Increased Lag-Screw Slide and All-Cause Revision in a New-Generation Cephalomedullary Nail after Treatment of Geriatric Intertrochanteric Femoral Fractures.

Objectives: To compare lag-screw slide and revision surgery rate between two generations of the Stryker Gamma cephalomedullary nail (Stryker, Kalamazoo, MI).

Methods: Design: Retrospective chart review.

Setting: Single academic, Level-1 Trauma Center.

Patient selection criteria: All geriatric patients (65-years and older) who underwent fixation of an intertrochanteric femoral fracture (AO/OTA type 31A1/2/3) by a single surgeon with the Stryker Gamma System from 2020-2024 with at least 3-month follow-up. The Gamma3 system was utilized until the Gamma4 became available in September 2022. Patients were grouped based on the implant utilized for fixation: Gamma3 (G3) or Gamma4 (G4) and sub-grouped based on the centrum-collum-diaphyseal (CCD) angle of the implant (125° versus 130°).

Outcome measures and comparisons: The main outcome was sliding of the lag screw. Slide distance was calculated from the difference between the screw position immediately post-operatively and at 6 and 12 weeks post-operatively. The secondary outcome variables were revision surgery for any reason, tip-apex distance (TAD), and reduction quality.

Results: Fifty-one patients (40 female) with a mean age of 83 years (range 65-99) were in the G3 group compared to 46 patients (31 female) with a mean age of 79 years (range 65-96) in the G4 group. The average BMI of the G3 group was 24 kg/m2 (15-35 kg/m2) compared to 27 kg/m2 in the G4 group (17-41 kg/m2) (p = 0.004). There were no significant differences when comparing diabetes, smoking status, or mechanism of injury between groups (p>0.05). There was no significant difference when comparing the average TAD between the G3 (10 mm) and G4 (9.5 mm) (p = 0.39). There was no significant difference in reduction quality between the G3 (46 good reductions) and the G4 (42 good reductions) groups (p = 0,85).At 6 weeks, the G4 (5 mm) had significantly greater lag screw slide compared to the G3 (3 mm) (p = 0.016). At 12 weeks, the G4 (7 mm) also had significantly greater lag screw slide when compared to the G3 (4 mm) (p = 0.004). There was no significant difference in lag screw slide for the 125° implant between the G3 and G4 groups at 6-weeks (3 mm versus 5 mm, p = 0.44) or 12 weeks (4mm versus 6 mm, p = 0.14). Regarding the 130° implant, the G4 had significantly greater slide compared to the G3 at both at 6-weeks (5 mm versus 3mm, p =0.03; 95% CI -6.07 to -0.41) and 12-weeks (8 mm versus 4 mm, p = 0.03; 95% CI -5.65 to -0.26). The G4 group had 7 revision procedures performed (3 lag screw exchanges for iliotibial band irritation and 4 revision arthroplasties for lag screw slide, fracture shortening, iliotibial band irritation, abductor malfunction, and leg length discrepancy) compared to 1 revision procedure (lag screw exchange for iliotibial band irritation) in the G3 group (p = 0.04).

Conclusions: The 130° Gamma4 demonstrated increased lag screw slide and all-cause revision surgery when compared to the 130° Gamma3 when utilized in the treatment of geriatric IT femoral fractures. Given the high incidence of increased slide and the significantly higher revision surgery rate, this implant should undergo further investigation.