In Part 2 of Morton’s Neuroma treatment options, I am going to begin to dig a little deeper. We will start with discussing the components of a CFO that makes sense for our treatment, but we do not need to include them all.
The main goals of the Morton's Neuroma orthosis are to achieve overall stability in the foot, transfer weight off sore areas to non-sore areas, offload sore areas, and cushion the sensitive area(s). Now, let us look at getting this accomplished.
Components for a great Morton’s Neuroma orthosis:
- Balancing that gives the best metatarsal support and overall foot alignment
- Length of device ending at the surgical neck of the metatarsals to achieve as full metatarsal support as possible
- Intrinsic Metatarsal Arch 2-4, which will be part of our forefoot balancing
- Adjustable Metatarsal Arch (top cover glued only to heel)
- Metatarsal Support sulcus length 1st, 2nd and 5th as part of our off loading sore areas
- Metatarsal Bar
- Wide as possible for shoes and foot (dress orthotic devices normally 1 cm narrower than athletic)
- Lower heel contact maximally with selection of lower heeled shoes
- Nonweight bearing cast, since weight bearing impressions distort the metatarsal region (if not achieved, the other aspects have to do more work but it is possible)
“Balancing that gives the best metatarsal support and foot alignment”. Morton’s Neuroma is one of the most common problems that deserves great metatarsal support, and either pronatory or supinatory control. Previous blog posts have reviewed extensively the appropriate prescriptions for balancing, pronatory, or supinatory control. The best starting point is to take a suspension cast or scan. This will give you a good shape of the metatarsals which are flattened by semi- or full weight bearing imaging. When this is not accomplished, your orthosis will have to rely more heavily on non-exact metatarsal pads and off-loading pads which do work, but are not as scientific to me.
Our problem with obtaining good metatarsal support starts in the casting or digital imaging. Any impression of the skin in the metatarsal shaft area is never great at supporting the metatarsals due to the soft tissue overlying the skeletal structures. If you are great at contouring skin, balancing out deformities like any inverted or everted forefoot deformities, you still may not be able to really support the metatarsals as well as possible since there is so much soft tissue between the cast shape and bones. Plus, of course, the amount of soft tissue varies from patient to patient. Here we get our weakest pure support in a custom made functional foot orthosis, so we have to rely on metatarsal pads to push up softly through the soft tissue and get closer to the bones.
“Length of device ending at the surgical neck of the metatarsals” is a huge aspect of good metatarsal support. I see this problem all the time when orthoses are shortened for dress shoes due to shoe fit. Since this is reality for many patients, I have a discussion with them about having a second pair of orthotic devices shortened when we have to compromise our treatment for their shoe style. I won’t take the orthotic device that has normal length and shorten that one. This discussion is common after I have designed an orthosis that is working, and the patient is wondering what to wear in their dress shoes. The patient must know that the shorter orthosis is a compromise and that there may be more experimentation needed in the size of the metatarsal pads. Tight fitting dress shoes with neuroma care are a problem anyway since neuromas hate any tight compression. I try to convince patients to wear only dress shoes with removable foot beds until we can get the symptoms firmly under control.
“Intrinsic Metatarsal Arch 2-4, which will be part of our forefoot balancing” is an incredible help to designing a proper Morton’s Neuroma orthosis. Intrinsic Metatarsal Arch 2-4, which will be part of our forefoot balancing, I encourage anyone treating Morton’s Neuroma to get good at estimating the patient’s intrinsic metatarsal arch shape. Ideally, it is quite normal with a slightly plantarflexed first and 5th metatarsals to create a nice transverse metatarsal arch. If people want, I could describe the evaluation technique in a future post. So, after proper balancing of forefoot deformities, and evaluating the transverse metatarsal arch, having the lab place an intrinsic 2-4 metatarsal arch is an incredible help. It is foundational in why Root Based orthotic devices were/are the gold standard for any metatarsal problems.
“Adjustable Metatarsal Arch (top cover glued only to heel)” is something you learn from the patients all the time. When you choose one spot to place your met pads, you probably are going to be off 50% of the time. A met pad that is a 1 mm off right to left, or anterior to posterior, can be an irritant. Also, the thickness may be too much or too little. I find having the lab glue only the heel area of the top cover, allowing you and your patient to move the met pad around at office dispense visit works well.
“Metatarsal Support sulcus length 1st, 2nd and 5th as part of our off loading sore areas” is a great help in neuroma care. The general rule is if you off load the metatarsal head you have to support the metatarsal shaft. This prevents the metatarsal from dropping into the hole you have created making the foot deformity worse, or creating a foot deformity of a dropped metatarsal. Therefore, using supports under the metatarsal heads both medial and lateral to the sore area should be accompanied by metatarsal padding. They work marvelously together. Due to shoe constraints, dress orthoses tend to only have met pads, and athletic orthoses have both met pads and off loading supports.
“Metatarsal Bar” is a good concept to gently elevate the distal edge of the orthosis off the support surface. It is typically neutral and 1 mm thick, therefore not placing a varus or valgus influence. Some labs just leave the distal edge of the plastic full thickness instead of the traditional biveling to create this effect.
“Wide as possible for the shoe and the foot (dress orthotic devices normally 1 cm narrower than athletic)” is another variable that can help us. Increasing width implies increasing stability which we need, however increasing width adds more shoe tightness that can work against us. In general, working with athletic shoes or dress shoes with removable foot pads, I can make the orthosis as wide as the foot to really gain stability and metatarsal support. In dress shoes without removable foot beds, I must use the standard dress shoe width.
“Lower heel contact maximal” makes sure that when standing the pitch of the orthosis is not too angled forward.
“Nonweight bearing cast, since weight bearing impressions distort the metatarsal region (if not achieved, the other aspects have to do more work but it is possible)” has already been discussed. It is my preferred option for imaging at all times, but very important for neuroma care.
Next week, we will take all this information and design our ideal neuroma orthosis.
