负重位 CT 扫描在拇外翻中的作用。

The Role of Weightbearing Computed Tomography Scan in Hallux Valgus.

机构信息

Orthopaedic Foot and Ankle Surgery, University of Pennsylvania Health System, Philadelphia, PA, USA.

Musculoskeletal Radiology, Penn Medicine University City, Philadelphia, PA, USA.

出版信息

Foot Ankle Int. 2021 Mar;42(3):287-293. doi: 10.1177/1071100720962398. Epub 2020 Nov 4.

DOI:10.1177/1071100720962398

PMID:33148045

Abstract

BACKGROUND

Hyperpronation of the first metatarsal in hallux valgus (HV) is poorly understood by conventional weightbearing radiography. We aimed to evaluate this parameter using weightbearing computed tomography (WBCT) and to understand its association with other standard measurements.

METHODS

Retrospective evaluation of WBCT and weightbearing radiographs (WBXRs) was performed for 20 patients with HV feet and 20 controls with no such deformity. Axial computed tomography images of both groups were compared for the first metatarsal pronation angle (alpha angle) and tibial sesamoid subluxation (TSS) grades. The HV angle (HVA), first-second intermetatarsal angle (IMA), first metatarsal-medial cuneiform angle (MMCA), Meary's angle, and calcaneal pitch (CP) angle of the study and control groups were compared on both WBXR and the corresponding 2-dimensional images of WBCT. All measurements were independently performed by 1 musculoskeletal radiology fellow and 1 foot and ankle surgical fellow. Measurements were averaged and interobserver reliability was calculated.

RESULTS

The HV group demonstrated significantly higher values for TSS grade ( < .001) but not for alpha angle ( = .121) compared with controls. Likewise, significantly elevated HVA and IMA were noted in the HV group on both imaging modalities, while no such differences were observed for the CP angle. Higher MMCA and Meary's angle in the HV group were evident only on WBXR (MMCA, = .039; Meary's, = .009) but not on WBCT (MMCA, = .183; Meary's, .171).Among all, the receiver operating characteristic (ROC) curves demonstrated the greatest area under the curve (AUC) for HVA, followed by IMA. The alpha angle performed only just outside the range of chance (AUC, 0.65; 95% CI, 0.52-0.69). The Pearson's correlations of the alpha angle, in the HV group, revealed a significant linear relationship with TSS grade and with HVA on WBXR, and only trended toward a weak linear relationship with IMA and with HVA on WBCT.

CONCLUSION

The alpha angle, a measure of abnormal hyperpronation of the first metatarsal, was an independent factor that may coexist with other parameters in HV, but in isolation had limited diagnostic utility. "Abnormal" alpha angles were even observed in individuals without HV. Increases in IMA and MMCA were not necessarily associated with similar increases in alpha angle, despite moderate correlations with TSS grade and HVA on WBXR. Nevertheless, the WBCT was a useful method for assessing hyperpronation and guiding surgical management in individual cases.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

摘要

背景

传统负重位 X 线片对拇外翻（HV）中第一跖骨的过度旋前认识不足。我们旨在使用负重 CT（WBCT）评估该参数，并了解其与其他标准测量的关系。

方法

对 20 例 HV 足患者和 20 例无此类畸形的对照组患者进行了回顾性评估 WBCT 和负重 X 线片（WBXR）。比较两组的轴向 CT 图像以获得第一跖骨旋前角（alpha 角）和胫骨籽骨半脱位（TSS）分级。比较研究组和对照组的 HV 角（HVA）、第一二跖骨间角（IMA）、第一跖骨-内侧楔骨角（MMCA）、Meary 角和跟骨倾斜角（CP）在 WBXR 和相应的 WBCT 二维图像上的测量值。所有测量均由 1 名肌肉骨骼放射科医师和 1 名足踝外科医师独立进行。测量值取平均值并计算观察者间可靠性。

结果

HV 组的 TSS 分级明显高于对照组（<0.001），但 alpha 角无差异（=0.121）。同样，在两种成像方式上，HV 组的 HVA 和 IMA 值均明显升高，而 CP 角无差异。仅在 WBXR 上观察到 HV 组的 MMCA 和 Meary 角升高（MMCA，=0.039；Meary，=0.009），而在 WBCT 上则没有（MMCA，=0.183；Meary，=0.171）。在所有 ROC 曲线中，HVA 的曲线下面积（AUC）最大，其次是 IMA。alpha 角仅略高于机会范围（AUC，0.65；95%CI，0.52-0.69）。HV 组 alpha 角的 Pearson 相关性显示与 TSS 分级和 WBXR 上的 HVA 呈显著线性关系，仅与 IMA 和 WBCT 上的 HVA 呈弱线性关系。

结论

alpha 角，一种第一跖骨异常过度旋前的测量方法，是可能与 HV 中其他参数共存的独立因素，但单独使用时诊断效用有限。即使在没有 HV 的个体中，也观察到“异常”的 alpha 角。IMA 和 MMCA 的增加不一定与 alpha 角的增加相关，尽管与 WBXR 上的 TSS 分级和 HVA 有中度相关性。尽管如此，WBCT 仍然是评估旋前和指导个别病例手术治疗的有用方法。