A 6-month-old boy is found to have bilateral metaphyseal fra

A 6-month-old boy is found to have bilateral metaphyseal fractures of both proximal and distal ends of the tibia. The mother says that her boyfriend takes care of the infant while she is at work. Her boyfriend explains the injuries as the result of multiple falls from bed. Which of the following is the most likely diagnosis?

A. Accidental trauma

B. Physical abuse

C. Osteogenesis imperfecta

D. Osteopetrosis

E. Rickets

Explanation:

The answer is B. There are specific types of traumatic injuries that are virtually pathognomonic of child abuse and can not be explained by accidental trauma (choice A). Metaphyseal fractures are the most typical (although not the most frequent) injuries due to physical abuse. They are produced by pulling and twisting the limbs, which results in traction on the metaphyses transmitted by the joint ligaments. Other skeletal injuries that should suggest abuse include multiple fractures of different ages, and fractures of posterior ribs, scapula, spinous processes, and sternum. The following is a list of injury patterns typically associated with child abuse:

Head injuries: subdural hematoma, diffuse axonal injury, and retinal petechiae. Abdominal injuries: intestinal rupture or hematoma occurs more frequently than injuries to solid organs from a hard blow. Burns: cigarette burns and burns of the buttock area due to scalding water. Osteogenesis imperfecta (choice C) refers to a group of heterogeneous disorders due to inherited deficiencies in synthesis of type I collagen. This condition results in skeletal fragility and numerous fractures starting in utero or early life.

Osteopetrosis (choice D) is a hereditary disease caused by dysfunction in osteoclasts. The bone acquires a stone-like consistency but is also very brittle. Fractures, hydrocephalus, and anemia manifest soon after birth. On x-rays, absence of medullary cavity, sclerosis of bone, and misshapen distal ends of long bones are diagnostic features.

Rickets (choice E) results from deficiency of vitamin D, which is infrequent in industrialized countries. The most typical manifestation of the disease in toddlers is bowing of the legs.