More info about the enthesis

Since the new proposed LSJL modality, involves loading sites where bones attach to each other specifically at the enthesis, due to the similarity of the enthesis of the zone of ranvier which is where the pool of stem cells resides to help formulate the growth plate.

Here’s some images and quotations from the orthopaedics blog:

Note although this article mainly refers to tendon enthesis, a majority of the info should apply to ligament enthesis(which tend to be attached closer to the regions near where the growth plate used to be).

tendon enthesis

This next image shows in much more detail into how the enthesis really integrates into the bone and how enthesis stem cells could be stimulated to form a mini growth plate.  Bone erosion could occur allowing this growth plate to extend across the bone.  In fact, in arthritis which is associated with thickening of the enthesis’ bone erosion does occur.:

detailed view tendo enthesis
Note how the mineralized fibrocartilage integrates into the bone.  The thickening of the enthesis and the erosion of bone in some forms of arthritis, I could only find citations of it occuring in tendons and have not found instances of it resulting in increased length.  But that is likely a result of tendons being more subject to mechanical loading and this new method of LSJL being a novel way to mechanical load the ligaments.  Also ligaments in contrast to tendons are in a better position to contribute to longitudinal bone growth.  In fact, most of the studies I could find on mechanical loading on ligaments referred to loading on the ligament cells themselves rather than loading of the ligaments in the body.

Ligament injuries tend to occur due to heavy impact or overstretching of the ligament.  Pressing of the bones against each other is not a common way of ligament injury indicating that this method of LSJL loading is in fact a novel way of loading the ligaments.

“There is physiological thickening of the fibrocartilage with stress.”<-This tends to happen more with tendons as they are attached to muscle but with LSJL we can encourage it to happen at the ligament fibrocartilage.

” there are other components adjacent to the enthesis proper which also share the stress forces and are termed the “Enthesis organ”. These include the Periosteal fibrocartilage, the Sesamoid fibrocartilage, the Fat pad and Bursa. The Synovial entheseal complex is a concept that the adjacent bursa or joint lining share stress forces, especially compressive forces and are an integral part of the enthesis organ”<-These will be different for the ligament.

Here’s some info from another site that could be pertinent:

Bone Erosion at Normal Insertions

“Bone erosion is a process whereby the surface of a bone (the bone cortex) is degraded or eroded and is most typically seen in the setting of inflammation. However, the normal skeleton appears to be riddled with microscopic erosions. The enthesis is a highly mechanically stressed site which leads to microtrauma to the immediately adjacent bone. This is the basis for small erosions in the normal non-diseased skeleton which likely repair spontaneously.”<-Can we cause sufficient bone erosion as to allow for a new growth plate?

“The early phases of erosion may start to damage or loss of the shock absorbing fibrocartilage that covers the bone. “<-We don’t want this however as this would be the foundation of the neo growth plate.

“Normal small joints tend to develop microscopic erosions at sites where the ligament immediately adjacent to the enthesis compresses the bone. This is because the shape of the bone leads to the forces being spread over a wide area that contributes to damage. This occurs at a structure termed a synovio-entheseal complex.”

synovio epiphysis complex

“The black arrows show a microscopic erosion over a knuckle joint. The overlying ligament is shown. The yellow arrow shows the point of ligament attachment closest to the joint cavity. Small blood vessels in the base of the erosion are likely linked to attempted repair. ”

“Sometimes the bone compression by the enthesis organ transmits stresses to the underlying bone and this initially manifests as a small cyst. Later on the roof of this may cave in leading to erosion. ”

bone cyst enthesis

“This is an X-ray (A) and a corresponding tissue section (B). It shows a small bone cyst (BC). This is underneath the cartilage lining the side of the bone. (black arrow). Damage occurs here because the ligament (CL) presses against the bone as it runs between the joints. “<-We’d need more information about the bone cyst to see how promising it is in terms of neo growth plate formation.

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