Classification of Limb Anomalies

•  Numerous classification systems exist for upper extremity limb anomalies based on embryology, teratologic sequencing, and/or anatomy. Each proposal has merit at the time of its inception, although many systems become

Table 30-1: Signaling Pathways During Embryogenesis

SIGNALING CENTER

RESPONSIBLE SUBSTANCE

ACTION

Apical ectodermal ridge

Fibroblast growth factors

Proximal to distal limb development, interdigital necrosis

Zone of polarizing activity

Sonic hedgehog protein

Radioulnar limb formation

Wingless-type (Wnt) pathway

Lmx-1

Dorsalization of the limb

Table 30-2: Embryologic Classification of Congenital Anomalies

CLASSIFICATION

SUBHEADING

SUBGROUP

CATEGORY

I. Failure of formation

A. Transverse arrest

1.  Shoulder

2.  Arm

3.  Elbow

4.  Forearm

5.  Wrist

6.  Carpal

7.  Metacarpal

8.  Phalanx

B. Longitudinal arrest

1.  Radial deficiency

2.  Ulnar deficiency

3.  Central deficiency

4.  Intersegmental

Phocomelia

II. Failure of differentiation

A. Soft tissue

1. Disseminated

A. Arthrogryposis

2.  Shoulder

3.  Elbow and forearm

4.  Wrist and hand

A.  Cutaneous syndactyly

B.  Camptodactyly

C.  Thumb-in-palm

D.  Deviated/deformed digits

B. Skeletal

1. Shoulder

2. Elbow

Synostosis

3. Forearm

A.  Proximal

B.  Distal

4. Wrist and hand

A.  Osseous syndactyly

B.  Carpal bone synostosis

C.  Symphalangia

D.  Clinodactyly

C. Tumorous conditions

1.  Hemangiotic

2.  Lymphatic

3.  Neurogenic

4.  Connective tissue

5.  Skeletal

III. Duplication

A.  Whole limb

B.  Humeral

C.  Radial

D.  Ulnar

1. Mirror hand

E. Digit

1. Polydactyly

A.  Radial (preaxial)

B.  Central

C.  Ulnar (postaxial)

IV Overgrowth

A.  Whole limb

B.  Partial limb

C.  Digit

1. Macrodactyly

V Undergrowth

A.  Whole limb

B.  Whole hand

C.  Metacarpal

D.  Digit

1.  Brachysyndactyly

2.  Brachydactyly

VI. Constriction band syndrome

VII. Generalized skeletal abnormalities

Outdated as our understanding of embryogenesis and genetics expands.

The most widely accepted classification of congenital limb anomalies is based on embryonic failure during development and relies on clinical diagnosis for categorization. Each limb malformation is classified according to the most predominant anomaly and placed


Into one of seven categories (Table 30—2). Different clinical presentations within similar categories are explained by variable degrees of damage. This classification scheme represents a valiant attempt to comprehensively classify congenital anomalies.

• However, valid criticisms of this system have arisen concerning the difficulty with classifying the


“predominant” deformity and the inability to categorize peculiar anomalies. Also, several authors have noted numerous similarities and differences between various congenital anomalies, creating conflict within this embryologic failure classification scheme.4-6

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