Session VI - Geriatrics

How to Prevent Fixation Failure in Patients with an Osteoporotic Trochanteric Fracture Treated with Dynamic Hip Screw: A Prospective Randomized Study

Antonio Moroni, MD; Cesare Faldini, MD; Francesco Pegreffi, MD; Sandro Giannini, MD; Rizzoli Orthopaedic Institute, University of Bologna, Bologna, Italy

Purpose: Dynamic hip screw (DHS) fixation is widely used for patients with trochanteric fractures. Significant failure rates have been reported among osteoporotic patients because of lag screw cutout resulting >from inadequate fixation. Recently, studies have shown that fixation can be improved with use of hydroxyapatite- (HA) coated AO/ASIF screws. Our purpose was to determine whether similar results could be achieved for patients with osteoporotic trochanteric fractures.

Methods: One hundred and twenty patients with trochanteric fractures were selected. Patients were divided into two groups and randomized to receive 135° 4-hole DHS with either standard lag and cortical AO/ASIF screws (group A) or HA-coated lag and cortical AO/ASIF screws (group B). Included were women age 65 or older, with AO type A1 or A2, and bone mineral density (BMD) lower than -2.5 T score. Patients were excluded if the lag screw extended into the proximal third of the femoral head.

Results: Patient age, BMD, and lag screw position in the femoral head did not differ between groups. In group A there were four patients with cutout and none in group B (P<0.05;_ _ = 0.8). Three patients with cutout underwent revision with a bipolar prosthesis; the fourth patient with a lag screw cutout refused revision. Fracture impaction was 13 ± 15 mm in group A and 10 ± 7 mm in group B, and the average tip apex distance (TAD) was 22 ± 4 mm in group A and 23 ± 5 mm in group B, which were not significant. No differences in the percentages indicating "at risk" (TAD _ 25 mm) or "not at risk" (TAD _ 25 mm) for cutout were found between the two groups. In both the standard and HA-coated group, no patient with a TAD _ 25 mm experienced cutout. In the standard group, patients experiencing cutout all had a TAD greater than 25 mm. However, no patients in the HA-coated screw group with a TAD greater than 25 mm experienced cutout. At 6 months, the Harris Hip Score was 63 ± 22 (group A) and 71 ± 18 (group B) (P = 0.02); The SF-36 score was 56 ± 24 (group A) and 62 ± 19 (group B), which was not significantly different. Postoperative neck-shaft angle was 134 ± 5° in group A and 134 ± 7° in group B, but, at the 6-month follow-up, it was 129 ± 7° (group A) and 133 ± 7° (group B) (P = 0.008).

Discussion: HA-coated AO/ASIF screws optimize DHS fixation and clinical outcome of patients with osteoporotic trochanteric fractures. These superior clinical results suggest that HA-coated implants could be the key to improving fixation in mechanically weak bone.