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RADIAL DEFICIENCES

Introduction

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 aminopterin2,5

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 births6,7
    • 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
ICD-10 Codes

  • RADIAL DEFICIENCES (RADIAL CLUB HAND)

    Diagnostic Guide Name

    RADIAL DEFICIENCES (RADIAL CLUB HAND)

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    RADIAL DEFICIENCES (RADIAL CLUB HAND) Q71.42Q71.41Q71.43

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
  • Radial Deficiency (Radial Agenesis)
    Radial Deficiency (Radial Agenesis)
Symptoms
Hand, wrist forearm and elbow deformity
Small or missing thumb
Joint stiffness
Impaired pinch and grip
Other functional impairments
Typical History

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.

Positive Tests, Exams or Signs
Work-up Options
Treatment Options
Conservative
  • Treatment should include both conservative and surgical interventions and start as soon as possible after birth.8
  • Splinting
    • Will help to stretch the tight soft tissues and radial structures, allow passive correction of the deformity by aligning the hand and wrist with the ulna, and prevent further deformity
    • Serial casting and splinting should ideally be located above the elbow for increased control due to the small size of the limb
    • Generally well tolerated for the first 6 months of age, but usually becomes less effective and tolerated later in life
  • Serial casting
    • May also be used in a similar manner to splinting to stretch tight structures on the radial side
    • Physical and/or occupational therapy is important component of all treatment protocols, particularly before and after surgery.
      • Before surgery, a thorough rehabilitation musculoskeletal evaluation should be performed to describe, predict, and maximize hand and upper extremity function. The evaluation should include the status of all proximal and distal joints and their active use in functional tasks5
  • Physical therapy should also included:
    • Active and passive range of motion (ROM) exercises
    • Adequate preoperative soft-tissue stretching is a prerequisite for a successful surgical procedure and should be carried out rigorously until the time of surgery2
Operative
  • Typically needed in most cases, with its goal being to maintain a straight wrist and restore any shortening of the extremity8,10
  • Centralization is the standard treatment to correct radial deviation
    • Indications
      • Types II, III, and IV
      • Persistent radial deviation deformity and insufficient support of the carpus
      • Good elbow motion with biceps function intact
    • May be performed along with radial soft tissue release or transfer of the flexor and extensor carpi radialis tendons to the ulnar side
    • Typically performed between 6 and 18 months of age
    • Centralization is contraindicated in older patients with good function, in patients with unacceptable surgical and anaesthetic risks because of associated medical problems, and in patients with elbow extension contracture who rely on radial deviation for eating etc.
    • Requires an ulnar-sided capsulotomy, release of the radial capsule, and contracted radial-sided tendons, and reduction of the carpus onto the ulna, which may require an ulnar shortening osteotomy10
  • Radialization
    • Should include the release of tight radial soft tissue structures along with possible tendon transfers from the radial to the ulnar side of the             wrist
    • Pre-operative serial casting and splinting should be done.
    • Radial lengthening
      • Should be started 5 days after surgery
      • The recommended lengthening rate is 0.25-0.5 mm per day, depending on the condition of bony formation on X-ray, which is to be evaluated each week
      • Both external fixators are removed after complete bone formation2,10
      • Ilizarov ulnar lengthening with external fixation distraction has been indicated for moderate to severe length discrepancies to assist in gaining length for activities of daily living and cosmetic reasons5
  • Ulnar osteotomy
    • May be needed in cases of significant ulnar bowing toward the radial side5
  • Pollicization in cases with an abscence thumb
  • Other procedures that are sometimes used for radial defificienct included:
    • May be considered as a secondary reconstruction when the thumb is absent5
    • Soft tissue distraction
    • Vascularized epiphysis
    • Dorso-radial muscle transfer3
    • Ulnocarpal arthrodesis after growth has stopped to correct residual deformities10
Hand Therapy
  • 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
Complications
  • Infection
  • Recurrence of deformity
  • Stress on neurovascular structures
  • Edema
  • Surgical overcorrection
  • Growth plate arrest in the distal ulna
Outcomes
  • 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
Key Educational Points
  • 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.
References
  • 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.
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