Wing-augmentation reduces femoral head cutting out of dynamic hip screw.
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 (12mm axial displacement) or up to 20,000 cycles of 1.45kN 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.
Department of Biomedical Engineering, National Yang-Ming University, Linong St, Beitou District, Taipei City, Taiwan; Department of Orthopedics, Shuang Ho Hospital, Taipei Medical University, Wuxing St, Xinyi District, Taipei City, Taiwan. Electronic address: aleckc2424@gmail.com.
Chih-Yu
CY
Chen
Institute of Biomedical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd, Da'an District, Taipei City, Taiwan. Electronic address: judyya1022@gmail.com.
Shu-Wei
SW
Huang
Department of Orthopedic Surgery, National Taiwan University & Hospital, No. 7, Zhongshan S Rd, Zhongzheng District, Taipei City, Taiwan; Biomimetic Systems Research Center, National Chiao Tung University, No. 1001, Daxue Rd, East District, Hsinchu City, Taiwan . Electronic address: drjssun@ntu.edu.tw.
Jui-Sheng
JS
Sun
Department of Orthopedic Surgery, National Taiwan University & Hospital, No. 7, Zhongshan S Rd, Zhongzheng District, Taipei City, Taiwan. Electronic address: linshinyiing@gmail.com.
Shin-Yiing
SY
Lin
Instrument Technology Research Center, National Applied Research Laboratories 20, R&D Rd. VI, Hsinchu Science Park, Hsinchu 300, Taiwan. Electronic address: ycs@itrc.narl.org.tw.
Chih-Sheng
CS
Yu
Instrument Technology Research Center, National Applied Research Laboratories 20, R&D Rd. VI, Hsinchu Science Park, Hsinchu 300, Taiwan. Electronic address: panhp@itrc.narl.org.tw.
Hsu-Pin
HP
Pan
Instrument Technology Research Center, National Applied Research Laboratories 20, R&D Rd. VI, Hsinchu Science Park, Hsinchu 300, Taiwan. Electronic address: lbh@itrc.narl.org.tw.
Ping-Hung
PH
Lin
Instrument Technology Research Center, National Applied Research Laboratories 20, R&D Rd. VI, Hsinchu Science Park, Hsinchu 300, Taiwan. Electronic address: fchsieh@itrc.narl.org.tw.
Fan-Chun
FC
Hsieh
Department of Orthopedics, Shuang Ho Hospital, Taipei Medical University, Wuxing St, Xinyi District, Taipei City, Taiwan. Electronic address: tsuangyh@gmail.com.
Yang-Hwei
YH
Tsuang
Institute of Biomedical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd, Da'an District, Taipei City, Taiwan. Electronic address: double@ntu.edu.tw.
Feng-Huei
FH
Lin
Department of Orthopedic Surgery, National Taiwan University & Hospital, No. 7, Zhongshan S Rd, Zhongzheng District, Taipei City, Taiwan. Electronic address: rsyang@ntuh.gov.tw.
Rong-Sen
RS
Yang
Department of Biomedical Engineering, National Yang-Ming University, Linong St, Beitou District, Taipei City, Taiwan. Electronic address: ckcheng@ortho.ym.edu.tw.
Cheng-Kung
CK
Cheng
D001863:Bone Screws; D005270:Femur Head / Q000601:surgery; D006620:Hip Fractures; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D016474:Weight-Bearing
Cut-out; Dynamic hip screw; Femoral intertrochanteric fracture; Lag screw