A Guide To Orthotic Treatment For Metatarsalgia

Author(s): 
Jamie Yakel, DPM

   Pressure mapping is one method of evaluating pressure on the metatarsal head region and it can also be beneficial in evaluating pre- and post-orthotic efficacy. In addition, one can raise the metatarsal heads by using a metatarsal bar. Alternately, the clinician can leave the anterior edge of the orthotic full thickness as opposed to thinning it out at the distal edge. This will help transfer weight proximally and serves in a sense as an internal metatarsal bar.

A Closer Look At Conditions Related To Metatarsalgia

Intractable plantar keratoses (see “Key Insights On Intractable Plantar Keratoses” at http://www.podiatrytoday.com/key-insights-intractable-plantar-keratoses ) and calluses are painful conditions that can respond to orthotic modifications. Intractable plantar keratoses can be a result of a plantarflexed metatarsal, whether they are due to retrograde pressure of digital contractures or a structural abnormality. Finding the happy medium in regard to offloading the intractable plantar keratoses can be difficult. Metatarsal pads, metatarsal bars, dancer’s pads and padding are some of the modifications available. Again, a metatarsal bar can also transfer the weight proximally. A full-length topcover using Korex to accommodate the lesion(s) works very well.

   Another cause of metatarsalgia is early heel-off, which increases the pressure on the metatarsal heads and subsequently causes a longer duration of weightbearing. Evaluate for early heel-off, whether it is from a leg length discrepancy or equinus. Carefully assess the ankle joint for equinus. Dananberg’s manipulation method is an excellent adjunct one can perform to restore ankle joint range of motion.5 In combination with orthotics, this is an excellent way of reducing some of the metatarsal pressure.

   Morton’s neuroma is one of the most common causes of metatarsalgia. The diagnosis of Morton’s neuroma is clinical. The most common complaints are pain, numbness and tingling in the involved digits. Often, patients complain of a feeling of stepping on a stone or the sensation of a wadded up sock. Conservative treatment options consist of shoes with wide toe boxes; orthotics with a metatarsal pad or bar; steroid injections; non-steroidal anti-inflammatory (NSAID) medications; and alcohol sclerosing injections.

Can Metatarsal Pads Be Effective?

The addition of metatarsal pads is the mainstay in treating neuromas with orthotics. The purpose of metatarsal pads is to transfer the weight proximally to the metatarsal shafts but, in the case of neuromas, the purpose is to separate the metatarsal heads. Koenraadt and colleagues found the use of metatarsal pads increased the width of the forefoot, supporting the use of metatarsal pads in the treatment of neuromas.6

   Metatarsal pads come in various sizes and shapes. It is universally accepted that one should not place the metatarsal pad under the metatarsal head but proximal to the metatarsal heads. The width of the pad should support the second, third and fourth metatarsal heads, and avoid the first and fifth metatarsal heads. Be careful to avoid extending the pad proximally to the tarsometatarsal joints.

   The key component is where to place the metatarsal pad. Do you place it at the leading edge of the orthotic plate or have it extend distally to the plantar plate? Hsi and colleagues concluded that one should place the pad proximal to the metatarsal head and just distal to the distal edge of the orthotic.7 Hayda and co-workers found that distally placed, small, felt metatarsal pads reduced the most pressure on metatarsal heads.8 The shape, material and size of the metatarsal pad may have some effect on relief as well.

Comments

This is an important article as a large percentage of patients with lesser metatarsal pain present with biomechanical issues such as functional equinus, hypermobile first ray, forefoot supinatus/midtarsal joint dysfunction.

It is essential to focus on the midtarsal joint as failure of the midtarsal joint to lock by maximally pronating as propulsive phase is entered is a common finding in such patients. Careful attention to forefoot posting of the orthotic device is required. The forefoot to rearfoot assessment required for orthotic design needs to include assessment with any forefoot supinatus reduced. Forefoot valgus posting and reverse Morton's extensions are commonly used. I like metatarsal elevations pressed into the shell of the orthotic devices and may supplement that with a soft extension to advance the metatarsal support beyond the distal edge of the device.

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