The Influence of Mallet Mass and Velocity on the Fracture Patterns in Osteotomies

Introduction: Osteotomies are routinely incorporated in rhinoplasty, however, the influence of mass, velocity, kinetic energy (KE), and momentum (p) of the mallet on fracture patterns has not been studied.

Methods: An experimental sledge guillotine setup was designed simulating a mallet strike with adjustable height and mass and 2 mm-thick Sawbone blocks. KE and p were calculated using KE = ½ mass × velocity² and p = mass × velocity formulas. Fracture lengths and angles were measured.

Results: Ten groups with varying mallet masses and drop heights were tested with 10 bones per group. Fracture length positively correlated with KE (R = 0.542, p < 0.001) and p (R = 0.508, p < 0.001). Fracture angle also positively correlated with KE (R = 0.367, p < 0.001) and p (R = 0.329, p < 0.001). In groups with similar KE, osteotomies with higher p (heavier mallet with slower velocity) had greater fracture lengths (29.31 ± 0.68 vs. 27.68 ± 2.12 mm, p = 0.013) but similar fracture angles (p = 0.189). In groups with similar p, osteotomies with higher KE (lighter hammer with faster velocity) had significantly greater fracture lengths (28.28 ± 1.28 vs. 20.45 ± 12.20 mm, p = 0.041) and greater divergent fracture angles (3.13 ± 1.97° vs. 1.40 ± 1.36°, p = 0.031). Regression modeling of the relationship between KE and fracture lengths and angles demonstrated that cubic followed by logarithmic regression models had the best fits.

Conclusion: Osteotomy fracture patterns positively correlated with the mallet's KE more so than its p, suggesting that the mallet's velocity has an increased impact effect than its mass. Clinically, a heavier mallet with a lower velocity will likely generate a smaller fracture length and fracture angle, indicating a more controlled and ideal fracture.

Level of evidence: NA Laryngoscope, 2024.