Orthopedics - Oleksa A.P. 2006

Pathophysiology of Joints
Developmental Defects and Congenital Skeletal Anomalies
Morquio-Brailsford Type (Morquio's disease)

Unlike the previous condition, the disproportionate form of dysostosis enchondralis (dysostosis enchondralis epimetaphysarea) is characterized by disproportionate dwarfism with severe and pronounced impairments in epiphyseal and metaphyseal bone growth in the limbs and spine, along with muscular hypoplasia and joint ligament laxity.

The disorder can be inherited. Morquio described a case where four out of five siblings in the same family were diagnosed with this pathology.

Typically, the disease manifests in children after their first year of life. They begin walking late and subsequently struggle to maintain an upright posture due to progressive deformities. Classic hallmarks of this type of enchondral dysostosis include disproportionate dwarfism accompanied by pronounced deformities of the limbs and trunk (Fig. 62). Limb bones are shorter than normal, and joints are deformed due to both the thickening of the articulating ends and varus or valgus angular deformities of the segments.

The fingers are short, yet unlike in Achondroplasia, they vary in length. Due to flexion contractures in the knee joints and flexion-adduction contractures in the hip joints, as well as truncation of the trunk, the hands may reach down to the knees. Joint stiffness or, conversely, hypermobility is frequently observed. The Sternum is prominently protruding. The rib cage is deformed As a result of a shortened spine caused by pronounced Kyphosis or kyphoscoliosis, with flattening of the vertebrae in the thoracolumbar region. Due to a shortened neck, the shoulder girdles are elevated and inclined forward. In most affected children, the HEAD is of normal size, although dolichocephaly, flattening of the nasal bridge, and similar features may occasionally occur; however, these are not pathognomonic for this type of dysostosis. Corneal clouding is absent. Intelligence in these children is generally normal, although some may lag behind their peers academically. No pathological abnormalities are detected in Internal Organs, systems, or metabolic processes.

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Fig. 62. Disproportionate enchondral dysostosis of the Morquio-Brailsford type in a 13-year-old patient.

Radiological manifestations of the deformities correspond to the clinical findings. The bone epiphyses are misshapen, widened, and flattened, showing varus or valgus deviations (Fig. 63). The metaphyses are also affected, which, alongside epiphyseal involvement, leads to slowed bone growth. Consequently, the diaphyses are shorter and, compared to the norm, sometimes thinner.

The BONES OF THE hand also appear underdeveloped.

The metacarpal and Carpal Bones are smaller and underdeveloped, while the Phalanges are shorter with thickened epimetaphyses. Spinal radiographs reveal deformities of the vertebral bodies. These may present a trapezoidal or wedge-shaped configuration, which accounts for the classic sign of the disease—kyphosis. Generalized platyspondyly with widening of the intervertebral spaces is occasionally observed.

The radiological Structure OF THE vertebrae is indistinct, and their shape is irregular with projections on the anteroinferior margins. Aplasia of one or two vertebral bodies and pseudospondylolisthesis are occasionally detected. Chest radiographs reveal widened and deformed Ribs in their anterior sections.

Fig. 63. Irregular shape of the epiphyses in enchondral dysostosis of the Morquio-Brailsford type in a 13-year-old patient.

As V. A. Sturm (1968) noted, enchondral dysostosis of the Morquio-Brailsford type is regarded as a mild form of gargoylism, occurring without metabolic disturbances or corneal clouding.