A mild, and probably distinct form of Hunter’s syndrome has been recognized in which there are much less severe bone and joint deformities, no significant mental retardation and longevity compatible with life up to 50 years.
The child may present first to he orthopaedic surgeon in mid-childhood with knock-knee deformity. Clinical examination shows limited movements at the hips, knees, elbows and shoulders and, short fingers with limited flexion but no spine deformity and little or no decrease in height.
Visceral changes are also minimal and there are no corneal opacities. Excretion of abnormal amounts of heparan sulphate and dermatan sulphate in the urine is the same as in mucopolysaccharidosis II-A and the same enzyme defect is found. The condition is thought to be an allelic variant.
Radiological Appearances
The radiological appearances, though mild, are typical of a mucopolysaccharidosis. The ribs are short, wide and paddle-shaped and the vertebral bodies show anterior prominence, particularly at the lower border. The pelvis shows a slight hour-glass appearance but the hips are normal.
The hands show the most clear changes, with thickened metacarpals with square bases, and small, mildly deformed phalanges which are cone-shaped.
Treatment
Genu valgum may require correction by epiphysial stapling or supracondylar osteotomy. If an eqiuus deformity is present elongation of tendocalcaneus helps.
Limitation of movements in the joints of the upper limb is not usually sufficiently disabling to need treatment.
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