Abstract
Background
Hyperlaxity is associated with a high incidence of sporting injuries. Collagen V regulates the diameter of fibrils of the abundant collagen type I. Decorin and biglycan are members of the small leucine rich proteoglycans(SLRP's)family and play important roles in the regulation of collagen fibrillogenesis. The aim of this study was to identify if there was a link in hyperlaxity, tissue strength, collagen V and SLRP's expression.
Patients and methods
Data was collected for 25 patients. 12 had open shoulder stabilization and 13 had primary ACL reconstruction. Beighton score was used to assess hyperlaxity. Localization of Collagen V and SLRP's was studied by immunohistochemical staining of the paraffin embedded sections of the skin. Grading of the stain was done on a 0-4 scale(0=no staining and 4=strong staining>50% of the slide)by three observers. Tissue specimens were mounted on a material testing system and vertical load was applied to reach yield.
Results
The mean force required for yield in 43 tissue specimens was 70N(12-171). Data was analysed for Group A(weak group)with yield<70N(21 tissue specimens)and Group B(strong group)with yield>70N(22 specimens). The mean age was 27 years. The mean force for group A was 41N(12-67)and group B was 98N(70-171). The mean Beighton score for group A was 3.4(0-9)and Group B was 1.9(0-5). 9 specimens in Group A and 4 in Group B had Beighton score>4 indicating hyperlaxity. The mean grading of collagen V expression in skin dermal papilla was 2.4, appendages 2.2 and extracellular matrix(ECM)1.8 in group A and 1.3,1.8 and 1.7 respectively in Group B. The mean grading of decorin expression in skin was 3.2 in group A and 3.1 in Group B. The mean grading of biglycan expression in skin epidermis was 1.5, appendages 2.2, ECM in superficial dermis 1.5 and deep dermis 0.75 in group A and 1.75,2.1,1.5 and 0.5 respectively in Group B.
Conclusion
We found that weaker tissue specimen had high incidence of hyperlaxity and increased grading of expression for Collagen V in the skin dermal papillae. No difference was found in SLRP's expression in skin in both groups. The study shows a link between hyperlaxity, tissue strength and Collagen V expression in skin dermal papillae.
