Objective To investigate and compare the difference between two implants of reconstructing anterior cruciate l igament (ACL) for the early heal ing of implants tunnel interface in terms of biological mechanism. Methods Fiftyfive adult New Zealand rabbits weighing 2.0-2.8 kg were selected. Patellar l igament with tibia-bone block was obtained fromthe left knee joint serving as donor site, right knee joint served as the recipient site of autograft for ACL reconstruction. Thebone block end of implant was bone-bone interface heal ing model, while the l igament end was tendon-bone interface heal ing model. The general condition of rabbits was observed after operation, the gross observation and histology observation were conducted at 2, 4 and 8 weeks after operation (n=5), and biomechanics examination was conducted at 4 and 8 weeks after operation (n=20). Results Rabbits behaved normally after operation. The gross observation indicated that ACL had complete continuity and moderate tension during experiment. Histology observation: most part of bone-bone interface was connected by fibrous tissue, while the tendon-bone interface was mainly filled by granulation tissue 2 weeks after operation; most part of bone-bone interface was bone union, and there were osteogenesis reaction and large quantity of fibroblasts in the tendonbone interface 4 weeks after operation; complete bone union was evident in bone-bone interface, and the appearance of Sharpey fibers and the formation of indirect insertion occured in part of tendon-bone interface 8 weeks after operation. Biomechanics observation: the pull-out rate for tendon-bone interface and bone-bone interface 4 weeks after operation was 85% and 15%, respectively; while it was 95% and 5% 8 weeks after operation, respectively; indicating there was a significant difference between two groups (P lt; 0.001). Conclusion In the early stage after ACL reconstruction, bone-bone interface is better than tendonbone interface in terms of intensity and speed of heal ing.
ObjectiveTo investigate the short-term effectiveness of ISOBAR TTL semi-rigid dynamic stabilization system (ISOBAR TTL system) in treatment of lumbar degenerative disease. MethodsBetween June 2007 and May 2011, 38 cases of lumbar degenerative disease were treated, including 24 males and 14 females with an average age of 51.2 years (range, 21-67 years). The disease duration was 8 months to 10 years (mean, 4.7 years). In 38 cases, there were 4 cases of grade I spondylolisthesis, 11 cases of lumbar instability and lumbar disc protrusion, 21 cases of lumbar spinal stenosis and lumbar disc protrusion, and 2 cases of postoperative recurrence of lumbar disc protrusion. There were 22 cases of adjacent segment disc degeneration. All cases underwent posterior decompression and implantation of ISOBAR TTL system. The double-segment-fixed patients underwent interbody fusion. Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) scores for low back pain were used to evaluate clinical outcomes. The range of motion (ROM) at the semi-rigid dynamic stabilization segment was also measured. ResultsThe other cases achieved healing of incision by first intention, except 1 case of delayed healing. All the patients were followed up 8-53 months (mean, 27.8 months). After operation, ISOBAR TTL system showed reliable fixation, and no loosening, breakage, or kyphosis deformity occurred. No adjacent segment degeneration was observed. The ROM of the fixed segments was 0-1° in 3 cases, 1-2° in 4 cases, 2-3° in 14 cases, 3-4° in 15 cases, and gt; 4° in 2 cases. At last follow-up, the VAS score was 1.93 ± 2.43, and was significantly lower than preoperative score (8.20 ± 1.78) (t=7.761, P=0.000). JOA score was 23.06 ± 7.75, and was significantly higher than preoperative score (4.87 ± 3.44) (t=10.045, P=0.000). According to Stauffer-Coventry evaluation standard, the results were excellent in 32 cases, good in 3 cases, fair in 2 cases, and poor in 1 case, with an excellent and good rate of 92.1%. ConclusionGood short-term effectiveness can be achieved by surgical intervention with ISOBAR TTL system in treatment of lumbar degenerative disease.
Objective To establ ish sophisticated three-dimensional finite element model of the lower cervical spine and reconstruct lower cervical model by different fixation systems after three-column injury, and to research the stress distribution of the internal fixation reconstructed by different techniques. Methods The CT scan deta were obtained from a 27-year-old normal male volunteer. Mimics 10.01, Geomagic Studio10.0, HyperMesh10.0, and Abaqus 6.9.1 softwares were usedto obtain the intact model (C3-7), the model after three-column injury, and the models of reconstructing the lower cervical spine after three-column injury through different fixation systems, namely lateral mass screw fixation (LSF) and transarticular screw fixation (TSF). The skull load of 75 N and torsion preload of 1.0 N•m were simulated on the surface of C3. Under conditions of flexion, extension, lateral bending, and rotation, the Von Mises stress distribution regularity of internal fixation system was evaluated. Results The intact model of C3-7 was successfully establ ished, which consisted of 177 944 elements and 35 668 nodes. The results of the biomechanic study agreed well with the available cadaveric experimental data, suggesting that they were accord with normal human body parameters and could be used in the experimental research. The finite element models of the lower cervical spine reconstruction after three-column injury were establ ished. The stress concentrated on the connection between rod and screw in LSF and on the middle part of screw in TSF. The peak values of Von Mises stress in TSF were higher than those in LSF under all conditions. Conclusion For the reconstruction of lower cervical spine, TSF has higher risk of screw breakage than LSF.