Mechanical properties of a rat patellar tendon stress-shielded in situ.
The effects of stress deprivation on the mechanical properties of the patellar tendon (PT) were studied using 14 albino rats. The PT was stress-shielded with cerclages on one side, while the contralateral patellar tendon served as a sham-operated control. After 10 weeks, paired load-strain as well as load-relaxation experiments were performed (11 and 3 specimen pairs, respectively). Mechanical tests showed, irrespective of the cerclage material used, that strain was increased significantly after stress-shielding (P < 0.02). The time constant significantly decreased in the stress-shielded specimens under 5 N loads, which may be considered 'physiological'. Tissue remodeling might explain the observed changes in the viscoelastic behaviour of the stress-shielded tendons. Loading, even in the physiological range of normal daily activity, may lead to an elongation of previously stress-shielded tendons or ligaments and consequently alter the behaviour of a joint.
Müllner
T
T
University Clinic of Traumatology, University of Vienna Medical School, Austria. tmuellner@csi.com
Kwasny
O
O
Reihsner
R
R
Löhnert
V
V
Schabus
R
R
D000818:Animals; D004548:Elasticity; D010329:Patella / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000503:physiopathology*; D013537:Sutures; D013710:Tendons / Q000503:physiopathology*; D013718:Tensile Strength / Q000502:physiology