They are usually associated with low energy trauma such as jumping, and mainly affect patients younger than 1 year of age with a peak at 4 months of age. Lateral condylar fractures occur more frequently than medial or bicondylar fractures due to anatomic and biomechanical differences. The fracture lines in humeral condylar fractures always extend through the joint surface and then through one or both epicondyles or epicondylar crests, or even into the distal shaft. Lateral/Bicondylar Humeral Condylar Fractures Restrictions are usually in place for 4 weeks, but with uncomplicated healing, the function outcome of these fractures is usually very good. With appropriate owners and post-operative restrictions, external coaptation is not required. These fractures may result in premature closure and shortening of the bone or bowing if closure is asymmetric. Salter-Harris type V or VI fractures have also been reported in the proximal humeral physis. In animals at or near skeletal maturity, a wider variety of fixation devices, including lag screws and tension band wires, can be used to provide additional stability. These are placed in parallel fashion if further growth is expected to minimize compression and allow for continued physeal growth. If the two fragments (the humeral head and the greater tubercle) are still together, adequate stabilization is achieved using two pins from the proximal aspect of the greater tubercle into the humeral neck or the proximal diaphysis. Reduction is aided by placing the shoulder in extension. Little additional dissection is usually required because these frequently separate during the initial injury. The most useful approach for these fractures is a combined approach to the craniolateral region of the shoulder joint and the proximal humerus. The humeral head or the greater tubercle can separate independently, but more commonly the two epiphyses can stay confluent. Parallel pins may be inappropriate in some situations as discussed below.įractures of the humeral head are usually Salter-Harris type I and II. Mechanically, the forces applied to parallel pins are distributed equally between the pins, while with divergent pins, uneven distribution of loads between the implants renders the technique weaker and predisposes the repair to failure. Parallel pins allow for continued physeal growth, while divergent pins may create a locking effect on the physis, resulting in premature closure. Pins placed parallel to each other offer biological and mechanical advantages in comparison to divergent pins. The most commonly used implants for physeal fractures are pins. They should not be in place longer than 4 weeks. In the rare case in which the fracture configuration requires bridging of the physis with of one of these implants, early removal as soon as two weeks after surgery should be considered depending on the degree of healing. Implants that prevent further physeal growth, such as bone plates, lag screws, and external skeletal fixators, should be avoided in the growing animal. It is often presumed that regardless of the implant the physis may close as a result of the inciting or surgical trauma.įixation techniques for physeal fractures should minimally impact blood supply, result in accurate and stable reduction, be easily removable, and not significantly further damage the physis. Physeal fractures occur in immature animals with open physes, usually secondary to trauma, though this may be minimal depending on the affected location. Included will be common fractures and their surgical fixation, the evidence on healing times, and when and if to remove implants. This lecture will focus on the immature dog and fractures specific to them. Books & VINcyclopedia of Diseases (Formerly Associate).VINcyclopedia of Diseases (Formerly Associate).
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