Ng Alvin C, Png Meng Ai, Mohan P Chandra, Koh Joyce S B, Howe Tet Sen
Department of Endocrinology, Singapore General Hospital, Singapore.
J Bone Miner Res. 2014 Mar;29(3):639-43. doi: 10.1002/jbmr.2078.
In 2010, the American Society for Bone and Mineral Research (ASBMR) task force defined major and minor features to assist in the case finding and reporting of atypical femoral fractures (AFFs). One major feature that was proposed was a "transverse or short oblique configuration." Our primary aim was to compare the conventional overall fracture morphology (OFM) with its associated angle (OFMA) and our proposed lateral cortical fracture angle (LCFA) in the assessment of fracture configuration in suspected AFFs and non-AFFs. The radiographs of 79 patients with AFFs and 39 patients with non-AFFs were each analyzed by two blinded reviewers to obtain the OFM, OFMA, and LCFA. Using the overall fracture morphology to assess the suspected AFFs resulted in discordance between reviewers in 18 cases (22.8%), of which 5 (6.3%) were discordant between short oblique (>30° to 60°) and long oblique (>60° to 90°) configurations, therefore affecting their classifications as AFFs. By assessing only the critical component within the lateral cortex, all the suspected AFFs fell well within the classification as transverse fractures with a mean LCFA of 4.8° (range 0.3 to 18.0, SD = 4.23). The inter-reader variability was also lower for LCFA versus OFMA (4.1° versus 6.9°, p = 0.001) when used to assess AFFs. Fracture angles were significantly different in AFFs versus non-AFFs regardless of whether the OFMA or LCFA methodology was employed, but the greater difference associated with LCFA suggests its greater discriminating power. When LCFA was used in conjunction with 0° to 30° as the criteria for transverse morphology, all the AFFs and non-AFFs were correctly classified. By using a standardized and precise method in measuring the fracture angle, specifically using only the component of the lateral cortex and limiting to truly transverse fractures, ie, between 0° and 30°, the LCFA is a robust and accurate method to assess the fracture morphology in suspected AFFs.
2010年，美国骨与矿物质研究学会（ASBMR）特别工作组定义了主要和次要特征，以协助发现和报告非典型股骨骨折（AFF）。其中一个提出的主要特征是“横行或短斜行形态”。我们的主要目的是在评估疑似AFF和非AFF的骨折形态时，比较传统的整体骨折形态（OFM）及其相关角度（OFMA）与我们提出的外侧皮质骨折角度（LCFA）。79例AFF患者和39例非AFF患者的X线片由两名不知情的阅片者分别进行分析，以获得OFM、OFMA和LCFA。使用整体骨折形态评估疑似AFF时，阅片者之间有18例（22.8%）存在不一致，其中5例（6.3%）在短斜行（>30°至60°）和长斜行（>60°至90°）形态之间存在不一致，从而影响了它们作为AFF的分类。通过仅评估外侧皮质内的关键部分，所有疑似AFF均符合横行骨折的分类，平均LCFA为4.8°（范围0.3至18.0，标准差=4.23）。在用于评估AFF时，LCFA的阅片者间变异性也低于OFMA（4.1°对6.9°，p=0.001）。无论采用OFMA还是LCFA方法，AFF与非AFF的骨折角度均有显著差异，但与LCFA相关的差异更大，表明其具有更大的鉴别能力。当将LCFA与0°至30°结合作为横行形态的标准时，所有AFF和非AFF均被正确分类。通过使用标准化且精确的方法测量骨折角度，特别是仅使用外侧皮质部分并限定为真正的横行骨折，即0°至30°之间，LCFA是评估疑似AFF骨折形态的一种可靠且准确的方法。
