PURPOSE To compare the performance of using Hounsfield units (HU) value derived from computed tomography and T-score of dual-energy X-ray absorptiometry (DXA) to predict pedicle screw loosening. METHODS We reviewed 253 patients aged ≥ 50 years undergoing pedicle screw fixation for lumbar degenerative diseases (LDD). The evaluation of screw loosening: radiolucent zones of ≥ 1 mm thick in X-ray. The criterion for osteoporosis: the lowest T-score ≤ - 2.5. The average HU value of L1-L4 was used to represent lumbar bone mineral density (BMD). The area under receiver operating characteristics curve (AUC) was used to evaluate the performance of predicting screw loosening. RESULTS One patient underwent reoperation for screw loosening at 9 months follow-up. At 12 months follow-up, the loosening rate was 30.6% (77/252) in the remaining 252 patients. Osteoporotic patients had higher loosening rate than non-osteoporotic patients (39.3% vs. 25.8%, P = 0.026). The T-score showed no significant difference between loosening group and non-loosening group (- 2.1 ± 1.5 vs. - 1.7 ± 1.6, P = 0.074), and so is the lowest lumbar BMD of DXA (0.83 ± 0.16 g/cm2 vs. 0.88 ± 0.19 g/cm2, P = 0.054). The HU value was lower in the loosening group (106.8 ± 34.4 vs. 129.8 ± 45.7, P < 0.001). The HU value (OR, 0.980; 95%CI 0.968-0.993; P = 0.002) was the independent influencing factor of screw loosening. The AUC of predicting screw loosening was 0.666 (P < 0.001) for HU value and 0.574 (P = 0.062) for T-score. CONCLUSIONS HU value is a better predictor of pedicle screw loosening than T-score of DXA in patients aged ≥ 50 years with LDD. We should not only focus on the DXA measurements when making surgical plans concerning lumbar fixation. These slides can be retrieved under Electronic Supplementary Material.

中文翻译：

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在腰部退行性疾病患者中，Hounsfield单位值比DXA的T评分更好地预测椎弓根螺钉松动。

目的比较使用计算机断层扫描和双能X线骨密度仪（DXA）的T分数得出的Hounsfield单位（HU）值预测椎弓根螺钉松动的性能。方法我们回顾了253名年龄≥50岁的患者接受了椎弓根螺钉固定治疗腰椎退行性疾病（LDD）。螺钉松动的评估：X射线中≥1毫米厚的射线可透区域。骨质疏松的标准：最低T分数≤-2.5。L1-L4的平均HU值用于表示腰椎骨矿物质密度（BMD）。接收器工作特性曲线下的面积（AUC）用于评估预测螺丝松动的性能。结果一名患者在9个月的随访中因螺钉松动而接受了再次手术。随访12个月，其余252例患者的松动率为30.6％（77/252）。骨质疏松患者的松动率高于非骨质疏松患者（39.3％比25.8％，P = 0.026）。T评分显示松动组和非松动组之间无显着差异（-2.1±1.5 vs.-1.7±1.6，P = 0.074），DXA的最低腰椎骨密度（0.83±0.16 g / cm2 vs 0.88±0.19 g / cm2，P = 0.054）。松动组的HU值较低（106.8±34.4 vs. 129.8±45.7，P <0.001）。HU值（OR，0.980； 95％CI 0.968-0.993； P = 0.002）是螺钉松动的独立影响因素。对于HU值，预测螺钉松动的AUC为0.666（P <0.001），对于T值，预测为0.574（P = 0.062）。结论在LDD≥50岁的患者中，HU值比DXA的T评分更好地预测了椎弓根螺钉松动。在制定有关腰椎固定的手术计划时，我们不仅应专注于DXA测量。这些幻灯片可以在电子补充材料下找到。