracture of the
distal femur showing displacement of one of the
fragments, but no involvement of the trochlear groove.groove can be evaluated, and by using three-
dimensional images the rotation (curvature)
of the long bones can be appreciated (Fig-
ure 20.8A,B).
Traumatic lesions
In case of fractures, the number and size, the ori-
entation, and possible involvement of the artic-
ular surface can be evaluated (Figure 20.9).
With avulsion fractures, the origin of the
involved tendons can be determined, which
is not always possible on radiographs. CT is
very useful for detection of avulsion fractures
of the CrCL (Figure 20.10), the CaCL (Fig-
ure 20.11), the attachment of the m. extensor
digitorum longus (Figure 20.12) (Fitchet al.
1997) and the m. popliteus (Figure 20.13).
By using CTA, the status of these fragments
can be evaluated for surgical decision-making
(Figure 20.14).
Degenerative changes
By using CT, degenerative changes can be
detected at an earlier stage than with radiogra-
phy (Figure 20.15).
Neoplastic disorders
The extension of neoplastic processes can be
better evaluated with CT than with radiography
(Figure 20.16) (synovial cell sarcoma, primary
bone tumor, lipoma). By using intravenous con-
trast, the soft-tissue component can be better
evaluated. Biopsies can be performed under CT
guidance (Figure 20.17).Infection
In case of infection, the extension of the process
can be better evaluated than with radiographs
(Figure 20.18).Miscellaneous
In case of subchondral bone cysts, the commu-
nication of the cyst with the joint cavity can be
checked using CTA (Figure 20.19).Conclusions
CT is useful in every case where the superim-
position of bony structures needs to be avoided