Classification of the Kager fat pad and relationship between Kager fat pad and posterior ankle impingement syndrome

doi:10.13418/j.issn.1001-165x.2025.1.07

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Chinese Journal of Clinical Anatomy ›› 2025, Vol. 43 ›› Issue (1) : 40-44. DOI: 10.13418/j.issn.1001-165x.2025.1.07

Classification of the Kager fat pad and relationship between Kager fat pad and posterior ankle impingement syndrome

Zhang Lei^1,2,3, Tang Xiangyu⁴, Jiang Lu⁵, Yang Siyi⁵, Zhou Xin^1,2,3, Liu Tianyu⁴, Wang Guoyou^1,2,3*

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Abstract

Objective To classify the imaging morphologic features of the Karger fat pad (KFP) and to investigate its relationship with posterior ankle impingement syndrome (PAIS). Methods A total of 194 Chinese patients with ankle magnetic resonance imaging (MRI) scans between August 2018 and August 2021 were observed. Anatomical parameters included flexor hallucis longus-related length of KFP, KFP height, achilles-related length of KFP, the length of os trigonum, length of posterior inferior tibial process, the shortest distance between KFP and tibia, KFP sagittal area, and os trigonum-calcaneus-tibia angle were measured in T1-weighted MRI. Results A total of 194 subjects with os trigonum syndrome were enrolled in this study and there were 106 patients without PAIS (control group) and 88 patients with PAIS. KFP was categorized into 3 types based on its shape, length, height and sagittal area: type I (triangular), type II (long trapezoidal), type III (short trapezoidal). Among the three KFP types, Type Ⅲ (72, 81.8%) accounted for the greatest number in PAIS group, while Type Ⅰ (43, 40.6%) and Type Ⅱ (55, 51.9%) accounted for the larger proportion in the control group. Conclusion There is significant difference in the morphology of the KFP between individuals with and without PAIS. It is assumed that the change of KFP is crucial in the progression of PAIS, and a better understanding of different types of KFP is helpful to study the characteristics of PAIS, which can provide certain basis for clinical diagnosis of PAIS in the early stage.

Key words

Kager fat pad / / / Posterior ankle impingement syndrome / / / Os trigonum syndrome / / / Ankle / / / MRI

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Zhang Lei, Tang Xiangyu, Jiang Lu, Yang Siyi, Zhou Xin, Liu Tianyu, Wang Guoyou. Classification of the Kager fat pad and relationship between Kager fat pad and posterior ankle impingement syndrome[J]. Chinese Journal of Clinical Anatomy. 2025, 43(1): 40-44 https://doi.org/10.13418/j.issn.1001-165x.2025.1.07

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