The effects of medial and lateral displacement calcaneal osteotomies on ankle and subtalar joint pressure distribution.

We compared the pressure distribution in the ankle and posterior facet of the subtalar joint following 1 cm medial and lateral displacement calcaneal osteotomies to the pressure distribution in the intact foot. Six cadaver specimens were loaded in neutral alignment while pressure measurements were recorded. A 1-cm medial displacement osteotomy shifted the average center of force in the ankle 1.0 mm medially (p = 0.36) while a lateral displacement osteotomy shifted the center of force 1.1 mm laterally (p = 0.42). There was also a slight shift in the percentage of pressure toward the side of the talus to which the calcaneus was shifted. For the lateral displacement osteotomy, the pressure increased 4.0% in the lateral-most quadrant (p = 0.05), while the medial osteotomy increased the pressure 1.3% in the medial quadrant (p = 0.30). In the subtalar joint, a medial displacement osteotomy shifted the pressure distribution slightly medially (5.9%, p = 0.06) and more anteriorly (9.6%, p = 0.02) while the distribution was shifted laterally (5.9%, p = 0.17) and anteriorly (5.6%, p = 0.03) with a lateral displacement osteotomy. These shifts of percentage of pressure between quadrants of the joints were slight-less than 5% in the ankle and less than 10% in the subtalar joint. Significant translation of the calcaneal tuberosity appears to have only a small effect on pressure distribution in the ankle and posterior facet of the subtalar joint in a weighted cadaver model.

Plantar pressure and radiographic changes after distal calcaneal lengthening in children and adolescents.

Eleven feet (nine patients) with symptomatic flatfoot deformities of various etiologies that had failed nonoperative treatment underwent distal calcaneal lengthenings. Pre- and postoperative plantar pressure measurements and radiographic parameters were compared and a postoperative clinical evaluation was performed using the AOFAS ankle and hindfoot scoring system. Follow-up ranged from 4 to 20 months (mean, 11.1 months). Plantar pressure parameters including contact area, mean, and peak pressures indicated significant lateral shifts in the weight-bearing surface of the foot. The most significant radiographic changes were an improvement in the talonavicular coverage angle (mean, 17.3 degrees) on the anteroposterior view and an improvement in the talo-first metatarsal angle (16.2 degrees) on the lateral view. The average postoperative American Orthopedic Foot and Ankle Society score was 90 with seven excellent, three good, and one poor results.

Stress fracture of the fifth metatarsal after Evans' calcaneal osteotomy: a report of two cases.

The Evans calcaneal lengthening osteotomy has gained popularity in recent years for the treatment of symptomatic flexible pes planus deformity. To our knowledge, the occurrence of a stress fracture of the fifth metatarsal has not been reported after this procedure. We report two such cases and discuss the probable mechanism of this problem, a relative overloading of the lateral aspect of the foot. Both cases were treated successfully with immobilization. Clinicians should be aware of this possible problem and treat it appropriately.

Surgical release of tethered spinal cord: survivorship analysis and orthopedic outcome.

Between January 1988 and February 1995, 133 tethered spinal cord-release procedures in 88 consecutive patients were performed at our institution and were used to determine survivorship data for surgical release of tethered spinal cord. The diagnoses included spinal dysraphism (67), achondroplasia (nine), isolated tethered cord (nine), cerebral palsy (three), and others (seven). Survivorship data were calculated for the initial and first-revision tethered cord release. There was a 50% revision rate by 5 years after initial tethered-cord release and a 57% revision rate by 2 years after a second release. Thirty-six patients were excluded for having <2 years of clinical follow-up, leaving 97 spinal cord releases in 52 patients available for outcome analysis. At a mean follow-up of 4.4 years (range, 2-11.3), 58% of patients required one or more orthopedic procedures after tethered-cord release. The average number of orthopedic procedures per year before release (0.28/year) was found to increase after initial release (0.39/year; p < 0.05). These data demonstrate the frequent need for operative revision after index tethered-cord release, especially in children with spinal dysraphism. In addition, the need for orthopedic procedures after tethered spinal-cord release frequently persists.