MR demonstrates cartilaginous megaepiphyses of the hips in Kniest dysplasia of the young child

Orthodontic Treatment in a Patient With Kniest Dysplasia: A Case Study and Review of Literature

Kniest dysplasia is a rare autosomal dominant chondrodysplasia that is characterized by distinct musculoskeletal and craniofacial irregularities. These craniofacial abnormalities include cleft palate, midface anomalies, tracheomalacia, and hearing loss. This article illustrates a case of Kniest dysplasia that presented for orthodontic treatment. The purpose of this literature review is to describe clinical manifestations, radiographic features, histopathological features, genetic mutation, and management of Kniest dysplasia.

Kniest Dysplasia: New Radiographic Features in the Skeleton

Objective

To describe skeletal findings in patients with Kniest dysplasia, focusing on osseous abnormalities that have not been characteristically associated with this disorder.

Materials and Methods

This was a retrospective study. The radiographs of four patients with known Kniest Dysplasia were evaluated by three musculoskeletal radiologists.

Results

Bilateral radial head dislocations and bilateral clubfeet were seen in our series. Other characteristic findings for this dysplasia were seen in all four patients.

Conclusions

Clubfeet and radial head dislocations may be associated with Kniest dysplasia. The presence of these osseous findings in the context of multiple skeletal abnormalities suggestive of a skeletal dysplasia should indicate the possibility of Kniest dysplasia and pathognomonic features for this entity should be sought.

A review of the actual knowledge of the processes governing growth and development of long bones

Autoptic samples of human bones (from 8 weeks of gestation to 12 years of age) and a second group of serial, skeletal x-rays (required for pathologies not related to bone dysplasia in children from 4 months to 17 years of age) provided the material for the analysis of the physes normal growth mechanism presented in this review. Before the appearance of the ossification centers epiphyseal growth rests exclusively on chondrocytes proliferation (interstitial growth), without any detectable differentiated cellular organization. When endochondral ossification starts a defined spatial disposition of chondrocytes and a corresponding organization of the intercellular matrix is set up, so that it is possible to identify a growth vector corresponding to the columns of piled chondrocytes with direction from hypertrophic toward the proliferative cell layers. The complexity of the tubular bones growth process is well represented by the spatial arrangement of the growth vectors. In the late epiphyseal growth another mechanism is active in addition to endochondral ossification, namely, articular cartilage interstitial growth and subchondral remodelling. The knowledge of the normal mode of organization of the physis and its temporal sequence can help to better understand of the deviaton from the normal development of metaphyseal and epiphyseal dysplasias.

Fetal MR imaging of Kniest dysplasia

We present a case of Kniest dysplasia, a rare form of the type II collagenopathies, with prenatal MRI. Sonography revealed only short limbs in the fetus. Fetal MRI findings included enlarged hyaline cartilaginous structures with abnormally high T2 signal intensity, delayed ossification of the pubic and ischial bones, and platyspondyly. By delineating the cartilaginous abnormalities, fetal MRI can contribute to the prenatal diagnosis of chondrodysplasias.

Kniest dysplasia: MR correlation of histologic and radiographic peculiarities

Unossified epiphyses of Kniest dysplasia patients histologically reveal a bizarre pattern of chondrocytes lying amid a highly vacuolated matrix giving rise to the name "Swiss cheese" cartilage. The ossified epiphyses also are unusual in showing clouds of dense punctate calcifications randomly distributed throughout. Both unossified and ossified epiphyses reveal on MR imaging a similar pattern of lakes of bright T2 signal against a relatively normal background, which represents an interesting analogue to the histologic and radiographic features.