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August 2005

The Pelvic Fulcrum

There is a tendency to underestimate the significance of pelvic attachments in equine locomotion.  While everyone knows that power comes from behind, the incidence of muscular and other soft tissue injuries in the area of the upper pelvis suggests that, in all probability, all powerful forward impulsion is hinged from the pelvic attachments.  Furthermore, the preponderance of near-side injuries, suggests the left hind limb is the lead limb for most horses.  It is accepted there could be other contributing factors in this.

Equine muscular injuries are very similar in cause and effect to human muscular injuries.  Virtually all athletic horses succumb to the demands of exercise in a similar way to that in which human athletes do. 

The most common injury is a physical disruption of individual muscle fibres, rather like that recognised with tendon fibres, followed by the consequential repair processes accepted in medical pathology.  Crudely, a tear leads to a hole in the muscle body.  This fills with blood and the repair involves formation of scar tissue.

Untreated, the dynamics of muscle function are altered.  Pain, as any athlete will attest to, forces an alteration of movement.  For the human athlete, this usually prevents training or any kind of competitive activity.  For a four-legged animal, the effect is to alter the gait in order to exclude or reduce use of the injured part.  Stride length, or pattern, may be changed and the flight of the limb then leads to a different type of contact with the ground.  The impact may occur, short, long, wide or inside the natural position.

The consequences of the latter may alter concussive influences, and may lead to injury of remote structures from the original injury.  However, there are other complex influences of injury to a single muscle that can have a spiralling effect and gradually lead to injury of other limbs without further external trauma.

Among these are the increased loading that occurs on the off hind limb, for example, when, the near hind has been injured.  There is also a tendency to implicate the diagonal forelimb.  Whatever the precise reason for this, it forms a pattern in complex muscular injury and, for effective treatment of the problem, has to be addressed if the animal is to return to athletic soundness.

Diagnosis

Looking at the rear-end profile of the grey horse above, it is easy to recognise a lack of uniformity between the two sides of the pelvis.  This may be explained by the fact the horse is standing on a slope, thus necessitating an uneven use of quarter muscles to maintain its stance. 

On the other hand, such an obvious difference can easily be a result of soft-tissue injuries in the pelvic region.  The first step towards diagnosis is to study the horse from behind standing evenly on a level surface.  It is often possible to feel injuries in the quarter muscles by hand; it is always possible to identify them specifically with a faradic-type current that stimulates movement and defines the limit of injured areas.

It is also important to gauge the animal's action at the walk and trot.  An affected limb takes longer to engage and the arc of its flight is different from a normal limb.

A pelvic muscle injury may be extensive, and may be accompanied by wasting or hypertrophy (swelling) of the same or adjacent areas.  While many such injuries are a response to a single acute trauma, like slipping-up, there is a likelihood that some begin as very small areas that expand by repeated aggravation.  This is a scenario recognised in human athletics, where muscular pain is caused by micro-injuries that resolve with rest and massage, but may lead to greater complications if ignored.

Looking at the same horse below, the most critical anatomical point is the outer angle of the ileum, towards the left upper corner of the picture, where the main anchor of forward impulsion would appear to be located.  This is close to the area of union between the sacrum, or pelvic roof, and the ileum; commonly seen as a point of lameness.

While flexion and extension of the hocks may well be critical to propulsion, there is good reason to suggest that the power comes from the pelvic attachments.  This is due to the contraction of muscle attached to bones which are (fairly) fixed, aided by the various ligaments, etc, that are critical to the whole process of movement.  Not to forget structures moved by the same muscles when they contract, like hip, stifle and hock, also their related bones.

It is easy to see that reluctance to use an area of muscle like this is going to have a complex influence on such structures (and even more remote areas) and the way they move

Treatment

History teaches us that the effective treatment of muscular injuries involves massage.  Human therapists have effectively treated athletic injuries for decades (perhaps centuries) with little else.  The problem with equine quarter injuries is the extent of the lesions and depth of the tissues; and it is important to identify the full extent of an injury for it to be effectively treated.  It is also vital to find the effects on muscles of other limbs and reverse the processes involved.

Treatment involves stimulation of the injured muscle with electrical current, also the breakdown of adhesions, etc, with something in the nature of therapeutic ultrasound or laser therapy.

The problem with some modern systems is their failure to penetrate deep into the injured tissues of horses, a consequence of which may be short-term relief followed by recurrent lameness.  The aim of any therapist has to be the restoration of full movement in an injured area as well as normal surface anatomy combined with full and normal action of the affected limb, or limbs.

As many of these injuries have a chronic development, the treatment period is likely to take weeks rather than days.  In many cases, a sudden onset of lameness is associated with a more slowly developing cause, all of which has got to be reversed before the horse can be returned sound to work.

Peter Gray

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