To compare the clinical and radiographic results for locked intramedullary (IM) nails and plates used in the treatment of humeral diaphyseal fractures.

Prospective randomization by sealed-envelope technique of eighty-four patients into two study groups: those treated by intramedullary nailing (IMN group; n = 38) and those treated by compression plating (PLT group; n = 46).

Patients admitted consecutively to a university-affiliated Level I trauma center.

All skeletally mature patients admitted to Harborview Medical Center with acute humeral shaft fractures requiring surgical stabilization. Fractures of the diaphysis were defined as being at least three centimeters distal to the surgical neck and at least five centimeters proximal to the olecranon fossa.

Treatment with locking antegrade intramedullary humeral nails (Russell-Taylor design [Smith and Nephew Richards]) or with 4.5-millimeter dynamic compression and limited contact dynamic compression plates (AO design [Synthes]).

Clinical outcome measurements included fracture healing, radial nerve recovery, infection, and elbow and shoulder discomfort. Radiographic measurements included fracture alignment, time to healing, delayed union, and nonunion.

Follow-up averaged thirteen months. Forty-two fractures (93 percent) in the PLT group were healed by sixteen weeks versus thirty-three fractures (87 percent) in the IMN group (p = 0.70). Shoulder pain and a decrement in shoulder range of motion (ROM) were significant associations with IMN (p = 0.007 for both variables) but not with PLT. A decrement in elbow ROM was significantly associated with PLT (p = 0.03), especially for fractures of the distal third of the diaphysis, whereas elbow pain was not (p = 0.123). The sum of other complications demonstrated nearly equal prevalence for both treatment groups.

For patients requiring surgical treatment of a humeral shaft fracture, intramedullary nailing and compression plating both provide predictable methods for achieving fracture stabilization and ultimate healing.