Background: Fixed-angle sliding hip-screw devices are commonly used to treat pertrochanteric fractures. The controlled impaction between the head and neck fragment and the femoral shaft fragment is crucial. However, the poor quality of fracture reduction can intercept controlled impaction and lead to excessive sliding. We hypothesized that excessive sliding occurs when most of the impaction is placed on the fragile posterior cortex of the fracture site.
Methods: This retrospective study included 128 AO/OTA type 31-A1 or 31-A2 fractures treated with fixed-angle sliding hip-screw devices. Cases involving reduced continuity of the anterior cortex at fracture site were defined as Type 1, those involving head and neck fragment anteriorly displaced relative to the femoral shaft fragment as Type 2, and those involving head and neck fragment posteriorly displaced relative to the femoral shaft fragment as Type 3. The extent of postoperative sliding distance of lag screw was measured.
Results: There were 52 cases of Type 1, 30 of Type 2, and 46 of Type 3, with no differences in patient characteristics between types. The mean ± standard deviation extent of sliding for types 1-3 was 4.5 ± 4.9 mm, 7.8 ± 5.6 mm, and 11.1 ± 6.0 mm, respectively (p < 0.0001). Sliding was significantly greater for Type 3 cases than for Type 1 or 2 (p < 0.0001 and p = 0.044, respectively).
Conclusions: Excessive sliding occurs in surgical treatment for pertrochanteric fractures with posterior displacement of the head and neck fragment. In such cases, we recommend appropriate reduction prior to internal fixation.