A comparison between a hinged plate and screw system and a conventional tension-band plate and screw system used for correction of an angular deformity of the lower limb: an animal study.
BACKGROUND
The purpose of the animal study is to introduce a newly designed hinged plate and screw system for correction of angular deformities of the lower limbs. The technique was compared with the use of a conventional tension-band plate and screw system.


METHODS
This is a randomized controlled animal trial. Eight 3-month-old Bama miniature pigs were used to establish animal models. In each animal, one leg was randomly allocated into study group and another leg into control group. Legs of the study group were corrected with a hinged plate and screw system, and legs of the control group were corrected with a conventional tension-band plate and screw system. The corrective rates of medial slope angle, medial proximal tibial angle, and angle of the two arms of the hinged plate were measured. Residual stress on the implants was also evaluated. A P < 0.05 was statistical significant.


RESULTS
At the final measurements of 18 weeks, the mean corrective rates of medial slope angle, medial proximal tibial angle, and angle of the two arms of the study group were 0.71°/week, 0.85°/week, and 2.18°/week, respectively; the data in the control group were 0.84°/week, 0.89°/week, and 2.13°/week, respectively. No significant difference was found between the groups regarding the mean corrective rates of the angles (P < 0.05). The mean residual stress in the study group was 643.35 MPa, and measurement in the control group was 1,273.63 MPa, with a significant difference (P < 0.05).


CONCLUSIONS
Compared to the conventional tension-band plate and screw system, the hinged plate and screw system may be more reliable for correction of angular deformities of the lower limb.
Department of Pediatric Orthopaedics, Xin-Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, No. 1665, Kongjiang Road, Shanghai, 200092, China. w993167wmg@163.com.
Zhenkai
Z
Wu
Department of Pediatric Orthopaedics, Xin-Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, No. 1665, Kongjiang Road, Shanghai, 200092, China. zdhyjj2001@126.com.
Dahang
D
Zhao
Department of Pediatric Orthopaedics, Xin-Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, No. 1665, Kongjiang Road, Shanghai, 200092, China. orthzl@126.com.
Li
L
Zhao
Department of Pediatric Orthopaedics, Xin-Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, No. 1665, Kongjiang Road, Shanghai, 200092, China. 13120731680@163.com.
Jianlin
J
Liu
Department of Pediatric Orthopaedics, Xin-Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, No. 1665, Kongjiang Road, Shanghai, 200092, China. osteolihai@gmail.com.
Hai
H
Li
Department of Pediatric Orthopaedics, Xin-Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, No. 1665, Kongjiang Road, Shanghai, 200092, China. Zhu_jie@outlook.com.
Jie
J
Zhu
School of Materials Science & Engineering, University of Shanghai for Science and Technology, No. 516, Jungong Road, Shanghai, Shanghai, 200093, China. mafengcang@163.com.
Fengcang
F
Ma
Department of Orthopaedic Surgery, Edinburgh Orthopaedic Trauma Unit Royal Infirmary of Edinburgh, Edinburgh, EH16 4SU, UK. daniel.porter@ed.ac.uk.
Daniel Edward
DE
Porter
D000818:Animals; D001860:Bone Plates; D001863:Bone Screws; D004195:Disease Models, Animal; D017880:Limb Deformities, Congenital / Q000601:surgery*; D035002:Lower Extremity / Q000601:surgery*; D008297:Male; D011897:Random Allocation; D013552:Swine