Can Foot Orthotics Relieve The Pain Of Hallux Rigidus?

I am always interested in theories and advice my colleagues post on the Internet regarding the use of custom foot orthoses to treat common pathologies. It is amazing to see the divergence of opinion regarding selection of materials, casting technique and prescription criteria to treat any single condition. Leading the list of pathologies that has the least agreement for orthotic therapy is hallux rigidus.

The term hallux rigidus is subject to misunderstanding. Many confuse hallux rigidus with hallux limitus. In 1887, Cotterill proposed the term hallux rigidus, referring to a degenerative arthritic condition of the first metatarsophalangeal joint (MPJ).1 This condition is characterized by objective findings of both painful and restricted range of motion of the first MPJ as well as characteristic radiographic findings of osteophyte formation, joint space narrowing and subchondral sclerosis.

Hallux limitus is a poorly understood podiatric term. The term “functional hallux limitus,” which Laird originally described, refers to a functional pathology in the first MPJ where there is normal range of motion in the off-weightbearing exam but a suspected restriction of range of motion during dynamic gait.2 This functional loss of extension of the first MPJ is theoretically responsible for symptoms elsewhere in the foot or leg, not in the great toe itself.3,4

Several of my colleagues have recommended orthotic modifications that are intended to improve range of motion of the first MPJ. These include a first ray cutout, a reverse Morton’s extension, a Kinetic Wedge® or a Cluffy Wedge® (Cluffy Institute).3-5

Hallux rigidus is a common foot disorder and ranks second to hallux valgus in terms of the frequency of disorders of the first MPJ.6 Since surgical procedures have yet to provide predictable and satisfactory outcomes for all stages of hallux rigidus, practitioners may recommend non-surgical options for their patients. Here is where the confusion and misunderstanding begins, particularly when it comes to prescribing functional foot orthoses to relieve the pain of hallux rigidus.

Clarifying Our Treatment Goals

The number one pitfall I see when reviewing orthotic recommendations for hallux rigidus is the confusion of treating functional hallux limitus versus an arthritic condition of the first MPJ (hallux rigidus).

When treating functional hallux limitus, we have the following goals:
• improve stiffness (or reduce hypermobility) of the first ray;
• improve stability of the hindfoot and midtarsal joint in order to facilitate optimal muscular action of the peroneus longus; and
• facilitate engagement of the windlass mechanism with increased dorsiflexion or extension of the hallux on the first metatarsal head.

All of these measures are geared to treating the symptoms of functional hallux limitus. These symptoms include lesser MPJ metatarsalgia and other postural complaints in the lower extremity. They do not include arthritic pain of the first MPJ.

When it comes to hallux rigidus, the symptoms arise from degenerative arthritis, which results from jamming of the hallux against the dorsal surface of the first metatarsal head. The patient will already have mechanically restricted range of motion of the first MPJ and loss of cartilage, usually on the dorsal half of the first metatarsal head. The symptoms are primarily isolated to the great toe joint.

Therefore, the goal of orthotic therapy for functional hallux limitus is to improve range of motion of the first MPJ. The goal of treatment for hallux rigidus is to restrict range of motion of the first MPJ. Even better, the goal should be offloading of the first MPJ.

When orthopedists try to “offload” an arthritic knee, they prescribe a brace that will provide a valgus torque and decompress the medial knee compartment. They do not prescribe an orthotic that will increase range of motion of the arthritic joint. They certainly do not intend to increase motion across the area of the joint where cartilage has eroded.

Why would anyone prescribe a first ray cutout, a Kinetic Wedge or a Cluffy Wedge (all designed to increase extension of the hallux on the first metatarsal head) for the treatment of hallux rigidus where the dorsal surface of the first metatarsal head has eroded?

These are excellent orthotic modifications available to improve plantarflexion of the first ray or extension of the hallux at the first MPJ. However, these additions will only exacerbate the symptoms of hallux rigidus by jamming the hallux dorsally on the arthritic portion of the first metatarsal head.

Re-Examining Our Approach To Conservative Therapy For Hallux Rigidus

A proper foot orthotic should either restrict range of motion of the first MPJ using a plastic foot plate extension under the hallux or have a design that encourages plantarflexion of the hallux. We can accomplish this by elevating the first metatarsal with a forefoot varus post. This may sound totally contrary to your current thinking about treating first MPJ pathology but it makes perfect sense when relating to offloading strategies for the knee.

Another strategy, with which I have had better success, is recruiting activation of the flexor hallucis longus and brevis to encourage plantarflexion of the hallux at the first MPJ. Patients with hallux rigidus have less pain running than walking. This is due to the muscular activation of the toe flexors during running, which limits extension of the digits.7 We can encourage activation of the toe flexors by instituting an exercise program similar to what we do for plantar heel pain syndrome.

By instituting exercises or using a Thera-Band (Hygenic Corp.) to resist concentric and eccentric contraction of the great toe flexors, we can improve plantarflexion of the great toe, reduce dorsiflexion and accordingly reduce the pain of compression in hallux rigidus.

I have found that a Morton’s extension will actually improve purchase of the great toe. This is brought about by active contraction of the flexor hallucis longus and brevis tendons. Activation of these tendons will reduce dorsal excursion of the hallux and prevent jamming against the arthritic portion of the first metatarsal head. The Morton’s extension does not actually elevate or extend the hallux to any significant degree, but does seem to provide a fulcrum for hallux flexion against the ground.

This advice is of course based upon personal observation but still has some foundation in basic biomechanics. I look forward to any feedback and discussion.

References
1. Cotterill J. Stiffness of the great toe in adolescents. Br Med J. 1887; 1(1378):1158.
2. Laird PO. Functional hallux limitus. Illinois Podiatrists. 1972; 9:4.
3. Dananberg HJ. Functional hallux limitus and its relationship to gait efficiency. J Am Podiatr Med Assoc. 1986; 76(11):648-52.
4. Clough J. Functional hallux limitus and lesser metatarsal overload. J Am Podiatr Med Assoc. 2005; 95(6):593-601.
5. Scherer PR. Functional hallux limitus and hallux valgus. In: Scherer PR (ed.), Recent Advances in Orthotic Therapy. Lower Extremity Review, Albany, N.Y., 2011, pp. 57-67.
6. Coughlin M. Arthritides. In: MJ Coughlin, RA Mann (eds) Surgery of the Foot and Ankle, 7th ed, Mosby, St. Louis, 1999, pp. 605–650.
7. Sasaki K, Neptune R. Differences in muscle function during walking and running at the same speed. J Biomech. 2006; 39(11):2005-2013.