2023, Vol. 27 ›› Issue (9): 1330-1334

Biomechanical characteristics of a new multi-dimensional cross locking plate in the treatment of subtrochanteric nonunion

Wu Taoguang1, 2, Nie Shaobo2, Chen Hua2, Zhu Zhengguo1, Qi Lin1, Tang Peifu2   

Abstract: BACKGROUND: New multi-dimensional cross locking plate (MDC-LP-II), as an additional plate with retaining intramedullary nail, can achieve more fixations of locking screws and the number of cortical layers in a limited space, but its mechanical stability in models of nonunions after intramedullary nailing of subtrochanteric fractures is uncertain.  
OBJECTIVE: To compare biomechanical differences between MDC-LP-II and conventional locking compression plate as an additional plate in the treatment of postoperative nonunion after intramedullary nailing of subtrochanteric fractures.
METHODS:   Ten artificial femoral models were used to establish the nonunion structure after intramedullary nailing of the subtrochanteric fracture, which were randomly divided into two groups (n=5 per group). After fixation of the nonunion ends with MDC-LP-II and locking compression plate, static torsional failure tests were performed, starting at 0 N·m and loading at 6(°)/min, with continuous recording of the torsional angle-torque curve until the complete destruction of the specimen structure. The torsional rigidity, ultimate torque at yield, and angle at failure of both were recorded and calculated.  
RESULTS AND CONCLUSION: The torsional rigidity was (3.56±0.19) N·m/(°) for MDC-LP-II and (1.69±0.41) N·m/(°) for locking compression plate. The torsional rigidity was elevated by 1.87 N·m/(°) for MDC-LP-II compared with locking compression plate, which was 2.11 times (P < 0.001). When yielding occurred for MDC-LP-II and locking compression plate, the ultimate torque was (73.58±3.28) N·m and (59.88±6.74) N·m respectively, with MDC-LP-II increasing 13.7 N·m more than locking compression plate, which was 1.23 times that of the locking compression plate (P < 0.05). When the specimens were thoroughly destroyed, the destruction angle was (22.50±1.58)° for MDC-LP-II and (31.00±2.85)° for locking compression plate, and was significantly smaller for MDC-LP-II than for locking compression plate (P < 0.001). Due to the stronger torsional rigidity of MDC-LP-II, which is less prone to deformation, and the better biomechanical stability as an additional plate than locking compression plate, MDC-LP-II is the reliable option for the clinical treatment of nonunions after intramedullary nailing of subtrochanteric fractures.
Key words: multi-dimensional cross locking plate, additional plating, femur, subtrochanteric fracture, nonunion, biomechanics