Slotted intramedullary hip screw nails reduce proximal mechanical unloading.

The current prospective and randomized study was done to determine whether fixation of intertrochanteric femoral fractures that lack a medial buttress with a dynamically locked intramedullary hip screw prevents proximal stress shielding. Stress shielding was evident by the presence of cortical hypertrophy at the level of the tip of the nail and often was associated with midthigh pain. Of the 80 patients enrolled in this trial, 64 still were alive after 1 year. Among these patients, 30 had the nail classically locked with two screws transfixing the nail in two separate holes (Group A), and 34 had the nail locked with one screw passing through a slot (Group B). The average duration of followup was 37 months (range, 12-49 months). Tolerance to dynamically locked nails was significantly better, with only one patient in Group B having cortical hypertrophy of the femur at the level of the tip of the nail, compared with six patients in Group A. Other outcomes were equal in both groups. Late tolerance to this new dynamically locked intramedullary hip screw is good, while retaining the known advantages of nailing of these fractures.