Free Health Essays - Functional hallux limitus is generally defined as a deformity of the first metatarsophalangeal joint that acts to restrict the range of movement
Functional hallux limitus is generally defined as a deformity of the first metatarsophalangeal joint that acts to restrict the range of movement of dorsiflexion during the propulsive phase of gait. (Chapman C.,1997)
Different authors refine this basic definition further, some adding a further qualification that it is defined by a reduction of the range of dorsiflexion to less than 65 degrees. (Camasta C A.,1996). If the range is reduced to less than 5 degrees then the term Hallux rigidus is generally applied and is a subdivision of the clinical spectrum of functional hallux limitus. For the sake of completeness we should record that the normal range is generally 65-75 degrees of dorsiflexion.
We should also define the difference between the structural and functional varieties of this condition. The functional variety of the condition is diagnosed only if the restriction in the range of movement is apparent during weightbearing (and by definition is not present during passive, non-weightbearing movement). The structural variety exhibits a restriction of movement in both eventualities. (Dananberg H J et al 1996),
The assessment and diagnosis of functional hallux limitus is made either on clinical examination and history or with the assistance of formal gait assessment. As far as the latter is concerned, it is manifest as a biomechanical disability that has the predisposition to result in a comparatively ineffective propulsive mechanism (of varying degrees of severity) during the toe-off phase of the gait cycle. It can be accompanied by forefoot metatarsalgia together with other abnormalities of gait pattern (Townley and Taranow, 1994)
The definition of a successful treatment is :
To eliminate pain, restore motion, and maintain the strength and stability of the great toe, but must also reconstitute the normal distribution of weightbearing stresses sustained by the transverse metatarsophalangeal arch of the forefoot. (Townley and Taranow, 1994, p.575).
Aetiology of the condition
This is, to some extent a matter of controversy, as there are thought to be a number of independent but not mutually exclusive theories on the issue. (Laing P.,1995). Many authorities agree that the basic pathology stems from first ray hypermobility which, in itself is secondary to abnormal pronation. (Jahss M.,1982)
In lay terms this means that the ray is moving when it should be stable. The fundamental issue here is one of abnormal pronation. During propulsion the subtalar joint is pronated and the midtarsal joint is mobile when it should be locked. This allows the first metatarsal to be hypermobile.. this results in the first metatarsal dorsiflexing when it should be plantarflexing. The less the ability of the first metatarsal to plantarflex, the less becomes the ability of the first metatarsophalangeal joint to move and the greater becomes the need for compensatory mechanisms to come into play.
How the condition affects the gait cycle
The restriction of flexion in the movement of the of the first metatarsophalangeal joint manifests itself in a number of ways that can be either directly attributable to the condition or also compensatory mechanisms that allow for normal propulsive gait to be accomplished.
At the most basic level, the condition affects the ability of the foot to move fully over the hallux when the forefoot is planted on the ground. The degrees of impairment are variable (right up to hallux rigidus) and tend to progress with both age and length of time that the condition has been present. (Root M L et al 1987),
Typical signs associated with functional hallux limitus can be pronation of the feet while standing and walking. They will have varying degrees of reduced propulsivity from their gait. They can have either an abductory twist during the gait cycle or can demonstrate an abnormally abducted angle of gait and associated delay in the heel off segment of the gait cycle. (Light M R.,1996)
The early stages of the condition (typically in the younger patient) can go unnoticed and undiagnosed but as the condition becomes more advanced and obvious, compensatory changes in the gait cycle can become more apparent and pronounced. Progressive hypopropulsion, varying degrees of pelvic tilt and rounded shoulders are the more progressive accompaniments of the severe condition as the body attempts to compensate for the mechanical disadvantage of the condition. (Dananberg. HJ 1993)
The use of orthoses for functional hallux limitus
Because we have presented evidence to suggest that the basic functional abnormality in functional hallux limitus is abnormal pronation, it follows that the function of a compensatory orthotic is to reduce the effect of this pronation and to limit and control the abnormal pronatory forces that are apparent during the gait cycle.
It should be noted that orthoses are not the only available modality of rational treatment as surgery and other interventions have a place, but we shall not consider these further.
The key to successful treatment appears to be the ability to keep the subtalar joint in its neutral position, particularly during the propulsive phase of the cycle. This allows the stabilisation (or locking) of the midtarsal joint and this should allow normal movement of the first metatarsal. It follows from this that there then should be a return to a normal range of movement (dorsiflexion) at the hallux and reduces the need for postural compensation in the gait cycle. (Banks, A.S et al 1987)
The main concept is to have the prescription orthoses induce an increase in the range of motion at the 1metatarsophalangeal joint by causing resupination of the foot from midstance through propulsion. (Sanner W H.,1994)
It is also of great importance, when considering the appropriate orthosis, to consider other factors further up the biomechanical train. Those influences that cause a varus tendency in the lower limb will serve to exacerbate the condition and therefore minimise the impact of the correctional orthosis. Conditions such as tibia varum and forefoot inversion are particularly relevant. The patient may also have a degree of rearfoot varus deformity which may require a greater degree of varus correction in the orthotic cast to allow for better foot-ankle-leg alignment in all phases of the gait cycle. The clinical judgement of the degree of correction (inverted balancing) is best done in the neutral calcaneal stance position (Petchell A et al 1998).
We should also note that the prescription of an orthotic alone is seldom sufficient treatment for the condition. One should always consider other measures which may help such as reducing the amount of high impact activities (such as running), the concurrent prescription of NSAIAs may help to reduce the inflammatory reaction in the periarticular structures that commonly accompanies the condition (Shereff and Baumhauer, 1998 (A)).
Other authorities (Holmes 1994) suggest that footwear modification to include a higher toebox to avoid first ray irritation. Other mechanical devices such as an inflexible steel base to the shoe will decrease joint activity and can be coupled with a rocker bottom sole which will help to promote forward body propulsion in the gait cycle. (Bouche, R.T et al 1996).
It should be noted that, while recording certain authority’s opinion relating to treatment there have been no reputable prospective trials which have assessed the actual efficacy of these options. (Shereff and Baumhauer 1998, (B))
References
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Hallux limitus and hallux rigidus. In
McGlamry, E.D., Banks, A.S. and Downey, M.S. (Ed) Comprehensive textbook of foot surgery (2nd ed).
Williams and Wilkins, Sydney. pp.608-616.
Bouche, R.T. and Adad, M.R. 1996.
Arthrodesis of the first metatarsophalangeal joint in active people.
Clinics in Podiatric Medicine and Surgery, 13, (3), pp. 461-484.
Camasta C A.,1996
Hallux Limitus and Hallux Rigidus.
Clinics in Podiatric Medicine and Surgery. 13(3) pp.423-445
Chapman C.,1997
Looking through JAPMA.
The Journal of British Podiatric Medicine. 52(8) pp113
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HJ. Dananberg. Gait style as an etiology to chronic postural pain. Part 1. functional Hallux Limitus
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Nonsurgical Treatment of Hallux Limitus.
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Hallux Rigidus. In Gould, J.S. (Ed.) Operative foot surgery.
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Disorders of the Foot Vol 1
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Petchell A.,Keenan AM.,Landorf K.,1998
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Clinical Methods for Predicting the Effectiveness of Functional Foot Orthoses. Clinics in Podiatric Medicine and Surgery. Vol 2, number 2.pp288-291
Shereff, M.J. and Baumhauer, J.F. 1998. (A)
Hallux rigidus and osteoarthrosis of the first
metatarsophalangeal joint.
The Journal of Bone and Joint Surgery, 80-A, (6), pp. 898-908.
Shereff, M.J. and Baumhauer, J.F. 1998. (B)
Hallux rigidus and osteoarthrosis of the first
metatarsophalangeal joint.
The Journal of Bone and Joint Surgery, 80-A, (6),
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Townley, C.O. and Taranow, W.S. 1994.
A metallic hemiarthroplasty resurfacing prosthesis for the hallux metatarsophalangeal joint.
Foot and Ankle International, 15, (10), pp. 575-580.
