I like things that are practical, things that I can take back to my practice and start using right away. I think Morton’s neuromas are underdiagnosed and therefore undertreated. The typical complaint of burning or numbness in the ball of the foot is a relatively easy diagnosis, but neuromas can also cause referred pain.
I tend to see a lot of neuromas in conjunction with heel pain. The heel pain is often the dominant symptom. Once it is resolved, the neuroma pain often becomes more evident. I often see the symptom of intolerance to orthotics being used to treat heel pain. The complaint of vague discomfort with orthotics is often something that will clue me in to the neuroma.
Once I am suspicious of a neuroma, I like to confirm the diagnosis with a diagnostic steroid injection. I like to get feedback initially from the patient after injection. If the pain is gone or improved, this confirms the diagnosis to me.
I then have the patient track the injection over the next week daily with a diary. I ask the patient to bring the dairy back for me to check the following week. I typically see one of three responses. The pain may be relieved for only a few hours, a few days or for the entire week.
If the pain is better for the entire week, I like to follow up the injection with a round of oral steroids. If the pain relief is only temporary, then I recommend starting sclerosing injections. I use a 4% solution and give a 0.5cc injection every two weeks. I do a minimum of five injections. If the patient still has subjective complaints or objective findings, then I will do a sixth or seventh injection.
I do think it is important to follow up on the injections or steroids with custom orthoses. In my mind, there is usually a biomechanical etiology to this condition so custom orthoses make sense to me once the original symptoms are under control. This is important. I make sure that the symptoms are resolved prior to orthotic use. I have anecdotally noted that neuromas respond about 85 percent of the time to this type of therapy.
If a patient is non-responsive to this therapy, then I recommend a neurectomy. Decompression does not make any sense to me because if you catch the nerve in the swelling stage, it should respond to steroids. Those that do not have typically undergone fibrotic changes and the nerve is permanently damaged. How then is decompression going to help? I do not believe that it does. I still feel if a surgical procedure is necessary, then a neurectomy is the procedure of choice.
Why I Prefer The Plantar Approach For Neurectomy
I prefer the plantar approach for neurectomy. I choose this for two primary reasons. The first reason is that by using the plantar approach, one can sever the nerve well behind the weightbearing surface. This helps to lessen the incidence of a stump neuroma. I believe the dorsal approach only allows one to cut the nerve just at the proximal metatarsal head level, which is still in a weightbearing region.
Secondly, the plantar approach prevents the need to release the deep transverse metatarsal ligament. It has been documented that this does heal back together but what about the destablization this creates until that occurs or the fact that the ligament more than likely heals in a lengthened state? The plantar approach eliminates the need to cut this ligament. The plantar approach also allows a much more precise resection of the nerve without damage to any of the other structures in the area.
I think one of the main reasons many are reluctant to use the plantar approach is because of unfamiliarity. One pearl for this approach is if you cannot find the nerve, you are probably too deep. It is usually within the fat either medially or laterally. I like to identify the proper digital branches and then free the nerve as far proximally as possible. I then resect the nerve under tension as far proximal as possible.
I use simple interrupted sutures to close. I find this leaves the best scar in comparison to horizontal mattress sutures. I allow the patient to be fully weightbearing in a walking boot for three weeks and leave the sutures in for three weeks as well.
The main complication that I see with a plantar incision is some callusing along the incision site, which I just trim a few times and usually it will resolve. Scar tissue is common with the plantar approach. I have the patients massage the incision line to help break it up. Patients tend to do very well with this approach and the numbness associated with the procedure is of little issue to the patient.
I hope this practical approach to Morton’s neuroma is beneficial to you.