When Will We Start Calling Morton’s Neuroma What It Is: Morton’s Entrapment?

Stephen Barrett DPM FACFAS

In the December 2011 issue of Foot and Ankle Specialist, there is an interesting article titled “Long-Term Results of Neurectomy in the Treatment of Morton’s Neuroma: More Than 10 Years’ Follow-Up.”1

What is interesting about this article? There are several things really. First, in an inset sidebar on the first page of the article, it says: “… the cause of Morton’s neuroma remains unclear, and its etiology and treatment remain matters of controversy.”

Really? As they say on ESPN: “C’mon, man!” How can it be that now, in 2012, with everything we know, that “the cause of Morton’s neuroma remains unclear”?

We clearly know what causes Morton’s neuroma (I always try to refer to it as an entrapment except when needed for this type of example). It is a nerve entrapment, pure and simple.2-7 This is not difficult conceptually at all. If you don’t believe me, then read some of the referenced studies below.

A Closer Look At The Study Results

Let us get back to the report by Lee and colleagues on 19 patients who had a neurectomy between 1997 and 1999.1 There was a loss to follow up for six patients during the course of time so the report deals with 13 patients. Interestingly, the report cites six co-authors: Kyung Tai Lee, MD, Jun Beom Kim, MD, Ki Won Young, MD, Young Uk Park, MD, Jin Su Kim, MD, and Hyuk Jegal, MD.

What did they report? “Eight of the 13 patients scored more than 90 on the AOFAS scoring system, with 4 patients scoring 100 (Maximum score.) The average preoperative AOFAS forefoot score was 55.6+- 10.2 (range 42-72), whereas the average postoperative AOFAS forefoot score was 89.1+- (range 72-100; Table 1). Although this indicated an improvement, there was no statistically significant difference (P=.538).”

So if you are a “stats” surgeon, this means that you are better not operating on them at all if you take out the nerve. I know all the members of the nerve community out there will love that one. What if you’re not a “stats” surgeon and you just want to take care of people who have forefoot pain. What does it mean? Four of their patients got a 100 but five of their patients rated their result as with “major reservation” when rating their results. The lights on the Vegas Strip will go dim with these types of odds.

They did do a couple of cool things though. They measured the size of the beasts and found out that size didn’t matter and they gave us a table that shows the reported results of neurectomy in Morton’s “neuromas.” The best is 85 percent good outcomes and the worst is 51 percent, which is from the Womack study, which I recommend all to peruse.8

What these numbers, even the most successful, don’t show is that you enter a very dark and dirty arena when you go from the land of decompression to the dumpster fire of nerve resection. After having the privilege of working in a tertiary nerve clinic, where we saw, on average, eight patients a month whose lives had been virtually destroyed because there was a creation of a recurrent Morton’s neuroma (that is correct nomenclature — if you cut them out, you will get your neuroma), I can say that both “stats” surgeons and “non-stats” surgeons should be very wary of cutting or injuring an unharmed but only pinched nerve.

What will it take for the universe of foot surgeons to finally accept that “Morton’s neuroma” is really Morton’s entrapment? The American College of Foot and Ankle Surgeons now acknowledge this condition of “unclear etiology” as a compression neuropathy in their 2009 guidelines.9 Truthfully, maybe it should be named after our Italian friend and anatomist Civinini. Or how about Hauser or Hueter? I’d even go for Iselin if we just put entrapment behind their damn names. What if all the peer reviewers just say no from now on to the word “neuroma” once and for all, unless it really is one?

In Conclusion

After spending the last decade focused on peripheral nerve pathology and having many late night séances with the nerve gods, there have been some emerging truths with indelible clearness. Drink the alcohol and don’t inject it. Decompress it and don’t injure it. If you fail to follow these two simple “truths,” sometimes the burning never stops.

Additionally, I want to thank all of you who are sending in plantar fascia data for the world’s largest study on heel pain. Many thanks to those of you without plantar “fasciapathy,” who have submitted data. Your data is important and we still welcome anyone else to join. You can go to: http://www.surveygizmo.com/s3/700292/bd3b26d9e831 and print out the data sheet and instructions.

References

1. Lee KT, Kim JB, Young KW, Park YU, Kim JS, Jegal H. Long-term results of neurectomy in the treatment of Morton’s neuroma: more than 10 years’ follow-up. Foot Ankle Spec. 2011; 4(6):349-53.

2. Alexander IJ, Johnson KA, Parr JW. Morton's neuroma: a review of recent concepts. Orthopedics. 1987; 10(1):103-106.

3. Diebold PF, Delagoutte JP. [True neurolysis in the treatment of Morton's neuroma]. Acta Orthop Belg. 1989; 55(3):467-471.

4. Gauthier G. Thomas Morton's disease: a nerve entrapment syndrome. A new surgical technique. Clin Orthop Relat Res. 1979; 142:90-92.

5. Graham CE, Graham DM. Morton's neuroma: a microscopic evaluation. Foot Ankle. 1984; 5(3):150-153.

6. Nemoto K, Mikasa M, Tazaki K, Mori Y. Neurolysis as a surgical procedure for Morton's neuroma. Nippon Seikeigeka Gakkai Zasshi. 1989; 63(5):470-474.

7. Dellon AL. Treatment of Morton's neuroma as a nerve compression. The role for neurolysis. J Am Podiatr Med Assoc. 1992; 82(8):399-402.

8. Womack JW, Richardson DR, Murphy GA, Richardson EG, Ishikawa SN. Long-term evaluation of interdigital neuroma treated by surgical excision. Foot Ankle Int. 2008; 29(6):574-577.

9. Thomas JL, Blitch EL, Chaney DM, Dinucci KA, Eickmeier K, Rubin LG, Stapp MD, Vanore JV. Diagnosis and treatment of forefoot disorders. Section 3. Morton's intermetatarsal neuroma. J Foot Ankle Surg. 2009; 48(2):251-256.

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