With michael benjamin he also recognised the importance structures that whilst not inserted to the bone behave functionally as enthesis including fibrocartilaginous synovial joints and wrap around tendons these structures have collectively been called functional enthesis. Articular enthesis organs were found at 14 entheses, including the attachments of the digital extensor tendons and collateral ligaments, the cruciate ligaments, tibialis anterior, the lateral collateral ligament of the knee, and the popliteal tendon.
A identity of fibrocartilage benjamin and evans, 1990 carvalho and felisbino, 1999 stockwell, 1979 benjamin and ralphs, 1998 ) the absence of either molecule from the body as a whole can have severe effects on skeletogenesis ( . The ‘enthesis organ’ some tendon attachments are associated with an adjacent fat pad, sesamoid, fibrocartilage and/or bursa the most well-studied of such sites is the insertion of the achilles tendon 21.
Understanding the enthesis organ concept helps to explain synovitis and osteitis in spondy-loarthropathy an appreciation of the complex anatomy of ‘articular enthesis organs’ (eg, that associated with the distal interphalangeal joints) is helpful in understanding disease patterns in psoriatic arthritis. This is important for understanding the nature and scope of pain and inflammation associated with enthesis disorders with michael benjamin he also recognised the importance structures that whilst not inserted to the bone behave functionally as enthesis including fibrocartilaginous synovial joints and wrap around tendons these structures have collectively been called functional enthesis. The enthesis organ the enthesis organ is composed of the enthesis insertion and adjacent tissues whilst the insertion provides firm anchorage to the underlying bone the enthesis organ comprises several other tissues the actual point of insertion is shown by the arrowheads in the figure below.
The articular enthesis organ of the popliteal tendon (pt) and the lateral collateral ligament (lcl) a, note the complete continuity of the tendon and ligament entheses (arrows) f = femur bar = 2 mm b, an integral part of the enthesis organ is the popliteal groove of the femur, which is covered with articular cartilage (ac. Benjamin m, mcgonagle d (2009) the enthesis organ concept and its relevance to the spondyloarthropathies in: lópez-larrea c, díaz-peña r (eds) molecular mechanisms of spondyloarthropathies advances in experimental medicine and biology, vol 649.
This contact between tendon/ligament and bone influences stress dissipation at the enthesis itself, and has led benjamin & mcgonagle (2001) to propose the concept of an ‘enthesis organ’ they define an ‘enthesis organ’ as a collection of related tissues at and near the enthesis, which serve a common function of stress dissipation. Entheses are regions where a tendon, ligament, or joint capsule attaches to bone (benjamin & mcgonagle 2001) disorders of entheses (eg enthesopathies) are commonly found in seronegative (rheumatoid factor negative) spondyloarthropathies, including as.
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. Entheses organ an entheses organ is an interface where a subtendinous bursa is present for friction reduction as the insertion angle of the collagen fibers changes during joint movement this allows direct tendon-bone contact dissipating the stress away from entheses which is similar to mechanics involved in fibrous attachments 161.
Understanding the enthesis organ concept helps to explain synovitis and osteitis in spondy loarthropathy an appreciation of the complex anatomy of 'articular enthesis organs' (eg, that associated with the distal interphalangeal joints) is helpful in understanding disease patterns in psoriatic arthritis.