Epiphysis: Small Epiphysis
Several different staging systems of AVN illustrate the imaging features of early vs. advanced disease. DD: Legg-Calvé-Perthes disease (idiopathic), slipped capital femoral epiphysis, sequelae of infection or inflammation, sequelae of trauma.
Epiphysis is small and irregular in contour.
Proximal femoral epiphysis is the most common site (developmental dysplasia of the hip). The epiphysis of the affected side may be smaller.
Osteochondrosis (e.g., osteochondritis dissecans)
Focal disruption of endochondral ossification.
Proportionally decreased growth, osteopenia, course trabeculae in area of field.
Disruption in cell growth from high-dose irradiation.
Fig. 5.49a, b, p. 528
Delayed or smaller multiple ossification centers of the femoral head. No collapse or metaphyseal abnormality.
Symptomless developmental disorder of the hip. Forty to sixty percent are bilateral. Heals completely. May be mistaken for Legg-Calvé-Perthes disease.
Multiple ossification centers may be present in the epiphyses.
Proximal femoral epiphyses may resemble LeggCalvé-Perthes: the growth plates are widened and the epiphyses are prone to slippage due to mechanical instability of the physis.
Multiple epiphyseal dysplasia, Fairbank and Ribbing types
Small irregular epiphyses. Flattened and multi-centric epiphyses at the femoral head.
Most commonly affected locations include the hip, knee, hand, and ankles.
Multiple epiphyseal dysplasia
Fig. 5.27, p. 512
Delay in the appearance of the secondary ossification centers of the long bones, hands, and feet.
May have small, flattened, and fragmented epiphyses. Femoral head epiphyses may develop AVN.
Delayed small and irregular secondary ossification centers.
Hereditary arthro-ophthalmopathy (Stickler syndrome)
All epiphyses are small. Classically, the distal epiphyses are flattened.
Thoracic platyspondyly. Premature OA. Severe myopia and retinal detachment.
Small and irregular epiphyses.
Somewhat flattened and small femoral heads.
Cone epiphyses in the hands and nephronophthisis (medullary cystic kidney disease).
Trichorhinophalangeal syndromes, types I and II
Small flattened proximal femoral epiphyses.
Type II has multiple osteochondromas. Premature OA. Brachyphalangy with deformation of the fingers and wedge-shaped epiphyses.