The Kager\u2019s fat pad radiological anatomy revised

Paweł Szaro,Mateusz Polaczek,Bogdan Ciszek

doi:10.1007/s00276-020-02552-1

Abstract

PurposeThe aim of the study was to map connections within the Kager’s fat pad between the structures which limit it.MethodsA retrospective re-review of 200 ankle magnetic resonance imaging (MRI) examination was conducted. Connections within the Kager’s fat pad between the superior peroneal retinaculum, the fibulotalocalcaneal ligament, the posterior talocalcaneal ligament, the flexor hallucis longus, the paratenon of the Achilles tendon, the flexor retinaculum and bones were studied and a model of the connections was constructed.ResultsThe superior peroneal retinaculum was directly connected with the fibulotalocalcaneal ligament in 85.5% of cases, the lateral part of the paratenon in 82.5%, the processus posterior tali in 78.5%, the posterior talofibular ligament in 32%, the flexor retinaculum in 29.5% and the anterior talofibular ligament in 9%.The fibulotalocalcaneal ligament was connected with the paratenon (on the medial side 88.5%, on the lateral side 68.5%), the flexor retinaculum in 70%, the posterior process of the talus in 79%, the osteofibrosus tunnel for the flexor hallucis longus in 53%, the posterior talofibular ligament in 43.5% and the calcaneofibular ligament in 10.5%.The posterior talocalcaneal ligament was connected with the fibulotalocalcaneal ligament in 71%, with the osteofibrosus tunnel for the flexor hallucis longus in 76.5%, with the flexor retinaculum in 70%. The plantaris tendon showed projection to the crural fascia in 34 of % cases.ConclusionIn the Kager’s fat pad there are present more connections than previously reported. All the connections unit at the level of the posterior process of the talus.

Highlights

Connections within the Kager’s fat pad (KFP) have not been comprehensively studied
The KFP is an adipose structure located between the Achilles tendon, the flexor hallucis longus (FHL) and the calcaneus [8, 28]
Most of the connections we have found are projections of the crural fascia orientated in the frontal plane, their assessment in the horizontal plane is the most optimal

Summary

Introduction

Connections within the Kager’s fat pad (KFP) have not been comprehensively studied. The KFP is an adipose structure located between the Achilles tendon, the flexor hallucis longus (FHL) and the calcaneus [8, 28]. The relatively large size of the KFP enables its individual parts to have different functions and exhibit slightly different. Only two connections have been found within the KFP: the posterior talocalcaneal ligament (PTCL) and the fibulotalocalcaneal ligament (FTCL) [6, 19]. The PTCL originates on the lateral tubercle on the posterior process of the talus and inserts on the superior outline of the calcaneus [6]. The FTCL originates in the anterior part of the malleolar groove, runs medially, divides into flat sheet-like laminas, the superomedial and the inferolateral. The first one inserts onto the lateral tubercle while the second one inserts onto the superior outline of the calcaneus [19]. The one which inserts onto talus is sometimes called horizontal or talar, while the one which runs toward the calcaneus, inferolateral or peroneocalcaneal [20]

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