Metatarsalgia

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Definition/Description

Metatarsalgia : It’s a general term used to denote a painful foot condition in the metatarsal region of the foot (the area just proximal the toes, more commonly referred as the ball-of-the-foot). This is a disorder that can affect the bones as well as joints at the plantar forefoot.

Metatarsalgies are often accompanied by excessive callus formation over a bony protrusion, and there is severe pain and sensitivity to pressure around the callus.[1,2]

Clinically Relevant Anatomy

The most important anatomy is the bone structures of the forefoot, to be exact the metatarsals. The metatarsals are proximally connected to the tarsal bones and distally to the bones of the toes, the phalanges. The joints between the metatarsals and the first phalanx is called the metatarsophalangeal joint (MTP). These joints form the ball of the foot, and movement in these joints is very important for a normal walking pattern. Of course a knowledge of the other foot bones and structures (muscles, tendons, ligaments,…) is also necessary to distinguish the sctructures and pathologies.
More information about the human anatomy you can find by clicking on the link under references.

Epidemiology /Etiology

There is important variability in possible causative factors, but a majority seem to be related to foot and ankle deformity. This can lead to a fundamental etiological component of metatarsalgia; the repetitive loading of a locally concentrated force in the forefoot during gait.

Metatarsalgia is most often localized to the first metatarsal head (the ball of the foot just behind the big toe). The next most frequent site of metatarsal head pain is under the second metatarsal. This can be due to either a too short first metatarsal bone or to "hypermobility of the first ray" (metatarsal bone medial cuneiform bone behind it), both of which result in excess pressure being transmitted into the second metatarsal head.[2,3,4]
One or more of the metatarsal heads become painful and/or inflamed, usually due to excessive pressure. It’s common to experience acute, recurrent, or chronic pain with metatarsalgia. The pain is often caused from improper fitting footwear, most frequently by women dress (high heel) shoes and other restrictive footwear (figure1:overcompression around the metatarsal heads can be related to metatarsalgia) [6]. Footwear with a narrow toe area forces the ball-of-foot area to be forced into a minimal amount of space(latero-medial over compression). This can hamper the walking process and lead to extreme discomfort in the forefoot. [5,9]
Other factors that can cause excessive pressure are: participating in high impact activities without proper footwear and/or orthotics; older age, the pad in the foot tends to thin out making it much more susceptible to pain; an imbalance in the length of the metatarsals; disturbances in gait, in morphology of the foot (a too long bone that protrude to the bottom of the foot) and a too short Achilles tendon.

Norman Espinosa divided metatarsalgia into three categories in his review. He listed the various conditions associated with each subtype.   The primary metatarsalgia refers to symptoms arising from innate abnormalities in the patient’s anatomy leading to overload of the affected metatarsal. According to Jesse F. Doty, metatarsophalangeal joint instability of the lesser toes (mainly due to plantar plate insufficiency) is also a common cause of metatarsalgia.  Secondairy metatarsalgia can be caused by systemic conditions such as arthritis of the MTP joint. And lastly, iatrogenic metatarsalgia can occur after (failed) reconstructive surgery.

Characteristics/Clinical Presentation

Metatarsalgia typically affects the bottom of the second metatarsophalangeal joint (where the second toe joins the foot). However, any of the other metatarsals can be affected.In more unusual cases, more than one metatarsal can be affected on one foot. When metatarsalgia affects the second metatarsophalangeal joint, it also sometimes called “second metatarsophalangeal stress syndrome”.

Metatarsalgia is defined as pain in the anterior segment of the foot. Viladot stated that it is one of the most common types of pain. Symptoms of metatarsalgia include : pain and tenderness of the plantar surface of the heads of the metatarsal bones or of the metatarsophalangeal joint, development of callus under the prominent metatarsal heads, and increased pain during the mid- stance and propulsion phases of walking as body weight is shifted forward onto the forefoot.

The pain typically feels like a deep bruise. Sometimes, it will feel like there is a rock under the ball of the foot. These symptoms are usually worse when walking or standing barefoot on a hard surface or poorly cushioned shoe, and better when in well-cushioned shoes. At the end of a day with substantial standing and/or walking, the area can throb a bit.

When a patient complains of forefoot pain, the first thing is to observe is whether a callus is present. The subjective findings include pain under the head of the metatarsal, often with individual of multiple contracted digits. There may be tenderness over the plantar surface of the metatarsals. There may also be a depression on the dorsum over the head of the metatarsal bone. There may be a decreased passive range of motion of the involved metatarsophalangeal joint.

It is not uncommon to have a callus located under the affected metatarsal. Pain usually is first noticed at the bottom of the ball of the foot and there is no swelling. With progression, swelling can appear, along with tenderness at the top side of the joint. In some cases, bursitis will form adjacent to the metatarsal. In even more advanced cases, the joint capsule and ligaments on the bottom of the joint can wear out and rupture, leading to the progressive development of a hammertoe.  Prof. Espinosa found that claw-toes with synovitis or even subluxation of the MTP joints were a common finding. 

Differential Diagnosis

Twenty-three different diagnoses were made for people with pain in the fore part of the foot. These diagnoses were grouped in three main headings: primary metatarsalgia, secondary metatarsalgia and pain under the fore part of the foot. The following table shows the different diagnoses devided under the three main catogories.

A study of metatarsalgia in 98 patients revealed 23 distinct diagnoses. Four of these diagnoses are mentioned below. Scranton divided metatarsalgia into structural, systemic, and miscellaneous forefoot pain categories. Structural and postoperative etiologies were the most common causes of forefoot pain; however, rheumatoid arthritis, Morton’s neuroma, and sesamoiditis were also relatively common. Although the great percentage of pain in the forefoot, especially under metatarsal heads, is caused by callosities, the most common of these diagnoses will be considered.  

1. Plantar fasciitis 

2. Morton's Neuroma 

3. Morton's toe 

4. Systemic arthtritis 

Diagnostic Procedures

To differentiate the one diagnose from the other the use of the patient’s history, physical exam, roentgenograms, cholesterol-crystal force-plate analysis, intra-articular/digital injections and additional laboratory studies (electromyography, arteriograms, venograms,..) are used.

The primary cause for metatarsalgia is repetitive application of excessive force to one metatarsal area more than the others. The second metatarsal is most commonly affected typically because there are a number of factors that can lead to excess force on that bone/joint area.
Factors that can lead to metatarsalgia:
Metatarsal bone longer than the others, Metatarsal bone lower than the others, Adjacent unstable first metatarsal, Adjacent bone higher than the others (transfer loading), Associated hammertoe, Tight calf muscle, High heeled Shoes, Shoes with inadequate cushioning, Overweight, Overuse.

W. Yoo describes metatarsalgia as pain localized to the forefoot.  Forefoot pain may be caused by conditions of the lesser toes themselves (eg, hammertoes, mallet toes, claw toes). The pathophysiology of lesser toe deformities is complex and is affected by the function of intrinsic and extrinsic muscle units. In addition to lesser toe and metatarsal abnormality, forefoot pain can be attributed to interdigital neuritis, disorders of the plantar skin, and gastrocsoleus contracture. 

Outcome Measures

• Foot Function Index (FFI) 
The Brazilian-Portuguese version of the FFI questionnaire was found to be a valid and reliable instrument for foot function evaluation, and can be used both in scientific settings and in clinical practice.
Martinez, Bruna Reclusa, et al. "Validity and reliability of the Foot Function Index (FFI) questionnaire Brazilian-Portuguese version." (2016)
→ Level of evidence: 2B

• Foot Posture Index (FP1-6)
No scientific evidence found correlated to metarsalgia

• Manchester-Oxford foot questionnaire (MOxFQ) 
Haque, Syed, et al. "Outcome of Minimally Invasive Distal Metatarsal Metaphyseal Osteotomy (DMMO) for Lesser Toe Metatarsalgia." Foot & ankle international (2015) → Level of evidence : 4

Examination

Look for evidence of systemic disease especially:
• diabetic neuropathy
• inflammatory arthropathy
• neurological disease
• vascular disease
Examination must begin proximally
• any stiffness or deformity (including length discrepancy) which might alter pressures on the forefoot?
• tight Achilles tendon or reduced ankle dorsiflexion, especially if there is fixed equinus (remember to examine in subtalar neutral position)
• pes cavus
• overpronated foot with unstable 1st ray
• peripheral neurological examination
• tenderness or a positive Tinel sign over the major nerve trunks
• hallux deformity or painful 1st MTPJ
• hammer or claw toes - if so, how flexible is the MTPJ. With the MTPJ reduced (if possible) is the fat pad reduced under the metatarsal heads?
• interdigital tenderness, palpable swelling or a positive metatarsal head compression test or Mulder's click
• interdigital corns
• tenderness and/or calluses under the metatarsal heads - check the relationship between the relative positions of heads and calluses. Most calluses are relatively diffuse although there may be increased thickening under the MT heads. However, a very localised callus should raise suspicions of a plantar condylar eminence
• metatarsophalangeal instability or irritability
• it is often possible to assess the relative heights and lengths of metatarsals by palpation
• look for scars of previous surgery
Always screen the patient for diabetes - a urine test is usually enough
This will usually indicate one or more possible factors which may be contibuting to forefoot pain. Differential injections around interdigital nerves and into MTP joints may help distinguish between MTP synovitis and interdigital neuralgia (although at least 10% of patients with each of these conditons also has the other) (Miller 2001). In the end it often requires experience-based judgement to decide which factors should be tackled and in what order.

For second metatarsophalangeal joint instability, Dotty and Jesse F. devided the clinical staging of examination findings in 4 grades: 

• Grade 0: No MTP joint malalignment; prodromal phase with pain but no deformity
  → Physical Examination Findings: MTP joint pain, thickening or swelling of the MTP joint, diminished toe purchase, negative drawer test result.

• Grade 1: Mild malalignment of MTP joint; widening of web space, medial deviation

→ Physical Examination Findings: MTP joint pain, swelling of MTP joint, reduced toe purchase, mildly positive drawer test result (<50% subluxated).

• Grade 2: Moderate malalignment; medial, lateral, dorsal, or dorsomedial deformity, hyperextension of MTP joint

→ Physical Examination Findings: MTP joint pain, reduced swelling, no toe purchase, moderately positive drawer test (>50% subluxated).

• Grade 3: Severe malalignment; dorsal or dorsomedial deformity; second toe can overlap hallux; might have flexible hammertoe

→ Physical Examination Findings: Joint and toe pain, little swelling, no toe purchase (can dislocate MTP joint), flexible hammertoe.

Medical Management

Unloading pressure to the ball-of-the-foot can be accomplished with a variety of footcare products. Orthotics designed to relieve ball-of-foot pain usually feature a metatarsal pad. The orthotic is constructed with the pad placed behind the ball-of-the-foot to relieve pressure and redistribute weight from the painful area to more tolerant areas. Other products often recommend include: gel metatarsal cushions, metatarsal bandages, NSAID’s, such as ibuprofen ; however, these agents rarely provide a long-term solution. NSAIDS are most commonly used for the relief of mild to moderate pain. But you have to use the right shoes. [4,7]

Physical Therapy Management

The treatment is initially non conservative. The pressure on the forefoot can be reduced by stretching exercises to perform at the level of the lower limb, amounting. Also custom-made orthopedic insoles can reduce pressure.
Sometimes, in very specific cases, an infiltration, followed by taping a few weeks, brings some comfort, also some mobilization exercises are recommended. [2]

Gajdosic and coworkers demonstrated that a 6-week stretching program increased the maximal ankle dorsiflexion angle and length extensibility. They further demonstrated that stretching enhances the dynamic passive length and passive resistive properties.  - level of evidence 1b. 

If these treatments have insufficient impact, surgery may be considered, depending on the defects, causes. In cases of hallux valgus or varus position, it should also be surgically corrected. The most common procedure is an osteotomy, where the metatarsal (one or more) responsible for the excess pressure, is shortenend or lifted. After surgery, one can basically rely on an immediate postoperative specifically designed shoe.[2,4,5]

Distal metatarsal osteotomies (such as The Weil osteotomy) provide a longitudinal decompression and is particularly relevant in patients suffering from metatarsalgia due to an excessively long metatarsal. One problem is the plantar translation of the metatarsal head during shortening.  - level of evidence 3a . Based on those results, Maceira and coworkers introduced the so-called “triple-osteotomy”. This modified osteotomy affords precise and accurate shortening of the metatarsal without unwanted plantar translation of the heads. The triple osteotomy also preserves the relationship between the dorsal interossei and transverse axis of rotation of the MTP joint to avoid an extension deformity.  - level 4 evidence. 

Other Treatment
The high pressure under the metatarsal heads can be reduced by applying metatarsal pads. In a double-blind study, tear-drop shaped, polyurethane metatarsal pads were applied by experienced physiatrists to a total of 18 feet. As a result, there were significantly decreased maximal peak pressures and pressure time intervals during exercise that correlated with better pain and function outcomes. [2,8]

Espinosa stated (with 2 clinical studies (level 2A evidence) and 1 retrospective study (level 2B evidence) as reference) that generally, accommodative insoles may redistribute pressure under the foot while functional orthoses are intended to control abnormal intersegmental motion. But both of them may be useful in the non-operative management of metatarsalgia.

Not much scientific literature exists to confirm the effectiveness of these conservative treatment for the treatment of central metatarsalgia. Nevertheless, such measures often meet with success and have the additional benefit of not compromising future treatment 

Key Research

Espinosa, Norman, Ernesto Maceira, and Mark S. Myerson. "Current concept review: metatarsalgia." Foot & ankle international 29.8 (2008).
Level of evidence: 1a

Resources

1. The use of collagen injections in the treatment of metatarsalgia: A Case Report http://www.jfas.org/article/S1067-2516(10)00288-7/abstract
2. Sports medicine- metatarsalgia
http://emedicine.medscape.com/article/85864-overview

3. J.Gregg, P. Marks (2007). Australasian Radiology: Metatarsalgia: An ultrasound perspective. The Royal Australian and New Zealand College of Radiologists. Pages 493-499.
4. Associatie orthopdedie Lier http://www.associatie-orthopedie-lier.be/Generic/servlet/Main.html;jsessionid=B2F5539057DBEF99F23742666B6A844C?p_pageid=37247
5. Foot and ankle institute http://voetenenkelinstituut.be/aandoeningen/voorvoet/metatarsalgie/
6. Figuur: http://www.sunnybrook.ca/uploads/metatarsalgia.jpg
7. Treatment & medication
http://emedicine.medscape.com/article/85864-treatment

8. Walter R. Frontera, Julie K. Silver, Thomas D. Rizzo (2008). Essentials of Physical Medicine and Rehabilitation. Elsevier Health Sciences. Pages 461-475
9. Metatarsalgia- forefoot pain
http://www.sportsinjurybulletin.com/archive/metatarsalgia.html

10. Figuur: http://www.sportsinjuryinsurance.co.uk/foot1.htm

Clinical Bottom Line

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References

1. Doty, Jesse F., and Michael J. Coughlin. "Metatarsophalangeal joint instability of the
lesser toes." The Journal of Foot and Ankle Surgery 53.4 (2014): 440-445.
(level of evidence: 2a)
2.Espinosa, Norman, Ernesto Maceira, and Mark S. Myerson. "Current concept review:
metatarsalgia." Foot & ankle international 29.8 (2008)
(level of evidence: 1a

3.G. McPoil Thomas and Schuit Dale. “Management of metatarsalgia secondary to
biomechanical disorders”. Physical Therapy 66(6): 970-2; July 1986
(level of evidence: 3c)
4. Sobel Ellen, D.P.M., Ph. D., C.PED. and Levitz Steven, D.P.M.; “Metatarsalgia : Diagnosis
and Manangement, Etiologies and Differential diagnoses”. Podiatry Management
(level of evidence: 5)
5 . Britt A Durham, Metatarsalgia Treatment & Management, medscape,2012
(level of evidence: 5)
6. W Yoo, Effect of the Intrinsic Foot Muscle Exercise Combined with Interphalangeal
Flexion Exercise on Metatarsalgia with Morton’s Toe, 2014, Pubmed
(level of evidence:3b)
7. Hashimoto T, Sakuraba K.: Strength training for the intrinsic flexor muscles of the foot:
effects on muscle strength, the foot arch, and dynamic parameters before and after the training. J
Phys Ther Sci, 2014, 26: 373–376. ,pubmed
(level of evidence: 5)
8. Med Clin North Am. 2014 Mar;98(2):233-51. doi: 10.1016/j.mcna.2013.10.003. Epub
2013 Dec 10. Metatarsalgia, lesser toe deformities, and associated disorders of the forefoot.
(level of evidence: 4)
 9. Gajdosik, RL, et al., A stretching program increases the dynamic passive length and passive
resistive properties of the calf muscle-tendon unit of unconditioned younger women. Eur J Appl
Physiol.
(level of evidence: 1b)
10. Maceira, E. et al, Analisis dela rigidez metatarso-falangica en las osteotomias de Weil.
Revista de Medicina y Cirugia del Pie.
(level of evidence: 3a)

12. Espinosa, Norman, Ernesto Maceira, and Mark S. Myerson. "Current concept review: metatarsalgia." Foot & ankle international 29.8 (2008) (level of evidence: 2a)

13. G. McPoil Thomas and Schuit Dale. “Management of metatarsalgia secondary to biomechanical disorders”. Physical Therapy 66(6): 970-2; July 1986 (level of evidence: 3c)

14. Sobel Ellen, D.P.M., Ph. D., C.PED. and Levitz Steven, D.P.M.; “Metatarsalgia : Diagnosis and Manangement, Etiologies and Differential diagnoses”. Podiatry Management (level of evidence: 5)

15. Britt A Durham, Metatarsalgia Treatment & Management, medscape,2012 (level of evidence: 5)

16. W Yoo, Effect of the Intrinsic Foot Muscle Exercise Combined with Interphalangeal Flexion Exercise on Metatarsalgia with Morton’s Toe, 2014, Pubmed (level of evidence:3b)

17. Hashimoto T, Sakuraba K.: Strength training for the intrinsic flexor muscles of the foot: effects on muscle strength, the foot arch, and dynamic parameters before and after the training. J Phys Ther Sci, 2014, 26: 373–376. ,pubmed (level of evidence: 5)

18. Med Clin North Am. 2014 Mar;98(2):233-51. doi: 10.1016/j.mcna.2013.10.003. Epub 2013 Dec 10. Metatarsalgia, lesser toe deformities, and associated disorders of the forefoot. (level of evidence: 4)

19. Gajdosik, RL, et al., A stretching program increases the dynamic passive length and passive resistive properties of the calf muscle-tendon unit of unconditioned younger women. Eur J Appl Physiol. (level of evidence: 1b)

20. Maceira, E. et al, Analisis dela rigidez metatarso-falangica en las osteotomias de Weil. Revista de Medicina y Cirugia del Pie. (level of evidence: 3a)