Abstract: Objective　To analyze the value of metatarsal cortical index (MCI) in the diagnosis of metatarsal stress fractures. Methods　Forty-one patients with metatarsal stress fracture who were treated in Xianning Central Hospital from January 2019 to October 2021 were selected as an experimental group, including 26 males and 15 females, and they were (36.2±8.9) years old; 41 healthy people matched by age and gender in the experimental group were selected as a control group during the same period, including 25 males and 16 females, and they were (34.9±9.7) years old. The clinical data, propeptide of type Ⅰ procollagen (PINP), type I collagen cross-linked C-terminal telopeptide (CTX-I), 25-hydroxyvitamin D[25-(OH)D], and MCI were compared between these two groups. t test was used for the measurement data, and chi square test for the enumeration data. Results　The bone mineral density (BMD) of the experimental group was smaller than that of the control group (t=-2.043, P<0.05). The levels of CTX-I in the experimental group were higher than that in the control group (t=3.670, P<0.05). The levels of PINP and 25(OH)both in the experimental group were lower than those in the control group (t=-2.164 and -2.075, all P<0.05). The MCI's of all the metatarsals in the experimental group were lower than those in the control group (t=-2.062, -2.019, -2.012, -5.889, and -2.083; all P<0.05). The results of Spearman correlation analysis showed that each MCI was positively correlated with metatarsal stress fractures. Multivariate logistic regression analysis showed that CTX-I (OR=6 065.508, P=0.021) was an independent risk factor for metatarsal stress fractures, while MCI Ⅳ(OR=0.011, P=0.001) was a protective factor for metatarsal stress fractures. The areas under the receiver operating characteristic curve (ROC) (AUC) of CTX-I and MCI Ⅳ in the diagnosis of metatarsal stress fractures were 0.825 (95%CI 0.735-0.914) and 0.869 (95%CI 0.793-0.945). The optimal cutoff values of CTX-I and MCI IV were 0.34 ng/ml and 1.7%. The diagnostic sensitivities of CTX-I and MCI IV were 66% and 81%, and the diagnostic specificities of CTX-I and MCI IV were 83% and 85%. Conclusions　CTX-I and MCI IV are the influencing factors of metatarsal stress fracture, and can be used as important indicators in the diagnosis of metatarsal stress fracture.

Key words: Metatarsal cortical index, Metatarsal stress fracture, Type I collagen cross-linked C-terminal peptide, 25-hydroxyvitamin D, Receiver operating characteristic curve

摘要： 目的　探讨跖骨皮质指数（MCI）对跖骨应力性骨折的临床诊断价值。方法　选取2019年1月至2021年10月于咸宁市中心医院进行治疗的41例跖骨应力性骨折患者作为试验组，其中男26例，女15例，年龄（36.2±8.9）岁；选取同时期41例健康人作为对照组，其中男25例，女16例，年龄（34.9±9.7）岁。对比两组患者临床资料、Ⅰ型氨基端延长肽（PINP）、Ⅰ型胶原交联羧基末端肽（CTX-Ⅰ）和25-羟维生素D［25-（OH）D］、跖骨皮质指数（MCI Ⅰ～MCI Ⅴ），计量资料采用t检验，计数资料采用卡方检验。结果　试验组骨密度（BMD）小于对照组（t=-2.043，P<0.05），试验组CTX-Ⅰ水平高于对照组（t=3.670，P<0.05），试验组PINP、25（OH）D水平均低于对照组（t=-2.164、-2.075，均P<0.05），试验组第一脚跖骨MCI（MCI Ⅰ）、第二脚跖骨MCI（MCI Ⅱ）、第三脚跖骨MCI（MCI Ⅲ）、第四脚跖骨MCI（MCI Ⅳ）、第五脚跖骨MCI（MCI Ⅴ）均小于对照组（t=-2.062、-2.019、-2.012、-5.889、-2.083，均P<0.05）。Spearman相关性分析结果显示，每个跖骨皮质指数与跖骨应力性骨折均呈正相关。多因素logistic回归分析结果显示，CTX-I为跖骨应力性骨折的独立危险因素（OR=6 065.508，P=0.021），而MCI Ⅳ为跖骨应力性骨折的保护性因素（OR=0.011，P=0.001）。CTX-Ⅰ和MCI Ⅳ诊断跖骨应力性骨折的受试者工作特征曲线（ROC）、曲线下面积（AUC）分别为0.825（95%CI 0.735～0.914）和0.869（95%CI 0.793～0.945），CTX-Ⅰ和MCI Ⅳ的最佳截点值（cutoff值）分别为0.34 μg/L和1.7%，CTX-Ⅰ和MCI Ⅳ的诊断敏感度分别为66%和81%，CTX-Ⅰ和MCI Ⅳ的诊断特异度分别为83%和85%。结论　CTX-I和MCI Ⅳ为应力性骨折的影响因素，CTX-Ⅰ和MCI Ⅳ可作为诊断跖骨应力性骨折的重要指标。

关键词: 跖骨皮质指数, 跖骨应力性骨折, Ⅰ型胶原交联羧基末端肽, 25-羟维生素D, 受试者工作曲线