Die Zusammensetzung der extrazellulären Matrix der Sehnen- und Bandansätze am Os pisiforme

According to recently published studies two types of entheses are
discussed, a fibrous and a fibrocartilaginous one. The fibrous
enthesis is seen transmitting only tensile forces of muscle to the
bone, while the fibrocartilaginous enthesis in addition is also
seen dissipating stress away from the hard- soft- tissue-
interface. The pisiforme bone in its role as a bony pulley
(Hypomochlion) splits the force of the m. flexor carpi ulnaris on
two ligaments. One of those is running in line of the tendon from
the m. flexor carpi ulnaris, while the other branch is running in
an angle of 45° according to them. The aim of the present study is
to describe the molecular composition of the insertions from the
pisiforme bone, expecting both types of entheses. Eleven pisiform
bones are taken from bodies at the latest 48h post mortem. They
were fixed in methanol, decalcified and cryosectioned. Sections
were labelled with monoclonal antibodies directed against
collagens, glycosaminoglycans proteoglycans and other specific
matrixproteins. All attachment sites showed fibrocartilaginous
entheses. Typically these zones of fibrocartilage are labelling
strongly for type II collagen, aggrecan and link- protein. The
ligaments themselves are labelling for collagen type I and III,
chondroitin 4 sulfate, keratan and dermatan sulfate, versican and
tenascin. The area of the fibrocartilaginuos region is varying
between the entheses, which is interpreted as functional adaptation
to the prevailing forces.