ObjectiveTo analyze the effectiveness of direct screw repair for lumbar spondylolysis by using intraoperative O-arm based navigation and microendoscopic techniques. MethodsBetween February 2012 and May 2014, 11 consecutive patients with lumbar spondylolysis were treated with Buck's procedure by the aid of intraoperative O-arm based navigation and minimally invasive approach. The debridement and autograft of pars interarticularis defects was performed under microendoscopy. There were 7 males and 4 females, with an average age of 28.4 years (range, 19-47 years) and an average disease duration of 10.5 months (range, 8-23 months); no nerve symptoms or signs of lower limb was observed. The radiological examinations showed single level bilateral lumbar spondylolysis without obvious disc degeneration, lumbar instability, or spondylolisthesis. Isthmic injury located at L4 in 2 cases and at L5 in 9 cases. Of 11 patients, 7 were rated as grade 2 disc degeneration, and 4 as grade 3 disc degeneration according to the modified Pfirrmann classification system. The operation time, intraoperative blood loss, and complications were recorded. The fluoroscopic examinations were performed to assess defect repair and screw position. Visual analogue scale (VAS) score was used to evaluate the improvement of low back pain. ResultsThe average operation time was 147.6 minutes (range, 126-183 minutes). The average blood loss was 54.9 mL (range, 40-85 mL). Primary healing of incision was obtained. There was no complication of nerve root injury, dural tear, or infection. Three patients had pain at donor site postoperatively, and pain disappeared within 3 weeks. The average follow-up duration was 15.7 months (range, 10-23 months). VAS score of low back pain was significantly decreased from preoperative 7.1±2.3 to 1.8±0.4 at last follow-up (t=13.42, P=0.01). Of 22 isthmic bone grafting, bilateral isthmic bony fusion was achieved in 7 patients and unilateral isthmic bony fusion in 3 patients at 6-10 months (mean, 7.9 months). One patient failed bilateral isthmic bony fusion, and had bony resorption. ConclusionDebridement, autograft, and percutaneous intralaminar screw fixation by microendoscopy and O-arm based navigation may provide safe and effective treatment for spondylolysis. Minimally invasive direct repair can obtain satisfactory effectiveness.
ObjectiveTo investigate the effect of cyclic stretch stress on the osteogenic differentiation of human cartilage endplate-derived stem cells (CESCs). MethodsCESCs were isolated from the endplate cartilage tissues by the method of agarose suspension culture system. The endplate cartilage tissue was harvested for immunohistochemical staining. Flexercell-4000TM Tension Plus system was used to apply cyclic stretch on CESCs at a frequency of 1 Hz and at a stretch rate of 10% for 1, 6, 12, or 24 hours (experimental group). No stretch stress was performed on CESCs in the same culture condition (control group). After mechanical loading, the protein expression of bone morphogenetic protein 2 (BMP-2) was measured by Western blot, and gene expressions of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), and SOX9 were detected by real-time fluorescent quantitative PCR. ResultsImmunohistochemical staining showed BMP-2 protein expression in chondrocytes. The continuous cyclic stretch stress of 10% can increase the expression of BMP-2 protein in CESCs. Significant differences were observed in the expressions of BMP-2 protein (P<0.05) between 2 groups at the other time points except at 1 hour (P>0.05), in a time-dependent manner. The real-time fluorescent quantitative PCR indicated that the gene expressions of Runx2 and ALP showed an increasing tendency with time in the experimental group when compared with the control group, but there was down-regulated expression of SOX9. Significant difference was found in mRNA expressions of Runx2 and ALP at 12 and 24 hours and in mRNA expressions of SOX9 at 6, 12, and 24 hours between 2 groups (P<0.05), in a time-dependent manner. ConclusionCyclic stretch stress may induce osteogenic differentiation of CESCs by regulating the expressions of some genes related osteogenesis in CESCs.