comparison of biocompatibility and biomechanical characteristics between titanium and stainless steel suture anchors: an in vitro study of toxicity and tensile strength

Screw anchors are used in shoulder joint surgery, particularly in rotator cuff repair. indonesia has locally-produced titanium (tiosh tisa) and stainless steel (tiosh sssa) anchors, which are more affordable than imported options. however, there have been no studies examining the biocompatibility and biomechanics of these anchors. this study aimed to analyze the differences in toxicity and tensile strength between domestically produced tiosh tisa and sssa. this in vitro study was conducted in march–december 2024. toxicity was assessed using the elisa method with 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (mtt) assay. toxicity is defined as the death of >25% of cells in the test material. biomechanical testing was conducted with a universal testing machine (model ht-2402; hung ta, taiwan) using anchors fixed to the human femoral head. the data were analyzed using spss software. toxicity tests were performed with 10 replications in each group. the average percentage of live cells of tiosh tisa and tiosh sssa were 166.52±35.04% and 171.91±23.98% (p=0.693). we conducted biomechanical tests with 8 replications per group. compared to tiosh sssa, tiosh tisa exhibited a greater maximum force (mean difference 124.68; 95% confidence interval [ci]: 58.46-190.89 n, p=0.001), greater tensile strength (mean difference 9.92; 95%ci: 4.65-15.19 n/mm2, p=0.001), greater young’s modulus (mean difference 93.62; 95%ci:16.01-171.23 n/mm2, p=0.022), and smaller elongation (p<0.001). there were no differences in yield strength between both groups (p=0.142). both screw anchors are non-toxic. compared with tiosh sssa, tiosh tisa produced higher maximum force, tensile strength, and young’s modulus, along with lower elongation.