Hallux Limitus is a condition causing inflammation and soreness of the big toe, accompanied by restriction of movement. If untreated, it can lead to a more severe position of complete rigidity. Fortunately, treatment options are simple and straightforward once we understand the underlying biomechanical processes taking place.
In this condition, the range of dorsiflexion available at the first metatarsophalangeal joint (MPJ) is decreased from normal. The amount of discomfort associated with a hallux limitus deformity can range from no pain at all to severe and disabling.
Normal first MPJ range of dorsiflexion motion is considered to be ~70 degrees. This is the maximim required amount of dorsiflexion of the hallux relative to the plantar aspect of the foot during the propulsive phase of the gait cycle. If there is less than 70 degrees of motion in both the non and weight bearing foot, a structural hallux limitus is present. If the limitation is present only in the weight bearing foot, then a functional hallux limitus is present. There are a variety of biomechanical etiologies of both types of hallux limitus. All of them work in the weight bearing foot during the propulsive phase of gait, to prevent normal dorsiflexion at the first MPJ.
This restriction of motion at a time when motion is absolutely necessary to ensure normal gait creates excessive internal compression forces within the dorsal half of the first MPJ. These are commonly referred to as “jamming” of the joint. The result is the classic symptom of dorsal first metatarsal head pain. Inflammation is created by the excessive bone against bone compression of the proximal phalanx abutting the first metatarsal head during propulsion.
Complex interactions take place between the dynamic internal joint torques, ligamentous and muscular tensions, and joint compression forces. They inhibit the first ray from plantarflexing during stance phase. From a clinic standpoint, simplify these interactions by thinking of only the ground reaction forces plantar to the first MPJ.
An increased amount of ground reaction force plantar to the first MPJ resists plantarflexion of the first ray. A decreased amount of ground reaction force plantar to the first MPJ lessens those forces of resistance. The main etiologies in the creation of hallux limitus all increase the ground reaction forces to the first MPJ. The two most common biomechanical causes of hallux limitus are excessive subtalar joint pronation and a relatively long first metatarsal. Both result in an increased amount of ground reaction force plantar to the first MPJ in late midstance and propulsion. This excessive ground reaction force tends to push up on the first metatarsal head, which in turn further resists normal first ray plantarflexion and therefore normal hallux dorsiflexion.
Treatment become simple once the biomechanical etiology of the hallux limitus is appreciated. Do what is necessary to reduce the ground reaction forces plantar to the first MPJ during late midstance and propulsion. Of course, to accomplish these goals, functional foot orthoses are the treatment of choice.
Treatment through Orthotic Modification
Here are specific modifications to use with the clinical presentation of hallux limitus:
- Balance the forefoot and use low to perpendicular intrinsic or extrinsic rearfoot posting.
- For hallux limitus, add a reverse morton’s forefoot extension to the sulcus to accommodate the first MPJ. We use 1/16″ Korex extending across the second to fifth met head. This allows the first MPJ to “float” so that the ground reaction forces are markedly decreased. For a functional hallux limitus, the pad extends across the width of the forefoot, with a cutout at the first MPJ.
- For a hallux limitus, we use a morton’s extension, in order to limit motion of the first MPJ.
- Use a relatively stuff orthosis plate along with a rearfoot post to achieve tighter control of excessive subtalar pronation.
Functional foot orthoses using these modifications almost always relieves dorsal joint pain that is caused by hallux limitus.. If the patient prefers a half length orthotic, adhere a piece of felt or thin padding to the insole of the shoe.