Reduced Bone Density Based on Hounsfield Units After Long-Segment Spinal Fusion with Harrington Rods
Long-segment instrumentation, such as Harrington rods, offloads vertebrae within the construct, which may result in significant stress shielding of the fused segments. The present study aimed to determine the effects of spinal fusion on bone density by measuring Hounsfield units (HUs) throughout the...
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Veröffentlicht in: | World neurosurgery 2024-05, Vol.185, p.e509-e515 |
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Zusammenfassung: | Long-segment instrumentation, such as Harrington rods, offloads vertebrae within the construct, which may result in significant stress shielding of the fused segments. The present study aimed to determine the effects of spinal fusion on bone density by measuring Hounsfield units (HUs) throughout the spine in patients with a history of Harrington rod fusion.
Patients with a history of Harrington rod fusion treated at a single academic institution were identified. Mean HUs were calculated at 5 spinal segments for each patient: cranial adjacent mobile segment, cranial fused segment, midconstruct fused segment, caudal fused segment, and caudal adjacent mobile segment. Mean HUs for each level were compared using a paired-sample t test, with statistical significance defined by P < 0.05. Hierarchic multiple regression, including age, gender, body mass index, and time since original fusion, was used to determine predictors of midfused segment HUs.
One hundred patients were included (mean age, 55 ± 12 years; 62% female). Mean HUs for the midconstruct fused segment (110; 95% confidence interval [CI], 100–121) were significantly lower than both the cranial and caudal fused segments (150 and 118, respectively; both P < 0.05), as well as both the cranial and caudal adjacent mobile segments (210 and 130, respectively; both P < 0.001). Multivariable regression showed midconstruct HUs were predicted only by patient age (−2.6 HU/year; 95% CI, −3.4 to −1.9; P < 0.001) and time since original surgery (−1.4 HU/year; 95% CI, −2.6 to −0.2; P = 0.02).
HUs were significantly decreased in the middle of previous long-segment fusion constructs, suggesting that multilevel fusion constructs lead to vertebral bone density loss within the construct, potentially from stress shielding. |
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ISSN: | 1878-8750 1878-8769 1878-8769 |
DOI: | 10.1016/j.wneu.2024.02.063 |