Bacteriology of degenerated lumbar intervertebral disks.

STUDY DESIGN: A prospective microbiological analysis of intervertebral disk material in surgically treated patients presenting lumbar disk degeneration. OBJECTIVE: To determine the prevalence and species of bacteria in degenerated lumbar disks, their eventual role in the pathophysiology, and the possible influence of risk factors. SUMMARY OF BACKGROUND DATA: Intervertebral disk degeneration results from biochemical, mechanical, genetic, and toxic factors. The hypothesis of low-grade infection has been raised but not elucidated to date. METHODS: Eighty-three patients (34 males, 49 females, 41 y) were treated by lumbar disk replacement at L3-L4, L4-L5, or L5-S1. An intraoperative biopsy and microbiological culture were performed for each disk to determine if intradiskal bacteria were present. Magnetic resonance stages were Pfirrmann IV or V, with Modic I in 32, and Modic II in 25 cases. A preoperative discography was performed in 49 patients, 24 had previous nucleotomy. RESULTS: Bacteria were found in 40 disks, 43 cultures were sterile. The following bacteria were evidenced: Propionibacterium acnes 18, coagulase-negative staphylococci 16, gram-negative bacilli 3, Micrococcus 3, Corynebacterium 3, others 5. Ten biopsies presented 2 different species. Multinucleated cells were evidenced histologically in 33% of positive biopsies. Bacteria were predominantly found in males (P=0.012). The mostly positive level was L4-L5 (P=0.075). There was no significant relationship between bacterial evidence and Modic sign. A preoperative discography or previous nucleotomy did not represent significant contamination sources. None of the patients presented infectious symptoms. CONCLUSIONS: Although the hypothesis of biopsy contamination cannot be excluded, intradiskal bacteria might play a role in the pathophysiology of disk degeneration. However, the histologic presence of multinucleated cells may indicate an inflammatory process that could sustain the hypothesis of low-grade spondylodiscitis at 1 stage of the cascade of lumbar disk degeneration. These microbiological and histologic findings would need to be compared with nondegenerated disks. LEVEL OF EVIDENCE: : Diagnostic level III.

Influence of 2 different dynamic stabilization systems on sagittal spinopelvic alignment.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze and compare the sagittal spinopelvic alignment variation after implantation of purely dynamic and hybrid pedicle screw-based stabilization systems, seeking for its clinical implication. SUMMARY OF BACKGROUND DATA: Numerous studies have investigated the kinematic features of pedicle screw-based dynamic stabilization systems since their clinical application. However, there is a lack of literature concerning their influence on the sagittal spinopelvic alignment, which has been proved to be important in the development of future adjacent segment degeneration (ASD). METHODS: Lateral standing lumbar radiographs of 29 patients (17 males, 12 females, 27 to 64 y) who were implanted with purely dynamic (Dynesys: group A, n=15) or hybrid (FlexPLUS: group B, n=14) stabilization systems, and with a minimum follow-up of 1 year, have been reviewed. These parameters were measured using Spineview software and were compared within and between groups: L1 to S1 lordosis, lordosis of instrumented segments (ISL), cranial adjacent segment lordosis (CASL) next to the instrumentation, highest instrumented segment lordosis (HISL), pelvic incidence, sacral slope, and pelvic tilt. RESULTS: Preoperative lordosis parameters were not significantly different between group A and B. The average L1 to S1 lordosis decreased from 55.3 degrees preoperatively to 52.6 degrees postoperatively in group A (P=0.007) and from 60.2 degrees to 59.3 degrees in group B (P=0.054). There was no significant difference between both groups (P=0.083). The average ISL decreased from 25.9 degrees preoperatively to 21.7 degrees postoperatively (P=0.00002) in group A and from 30.0 degrees to 28.6 degrees in group B (P=0.153). The prepostoperative ISL variation was significantly different between group A and B (P=0.015). The average HISL decreased from 9.5 degrees to 6.2 degrees in group A (P=0.0007) and from 13.1 degrees to 12.4 degrees in group B (P=0.295). The loss of HISL was significantly greater (P=0.010) in group A than in group B. The average CASL increased from 6.9 degrees to 9.2 degrees (P=0.013) in group A. The CASL variation from 10.6 degrees to 10.4 degrees was not significant (P=0.763) in group B. When comparing both groups, the difference of CASL variation was statistically significant (P=0.043). The pelvic incidence, sacral slope, and pelvic tilt did not change significantly before and after instrumentation in both groups. CONCLUSIONS: On the basis of the result of this study, the hybrid stabilization system could better preserve the lordosis of instrumented segments and subsequently reduce the extent of compensatory lordosis increase at the cranial adjacent segment. This could theoretically prevent the development of an ASD. The long-term outcome and the correlation between lordosis-preserving capacity and ASD need to be further prospectively analyzed.

Thoracolumbar fractures surgically treated by "in situ contouring".

This is a retrospective study on a series of 70 patients with thoracolumbar fractures (TL), surgically treated by the in situ bending technique (ISB). Its purpose is to show the performances and limits of the ISB technique for the early correction of post-traumatic spine deformities as well as to estimate the overall outcome in this series and to discuss the indications for anterior grafting. Although the management of limbs fractures is a cleared issue today, spine fractures management is still a matter of debate. Surgical treatment progresses fast, while indications, the fixation techniques, fracture reduction options, and associated grafting are still blurry. Seventy patients with TL fractures, mean age 40.3 years (20-80) were treated by posterior fusion with a standard construct and deformity reduction by means of the ISB technique. Mean follow-up was 30.7 months (12-78). Pre- and post-operative deformity was evaluated and the relative deformity as defined by Farcy's sagittal index (SIF) was analyzed. Thirty-eight patients underwent anterior interbody grafting. The pre-operative SIF decreased from 16.98 to 1.62 degrees (15.36 degrees decrease). Eighty percent of patients were normo- or hyper-corrected. The loss of correction during the follow-up occurred within the disc (SIF: -2.24 degrees , vertebral kyphosis 0.94 degrees , p<0.001), and was lower in patients who underwent secondary anterior grafting (-5.21 degrees vs.-1.18 degrees , p=0.002). Clinical outcome is good (Oswestry=29.75) and seems to be better in cases of double approach (20.71 vs. 37.,4, p=0.001). Sepsis occurred in ten cases, and two patients experienced construct dismounting. One patient had a retroperitoneal hematoma that required embolization. Seventy-one percent of operated patients went back to their previous work after surgery. Spine fractures deserve an efficient treatment. The ISB technique improves post traumatic kyphosis. This results is maintained at long term if the posterior fusion is associated with anterior grafting in cases where the correction within the disc exceeds 50% of the total correction.