Fractures of the shaft of the humerus are most frequently caused by (1) direct trauma that results in a transverse, oblique, or com-minuted fracture, or (2) an indirect twisting force that results in a spiral fracture. The nerves and brachial blood vessels may be in-jured with these fractures. Wrist drop is indicative of radial nerve injury. Initial neurovascular assessment is essential to identify nerve or blood vessel injury, which requires immediate attention.
Initially, well-padded splints, overwrapped with an elastic bandage, are used to immobilize the upper arm and to support the arm in 90 degrees of flexion at the elbow. A sling or collar and cuff support the forearm. The weight of the hanging arm and splints reduce the fracture. External fixators are used to treat open fractures of the humeral shaft. Open reduction with internal fix-ation of a fracture of the humerus is necessary with nerve palsy, blood vessel damage, comminuted fracture, or pathologic fracture.
Functional bracing is another form of treatment used for these fractures. A contoured thermoplastic sleeve is secured in place with interlocking fabric (Velcro) closures around the upper arm, immobilizing the reduced fracture. As swelling decreases, the sleeve is tightened, and uniform pressure and stability are applied to the fracture. The forearm is supported with a collar and cuff sling (Fig. 69-8). Functional bracing allows active use of muscles, shoulder and elbow motion, and good approxima-tion of fracture fragments. Pendulum shoulder exercises are performed as prescribed to provide active movement of the shoulder, thereby preventing adhesions of the shoulder joint capsule. Isometric exercises may be prescribed to prevent mus-cle atrophy. The callus that develops is substantial, and the sleeve can be discontinued in about 8 weeks. Complications that are seen with humeral shaft fractures include delayed union and nonunion.