Helical Blade Versus Lag Screw Fixation in Cephalomedullary Nailing of Unstable Trochanteric Fractures: A Narrative Review.

Trochanteric (intertrochanteric) hip fractures are among the most common fragility fractures in older adults. Cephalomedullary nailing (CMN) has become the standard treatment strategy for unstable fracture patterns (AO/OTA 31-A2/A3), largely replacing the sliding hip screw (dynamic hip screw, DHS) for this indication. Two proximal fixation designs are in widespread use within CMN systems: the traditional lag screw, which relies on thread engagement in cancellous bone, and the helical blade, which is inserted by impaction, compacting surrounding cancellous bone rather than removing it. This narrative review synthesises the clinical, biomechanical, registry-based, and health-economic evidence comparing helical blade and lag screw fixation. This review also discusses how these findings relate to the wider evidence on implant selection, technical factors influencing fixation success, and complications following CMN, including peri-implant fracture, nonunion, and salvage arthroplasty. Across systematic reviews, meta-analyses, cadaveric biomechanical studies, and large registry cohorts, no consistent superiority of either proximal fixation device has been demonstrated with respect to overall fixation failure, including cut-out. Failure patterns nonetheless differ between implant designs. Medial perforation occurs exclusively with helical blades in the largest single-centre series to report this distinction, while superior migration is more commonly observed with lag screws. Helical blade performance may additionally vary with patient frailty and bone quality. Health-economic evidence continues to favour extramedullary fixation for stable fracture patterns and CMN for unstable fractures. A tip-apex distance greater than 25 mm remains the most reproducible predictor of fixation failure regardless of implant type, while reduction quality and implant positioning are consistently more important determinants of outcome than proximal fixation device selection. Implant choice should therefore be individualised according to patient frailty, bone quality, and surgeon familiarity.