Orthotics can be a vital part of treatment for the sometimes vague diagnosis of metatarsalgia. Accordingly, this author expounds on the benefits of orthotics and accommodations such as metatarsal pads and bars for metatarsalgia arising from conditions such as lesser metatarsophalangeal joint instability.
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On a daily basis, podiatrists see patients who complain of pain in the forefoot. Some are self-diagnosing patients who tell you they have metatarsalgia based on what they saw on the Internet. Depending on what you read, metatarsalgia is a symptom and not a diagnosis. What really is metatarsalgia?
Metatarsalgia is a non-specific term for pain in the forefoot. The generally accepted theory is that the pain is occurring in or near the metatarsal heads, the metatarsophalangeal joints (MPJs) or is caused by soft tissue injury. It can be a challenging problem because of the vagueness of the symptoms and the vast conditions it could encompass. The word “metatarsalgia” includes conditions such as Morton’s neuroma, stress fractures, predislocation syndrome/plantar plate tear, capsulitis, plantarflexed metatarsals, Freiberg’s disease, intermetatarsal bursitis, calluses secondary to hammertoes or clawtoes, and rheumatoid arthritis.1
Scranton found 23 different diagnoses of metatarsalgia in 98 patients.2 Forty-five patients had primary metatarsalgia, 12 of whom had static disorders and 12 of whom had iatrogenic (postoperative etiologies. Thirty-three patients had secondary metatarsalgia, 11 of whom had rheumatoid arthritis and 10 of whom had sesamoiditis. Twenty patients experienced pain under the forefoot.
Helal classified metatarsalgia as primary or secondary with primary metatarsalgia being an anatomic abnormality resulting in increased pressure under the metatarsal heads.3 Examples include short or long metatarsals, hallux valgus, rigidus and first ray hypermobility. Secondary metatarsalgia is pain not originating within the metatarsal area. Secondary causes include Morton’s neuroma, rheumatoid arthritis, equinus deformities and Freiberg’s infraction.
Regnauld classified metatarsalgia as diffuse, localized, subcutaneous soft tissue and cutaneous.4 Scranton found that primary and secondary metatarsalgia can occur together.2 Nonetheless, one should determine the etiology and implement a focused treatment plan. Having a fundamental understanding of anatomy and biomechanics, and emphasizing a thorough history and physical can aid in identifying the diagnosis and creating that treatment plan. The mainstay in treating metatarsalgia is non-operative management.
Orthotics are key components in treating metatarsalgia and one can employ various orthotic modifications after identifying the underlying etiology. Manipulation, shoe modifications, injections and surgery are other treatment options clinicians can use with or instead of orthotics.
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Loss of shock absorption due to distal migration of the fat pad can expose the metatarsal heads to increased pain. This is more pronounced in the cavus foot type with digital contractures and increased declination of the metatarsal heads. The goals with orthotic therapy in this case are to decrease the shock and reduce the pressure on the metatarsal heads. One can accomplish these objectives by using a shock absorbing material such as Spenco, PPT or another material.
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.
Intractable plantar keratoses (see “Key Insights On Intractable Plantar Keratoses” at http://www.podiatrytoday.com/key-insights-intractable-plantar-keratoses [9] ) 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.
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
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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.
Lesser metatarsophalangeal (MPJ) joint instability is a common cause of metatarsalgia, specifically affecting the second MPJ. Predislocation syndrome, a term often used for this instability, is an acute, chronic or inflammatory condition that affects the MPJs, but the second MPJ is the most affected.
While there are various intrinsic and extrinsic structures that stabilize the joint, the plantar plate is the key anatomical structure. The inflammatory process causes attenuation of the structure, which leads to dislocation. Factors such as hallux valgus, metatarsus primus elevatus, an elongated second metatarsal and a hypermobile first ray can cause an overload of the second MPJ leading to instability.
Non-operative treatments include padding/strapping to reduce any retrograde pressure on the joint, NSAIDs, intra-articular steroid injections, orthotics and shoe modifications. When injecting steroids into the joint, rocker bottom shoe modifications are highly recommended to eliminate the propulsive phase of gait and reduce the possibility of further attenuation secondary to steroid injection. After confirming the diagnosis and identifying the etiology, one can implement the orthotic modification.
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If the etiology is an elevated first metatarsal, there are several options to address this and the goals should be to increase the ground reaction forces under the first metatarsal head and reduce lesser metatarsal overload. There are various options to achieve these objectives. These options include: a Morton’s extension; a first ray cutout with or without a reverse Morton’s extension in the second through fifth sub-metatarsals; a reverse Morton’s extension by itself; and a Cluffy wedge.
Controlling rearfoot pronation by increasing the subtalar joint supination moment with a medial heel skive or Blake inverted pour can help stabilize the first ray. Plantarflexing the first ray while casting for orthotics is an option but is controversial to some.
A 40-year-old male runner presented to the office with a two-week onset of swelling and pain in his right forefoot. He relates he had a second metatarsal stress fracture eight months ago and another one about a year before that. The patient was immobile in a surgical shoe for seven weeks before resolution of his symptoms. He enjoys running half marathons but his training has been reduced since then because of the initial stress fracture. The patient had participated in cross training via swimming and biking. He denies any change in his mileage, training surface or shoes. He also denies any acute episode of an injury.
Clinically, the patient had a pinch callus on the right hallux but no other hyperkeratotic lesions. He had exquisite tenderness over the second metatarsal with edema around the second and third metatarsal region. Pain was also present in the second intermetatarsal space but it was not as pronounced as it was over the second metatarsal. A mild to moderate dorsal bunion was present at the first MPJ.
The patient had approximately 40 to 45 degrees of dorsiflexion at the first MPJ on the right foot with no pain or crepitus. However, he had approximately 5 degrees of dorsiflexion with loading of the foot.His subtalar joint range of motion was normal and he had gastroc-soleus equinus. Gait evaluation demonstrated an abductory twist with early heel-off on the right side. The sock liners of his running shoes showed considerable wear under the right hallux and the lesser metatarsal area. The area under the first metatarsal showed very little wear.
Radiographs revealed a periosteal reaction along the neck of the second metatarsal with no displacement. There was metatarsus primus elevatus of the first metatarsal with no spurring off the dorsal first MPJ and no joint space narrowing. The metatarsal parabola was normal.
The treatment plan consisted of immobilization in a surgical shoe for six to eight weeks, aggressive gastroc-soleus stretching and molding for orthotics. His orthotic for the right foot consisted of a first ray cutout and a reverse Morton’s extension in an effort to increase the ground reaction forces to the first metatarsal head.
He resumed his running two months after the resolution of his symptoms. At his three-month orthotic check, I added an additional 1/8-inch of Korex to the reverse Morton’s extension. I have been able to follow him now for two years and he has not had any recurrence of his stress-related symptoms.
Metatarsalgia is similar to lower extremity edema. They are symptoms of other conditions but there is usually an underlying cause.
This article is not all-inclusive but is more of a broad overview and summary of some of the more common conditions included in metatarsalgia. Custom foot orthotics are an important component in treating metatarsalgia and podiatrists should be well versed in these accommodations.
With the decreased emphasis on biomechanics in the podiatry arena, if you are unsure of what accommodation to use and when, do not be afraid to use your orthotic lab for recommendations. Your patients will be rewarded.
Dr. Yakel is a Fellow of the American College of Foot and Ankle Surgeons, and is board certified by the American Board of Podiatric Surgery. He is an Associate of the American Academy of Podiatric Sports Medicine. Dr. Yakel practices in Longmont, Colo.
References
1. Coughlin MJ. Common causes of pain in the forefoot in adults. J Bone Joint Surg Br. 2000; 82(6):781–90.
2. Scranton PE Jr. Metatarsalgia: diagnosis and treatment. J Bone Joint Surg Am 1980; 62(5):723-732.
3. Helal B, Thomas N, Nissen KI. Disorders of the lesser ray. In Helal B, Wilson D (eds.): The Foot. Churchill Livingstone, New York, 1988, p. 486.
4. Regnauld B. The Foot. Springer-Verlag, Berlin, 1986.
5. Dananberg HJ. Manipulation of the ankle as a method of treatment for ankle and foot pain. J Am Podiatr Med Assoc. 2004;94(4):395-9.
6. Koenraadt, KL, Stolwijk NM, van den Wildenberg D, Duysens J, Keijsers NL. Effect of a metatarsal pad on the forefoot during gait. J Am Podiatr Med Assoc. 2012; 102(1):18-24.
7. Hsi WL, Kang JH, Lee XX. Optimum position of metatarsal pad in metatarsalgia for pressure relief. Am J Phys Med Rehabil. 2005; 84(7):514-520.
8. Hayda R, Tremaine MD, Tremaine K, Banco S, Teed K. Effect of metatarsal pads and their positioning: a quantitative assessment. Foot Ankle Int. 1994; 15(10):561-566.
For further reading, see “Can Orthotics Address The Faulty Biomechanics Of Metatarsalgia?” in the June 2005 issue of Podiatry Today.
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[2] http://www.podiatrytoday.com/volume-25-issue-4-april-2012
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[9] http://www.podiatrytoday.com/key-insights-intractable-plantar-keratoses
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