Yong Hai

Biomechanical effect of interspinous dynamic stabilization adjacent to single-level fusion on range of motion of the transition segment and the adjacent segment

BACKGROUND Despite numerous biomechanical studies have been carried out on dynamic stabilizers, there is very little information on their hybrid application, especially when combined interspinous dynamic stabilization with single-level fusion. The aim of this study is to assess the biomechanical effect of interspinous dynamic stabilization adjacent to single-level fusion on range of motion of the transition segment and the adjacent segment. METHODS Six fresh lumbosacral spines (L2-S1) were tested in the following sequence: 1) intact (Construct A); 2) fusion in L5/S1 and intact in L4/5 (Construct B); 3) fusion in L5/S1 and unstable state in L4/5 (Construct C); 4) fusion in L5/S1 and Coflex in L4/5 (Construct D). Range of motion (at L3/4 and L4/5) was recorded and calculated. FINDINGS Range of motion in L3/4 in the four constructs showed no difference under all motion states. Under flexion/extension, the range of motion of L4/5 in Construct B and Construct C increased, while the range of motion of L4/5 in Construct D decreased compared with Construct A. Compared with Construct D, the range of motion of L4/5 in Constructs B and C showed a significant increase. Under lateral bending and axial rotation, Construct A showed similar range of motion of L3/4 compared with other constructs. INTERPRETATION Fusion combined with Coflex is able to stabilize the transition segment and restrict flexion and extension in that segment, while having no significant effect on the range of motion of the adjacent segment or the range of motion of the transition segment under lateral bending and axial rotation.

Optimum pelvic incidence minus lumbar lordosis value after operation for patients with adult degenerative scoliosis

BACKGROUND CONTEXT Schwab classification for adult degenerative scoliosis (ADS) concluded that health-related quality of life was closely related to curve type and three sagittal modifiers. It was suggested that pelvic incidence minus lumbar lordosis value (PI-LL) should be corrected within -10°~+10°. However, recent studies also indicated that ideal clinical outcomes could also be achieved in patients without the ideal PI-LL mentioned above. PURPOSE This study evaluated the relation between the clinical outcomes and the PI-LL of Chinese patients with ADS who received long posterior internal fixation and fusion. STUDY DESIGN This was a single-center retrospective comparative study of patients treated by long posterior internal fixation and fusion in our hospital between 2010 and 2014. PATIENT SAMPLE Inclusion criteria were age >45 years at the time of surgery, Cobb angle of lumbar curves ≥10°, long posterior internal fixation and fusion ≥least 3 motion segments, follow-up ≥2 years, complete preoperative and postoperative radiographic data, and functional evaluation results. Exclusion criteria were history of previous lumbar spine surgery, other kinds of scoliosis, history of severe spinal trauma, spinal tumor, ankylosing spondylitis, and spinal tuberculosis. Seventy-four patients were enrolled in this study. OUTCOME MEASURES Operative parameters included intraoperative blood loss, duration of surgery, length of hospital stay, number of fusion levels, and decompression. The radiological measurements included Cobb angle of the curves and PI-LL. Clinical outcomes were evaluated by the Japanese Orthopaedic Association score, Oswestry Disability Index (ODI), visual analog scale, and Lumbar Stiffness Disability Index (LSDI). In addition, the complications of surgery were also collected. One-way analysis of variance, Student t test, Kruskal-Wallis test, Pearson chi-square test, and curve estimation were calculated for variables. METHODS All the patients were divided into Group 1 (long instrumentation and fusion to L5) and Group 2 (long instrumentation and fusion to S1). Operative parameters, radiological measurements, clinical outcomes, and complications of surgery were compared between two groups to confirm whether distal fusion level could influence therapeutic effect. Then patients were divided into PI-LL<10° (Group A), 10°≤PI-LL≤20° (Group B), PI-LL>20° (Group C). Operative parameters, radiological measurements, clinical outcomes, and complications of surgery were compared between each of the two groups. Curve estimation was performed to evaluate the relationship between postoperative PI-LL and clinical outcomes. RESULTS No difference was found between Group 1 and Group 2 in all postoperative parameters (p>.05). There were significant differences in final ODI (p<.001) and final LSDI (p<.001) among Group A, Group B, and Group C. Cubic curve model fitted the relationship between PI-LL and final ODI better than other models (R2=0.379, p<.001). Cubic curve model fitted the relationship between PI-LL and final LSDI better than other models (R2=0.691, p<.001). There was a significant difference in proximal junctional kyphosis (PJK) among groups (p=.038). No significant difference was found in other parameters. CONCLUSIONS Optimal PI-LL value may be achieved between 10° and 20° in Chinese patients with ADS after long posterior instrumentation and fusion surgery with excellent clinical outcomes and a lower PJK occurrence.

Distal Adding-on and Risk Factors in Severe and Rigid Scoliosis.

Study Design. A retrospective study. Objective. The aim of this study was to identify associated risk factors of distal adding-on in severe and rigid scoliosis. Summary of Background Data. Previous work has evaluated the challenges in the treatment of patients with severe and rigid scoliosis and the risks of complications. Furthermore, although several studies have investigated postoperative distal adding-on and attendant risk factors in Lenke type 1A scoliosis, very few have focused on distal adding-on in severe and rigid scoliosis. Methods. In this study, 48 consecutive patients with severe and rigid scoliosis underwent posterior spinal fusion surgery. The parameters of preoperative, immediately postoperative, and minimum 2-year follow-up radiographs were evaluated. The patients were classified as positive or negative for distal adding-on at follow-up, and risk factors were comparatively analyzed in the two groups. Results. The average Cobb angle and flexibility of the main thoracic curve (MTC) were 107.4° ± 15.9° and 16.4% ± 10.2%, respectively, before surgery. Distal adding-on was observed in 12 patients (25.0%) at follow-up. Univariate analysis identified several factors significantly associated with distal adding-on. Furthermore, significant independent risk factors identified by stepwise logistic regression analysis included the correction rate of the MTC immediately after surgery (odds ratio: 1.107, 95% confidence interval: 1.024–1.197, P = 0.011) and the difference between the lower instrumented vertebra (LIV) and last touching vertebra (LTV) levels (odds ratio: 0.121, 95% confidence interval: 0.028–0.518, P = 0.004). Conclusion. In severe and rigid scoliosis, a high correction rate of the MTC immediately after surgery and the LIV level above the LTV were significantly associated with distal adding-on. Level of Evidence: 3

Evaluation of Hyperbaric Oxygen Treatment in Acute Traumatic Spinal Cord Injury in Rats Using Diffusion Tensor Imaging

This study aimed to evaluate the therapeutic effect of hyperbaric oxygen (HBO) on acute spinal cord injury (SCI) by measuring the in vivo diffusion tensor imaging (DTI) parameters apparent diffusion coefficient (ADC) and fractional anisotropy (FA) and observing diffusion tensor tractography (DTT) of fiber bundle morphology. The rats were randomly divided into sham-operated (SH), SCI, and SCI and hyperbaric oxygen treatment (SCI + HBO) groups (n = 6 in each group). The Basso-Bettie-Bresnahan (BBB) score was used to evaluate motor function recovery, and DTI was performed on days 3, 7, 14, and 21 after surgery. BBB scores and FA values decreased significantly after SCI, while the two values significantly improved in the SCI + HBO group compared with the SCI group on days 7, 14, and 21. ADC increased significantly on days 14 and 21 postoperatively in the SCI group compared with the SH group but did not significantly differ between the SCI and SCI + HBO groups at any time point. BBB scores had the same variation trend with ADC values and FA values in all three groups. In the SH group, DTT showed a well-organized spinal cord, but the spinal cord showed interruptions at sites of injury after SCI. In conclusion, HBO promotes the recovery of neuronal function after SCI. Parameters of DTI, especially FA, can quantitatively evaluate the efficacy of HBO treatment in SCI, while DTT enables the visualization of the fiber tracking of spinal cord tracts.

Long-term clinical results following Charite III lumbar total disc replacement

BACKGROUND CONTEXT Lumbar total disc replacement (TDR) operation represents an alternative to lumbar fusion for the treatment of symptomatic lumbar intervertebral disc degeneration and has gained increasing attention in recent years. PURPOSE This study aimed to assess clinical outcomes in a cohort of patients with TDR and the long-term survival rate of the prostheses. STUDY DESIGN This is a retrospective, single-center clinical study. PATIENT SAMPLE The sample comprised 30 patients, giving a total of 35 prostheses after an average follow-up (FU) of 15.2 years following TDR, which was performed for the treatment of lumbar degenerative disc disease. OUTCOME MEASURES Clinical evaluation included visual analog scale (VAS) and the Oswestry Disability Index (ODI). Radiological parameters of intervertebral disc height (IDH), range of motion (ROM), lumbar lordosis, lumbar scoliosis, and prosthesis position were evaluated in surgical and adjacent levels. Complications and re-operation rates were also assessed. METHODS Clinical evaluation and radiological parameters were evaluated preoperatively and at final FU. All data were collected by members of our department, including research assistants and nurses who were not involved in the decision making of this study. RESULTS Thirty of the 35 patients participated in the final FU. The cumulative survival rate of the prosthesis at a mean FU of 15.4 years was 100%. The clinical success rate was 93.3%. The VAS and ODI scores at final FU were significantly lower than preoperatively (p<.001). The average ROM of the operated and superior adjacent segment decreased significantly at the final FU, whereas the inferior adjacent segment was not affected. The IDH of all surgical and adjacent levels were well maintained at the final FU. Ten patients had a lumbar scoliosis >3° and the mean angle was 8.5°, of which 7 had left convex curvature. Three prostheses were offset more than 5 mm from the midline on the coronal plane. Four prostheses showed subsidence. Twenty-six operative segments and five adjacent segments showed heterotopic ossification. Two patients of the total 35-patient cohort underwent a secondary operation. CONCLUSIONS Satisfactory clinical results and good prosthesis survival can be achieved in the long term. Lumbar TDR surgeries also have the potential to reduce the incidence of adjacent segment disease.

Prospective Clinical and Radiographic Results of Activ L Total Disk Replacement at 1- to 3-Year Follow-up.

Study Design: A prospective clinical study. Objective: To assess the clinical and radiographic results of activ L total disk replacement (TDR) on degenerative disk diseases. Summary of Background Data: There are few reports on Activ L TDR, and this is the first in China. Materials and Methods: From March 2009 to March 2012, 32 patients with degenerative disk disease underwent either monosegmental or bisegmental lumbar TDR, which was documented in a prospective observational mode. Clinical success was defined as disability [Oswestry Disability Index (ODI)] improvement of at least 15 points versus baseline, no device failure, no major complications, no neurological deterioration. Additional clinical parameters as Visual Analogue Scale and Oswestry Disability Index (ODI) were evaluated preoperatively and postoperatively (1, 2, and 3 y). Radiographic parameters as range of motion (ROM) and intervertebral disk height (IDH) of the index and adjacent segments were also carried out. Prosthesis subsidence and heterotopic ossification were observed during the follow-up period. Work status was tracked for all patients. Results: Overall, 30 patients (93.7%) were available for a mean follow-up of 28.8 months (12–46 mo) and had complete radiographic data. Their mean age was 45.1 years (32–58 y). At 3 years postoperatively, the success rate was 86.7% (26/30). After surgery, clinical parameters as Visual Analogue Scale score for back and leg pain, and ODI score showed statistically significant improvement (P<0.001), and the situation was well maintained during the follow-up time points. At 3 years postoperatively, the mean IDH at the index segment and upper and lower adjacent segments were 12.87, 12.61, and 11.62 mm, respectively, showing no significant difference compared with preoperative data (P1=0.0597, P2=0.6669, P3=0.9813). The ROM of the index and upper adjacent segment showed a slight but significant increase at the 3-year follow-up compared with baseline (P1=0.0128, P2=0.0007). The changes of ROM at the lower adjacent segment were not significant (P=0.6637). Tears of the iliac vein were observed in 2 patients. Prosthesis subsidence was observed in 3 patients (1 at 12 mo postoperatively, 1 at 24 mo postoperatively, and 1 at 32 mo postoperatively). Heterotopic ossification was observed in 1 patient at 36 mo postoperatively. At the 3-year follow-up, only 8 patients went back to their original work, and 15 patients changed jobs, whereas the last 7 patients stopped working. Conclusions: The 1- to 3-year follow-up of this cohort of patients showed satisfactory clinical outcomes. The IDHs at index and adjacent segments were well maintained after the surgery. The ROM at the lower adjacent segment remained unchanged, but the ROM at the index and upper adjacent segments showed a slight increase. The long-term results of activ L TDR was to be investigated.