Front Matter

Chapter 11 Veterinary Orthotics and Prosthetics 267

3‐D modeling, and 3‐D printing simplifying
product development. Unfortunately, inno­
vation is outpacing science. A search of the
scientific literature, also in January of 2017,
revealed 16 V‐OP papers, six of which were
related to equine patients (shoeing practices),
three were small animal review articles
(Adamson et  al., 2005; Mich, 2014; Marcellin‐
Little et al., 2015), five were canine case reports
or case series (Levine & Fitch, 2003; Case, 2013;
Hardie & Lewallen, 2013; Tomlinson et al., 2014;
Carr, 2016), one survey (Hart et al., 2016), and one
computer simulation of stifle orthosis for canine
cranial cruciate ligament (CCL) insufficiency
(Bertocci et  al., 2017). Interestingly, the earliest
report was the use of an orthotic treatment for
tibiotarsal deformity in an elephant (Siegel, 1973).
A study of client satisfaction with one type of
CCL orthosis as compared with tibial plateau lev­
eling osteotomy indicated high client satisfaction
for both interventions (Hart et al., 2016). There is
anecdotal evidence for the use of these devices,
but there is a clear deficit in terms of evidence‐
based documentation of efficacy and a need for
more publications to advance the field.
The literature on prosthetic limbs has focused
on osteointegration as a means of supplanting
the socket‐based prosthesis for human patients
(Drygas et  al., 2008; Fitzpatrick et  al., 2011;
Devasconcellos et al., 2012). From the standpoint
of basic science, there is an upsurge in the
evaluation of canine limb dysfunction/loss
pathomechanics; this may drive future
controlled clinical trials as we begin to under­
stand the quality of life implications of such
injuries. The old maxim that “dogs do great on
three legs” is being scrutinized and may prove a
gross overstatement (Kirpensteijn et  al., 1999;
Abdelhadi et  al., 2013; Hogy et  al., 2013; Jarvis
et al., 2013; Fuchs et al., 2014; Goldner et al., 2015).
To date, all published studies are short term;
long‐term studies are needed to thoroughly
examine the impact of these deficiencies.
Much of what is known and applied in the
practice of V‐OP is gleaned from centuries of
work in the human field. Despite the paucity of
studies specifically related to V‐OP, by inte­
grating H‐OP experience with good science
already documenting the pathomechanics of
limb dysfunction and loss in the canine, there
seems to be adequate basis for pursuing V‐OP
even as we wait for science to catch up.

Applied biomechanics and

control systems

Equations and terminology

F = MA: force (F) is the product of mass (M) and

acceleration (A).

Mo = FD: moment (Mo*) is the product of force

and the perpendicular distance (D) from

ground reaction force vector to the pivot

point (joint).

Moment (Mo*): the tendency of a force to

rotate an object about an axis. This force can

arise outside the body (e.g., gravity, splint,

orthosis) or can be created by the body (e.g.,

muscles, tendons, ligaments, joint capsules)

(Figure 11.1).

Ground reaction force (GRF): the equal and

opposite force to the total body force (TBF)

exerted by the ground during any phase of

weight bearing.

Lever arm: the perpendicular distance from

the axis of rotation to the line of action of the

force (e.g., the pes is the distal lever arm for

the tarsus, while the manus is the distal lever

arm for the carpus).

Torque: a measure of the turning force on an

object.

Total body force (TBF): sum of the gravitational

(vertical) force and inertial (horizontal) forces

acting upon the body’s center of mass. The

TBF vector terminates through the middle

of the anatomic structure in contact with the

ground (e.g., the metacarpal or metatarsal pad

in stance). For practical purposes the thoracic

limb TBF vector originates in the mid‐pectoral

girdle, while the pelvic limb TBF vector orig­

inates at the sacroiliac joint. These locations

shift with movement.

Veterinary orthotic and prosthetic devices

create external moments for the body when the

body is unable to create an adequate internal

moment to resist forces acting upon a joint.

* Though moment is generally listed as “M”, we

have used Mo here to differentiate it from mass.