Connecting Biomechanics and Morton’s Neuroma



Morton's Neuroma

The term ‘neuroma’ refers to the swelling or thickening of a nerve tissue in any part of the body. The continual compression or stretching of the nerve could eventually lead to permanent nerve damage, which is why the treatment of neuroma is of the utmost importance.

The most common site for a neuroma is the foot, particularly in the ball of the foot between the third and fourth metatarsal bones. This is called Morton’s Neuroma, and the affected interdigital nerve is microscopically seen to have extensive concentric perineural fibrosis.

The interdigital neuroma (as it is sometimes called) occurs in the nerve at the distal end of the metatarsal bone, just before the nerve divides itself into two branches. At the level of the metatarsal heads, the interdigital nerve traverses inferior to the intermetatarsal ligament. At this site, repetitive irritation to the interdigital nerve causes an enlargement of its protective sheath in the foot and the formation of a neuroma. 

Any puncture wounds or lacerations can also cause injury to the nerve, forming a traumatic neuroma in the process.

The neuropathic pain associated with the condition is often described as a burning or shooting pain in the forefoot. There may also be a tingling sensation or numbness in one or two of the metatarsal heads.

Patients often feel like removing their shoes and rubbing the ball of the foot to ease the pain.

Among the biomechanical factors responsible for Morton’s Neuroma, hyperpronation plays a significant role by causing the forefoot to become unstable, and the metatarsal heads to rotate slightly.

The constant pinching of the interdigital nerve by the metatarsal heads on rotation enlarges the nerve sheath, ultimately leading to the development of a neuroma.

With changes to the position of the hip, knee or pelvis brought on by hyperpronation, there is alteration in the way the foot interacts with the ground. This often results in metatarsal instability. Instability of the first metatarsal, leads to insufficient pressure in the big toe joint and consequently, an overload of stress on the adjacent metatarsals and the interdigital nerve.

In order to successfully treat the condition, it becomes vital to reduce the excessive force on the affected nerve by correcting the biomechanical abnormalities through the use of custom made orthotics such as the MASS4D® foot orthotics.

These full contact orthotics provide the support needed for the foot to reduce compression on the interdigital nerve, giving it time to heal itself by spreading the metatarsals apart and taking the pressure off the neuroma.

Related Links

References:

  1. Stephen M. Pribut (2003) Morton’s Neuroma: Cause and Treatment. American Academy of Podiatric Sports Medicine. Retrieved from http://www.aapsm.org
  2. Kevin Barry (2016) Physical Medicine and Rehabilitation for Morton Neuroma. Medscape. Retrieved from http://emedicine.medscape.com/

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