Experimental study on thermal welding for the knee meniscal white zone

Abstract

It is difficult to repair tears of the meniscus at the white zone by suturing. We considered that there might be an optimal tissue welding temperature when thermally welding the meniscal white zone, so we conducted a thermal welding experiment using bovine and human menisci. The samples prepared after thermal welding were investigated by measuring the tensile strength, analyzing the histological findings of the welded portion and the meniscal parenchyma, and conducting biochemical analyses. In the experiment using human menisci, histological findings were investigated using transmission electron microscopy (TEM). As the findings on the welded tissue in the white zone of the bovine meniscus indicated positive results at 63°C and 69°C, the experiments using human meniscal white zone were conducted at these two temperatures. The highest tensile strength after thermal welding of the human meniscal white zone was 101.4 ± 2.6 g/cm2 at 63°C. Although there were no significant differences in the amount of pyridinoline per unit collagen weight [Pyr/Hpr (%)] in the human meniscus after thermal welding between the control group and various temperature groups (55°C, 63°C, 69°C, 75°C), the amount of pyridinoline per unit of collagen weight tended to decline as the welding temperature increased. According to the TEM findings, the internal structure of the nuclei of the cells was preserved in the 63°C group, whereas cells were denatured inside the nuclei in the 69°C group. They exhibited necrosis, making cell regeneration difficult. Therefore, it seems feasible that thermal welding at 63°C can repair tears in the human meniscal white zone.