The accuracy with which the head and spine could be positioned in the frontal and sagittal planes relative to the pelvis was measured and compared in ten healthy adult males. Subjects were tested with eyes closed, while standing with their pelvis externally restrained. The positions of markers, attached to the back of the head and over each of the T1, T6, T11, and L3 spinous processes, were measured to the nearest mm using strain-gaged flexible beam transducers. Subjects were tested for their accuracy in sensing return of the trunk to an initial neutral position under different test conditions. Results showed that positioning was 16-45% more accurate in the frontal than in the sagittal plane, although the difference did not reach statistical significance. T1 could be centered to within 7 and 10 mm in the frontal and sagittal planes, respectively. No significant differences were found between active and passive positioning accuracies. Presence of an external trunk moment did not significantly affect trunk positioning accuracy, although it systematically caused overshoot of the neutral position. Lastly, lateral trunk shifts exceeding 12 mm may be classified as abnormal in young adults.
This paper reports myoelectric activity measurements in the lumbar trunk muscles when subjects performed tasks involving various degrees of lateral bending. Biomechanical model analyses were made to estimate the tensions in the lumbar trunk muscles required to perform those tasks. The tensions and the activity measurements were compared to see if a muscle relaxation phenomenon occurred. A relaxation phenomenon in the erector spinae muscles was observed to occur in quiet standing in a laterally-bent position of the trunk, qualitatively similar to the flexion-relaxation phenomenon reported by Schultz et al. in 1985(13). However, no relaxation was observed to occur in the lateral oblique abdominal muscles in laterally-bent postures of the trunk.
had negative margins, and 37 had positive margins. When used, the median dose for adjuvant radiation was 60 Gy (range 48-70.4 Gy). Compared to negative margins, NAAE margins were associated with having a T3-4 stage, an N2-3 stage, ECE, PNI, a larger depth of invasion, and adjuvant radiation/chemoradiation. For patients with negative, NAAE, and positive margins, the 2-year estimates of LRR were 27%, 36%, and 47% (pZ0.06), and 2-year estimates of PFS were 65%, 50%, and 22% (p<0.001). On multivariate analysis, compared to NAAE margins, positive margins had a trend for worse LRR (HR 2.35, pZ0.13) and inferior PFS (HR 2.10, pZ0.0008); whereas outcomes were more favorable for negative margins but not statistically significant (LRR HR 0.83, pZ0.34; PFS HR 0.85, pZ0.32). Similar results were seen for patients with adverse risk features who received adjuvant radiation for negative compared to NAAE margins (LRR HR 0.70, pZ0.22; PFS HR 0.74, pZ0.20). Conclusion: Our institutional experience indicates that there may be a benefit to having negative margins of the initial specimen compared to margins that are NAAE. Positive margins for patients with OCSCC are associated with inferior outcomes.
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