RADIAL DEFICIENCES

Radial deficiencies (also called radial agensis or radial club hand) are rare and complex congenital abnormalities of the radial or pre-axial border of the upper extremity. This deformity is often bilateral with varying degrees of radial and thumb hypoplasia on the right and left sides. The most recognized of these is radial club hand, a term that describes a longitudinal deficiency in which the hand is radially deviated at the distal forearm due to the absence of the radius.  This creates a characteristic radial club hand appearance. These radial deficiencies, however, are more complex and varied and can be defined as any degree of congenital hypo/aplasia of the thumb, thenar muscles, first metacarpal bone, radial carpal bones and/or radius. Radial deficiencies may range from mild cases of hypoplasia of the thumb to complete absence of the radius and first ray. Apart from the severe aesthetic defect, radial deficiencies usually lead to functional deficits due to the shortened forearm, unstable wrist, and reduced extrinsic tendon course, and other congenital malformations are also commonly present. Treatment should begin as soon as possible after birth and include both conservative and surgical interventions, with surgery being an appropriate recommendation for many patients.^1-4,8

Pathophysiology

• All radial deficiencies are categorized in the embryological class of formation defects, in which the primary event is a localized developmental failure due to genetic or non-genetic factors⁴
  • The cause of deficiency is thought to be related to a mesodermal developmental error due to defects in the sonic hedgehog (SHH) signaling pathway²
    • The insult responsible for causing a radial deficiency, whether environmental or genetic, likely occurs between weeks 4-5 of embryonic development, during which time the upper limbs form²
    • The development of the radio-ulnar axis is controlled by the secretion of the SHH gene from the zone of polarizing activity along the ulnar axis of the limb bud; a progressive loss of SHH expression reduces limb outgrowth, volume, and width
    • When the loss of SHH reduces the fibroblast growth factor (FGF) expression through the interruption of the SHH-FGF loop, the resulting phenotype involves a disruption of both ulnar and radial structures, particularly the thumb
    • In cases where the proliferation and ulnarization persist, but there is a decrease in the FGF function, the resulting phenotype is similar to the radial deficiencies spectrum⁴
    • Most cases of radial deficiency occur as sporadic events, although cases in which more than one family member is affected have been reported²
    • The occurrence of radial deficiency is associated with autosomal dominant inheritance, constriction bands, genetic syndromes, and environmental factors such as viral infection and maternal exposure to antiepileptic drugs—particularly valproic acid—phenobarbital, and aminopterin^2,5

Related Anatomy

• Radial, median and ulnar nerves
• Radial artery
• Carpus
• Thumb ray
• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Pronator teres
• Flexor carpi radialis
• Palmaris longus
• Flexor pollicis longus
• Pronator quadratus
• Supinator
• Metacarpophalangeal (MP) joints
• Interphalangeal (IP) joints

The most commonly used classification system places radial deficiencies into 4 types based on radiographic severity:^1,8

• Type I: Short distal radius
  • The radius is slightly shorter than the ulna
  • Distal growth plate is present
  • Minor radial deviation of the hand is apparent, and considerable thumb hypoplasia may be evident

• Type II: Hypoplastic radius
  • Radius is smaller or thinner than the ulna
  • No growth plate is present
  • Moderate radial deviation of the wrist with proximal radial hypoplasia, carpal bones changes, and thumb hypoplasia or abscence
• Type III: Partial absence of the radius
  • Only a small proximal radial segment is present
  • Severe radial deviation of wrist with significant proximal radial hypoplasia, carpal bones changes, and thumb hypoplasia or abscence
• Type IV: Total absence of radius
  • The most common variant
  • Radius is completely absent
  • Hand develops a perpendicular relation to the forearm
  • Thumb hypoplasia or abscence with carpal abnormailitis
  • Ulna may be curved¹

An alternative, modified classification system has also been developed more recently that incorporates the thumb, carpus, and forearm:⁸

• Type N: Normal radius and carpus with thumb deficiency
• Type 0: Absent or hypoplastic carpal bones with normal length radius
• Type I: Distal portion of the radius is >2 mm shorter than the distal portion of the ulna
• Type II: Radius is hypoplastic in its entirety and often associated with bowing of the ulna
• Type III: Distal part of the radius is absent
• Type IV: Completely absent radius
• Type V: Radial longitudinal deficiency with extremities with abnormal glenoid, absent proximal portion of the humerus, distal portion of the humerus articulates with ulna, radial-sided hand abnormalities⁴

Incidence and Related Conditions

• The incidence of all radial deficiencies is ~1 in 9,000-55,000 live births^6,7
  • The incidence of radial club hand specifically is ~1 in 50,000-100,000 live births⁸
  • Radial deficiencies are about 4-10 times more common than ulnar deficiencies⁹
  • The prevalence of radial deficiencies is slightly higher in boys than girls (3:2)²
  • Radial deficiencies represent 25–33% of all congenital upper limb anomalies⁴

Related Conditions

•  
• VACTERL (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities) syndrome
• Syndromes: Holt-Oram, Duane-radial ray, Thrombocytopenia-absent radius, Lacrimo-auriculo-dento-digital, Townes-Brocks, Baller-Gerold
• Fanconi anemia which can cause severe, sometimes fatal, pancytopenia which is treatable by bone marrow transplant if diagnosed early.
• Nager acrofacial dysostosis
• Congenital heart disease
• Craniofacial anomalies
• Congenital scoliosis
• Mental retardation
• Chromosomal aberrations
• Cleft palate
• Clubfoot
• Kyphosis
• Torticollis
• Rib deformities

Differential Diagnosis

• Thrombocytopenia-absent radius syndrome
• Fanconi anemia
• Holt-Oram syndrome
• VACTERL sydrome

The typical patient is a 14-month-old boy with an associated secondary congenital syndrome. Before the boy was born, ultrasound findings revealed a partially absence of a radius in his left arm, as well as several other anatomical anomalies. At birth the child was immediately diagnosed with a significant left radial deficiency.  The left thumb was present but smaller than the more normal right thumb. His left hand appeared perpendicular to his wrist.  The boy went on to have severe functional and developmental impairments that restricted and slowed his early development. This led his parents to seek further treatment. Their hand surgeon agreed with the diagnoses of left radial deficiency and hypoplastic thumb.  The patient was noted to have a functional arc of motion in the flexion/extension plane of the left elbow. Initially the patient had serial casting.  Shortly after his first birthday the patient underwent a centralization procedure on the left.  In his early teenage years the patient had an ulnar lengthening performed.  At age twenty the patient had a left wrist fusion.

• Postoperative rehabilitation
  • Should be based on the phases of wound healing, and the protocols of stabilization procedures should be employed
  • The goal of rehabilitation is a stable, centralized joint, and immobilization is very important
  • Proximal active and passive ROM exercises should begin 1-2 days postoperatively, with full digital tendon gliding exercises started as soon as indicated by the surgeon⁵

• Infection
• Recurrence of deformity
• Stress on neurovascular structures
• Edema
• Surgical overcorrection
• Growth plate arrest in the distal ulna

• Soft tissue distraction was found by some authorities to be an effective initial intervention for severe radial club hand³
• Ulnocarpal arthrodesis was found to achieve union in 11 of 12 patients with recurrent radial club hand deformity within four months, and patients and parents were satisfied with function and appearance¹⁰

• To date, there is no established solution for mild radial deficiencies, but one suggested approach is radius lengthening accompanied by a soft-tissue distraction or release at the ulnar carpal joint with keeping wrist and forearm motion without producing growth plate damage²
• Splinting and stretching are not as effective by 2-3 years of age, but since limbs grow to about double their size at birth by this time, subsequent operative treatments are easier²
• Severe radial club hand is difficult to treat, and the main objectives in these cases are to stabilize the carpus in alignment with the forearm and improve both aesthetics and function by enhancing flexor digitorum force and upper extremity length³
• Primary radial deficiencies mostly remain confined to the radial side of the arm, extending to the ulna only in the extreme forms when the radii are severely affected⁴
• In general, the severity of the thumb deficiency in affected patients is directly proportional to the severity of the radial deficiency⁴
• Recurrence of deformity after centralization is common and expected.
• Children with stiff elbows, bilateral involvement, absent thumbs, and/or stiff fingers should be evaluated carefully before recommending centralization.¹⁰
• Recommendations to decrease the likelihood of deformity recurrence after radial deficiency treatment include the following:^2,8
  • Release radial structures, taking care to protect the anomalous median nerve, and to transfer the radial wrist extensors to minimize the deforming forces casued by these extensor tendons.
  • Release joint structures cautiously, with centralizing or radializing to avoid undue cartilage compression and damage to the distal ulnar epiphysis 
  • After centralization a Steinman pin is  used to hold the alignment of the wrist for 6- 8 weeks.  Some authorities recommend leaving this pin permanently.
  •  Steinman pin(s) are also used after osteotomy for correcting severely bowed ulnar shafts especially in the case of complete radial absence¹⁰
  •  Pin complications are common in these complex surgical cases.
• Given the high incidence of associated syndromes, each patient's evaluation should include a work-ukp of the spine, kidney, heart and blood. Spinal X-rays, EKG possible with a cardiac consult, renal ultrasound and CBC should all be considered for these patients.
• In radial deficiencies the affected forearm and hand can be half the length of the normal side.⁸
• On the radial side of the wrist the median nerve will not be in a normal anatomic location and is often a prominent structure while the radial artery may even be abscence.
• Carpal shortening or ulnar shortening without damaging the distal ulnar epiphysis may be needed in order to complete a centralization.

Cited

1. Bayne LG, Klug MS. Long-term review of the surgical treatment of radial deficiencies. J Hand Surg Am 1987;12(2):169-79. PMID: 3559066
2. Takagi T, Seki A, Takayama S, Watanabe M. Current Concepts in Radial Club Hand. Open Orthop J 2017;11:369-377. PMID: 28603568
3. Romana C, Ciais G, Fitoussi F. Treatment of severe radial club hand by distraction using an articulated mini-rail fixator and transfixing pins. Orthop Traumatol Surg Res 2015;101(4):495-500. PMID: 25907512
4. Elmakky A, Stanghellini I, Landi A, Percesepe A. Role of Genetic Factors in the Pathogenesis of Radial Deficiencies in Humans. Curr Genomics 2015;16(4):264-78. PMID: 26962299
5. Brooks C. Rehabilitation of radial club hand. Tech Hand Up Extrem Surg 1998;2(1):78-85. PMID: 16609488
6. Lourie GM, Lins RE. Radial longitudinal deficiency. A review and update. Hand Clin 1998;14(1):85-99. PMID: 9526159
7. Tonkin MA. Congenital hand deformities: major limb defects. In: Green DP, Hotchkiss RN, Pederson WC, eds. Green’s operative hand surgery. 4th ed. Philadelphia: Churchill Livingstone, 1999: pp. 338–368.
8. James MA, Bednar MS. Malformations and deformities of the wrist and forearm. In: Wolfe SW, Hotchkiss RN, Pederson WC, Kozin SH, Eds. Green’s Operative Hand Surgery. 6th ed. Philadelphia: Elsevier 2011: pp. 1405-34.
9. James MA, Bednar MS. Deformities of the wrist and forearm. In: Green DP, Hotchkiss RN, Pederson WC, Wolfe SW, eds. Operative hand surgery. 5th ed. New York: Churchill Livingstone, 2005: pp. 1469–1506.
10. Comer GC, Ladd AL. Management of complications of congenital hand disorders. Hand Clin 2015;31(2):361-75. PMID: 25934210

New Articles

1. Romana C, Ciais G, Fitoussi F. Treatment of severe radial club hand by distraction using an articulated mini-rail fixator and transfixing pins. Orthop Traumatol Surg Res 2015;101(4):495-500. PMID: 25907512
2. Elmakky A, Stanghellini I, Landi A, Percesepe A. Role of Genetic Factors in the Pathogenesis of Radial Deficiencies in Humans. Curr Genomics 2015;16(4):264-78. PMID: 26962299

Reviews

1. Takagi T, Seki A, Takayama S, Watanabe M. Current Concepts in Radial Club Hand. Open Orthop J 2017;11:369-377. PMID: 28603568
2. Comer GC, Ladd AL. Management of complications of congenital hand disorders. Hand Clin 2015;31(2):361-75. PMID: 25934210

Classics

1. Lamb DW. The treatment of radial club hand. Absent radius, aplasia of the radius, hypoplasia of the radius, radial paraxial hemimelia. Hand 1972;4(1):22-30. PMID: 5061371
2. Define D. Treatment of congenital radial club hand. Clin Orthop Relat Res 1970;73:153-9. PMID: 5479772