Pertinent Pearls On Custom Orthoses And Modifications

Author(s): 
Clinical Editor: Nicholas Romansky, DPM

These expert panelists explore the efficacy of orthoses for hallux limitus, the impact of orthotic devices on the kinetic chain and key considerations with topcovers.

Q:

How do you use orthotics for hallux limitus?

A:

David Levine, DPM, CPed, notes hallux limitus can be a challenging problem to treat conservatively and surgically. He says it is helpful to distribute the pressure more evenly across the forefoot.

   In some instances of hallux limitus, it is also key to reduce the forces going through the first ray and Dr. Levine says one can accomplish this in several ways depending upon the foot type. He notes some patients respond to a cutout for the first ray, which can allow relative plantarflexion, and some patients respond to a Morton’s extension. R. Paul Jordan, DPM, also notes the efficacy of a cutout under the first metatarsal head. He says this orthosis shell modification offers an adequate contour for the first metatarsal to plantarflex, which permits relative, passive hallux dorsiflexion at the first metatarsophalangeal joint (MPJ) in the terminal stance phase of gait.

   Furthermore, Dr. Levine notes some patients require limited pronation in the terminal portion of midstance in order to prevent dorsiflexion and jamming of the first ray. Likewise, for Kevin Kirby, DPM, the goal of orthosis therapy is to reduce the dorsiflexion of the first ray in patients with functional or structural hallux limitus, who have a restriction in dorsiflexion of the hallux but no pain at the end of hallux dorsiflexion range of motion. Reducing dorsiflexion of the first ray lessens the tensile force within the medial band of the plantar fascia during late midstance and propulsion, according to Dr. Kirby. If one can reduce the tension within the medial band of the plantar fascia with a foot orthosis, he says this will decrease first MPJ compression forces.

   Dr. Kirby also says that by designing the orthosis to allow more normal hallux dorsiflexion during propulsion, this will allow the re-establishment of more normal gait function in the patient. To accomplish this, he suggests designing the orthosis to reduce pronation motion of the foot by using a medial heel skive and tightly fitting medial longitudinal arch. By using a reverse Morton’s extension, Dr. Kirby says one can design the device to reduce the ground reaction force plantar to the first metatarsal head.

   However, if the patient has a structural hallux limitus or hallux rigidus, and the patient reports pain within the joint at the end of hallux dorsiflexion range of motion during the non-weightbearing examination, Dr. Kirby advocates including a Morton’s extension instead. As he explains, the Morton’s extension, by dorsiflexing the first ray, will reduce hallux dorsiflexion, eliminate the painful end range of dorsiflexion motion and make propulsion less painful during walking gait.

   Although he does not see patients with hallux limitus in his pediatric practice, Dr. Jordan treats a significant number of children with a functional hallux limitus. He notes the symptoms are rarely localized in the great toe or even the foot when pediatric functional hallux limitus is a component of the child’s pedal pathomechanics. Most often, the functional limitation affects proximal structures in a compensatory reaction to the limited motion at the first MPJ, which he notes poses an obstacle to an efficient or fluid terminal stance phase of gait.

   Since there are many biomechanical strategies that one can use, Dr. Levine notes the most important factors are the patient history and the biomechanical exam.

   “Often other variables will present and if they are addressed properly, the chance of favorable results with conservative care will increase,” notes Dr. Levine.

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