Introduction: Cementless total hip replacement stems require femoral canal preparation with precision
broaching press fit and long-term bone ingrowth. While existing BFX broaches are effective
for most femurs, they perform poorly on sclerotic femoral bone. This study aimed to
(1) develop a drop-test system to more closely simulate clinical broach impaction,
and (2) evaluate three broach tooth designs in simulated healthy or sclerotic bone.
Materials and Methods: A drop-tower apparatus was fabricated to impact broaches into polyurethane blocks
of densities simulating healthy (15 pcf) and sclerotic (25 pcf) bone. A 6.2 lb weight
was dropped from 5 in, generating 3.5 Joules per strike. Impact force was established
within clinical ranges using cadaveric data from a related study. Three broach designs
(Control, TG1 with V-grooves, and TG2 with diamond teeth) were tested for total impacts
and cumulative energy for full insertion. Data were analysed with one-way ANOVA and
Tukey HSD post hoc testing (ɑ = 0.05).
Results: The apparatus effectively simulated clinical impaction, delivering 3.4 kN (±0.46)
for Control broaches. TG2 required significantly more hits (11.6 ± 1.4 in 15 pcf,
44.0 ± 12.15 for 25 pcf) and energy (40.7 J ± 4.9 for 15 pcf, 154.0 J ± 33.13 for
25 pcf) than Control (4.1 ± 0.35 hits, 14.4 J ± 1.23 for 15 pcf; 23.5 ± 2.66 hits,
82.3 J ± 9.33 for 25 pcf) and TG1 (4.1 ± 0.35 hits, 14.4 J ± 1.23 for 15 pcf; 26.2 ± 4.67
hits, 91.6 J ± 16.3 for 25 pcf).
Discussion/Conclusion: The study validates an improved broach testing system and highlights the reduced
cutting efficiency of test broaches.
Acknowledgment
Funded by the Ginn Fund, Texas A&M University.
