The in vivo histology of an absorbable suture anchor: a preliminary report

Suture anchors are playing an increasingly important role in attaching tendons or ligaments to bone. Anchors are usually made of metallic or other nonbioabsorbable materials. The development of an absorbable suture anchor would provide a valuable tool for the surgeon; this characteristic would minimize the problems of anchor loosening, migration, interference with imaging studies, and the potential requirement for later implant removal. This study evaluated the in vivo histological response over time of the first generation Arthrex Expanding Suture Plug (ESP) (Arthrex Inc, Naples, FL). Suture anchors threaded with nonabsorbable No. 2 braided polyester sutures were implanted into ram femurs and removed at various intervals over a period of 12 weeks. After preparation, histological study showed a gradual healing response in the bone tract. There was no evidence of an inflammatory infiltrate or foreign-body reaction during the 12 weeks of implantation. A normal bone callus appeared at the insertion tunnel site consistent with a fracture-healing response. Later, a fibrous membrane appeared at the junction of the implant and the bone tunnel. Over the 12 week interval, there was a decrease in osteoblastic activity and the appearance of cavernous vascular spaces in the superficial portions of the membrane near the periosteum. The ESP anchor composed of poly-L-lactic acid was well tolerated in the in vivo setting. Throughout the study, no substantial acute, chronic, or foreign-body reaction was observed. These observations are consistent with the expected in vivo behavior of poly-L-lactic acid. There is no reason to believe that the ESP composed of poly-L-lactic acid should cause a foreign body reaction.