Upper Extremity Problems In OI: Think Function Or Cosmesis.

W.G. Cole
Division of Orthopaedics, The Hospital for Sick Children, Toronto, Canada

Fractures and deformities of the upper extremity are common and are often troublesome. The problems in the mild form of osteogenesis imperfecta type IA (OI-IA) and in the severer forms will be considered separately.

Osteogenesis imperfecta type IA:

There are two fracture categories in children with OI-IA. The first category includes children with standard fractures that occur as a result of falls and related injuries. The second category includes children with avulsion fractures that occur from sudden muscle contractions.

Children in the first category show similar patterns of fractures to normal children. The fractures are treated using standard manipulative and operative techniques. Light weight casts and early mobilization are used to minimize disuse osteoporosis. Care is taken to achieve and maintain anatomical or nearly anatomical positions of the fractures in order to minimize the likelihood of malunions and recurrent fractures. Particular care is needed in treating fractures that produce minimal external callus as they have a high incidence of refracture, particularly if there is an angular deformity. A removable forearm orthosis can be useful to protect the arm while the bones are consolidating. Recurrent fractures, particularly of the shafts of the radius and ulna, usually require deformity correction and intramedullary titanium rodding. The medullary cavity often needs to be reamed to accomodate the rod.

Children in the second category usually have avulsion fractures of the olecranon. Some children are first diagnosed with OI-IA after presenting with such a fracture. Olecranon fractures are usually displaced and need to be operatively reduced and internally fixed. While stainless steel tension band wiring is the usual technique the children usually need a second operation to remove prominent wires. An alternative is to use a biodegradable tension band technique that uses heavy polyglycolic acid sutures and rods. Biodegradable rods can also be other used for some of the standard fractures such as fractures of the lateral condyle of the humerus.

Severe types of osteogenesis imperfecta:

Many children in this group have osteogenesis imperfecta due to dominant-negative mutations of the COL1A1 or COL1A2 genes of type I collagen. A few have osteogenesis imperfecta type V due to mutations in other gene loci.

Progressive deformities and recurrent fractures are common in the severer forms of OI. The deformities consist of varus deformities of the proximal and distal humerus and bowing of the forearms. These deformities appear to result from a combination of gradual deformation and malunited fractures. The deformities often accelerate in severity in children using manual wheel chairs. Hand fractures are relatively uncommon.

Fractures are treated by standard methods. If there is no detectable fracture on the radiographs, the child is treated as having a fracture as light weight casts and slings provide pain relief. Fractures of the proximal humerus and humeral shaft are usually treated with a collar and cuff arm support and a light weight half cast. Angular deformities need to be avoided as recurrent fractures may otherwise follow. Operative correction of persistent angular deformities and recurrent fractures consists of one or more osteotomies to align the humerus and internal splinting using a William's stainless steel rod or a titanium elastic rod. In contrast to the Williams rods, the titanium rods can be introduced without perforating the growth plate or epiphysis. The titanium rods may also produce less stress shielding of the bone than the more rigid Williams rod.

Fractures of the radius and ulna are often difficult to treat because of their tendency to malunion and refracture. Incompletely healed fractures of the distal radius and ulna can be supported by a removable forearm orthosis while the bone consolidates. Fractures of the shafts of the radius and ulna may be treated similarly. However, titanium rodding of the radius and ulna is useful in children with persistent deformities and recurring fractures and in older children and adolescents with fresh fractures of the shafts of the radius and ulna. The titanium rods are more flexible than the stainless steel Williams rods.

Summary:

Fractures and deformities of the humerus, radius and ulna are common. Many fractures can be successfully treated without surgery. However, operative treatment is required when fractures involve the growth plates and joint surfaces and for increasing deformities and recurrent fractures. The emphasis of treatment is on the preservation and enhancement of function and appearance.

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Reference: Proceedings of the 7th International Conference on Osteogenesis Imperfecta. Montreal, Canada, 1999.