Similarities between Inferior-Center and Center-Center Lag Screw Positions in Femoral Intertrochanteric Fracture Surgeries

Abstract Background: The center-center lag screw position has been widely accepted as the optimal lag screw/helical blade position in femoral intertrochanteric fracture surgery to achieve a tip-apex distance (TAD) less than 25 mm. Despite the inferior-center lag screw/helical blade position having some biomechanical advantages, and the emergence of calcar-referenced tip-apex distance (CalTAD), the clinical differences between the two commonly placed lag screw/helical blade positions remain unclear. This study aimed to (1) report radiological outcomes in managing geriatric femoral intertrochanteric fractures, (2) identify the influences of positions of lag screw/helical blade, and (3) identify the relationship between implants and the values of TAD and CalTAD.Methods: We retrospectively assessed the clinical and radiographic findings of geriatric patients (age ≥ 55 years) who underwent surgery for acute closed femoral intertrochanteric fractures during 1-year period and were followed up a minimum of 6 months. The radiographic parameters and incidences of fixation failure were compared between the different lag screw and helical blade positions (center-center vs. inferior-center). Subgroup analyses of different implant types (extramedullary and intramedullary) were also performed for comparisons for different lag screw positions, and TAD and CalTAD beyond the normal standard value of 25 mm.Results: A total of 206 patients were included during the study period, with a 7.8% fixation failure. There were no differences in incidences of fixation failure between the commonly inserted lag screw/helical blade positions (center-center vs. inferior-center), regardless of the implant types. Those with a TAD > 25 mm had significantly higher incidence of fixation failure than those with a TAD ≤ 25 mm in the extramedullary plate (17.0% vs. 1.2%, p = 0.001), but not in the intramedullary nails (16.1% vs. 4.4%, p = 0.08). There were no significant differences in incidences of fixation failure between CalTAD ≤ 25 mm and CalTAD > 25 mm in either extramedullary or intramedullary implants. Conclusion: Although TAD > 25 mm might increase the fixation failure rate in extramedullary plates, an inferior-center lag screw/helical blade position could achieve comparable radiographic results as a center-center position after osteosynthesis for geriatric femoral intertrochanteric fractures.