Angular and Rotational Deviations - General

I. General

1. Angular deviations (in the frontal plane) are defined as:

1. Valgus whereby the segment of the limb, immediately distal to the affected joint/growth plate, is deviated laterally.
2. Varus whereby the limb segment below the deviation is deviated medially.
3. Bear in mind that the same limb may present valgus and varus deviations at different points e.g. carpus valgus with fetlock varus.

2. Varus and valgus deviations can be observed by:

1. Viewing the limb from the front or the hind (often useful for evaluating fore limbs too).
2. Viewing the limbs from above, positioning oneself close to the shoulder or the hip of the foal.
3. On the fore limbs, and to judge cannon bone – Pastern alignment, by picking up the fore limb at the distal end of the cannon bone, whilst letting the digit hang down freely.
4. A long ruler or a farrier’s rasp can be useful as a visual guide, when in doubt.
5. Dorso-palmar/plantar x-rays permit accurate measurements, the assessment of ossification of carpal bones and the exact area where deviation takes place; the use of long cassettes is recommended. (Assessment of ossification of tarsal bones is best done with latero medial x-rays of the hock)
   Editor's Comment - Beware of assessing a fetlock as valgus, on an outwardly rotated fore limb. For there to be a valgus fetlock, the pastern Varus deviations tend to get worse with growth, when left untreated, valgus deviations tend to self correct with widening of the upper body.

3. Treatment of angular deviations depends on active growth plates and includes:

1. Trimming:

1. Correct hoof flares on the side of the hoof to which the lower limb deviates to.
2. Lower the hoof on the side the distal limb deviates to, only if this side is too high.
3. Trim the frog, which is comparatively larger in a foal than in an adult horse, asymmetrically – More on the side the limb deviates to.
4. Thin the hoof wall on the side of the deviation.
5. Ideally it is better to trim a little often, than a lot at long intervals.
6. With short hooves and/or larger deviations, there is a limit to what you can achieve with trimming.

2. Lateral or medial extensions to the hooves

1. With polymers like polyurethanes (e.g. superfast, adhere) or polymethylmetacrylates (PMMA) (Equilox, Bond n’Flex, TopGum etc.)
         i. Polyurethanes like Superfast are quick setting and wear resistant.
         ii. PMMAs have excellent adhesion, but should be reinforced with glass-carbon or Kevlar fibers, to increase their resistance to wear.
2. With foal shoes; respect foal shoe removal times, relative to the foal’s age (see guidelines in section).

3. Surgery

1. Periosteal stripping under general anesthesia on the "hollow" side, at the growth plate where the deviation takes place, that is, on the side which has an angle of less than 180°.
2. Transcutaneous growth plate stimulation with an 18G, 40mm needle. This can be done with local anesthesia, surgical prep of the overlaying skin and approximately 10 mm deep stabs into the growth plate, on the side where growth needs to be stimulated (concave side),moving the needle in a fan shaped pattern through the single cutaneous perforation into the underlying periostum [1]. Advantages of this technique relative to periosteal stripping are that it can be done at the farm, and it doesn’t cause as much periosteal reaction or scarring.
3. Transphyseal bridging with screws [2], screws and wire, screws and plates under general anesthesia.
4. Periosteal stripping, or transcutaneous stimulation of the growth plate, aims at increasing growth on the ipsilateral side, does not over-correct, is repeatable after a 6 week interval, and depends on an active growth phase of the treated physis.
5. Transphyseal bridging is a growth retardation procedure on the side with a larger angle than 180°, the implants have to be removed (2nd surgery) as they may over-correct and they still work at slower (later) phases of physeal growth [3].

4. Combination of surgery and hoof extensions

1. Periosteal stripping or transcutaneous growth plate stimulation work for 4 to 6 weeks and are synergetic with hoof extensions on the opposite side of the limb, e.g. lateral stripping of the distal physis of the radius and medial hoof extension for the correction of severe carpus valgus.

4. A rotational deviation (in the horizontal plane) is defined as an axial rotation of a limb segment relative to the segment proximal to it.

1. It can be inward or outward relative to e.g. inward rotation of the digit relative to the cannon bone.
2. Rotations can best be observed from above, looking downward along the limb.
3. Rotations of the digit, relative to the cannon bone, can be judged by picking up the limb loosely at the distal end of the cannon bone, and letting the digit hang.

1. Observe the direction of the frog, relative to a line perpendicular to the ground.
2. Rotate the hoof capsule gently, it will rotate more, and with greater ease, in the direction of the rotation of the digit.

5. Treatment of rotational deviations

1. Only rotations of the digit relative to the cannon bone can be corrected by trimming or hoof extensions.
2. Trimming or hoof extensions should extend the toequarter area of the hoof, opposite to the direction of the lower limbs rotation e.g., a lateral toe extension, to correct an inward rotation of the digit relative to the cannon bone.
3. Outward rotations of the entire fore limbs from the elbow down, present at birth and in the first weeks – months of life, tend to self-correct with growth and widening of the thorax, and should therefore not be treated with hoof modifications in the first 6 months.
4. Inward rotations tend to get worse with growth, and should be treated more aggressively than outward rotations, which have a tendency to self-correct.

II. Treatment of Specific Angular And Rotational Deformities

Lower limb growth plates, around the fetlock, close functionally a lot earlier than the distal plates of the tibia and radius; priority should therefore be given to get the lower limbs well aligned at the fetlock within the first 3-4 months of the foal’s life. (See Table I Chapter II).

1. Fetlock varus
   
   Figure 1.
   

1. Frequent condition in all breeds, including trotters, warmbloods, Andalusians and heavy breeds but also of the hinds of thoroughbreds.
2. Can be masked, upon superficial evaluation, by valgus carpus or hock, or by outside rotation of the entire limb.
3. Needs conscientious treatment within the first three months, because of lower growth plates closure times. Tends to worsen with growth.
4. Can be present at birth (check for latero medial laxity at the fetlock).
5. Often acquired during growth in heavy, wide breasted foals or as a consequence of weight bearing on the opposite limb to an injured limb.
6. Trim medially, save hoof laterally.
7. Extend with a polymer extension to the lateral side.

1. Ideally to the extent to where the outside of a hoof, belonging to a normal digit, would reach.
2. Extend the whole side wall, including the heels.
3. Beware of pinching or burning the coronary band at the heels with the fast setting and heat producing polymers.
4. Do not let it grow forward too much, as it will then become a lateral toe extension, favouring outward rotation of the digit. Trim regularly.

8. Extend with a lateral extension foal shoe.

1. With large degree of varus (>3-4°), present at birth, or acquired from overload on one limb, apply lateral extension cuff type foal shoes, as these can usually extend further than extensions out of pure polymer, they also "pull on" the whole hoof, not only the side wall.
2. Wide lateral extensions with foal shoes, which can have as much ground surface as the hoof itself, are also called for when the fetlock varus belongs to a limb which has an added varus at the carpus or hock.
   E.g. "Windswept" foals which are born with one hock varus and the opposite valgus, often have a varus fetlock on their varus hocked limb, both joints react well to a wide lateral extension, applied in the first days after birth.
3. When using cuff type shoes, set the cuff a bit wide on the side of the extension, as the hoof wall there tends to be a little straighter.
4. Respect foal shoe removal times (Table II, Chapter III).
5. Do not raise and then extend the lateral wall, only extend it.

9. Surgery

1. Stripping or transcutaneaous stimulation of the medial aspect of the distal growth plate of the cannon bone and/or the proximal G.P. of the first phalanx.
2. Take dorso palmar x-rays to decide, and as a baseline to judge improvement.
3. In the author’s experience, periostal stripping of these growth plates results in more periostal reaction and visible swelling than stripping of the higher growth plates.
4. To be done in the first three months of life.
5. Transphyseal bridging of the lateral aspect of the distal G.P. of the cannon bone, can be attempted for severe deviations (>4-5°), and when time is running out (10-14 weeks of age)

2. Fetlock valgus
   
   Figure 2.
   

1. True fetlock valgus is a rare condition.
2. Check by hanging the limb.
3. Tendency to self correct permits less aggressive treatment.
4. Check for latero medial laxity at the fetlock in the newborn.
5. Trim laterally, save medially.
6. Small medial extensions with polymers may be of help.

1. Do not have extension on the medial wall in the toe area, as this easily causes inward rotation of the digit.

7. Surgery is rarely called for

1. Lateral stripping or physeal stimulation of distal GP of MC/MT III and/or of proximal GP of PI.
2. Medial transphyseal bridging of distal GP of MC/MT III.

8. Do not over correct!

3. Inward rotation of the digit, relative to the cannon bone
   
   Figure 3.

1. Frequent condition, often acquired during (fast) growth.
2. Contributing factors may be:

1. Stocky heavy breeds or individuals.
2. Hilly paddocks.
3. DIP hypo extension (club foot): most club feet are also turned (rotated) inward.
4. Mistaken "correction" of outwardly rotated, base wide stance of entire limb.

3. Trim medial toe, sometimes reduce lateral heel flare, save or leave extra hoof at the lateral toe area.
4. When not enough hoof is available, extend lateral toe with polymers.
5. Keep monitoring the condition as it tends to grow worse with growth and increase in width/weight.

4. Outward rotation of the digit, relative to the cannon bone
   
   Figure 4.
   

1. Rare condition on the fore limbs, more frequent on hind limbs.
2. Check your diagnosis by hanging the limb, looking for the way the frog points and manipulating the hoof outwards and inwards.
3. Tendency to self correct, treat less aggressively.
4. Trim lateral toe, reduce flare on medial heel if present, save medial toe.
5. Extend medial toe slightly with a polymer if the hoof is worn too much in this area.
6. Monitor, do not over correct.

5. Carpus valgus
   
   Figure 5.
   

1. One of the most frequent conditions, usually present at birth.
2. Tendency to self-correct (Wolf’s law [4]) is dependent on:

1. Degree of angular deviation; up to 10°deviation causes faster growth on the concave side of the distal growth plate of the radius, larger degrees of valgus benefit from treatment, as excessive one sided pressure on the growth plate may actually retard growth there.
2. Age: the younger the more self-correction is possible; however distal growth plate of the radius is one of the latest physa to close functionally.

3. Other considerations:

1. Extra cellular articular cartilage matrix, undifferentiated at birth, differentiates in pressure and tension resistant areas in the joints at a fast rate in the first 6 months of life, slower thereafter. It is therefore useful to get correct alignment as soon as possible [5].
2. A slight degree (2-3°) of valgus at the carpus might be physiological, as it allows for perpendicular weight bearing of the lower limb, in the stance phase at speed.

4. Check for lateromedial laxity at the carpus at birth.

1. If present, and there are other reasons to suspect dysmaturity, x-ray for complete ossification of carpal bones.
2. If incompletely ossified, bandage and give stall rest.
3. Medial extensions for 1 week with a cuff type shoe, helps prevent lateral crushing of the carpal bones.

5. If at birth valgus at the carpus is larger than 10-12° with no laxity (x-ray, use visual guides like rulers):

1. Extend medially with a cuff type shoe for a week.
2. Foals can be turned out normally with these shoes.
3. A polymer extension afterwards, if still needed.

6. If valgus is between 5° and 10° at birth (with no laxity), extend medially with polymers or cuff type shoes.

1. Polymer extensions have the advantage that they do not have to be removed as quickly in the very young foal, as cuff type shoes.
2. Prevent the medial extension from growing too far forward as it will create inward rotation of the digit; trim extension at the medial toe and reapply at the medial heel.
3. Round off borders well to prevent striking injuries, although in the author’s practice these are almost unheard of.

7. Evaluate cannon bone – Digit alignment.

1. Do not apply medial extensions for correction of valgus carpus if the fetlock is varus!
2. Do not leave the medial side higher than the lateral side when extending medially; the extension will amplify the latero-medial height imbalance, twisting the digital joints and causing varus fetlock and inward rotation of the digit.

8. After 5-6 weeks of age medial extensions by themselves increase the likelihood of deviating and/or rotating the digit inwards.
9. At this age, and if there is the slightest hint of a medial deviation of the digit, it is advisable to combine medial extension with:

1. A lowering of the medial hoof wall.
2. Periostal stripping or transcutaneous physeal stimulation on the lateral side of the distal growth plate of the radius, as these will work in synergy, and reduce the risk of creating a varus fetlock.

10. Both medial extensions and lateral GP growth stimulation (distal radius) are repeatable in the case of severe (>15°) carpus valgus defects [6]
11. Severe (>15°) carpus valgus in 0-3 month olds, and large (10-15°) carpus valgus in foals 3-6 months old, may benefit from medial transphyseal bridging.
    Editor's Comment - An early approach, combining repeated medial extensions with lateral distal radius G.P. stimulation, can obtain satisfying results in up to 20° valgus at the carpus.

6. Carpus Varus
   
   Figure 6.
   

1. Rare condition.
2. May be present at birth, or acquired on the opposite limb to an injured one.
3. Keep in mind that 2-3° valgus is normal for the carpus; by this token, a straight radius – MC III alignment, could be considered as "varus".
4. Needs aggressive, early treatment, as the foal’s development tends to worsen the condition.
5. Start with a lateral extension at birth:

1. Cuff type shoe initial week
2. Followed by a polymer extension

6. If needed, medial stimulation of the distal GP of the radius.
7. There is less concern that lateral extension of the hoof will cause fetlock valgus, instead of straightening the carpus varus, as with the opposite correction (medial extension for carpus valgus creating fetlock varus).

7. "Offset" carpus
   
   Figure 7.
   

1. This condition is correctly described as a valgus radio carpal joint, in combination with a varus carpal – Metacarpal joint.
2. The combined angular deviations are characterized by:

1. An "oblique" carpus, as seen from the front, whereby the two rows of carpal bones are not parallel to the ground.
2. Distal radius ending on the medial aspect of the proximal carpal bones.
3. Proximal MC III originating below the lateral aspect of the distal carpal bones. (Radius and MC III are not in line)
4. A ruler applied to the medial side of the carpus will project downwards to the outside of the hoof, while this is neither the case in a true carpus valgus, or in a normal carpus; in the first case the line will fall to the inside of the hoof; with a normal carpus it will fall approximately to the middle of the hoof.

3. The condition was considered by the author to be congenital (and indeed is frequently present in the affected foal’s dam), a recent report, however seems to imply that it can also be acquired [7].
4. Objective, baseline, deviations can be established with dorso palmar x-rays of the carpus.
5. Offset carpii may cause the following problems in the (young) adult performer:

1. Medial splints, as the MC II (medial splint bone) is overloaded by the medially displaced distal radius, leading to entheseophyte formation at the proximal third of the interoseous ligament.
2. Over 5 times larger incidence of carpal lesions in racing Thoroughbreds than with normal, or slightly valgus carpal conformation.
3. Hang phase of the stride, is characterized by an initial lateral deviation of the hoof – lower limb from the sagittal plane, followed by a medial deviation before setting the hoof down. This "S" shape of the suspension arc of the limb, is readily seen in movement from the front, and heavily penalized in dressage competitions.

6. Correction of radio carpal valgus, in combination with carpo-metacarpal varus, can be attempted by:

1. Lateral growth stimulation (stripping or transcutaneous stimulation) of the distal physis of the radius, in combination with a lateral hoof extension.
2. Lateral growth stimulation of the distal physis of the radius, in combination with medial stimulation of the distal physis of the MC III [8].
3. A combination of a. and b.

7. In any case it is prudent to keep the lower limb from increasing it’s medial deviation (carpal-metacarpal varus) by:

1. Trimming; saving the lateral hoof while rounding off the medial side.
2. Lateral extensions with polymers.
   Editor's Comment - Do not confound carpus valgus with "offset knees", as the approach to the hoof is diametrically opposed; medial extension in the case of carpus valgus; lateral extension in the case of "offset" carpus.

8. Outward rotation of the entire front limb
   
   Figure 8.
   

1. Natural in lightly built breeds at birth ("A" frame stance).
2. Does not need correction in the first 6 months of life, as it tends to self correct with widening of the breast.
3. May erroneously lead to valgus fetlock diagnosis.
4. At a walk foals may set down their foot on the outside wall.
5. Hoof shape generally remains symmetrical.
6. (Gently) pushing a balled fist, between the elbow and the ribcage of the foal, will rotate the entire limb inwards to a more "normal" stance.
7. This exercise, together with adduction exercises of the forwardly stretched limb, are useful physiotherapy for this condition, perhaps better not started before 12 months (and therefore outside the scope of this chapter).

9. Windswept: Valgus + opposite varus hocks
   
   Figure 9.
   

1. Varus hocks are much more frequent than varus carpii, usually as part of a condition known as "windswept", whereby both hocks are deviated in the same direction, one valgus one varus.
2. The condition is attributed to intrauterine positioning; the author has variously tried to find correlations with gestation length, dam’s age, hind feet first presentation at birth etc., without significant results.
3. Windswept foals, not only have angular deviations of both hocks, their whole pelvis is usually tilted downwards on the side of the bowed (varus hocked) leg.
4. Newborns often have problems standing and ambulating on the varus hind, the hoof can quickly become severely distorted.
5. Valgus and varus hocks are treated similar to the carpii.
6. Distal tibial growth plates close slightly earlier than distal growth plates of the radia (functionally at ± 8 months).
7. Correction in the newborn consists of:

1. A large lateral extension on the hoof of the varus-hocked limb, with a glue-on cuff type foal shoe.
          i. Don’t glue the lateral side of the cuff on too tightly, as the lateral wall is often atrophied.
          ii. There is often also a degree of D.I.P. hyper-extension present (flexor flaccidity); if this is the case, extend the shoe both laterally and plantarly.
2. A usually smaller, medial extension on the hoof of the valgus hocked limb; the size of the medial extension depends on:
          i. The amount of valgus deviation of the hock, keeping in mind that in most light breeds, a 2-3° valgus of the hock, is more "normal" than straight (in the frontal plane) hocks.
          ii. That there is no varus fetlock on the same limb: hind limb fetlocks need even more precocious correction when varus than front limbs. In the case of varus fetlocks, align MT III and digit before correcting the valgus hock.

8. Lateral extensions on the varus limbs of windswept newborns with cuff type foal shoes:

1. Dramatically improve their stance and ambulation.
2. Can be followed, after a week and shoe removal, with a trim and a lateral hoof extension with a polymer.
3. Can be used again in the 3-4th week of life if necessary.

9. Be aggressive in treating any varus deviation (hock, fetlock) on a hind limb of a trotter, as this will lead to cross gaited interferences, when in training.
10. As is the case with the carpii, valgus hocks tend to self correct, varus tends to correct less spontaneously and needs more attention.
11. Valgus angular deviations of the hock respond to the usual surgical techniques:

1. Lateral periostal stripping, or transcutaneous physeal stimulation, at the site of the distal growth plate of the tibia.
2. Medial transphyseal bridging, which can also be done with a single lag screw.

12. Varus hocks can benefit from surgery at the distal growth plate of the tibia by:

1. Medial stripping or physeal stimulation.
2. Lateral transphyseal bridging.

13. Surgery for the valgus hock is recommended if:

1. There is no progress with hoof extensions in the first 4 weeks.
2. Hock after 4 weeks is still more than 10-12° valgus.
3. The fetlock of the same limb is varus (lateral tibia growth plate stripping + lateral hoof extension in this case!)

14. Surgery for the varus hock is recommended if:

1. There is no progress with hoof extensions in the first 4 weeks.
2. Hock after 4 weeks is still more than 6-8° varus.

15. Surgery is synergetic with hoof extensions which should be applied regardless.