Hounsfield unit of screw trajectory as a predictor of pedicle screw loosening after single level lumbar interbody fusion.

OBJECT: This study aims to clarify the clinical potential of Hounsfield unit (HU), measured on computed tomography (CT) images, as a predictor of pedicle screw (PS) loosening, compared to bone mineral density (BMD). METHODS: A total of 206 screws in 52 patients (21 men and 31 women; mean age 68.2 years) were analyzed retrospectively. The screws were classified into two groups depending on their screw loosening status on 3-month follow-up CT (loosening screw group vs. non-loosening screw group). Preoperative HU of the trajectory was evaluated by superimposing preoperative and postoperative CT images using three-dimensional image analysis software. Age, sex, body mass index, screw size, BMD of lumbar, and HU of screw trajectory were analyzed in association with screw loosening. Multivariate logistic regression analysis was performed, and the thresholds for PS loosening risk factors were evaluated using a continuous numerical variable and receiver operating characteristic (ROC) curve analyses. The area under the curve (AUC) was used to determine the diagnostic performance, and values > 0.75 were considered to represent good performance. RESULTS: The loosening screw group contained 24 screws (12%). Multivariate analysis revealed that the significant independent risk factors were not BMD but male sex [P = 0.028; odds ratio (OR) 2.852, 95% confidence interval (CI) 1.120-7.258] and HU of screw trajectory (P = 0.006; OR 0.989, 95% CI 0.980-0.997). ROC curve analysis demonstrated that the AUC for HU of screw trajectory for women was 0.880 (95% CI 0.798-0.961). The cutoff value was 153.5. AUC for men was 0.635 (95% CI 0.449-0.821), which was not considered to be a good performance. CONCLUSIONS: Low HU of screw trajectories was identified as a risk factor of PS loosening for women. For female patients with low HU, additional augmentation is recommended to prevent PS loosening.

Disseminated Penicillin-Resistant Streptococcus pneumoniae Infection: A Case Report.

An invasive pneumococcal disease involving sternoclavicular joint arthritis, lumbar spondylodiscitis, and muscular abscesses caused by penicillin-resistant Streptococcus pneumoniae has not been reported previously. We successfully treated a 57-year-old man with this condition using surgical drainage and debridement, and laminectomy/fenestration, in combination with the administration of two IV antimicrobial drugs based on blood culture results. Clinical resolution was obtained after decompression of the lumbar spine, with minimal restriction of the left lower limb. This treatment approach should be considered depending on the pathogen, underlying host factors, and the severity of the disease.

Bone tissue engineering with bone marrow-derived stromal cells integrated with concentrated growth factor in Rattus norvegicus calvaria defect model.

Concentrated growth factor (CGF) is an autologous leukocyte-rich and platelet-rich fibrin (L-PRF) biomaterial termed "second-generation platelet concentrate". CGF contains autologous osteoinductive platelet growth factors and an osteoconductive fibrin matrix. The purpose of this study was to assess the ability of CGF combined with bone marrow stromal cells (BMSCs) to heal critical-size rat calvaria defects in vivo and to modulate the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro. In the in-vivo study, the CGF group regenerated bone better than the control group, and combined therapy with CGF and BMSCs almost completely repaired critical-size bone defects within 12 weeks after surgery. In the in-vitro study, the CGF extract, at concentrations between 1 and 10%, promoted proliferation, osteogenic maturation, and mineralization of hTERT-E6/E7 human MSCs in a dose-dependent manner but had an inhibitory effect at higher concentrations. In conclusion, a CGF extract promoted the proliferation, osteogenic maturation, and mineralization of mesenchymal stem cells in vitro, and combination therapy with CGF and BMSCs resulted in excellent healing of critical-size bone defects in vivo.

Low incidence of adjacent segment disease after posterior lumbar interbody fusion with minimum disc distraction: A preliminary report.

STUDY DESIGN: A retrospective review of prospectively collected data. OBJECTIVE: To investigate the incidence of radiographic and symptomatic adjacent segment disease (ASD) and identify possible risk factors for ASD after posterior lumbar interbody fusion (PLIF) with minimum disc distraction by selecting low-height interbody cages. SUMMARY OF BACKGROUND DATA: Excessive disc space distraction is reportedly 1 of the risk factors for ASD after PLIF; however, the incidence and other risk factors of ASD after PLIF with minimum disc distraction remain unclear. METHODS: Forty-one consecutive patients who underwent PLIF at L4-L5 and were postoperatively followed up for a minimum of 2 years were included. The height and shape (box or bullet shape) of interbody cages was determined according to the disc height and morphology of the intervertebral space assessed on preoperative computed tomography scans to avoid excessive distraction. The incidence of radiographic and symptomatic ASD was evaluated and all demographic and radiographic parameters were compared between patients with and without ASD. Multivariate logistic regression analysis was performed to identify risk factors for ASD among the variables with P < .20 in univariate analysis. RESULTS: The overall incidence of ASD was 12.2% (5/41 patients): radiographic ASD, 7.3% (3 patients); symptomatic ASD, 4.9% (2 patients). Multivariate analysis revealed preoperative retrolisthesis of L3 on extension as the sole risk factor for ASD after PLIF with minimum disc distraction (odds ratio, 2.13; 95% confidence interval, 1.00-4.05; P = .049). CONCLUSIONS: The incidence of ASD in this study was lower than that of ASD in our previous study about PLIF with distraction of disc space (12.2% vs. 31.8%). Minimum disc distraction by selection of low-height interbody cages is a simple and effective method to prevent ASD at the surgeons' discretion, although preexisting retrolisthesis at the adjacent upper segment should be taken into consideration.

Risk Factors for Poor Patient-Reported Quality of Life Outcomes After Posterior Lumbar Interbody Fusion: An Analysis of 2-Year Follow-up.

STUDY DESIGN: A retrospective review of prospectively collected data. OBJECTIVE: The present study aimed to identify risk factors for poor patient-reported quality of life (QOL) outcomes, based on five categories (pain-related disorders, lumbar spine dysfunction, gait disturbance, social life dysfunction, and psychological disorders) of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), after posterior lumbar interbody fusion (PLIF) at the 2-year follow-up. SUMMARY OF BACKGROUND DATA: Many studies have been reported on patient QOL outcomes after lumbar surgery; however, few reports have focused on risk factors for poor postoperative QOL outcomes in terms of the various disabilities and dysfunctions after PLIF. METHODS: One hundred consecutive patients (39 men and 61 women; mean age 69.6 [44-84] yr) who underwent single- or two-level PLIF for degenerative spondylolisthesis and/or foraminal stenosis with a 2-year follow-up were included. The effectiveness of surgery in each category of the JOABPEQ was evaluated. Demographic and clinical data and radiographic parameters were reviewed. Risk factors for poor postoperative QOL outcomes in each category of the JOABPEQ were investigated by multivariate logistic regression analysis. RESULTS: Older age and spinopelvic malalignment (preoperative high pelvic tilt or postoperative decrease in lumbar lordosis [=postoperative increase in the mismatch between pelvic incidence and lumbar lordosis]) were risk factors for poor postoperative QOL outcomes in all categories of the JOABPEQ, except for lumbar spine dysfunction. In contrast, increase in number of PLIF segments, non-union, and radiographic adjacent segment degeneration were risk factors for poor postoperative QOL outcomes in lumbar spine dysfunction and gait disturbance. CONCLUSION: The risk factors for poor QOL outcomes after PLIF differed among the five categories of the JOABPEQ. In particular, surgery-related factors (e.g., increase in number of PLIF segments, nonunion, and radiographic adjacent segment degeneration) had a negative effect on the improvement of lumbar spine dysfunction and gait disturbance. LEVEL OF EVIDENCE: 4.

Intermittent administration of teriparatide enhances graft bone healing and accelerates spinal fusion in rats with glucocorticoid-induced osteoporosis.

BACKGROUND CONTEXT: There has been no study regarding the effect of intermittent administration of teriparatide (TPTD [recombinant human parathyroid hormone (1-34)]) on spinal fusion in patients with glucocorticoid-induced osteoporosis (GIOP). PURPOSE: To elucidate the effect of intermittent administration of TPTD on spinal fusion in rats with GIOP. STUDY DESIGN: An experimental animal study of rats under continuous glucocorticoid (GC) exposure undergoing spinal fusion surgery and administration of TPTD or saline. METHODS: Male 8-week-old rats (n=18) were administered 5 mg/kg methylprednisolone (MP) for 12 weeks. After 6 weeks of MP administration, the rats underwent posterolateral spinal fusion (L4-L5) with iliac crest autograft. Then, five times a week, they were given either saline or 40 µg/kg TPTD for 6 weeks. The following assessments were performed: time-course bone microstructural analysis of the fusion mass and adjacent vertebrae (L6), with in vivo microcomputed tomography (µCT); fusion assessment, with manual palpation testing and three-dimensional CT images; and bone histomorphometrical analysis of the fusion mass. RESULTS: In the TPTD group, values for bone volume and other bone microstructural parameters at the fusion mass increased and peaked 4 weeks after surgery, and these values were significantly greater than those for the control (CNT) group at 4 and 6 weeks after surgery. Fusion assessment showed that fusion rate was higher in the TPTD group than in the CNT group (CNT group: 56%, TPTD group: 89%). Bone histomorphometry revealed that values for bone formation parameters were significantly higher in the TPTD group than in the CNT group. CONCLUSIONS: Under continuous GC exposure in a rat model of spinal fusion, intermittent TPTD administration accelerated bone modeling and remodeling predominantly by stimulating bone formation at the fusion mass and increasing the fusion rate. Intermittent TPTD administration also improved bone microarchitecture of adjacent vertebrae.