Genetic disorder leading to skeletal dysplasia.
Kniest-like Dysplasia with Pursed Lips and Ectopia Lentis.
Only three cases reported in the literature.
First described in two siblings, one male and, one female. A second case in a 2-year-old girl was subsequently reported. The mode of inheritance is uncertain, but autosomal recessive or gonadal mosaicism seems most likely.
An iliac bone biopsy reveals markedly abnormal cartilage matrix in certain areas with large clumps of aggregated collagen fibrils. The growth plates are shorter than normal, however, the resultant calcified cartilage and bone trabeculae appear normal. Electron microscopy confirms the presence of broad-banded, aggregated collagen fibers, 10 to 30 times broader than normal that are scattered throughout the cartilage matrix.
Based on the characteristic clinical and radiologic findings. The analysis of bone biopsy specimens reveals the distinctive abnormalities in the cartilage matrix.
Characterized by short stature (<3rd percentile), bowing of the lower extremities with normal or mildly shortened length (upper extremities are normal), talipes equinovarus, stiffness and contractures of several large joints (shoulders, elbows, hips, and knees), and swelling of wrists and knees. Mild craniofacial disproportions with the facial bones being small compared to the skull size and short neck have been described. Other features may include microstomia, pursed lips, high-arched palate, upslanting of the palpebral fissures, bilateral epicanthal folds, ectopia lentis, and myopia. The chest may become bell-shaped with flaring of the lower ribs. Radiologic findings include mainly thoracic platyspondyly and cervical kyphosis with hypoplastic cervical vertebral bodies resulting in decreased neck mobility (extension and rotation), thoracolumbar kyphoscoliosis, pectus carinatum, wide short ribs, an increased lumbosacral angle, bowing and mild shortening of the lower limbs, dumbbell-shaped long bones with short diaphyses, flared metaphyses and metaphyseal sclerosis, delayed ossification of the femoral heads and dysplastic femoral necks, broad and short pelvis with narrow sacrosciatic notches, flattened and hypoplastic acetabular roofs, and wide pubic and ischial bones. Mild brachydactyly may be observed. Unlike Kniest dysplasia, coronal clefts of the vertebrae are absent. Psychomotor development appears normal for age.
Precautions before anesthesia
Preoperative assessment should include careful assessment of the airway to determine the potential for difficult airway management (microstomia, cervical kyphosis, and limitation of neck movements). Radiologic investigation to assess neck stability may be required in the presence of cervical vertebral dysplasia. Anticholinergic premedication to decrease secretions can be of value in the younger age group, particularly if difficult airway management and/or fiberoptic intubation is anticipated. Using lung function tests to assess respiratory function in older patients may be beneficial, although chest deformation seems not to be a constant finding.
Induction of anesthesia must take into consideration the potential for difficult airway management (small mouth, reduced neck mobility). Thus, maintenance of spontaneous ventilation is recommended until the airway has been secured. Alternative airway management options should be immediately available (eg, supraglottic airway device, fiberoptic bronchoscope) and adherence to an established difficult airway algorithm is advised. A surgeon familiar with surgical airway management and the necessary equipment should easily be available in the operating room. Alternatively, an awake fiberoptic intubation should be considered. During anesthesia, the neck should be maintained in a neutral or slightly extended position with adequate neck support at all times. Although not reported as being a problem in infants with this syndrome, respiratory insufficiency following anesthesia may be a potential risk in these children as they become older and the degree of thoracic dystrophy increases. Preoperative assessment and the nature of the surgery should enable the anesthesiologist to determine if postoperative respiratory support will be required. The patient should be positioned carefully with adequate padding and support to all areas due to the fixed deformities in the limbs and neck. Regional anesthesia is not contraindicated, but ...