Short limb dwarfism.
Radiological evaluation of a short limb dwarfism diagnosed as achondroplasia.
The most frequent related generalized short-limb skeletal dysplasias are Achondroplasia ( Ach), Hypochondroplasia and Thanatophoric dysplasia. In all of these dysplasias, there is abnormal endochondral ossification, but periosteal ossification is not affected. These 3 relatively common entities are known to be allelic to the same gene: the fibroblast growth factor receptor 3 gene on chromosome 4p. Heterozygous achondroplasia is the most common nonlethal skeletal dysplasia. The distinctive clinical and radiological features allow a precise diagnosis, as there is little variability in the appearance of affected patients. There is also a very evident molecular homogeneity. On histopathology of the growth plate, there is a quantitative decrease in endochondral ossification. Precise prenatal ultrasonographic diagnosis is possible in the third trimester, and sometimes even in the second. Hypochondroplasia is a relatively common, milder form of achondroplasia, which varies within and between families and lacks the neurological complications often seen in achondroplasia of this group. An accurate prenatal ultrasonographic diagnosis is rare. There are milder changes on histology of the growth plate. Thanatophoric dysplasia is the lethal and most severe dysplasia. It has distinct features (mainly short tubular bones and short ribs with platyspondyly ) allowing a precise radiologic and prenatal ultrasonographic diagnosis. On histopathology of the growth plate, there is disruption of endochondral ossification. Achondroplasia is the most common form of chondrodysplasia in humans. This disorder is inherited as an autosomal dominant trait, though most cases are sporadic. The diagnosis and the differential diagnosis among these various bone dysplasias is largely based on radiographic findings. Achondroplasia is characterized by impaired enchondral ossification which produces typically shortened long bones, spinal abnormalities and a short base of the skull. Growth of long bones is diminushed, the proximal segments being especially affected, so that shortened extremities with bones of normal width result. Rhizomelic shortening is more prominent in the upper extremities. The tubular bones of the hands and feet are similarly affected but to a lesser degree. The deformity of the pelvis is characteristic. Narrowing of the transverse diameter of the sacrum, acetabular hypoplasia and impaired development of the iliac crests, giving a square appearance are typical radiological features. The greater sciatic notch presents as a deep and narrow cleft. In the spine, centers of ossification are abnormally small so that the vertical diameter of the intervertebral spaces may equal that of the ossified vertebrae. As developpment takes place posterior scalloping of the lumbar vertebral bodies in the thoracolumbar area may result in wedging with a consequent thoracolumbar kyphos. Incomplete development of the neural arches causes progressive narrowing of the lumbar canal. This reduction in diameter renders he adult achondroplast peculiarly susceptible to severe and symptomatic disc herniation in later life. Skull enlargment may be caused by hydrocephalus due in turn to a small foramen magnum. The base of the skull is correspondingly shortened. Defective formation of the nasal bones is a common feature. Achondroplasia is clinically recognisable at birth and the radiological findings are specific confirming the diagnosis.
Achondroplasia
From the provided pelvic and spinal X-rays, it can be observed that the transverse diameter of the pelvis is narrowed, with a somewhat “square” shape. The sciatic notch appears elongated and deeply indented. The iliac wings are underdeveloped, showing no significant widening of the upper iliac crest margin. The proximal segment of the femur (especially the proximal femur) is relatively shortened, presenting a clear “delayed” or “slowed” endochondral ossification. In the spine, the lumbar posterior borders show varying degrees of posterior scalloping; underdevelopment of the vertebral arches suggests a tendency toward spinal canal stenosis. The heights of the vertebral bodies do not match the intervertebral spaces proportionally, indicating partial reduction in the vertical height of some vertebrae. The skull base may be shortened (based on clinical history), but due to incomplete cranial imaging data, further assessment is not possible.
Regarding the tubular bones of the limbs, the long bones demonstrate significant shortening, especially in the proximal segments (humerus, femur). This indicates both diaphyseal and cancellous bone developmental anomalies, although overall bone density appears relatively preserved. The distal epiphyses and metaphyses may show mild morphological abnormalities, while joint surfaces appear relatively normal. No obvious fracture lines or distinct signs of soft tissue injury are visible.
Based on the radiographic characteristics and the patient’s history (short-limbed dwarfism, mainly involving the proximal segments), the following diagnoses are considered:
Taking into account the patient’s age (18), clinical presentation (short-limbed dwarfism mainly affecting proximal segments), possible hereditary or genetic background (commonly involving FGFR3 mutations), and the distinctive pelvic morphology with spinal posterior scalloping on X-ray, the most probable diagnosis is: Achondroplasia.
If further genetic confirmation is desired, an FGFR3 genetic test can be conducted.
1. Treatment Strategies:
2. Rehabilitation/Exercise Prescription:
This report provides a reference based on available X-ray images and patient history and does not substitute for in-person consultation or professional medical advice. Patients should return to the hospital for further evaluation or treatment if they have any concerns or if their condition changes.
Achondroplasia
