4.9h Limb Deficiency: Longitudinal Axial Limb Deficiency – Split Hand and Foot (Q71.6, Q72.7)

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The longitudinal axial or split hand/split foot deficiency is characterized by a deficiency of the central digits/toes often involving the associated carpal/tarsal bones, leading to the typical external appearance that gave rise to the name split hand or split foot (see Fig. 4.41).

Fig. 4.41. Split hand and foot

Relevant ICD-10 codes

Q71.6 Congenital cleft hand
Q72.7 Split foot

Note: Avoid using the generic Q71, Q72 or Q73 codes for split hand and split foot. These generic codes include other limb reduction defects.

Diagnosis

Prenatal. Split hand and split foot might be diagnosed or strongly suspected prenatally. However, they can be missed. Moreover, the distinction from other limb deficiencies is difficult and error-prone. For this reason, a prenatal diagnosis should always be confirmed postnatally.

When this is not possible (e.g. termination of pregnancy or unexamined fetal death), the programme should have criteria in place to determine whether to accept or not accept a case based solely on prenatal data.

Postnatal. The newborn examination can identify the typical external appearance of this condition, although on occasion there is confusion with terminal transverse deficiencies involving the middle fingers. An accurate and complete diagnosis requires a detailed physical examination aided by radiography to characterize completely the bony anatomy of the axial (central) segments of the hands and feet.

Clinical and epidemiologic notes

Note that older terms such as ectrodactyly and lobster claw hands have been used in the past but should be avoided, as these are either imprecise or pejorative.

Cases of split hand or split foot can occur with syndactyly and hypoplasia of some of the remaining digits. The most severe form of split hand or split foot is monodactyly, where the hand or foot only has a single digit.

This condition can involve only the hands, only the feet, or both the hands and feet. Hands are affected much more frequently than feet. Most cases are unilateral, with the right side more commonly affected.

Split hand and split foot might occur with deficiency of the adjacent long bones of the limbs.

Split hand/split foot is part of a large group of syndromes due to one of several single-gene conditions or genomic rearrangements, some of which involve other organ systems. Examples include the EEC syndromes (ectrodactyly, ectodermal dysplasia, cleft lip/palate), and the limb-mammary syndrome (split hand split foot, absence of breast tissue, cleft palate).

The prevalence of axial limb deficiencies is around 0.15 per 10 000 births.

Inclusions

Q71.6 Congenital cleft hand
Q72.7 Split foot

Exclusions

Q68.10 Clinodactyly
Q70 Syndactyly
Q71.3 Congenital absence of hand and finger(s)
Q71.30 Congenital absence of finger(s)
Q71.31 Absence or hypoplasia of thumb (other digits intact)
Q72.3 Congenital absence of foot and toe(s)
Q72.30 Congenital absence or hypoplasia of toe(s) with remainder of foot intact
Q72.31 Absence or hypoplasia of first toe with other digits present

Q74.80 Brachydactyly

Checklist for high-quality reporting

Checklist for high-quality reporting
Split Hand and Foot – Documentation Checklist
Describe in detail, including: Limbs involved. Note each segment involved for each limb affected – describe what is deficient or absent. Indicate involvement of digits and toes (third, with or without second and fourth). Laterality – right, left, bilateral. Document specialty consultations (e.g. genetics, orthopaedics). Use Fig. 4.35 to distinguish longitudinal axial defects from other subtypes of limb deficiencies. Describe procedures to assess further additional malformations and, if one or more is present, describe these. Describe procedures to assess syndromes. Distinguish from other longitudinal and transverse limb deficiencies (e.g. transverse terminal deficiencies of fingers or toes). Take and report photographs: Very useful; can be crucial for review. Take and report radiographs: Crucial for review and classification, at times even more so than photographs. Report whether specialty consultation(s) done, and if so, report the results.

Suggested data quality indicators

Suggested data quality indicators
Category	Suggested Practices and Quality indicators
Description and documentation	Review sample for documentation of key descriptors: Take and attach radiographs and photographs – essential for review and correct classification. Specify which limbs are involved and laterality. Specify affected segments (fingers, toes). Specify affected bones.
Coding	Track and minimize cases coded with generic ICD-10 RCPCH codes: Q71, Q72, Q73.
Clinical classification	Syndromes are frequent in axial defects. A low proportion of syndromes suggests misclassification with other limb deficiencies
Prevalence	Prevalence is around 0.15 per 10 000. A higher prevalence suggests misclassification with transverse terminal defects of fingers or toes.
Key visuals	Distinguishing longitudinal axial defects from transverse terminal defects of hand/foot (side-by-side comparison):