Clinical study on unilateral pedicle screw fixation and interbody fusion for the treatment of lumbar degenerative diseases under Quadrant system / 中国骨伤

<p><b>OBJECTIVE</b>To compare the clinical effects of unilateral pedicle screw fixation (uni-PS) assisted by Quadrant system and bilateral pedicle screw fixation (bi-PS) for the treatment of lumbar degenerative diseases.</p><p><b>METHODS</b>From October 2008 to October 2010,102 patients with lower back pain, unilateral lower limb radiating pain or paraesthesia were treated with pedicle screw fixation and lumbar interbody fusion. There were 67 males and 35 females with an average age of 51.5 years ranging from 34 to 69 years. The patients were randomly divided into two groups (group A and group B) according to the internal fixation type. The patients of group A (n=50) underwent with minimally transforaminal lumbar interbody fusion (TLIF) and unilateral pedicle screw fixation with one single cage placement assisted by Quadrant system;and the patients of group B (n = 52) underwent with posterior lumbar interbody fusion (PLIF) and bilateral pedicle screw fixation with one single cage placement. There were no significant differences between two groups in general information (P > 0.05). VAS score and ODI score system were used to evaluate the preoperative and postoperative pain and function recovery. Operative time, volume of blood loss, fusion rate and complication rate were compared and analyzed by statistical test.</p><p><b>RESULTS</b>All the patients were followed up from 12 to 21 months with an average of 18.2 months. In the group A,operative time and volume of blood loss were (87.6 +/- 25.5) min and (105.7 +/- 27.2) ml, respectively; VAS score of low back pain and leg pain, ODI score decreased respectively from preoperative 7.2 +/- 1.4, 7.9 +/- 1.1, 42.2 +/- 11.8 to 3.2 +/- 0.6, 3.0 +/- 0.7,15.6 +/- 2.3 at one month after operation; the fusion rate was 96.0% (48/50) and the complication rate was 4.00% (2/50). In the group B,operative time and volume of blood loss were (160.3 +/- 20.5) min and (220.6 +/- 25.5) ml, respectively; VAS score of low back pain and leg pain, ODI score decreased respectively from preoperative 7.3 +/- 1.1, 8.1 +/- 0.9, 43.1 +/- 12.0 to 3.3 +/- 0.4, 3.2 +/- 0.3, 14.9 +/- 2.6; the fusion rate was 96.2% (50/52) and the compli- cation rate was 5.77% (3/52). There were no statistically significant differences between the two groups in fusion rate, complication rate, VAS pain and ODI score. Whereas the operative time and blood loss in group A were significantly lower than that of group B.</p><p><b>CONCLUSION</b>Minimally invasive unilateral pedicle screw fixation is a safe and feasible method for the treatment of lumbar degenerative diseases. It is as effective as the bilateral fixation in lumbar spinal fusion. In addition, it has the advantages of short operative time, less volume of blood loss, high fusion rate, etc.</p>

Effects of spondylolysis on mechanical stability of upper lumbar vertebrae / 医用生物力学

Objective To study the stability of upper lumbar vertebra in spondylolysis by measuring the upper vertebra pressure on lumbar spondylolysis models. Method Nine fresh frozen human lumbar spinal specimens were used as experimental models. The pressure on upper vertebral discs of lumbar vertebrae was measured by the material testing machine (MTS 858 Bionix test system)with extension, flexion and axial, bilateral compression being applied on two groups of specimens: 1) intact spine; 2) lumbar spondylolysis. Results Compared with the intact specimens, the pressure of upper lumbar vertebra in spondylolysis was increased by 1.3％，1.5％，1.7％ in axial compression with 600, 800, 1 000 N (the differences were not significant (P＞0.05)), by 20.97％，24.45％，28.79％ in 15°of extension with 300, 500, 700N (the differences were significant (P < 0.01)), by 14.15％，17.86％，24.92％ in 15°of flexion with 300, 500, 700N (the differences were significant (P < 0.01)), by 3.54％，2.12％，1.14％ in 15°of bilateral compression with 300, 500, 700N (the differences were not significant (P＞0.05)). Conclusions Lumbar spondylolysis has a significant mechanical influence on lumbar spine not only at the involved level but also at the upper adjacent level, which can affect the stability of lumbar spine correspondingly.