RADIAL DYSPLASIA – Kids Orthopedic
ABOUT THE DISEASE
Radial dysplasia, also known as radial
club hand or radial longitudinal deficiency, is a congenital difference occurring in a longitudinal direction
resulting in radial deviation of the wrist and shortening of the forearm. It can occur in different ways, from a minor
anomaly to complete absence of the radius, radial side of the carpal bones and thumb.
Hypoplasia of the distal humerus may be present as well and can lead to stiffness of the elbow. Radial deviation of the wrist is caused by lack of
support to the carpus, the radial deviation may be reinforced if forearm muscles are functioning poorly or have abnormal insertions.
The incidence is between 1:30,000 and 1:100,000 and it is more often a
sporadic mutation rather than an inherited condition. In case of an inherited condition, several syndromes are known for an association with radial dysplasia, such as the cardiovascular Holt-Oram syndrome, the
gastrointestinal VATER syndrome and the hematologic Fanconi anaemia and TAR syndrome.
Other possible causes are an injury to the apical ectodermal ridge during upper limb development, intrauterine compression, or maternal drug use (thalidomide).
TYPES OF ABNORMALITIES
Bone And Joint Abnormalities Clinical Features Of Radial Deficiency (Types II, III, And IV; See Presentation, Classification) Are Dramatic, With Abnormalities Of The Entire Extremity. The Scapula Is Often Small, And The Clavicle Is Often Shorter, With An
Increased Curvature. The Humerus May Or May Not Be Short, And Deficiencies Of The Capitellum And Trochlea Are Common. Elbow Motion Is Usually Diminished More In Flexion Than In Extension.
The forearm is always decreased in length, and the ulna is approximately
60% of the normal length at the time of birth. This discrepancy persists throughout the growth period and into adulthood. True forearm rotation is absent in patients with partial or complete aplasia of the radius.
Muscle and tendon abnormalities Numerous muscular abnormalities are found throughout the upper extremity. The deltoid or the pectoralis major can be hypoplastic, can be partially absent, or can have an abnormal insertion. The biceps may be
absent or fused to the underlying brachialis.
The forearm demonstrates the most severe abnormalities, which may involve any of the muscles that originate from or attach to the radius, including the
following: Extensor carpi radialis longus
Extensor carpi radialis brevis Pronator teres Flexor carpi radialis
Palmaris longus Flexor pollicis longus Pronator quadratus
Supinator
Nerve and artery abnormalities The radial nerve usually terminates at the elbow, and the ulnar nerve is normal. An enlarged median nerve substitutes for the absence of the radial nerve and supplies a dorsal branch for dorsoradial sensibility. This
subcutaneous branch is positioned in the fold between the wrist and forearm and must be protected during surgery.
The vascular anatomy demonstrates a normal brachial and ulnar artery. The radial artery is often absent, and the interosseous arteries usually remain patent.
Associated abnormalities Radial deficiency is associated with numerous systemic conditions, including Holt-Oram syndrome (cardiac septal defects); TAR syndrome; Fanconi anemia (aplastic anemia); and VACTERL syndrome. In addition to these conditions, a variety of associated musculoskeletal deformities
appear sporadically. These include cleft palate, clubfoot, kyphosis, scoliosis, torticollis, and rib deformities.
Classification of radial dysplasia is practised through different models. Some
only include the different deformities or absences of the radius, where others also include anomalies of the thumb and carpal bones. The Bayne and Klug classification discriminates four different types of radial dysplasia.
A fifth type was added by Goldfarb et al. describing a radial dysplasia with the participation of the humerus. In this classification, only anomalies of the radius and the humerus are taken into consideration.
James and colleagues expanded this classification by including deficiencies of the carpal bones with a normal distal radius length as type 0 and isolated thumb anomalies as type N. Type N: Isolated thumb anomaly Type 0: Deficiency of the carpal bones
Type I: Short distal radius Type II: Hypoplastic radius in miniature Type III: Absent distal radius
Type IV: Complete absent radius Type V: Complete absent radius and manifestations in the proximal
humerus
Treatment
Splinting And Stretching In cases of a minor deviation of the wrist, treatment by splinting and stretching alone may be a sufficient approach in treating the radial deviation in RD. Besides that, the parent can support this treatment by
performing passive exercises of the hand. This will help to stretch the wrist and also possibly correct any extension contracture of the elbow. Furthermore, splinting is used as a postoperative measure trying to
avoid a relapse of the radial deviation.
Centralization More severe types (Bayne type III en IV) of radial dysplasia can be treated with surgical intervention. The main goal of centralization is to increase hand function by positioning the hand over the distal ulna and stabilizing
the wrist in a straight position. Splinting or soft-tissue distraction may be used preceding the centralization.
In classic centralization, central portions of the carpus are removed to create a notch for placement of the ulna. A different approach is to place the
metacarpal of the middle finger in line with the ulna with a fixation pin.
Radialization Buck-Gramcko described another operation technique, for treatment of radial dysplasia, which is called radicalization. During realization the
metacarpal of the index finger is pinned onto the ulna and radial wrist extensors are attached to the ulnar side of the wrist, causing overcorrection or ulnar deviation. This overcorrection is believed to make relapse of radial
deviation less likely.
Recovery The child has to perform stretching, splinting, and similar therapeutic
exercises for a specific period of time, if the doctor decides to treat his radical club hand non-surgically. However, the orthopaedic must examine the child’s hand consistently to assess the effectiveness of the
treatment plan.
On the other hand, the recovery period will differ if the orthopaedic has to perform surgery. Also, the surgery and post-operative care will vary according to the type of radical club hand. However, the orthopaedic will
perform the surgery in phases and only after the child attains a specific age.
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