: 1513 : 253–256  Various forms of osteoporosis, such as iatrogenic osteoporosis, idiopathic juvenile osteoporosis, disuse osteoporosis and exercise-related osteoporosis should also be considered as explanations when OI is suspected. : 255–256

Treatment
There is no cure for osteogenesis imperfecta. Maintaining a healthy lifestyle by exercising and avoiding smoking can help prevent fractures. Treatment may include care of broken bones, pain medication, physical therapy, mobility aids such as braces or wheelchairs, and surgery.Judging the success or failure of treatment can be difficult in OI patients, as decreased bone fracture rates may just be coincidental. While these rates are often used in medical studies to judge treatment efficacy, a Norwegian study of fifteen people with OI emphasized that they feel doctors should consider the whole patient and not just fracture rates. Acute bone fracture care
Bone fractures are treated in individuals with osteogenesis imperfecta in much the same way as they are treated in the general population—OI bone heals at the same rate as non-OI bone. : 431  A greater emphasis is placed on using lightweight materials to immobilize the fracture, as in moderate or severe types of OI, using heavy casts, such as hip spica casts, can cause fractures at the bones at the boundaries of the cast, as well as generalized osteopenia. : 431  The lightweight cast or splint is then replaced with a removable orthosis after a few weeks and once evidence of union is seen on X-ray.
The cause is genetic mosaicism; that is, some of, or most of, the germ cells of one parent have a dominant form of OI, but not enough of their somatic cells do to cause symptoms or obvious disability in the parent—the parents different cells have two (or more) sets of slightly different DNA. : 1513  It has been clinically observed that ≈5–10% of cases of OI types II and III are attributable to genetic mosaicism. : 532

Pathophysiology
People with OI are either born with defective connective tissue, born without the ability to make it in sufficient quantities, or, in the rarest genetic types, born with deficiencies in other aspects of bone formation such as chaperone proteins, the Wnt signaling pathway, the BRIL protein, et cetera. In type I the collagens structure itself is normal, it is just its quantity that is low. : 1516  Types II, III and IV are usually, but not always, related to a deficiency of type I collagen. One possible deficiency arises from an amino acid substitution of glycine to a bulkier amino acid, such as alanine, in the collagen proteins triple helix structure. The larger amino acid side-chains lead to steric effects that creates a bulge in the collagen complex, which in turn influences both the molecular nanomechanics and the interaction between molecules, which are both compromised. Depending on both the location of the substitution and the amino acid being used instead, different effects are seen which account for the type diversity in OI despite the same two collagen genes being responsible for most cases.