Narrow Results

Nineteen fresh frozen adult human flexor digitorum profundus (FDP) tendons in Zone II were studied to compare the differences in material properties between the dorsal (dFDP) and palmar (pFDP) side of each tendon biomechanically, biochemically and histologically. We have found that tissue from the dorsal side of each flexor tendon has (1) greater strength; (2) less collagen crosslinking (hydroxypyridinium); and (3) a larger single bundle cross-sectional area than tissue from the palmar side of the same tendon. These data clearly demonstrate that the dorsal and palmar sides of the adult human (FDP) tendon in Zone II differ materially. These differences suggest that there may be biomechanical advantages in placing core sutures dorsally when repairing flexor tendons, a technique that we have previously described.

Background: Dupuytren disease (DD) is characterised by increased myofibroblast/fibroblast activity and type3/type1 collagen ratios. Hyaluronic acid (HA) is major component of the extracellular matrix and some studies have showed that HA limits myofibroblast activity and decreases type3/type1 collagen ratio. The aim of this study is to determine the effect of the ex-vivo application of HA on cultured fibroblasts obtained from normal and diseased tissue from patients with DD. This is the initial step towards defining the use of HA as a new approach for medical treatment of DD.

Methods: Tissue samples were obtained from both healthy forearm (C) and unhealthy palmar (D) fascia of patients undergoing surgery for DD. Tissue samples were cultured and divided into four groups depending on the addition of HA [C(HA−), C(HA+), D(HA−) and D(HA+)]. The tissues were evaluated using Western blot to detect effect of HA on myofibroblast (by measuring alpha smooth muscle actin [α-SMA) and on the ratio of type3/type1 collagen by measuring collagen type1 alpha 1 Chain (COL1A1) and collagen type3 alpha 1 Chain (COL3A1).

Results: The rate of the average α-SMA value in the D(HA+) group was significantly lower compared to that of the D(HA−) group. The average ratio of type3/type1 collagen in the D(HA+) group was significantly lower compared to the D(HA−) group.

Conclusions: The ex-vivo application of HA on cultured fibroblasts obtained from patients with DD resulted in a decrease in myofibroblast/fibroblast activity and type3/type1 collagen ratios. This may pave the way for clinical application of HA in the treatment of DD.

The intervertebral disc is organized with a concentrated proteoglycan solution, the central nucleus pulposus, held within the strong collagen network of the outer annulus fibrosus. The disc exhibits a viscoelastic response when subjected to loads and deformations. Disc degeneration, and/or spondylotic changes that are generally considered to be associated with aging, result in a spinal segment with decreased stiffness. However, in the cervical spine of cerebral palsy patients suffering from athetotic movements of the neck, there is a very early onset of disc degeneration and spondylotic change. Acceleration of disc degeneration has been shown to take place in the spines of animals subjected to excessive extension-flexion of the head and neck. Repetitive torsion of the disc has led to structural regression in in vitro studies using animal spines. Delaminated lamellae and/or disruption of the annulus fibrosus are always recognized in the early stages of the destructive process of the intervertebral disc structure. Disruption of the collagen network may be a result of fatigue failure by repetitive loading, which in turn causes the high tensile stresses in the annulus fibrosus from the development of large hydrostatic pressures within the nucleus pulposus. Loosening of the collagen network may be a key factor leading to the loss of proteoglycans and water, finally inducing the development of disc degeneration. A “degenerated disc” can be induced through pure mechanical fatigue failure of the tissue, as an age-independent degradation of the cartilaginous tissue.

The etiology of most of the degenerative changes in the spine continues to remain obscure. However, several lines of evidence suggest that genetic factors may play an important role in the onset of degenerative changes, in addition to various environmental factors. We have generated transgenic mice expressing mutant αl(IX) collagen in the cartilage matrix. They developed progressive intervertebral disc degeneration with age as well as joint degeneration. Both radiologic and histologic studies indicated that cervical and lumbar disc degeneration was more advanced in the transgenic mice than in control littermates. The initial degenerative changes included shrinkage and replacement of the nucleus pulposus with consolidated fibrous tissue, that resulted in a loss of nuclear-anular demarcation. Partial disruption in the lamellar structure of the anulus fibrosus also occurred at this stage. With age, the disc degeneration progressively advanced and sometimes caused herniation of disc material and mild osteophyte formation. These findings imply that genetic abnormalities of cartilage matrix components, such as type IX collagen, may be responsible for certain degenerative diseases in the spine.