SKEWFOOT

CHARLES J. ODGERS, M.D., Resident, Orthopaedic Surgery

ROBERT P. STANTON, M.D., Attending Pediatric Orthopaedic Surgeon

April 10, 1996

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

CASE HISTORY:

A 2+1 year-old boy was seen at A.I. duPont Institute for evaluation of intoeing. He had been previously diagnosed with bilateral metatarsus adductus at another institution. His prior treatment consisted of serial casting for eight weeks begun shortly after birth, followed by corrective shoes until age 12 months. His parents felt that the metatarsus adductus had improved since birth, however they still had concerns over the residual deformity. They denied that their child had any functional problems. There was a positive maternal family history of "intoeing" which was treated with a Dennis Browne bar and corrective shoes.

Initial Exam

Examination revealed a well-appearing child. He had bilateral mild internal tibial torsion, however the major component of his intoeing appeared to be secondary to bilateral metatarsus adductus deformities which were supple and flexible and they were both able to be corrected to neutral position.

Disposition

The patient did not have x-rays of his feet at this time. The working diagnosis remained metatarsus adductus, and the patient was recommended to wear straight last shoes to see if that would obtain further correction. He was told to return in six months at which time AP and lateral x-rays of both feet would be obtained.

Follow-up

The patient returned for follow-up, now 5+1 years-old. His mother stated that he still had residual intoeing, and he appeared more clumsy with gait than other children his age. She was concerned that his metatarsus adductus had not corrected, and she wanted to know if anything more could be done. The patient still had not had any functional problems, nor had he any shoewear problems. Examination revealed bilateral flexible metatarsus adductus deformities. There was no evidence of any skin breakdown or callous formation. He did have a noticeable valgus right heel with a less obvious left heel valgus deformity. His subtalar motion was maintained. AP and lateral standing radiographs were obtained.

SKEWFOOT

Introduction

• Rare complex foot deformity of malalignment of the tarsals and metatarsals
• Recognized clinically by forefoot adduction and hindfoot valgus
• Originally coined by McCormick and Blount in 1949
• Synonyms include S-shaped foot , serpentine foot, and Z-foot deformity
• Never been recorded at birth- often discovered after cast treatment for metatarsus adductus or clubfoot
• Problem- Many unknown variables with this condition including the definition, prevalence, etiology, natural history , and treatment

Definition

• Inconsistent terminology
• 1933- Peabody and Muro - labeled foot shape congenital metatarsus varus and differentiated it from more common and benign congenital metatarsus adductus
• 1949- McCormick and Blount- used skewfoot to describe a group of foot deformities including metatarsus adductus, metatarsus varus, metatarsus adductovarus, and metatarsus adductocavovarus
• 1950- Kite- identified nine feet in series of 300 with benign forefoot adduction characterized by severe forefoot adduction and fixed heel valgus angulation which were very resistant to treatment- called them metatarsus adductus and later renamed serpentine metatarsus adductus

Clinical Features

• Presenting complaints- most often shoewear and abnormal gait
• Forefoot adducted and increased heel valgus( +/- Achilles tendon contracture)
• Can develop painful callosities and bursa

Radiographic Evaluation

• No universally accepted clinical or radiographic criteria for defining relationships of forefoot and hindfoot in flatfoot, skewfoot, or metatarsus adductus- how much forefoot adduction needed to reclassify flatfoot as skewfoot?
• 1986-Berg- first attempt to classify metatarsus adductus and skewfoot radiographically- many faults of study
1. Radiographs of children from two to seventeen months of age when bone ossification is limited and irregular
2. Made gross assumptions regarding position of unossified navicular, a key element in his classification system
3. Cook et al.- found large inter- and intraobserver disagreement using this classification system
• Medial angulation of the talus-1^st metatarsal line - indicative of forefoot adduction
• Increased Kite's talocalcaneal angles on AP(>35) and lateral(>45)- indicative of hindfoot valgus
• Lateral subluxation of navicular bone on talus

Etiology-unknown

• Early authors believed skewfoot resulted from improper use of cast in attempt to correct clubfoot and metatarsus adductus deformities
• Peabody and Muro- muscle balance resulting from variation in the insertion of the tibialis anterior

Natural History- unknown

• Do some patients have spontaneous correction with time as with metatarsus adductus and flexible flatfoot?
• Prevalence of long term disability?
• Fact- some patients clearly have pain, callosities, and difficulty wearing shoes as early as 1^st decade

Treatment

• Role of manipulations and serial casting- consider only if discovered during infancy
• Symptomatic non-operative treatment- modifications in shoewear
• Surgical treatment- Indicated in older patients who have failed conservative treatment- most suggestions have been based on theory- need to correct all components of deformity
1. Peterson - combined tarsometatarsal capsulotomies with concurrent Grice subtalar arthrodesis- good result however only three patients
2. Coleman- proposed medial cuneiform opening-wedge osteotomy with plantar fasciotomy- does not address hindfoot deformity
3. Mosca-Used combination of calcaneal lengthening osteotomy(modified Evan's technique), medial cuneiform opening wedge osteotomy, and Achilles lengthening- 9 of 10 satisfactory results- technique preserves motion of all joints- only short term follow-up

REFERENCES:

1. Berg E: A reappraisal of metatarsus adductus and skewfoot. J. Bone and Joint Surg., 68-A:1195-1196, Oct. 1986.
2. Coleman S: Complex Foot Deformities in Children, pp. 267-272. Philadelphia, Lea and Febiger, 1983.
3. Kite J: Congenital metatarsus varus. Report of 300 cases. J. Bone and Joint Surg., 32-A: 500-506, July 1950.
4. McCormick D, and Blount W: Metatarsus adductovarus. "Skewfoot". J. Am. Med. Assn., 141:449-453, 1949.
5. Mosca V: Calcaneal lengthening for valgus deformity of the hindfoot. Results in children who had severe, symptomatic flatfoot and skewfoot. J. Bone and Joint Surg., 77-A:500-512, April 1995.
6. Peabody C, and Muro F: Congenital metatarsus varus. J. Bone and Joint Surg., 15:171-189, Jan. 1933.
7. Peterson H: Skewfoot(forefoot adduction and heel valgus). J. Pediat. Orthop., 6:24-30, 1986.