Osteogenesis Imperfecta, X-Ray of child’s arm
shows a fracture with healing that has
resulted in thickening of the bone.
Osteogenesis Imperfecta congenital form in
newborn with lower leg deformity showing tibial arch
Osteogenesis imperfecta (OI) or Brittle Bone Disease
Osteogenesis Imperfecta (OI) is a congenital bone disorder characterized by fragile bones that break very easily, hence the more commonly known name of ‘Brittle Bone Disease’. Osteogenesis imperfecta affects both bone quality and quantity, i.e. bone mass and density(1). This disease is caused by a genetic defect in the body’s ability to make adequate quantities of, or an adequate quality of, the protein collagen usually because of a deficiency of Type-1 Collagen(2).
To understand this disease, it is essential to know a little about collagen. Collagen is one of the predominant proteins in the human body and accounts for about 30% of the body’s total protein content. It acts as a sort of glue or cement that holds everything together. Collagen is found in the connective tissue of ligaments and tendons, the bones, muscles, blood vessels and the corneas of the eyes.
Types of Osteogenesis Imperfecta (O.I.)
The characteristics of Osteogenesis Imperfecta can vary greatly from person to person and the symptoms can also vary from mild to very severe. In 1979, Dr. Sillence from the University of Melbourne, invented a classification system for children with Osteogenesis Imperfecta. Sillence classified four main types of the disease(3) which have been adjusted and added to over the years:-(4,5) The diseases are classified from Type I to type VIII with type I being the most common and mildest form and type II the most severe. The diseases are classified according to several factors including the severity, the quantity and quality of collagen, the severity of the effects on the bones, the eyes and hearing.
Osteogenesis Imperfecta Type V
The two images below show X-Rays of Stage V of the disease, the first in a child and the second in an adult. Stage V is classified as a moderate to severe form of the disease. The Collagen is of sufficient quality but deficient in quantity. There is moderate to severe growth retardation resulting in a shorter stature. The sclera of the eyes can be blue and there is some early hearing loss in some cases.
X-Ray of Type V Osteogenesis Imperfecta in a child
X-Ray showing Type V Osteogenesis Imperfecta in an adult
The most obvious features of type V Osteogenesis Imperfecta, as illustrated in both images above, are abnormally large amounts of repair tissue called hypertrophic calluses in the bones at old fracture sites. These calluses can also occur spontaneously. In microscopic studies the bone cells of Type V have a mesh-like appearance. There is also a characteristic, seen clearly on the first X-Ray above, of the ‘V triad’ which in addition to the hypertrophic calluses, consists of bands next to growth plates and calcification of the membrane between the two forearm bones.
1. Ablin DS, Greenspan A, Reinhart M et-al. Differentiation of child abuse from osteogenesis imperfecta. AJR Am J Roentgenol. 1990;154 (5): 1035-46. AJR Am J Roentgenol (citation) – Pubmed citation
2. Rauch F, Glorieux FH (2004). “Osteogenesis imperfecta”. Lancet 363 (9418): 1377–85. doi:10.1016/S0140-6736(04)16051-0. PMID 15110498.
3. SILLENCE, ALISON SENN, AND D. M. DANKS ‘Genetic heterogeneity in osteogenesis imperfecta’ Journal of Medical Genetics, 1979, 16, 101-116 D. 0. From the Department of Paediatrics and Genetics, University of Melbourne; and the Genetics Research Unit, Royal Children’s Hospital, Victoria, Australia.
4. Wikipedia ‘Osteogenesis imperfecta’ http://creativecommons.org/licenses/by-sa/3.0/
5. Tachdjian’s Pediatric Orthopaedics by John A. Herring,From the Texas Scottish Rite Hospital for Children
5th edition published by Elsevier. ‘Osteogenesis Imperfecta’
6. Osteogenesis Imperfecta Foundation