Fig 1.
The humerus was placed in a custom made fixture and the tendon attached to a cryo-clamp for testing.
Failure was tested at 1 mm/s and the direction of pull of the tendon was directly superior and along the axes of the ISP tendon fibers.
Table 1.
Summary of morphological data and experimental outcomes.
Fig 2.
Significant differences were observed in bone mineral density of the humeral head between the Control, OVX-Saline and OVX-PTH groups.
Bone mineral density in the OVX-PTH group was significantly higher than in the OVX-Saline group but similar to that of the Control group.
Fig 3.
Failure stress for all groups.
Although not significant, a visual trend can be observed where the OVX-Saline group presents smaller failure loads when compared to the Control and OVX-PTH specimens. This shows the effect of PTH administration in increasing failure strength and potentially preventing rotator cuff tears.
Fig 4.
A positive linear correlation was observed between failure stress and bone mineral density measured at the humeral head.
Fig 5.
4-layered tendon-bone interface of ISP enthesis: tendon, nonmineralized fibrocartilage (*), mineralized fibrocartilage (▲) (▲), and bone. (↑) indicates the tidemark.
In the Control and OVX-PTH groups, well-organized ISP enthesis could be observed with a clear tidemark (A, D). Arrangement of nonmineralized fibrocartilage aligned well, nonmineralized and mineralized fibrocartilage were stained deeply and with abundant cells (B, E). In the OVX-PTH group, the nonmineralized and mineralized fibrocartilage were thicker with a more compact structure (E, F). In OVX-Saline group, a relative thinner tendon-bone interface was observed, as well as a less clear tidemark in the enthesis (G). The cell deposition in the area was less compared to the other groups, and osteoclast number and bone lacuna in the mineralized fibrocartilage seemed to have increased compared to both Control and OVX-PTH groups (H, I).