Advances in the Canine Cranial Cruciate Ligament, 2nd edition

158 Clinical Features

(A) (B)

Figure 21.3 Sagittal (A) SE

T2-weighted MR image of a

2-year-old, intact male Great

Dane and (B) dorsal SE

T1-weighted MR image of a

2.5-year-old, neutered female

Rottweiler. Note the linear,

high-SI band within the meniscus

(arrows) that are parallel to the

interface between meniscus and

synovial fluid that does not

extend to the articular surface.

Tendons, ligaments, and muscles

Tendons, ligaments, and muscles of the sti-
fle joint (Table 21.1; Figures 21.4–21.9), along
with bone conformation, restrict movement pri-
marily to a cranio-caudal plane with minimal
rotation and slide. Tendons and ligaments nor-
mally appear as homogeneous, low-SI, sharply
margined linear structures, and on cross-section
are round, oval, or flat (Rubin 2005; Soleret al.
2007). However, the quadriceps tendon, in con-
trast to the patellar tendon, may normally have

parallel hyperintense and hypointense linear

striations due to a coarse fiber pattern. A higher

SI may also be seen normally if muscle is inter-

spersed with the fibers, or if the orientation

of the fibers approaches 55◦ relative to the

magnetic field (magic-angle artifact) (Spriet &

McKnight 2009). During tendon degeneration

or ligament sprain the structure may have an

increased SI, an altered size (usually increased),

irregular margins, or abnormal shape (Rubin

2005; Stahlet al. 2010). With an acute tendon

or ligament tear, total discontinuity may be

Table 21.1 Key for Figures 21.4–21.9.

Anatomic structures

1. Femur


2. Patella


3. Tibia


4. Fibula


5. Lateral collateral ligament


6. Medial collateral ligament


7. Meniscofemoral ligament


8. Cranial cruciate ligament


9. Caudal cruciate ligament


10. Transverse ligament


11. Quadriceps muscle
    a. Vastus lateralis muscle
    b. Vastus intermedius muscle
    c. Rectus femoris muscle
    d. Vastus medialis muscle
    e. Quadriceps tendon
    f. Patellar tendon


12. Infrapatellar fat pad


13. Sartorious muscle
    a. Cranial
    b. Caudal


14. Biceps femoris muscle


15. Abductor cruralis caudalis muscle


16. Semitendinous muscle


17. Semimembranosus muscle


18. Gracilis muscle


19. Adductor muscle


20. Aponeurosis of pectineus muscle


21. Long digital extensor muscle
    a. Tendon


22. Extensor hallucis longus muscle


23. Fibularis longus muscle
    (formerly peroneus longus)


24. Lateral digital extensor muscle


25. Flexor hallucis longus muscle


26. Popliteus muscle
    a. Tendon
    b. Sesamoid bone


27. Cranial tibial muscle


28. Caudal tibial muscle


29. Long digital flexor muscle


30. Gastrocnemius muscle
    a. Fabella (sesamoid bone)
    b. Lateral head
    c. Medial head


31. Superficial digital flexor muscle