Orthotic Treatment for Morton’s Neuroma
Doug Richie, DPM, FACFAS, FAAPSM, Bruce Williams, DPM, and James
Jane Andersen, DPM, Gene Mirkin, DPM, and
Bruce Williams, DPM, James Clough, DPM, FACFAS
Flexible Hammertoes
Dr. Mirkin says orthotics can sometimes stabilize flexible hammertoes due to flexor stabilization and prevention of excessive pronation. By preventing the collapse of the medial longitudinal arch and keeping the subtalar joint from pronating beyond perpendicular to the weightbearing surface, he says the pull of the flexor tendons can decrease. Dr. Mirkin uses a 10-12 mm deep heel cup and will sometimes use extrinsic forefoot posting if a forefoot varus deformity is responsible for hammertoes caused by excessive pronation. He always warns the patient that the toes will still look contracted but they may not rub the shoes as much and therefore will feel better.
For flexible hammertoe deformities, Dr. Andersen usually prescribes a rigid or semi-rigid device with a rearfoot post posted to 4/4 motion. If patients are having any forefoot symptoms, especially metatarsal pain, she will use a metatarsal pad.
Hammertoes, notes Dr. Williams, are tough to treat with orthotics. As he says, some people will benefit from the use of sulcus raises or pads that allow the toes to grip properly. Some patients can benefit from a digital skive or pad to raise the toes above the level of the metatarsophalangeal joints by 3 to 6 mm, according to Dr. Williams. Ultimately, he notes any increase in a foot platform from a full-length orthotic or a digital skive can irritate a fixed hammertoe deformity.
“Treat these with caution but keep in mind you can use digital padding at certain toes and not on others to maximize the potential of the orthotic modification,” advises Dr. Williams.
When Dr. Horsley decides to use an orthosis for flexible hammertoe deformities, he tests the flexibility of the digits by loading the forefoot. If the digits become rectus during loading of the forefoot and do not remain plantarflexed through the maneuver, he will include a metatarsal pad on the orthoses in order to achieve rectus digits during stance.
If the digits are flexible and continue to plantarflex during the maneuver, Dr. Horsley incorporates a toe crest into the extension of the orthotic device. Dr. Clough believes orthotics can help with flexible hammertoe deformities. He says this condition is all about first ray insufficiency. If the first metatarsal does not bear enough weight, Dr. Clough notes that pressure transfers to the lesser metatarsals, causing swelling of the MPJs.
The small intrinsic muscles, primarily the dorsal and plantar interossei and the lumbricals, are dysfunctional as they pull on a swollen joint, according to Dr. Clough. In addition, he says if the windlass mechanism is not working, the plantar fascial slips inserting into the toes are not functional and wind up destabilizing the toe. A hammertoe is the result. When one can reverse these factors, Dr. Clough commonly sees the flexible hammertoes relax as normal stability improves and eventually the hammertoes straighten to a degree that they are often asymptomatic. He advises that corrections to the orthotic involve casting with the first, fourth and fifth metatarsals plantarflexed, and cites the use of the P4 Wedge.
When using orthotics to reduce flexible hammertoe contractures in cavus feet, Dr. Richie says the key is conforming the device as close as possible to the arch of the foot. Both he and Dr. Clough support the use of minimal arch fill. Dr. Richie advises against using rearfoot posting or plaster fill across the balance platform. He suggests adding a metatarsal pad to ensure support of the distal transverse metatarsal arch. Although he will observe lesions from hammertoes reduce in these types of patients, he will not see the deformity reverse.
Dr. Williams finds that patients tend to flex the digits due to an inability to get proper stable pressure/force under the first MPJ in most instances. However, he cautions that using the usual modifications on orthoses does not mean that the flexible hammertoes will go away. He usually uses a digital wedge (usually 3 to 5 mm thick, similar to a Cluffy wedge) across all the digits to assist with this.
Dr. Williams adds that dorsiflexing the digits can help decrease the need to flex, especially if a cutout allows the first metatarsal head to plantarflex. Equalizing the pressure and forces under all the metatarsal heads will often decrease the need for the lesser digits to flex at the proximal interphalangeal joint and distal interphalangeal joint, according to Dr. Williams.
Achilles Tendonitis
Dr. Williams says the most current literature on biomechanics of the ankle joint suggests that a lack of dorsiflexion range of motion is the most likely culprit leading to Achilles tendinopathy.He feels that when the ankle joint stops dorsiflexion too early in midstance, the Achilles will not get to full extension during eccentric loading. As Dr. Williams explains, this stops any energy potential building up in the Achilles that would then assist late midstance and propulsive concentric contraction. “This makes the Achilles insertion and tendon body work harder, and can lead to calcification and exostosis at the tendon insertion and trauma to the tendon itself,” says Dr. Williams.
All three panelists cite the use of heel lifts for the Achilles. More often than not, Dr. Mirkin finds that a heel lift does as much for Achilles tendinosis as a custom-molded orthotic. If rearfoot varus exists, he does not prescribe orthotics. For Achilles tendinosis, Dr. Andersen uses a rigid or semi-rigid device with a rearfoot post posted to 4/4 motion. She often adds a slight heel lift, especially if the patient responds to this clinically prior to orthotic scanning.
In cases with flexible rearfoot valgus, Dr. Mirkin most often uses a deep heel cup with 1/8 to ¼-inch of heel lift and posting to bring the rearfoot to perpendicular. If the hindfoot deformity is rigid, Dr. Mirkin has found that orthotics are not of much benefit. “In those patients, the heel lift rules in both result and cost savings to the patient,” he emphasizes.
When it comes to treating Achilles tendinosis, Dr. Williams says his goal is to get the ankle moving again via manipulation and the use of orthotics. He often uses a heel lift from 3 to 6 mm to accommodate the lack of motion at the ankle joint via dorsiflexion. If the patient cannot dorsiflex enough, Dr. Williams says he will “cheat” and lift the affected side to “fool the body” into thinking it did what it needed to do. Dr. Williams advises caution so one does not overload a long limb that way but says bilateral lifts will often keep that from happening and allow for proper function. He also emphasizes use of the ankle joint lunge test to measure flexed knee range of motion, saying it is the only test that is repeatable.
“When you start measuring this regularly, you will understand how many patients really have significant tightness in their soles and need to have heel lifts combined with orthotics to treat this effectively,” explains Dr. Williams.
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