Less cellular than its uncalcified counterpart, this zone has an extracellular matrix that is calcified. The direct continuity between plantar fascia and Achilles tendon that is characteristic of the adult reflects the initial attachment of both structures to the calcaneal perichondrium rather than to the skeletal anlagen itself.
Consequently, they are commonly subject to overuse injuries enthesopathies that are well documented in a number of sports. It is noteworthy that disease in spondyloarthritis is virtually restricted to fibrocartilaginous entheses, and thus they alone are considered in more detail.
This particular anatomic and functional unit is an example of what has been termed a synovio-entheseal complex and is key to understanding why enthesitis and synovitis may be intimately linked Fig. Tendon or ligament- immediately adjacent to the attachment site- The bone and tendon surfaces adjacent to the enthesis are lined by fibrocartilage.
The fibrocartilage is also avascular, and the blood supply of the enthesis is derived largely from vessels in the peritenon and adjacent Enthesis organ anatomy marrow. Consequently, the immediately adjacent part of the tendon is compressed against the superior tuberosity of the calcaneus.
Enthesis Organ components The underlying bone - insertions are anchored to the bone like the roots of a tree are anchored to the ground. Neither do we know the relationship between the development of the Achilles tendon enthesis organ and that of the plantar fascia.
All sections had been cut in the sagittal plane, except for the mm fetus, where the sections had Enthesis organ anatomy cut coronally. From the earliest stages, it was evident that the Achilles tendon and plantar fascia had a mutual attachment to the calcaneal perichondrium.
Four zones of tissue are typically recognized at such attachment sites: The adjacent bone surfaces- Insertions may run over bony prominences termed tuberosities.
At such locations there is contact between hard and soft tissues but no anchorage as at entheses themselves. Basic mechanical engineering principles would suggest that a tendon that kinks under load would be more liable to failure.
A straight interface called the tidemark separates calcified from uncalcified fibrocartilage and is the mechanical boundary between hard and soft tissues.
The former are fibrocartilaginous and the latter are fibrous. In contrast, fibrocartilaginous entheses are characteristic of tendons and ligaments attached to epiphyses and apophyses, where the insertional angle of the tendon or ligament relative to the bone changes throughout the range of joint movement.
Indeed, the cortex can be focally absent at microscopic sites. The gradual rather than abrupt bending of the soft tissues of entheses close to joint margins, which is a consequence of matrix stiffening by proteoglycans in enthesis fibrocartilage, dissipates stress concentration at the attachment site.
These authors based their classification system on the location of entheses associated with long bones, i. This is damaging to the floor in comparison to a broad based cushioned sole of a running shoe. It is stress concentration at the hard—soft tissue interface which makes entheses vulnerable to acute or overuse injuries in sport.
Purpose of the enthesis organ If all of the stressing was concentrated at the attachment point to bone lots of damage would occur. Briefly, the fat pad is thought to facilitate the movement of tendon relative to bone, prevent tendon—bone adhesion, aid in the spread of bursal fluid and act as a space filler and immune organ Theobald et al.
This is a diagram of the Achilles tendon enthesis organ. The insertions of deltoid and pronator teres muscles are good examples.
The enthesis is closely integrated into the bone. The first components of the enthesis organ to appear in the mm foetus were the retrocalcaneal bursa and the crural fascia. There are two major types: Entheses are often regarded as being well supplied with pain and proprioceptive receptors.However, it is increasingly recognised that in many cases the enthesis is really just part of an enthesis organ.
An organ is a group of related tissues that function together to carry out a specific task. Enthesis organs exist where the part of the tendon or ligament adjacent. What is Enthesopathy? Enthesis Anatomy; Causes.
Spondyloarthropathies. Ankylosing Spondylitis; Reactive arthritis; Enthesis Anatomy. Entheses are part of an organ named as enthesis organ. In defining an organ, it is a group of tissues functioning together to perform specific tasks.
So, enthesis organis are found in regions where. Where tendons and ligaments meet bone: attachment sites (‘entheses’) in relation to exercise and/or mechanical load The application of the ‘enthesis organ’ concept (a collection of tissues adjacent to the enthesis itself, which jointly serve the common function of stress dissipation) to understanding enthesopathies is considered and.
The function of the enthesis organ is to provide a stable anchorage to the skeleton and to minimise damage at the insertion site which is subject to high levels of physical stress. The enthesis organ. The enthesis organ is composed of the enthesis insertion and adjacent tissues.
The enthesis organ consists of the enthesis itself (at the base of the distal phalanx), sesamoid fibrocartilage in the deep surface of the extensor tendon, articular cartilage on the head of the intermediate phalanx (IP), and the intervening joint cavity (asterisk).
The attachment of the Achilles tendon is part of an ‘enthesis organ’ that reduces stress concentration at the hard–soft tissue interface. The organ also includes opposing sesamoid and periosteal fibrocartilages, a bursa and Kager's fat pad.Download