SKEWFOOT IN CHILD WITH UNDIAGNOSED SKELETAL DYSPLASIA

Scott Norris, D.O., Orthopaedic Resident

Dan Mason , M.D., Attending Pediatric Orthopaedic Surgeon

Sept. 19, 1995

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

CASE HISTORY:

This is a 6 year old white male, with an undiagnosed skeletal dysplasia, who has been followed for 5.5 yrs. Previous surgery includes bilateral femoral and tibial osteotomies for bilateral valgus deformities with good results. His foot deformity has never been treated with with casts or splints, but has worn AFO braces for persistent valgus hind foot deformities. Present exam reveals the following bilateral foot deformities.

1. hindfoot valgus of approx. 20-30 degrees
2. metatarsus adductus
3. prominence of the talar head in the medial arch with thickened callus over the bony prominence

Radiographs reveal the following deformities:

1. hindfoot valgus with AP talocalcaneal angle of > 35 degrees
2. lateral subluxation/dislocation of the navicular from the talar head
3. adduction of the metatarsals with the talus- 1st metatarsal angle to be divergent medially
4. increased lateral talocalcaneal angle with talus plantarflexed on calcaneus

Due to persistent foot pain and excessive callus formation over the medial arch the patient was taken to the OR and underwent surgical treatment of the left foot. The procedure consisted of :

1. subtalar arthrodesis with autograft bone graft and screw fixation
2. closing wedge calcaneocuboid arthrodesis with open pinning
3. reduction and open pinning of the talonavicular joint
4. midfoot soft tissue release of the talonavicular, calcaneocuboid and subtalar joints

Post operatively, the patient was placed in a long leg cast. Preliminary results show satisfactory reduction of the talonavicular joint, correction of hindfoot valgus, dorsiflexion of the talus on the calcaneus, and correction of forefoot adduction immediately post op.

REVIEW OF SKEWFOOT DEFORMITY:

Definition - also known as serpentine foot, Z foot , Zed foot

-foot deformity consisting of forefoot adduction and plantarflexion, hindfoot valgus, and

lateral displacement of the midfoot characterized by lateral displacement of the navicular

on the talar head

GENERAL FEATURES:

• deformity lies along the continuum of metatarsus adductus and hindfoot valgus
• incidence is rare but may be more common then reported if milder forms are included,as there are no absolute criteria for the diagnosis of skewfoot
• resistant metatarsus adductus may be a presentation of skewfoot

CLINICAL FEATURES:

• most obvious features are forefoot adduction and hindfoot valgus
• prominence of the talar head in the medial arch with possible flattening of the medial arch and presence of thickened callus over the head of the plantarflexed talus
• tendoachilles contracture of variable degree
• deformity may be rigid or supple

RADIOGRAPHIC FEATURES:

1. lateral displacement of the navicular on the head of the talus

-navicular ossification however does not occur until 1-2 yrs in females and yrs in males

1. metatarsal adduction
2. line drawn through the long axis of the first metatarsal and line drawn through the long axis of the talus should be parallel or divergent laterally in the normal foot on AP radiograph
3. widening of the talocalcaneal angle on AP radiograph- usually greater than 35 degrees
4. increased lateral talocalcaneal angle with planterflexion of the talus

TREATMENT:

NONOPERATIVE TREATMENT

• serial casting is the mainstay of nonoperative care: application of the cast is similar to that for metatarsus adductus, but the heel is held in neutral to slight varus
• successful nonoperative treatment would constitute improvement of foot appearance, reasonable correction of radiographic features
• cast treatment for skewfoot is longer duration than that needed for metatarsus adductus
• usual serial casting for approximately 8-10 weeks and 2-4 weeks of static casting

OPERATIVE TREATMENT

usually not indicated until early childhood, but there are no studies which delineate the optimal time for surgery

PROBLEMS TO ADDRESS WITH SURGICAL CORRECTION:

1. forefoot adduction
2. deformity of the medial cuneiform tissue contracture-Achilles, toe flexors, tibialis posterior, plantar fascia
3. lateral displacement of the navicular
4. lateral displacement and valgus of the calcaneus
5. increased lateral column length

-all of this deformities are variable in severity

Coleman recommends: opening wedge osteotomy of the medial cuneiform,plantar fascia release, and possible lateral column lengthening (1)

Kendrick and Herndon: subtalar fusion or triple arthrodesis with forefoot correction (2)

Mosca: lateral calcaneal lengthening with trapezoidal graft, plantarmedial opening of the medial cuneiform to correct forefoot adduction (3)

GENERAL CONSIDERATIONS FOR OPERATIVE TREATMENT (4)

• younger children consideration should be given to soft tissue releases and limited bony procedures particularly if the foot is flexible
• older children should consideration should be given to the procedures above and possible oblique calcaneal osteotomy to correct hindfoot valgus
• adolescents- triple arthrodesis combined with multiple metatarsal osteotomies and soft tissue releases

CONCLUSIONS ON OPERATIVE TREATMENT:

• skewfoot is a complex deformity and no one procedure can address the spectrum of deformities nor can one procedure be applied to all age groups
• operative treatment therefore should be planned according to the physical exam in combination with the known radiographic abnormalities.

REFERENCES:

1. Coleman SS. Complex Foot Deformities in Children Philadelphia: Lea & Fibiger, 1983:267
2. Kendrick RE, Sharma NK, Hassler WL, Herndon CH., Tarsometatarsal Mobilization for Resistant Adduction of the Forepart of the Foot. JBJS (AM) 1970;52:61
3. Mosca V. Calcaneal Lengthening for Valgus Deformity of the Hindfoot, JBJS (AM) Vol. 77-A, No 4:500
4. Lovell and Winter's Pediatric Orthopaedics- 3rd ed., Vol. 2 Philadelphia p.998-1001
5. Berg E., A Reappraisal of Metatarsus Adductus and Skewfoot JBJS (AM) Vol. 68-A, No 8:1185