The Orthopaedic Manifestations of Pseudoachondroplasia

The Orthopaedic Manifestations of Pseudoachondroplasia

Guirguis James; Weiner Dennis S

Pediatrics; Evanston

2019

2019-08

In 1959, Maroteaux and Lamy initially designated pseudoachondroplasia as a distinct dysplasia different from achondroplasia, which is the most common form of skeletal dysplasia associated with dwarfism. Pseudoachondroplasia is the second-most common form of skeletal dysplasia. Pseudoachondroplasia is caused by a mutation in the COMP gene on chromosome 19p13.1-p12 encoding the cartilage oligomeric matrix protein. The mutation causes an accumulation of mutated COMP protein within the rough endoplastic reticulum of chondrocytes leading to premature chondrocyte apoptosis. This cascade of molecular events eventually results in rendering the articular cartilage and growth plate cartilage incapable of withstanding routine biomechanical loads with resultant deformity of the joints, particularly in the lower extremities. A unique opportunity to review charts and radiographs of 141 patients with pseudoachondroplasia allowed the author to assemble the typical findings in pseudoachondroplasia. This cohort, to our knowledge, represents the largest group of patients describing the typical orthopaedic manifestations of pseudoachondroplasia. The intensive review of this cohort yielded the following clinical and radiographic information: Patients with pseudoachondroplasia have a normal craniofacial appearance and are of normal intelligence. Short stature is not present at birth and generally appears by 2 to 4 years of age. The condition is a form of spondyloepiphyseal dysplasia and the long bones are characterized by dysplastic changes in the epiphysis, metaphysis, and vertebral bodies. The hands have short, stubby fingers, short metacarpals, lax wrists, diminished extension of the elbow, and limitation of shoulder motion. Occasionally odontoid dysplasia is seen with kyphosis, scoliosis, and lumbar lordosis, commonly. The gait is characterized by "waddling". The knees show either genu valgum, genu varum, or "windswept" deformity and the feet and ankles are in pronovalgus position with short, wide feet. Radiographically the long bones have altered appearance and structure of the epiphyses with small irregularly formed or fragmented epiphyses or flattening. The metaphyseal regions of the long bones show flaring, widening, or "trumpeting". The cervical vertebrae show platyspondyly. The thoracic and lumbar vertebrae show either platyspondyly, ovoid, "cod-fish" deformity, or anterior "beaking". Most commonly these distortions of the long bones and the axial skeleton, lead to premature arthritis particularly of the hips and often the knees not uncommonly in the 20- to 30-year-old age group. Vertebral "beaking" (Image 1) Epimetaphyseal dysplasia (Image 2)

Achondroplasia; Apoptosis; Arthritis; Biomechanics; Bone (axial); Bone dysplasia; Bones; Cartilage; Cartilage (articular); Cartilage oligomeric matrix protein; Chondrocytes; Chromosome 19; Chromosomes; Dwarfism; Dysplasia; Elbow; Elbow (anatomy); Epiphysis; Extremities; Feet; Gait; Hand (anatomy); Hip; Intelligence; Joint diseases; Knee (anatomy); Kyphosis; Medical Sciences--Pediatrics; Mutation; Orthopedics; Plates (structural members); Proteins; Radiographs; Radiography; Skeleton; Thorax; Vertebra; Vertebrae

October 2019 Update

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

1-1

144

NEOMED College of Medicine

NEOMED Student Publications