20/10/2026
DOES RAISING HEELS INCREASE SUSPENSORY LIGAMENT STRAIN?
Or are we so focused on the results of misinterpretation of isolated experiments that we are overlooking the biomechanics of the entire digit or indeed, horse!?
Throughout my clinics across the USA, suspensory ligament injury prevention and rehabilitation has been a recurring topic.
And something has become increasingly apparent to me.
There is a fundamental misunderstanding of the mechanical influences affecting the suspensory apparatus, particularly when it comes to hoof morphology, phalangeal alignment, ground reaction forces and compensatory posture.
I have repeatedly spoken to farriers who have been presented with horses suffering from suspensory pathology, alongside significantly compromised hoof morphology, collapsed heels, low or negative palmar/plantar angles and broken-back phalangeal alignment.
Yet the veterinary instruction has been to avoid raising the heels because research suggests heel elevation increases suspensory ligament strain.
Instead, they are instructed to apply a particular “suspensory shoe”, sometimes while actually encouraging the underlying mechanical dysfunction.
But that shows a misunderstanding of the effect of raising heels versus the effect of restoring compromised phalangeal alignment and net result in suspensory strain!
FIRST, LET’S UNDERSTAND THE PHYSICS.
One of the primary functions of the suspensory apparatus is to resist fetlock extension during weight bearing.
As the ground reaction force (GRF) acts upon the limb, it creates external moments around the joints.
The magnitude of these moments is determined by the force and the perpendicular distance between its line of action and the relevant centre of rotation.
Moment = Force × Moment arm.
The greater the external extension moment acting around the fetlock, the greater the mechanical demand upon the structures responsible for resisting it, including the suspensory apparatus.
SO, WHAT HAPPENS WHEN THE HOOF BECOMES MECHANICALLY COMPROMISED?
A horse with significant caudal hoof collapse, a long toe, negative plantar angles and broken-back phalangeal alignment has altered spatial relationship between the hoof, the ground and the joints above.
These changes move the CoP away from the centres of rotation! Increasing the mechanical demand on the Suspensory!!
The horse is not a collection of isolated joints. It is an interconnected mechanical system!
When the hoof-ground interface becomes mechanically compromised, the horse may reorganise its posture to maintain equilibrium.
In the hindlimb, this can manifest as a camped-under posture.
This also changes the spatial relationship between the fetlock centre of rotation and the GRF line of action, with the added increase of rotational demand on the suspensory from the lever arm created from the transference of the horse’s weight way behind the bone column!
And the suspensory apparatus must contribute to resisting that increased moment that is create from both directions as a result of long toe low heel!
The mechanical demands created by the entire limb’s orientation relative to the ground reaction force plus the mechanical demand created by the forward migration of the PoF application create an exponentially larger increase in suspensory strain than the isolated increase in suspensory strain from regaining spatial balance of the digit!!
The point is that an experiment measuring changes in suspensory strain following heel elevation under controlled, cadaver limb conditions does not necessarily tell us what happens when we restore severely compromised phalangeal alignment in a live horse that has developed abnormal compensatory posture.
Also! There is a fundamental difference between raising the heels of an already functional hoof and raising the heels as part of correcting a mechanically compromised hoof.
In the first situation, we are introducing a mechanical change to an existing functional system.
In the second, we may be removing a mechanical disadvantage that has been influencing the loading environment of the entire limb.
A small increase in suspensory strain measured under one experimental condition does not mean that an intervention increases overall suspensory loading in a horse with compromised hoof morphology and/or posture.
Because the intervention will have a much greater influence on the mechanical demands placed upon the suspensory apparatus than the isolated effect of heel elevation.
If an intervention reduces the perpendicular distance between the GRF line of action and the fetlock centre of rotation, we reduce the external extension moment acting around that joint. That reduces the suspensory demand exponentially more than the isolated increase!
Plus, the reduction in suspensory demand resulting from improved posture is considerably greater than the small increase in strain reported following heel elevation under isolated experimental conditions
So when added together in the case of restoring spatial balance in NPLA, the isolated increase in suspensory strain becomes completely and utterly insignificant!
But unfortunately, when not considering the bigger picture, small experimentally measured effects of heel elevation are assumed to outweigh the potentially much larger effects of digit balance and postural correction.
AND THEN WE HAVE THE SURFACE TO CONSIDER!
In my previous article on suspensory injury, I discussed the conflict between suspensory loading on firm and deformable surfaces.
On firm surfaces, the external fetlock extension moment and the degree of fetlock descent are important considerations.
Increasing caudal support may help manage fetlock extension under these conditions.
However, on deformable surfaces, toe pe*******on can introduce another mechanism of suspensory loading.
As the toe sinks into the surface, the resulting change in hoof orientation and loading can increase the mechanical demands placed upon the suspensory apparatus.
Consequently, an intervention that is beneficial on one surface may become counterproductive on another.
A wider toe may help limit pe*******on on deformable surfaces, while increased caudal support may be more advantageous on firm ground.
And these considerations become even more complicated when the horse presents with poor phalangeal alignment and compensatory posture.
We now have several interacting mechanical variables
• Hoof morphology and structural integrity.
• Phalangeal alignment.
• Centre of pressure and GRF line of action.
• Limb posture and external joint moments.
• Surface-dependent hoof-ground interaction.
• The mechanical effects of the shoeing intervention itself.
How can we possibly prescribe a shoe based upon one of these variables while ignoring the others?
SO, SHOULD WE RAISE THE HEELS OF HORSES WITH SUSPENSORY INJURIES?
Sometimes yes. Sometimes no!
And that is precisely the point.
We should not categorically raise heels, and equally, we should not categorically refuse to raise them because an experimental study reported increased suspensory strain.
We need to understand the mechanical condition of the individual horse.
We have to start All considerations by recognition of what is ideal for that horse!
If the caudal hoof has collapsed, we must address that structural compromise!
The aim is to restore a mechanically favourable and structurally functional hoof first. Then manipulate GRF’s from there.
This brings us onto THE PROBLEM WITH PATHOLOGY-SPECIFIC SHOEING.
I worry that we have developed an approach where the diagnosis dictates the shoe.
Suspensory injury? Apply a suspensory shoe.
Deep digital flexor injury? A bar shoe or onion heel
The hoof architect did a great post about this recently.
The purpose of farriery is not simply to match a shoe to a pathology!!
It is to understand the forces acting upon the limb, the mechanical demands placed upon the tissues and how we can manipulate the spatial balance of the digit and hoof-ground interface to create a more favourable functional environment.
Because if poor phalangeal alignment contributes to abnormal posture, and that alignment and posture increases the external moment acting around the fetlock, then refusing to address the alignment may mean preserving the very mechanical disadvantage contributing to the pathology, while prescribing a suspensory shoe!! The insanity!
The goal is to reduce the pathological mechanical demands placed upon the injured structure while restoring the functional integrity of the entire limb.
And that requires us to understand the physics, not simply memorise the prescriptions.
Previous discussion on hindlimb suspensory loading and posture:
https://www.facebook.com/share/p/1CfQhRGwMa/
My article on surface-dependent suspensory mechanics:
https://www.theequinedocumentalist.com/suspensory-ligament-injury-surface-dependent-mechanics-pob-conflict-and-farriery-strategy/
