While anteroposterior instability of spinal segments is regarded as an important biomechanical aspect in the clinical evaluation of lumbar pathologies, the reliability of the available diagnostic tools is limited and an intraoperative method to quantify stability is lacking. The aim of this study was to develop and validate an instrument to measure the anteroposterior stability of a spinal segments in real-time.
MethodsTorsi of five fresh-frozen human cadavers were used for this study. After pedicle screw insertion, a specifically modified reposition tool composed with load and linear sensors was used to measure the segmental anteroposterior motion caused by 100 N anterior and posterior force during 5 loading cycles on either side of the instrumentation by two different operators. The spinal segments were then resected from the torsi and anteroposterior loading with ± 100 N was repeated in an advanced biomechanical spine testing setup as a reference measurement. The Inter-correlation coefficient (ICC) was used for validation of the “intraoperative” device.
ResultsInter-operator repeatability of the measurements showed an ICC of 0.93 (p < 0.0001) and the bilateral (left–right) comparison had an ICC of 0.73 (p < 0.0001). The ICC resulting from the comparison to the reference measurement was 0.82 (p < 0.0001) without offset correction, and 0.9 (p < 0.0001) with offset correction. The ICC converged at this value already after two of the five performed loading cycles.
ConclusionAn accurate and reliable measurement tool is developed and validated for real-time quantification of anteroposterior stability of spinal segments and serves as a basis for future intraoperative use.
相似文献To compare the residual range of motion (ROM) of cortical screw (CS) versus pedicle screw (PS) instrumented lumbar segments and the additional effect of transforaminal interbody fusion (TLIF) and cross-link (CL) augmentation.
MethodsROM of thirty-five human cadaver lumbar segments in flexion/extension (FE), lateral bending (LB), lateral shear (LS), anterior shear (AS), axial rotation (AR), and axial compression (AC) was recorded. After instrumenting the segments with PS (n = 17) and CS (n = 18), ROM in relation to the uninstrumented segments was evaluated without and with CL augmentation before and after decompression and TLIF.
ResultsCS and PS instrumentations both significantly reduced ROM in all loading directions, except AC. In undecompressed segments, a significantly lower relative (and absolute) reduction of motion in LB was found with CS 61% (absolute 3.3°) as compared to PS 71% (4.0°; p = 0.048). FE, AR, AS, LS, and AC values were similar between CS and PS instrumented segments without interbody fusion. After decompression and TLIF insertion, no difference between CS and PS was found in LB and neither in any other loading direction. CL augmentation did not diminish differences in LB between CS and PS in the undecompressed state but led to an additional small AR reduction of 11% (0.15°) in CS and 7% (0.05°) in PS instrumentation.
ConclusionSimilar residual motion is found with CS and PS instrumentation, except of slightly, but significantly inferior reduction of ROM in LB with CS. Differences between CS and PS in diminish with TLIF but not with CL augmentation.
相似文献Purpose
The aim of this study was to identify modifications in health, economic and social determinants of quality of life (QoL) in community-dwelling older adults when using different cut-offs to defining favorable QoL.Methods
Data of year 2011 annual assessment in 1003 older men and women from the Lc65+ cohort study were used. Overall QoL was self-rated as ‘excellent,’ ‘very good,’ ‘good,’ ‘fair,’ or ‘poor.’ To identify significant health (self-rated health, SF-12v2 physical and mental health), economic (financial situation), and social (living with others, being socially supported, emotional support, group activities participation) determinants of QoL, a cut-off was set at three different positions to define favorable QoL on the ‘excellent’ to ‘poor’ spectrum: at least ‘good’ (model 1); at least ‘very good’ (model 2); and ‘excellent’ only (model 3).Results
In all three models, bivariable analyses indicated significant associations between QoL and at least one variable from each health, economic, and social dimension. In multivariable analyses, only health-related variables remained significantly associated with QoL in model 1. Model 3 additionally retained financial situation. In model 2, QoL was positively associated with physical health [odds ratio (OR) 1.10, p < 0.001], mental health (OR 1.12, p < 0.001), self-rated health (OR 2.43, p < 0.001), group activities participation (OR 1.43, p = 0.037), being socially supported (OR 1.58, p = 0.024), and not reporting financial difficulties (OR 1.76; p = 0.036).Conclusions
Using different cut-offs to defining favorable QoL results in important changes in the number and type of significant health, economic and social determinants. A cut-off between ‘good’ and ‘very good’ appears to best reflect the multidimensional nature of QoL.To elucidate residual motion of cortical screw (CS) and pedicle screw (PS) constructs with unilateral posterior lumbar interbody fusion (ul-PLIF), bilateral PLIF (bl-PLIF), facet-sparing transforaminal lumbar interbody fusion (fs-TLIF), and facet-resecting TLIF (fr-TLIF).
MethodsA total of 35 human cadaver lumbar segments were instrumented with PS (n = 18) and CS (n = 17). Range of motion (ROM) and relative ROM changes were recorded in flexion/extension (FE), lateral bending (LB), axial rotation (AR), lateral shear (LS), anterior shear (AS), and axial compression (AC) in five instrumentational states: without interbody fusion (wo-IF), ul-PLIF, bl-PLIF, fs-TLIF, and fr-TLIF.
ResultsWhereas FE, LB, AR, and AC noticeably differed between the instrumentational states, AS and LS were less prominently affected. Compared to wo-IF, ul-PLIF caused a significant increase in ROM with PS (FE + 42%, LB + 24%, AR + 34%, and AC + 77%), however, such changes were non-significant with CS. ROM was similar between wo-IF and all other interbody fusion techniques. Insertion of a second PLIF (bl-PLIF) significantly decreased ROM with CS (FE -17%, LB -26%, AR -20%, AC -51%) and PS (FE − 23%, LB − 14%, AR − 20%, AC − 45%,). Facet removal in TLIF significantly increased ROM with CS (FE + 6%, LB + 9%, AR + 17%, AC of + 23%) and PS (FE + 7%, AR + 12%, AC + 13%).
Conclusionbl-PLIF and TLIF show similarly low residual motion in both PS and CS constructs, but ul-PLIF results in increased motion. The fs-TLIF technique is able to further decrease motion compared to fr-TLIF in both the CS and PS constructs.
相似文献