Wing-augmentation reduces femoral head cutting out of dynamic hip screw

Chih Yu Chen, Shu Wei Huang, Jui Sheng Sun, Shin Yiing Lin, Chih Sheng Yu, Hsu Pin Pan, Ping Hung Lin, Fan Chun Hsieh, Yang Hwei Tsuang, Feng Huei Lin, Rong Sen Yang, Cheng Kung Cheng

Research output: Contribution to journalArticle

Abstract

The dynamic hip screw (DHS) is commonly used in the treatment of femoral intertrochanteric fracture with high satisfactory results. However, post-operative failure does occur and result in poor prognosis. The most common failure is femoral head varus collapse, followed by lag screw cut-out through the femoral head. In this study, a novel-designed DHS with two supplemental horizontal blades was used to improve the fixation stability. In this study, nine convention DHS and 9 Orthopaedic Device Research Center (ODRC) DHSs were tested in this study. Each implant was fixed into cellular polyurethane rigid foam as a surrogate of osteoporotic femoral head. Under biaxial rocking motion, all constructs were loaded to failure point (12. mm axial displacement) or up to 20,000 cycles of 1.45. kN peak magnitude were achieved, whichever occurred first. The migration kinematics was continuously monitored and recorded. The final tip-to-apex distance, rotational angle and varus deformation were also recorded. The results showed that the ODRC DHS sustained significantly more loading cycles and exhibited less axial migration in comparison to the conventional DHS. The ODRC DHS showed a significantly smaller bending strain and larger torsional strain compared to the conventional DHS. The changes in tip-to-apex distance (TAD), post-study varus angle, post-study rotational angle of the ODRC DHS were all significantly less than that of the conventional DHS (p < 0.05). We concluded that the ODRC DHS augmented with two horizontal wings would increase the bone-implant interface contact surface, dissipate the load to the screw itself, which improves the migration resistance and increases the anti-rotational implant effect. In conclusion, the proposed ODRC DHS demonstrated significantly better migration resistance and anti-rotational effect in comparison to the conventional DHS construct.

Original languageEnglish
Pages (from-to)73-78
JournalMedical Engineering and Physics
Volume44
DOIs
Publication statusPublished - Jun 2017

Keywords

  • Cut-out
  • Dynamic hip screw
  • Femoral intertrochanteric fracture
  • Lag screw

ASJC Scopus subject areas

  • Biophysics
  • Biomedical Engineering

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  • Cite this

    Chen, C. Y., Huang, S. W., Sun, J. S., Lin, S. Y., Yu, C. S., Pan, H. P., Lin, P. H., Hsieh, F. C., Tsuang, Y. H., Lin, F. H., Yang, R. S., & Cheng, C. K. (2017). Wing-augmentation reduces femoral head cutting out of dynamic hip screw. Medical Engineering and Physics, 44, 73-78. https://doi.org/10.1016/j.medengphy.2017.02.015