Biomechanical Properties of Porous Titanium Cages for Different Lumbar Interbody Fusion Surgeries / 医用生物力学

Objective To study the biomechanical properties of porous titanium cages used for different lumbar interbody fusion surgeries. Methods The three-dimensional (3D) finite element model of the lumbar spine was constructed, and mechanical parameters of porous materials were obtained by mechanical test. The biomechanical properties of porous titanium cages in anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), direct lateral interbody fusion (DLIF) were compared. Results After lumbar interbody surgery, the predicted range of motion (ROM) and the maximum stress in cage of DLIF model and ALIF model were substantially lower than those of PLIF model and TLIF model. The maximum stress in endplate of DLIF model, ALIF model and TLIF model were obviously lower than that of PLIF model. Conclusions DLIF with the porous cage showed advantages in biomechanical properties, which was simple to operate and suitable for minimally invasive surgery in clinical practice. DLIF performed the superior comprehensive properties.

The Result of Minimal Invasive Anterior Lumbar Interbody Fusion with Posterior Lumbar Interbody Fusion on Degenerative Lumbar Flat Back Disease

STUDY DESIGN: Restrospective study. OBJECTIVES: We tried to find out the effects of minimal invasive anterior lumbar interbody fusion (ALIF) combined with posterior lumbar interbody fusion for degenerative lumbar flat back disease. SUMMARY OF LITERATURE REVIEW: ALIF combined with PLIF is effective in correcting lumbar lordosis. However, the complication rate with conventional ALIF is higher on the lower level. MATERIALS AND METHODS: 21 cases (9 men and 12 women, 46-83 years of age) of having undergone minimal invasive ALIF and PLIF due to degenerative flat back disease were reviewed. The follow-up period was an average of 23 months. We compared the pre-postoperative pain, the functional outcome, the correction of sagittal imbalance and lordotic angle. RESULTS: At final follow-up, 21 cases with the solid fusion experienced a great improvement in their lower back pain(VAS: 7.3 --> 2.6) and leg pain (VAS: 7.0 --> 2.7) and ODI(38.5 --> 18.1). And we experienced correction in sagital imbalance. On levels with anterior fusion, lordotic angle is corrected 6.3 degrees while on levels with posterior fusion, lordotic angle is corrected 9.7 degrees. Plumb line is corrected by 5.2cm, and no complication was found in the follow-up period. CONCLUSIONS: Combined surgery with minimal invasive anterior lumbar interbody fusion and posterior fusion is an effective procedure on patients who need long level surgery for correction of lumbar deformity and decompression.

A Morphometric Analysis of Neuroforamen in Grade I Isthmic Spondylolisthesis by Anterior Lumbar Interbody Fusion with Pedicle Screw Fixation

OBJECTIVES: The aim of this study was to evaluate the morphometric changes in neuroforamen in grade I isthmic spondylolisthesis by anterior lumbar interbody fusion (ALIF). METHODS: Fourteen patients with grade I isthmic spondylolisthesis who underwent single level ALIF with percutaneous pedicle screw fixation were enrolled. All patients underwent standing lateral radiography and magnetic resonance imaging (MRI) before surgery and at 1 week after surgery. For quantitative analysis, the foraminal height, foraminal width, epidural foraminal height, epidural foraminal width, and epidural foraminal area were evaluated at the mid-portion of 28 foramens using T2-weighted sagittal MRI. For qualitative analysis, degree of neural compression in mid-portion of 28 foramens was classified into 4 grades using T2-weighted sagittal MRI. Clinical outcomes were assessed using Visual Analogue Sale (VAS) scores for leg pain and Oswestry disability index before surgery and at 1 year after surgery. RESULTS: The affected levels were L4-5 in 10 cases and L5-S1 in 4. The mean foraminal height was increased (p<0.001), and the mean foraminal width was decreased (p=0.014) significantly after surgery. The mean epidural foraminal height (p<0.001), epidural foraminal width (p<0.001), and epidural foraminal area (p<0.001) showed a significant increase after surgery. The mean grade for neural compression was decreased significantly after surgery (p<0.001). VAS scores for leg pain (p=0.001) and Oswestry disability index (p=0.001) was decreased significantly at one year after surgery. CONCLUSION: Foraminal stenosis in grade I isthmic spondylolisthesis may effectively decompressed by ALIF with percutaneous pedicle screw fixation.

Anterior Lumbar Interbody Fusion with Pedicle Screw Fixation for Elderly Isthmic Spondylolisthesis

OBJECTIVE: The surgical outcome of anterior lumbar interbody fusion(ALIF) with pedicle screw fixation for elderly isthmic spondylolisthesis was analyzed. METHODS: Consecutive nineteen elderly patients (aged 65 years or more) with isthmic spondylolisthesis (Grade I or II) who underwent single level ALIF with pedicle screw fixation in 2002 were analyzed. Using clinical chart and mailed questionnaires, preoperative and postoperative Visual Analogue Scale(VAS) of back and leg pain and postoperative Macnab criteria were evaluated. RESULTS: The mean age at the time of operation was 68.4 years (range 65 to 78 years). Twelve patients underwent ALIF with percutaneous pedicle screw fixation. Seven patients underwent ALIF followed by posterior decompression and pedicle screw fixation. The postoperative complication rate was 10.5% (wound dehiscence in 1 patient and incisional hernia in 1 patient). There was no postoperative major morbidity or mortality. At a mean follow-up duration of 30.7 months (range 25 to 35 months), 93.3% (14/15) of the patients showed excellent or good outcomes in terms of Macnab criteria. The mean VAS scores of back pain and leg pain significantly decreased after surgery. CONCLUSION: ALIF with pedicle screw fixation yielded favorable results for elderly isthmic spondylolisthesis in selected cases.

Isthmic Spondylolisthesis Associated with Foraminal Disc Herniation Treated by Anterior Lumbar Interbody Fusion

A 45-year-old man presented with lower back pain and pain in the right leg of 3years duration. A plain radiographic examination revealed grade I isthmic spondylolisthesis, with instability at L4-5. Computed tomography and magnetic resonance imaging demonstrated bilateral foraminal stenosis, with soft foraminal disc herniation on the right side at the L4-5 level. He underwent anterior lumbar interbody fusion(ALIF) with percutaneous posterior fixation(PF) at the L4-5 level. Without removing the posterior bony structures, removal of foraminal disc herniation and reduction of spondylolisthesis were successfully performed using ALIF with percutaneous PF. When there is no hard disc herniation or lateral recess stenosis, ALIF with percutaneous PF can be one of the treatment options for isthmic spondylolisthesis, even in the presence of foraminal disc herniation, as in our case.