The “double-intra” pertrochanteric femur fracture: An irreducible and redisplaceable fracture pattern

Background Irreducible pertrochanteric femur fractures (PFFs) are associated with a higher risk of mechanical instability and poor clinical outcomes. Awareness of the specific patterns of these irreducible PFFs can help surgeons better prepare for fracture reduction and reduce unnecessary attempts at closed manipulations. This article aimed to introduce a specific subtype of irreducible PFFs, characterized by intramedullary head-neck varus impaction and the anterior fracture line within the joint capsule, termed "double-intra" PFFs. Methods Patients with "double-intra" PFFs treated with cephalomedullary nail between January 2021 and June 2024 were included. Closed reduction was attempted initially, with fracture reduction quality assessed via Chang Reduction Quality Criteria (CRQC); the goal was to achieve "excellent" reduction, defined as anteromedial cortical support (AMCS). If closed reduction failed to meet this standard, a limited open reduction technique (LORT) was used. Bone hooks and 2.5 mm Kirschner wires (K-wires) were used in the LORT to improve the reduction quality. Clinical and radiographic outcomes were utilized to summarize the fracture characteristics and loss of AMCS. The primary goal was assessing the fracture reduction loss in intraoperative fluoroscopies and postoperative 3D-CT images, and the secondary goal was determining the radiographic changes and functional outcomes in the follow-up. Results Twenty-eight patients were retrospectively analyzed. All patients achieved "excellent" reduction before nail insertion; after fixation, 10 patients decreased to "acceptable" and 3 to "poor", leading to a 46.4% reduction loss rate (13/28). Postoperative radiographs showed further AMCS loss in 7/15 patients (46.7%), and overall AMCS achievement rate on postoperative 3D-CT was 28.6% (8/28). Additionally, at 3-month follow-up, the AMCS group had significantly lower △NSA (4.65 ± 1.79 vs. 2.25 ± 1.04, P = 0.002), implant sliding distance (6.65 ± 3.00 vs. 3.75 ± 1.16, P = 0.014), and higher postoperative PPM scores (6.35 ± 1.04 vs. 7.50 ± 1.07, P = 0.018) than the non-AMCS group. Conclusion The "double-intra" pattern is a specific irreducible PFF with difficulty in reduction and proneness to redisplacement perioperatively and postoperatively. Achieving a "double-positive" alignment of the anteromedial cortex and using temporary K-wire fixation as a routine procedure before nailing is essential to prevent reduction loss and improve the likelihood of maintaining the AMCS.