Tissue response after implantation of pure titanium and bioresorbable screws in scapula with postoperative irradiation: an experimental study on rats

Objective The study focuses on the comparison of tissue reaction to titanium and bioresorbable implants with and without postoperative irradiation on an animal model. Materials and Methods Thirty-nine LEW/W rats were randomly assigned to experimental or control groups. One titanium and one bioresorbable screw (poly–L–lactide [PLLA] and L– and D–lactide poly–L/D–lactide [PDLLA]) were implanted into the left scapulas of 24 rats. Half of them received 30 Gy to the operation site and the other half received 42 Gy. In the control groups, 3 rats received 30 Gy, and 6 rats received 42 Gy to the scapula area without operation; and 6 rats had implants inserted as in the experimental group, but received no postoperative irradiation. The scapulas were removed 14 or 30 days after irradiation and a histologic analysis was performed. Results The host tissue reaction to titanium and PLLA–PDLLA screws without postoperative irradiation was of similar intensity. In irradiated animals, the inflammatory tissue reaction was more evident around the titanium screws than around the bioresorbable screws, irrespective of the radiation dose and of the time that elapsed from the irradiation. The reaction was more evident on the 14th day than on the 30th day after the last radiation dose (70 and 86 days after surgery, respectively). The intensity of the inflammatory tissue reaction, irrespective of the implant type, was more intense in the group irradiated with 42 Gy. Conclusions PLLA–PDLLA implants appear to cause less tissue reaction after irradiation and could be safer reconstructive devices than titanium implants for patients undergoing surgery and adjuvant radiotherapy for cancer.