210 Surgical Treatment
will undergo the same degradation as the native
CrCL. The immune rejection of allografts or
prosthetic materials is a concern. Processing
of allografts, including deep-freezing, chemi-
cal treatment or decellularization, may decrease
this potential. Prosthetic graft replacements will
likely become more biocompatible as new mate-
rials are developed. With any graft, furtherin
vivoexperimental and clinical studies will be
needed in dogs to demonstrate the safety and
efficacy of any implanted intra-articular graft.
Future developments
Although extra-articular repairs continue to be
the most common surgical treatment for CR,
work should continue overcome the limitations
of extra-articular repairs and the challenges of
intra-articular repair identified in this chapter.
In the search for a suitable graft,in vitromechan-
ical testing has revealed that the entire patella
tendon and the DDFT allograft, when doubled
on itself, possess similar mechanical properties
to the native CrCL of a similar-sized dog (Haut
et al. 1992; Biskupet al. 2014b; Biskupet al.
2015). Fixation methods have also been eval-
uated, placing different grafts at the proximal
and distal attachment sites of the CrCL (Biskup
et al. 2015). Results have shown that secur-
ing a DDFT allograft with a medial femoral
cross-pin and tibial spiked washers and inter-
ference screws can mimic the mechanical prop-
erties of the native CrCL. Finally, a study eval-
uating the effect of decellularization on DDFTs
showed significant decreases in DNA content
upon histological and biochemical testing, but
no decrease in mechanical strength when com-
pared to unprocessed allografts (Baloghet al.
2016).
Two recentin vivostudies have evaluated
intra-articular grafts with positive outcomes.
Cooket al. 2015 assessed replacement of the
craniomedial band of the CrCL with a long
digital extensor graft in research dogs. The
outcomes were positive, including no progres-
sion of OA and continued stifle function. A
small pilot prospective cohort study evaluated
the feasibility of intra-articular CrCL repair in
dogs with naturally occurring CR (Biskupet al.
2017). Ten client-owned dogs with unilateral
CR underwent a repair using a decellularized
Figure 26.4 Intraoperative picture of an intra-articular
repair using a deep digital flexor allograft. A drill guide is
in position to drill the femoral tunnel.DDFT allograft placed at the femoral and tibial
attachment sites of the CrCL, and secured with
a medial femoral cross-pin and tibial spiked
washers and interference screws (Figure 26.4).
Owner questionnaire results showed improve-
ment throughout the study, with the greatest
improvement over the first 6 months. Similarly,
peak vertical force and vertical impulse were
improved throughout all time points, with a
continued upward trend at 12 months. Radio-
graphs revealed minimal progression of OA.
Mild subluxation was present in multiple dogs
on both orthopaedic examination and weight-
bearing radiographs. Notably, caution must be
taken when drawing conclusions from these
studies, given the small population size and the
fact that no direct treatment comparison was
performed (Figure 26.5). One critical limitation
was that graft integrity was not documented in
the pilot project. One possibility is that periar-
ticular fibrosis may have contributed to clinical
outcome, although its contribution may be lim-
ited with intra-articular repairs (Hartet al. 2003).Conclusions
Intra-articular repair in veterinary medicine
continues to be inferior to extra-articular