RESUMO
Objective To investigate the effect of unidirectional stretching on mechanical properties of different absorbable patches and evaluate its potential as a patch for rotator cuff repair. Methods The unidirectional stretching process was used to prepare absorbable patches with different polylactide based materials. Different unidirectional stretching temperatures (50-80 ℃) and stretching ratios (0.5-4.3) were set. The effects of different parameters on mechanical properties of the absorbable patches with different materials were studied. Their thermal properties, crystallization and surface morphology were characterized. Results The unidirectional stretching temperature and stretching ratio could adjust the tensile strength and strain, thermal property, crystalization and surface morphology of the absorbable patch. At directional stretching temperatures of 60, 70, 70 ℃ and stretching ratios of 3, 3, 4.3, respectively, the absorbable patches made of poly-L-lactide-co-glycolide (PLGA), poly-L-co-D, L-lactide (PLDLLA) and poly-L-lactide-co-ε-caprolactone (PLC) had the maximum tensile strength (74±7)，(97±6), (107±8) MPa, which were larger than the tensile strength for infraspinatus tendon of canine (40 MPa). However, only the strain of PLDLLA patch conformed to the flexibility of natural rotator cuff. Conclusions The unidirectional stretching process can improve mechanical properties of the absorbable patch. The absorbable patch made of PLDLLA has the potential to reinforce the rotator cuff tear.