Advances in the Canine Cranial Cruciate Ligament, 2nd edition

120 Clinical Features

Table 16.1 Results of partial and total sectioning of the canine cranial cruciate ligament (CrCL).

Degree of stifle flexion from maximal extension

0 ◦ 20 ◦ 40 ◦ 60 ◦

Cranio-medial component cut (n=5) 1.5 (0,2) 2 (2,3) 1 (1,2.5) 1 (0,1)

Caudo-lateral component cut (n=5) 0 (0,1.5) 1 (1,1) 0.5 (0,1) 0 (0,0)

Whole CrCL cut (n=10) 7.7±3.4 13.0±1.4 10.4±2.0 7.6±1.6

Note: Results represent cranial translation of the tibia relative to the femur in millimeters. For the whole CrCL cut, data
represent mean±standard deviation. For the other two experiments, data represent median (range). Source: Heffron &
Campbell 1978. Reproduced with permission from the British Veterinary Association.

objectively measure cranial tibial translation
may further aid in the early diagnosis of canine
partial CR.
Clinically, diagnosis of partial rupture of
the CrCL (Grade I sprain) should be limited
to dogs that are determined to have a stable
stifle with no cranial drawer or cranial tibial
thrust. The detection of cranial drawer motion
in only partial flexion is not a reliable indicator
of disruption to only the cranio-medial compo-
nent of the CrCL (Scavelliet al. 1990). During
cranial drawer testing of the stifle, a soft stop
to the test can be detected with minimal to
no cranial translation of the tibia. This clinical
finding reflects more severe matrix damage to
the CrCL (Grade II sprain). Although it has
been previously questioned whether a lack
of cranial drawer motion during the physical
examination of dogs with partial CrCL rupture

may be a consequence of periarticular fibrosis

(Scavelliet al. 1990), some degree of clinical

instability is typically found in dogs with

chronic CR (Tashmanet al. 2004).

Radiographically, stifle synovial effusion and

osteophyte formation are important signs that

support the diagnosis of partial CR. Even sub-

tle radiographic change should be considered

clinically important (Chuanget al. 2014). CrCL

fiber damage can be inferred from degenerative

changes radiographically (Sampleet al.2017).

The increasing use of arthroscopy to examine

the stifle joint of dogs with mild arthritis and

a clinically stable stifle suggests that superficial

fraying of the CrCL and the caudal cruciate liga-

ment (see also Chapter 17), superficial and deep

splits in the ligament tissue, and fiber rupture

are typically seen in the early phase of the con-

dition (Figure 16.1) (Bleedornet al. 2011).

(A) (B) (C)

Figure 16.1 Arthroscopic images of the intercondylar notch region of the distal femur of three dogs with partial cranial
cruciate ligament (CrCL) rupture. No cranial drawer or cranial tibial thrust was evident on physical examination. All of
the dogs had complete contralateral cruciate ligament rupture and an unstable stifle. Disruption of fibers or fiber bundles
is evident in the CrCL (arrows) (A,B). Splits in the fiber bundles often become more evident when examined with an
arthroscopic probe (C). Inflammation of adjacent synovium is typically evident (A). Ruptured fiber bundles often have a
pale yellow appearance (B). Thickening of the ends of torn fibers suggests a healing response that is not successful at
repair and remodeling of fiber bundles (∗). In this regard, the surrounding synovial fluid is known to promote fibrinolysis
of any provisional scaffold for repair of fiber damage. Right stifle (A,B), left stifle (C). CaCL, caudal cruciate ligament.