Pretest

Introduction

Radial club hand is classified as a pre-axial longitudinal deficiency. The axis of the forearm lies along the middle finger; the radial side is considered pre-axial and the ulnar side is post-axial. Radial club hand is a congenital deformity that occurs in 1 of 30,000 to 100,000 live births. The deformity consists of radial hypoplasia or absence, thumb hypoplasia or absence, radiocarpal hypoplasia or absence, radial deviation of wrist, and varying degrees of neuromuscular deficiencies. Bilateral involvement is present in 50% to 72% of patients. In patients with unilateral involvement, the opposite thumb is often hypoplastic.

Based on the severity of involvement present on radiograph, radial club hand is classified into one of four types:

Type I: Deficiency of distal radial epiphysis; the appearance of the distal epiphysis is delayed and mild shortening of the radius is present.

Type II: Complete but short radius (hypoplasia); proximal and distal epiphyses are present but the radius is short causing ulna to bow.

Type III: Proximal radius is present; the distal and middle portions are absent and bowing of the radius is maximum in these patients.

Type IV: Complete absence (aplasia); this is the most common presentation. There is no radial anlage with total absence; therefore, the ulna is straight but the wrist is deviated radially.

Etiology

Although environmental insults, irradiation, nutritional deficiencies, and medications have been implicated in radial club hand, the definite mechanism remains unknown. Hereditary tendencies are seen in patients with Holt-Oram syndrome, Fanconi’s anemia, and thrombocytopenia absent radius (TAR) syndrome. After a thorough clinical examination, most children should have genetic screening.

Clinical Features

Hand
In types III and IV radial club hand, the carpi articulate with the ulna and there is no radiocarpal joint. The soft tissue on the radial side is hypoplastic and functions as a tether. The thumb involvement varies from an absent thumb to a floating thumb (pouce flottant) to a hypoplastic thumb; rarely is a normal thumb present. The digits are often stiff at interphalangeal joints with a radial inclination. The radial digits are severely involved. Camptodactyly and decreased flexion of radial digits (especially in the index finger) are common. The quality of index finger mobility may alter the choice for pollicization in a child with thumb aplasia.

Forearm
The ulna is almost 60% shorter than its normal length and is often bowed. The ulna appears to be broad on radiograph. The elbow may have an extension contracture that can be improved with manipulation and splinting. If the elbow contracture cannot be improved, then centralization or radialization cannot be performed. Elbow flexion to allow hand to mouth activity is required before correction of the radial club hand. It is recommended to allow persistent deformity with radial deviation, which will be more functional in the presence of a stiff elbow.

Muscle and nerve involvement
The muscles of the upper extremity may be hypoplastic or absent. The most commonly involved muscles include the pectoralis major, biceps, brachioradialis, supinator, wrist radial extensors, flexor carpi radialis, and thumb muscles. Residual fibrous anlage of radius is present in type III radial club hand. The median nerve often supplies the radial nerve territory and is duplicated in 25% of patients. The radial artery is often absent, and the ulnar artery is the major vessel for the hand. The interosseous arteries are well developed and may substitute for the radial artery.

Associated Anomalies

VACTERL/VATER anomalies
VACTERL is an acronym for vertebral, anorectal, cardiac, tracheo-esophageal, renal, and limb anomalies.

Holt-Oram syndrome
Radial club hand associated with cardiac anomalies is termed Holt-Oram syndrome. This autosomal dominant inherited disorder accounts for 10% to 13% of patients. Affected patients have triphalangeal thumbs, proximal radioulnar synostosis, and proximal humeral defects along with cardiac anomalies (e.g., atrial septal defect, ventricular septal defect, tetralogy of Fallot, mitral valve prolapse, or patent ductus arteriosus). Hereditary tendencies are often present in patients with Holt-Oram syndrome; therefore, the family should have genetic counseling.

TAR syndrome
Thrombocytopenia with absent radius syndrome is an autosomal recessive disorder that commonly has bilateral involvement. Thrombocytopenia is present at birth but corrects itself over time; the survivorship is good. In TAR syndrome, the knee is abnormal in 50% of patients. Patients with TAR syndrome commonly have type IV involvement and the thumb is often present.

Fanconi’s anemia
Fanconi’s anemia is an autosomal dominant disorder that presents with progressive pancytopenia associated with an increased risk of malignancies. The thumb is normally present. The pancytopenia is often diagnosed in the first decade of life. Children with Fanconi’s anemia do not survive to adulthood, and there is a 25% risk of having another child with the disease.

Management

At birth:

• Management of cardiac anomalies, if present.
  
  
• Rule out associated anomalies: Radiograph of the entire spine, blood work including platelet counts, 2-D echocardiography, and ultrasound of kidneys to rule out associated renal anomalies. Cardiac and renal anomalies are common with congenital skeletal defects because the heart, kidneys, and musculoskeletal system are mesodermal in origin and any insult in first trimester organogenesis may affect these systems.
  
  
• Recommend genetic evaluation and family counseling, especially in patients with Fanconi’s anemia.
  
  
• Use manipulation, stretching, and serial casting/splinting. Parents are taught stretching of the contracted radial structures.
  
  
• Use manipulation and serial casting of the elbow extension contracture.

Six-12 months:

• Splinting. An ulnar-based splint with Velcro straps provides viscoelastic stretching of the radial anlage, which may require operative release. A mobile carpus is less likely to require carpectomy during centralization and puts less pressure on the growing ulnar epiphysis.
• Soft tissue distraction. This is recommended by some surgeons before centralization or radialization to stretch the tight radial structures. Soft tissue distraction along with release of the fibrotic radial anlage allows easier placement of the carpus over the distal radius.
• Centralization/radialization of carpus on ulnar epiphysis. This procedure involves positioning the radially subluxed carpus over the ulna so that it is aligned along the long axis of the ulna (third metacarpal is in line with the ulna). Due to the tight radial structure, a notch in the carpus is often made by excising a portion of the proximal carpal row. The distal end of the ulna is positioned in the notch prepared after carpectomy with the forearm in neutral. An intramedullary K-wire is used to maintain the construct. Some surgeons remove the K-wire after 4 to 6 weeks to allow some motion at the wrist joint, while other surgeons leave the K-wire in forever. Occasionally, minimal shaving of the broadened ulna is required. This must be done carefully to avoid injury to the growth plate. Premature closure of the growth plate is a well-documented complication.

Centralization is often combined with tendon transfers. The radial wrist motors are transferred to the ulnar side, which provides dynamic correction. If the ulna is bowed significantly (more than 30%), then an ulnar osteotomy may be performed. The osteotomy straightens the arm, is cosmetically appealing, and is mechanically advantageous for the tendons.

The limb is predestined to be shorter (40% of normal limb), and this may be accentuated if the ulnar epiphysis is damaged. A planned distraction lengthening may be performed when a patient is between 6 and 8 years old. A small amount of length may also be gained by positioning the carpus at the end of the ulna without creating a notch and by preoperative soft tissue distraction.

Buck-Gramcko described radialization as a superior alternative to centralization. In this procedure, the ulna is placed in line with the second metacarpal. The radial wrist extensors and flexors are transferred to the ulnar side, which is mechanically advantageous. This procedure avoids resection of carpus, which helps increase the total arm length. Although principally sound, radialization is not easy because the tight radial structures make it difficult for the ulna to be aligned to the second metacarpal.

• Pollicization. This procedure entails creating a thumb out of the fingers, usually the index finger. The index finger is osteotomized and shortened at the metacarpal base and rotated to position it in opposition to the fingers. Pollicization is indicated in cases with absent or rudimentary thumbs. Brain imprinting of thumb is ongoing up to age 2 to 3 years, so pollicization should be performed before that time. Scissoring adaptation persists if thumb creation is delayed. If the thumb has reasonable skeletal and joint structure, then tendon transfers and ligament reconstructions may suffice to build a usable thumb. Rebuilt thumbs often require a distraction lengthening at a later date.
• Arthrodesis. Wrist arthrodesis is usually reserved for patients who are close to skeletal maturity or those with recurrence.
• Forearm lengthening. Generally, the forearm is 50% to 60% shorter than the normal forearm after wrist stabilization procedures. Ilizarov principles of distraction osteogenesis are used to lengthen the forearm in a staged manner. Forearm lengthening is, however, associated with many complications. Most of the complications are minor, but some major complications include finger stiffness, nerve injury, pin tract infections, and recurrence of deformity.

Results

Generally, the results of wrist stabilization procedures are advantageous. No true outcome studies are available, and the decision to proceed with staged reconstruction is individualized.

Bibliography

Bora FW Jr, Osterman AL, Kaneda RR, Esterhai J. Radial club-hand deformity. Long-term follow-up. J Bone Joint Surg Am. 1981; 63:741-745.

Buck-Gramcko D. Radialization as a new treatment for radial club hand. J Hand Surg Am. 1985; 10:964-968.

Kessler I. Centralisation of the radial club hand by gradual distraction. J Hand Surg Br. 1989; 14:37-42.

Manske PR, McCaroll HR Jr. Index finger pollicization for a congenitally absent or nonfunctioning thumb. J Hand Surg Am. 1985; 10:606-613.

Raimondo RA, Skaggs DL, Rosenwasser MP, Dick HM. Lengthening of pediatric forearm deformities using the Ilizarov technique: Functional and cosmetic results. J Hand Surg Am. 1999; 24:331-338.