Fracture healing monitored with strain gauges. External fixation of 7 humeral neck fractures.

We measured healing in 7 cases of surgical neck fracture of the humerus by applying a strain gauge measuring bar between the external fixation pins. Repeated measurements provided a healing curve for the individual cases. The gradual decrease in deflection of the fracture zone reached a plateau of about 50 percent after 2 to 4 weeks in 6 cases. Removal of the frame at this time proved safe, as solid healing occurred. In one fracture no such decrease was seen and nonunion developed.