Unraveling The Mystery Of Metatarsalgia Under The Second Metatarsal Head

Metatarsalgia under the second metatarsal head is a condition we treat on a daily basis. Unfortunately, it can be difficult to treat and manage. We are always looking for a reason why a condition occurs. Sure, it is easy to say, “It’s because you are wearing high heels” or “You have a high arch so all of your weight is on the ball of your foot,” or “It’s because you have a bunion and the first metatarsal bone isn’t weightbearing.” To that end, we examine the foot, watch the patient walk, check for hypermobility of the first ray and look at X-rays. We are trying to find a good explanation. Is it a long second metatarsal bone, a short first metatarsal bone, an abnormal first metatarsal (i.e. hallux valgus) or a high arch? I have been doing a lot of reading lately about Morton’s foot because I am putting a lecture together for the April Podiatry Institute meeting in Phoenix. There is a lot of information on the Internet about “Morton’s foot,” “Morton’s toe,” “Morton’s foot syndrome,” and “Morton’s foot type.” I have read Dr. Dudley Joy Morton’s works from the 1920s and he stated that “Dorsal elevation or a short first metatarsal causes an ineffective and non-functional weight bearing structure.”¹ Nowhere in his writings did Morton say anything about a “long second toe,” which at some point became known as the “Morton’s toe.” Morton felt that if the first metatarsal was shorter than the second, then that was the causation to excessive pressure on the second metatarsal. He was convinced that second metatarsal cortical hypertrophy noted on X-rays was due to this phenomenon. Three different published studies disproved this theory but I will save that for another blog. Morton also observed a short first metatarsal, hypermobility of the first ray and contracture of the gastrocnemius or Achilles with pes planus.¹ He also described interdigital neuromas with instability of the first metatarsal. This is confusing since Dudley Morton, MD, did not describe the Morton’s neuroma but Thomas George Morton, MD, named it in 1876.² To make things more confusing, today we often consider “Morton’s toe” synonymous with Morton’s neuroma or at least the main causation of it. When I was in residency, we did not spend much time on analyzing metatarsal length patterns. In my day, central metatarsal osteotomies were taboo unless we used them to address an iatrogenic deformity or a post-traumatic one. In the past 10 to 15 years, however, with the popularity and worldwide acceptance of Weil osteotomies, there is more emphasis on metatarsal length patterns in forefoot reconstruction, especially when there is a component of lesser metatarsalgia. I typically consider the metatarsal length pattern of 2>1=3>4>5 to be the norm (Bojsen-Moller described this in 1980).³ In 1995, Maestro recommended that if 1=2, the third metatarsal should be 4 mm less than the second, the fourth metatarsal is 6 mm less than the third and the fifth metatarsal is 12 mm less than the fourth.⁴ One can depict the Maestro line by drawing a line from the fibular sesamoid perpendicular to the second metatarsal to the fourth metatarsal head. In his book, Forefoot Reconstruction, Barouk also recommends and teaches this concept for reconstruction purposes.⁵ I do not know what the answer is but I guess that is what makes our profession challenging, exciting, frustrating and rewarding. It is hard to believe that each and every one of us will be trying to perfect foot surgery throughout our entire career of 30 to 40 years. I hate to be a pessimist but I don’t know if it will ever happen for me. I will keep trying though. Every time I think I am close, I have a case that falls apart on me. Foot surgery, and most notably reconstruction of the forefoot, can humble the most seasoned surgeons. References 1. Morton DJ. Metatarsus atavicus: the identification of a distinctive type of foot disorder. J Bone Joint Surg. 1927;9:531-44. 2. Morton TG. A peculiar and painful affection of the fourth metatarsophalangeal articulation. Am J Med Sci. 1876;71:31-45. 3. Bojsen-Møller F. Anatomy of the forefoot, normal and pathologic. Clin Orthop. 1980;142:10-18. 4. Maestro M, Augoyard M, Barouk LS, et al. Biomécaniques et repères radiologiques du sésamoïde lateral de l’hallux par rapport à la palette métatarsienne. Méd Chir Pied. 1995;11:145-154. 5. Barouk LS. Forefoot Reconstruction. Springer-Verlag, Paris, 2005, p. 220.