Last revised by Daniel J Bell on 3 Jul 2023

An enthesis (plural: entheses), also known, more informally, as a footprint, generally refers to the anatomic junction where connective tissue (e.g. ligament, tendon, joint capsule, bursa or a combination thereof) attaches to bone.

Entheses are commonly classified into two types 1:

  • fibrous

  • fibrocartilage



In a fibrous enthesis, the collagen fibers comprising ligament or tendon attach directly to periosteum or bone cortex 1,2. They are usually associated with short tendons, e.g. gluteus maximus insertion onto the femur 1. This usually occurs along a relatively wide area of a bone shaft 1.


A fibrocartilage enthesis represent a more complex attachment between tendon and bone. They generally occur at locations where tendon inserts onto a portion of bone lacking periosteum, e.g. an epiphysis.

They are classically divided into four zones:

  1. collagen zone - derived from tendon or other soft tissue structure

  2. non-calcified fibrocartilaginous zone - variable thickness where chondrocytes predominate

  3. calcified fibrocartilaginous zone - an abrupt transition ("tidemark" or "blue line")

  4. subchondral bone zone

The zonal organization is thought to result in decreased stress on the interface 1.

Related pathology

  • enthesopathy: a pathological condition affecting the enthesis

  • enthesitis: an inflammatory condition causing enthesopathy

  • enthesophyte: bony projection at an enthesis in response to enthesopathy

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