ABSTRACT
BACKGROUND:Effects of pedicle screw placement on fracture reduction or stability of mechanics are influenced by various factors. Pedicle screw fixation failure is mainly due to fracture, loosening and fatigue. The main influential factors for biomechanical stability of pedicle screw are length and diameter. The research on the depth is less. OBJECTIVE:To analyze the relationship between pedicle screw placement depth of vertebral body and the fixed stability based on the biomechanics. METHODS: A model of single vertebral compression fractures was made in 15 pigs aged 5 months on L2 vertebral specimen. According to the length of anteroposterior diameter, vertebral pedicle screws were inserted in different depths (80%, 90% and 100% of anteroposterior diameter). After fixation, specimens were loaded 10 000 times at the frequency of 0.5 Hz (340±125) N on a WDT-10KN type universal material testing machine. Ranges of motion at anteflexion, backward extension, left bending and right bending and the maximum axial pulout force were measured in each group, and the difference of intergroup data was compared. RESULTS AND CONCLUSION:(1) Ranges of motion at anteflexion, backward extension, left bending and right bending in each group were significantly smaler in the 100% and 90% groups than in the 80% group (P 90% group > 80% group.
ABSTRACT
BACKGROUND:The distal tibia shaft fracture is prone to be comminuted after trauma due to the absence of muscle covering and the thin soft tissue, and intraoperative reduction and fixation are difficult. Clinical efficacy is closely related to the type of fracture, degree of soft tissue injury, choice of therapy and internal fixation. Internal fixation is the main treatment for the distal tibia shaft fracture, and a microinvasive, strong fixation is the focus of tibial fracture treatment although many methods for internal fixation are present. ＜br> OBJECTIVE:To explore clinical efficacy of the treatment of distal tibia shaft fracture using percutaneous locking compression plate, interlocking intramedul ary nail and open reduction with internal fixation. ＜br> METHODS:A total of 180 patients with distal tibia shaft fracture were randomized into three groups, receiving internal fixation treatment using percutaneous locking compression plate, interlocking intramedul ary nail or open reduction. Al patients were fol owed up for 12-24 months. The clinical outcomes of the treated patients in three ＜br> groups were compared through the observations of incision length, operation time, intraoperative fluoroscopy time, intraoperative blood loss, complications after fixation. ＜br> RESULTS AND CONCLUSION:After excluding the loss of fol ow-up, 56 cases receiving percutaneous locking compression plate, 52 cases receiving interlocking intramedul ary nail and 48 cases receiving open reduction were involved in the final analysis. The incision length and intraoperative blood loss in the groups of percutaneous locking compression plate and interlocking intramedul ary nail were significantly better than that of open reduction (P＜0.05). Intraoperative fluoroscopy time in the group of percutaneous locking compression plate was significantly longer than that in other two groups (P＜0.05). The operation time showed no significant differences among three groups. The rate of complications was 11%in the group of percutaneous locking compression plate, and 27%in the groups of interlocking intramedul ary nail and open reduction with internal fixation. Percutaneous locking compression plate is a good choice for the distal tibia shaft fracture due to smal injury, good biomechanical stability, and no influence on blood supply at fracture end;interlocking intramedul ary nail is also a useful technique due to simple operations. Open reduction with internal fixation should be chosen careful y due to great dissection, great influence on blood supply and high complication rate.
