Congenital Cleft Foot & Overlapping/Underlapping Fifth Toe

Across the spectrum from a mild central cleft to severe loss of multiple rays, the classification that matters is the typical vs atypical distinction, which carries the inheritance and counselling implications:

• Typical cleft foot (true central-ray deficiency / SHFM). A central, V-shaped cleft from deficiency of the central ray(s), frequently bilateral, often with split-HAND involvement, and commonly familial (autosomal dominant with variable expressivity and incomplete penetrance - so a mildly affected parent may have a severely affected child). This is the form linked to the SHFM loci (e.g. SHFM3/10q24) and to EEC syndrome - the form for which genetic counselling is most relevant.
• Atypical cleft foot (now usually termed symbrachydactyly). A wider, U-shaped defect with more rays absent (sometimes a near-monodactylous foot), typically unilateral and sporadic (not inherited and not part of the SHFM genetic spectrum) - so the recurrence risk and counselling differ. Modern usage prefers "symbrachydactyly" over "atypical cleft."
• Grading severity. Foot-specific schemes grade by the number of remaining rays/metatarsals and the presence of transverse bones, which guides whether reconstruction (cleft closure, syndactyly release, ray realignment) or simply accommodative footwear is appropriate.

So the first classifying question - typical (central, often bilateral/familial, hand-associated) versus atypical/ symbrachydactyly (U-shaped, unilateral, sporadic) - directly shapes the genetic counselling. (The split-HAND counterpart and its Manske classification are covered in our Cleft Hand topic.)

Grading the foot itself. The named scheme is the Blauth and Borisch classification, which grades cleft foot by the number and morphology of the metatarsals remaining (from a foot with all five metatarsals present and only a soft-tissue cleft, through progressive central metatarsal absence, to a severely monodactylous foot). It is useful because the count, rather than the appearance of the cleft, is what predicts whether the foot needs nothing more than accommodative footwear or a genuine reconstruction.

Naming what you are looking for in EEC. "Assess for syndromic features" is only useful if you can say what they are. EEC is Ectrodactyly, Ectodermal dysplasia and Clefting, most often from a TP63 mutation:

• Ectodermal dysplasia - sparse fine hair, abnormal or absent teeth, dystrophic nails, dry skin and reduced sweating.
• Clefting - cleft lip and/or palate.
• Lacrimal duct obstruction - a characteristic and easily missed feature causing chronic tearing and recurrent eye infection; ask about it specifically.
• Genitourinary and renal anomalies - warranting a renal ultrasound.
• Conductive or sensorineural hearing loss - so arrange a hearing assessment.

Examine the hands in every cleft foot, and refer to clinical genetics: the inheritance is autosomal dominant with variable expressivity, so a parent with a trivially abnormal hand may not know they carry it.

• The Butler procedure is the classic operation for the congenital overriding (overlapping) fifth toe: a double racquet-shaped (dorsal and plantar) incision around the base of the toe lets the extensor tendon and the dorsal MTP capsule be released so the toe is repositioned plantarward and into the corrected alignment, with the skin closure holding the new position. It corrects the deformity while preserving the toe (in contrast to amputation).
• Percutaneous flexor tenotomy is the simple, effective procedure for the flexible underlapping ('curly') toe - dividing the tight flexor digitorum longus (and brevis) through a tiny stab releases the flexion/ curl; it works well in children and avoids open surgery.
• Syndactylisation (suturing the fifth toe to the fourth, a Kelikian-type "buddy" procedure) is an option for a recurrent or unstable toe.
• Bone procedures - phalangectomy (removing the proximal phalanx) or a corrective osteotomy - and, rarely, amputation of the fifth toe are reserved for severe, recalcitrant or salvage situations.
• Choosing. Match the procedure to the pathology: a fixed dorsal-adduction overriding toe needs the soft-tissue release/repositioning of a Butler, whereas a flexible curly toe needs only a flexor tenotomy - consistent with there being no single gold-standard operation. (General lesser-toe and curly-toe surgery is covered in our Lesser Toe Deformities and Curly Toes topics.)

The definition and genetic heterogeneity of cleft foot/split-foot malformation (central-ray deficiency, 'lobster-claw', SHFM3/10q24, isolated vs syndromic) and the importance of genetic counselling come from the cited Lai report (with the cited Raza case report illustrating function-and-cosmesis-tailored surgical management of ectrodactyly, PMID 41013550); the descriptions and management of the overlapping and underlapping fifth-toe deformities (largely non-operative in children with surgery for persistent symptoms, and no gold-standard procedure) from the cited Talusan review. The EEC syndromic association and the assessment of the hands/associated anomalies are standard, well-established teaching. (See also our Polydactyly/Syndactyly and Paediatric Foot Deformities topics.)