The mechanical properties of tail tendon fascicles from lubricin knockout, wild type and heterozygous mice.

The purpose of this study was to analyze the effects of lubricin on tendon stiffness and viscoelasticity. A total of 36 mice were tested with 12 mice in each of the following groups: lubricin knock-out ⁻/⁻, heterozygous ⁺/⁻ and wild-type ⁺/⁺. A ramp test was used to determine the elastic modulus by pulling the fascicles to 2.5% strain amplitude at a rate of 0.05 mm/s. Then, followed by a relaxation test that pulled the fascicles to 5% strain amplitude at a rate of 2 mm/s. The fascicles were allowed to relax for 2 min at the maximum strain and a single-cycle relaxation ratio was used to characterize viscoelastic properties. There was no significant difference in the Young's modulus between the three groups (p > 0.05), but the knockout mice had a significantly (p < 0.05) lower relaxation ratio than the wild type mice. Based on these data, we concluded that lubricin expression has an effect on the viscoelastic properties of tendon fascicles. The clinical significance of this finding, if any, remains to be demonstrated.

[1]  S. Schwartz,et al.  CACP, encoding a secreted proteoglycan, is mutated in camptodactyly-arthropathy-coxa vara-pericarditis syndrome , 1999, Nature Genetics.

[2]  Renato V. Iozzo,et al.  Targeted Disruption of Decorin Leads to Abnormal Collagen Fibril Morphology and Skin Fragility , 1997, Journal of Cell Biology.

[3]  Louis J. Soslowsky,et al.  Effect of Altered Matrix Proteins on Quasilinear Viscoelastic Properties in Transgenic Mouse Tail Tendons , 2003, Annals of Biomedical Engineering.

[4]  R. Vanderby,et al.  The effect of in situ freezing on rabbit patellar tendon , 1992, The American journal of sports medicine.

[5]  Kai-Nan An,et al.  Tendon fascicle gliding in wild type, heterozygous, and lubricin knockout mice , 2011, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[6]  K Hayashi,et al.  Mechanical properties of collagen fascicles from stress-shielded patellar tendons in the rabbit. , 1999, Clinical biomechanics.

[7]  K. An,et al.  Expression and mapping of lubricin in canine flexor tendon , 2006, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[8]  K. An,et al.  Lubricin surface modification improves tendon gliding after tendon repair in a canine model in vitro , 2009, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[9]  H. Screen.  Investigating load relaxation mechanics in tendon. , 2008, Journal of the mechanical behavior of biomedical materials.

[10]  B. Bach,et al.  A Biomechanical Analysis of Bone-Patellar Tendon-Bone Grafts After Repeat Freeze-Thaw Cycles in a Cyclic Loading Model , 2009, The journal of knee surgery.

[11]  R. F. Ker.  Mechanics of tendon, from an engineering perspective , 2007 .

[12]  L. Soslowsky,et al.  Influence of decorin and biglycan on mechanical properties of multiple tendons in knockout mice. , 2005, Journal of biomechanical engineering.

[13]  B. Caterson,et al.  Immunolocalisation and expression of proteoglycan 4 (cartilage superficial zone proteoglycan) in tendon. , 2002, Matrix biology : journal of the International Society for Matrix Biology.

[14]  K. Baar,et al.  Tendon mechanics: the argument heats up. , 2007, Journal of applied physiology.

[15]  P. Scott,et al.  Increased diameters of collagen fibrils precipitated in vitro in the presence of decorin from various connective tissues. , 1997, Connective tissue research.

[16]  F H Silver,et al.  Self-assembly of collagen fibers. Influence of fibrillar alignment and decorin on mechanical properties. , 1997, Biophysical journal.

[17]  K. An,et al.  The effect of hyaluronidase, phospholipase, lipid solvent and trypsin on the lubrication of canine flexor digitorum profundus tendon , 2008, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[18]  K. An,et al.  Age-dependent changes in the mechanical properties of tail tendons in TGF-β inducible early gene-1 knockout mice , 2006 .

[19]  P. Boesecke,et al.  In situ multi-level analysis of viscoelastic deformation mechanisms in tendon collagen. , 2010, Journal of structural biology.

[20]  M. Kjaer,et al.  Lateral force transmission between human tendon fascicles. , 2008, Matrix biology : journal of the International Society for Matrix Biology.

[21]  D. Elliott,et al.  A biphasic and transversely isotropic mechanical model for tendon: application to mouse tail fascicles in uniaxial tension. , 2004, Journal of biomechanics.

[22]  K. An,et al.  Lubricin surface modification improves extrasynovial tendon gliding in a canine model in vitro. , 2008, The Journal of bone and joint surgery. American volume.

[23]  Véronique Lefebvre,et al.  The secreted glycoprotein lubricin protects cartilage surfaces and inhibits synovial cell overgrowth. , 2005, The Journal of clinical investigation.