Most of us have heard of the benefits that custom foot orthotics can have to treat foot abnormalities, such as pronation, plantar fasciitis or ulcers, but have you ever heard of a Morton’s Neuroma?
Morton’s neuroma is a benign neuroma of an intermetatarsal plantar nerve. It is one of the less common foot ailments. Nonetheless, it can result in great frustration, both for the clinician seeking conservative solutions and for the client looking for relief. One of the recommended treatments is custom foot orthotics, which will have various success rates depending on the type of orthotic dispensed and the knowledge of the clinician. Without a thorough understanding of the relationship between the arches of the foot and their contribution to overall foot health, successful management of Morton’s neuroma may be compromised.
Morton’s Neuroma is most often blamed on poor footwear selection. However, a significant number of clients have no history of wearing inappropriate footwear. It may be time, therefore, to consider biomechanical influences as the likely cause of Morton’s neuroma.
The Medial Longitudinal Arch, the Lateral Longitudinal Arch and the Transverse, or Metatarsal Arch all work interdependently to form a plantar “vault.” This architectural design optimizes strength yet permits sufficient flexibility to accommodate changes in terrain.
When the Medial Longitudinal arch becomes too elongated or stays elongated for too long (excess or prolonged pronation), the forefoot abducts and becomes unstable. Abduction causes the forefoot to stray laterally into the side of the shoe, giving the impression that the shoe width is no longer appropriate. Over-pronation also “unlocks” the first metatarsal ray. It becomes hypermobile during push-off, allowing it to move upward when ground forces are applied and thus transferring some of the push-off force to the lesser rays. This excess workload on the lesser rays results in increased compression of the interdigital spaces.
The integrity of the Metatarsal Arch is important for the alignment of the metatarsal heads relative to each other. A laxity in the ligament structure maintaining this arch could result in plantar flexed rays and/or a widening of the ball of the foot as the metatarsal rays splay outward. This again gives the impression that the footwear is causing compression across the toe box.
Success in prescribing custom foot orthotics can be optimized by ensuring your orthotic provider fully understands the biomechanics of the feet and is able to provide a product that can effectively control overpronation while integrating sufficient metatarsal support to lift and separate the joint space irritating the neuroma.