Responses: Excessive IR with AFO

Responses: Excessive IR with AFO

Gina Retallack

12/29/2011

Here are the responses to my question:
I'm currently treating a 4 y/o boy with CP (hemi) who presents with left equino-varus (correctable) and IR (femoral anteversion). Before he came to me, he was using a custom PLS- AFO with dynamic trim at the foot (SMO-style). I would think this would be the best orthotic treatment for him also (PLS AFO or SMO with kiddie gait...along these lines), but the parents told me that this AFO made his gait worse because it exacerbated his IR (with increased circumventing during swing resulting in frequent tripping), so they stopped having him wear it after a couple of months. As a result, they want nothing to do with this orthosis. We tried having him wear just an SMO (DAFO #4) with a proximal wrap-around strap, which helped control the triplanar deformities in his ankle/foot, but obviously didn't help control the equinus (although it didn't trigger the excessive IR). Can someone shed some light on why his IR would worsen while wearing the AFO?

Thank you everyone for your prompt responses.

It has been my experience that IR increases with AFO because anything that blocks plantar flexion, or resists it, allows the abnormal hip forces, (rotators, tight medial hamstrings) to fire and show up more in gait. The faster the foot can get to the ground the less you will see it. I have also seen it with SMO's on on patients that pronate. Pronation can mask the internal rotation force. Once the SMO is on and the pronation is blocked then the foot has no choice but to internally rotate.
 The moral of the story is that anything that lets the foot plantar flex rapidly, will be better but the problem is always there it just isn't always visible.
 Hope this helps,
 Good Luck,
 Rob Biaggi C.P.O.

Did you see the patient wearing the brace? Did the leg internally rotate at heel strike as it pivoted on the heel? Did they consider twister cables to address the IR? Sometimes if the foot plants slightly IR as the knee and hip progress over the IR foot an internal rotation torque is produced as the pelvis rotates around the planted foot which exacerbates the situation.

Sometimes medial external heel posting can be used to promote a slight external rotation so that the foot plants with slightly less IR and then the pelvic rotation does not exacerbate the issue. Twister cables are your answer.


If he has an equino varus deformity problem your correction of a neutral anatomical position of his foot and ankle will probably be lost if he has a tone response upon weight bearing on his left side. A flexible PLS is not strong enough to hold your correction.. A rigid design is more appropriate to hold your correction. There are many designs to choose from, and the decision is your own. In regards to his femoral inversion that is an anatomical problem and not correctable with your AFO. You may try a derotation strap from Cascade DAFO, any pediatric fabrication laboratory, or your own laboratory talent. It was not uncommon before plastics to use a Becker Orthopedic derotation cable attached to a metal AFO to control the IRD problems. Consult first with the patients physical therapist. If they approve then get the MD's approval; then ask the family. If everyone says yes get a new Rx. for billing.
rick/cpo

Hi Gina

Any proximal medial rotation (dynamic at the hip, femoral anteversion or tibial torsion) will usually result in lateral rotation of the foot on the tibia or forefoot abduction, also usually associated midfoot dorsiflexion and rearfoot eversion. The foot appears relatively normal during gait, but the tibia is rotated medially. The SMO used with Kiddie Gait reduces the deformity at the ankle and subtalar joints by re-aligning the foot to the tibial. That is a very appropriate goal for orthotic intervention. The problem is that this creates more of a toe-in posture during gait. I'm not sure, short of strapping, how to manage femoral anteversion. Is it confirmed that the femur is actually twisted or could it be coming dynamically from the hip. I don't know of any orthotic device that will address and correct femoral anteversion.

My two cents...

Bob



I sometimes see this when a patient is trying to shift his body weight over his foot and there is tightening of the muscles that prevent this dorsiflexion progression. Often people will try to shorten the lever arm that the foot creates by internal rotation or external rotation of the hip/ankle. Instead of using a PLS flexible design or just a SMO, I would be interested in what a solid or articulating AFO would do to his pattern. Try and add extra dorsiflexion if patient able to handle it. Adding a lateral wedge to his shoe may also help.



I am not sure but I'd say that if he has spastic CP that the heel cord is tight, along with the hamstrings and the hip adductors. By putting him into dorsiflexion from the PLS AFO and correcting the equinus it might be causing some imbalance that causes other muscles, say the hip adductors, to tighten up more and exacerbate the femoral anteversion. I've heard this can happen in spastic CP. By the same token if the achilles is tight and being stretched in an AFO it may be affecting how well he can flex his knee to swing the leg through. Thus knee hyperextension and circumduction. You'd have to watch his knee flexion with and without the brace to see if that is the case. It could also be he needs to relearn balancing and walking with the AFO. You could always try an AFO with an ankle joint and adjustable stop so you could allow some equinus in the beginning and then dorsiflex the foot as the child progresses. You can pair it with an SMO and the good thing about that is the child can use the SMO for walking short distances. Then the parents can use the SMO plus the AFOs for stretching or for long distances. Is the child getting PT? At the least I'd get the parents to put the child in an AFO/SMO for stretching at home, otherwise the equinus could become permanent.
  I've seen hip derotation straps for the anteversion. Surestep makes one. They might provide some gait training for the child. I've used them a couple of times but do not have a lot of information on either the effectiveness or the typical compliance of the patients. I get the feeling that in general the straps were used in therapy and that is all. But it might be worth trying if the parents can learn how to wrap them because it may help to show the child the proper way to turn his leg to walk. -Paula Martinek, LPO Port Saint Lucie Fl



Depending on this patient's tone (C.P.) The PLS AFO will allow ankle motion which will set off the extensor tone thus causing planter flexion and internal rotational pattern. (Primitive Pattern) Try a solid ankle AFO at first then over a period of several months, slowly allow some dorsal-flexion motion. (Very Little). This should improve his gait pattern.


Obviously not seeing this particular case the following may or may not be apropos. In the presence of anteversion or femoral torsion it is very common that an uncorrected foot will clinically mask the rotation. The the uncorrected foot allows the midtarsal joints to drop, obligating forefoot abduction. The same midtarsal collapse opens the calcaneal navicular joint which in turns removes the support of the talus, which then adducts and plantar flexes. The calcaneus mean while tends toward valgus. This foot position and in particular the midtarsal collapses removes the integrity of the forefoot lever arm from the hindfoot. Gradually, the calcaneus tends to plantarflex since its connection to the forefoot is poor, this in turns allows the gastrocnemius to shorten and not provide adequate function. Back to the torsion issue. As you are very well aware the talus adduction obligates the tibia to internal rotate more, the femur is obligated to follow which pulls the trochanter which place the gluteus maximus on an even greater stretch reducing its ability to fire with enough power to externally rotate the entire limb - so the whole cycle reinforces itself in a deleterious motor pattern reinforced with every step.

When you correct the forefoot and disallow the forefoot the abduction mask is removed and your have revealed the true internal rotation. In addition, if the heel makes good initial contact and the shoe heel is round and firm the IR moment is greater. A soft heel may ameliorate this but the child really needs a great deal of time to correct the motor pattern, usually a good PT will observe this and work on it. This will not resolve shortly, it is a matter of long term, multiple steps of learning an improved motor pattern. It may seem daunting but the alternative for the child is more plantarflexion, knee flexion, valgus and rotation, etc up the chain including lumbar lordosis.

It is frustrating but often the case that if the device is not revealing the IR, it is also not providing the foot correction.

Sometimes one can communicate the parents by demonstrating on them as they forcefully collapse the midtarsal joint, sometimes not. As my first sentence indicates this may not be true for your present case.

Good Luck,
 Don McGovern, CPO, FAAOP


because it's solid ankle and creates pivot point at heel strike? There's good reason for that foot to go down then.

there used to be a cute system of elastic straps that ER-d lower extremity. I forgot the name of it for good though.