Pes cavus

Principal authors: Louise Crawford, Jim Barrie

Latest evidence check March 2010

Plantar release

Traditionally soft tissue and tendon procedures were used to prevent deformity or for early supple deformities. Many currently used techniques combine these procedures.  Soft tissue procedures are primarily directed at release or resection of the plantar fascia and short toe flexors, on the basis that the deforming force of a contracted plantar fascia leads to a narrow arch base, plantarflexed 1st MT and heel pulled into varus by the windlass effect.

However, if the plantar fascial tightness is due to dorsiflexed MTP joints as part of the intrinsic-minus posture, correction might be more effective and less destructive if the toes and their plantar fascial connections were corrected first. This postulate of Stainsby's remains to be tested. 

Steindler (1921) advocated the procedure of plantar fascial release. He emphasised the importance of stripping the origins of short toe flexors and abductors of the great and little toes from the os calcis. Serial casting follows this procedure to help retain the correction. Sherman (1981) was an advocate of the procedure but advised against it in calcaneocavus deformity because, in the absence of a functioning triceps surae, the addition of a plantar release destabilises the os calcis. For calcaneal deformity, combination of plantar fascia release with calcaneal osteotomy would be appropriate. Soft tissue procedures alone have been used in children. Paulos (1980) reported good results in 26 of 27 feet with average 2.5 years follow up. They used plantar release in all patients with extensor transfer, Achilles lengthening, posterior release and/or tibialis anterior transfer as needed.

Gastrocnemius/Achilles lengthening

Gastrocnemius/soleus tightness or contracture can be addressed by lengthening the gastrocnemuis or Achilles tendon, or both. However, the extent of hindfoot equinus can be overestimated. From this study which shows that the hindfoot is in dorsiflexion, thus Achilles lengthening is contraindicated in most CMT patients and will only reduce the power of triceps surae in stance phase, have adverse effect on gait and worsen the deformity by causing increasing dorsiflexion.

Heel cord lengthening should only be performed if true equinus can be proven on radiographic analysis. Aktas and Sussman (2000) found that in a population of patients with Charcot-Marie-Tooth disease the hindffot was in dorsiflexion. Thus Achilles lengthening is contraindicated in most CMT patients and will only reduce the power of triceps surae in stance phase, have adverse effect on gait and worsen the deformity by causing increasing dorsiflexion. Heel cord lengthening should only be performed if true equinus can be proven on standing lateral radiographs.

Tendon transfers

Tendon transfers for cavus deformity follow the same principles as any other tendon transfer. Transferred tendons lose one strength grade and a muscle should only be transferred when it has a power grade of at least 4. They should be routed in as straight a line of pull as possible and secured to bone rather than tendon. Tendon transfer should not be performed until any fixed deformities have been corrected.

The Girdlestone-Taylor tendon transfer may be used for flexible lesser toe deformities without midfoot deformity. For those with midfoot deformity, the toe deformity may resolve spontaneously with midfoot correction.

Fixed and flexible clawing of the first metatarsal can be corrected by the Jones procedure and its modifications.  Jones popularised the procedure of correcting a flexible plantarflexed first ray by performing a plantar fascia release and long extensor (EHL) transfer to the first metatarsal neck. This removes the deforming effect of the EHL tendon on the MTPJ and counteracts the windlass effect on the medial arch by helping to dorsiflex the first metatarsal. The IP joint is fused (in adults) or tenodesed (in children) to prevent unopposed action of FHL. To this may be added a closing wedge osteotomy of the 1st metatarsal to become the ‘extended’ Jones procedure. This should be performed where there is a proximally rigid plantarflexed first ray.

Tynan and Klenerman (1994) reported good relief of clawing in 24 patients, although less than half had relief of pain under the first metatarsal head. Breusch (2000) obtained clinically satisfactory results in 74/81 adult patients who had a modified Jones procedure, although half of these had some reservations about the result. the commones cause of reservations was limited hallux MTP movement, in some cares with degenerative changes. This was commonest in patients who also had a peroneus longus to brevis transfer. Most of Breusch's patients also had a first metatarsal dorsiflexion osteotomy.

An alternative transfer for clawing of the hallux is to detach the FHL from its insertion and pass it through the proximal phalanx. Steensma (2006) reported six procedures for clawing, with good maintenance of alignment and relief of pain at 2 years.

In calcaneocavus, the gastrocnemius/soleus complex is weak and the tibailis anterior overacting. After bony correction or stabilisation the tibailis anterior and, if necessary, other motors, are transferred into the heel. Bradley and Coleman (1981) obtained improvement in gait and push-off in 19 feet, with improved foot shape in 16 and one over-correction. However, none had normal gait.