Advances in the Canine Cranial Cruciate Ligament, 2nd edition

Arthroscopic Follow-Up after Surgical Stabilization of the Stifle 281

CrCL

MFC

MM

Figure 33.2 The cartilage of the medial femoral condyle
(MFC) and tibial plateau and the medial meniscus (MM)
appear healthy in dogs with early partial tears of the CrCL
at follow-up arthroscopy.

axis, cranial tibial thrust is transformed to a
caudal tibial thrust (Warzeeet al. 2001; Reifet al.
2002). Eliminating cranial tibial thrust would
likely lower strain within the CrCL, reducing
the possibility of further fiber tearing. This
supports other clinical work which suggests
that TPLO has a protective effect on the CrCL
in dogs having an early partial CR (Wolfet al.
2008). As such, the authors do not recommend
the debridement of intact functional CrCL
fibers due to good functional outcome and the
potential protective effect on the menisci and
cartilage. The articular cartilage of the femur
and tibia, the medial and lateral menisci, and
synovial joint capsule all appeared normal in all
joints in this group of dogs (Figure 33.2). These
observations were true at 4 years after surgery,

the longest interval from initial surgery to

second-look arthroscopy in this group of dogs.

Conversely, the majority of dogs with a par-

tial tear with an incompetent remaining CrCL

and cranial drawer or a completely ruptured

CrCL ligament had significant intra-articular

changes. Of interest were articular cartilage

lesions involving the medial or lateral femoral

condyle or tibial plateau (Figure 33.3). Lesions

included chondromalacia, fibrillation, and ero-

sion (Figure 33.4). The lesions may arise from

abnormal joint contact mechanics or increased

contact with cranial soft tissue after rotation

of the tibial plateau to eliminate cranial tibial

thrust. Some 85% of the stifles in this group

(39/46) had visible cartilage lesions, with the

majority (28/39 stifles) having Grade 3 or Grade

4 lesions (see Bealeet al. 2003 for grading sys-

tem). Cartilage lesions appeared in the medial

femoral condyle (13 joints), lateral femoral

condyle (12 joints), and tibial plateau (three

joints) (Figure 33.5). Abaxial non-articular car-

tilage abrasion was most common, but axial

lesions of the weight-bearing surface were also

noted (Figures 33.6 and 33.7). In most dogs, mild

fraying of the CaCL was noted; in three dogs

there was complete rupture of the CaCL. In

one of these three dogs there was over-rotation

of the tibial plateau at revision surgery (ini-

tial postoperative slope 6◦; postoperative slope

after revision 0◦); in the other two dogs the tibial

plateau was rotated to 7◦in one case and to 10◦

in the other case. The history and acute nature

of lameness in the latter two dogs was sugges-

tive of a traumatic episode. Eight dogs devel-

oped a bucket-handle tear in the caudal horn

of the medial meniscus (postliminary meniscal

MFC

MFC

MM

TP MM

(A) (B)

TP

Figure 33.3 (A) The cartilage of
the medial femoral condyle (MFC)
and tibial plateau (TP) and the
medial meniscus (MM) appear
normal at the time of tibial plateau
leveling osteotomy in this patient
with an unstable partial CrCL tear.
(B) The cartilage of the MFC and TP
has fibrillation at the time of
follow-up arthroscopy in this
patient 12 months later. The medial
meniscus also has small radial tears.