Osteogenesis imperfecta has the triad of fragile bones, blue sclerae, and early deafness. OI was once divided into “congenita,” the forms detectable at birth, and “tarda,” the forms detectable later in childhood; this did not account for the variability of OI.

The Sillence classification divides OI into four types based on clinical and radiographic criteria. Additional types have been proposed based on histologic distinctions.

Osteogenesis Imperfecta Type I (Mild):

This form is sufficiently mild that it is often found in large pedigrees. Many type I families have blue sclerae, recurrent fractures in childhood, and presenile hearing loss (30–60%). Both types I and IV are divided into A and B subtypes, depending on the absence (A) or presence (B) of dentinogenesis imperfecta. Other possible connective tissue abnormalities include easy bruising, joint laxity, and mild short stature compared with family members. Fractures result from mild to moderate trauma and decrease after puberty.

Osteogenesis Imperfecta Type II (Perinatal Lethal):

These infants may be stillborn or die in the 1st yr of life. Birthweight and length are small for gestational age. There is extreme fragility of the skeleton and other connective tissues. There are Continue reading »

Popliteal cysts (Baker cyst) are commonly seen in children and are different than in adults. They are cystic masses filled with gelatinous material that develop in the popliteal fossa, are usually asymptomatic, and are not related to intra-articular pathology. Spontaneous resolution usually occurs, although the process can take several years.

Clinical Presentation:

The usual presentation is that of a mass behind the knee that may be fairly large when first noted. There are usually no symptoms of internal derangement of the knee. Physical examination reveals a firm mass in the popliteal fossa, often medially located and usually distal to the popliteal crease. The mass is most prominent when the knee is extended and the patient is lying in prone position.

The most common site of origin is the bursa of the gastrocnemius and semimembranosus. Another common site of origin is a herniation through the posterior joint capsule of the knee. Histologically, the cysts are classified as fibrous, synovial, inflammatory, or transitional.

Diagnosis:

Transillumination of the cyst on physical examination is a simple diagnostic test. Knee Continue reading »