Synonym: claw foot
Pes cavus is a deformity of the foot which has a very high arch and is relatively stiff. This deformity does not flatten on weight-bearing.
A high arch with a medially angulated heel is called pes cavovarus. When this is complicated by foot drop and equinus of the ankle, this is called pes equinocavovarus.
In cases where the primary deformity is excessive ankle and hindfoot dorsiflexion, it is called pes calcaneovarus.
This condition is caused by an imbalance between the agonist and antagonist muscles in the foot. There is often family history and it is usually bilateral. One in five cases are idiopathic.
- Progressive neurological disorders:
- Static neurological disorders:
Patients often complain of pain, instability, difficulty walking or running and also problems with footwear.
There is often a range of other foot deformities also present - eg, claw toes, increased calcaneal angle, 'cocked-up' big toe.
These vary with degree of deformity:
- Pain in the side of the foot and the metatarsals.
- Calluses on the plantar aspect of the foot.
- Instability of the ankle.
Neuropathies may be accompanied by neuropathic pain. With progression, deformity and rigidity become more severe. This can lead to overload of the lateral side of the foot and even to stress fractures of the fifth metatarsal.
Peroneal tendinopathy, Achilles tendon disorders, plantar fasciitis and ankle impingment are more common.
NB: a spinal tumour should be suspected in any patient with new unilateral presentation, without previous trauma.
- Foot shape is best observed when the patient is standing.
- Inspect shoes for signs of abnormal wear.
- Observe gait for varus or foot drop.
- Passive movements should be assessed to look for any joint contractures.
- Perform neurological examination for a possible underlying cause.
Take a full family history. It is very important to establish whether there is an underlying neurological diagnosis and whether this is progressive or static. Neurological symptoms, such as sensory changes, weakness and clumsiness may be present. Back pain or headaches may signify a central cause.
- X-ray of foot (weight-bearing).
- MRI scan of the spine if a tumour is suspected.
- Electromyography and nerve conduction tests may be indicated for some patients.
The management of pes cavus depends on the aetiology, rapidity of progression and also the severity of the symptoms. The risk of progression during childhood can be reduced by appropriate conservative treatment.
- Non-surgical treatment should be instituted early by orthotists and podiatrists.
- Physiotherapy to loosen tight muscles and improve strength of weak ones.
- Padding and orthotic shoes.
- Splints or appliances may be necessary for some patients.
- A caliper may be given to patients with very severe deformity and refractory ankle instability.
- Botulinum toxin type A injections into the peroneus longus and tibialis posterior have been trialled in patients with CMT, without success.
- Surgery is usually only justified when deformity is so pronounced or progressive that symptoms are intrusive and unresponsive to conservative treatments.
- The aims of surgery are to:
- Correct deformity.
- Relieve pain and preserve joint motion if possible.
- Re-balance muscle forces to aid gait and prevent progression of deformity.
- Depending on the nature of the deformity, procedures can be release of plantar fascia, tendon transfer, osteotomy and arthrodesis.
- Many patients need several operations.
Further reading and references
; Advances in Clinical Neuroscience and Rehabilitation (ACNR)
; Midfoot and forefoot issues cavovarus foot: assessment and treatment issues. Foot Ankle Clin. 2008 Jun13(2):229-41, vi. doi: 10.1016/j.fcl.2008.02.007.
; Cavus foot, from neonates to adolescents. Orthop Traumatol Surg Res. 2012 Nov98(7):813-28. doi: 10.1016/j.otsr.2012.09.003. Epub 2012 Oct 23.
; Overview of foot deformity management in children with cerebral palsy. J Child Orthop. 2013 Nov7(5):373-377. Epub 2013 Sep 14.
; Randomized trial of botulinum toxin to prevent pes cavus progression in pediatric Charcot-Marie-Tooth disease type 1A. Muscle Nerve. 2010 Aug42(2):262-7. doi: 10.1002/mus.21685.
; Medium to long-term follow-up following correction of pes cavus deformity. J Foot Ankle Surg. 2008 Nov-Dec47(6):527-32. doi: 10.1053/j.jfas.2008.06.007.
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