Appreciate the importance of recognising the presence of normal communication between ankle joint and flexor hallucis longus (FHL) tendon sheath Become familiar that pathologies commencing in the ankle joint can manifest in the FHL tendon sheath on imaging Learn the imaging spectrum of loose bodies in the FHL tendon sheath
Background Communication between the flexor hallucis longus (FHL) tendon sheath and the ankle joint is well-recognised,
and is reportedly present in around 17% of individuals.(1) However,
migration of osteochondral loose bodies from the ankle joint into the FHL tendon sheath is not a well-recognised phenomenon,
with only one case described in the radiology literature so far.(2) We hereby discuss the aetiologies of loose bodies and discuss their locations within the FHL tendon sheath.
Imaging findings OR Procedure Details
Origin of loose bodies Intra-articular loose bodies can result as sequelae of a wide range of pathologies,
neuropathic arthropathy and inflammation. These can migrate from the ankle joint into the FHL tendon sheath.
The concept of migration between compartments is established and is well-documented particularly between knee joint with popliteal cyst,
hip joint with iliopsoas bursa and more.(3,4) Floating fat in the FHL tendon sheath having migrated from the...
Conclusion/Take homepoints Be aware of loose body migrating from the ankle joint into the FHL tendon sheath.
Presence of FHL tendon sheath loose bodies should prompt a closer assessment of the ankle joint itself for any pathologies. Be wary not to misdiagnose loose bodies in the FHL tendon sheath as primary chondromatosis.
This may change surgical management,
especially given the potential,
albeit low risk of malignant transformation. Misdiagnosis of loose bodies as lipoma or myositis...
The flexor hallucis longus: tenographic technique and correlation of imaging findings with surgery in 39 ankles.
2005;236(3):974-82. Shah A,
Flexor Hallucis Longus Loose Bodies- An Unusual Cause of Plantar Midfoot Pain2013. Froelich JM,
Symptomatic loose bodies of the knee located in a popliteal cyst.
2009;32(12):918. Kim SH,
Dr Jenn S Wong Musculoskeletal Radiology Fellow The Robert Jones and Agnes Hunt Orthopaedic Hospital