Page 351 - Canine Lameness

19.4 Cranial Cruciate igament Disease 323

ligaments are taut during full extension, providing some additional stifle stability, which mini-
mizes the potential cranial drawer movement that can be elicited. Drawer testing should be per -
formed in flexion, because if only the craniomedial band is torn, drawer will be absent in
extension but present in flexion (since the caudolateral band is lax in flexion). When perform-
ing cranial drawer testing in a CCL- deficient stifle, the tibia will translate cranially relative to
the distal femur with a subjectively loose/sloppy end-feel (i.e. capsular end-feel) when maxi-
mum, cranial tibial displacement is reached. This is in contrast to puppies that frequently
display cranial drawer movement with a hard stop (distinct end-feel) once the maximum, cra-
nial displacement is reached (i.e. the intact CCL is engaged). This so-called “puppy drawer”
(Video 19.3) is normal and a similar finding can be observed in dogs with severe muscle atro -
phy. Dogs with tense pelvic limb muscles or chronic joint fibrosis on the other hand may have
diminished cranial drawer sign. The best way for the novice examiner to learn how to perform
the cranial drawer test is to learn on a dog under sedation. Technical pitfalls of this test include
eliciting normal tibial internal rotation and interpreting this as positive drawer.

Video 19.3

Puppy drawer. STIFLE REGION

The cranial tibial compression (or thrust) test is another test for detecting CCL tears. The test
mimics the craniocaudal instability which occurs during weight-bearing. This test is subjectively
easier to perform on awake, energetic, or tense dogs than the cranial drawer test. However, the
tibial compression test can be difficult to interpret for the novice examiner. This test can also be
done with the patient standing or recumbent. The limb is placed with the hock in a standing posi-
tion and the stifle fully extended. One hand is placed over the cranial distal thigh with firm pres-
sure to keep the knee in full extension. The index finger of this hand is placed on the tibial tuberosity
to palpate for abnormal movement and to allow replacing the tibia in a caudal position (in case any
tibial subluxation is present). The other hand is used to flex the hock only, while the stifle is main-
tained in extension (Figure 19.8). In a normal stifle, no movement should be observed; in a stifle
that is CCL deficient, the tibial tuberosity will displace cranially. With a partial tear, this movement
may only consist of a few millimeters, which can be easily missed by the untrained or inexperi-
enced examiner. Visualizing the movement can be difficult in obese, or dogs with long coats, which
is why simultaneous palpation of tibial movement should be performed with the index finger. In
dogs with complete tears, the movement may be as obvious as a complete buckling of the stifle and
gross cranial movement of the tibial tuberosity. Performing this test while the dog is sedated is very
helpful for learning, especially for visualizing subtle thrust in partial CCL tears. A technical pitfall
of the technique is failure to keep firm enough pressure on the femur, which simply results in stifle
flexion and is not a true positive tibial compression test.
In a minority of patients, particularly those that have more acute (i.e. lacking chronic fibrous
tissue that provides some stability) CCLD, a very obvious positive tibial compression test can be
observed when the tibia is rotated internally. This finding has been termed “pivot shift” and is
defined as abrupt, cranial tibial displacement of the joint when the tibia is internally rotated (Video
19.4). While this condition has been described as a “jerking lateral movement of the stifle” while
weight-bearing (Gatineau et al. 2011; Knight et al. 2017), pivot shift can also be detected during