Clin Orthop Surg.  2010 Mar;2(1):13-21. 10.4055/cios.2010.2.1.13.

Extraarticular Subtalar Arthrodesis for Pes Planovalgus: An Interim Result of 50 Feet in Patients with Spastic Diplegia

• Yoon HK
• Park KB
• Roh JY
• Park HW
• Chi HJ
• Kim HW

• KMID: 1110344
• DOI: http://doi.org/10.4055/cios.2010.2.1.13

Abstract

BACKGROUND: There are no reports of the pressure changes across the foot after extraarticular subtalar arthrodesis for a planovalgus foot deformity in cerebral palsy. This paper reviews our results of extraarticular subtalar arthrodesis using a cannulated screw and cancellous bone graft.
METHODS
Fifty planovalgus feet in 30 patients with spastic diplegia were included. The mean age at the time of surgery was 9 years, and the mean follow-up period was 3 years. The radiographic, gait, and dynamic foot pressure changes after surgery were investigated.
RESULTS
All patients showed union and no recurrence of the deformity. Correction of the abduction of the forefoot, subluxation of the talonavicular joint, and the hindfoot valgus was confirmed radiographically. However, the calcaneal pitch was not improved significantly after surgery. Peak dorsiflexion of the ankle during the stance phase was increased after surgery, and the peak plantarflexion at push off was decreased. The peak ankle plantar flexion moment and power were also decreased. Postoperative elevation of the medial longitudinal arch was expressed as a decreased relative vertical impulse of the medial midfoot and an increased relative vertical impulse (RVI) of the lateral midfoot. However, the lower than normal RVI of the 1st and 2nd metatarsal head after surgery suggested uncorrected forefoot supination. The anteroposterior and lateral paths of the center of pressure were improved postoperatively.
CONCLUSIONS
Our experience suggests that the index operation reliably corrects the hindfoot valgus in patients with spastic diplegia. Although the operation corrects the plantar flexion of the talus, it does not necessarily correct the plantarflexed calcaneus and forefoot supination. However, these findings are short-term and longer term observations will be needed.

Keyword

Pes planovalgus; Cerebral palsy; Subtalar joint; Arthrodesis; Extraarticular

MeSH Terms

Adolescent
Arthrodesis/*methods
Bone Screws
Bone Transplantation
Cerebral Palsy/*complications
Child
Child, Preschool
Female
Flatfoot/etiology/radiography/*surgery
Foot/radiography
Foot Deformities, Acquired/etiology/*surgery
Humans
Leg
Male
Muscle Spasticity/complications
Muscle, Skeletal/surgery
Postoperative Complications
Subtalar Joint/radiography/surgery
Walking/physiology

Figure

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  Fig. 1 Foot pressure was measured in 9 areas including the hallux, each metatarsal head, midfoot, and calcaneus. The white curved line represents the path of the center of pressure.

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  Fig. 2 The pressure-time curves of the foot. If the sole is divided into two regions, shaded areas a and b represent the pressure-time integral of each region. Summation of a and b equals the total impulses. Relative vertical impulse of each region was calculated as a pressure-time integral of that region divided by the total impulses

• 

  Fig. 3 The path of the center of pressure is represented as a curved white line, and a construction line is drawn from the first to the last center of the pressure data point. The length (a) represents anteroposterior length of the foot; the length (b) anteroposterior length of the path of the center of pressure; the length (c) the lateral deviation of the center of pressure from the construction; the length (d) the maximum width of the foot. Anteroposterior index of the path of the center of pressure (%) = (b / a) × 100. Center of pressure excursion index (%) = (c / d) × 100. The black arrow represents the initial medial deviation of the path of the center of pressure in a patient who underwent an extraarticular subtalar arthrodesis.

• 

  Fig. 4 Anteroposterior and lateral radiographs of the foot showing anteroposterior and lateral talocalcaneal angles. Before surgery (A), talonavicular subluxation and plantarflexion of talus was noted. At the final follow up (B), talonavicular subluxation was reduced and plantarflexion of the talus was corrected. However, calcaneal pitch was not corrected accordingly.

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  Fig. 5 Sagittal plane kinematic and kinetic changes in the ankle before and after surgery.

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  Fig. 6 Relative vertical impulse before and after surgery. MT: Metatarsal head, Lat M: Lateral midfoot, Med M: Medial midfoot, Lat C: Lateral calcaneus, Med C: Medial calcaneus.

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