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canine-biomechanics

Form-function changes (part 1)

The dog is more than ever the constant companion of human beings. Due to the large activity of the dog, orthopaedic disorders/diseases are also a major topic in veterinary practice. Due to the enormous range of possible activities for the dog, the orthopaedic disorders/diseases become more varied and partly more complex! Despite many diagnostic aids, the limp remains often unclear and without diagnosis! With this in mind, it is imperative that orthopaedics endeavor to take this into account when considering dog medicine. In 2007, I presented the concept of the form-function changes. In this article I would like to recall the concept as a topic with priority and to present a few cases.

 

Definition and task of orthopaedics

Orthopaedics includes the detection, treatment, prevention and rehabilitation of congenital and acquired deformations, malfunctions and diseases, besides injuries to the supporting and the musculoskeletal systems! This principle applies not only to a human being, but to a dog too. However, it is a fact that this principle has never been communicated in veterinary medicine in this way so far.

 

 

 

Definition form-function changes

Depending on the breed, the skeleton of the dog has a different shape. As an example, a Greyhound has a slim and strong deep chest which, in turn, allows it to hunt and chase a hare with a very fast speed indeed!

 

 

 

 

A Rottweiler, however, has a sturdy and muscular body in order to accomplish the task of security and protection services confidently. This reflects the high "shape variability" of the dog.  Thus, an optimal skeleton shape forms the basis for the desired task and full performance thereof.  From a Rottweiler, for example, no racing performance can be expected, in contrast to a Greyhound. Therefore, the shape of the skeleton of the breed is responsible for the performance. Only an optimal shape of the skeleton will provide full power and achievement! Provided we have achieved the basic requirement of a healthy skeleton (i.e. a healthy form), this skeleton is able to successfully fulfil the requested task. E.g. a Guard dog for security and protection services, or the Greyhound for racing or hunting purposes.  A healthy form meets full function! The skeletal system consists of supporting and moving organs. Both are inseparable.  Static and dynamic tasks complement one another, thus allowing a determined and purposeful movement.

 

 

 

In principle, the unity of form and function is only guaranteed if the structures involved in the musculoskeletal system in macro- and micromorphological areas are undisturbed in their integrity. The composition of these structures is partly genetically determined, but is influenced from outside too. At this point, I would like to draw attention to the elbowdysplasia.  This can be clearly put in the context of genetics but the biomechanics and the form-function changes must also be considered.  This can be modified through metabolic processes and numerous internal and external influences which can play a major role for the emergence of orthopaedic diseases, but also be the objective for therapeutic measures. Here, among other things, reference is made to kidney diseases or to tumors. The diagnosis of orthopaedic diseases cannot refer solely to analysis of form dysfunction but must also take these interactions into account which are significant for the overview of orthopaedic diseases.  Thus, the orthopaedist is challenged, in general, to keep the internal medicine or endocrinology (hormones) in mind, in addition to the primary moving structures and its diseases. As a special example please note the thyroid.  A longer-lasting orthopaedic disease, or a chronic pain process results in an underactive thyroid in the long-term. It goes without saying that the substitution of the thyroid (thyroid hormone therapy) does not solve the problem, but is merely a symptomatic therapy.  Unfortunately, this fact is repeatedly forgotten so that the hormonal system causes reactions to primary underlying diseases.  In this particular case, painful, orthopaedic diseases.

 

After these introductory remarks concerning orthopaedics and understanding with regard to the approach to orthopaedics, we now devote our attention to two practical examples.

 

 

Example 1

The dog shown in the first video was introduced and presented to me on the strength of a flashy gait and drift. The dog shows an oblique hind leg axis. Both hindquarters are shifted diagonally to the right, the one bone on the right  is "broken" and the mobility in the right thigh is totally reduced. Both front legs are kept very wide in the elbow region and turned outwards. The gait looks similar to a run by  "John Wayne”! The head position is rather low.

 

 

 

The second sequence of this specific case reveals that the dog achieved better directional stability and a better frequency of the movement pattern. Moreover, the head posture is upright, the elbow position now even and the axis in the sitting position practically on an even and regular level.

 

 

 

 

 

 

Taking the XR images into account, it is surprising to notice how smoothly the dog is still able to walk, in spite of these changes in the pelvis.  The scoop of ilium, as well as the sciatic notch with acetabulum, is rotating inward and the mobility of the thigh severely limited.  Basically, the dog is a silent sufferer! Due to the movement pattern of the dog it is clear that he is able to compensate a restriction for a very long time.  Long-term consequences of this form-function-changes can, however, lead to the development of osteoarthritis. 

 

 

Example 2

The reason for our second example is to judge gait.  The movement patterns of the hindquarters is tight, we see both hind legs practically through the forelegs. The right hind leg rotates outwards and the footprint is from inside to outside. The seating position is striking. The weight is shifted to the left and the right leg is significantly outside forward and set. The left thoracic limb turns compensatory outward.  During the physical examination, the right kneecap jumps right out when a little more pressure is applied (habitual dislocation of the patella).

 

 

 

 

The X ray photographs, in turn, have an impressive form-function change.  The thigh on the right side shows a bend, the kneecap moved inward.  On the lateral view you will notice that this bend is quite impressive.  Under these circumstances, this gait pattern is not surprising. Once the dog has completed its longitudinal growth, it is very useful to evaluate the skeleton again and subsequently it is advisable to arrange a corrective osteotomy, or then also the "Patella surgery". The aim of surgical intervention should be to correct the long-term optics of the movement pattern to the extent that the likelihood of osteoarthritis is reduced to its minimum for middle-aged and elderly dogs!

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orthoVET

Dr. med. vet.

Patrick Blättler Monnier

Fasanenstrasse 13

4402 Frenkendorf

Tel. 061 903 11 11

Fax 061 903 11 13

info@orthovet.ch

www.orthovet.ch

 

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orthoVET

Dr. med. vet.

Patrick Blättler Monnier

Fasanenstrasse 13

4402 Frenkendorf

Tel. 061 903 11 11

Fax 061 903 11 13

info@orthovet.ch

 

 

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orthoVET

Fasanenstrasse 13

4402 Frenkendorf

 

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