Objective To explore the influence of discectomy and artificial disc replacement on the upper lumbar facet joint and to provide the evidence for use of artificial disc replacement. Methods Under the loads of 200-2 000 N axis pressure and 1-10 Nm back-extending/side-bending pressure on the 7 fresh adult corpses, the pressure of L3,4facet joint was measured in the case of L4,5disc integrity, discectomy and artificial disc replacement and the statistical analysis was done.ResultsUnder the same load (axis, back-extending/side bending), there were significant differences (Plt;0.01) in the pressure of upper lumbar facet jointboth between disc integrity and discectomy and between discectomy and artificial disc replacement, and there was no difference(Pgt;0.05) between disc integrity and artificial disc replacement. Conclusion The stress ofupper lumbar facet joint reduced after discectomy, it implies that simply discectomy may change biomechanics of lumbar and lead to secondary lumbar structure degeneration. The stress of upper lumbar facet joint is close to the normal value after artificial disc replancement, it implies that artificial disc replacement may protect lumbar structure. It provides some biomechanics foundation and evidence for artificial disc replacement.
Objective To research the biomechanical effect of different length bone plates on treatment of tibial shaft fracture. Methods Forty-five tibia specimens from fresh adult corpse (20-40 years old) were donated (30-38 cm in length, 34 cm on average) and were divided into 3 groups randomly (n=15). Under the following three conditions, the experiment was made separately. Compression stress-strain indexes of whole tibia were determined under the reverse, three spots curving and compression. The vertical elastic strain was 0-1 000 N, the reverse angle was 0-3º, and three bending stresswas 0-400 N. Then the center-section squint non-damage bone fracture model was made, fracture was fixed by 6, 10, 14stainless steel AO LC-DCP, respectively. The compression stress-strain indexes were determined under reverse angle, three spots curving and compression, statistical analysis was done. Results The vertical direction strain value of 6, 10 and 14 hole steel plate under vertical compressions, was 0.449 ± 0.241, 0.093 ± 0.003, 0.139 ± 0.005, respectively ; showing significant difference between 10 and 14 hole steel plates and 6 steel plate (P lt; 0.01) and no significant difference between 10 and 14 hole steel plate (P gt; 0.05). The lateral strain value of 6, 10 and 14 hole steel plate was 0.120 0 ± 0.000 4, 0.127 5 ± 0.010 0, 0.237 0 ± 0.000 6 respectively, indicating a significant difference between stell plates of 6 and 10 hole and 14 hole steel plate (P lt; 0.01) and no difference between 6 and 10 hole steel plate (P gt; 0.05). The torque of 6, 10 and 14 hole steel plate was (5.066 ± 2.715) × 10-3, (5.671 ± 2.527) × 10-3 and (4.570 ± 2.228) × 10-3 Nm, respectively and three spot curving vertical direction strain value was 0.049 ± 0.009, 0.124 ± 0.017, 0.062 ± 0.009, respectively. There were significant differences between various steel plates (P lt; 0.01). Conclusion For the fixation of tibial obl ique fracture, 14 hole steel plate’s stabil ities of anti-vertical compression, anti-reverse and anti-curving are better than those of 6 hole steel plate under the condition of the same material qual ity, thickness, width and screw quantity used.
Objective To investigate the effectiveness of three-dimensional strapping reduction in treatment of patellar fracture. Methods Between January 2015 and June 2015, thirty-two patients were randomly allocated to three-dimensional strapping reduction group (trial group) and towel clamp reduction group (control group). There was no significant difference in age, gender, damage side, interval from injury to opreration, fracture pattern, and cause of injury (P>0.05). The operation time, fluoroscopy time, fracture healing time, postoperative Hospital for Special Surgery (HSS) scores, and complications were collected and analysed. Results All incisions healed at stage I. All patients of 2 groups were followed up 10-14 months (mean, 12.4 months). The operation time and fluoroscopy time of trial group were both shorter than those of control group (t=6.212, P=0.000; t=6.585, P=0.000). X-ray films showed that the fractures in both groups healed successfully and there was no significant difference in healing time between groups (t=1.973, P=0.058). Bone nonunion, infection, and failure fixation were not found in both groups. HSS scores of trial group (91.6±3.8) was higher than that of control group (86.4±5.5) (t=–3.105, P=0.004). Conclusion Compared with towel clamp reduction, the three-dimensional strapping reduction in treatment of patellar fracture has the advantages of shorter operation time and fluoroscopy time, better knee function after operation, and satisfactory fracture healing.