Complications with dog humeral shaft fractures

The most common complications in humeral shaft fracture are:

• Implant loosening/implant failure
• Radial nerve neurapraxia
• Malalignment with malunion
• Osteomyelitis

Due to the presence of the supratrochlear foramen, stable nail fixation in the metaphysis is difficult, which leads to a higher incidence of nail loosening.

Interlocking nails (ILN) cannot be positioned to the lower end of the humerus due to the presence of the supratrochlear foramen. ILN are hence only a stable fixation method for more proximal humeral fractures. Using ILN for more distal fractures can lead to implant instability.

There is less bone stock for plate fixation in the distal area of the humerus. Implant loosening can occur if less than three screws can stably be placed in the distal fragment or when a smaller plate is used.

The radial nerve crosses the humerus in the mid/distal shaft area. Fractures in this area can induce radial nerve neurapraxia. When using a lateral approach, the radial nerve must be identified, mobilized, and retracted during reduction and plate fixation. There is a high risk of damaging the radial nerve if it is not identified and protected.

Malalignment can occur due to limited visibility of the whole bone (brachialis muscle covering the bone) and inadequate plate contouring due to the irregular shape of the humerus. Alignment is always more complicated with comminuted fractures.

In the presence of an open fracture or iatrogenic contamination, osteomyelitis can occur in the humerus, especially if there is instability at the fracture site or extensive soft tissue trauma.