Morton's Neuroma: Excerpt from Book 2 of Practical Biomechanics for the Podiatrist

The following is an excerpt from my book on Practical Biomechanics for the Podiatrist. 

https://store.bookbaby.com/book/practical-biomechanics-for-the-podiatrist1

 

Schematic of Morton’s Neuroma

 

     The basic mechanics of Morton’s Neuroma formation is pretty common knowledge. The junction of the medial plantar and lateral plantar nerves come together between the third and fourth metatarsals possibly making this nerve thicker or more sensitive. The motion of the 3rd metatarsal which articulates with the 4th metatarsal, and the motion of the 4th metatarsal which articulates with the cuboid, can be different enough that the intermetatarsal nerve branch can get irritated with the independent motion of the 3rd and 4th metatarsals. The overall motion of pronation always increases the metatarsal motion adding to the possibility of Morton’s Neuroma pain. If the nerve is already hypersensitive from low back issues or piriformis syndrome, or excessive pronation at the ankle with bowstringing of the posterior tibial nerve at the medial malleolus, or traction from over strengthening of the popliteal nerve with hyperextension of the knee, etc, then the pain can come on easily and with more disability. Morton’s neuroma pain, along with low back issues, etc, is called double crush syndrome. I have patients where triple and quadruple crush were in play with their presenting nerve pain. It is so common to have L4/L5 nerve root issues that cause pain around the 3rd intermetatarsal space with or without a neuroma. You always have to treat the foot, but you always have to be aware that nerves are superhighways to the brain. They get irritated anywhere along the chain from the foot to the skull, and nerve pain can be the worst pain people have to deal with. The opioid epidemic is one aspect that gives us perspective into this complex problem, because with bad nerve pain, patients many times feel they have no other choice. When the nerve pain starts at the foot, or the foot is just part of the picture, it is so important to be successful in treating each area. I tell my patients that the two things I hate the most as a podiatrist are nerve pain and infections because both are treatable, but possibly life changing if I fail.  
     The treatment of Morton’s Neuroma pain must always be 5 pronged (even though we are just focusing on the mechanics in this book): mechanical, inflammatory, neurological, diagnostic, and as a team (physiatrists, neurologists, pain specialists, etc.). The last point on nerve issues that I want to make is that nerve problems present in one of 3 ways: numbness, numbness and pain, or just pain. These 3 presentations are the same process that responds to treatments the same, even though patients respond and react to these 3 situations differently. The treating doctor should respond and treat them the same.

 

Schematic of how foot pain can be caused or heightened in intensity by back problems

 https://youtu.be/E0E60NpOSHg   Nerve Pain Video 

     To tie this into Chapter 3 and 4 on gait and biomechanical examinations, when a patient presents with Morton’s neuroma symptoms, the most important examinations to do in 10 minutes (or 20 minutes) are:

• Gait Findings of Pronation

• Gait Findings of Limb Length Discrepancy that puts stress on low back

• Gait Findings of Knee Hyperextension

• Forefoot to Rearfoot Alignment

• Metatarsal Alignment

• Ankle Joint Dorsiflexion for equinus forces to be reversed

          Other Special Tests
         

• Straight Leg Test for sciatica

• Tinel’s Test for Tarsal Tunnel Syndrome

• Wide Feet (or at least wider than shoes)

 

Common Mechanical Changes for Morton’s Neuroma/Neuritis (with the common ones utilized in RED)

1.  Metatarsal Padding

1. Orthotic Devices emphasizing Metatarsal Support

1. Forefoot Off Weighting

1. Soft Tissue Mobilization

1. Toe Separators

1. Buddy Taping

1. Neural Flossing

1. Metatarsal Doming

1. Standing Strengthening Exercises

1. Rocker Shoes, Carbon Plates, Bike Shoes with Embedded Cleats

1. Budin Splints

1. Sciatic Nerve Advice

1. Skip Lacing

1. Wide Shoes

 

     Metatarsal Padding for support of the metatarsals will stabilize the area and separate the metatarsals so the nerves do get irritated. Its mechanical function is to off weight the sore area, separate the metatarsals for less nerve entrapment (spreading the metatarsals), and transfer weight more proximal back towards the heel when standing. This is explained in the metatarsalgia section above. The main difference over metatarsalgia is that nerves probably can take a little less pressure initially then if there were no nerves involved, and then get used to more, and the placement may be slightly more medial for metatarsalgia. The nerves can be so red hot that they can not take any pressure, and this indicates they need a lot of nerve treatments at this point: orals and topicals, neural flossing, local and spinal injections, etc.
 
Practical Biomechanics Question #245: Nerves can be both helped and irritated by metatarsal pads. Since classic Morton’s neuromas usually love metatarsal pads, what would it indicate in terms of treatment direction if the metatarsal pads proved very irritative and intolerable?
 

Classic Longitudinal Metatarsal Pads for Morton’s Neuroma Pain (Hapad, Inc)

 

     Orthotic Devices emphasizing Metatarsal Support was also discussed in the metatarsalgia section. Its mechanical function is to off weight the sore area, support proximally, spread out the metatarsals to decrease entrapment, shift the weight more proximal while standing, and immobilize the foot somewhat for less motion. Certain feet, if supported well, will give the patient wonderful metatarsal support (like most pes cavus foot types). I find the classic Root Balance technique to be great in general for its emphasis on metatarsal support. Any orthotic laboratory should be able to give you advice on corrections to the impressions that will maximize the metatarsal support, the same as giving advice on corrections for lateral arch stability or medial arch stability. With Morton’s Neuromas, we want to maximize the intrinsic metatarsal support the impression can give us, and when needed, begin to add additional extrinsic metatarsal padding. This improved metatarsal support, especially when it is intrinsically applied, can make an incredible difference in support of the tissues involved. Support means stability or immobilization of the sore tissue.
     This all sounds nice, and is true, but the crowding of the shoe caused by an orthotic device and its added pads, etc, may not be tolerated in most shoes. For each patient, one variable may prove the most important for both helping and producing distress. I have had to abandon more shoes due to Morton’s neuroma conditions than any other problem.

 

Crazy Shoe Searches with Neuroma Pain

     Forefoot Off Weighting is initially applied with ⅛ inch adhesive felt, and then other types of glued material like Spenco, poron, or grinding rubber, to make it more permanent once the correct position for maximum pain relief. Its mechanical function is to off weight the sore area. For most cases of Morton’s neuromas, this will be under the 1st and 2nd metatarsal heads, and the 5th and somewhat 4th metatarsal heads. The process is started at the first visit with the adhesive felt. The patient is given more material with instructions to experiment. Occasionally the position that brings the most relief is not anticipated. If you can find the most sensitive spot plantarly, you can mark it with lipstick and have the patient transfer that spot onto the top of any surface to find the exact spot to float (off weight). When patients present to my office with previous orthotic devices, I always do this to make sure the accommodations are really in the correct spot, which they normally are not. Millimeters count here.

 

This patient with Morton’s Neuroma pain felt relief with this combination of metatarsal pads, off weight pads, and full length pads

 

Practical Biomechanics Question #246: Due to the fact that Morton’s Neuromas do not like tight shoes, every pad must be carefully tested for both positive and negative results. What are some options to help patients when the shoe and insert combination are helpful, but after hours of wear the neuroma starts to hurt due to the crowding?
 
     Soft Tissue Mobilization is an incredible help in releasing trapped nerves. Its mechanical function is to improve soft tissue mobility for less nerve entrapment. I apologize for forgetting the name of the podiatrist that initially turned me on to this twenty five years ago for I owe him a thank you. I not only have patients do self mobilization three times a day with topical nerve creams, like Neuro-Eze or Neuro-One (both L-Arginine based), with the goal to move the metatarsals around, but a prescription for physical therapy for soft tissue mobilization is typically given for 8 visits. At the same time, I have the therapist advise the patient on a sciatic nerve program and teach neural flossing or gliding. Also, instructions for the TENS unit daily program are occasionally given to the therapist.
 
Practical Biomechanics Question #247: How does foot rigidity cause or aggravate Morton’s Neuroma pain?

Soft Mobilization can be with a professional or self directed

 

Toe Separators are a simple, but sometimes very powerful, tool to change the biomechanics of nerve irritation. Its mechanical function is to change the dynamics of the nerve pressures. There are very thin wafer-like toe separators, but I prefer the normal small gel hourglass shaped ones. Since Morton’s Neuromas are typically between the 3rd and 4th metatarsals, these toe separators are placed between the 3rd and 4th toes. It seems like 50% of patients think it is helpful. This was taught to me by Dr. Remy Ardizzone.

 

     Buddy Taping of either the 2nd and 3rd toes, or the 3rd and 4th toes, when there was Morton Neuroma pain, seems to work the 50% of the time that toe separators do not. Its mechanical function is light immobilization of the tissues involved. I typically use 1 inch wide Coban or Coflex which sticks to itself and not the skin.

Here the 3rd and 4th toes are Buddy Taped 

     Neural Flossing or Gliding is a way to stretch and relax the sciatic nerve as it comes off the back, through the piriformis, down the hamstrings, splitting behind the knee to go into the back of the calf and side of the lower leg, and finally onto the top and bottom of the foot. Its mechanical function is to gently floss the nerve making sure that there is no swelling or scar adhesions. There are many variations. Some of the variations will excite the nerve more, and some will work better on the peroneal nerve or the posterior tibial nerve. The standard floss is where the patient lies on their back with the resting leg bent at the knee and the foot flat on the ground or yoga mat. The side to be moved starts where everything is flexed as much as possible (toe dorsiflexed, ankle dorsiflexed, knee flexed and hip flexed without pulling pelvis off the table). Then 10 rhythmical rotations slowly and gently are started from flexed to extended (hip extended, knee extended, ankle plantar flexed, and toes pointed), never stopping at either end of the exercise. Nerves hate prolonged stretches and love motion. Neural Flossing is typically done 3 times a day, on a hard surface since you need to have the pelvis and spine as stable as possible. I will talk in a minute about standard sciatic nerve advice.

 

 

Neural Flossing of the Right Leg with the Stable Leg Side Immoble. Here the right leg is already starting to straighten where the left leg is anchored to the supporting surface.

 

Neural Flossing of the Right Side starts with the right hip, knee, ankle and toes pulled up, and then gradually these 4 joints are pointed

 

Practical Biomechanics Question #248: Neural Flossing is 10 slow flexions and extensions. What puts more stress on the sciatic nerve: Knee Straight vs Knee Bent?
 
     Metatarsal Doming was previously discussed in the big toe joint section. Its mechanical function here is to make the foot more stable taking stress off the nerves.

Metatarsal Doming is an Isometric with 6 second contraction 4 second relax

 

     Standing Strengthening Exercises, along with metatarsal doming, will help keep the injured tissue strong. Its mechanical function is to increase stability by strength. We have to avoid toe bend exercises due to the location of the pain (like heel raises, planks, downward dogs, etc.), but the many versions of Single Leg Balancing, and standing poses in Yoga, Chi Gong, and Tai Chi are a wonderful way to maintain strength which avoid toe bending. Other modifications can be done to cardio workouts like staying flat footed while doing the elliptical, or having the pedal in the arch or heel on a stationary bike.

Single Leg Balancing to help develop Intrinsic Foot Strength

 

     Rocker Shoes have been previously discussed in the big toe joint section. You probably should also consider Bike Shoes with Embedded Cleats and Carbon Plates when immobilization seems necessary to bring the pain down between 0-2.

 

Hoka One One Rocker Shoes

     Budin Splints were previously discussed in the hammertoe section. Its mechanical function is to immobilize the motion of the local nerves. For Morton’s Neuromas, they change the biomechanics of the stresses in the area. Typically I use a Single Loop Budin Splint (also called hammer toe regulator) and get equal results by buddy taping 2 and 3 or 3 and 4 with Coban tape. In several cases of Morton’s Neuroma with a really sore 3rd toe, the patients may find the biggest relief over the 2nd toe only, over the 4th toe only, or getting a double loop for the 2nd and 4th toes combined. This is a way to indirectly immobilize the local nerve. Budin Splints are primarily immobilizing the metatarsal phalangeal joints, and you can add metatarsal padding to the bottom of the splint to off weight the sore areas also.

 

Here a Budin Splint is placed over the 3rd toe for Morton’s Neuroma pain with a small Hapad metatarsal pad. This is ideal for using the previously discussed lipstick marked on the sore spot to find the exact location of the pad

 

     Sciatic Nerve Advice is needed for any nerve condition you treat including Morton’s Neuromas. Its mechanical function is to find ways to decrease the stress on the nerve like various positions. Nerve irritation affecting the foot can come from anywhere. The nerve can be irritated from the exhausting long hours the patient sits. The nerve can be irritated from a bad mattress. The nerves can be irritated by the lifting or torqueing at their jobs. A simple prescription to a physical therapist for a sciatic nerve program should be all you need. However, tests including straight leg, Tinels, intermetatarsal nerve sensitivity on exam, can be retested for improvement evaluation, and point to how high the nerve tension is on the body. I try to discuss what is nerve sensitivity with the patient, so they know what to report. Nerves can hurt for sure, but also give symptoms of burning, itching, buzzing, tingling, prickling, sharp stabs, and numbness. I want to know where and when they have any other nerve symptoms called dyskinesias, even if it is the upper extremity, since I am looking for patterns or overall neural tension in the body. We all know that we must bend our knees when we are picking up something. The worst stretch on the sciatic nerve is when the ankle is bent (dorsiflexed), the knee is straight, and the hips are bent forward. Even having 2 of these together can be a problem, especially straight knees and dorsiflexed ankles. What position are we in when lowering our heels off a stair? Or doing the downward dog? These are positional questions you expect a good physical therapist to know and change as they evaluate a patient’s routine.
     This is a good time to remind the reader that Physical Therapists do have a subspecialty in nerves. There is an Academy of Neurologic Physical Therapists. Have your patients with nerve pain see if various offices have therapists specializing in the nervous system.
 
Practical Biomechanics Question #249: Nerve pain, like that of Morton’s Neuroma, has many mechanical treatments. Name 4 mechanical treatments for intermetatarsal nerve pain.
 
     Skip Lacing is a common way to take pressure off an area, even when the pain seems all plantar. Its mechanical function is to decrease compression across the sore area. Nerves hate compression. Typically I will remove the lacing from the distal eyelet,  but occasionally two. 

 

2 eyelets are removed to reduce pressure temporarily across the metatarsophalangeal joints

 

Wide Shoes really produce the same effect as the skip lacing. Its mechanical function is to prevent medial to lateral compression forces on the intermetatarsal nerves. New Balance was the first company for me that really helped with their variety of shoe widths. Now other companies at least have several widths per size. Then there are shoes that just run wide like Keen, Lems, Altra, etc.

 

Practical Biomechanics Question #250: Any foot nerve pain should be assumed that the symptoms are at least partially coming from higher up the chain. If a patient presents with Morton’s Neuroma pain, but presents with numbness on the top front half of their foot, where does some (or all) of the problem arise from?

     I will close with a copy of my Nerve Pain Algorithm for treatment options for peripheral neuropathy, Morton's Neuromas, Tarsal Tunnel, Baxter's Nerve Entrapment, etc