The Degradation Outcome of Biocomposite Suture Anchors Made From Poly L-Lactide-Co-Glycolide and β-Tricalcium Phosphate

Abstract

The purpose of this study was to evaluate the long-term invivo degradation of biocomposite suture anchors made of poly L-lactide-co-glycolide (PLLA/PGA) and β-tricalcium phosphate (β-TCP). Starting in 2008, the invivo biological behavior of a biocomposite suture anchor was studied in a consecutive series of rotator cuff tendon repairs. Twenty patients undergoing rotator cuff repair secured with biocomposite PLLA/PGA-β-TCP suture anchors with at least a 36-month follow-up were evaluated by physical, radiographic, and computed tomographic (CT) evaluations of the operated shoulder. American Shoulder and Elbow Surgeons (ASES), Rowe, Simple Shoulder Test (SST), Constant, and Single Assessment Numeric Evaluation (SANE) scores were also obtained. CT scan data measured in Hounsfield units (HU) evaluated the material density at the anchor sites. Soft tissue and cancellous bone readings were also taken. Osteoconductivity scores were determined at the screw sites using an ossification quality score (range, 1 to 4). Fifteen men and 5 women were evaluated an average of 37 months after surgery (range, 36 to 40). CT scans and radiographs showed no PLLA/PGA-β-TCP anchor material remaining. A total of 28 anchors were implanted in the 20 patients. The anchors were usually replaced with calcified, nontrabecular material. Osteoconductivity was present in 20 of 28 (71%) of the anchor sites and was nearly complete or complete (type 3 or 4 ossification) in 14 of 28 (50%). Mean anchor site density (94 HU) was not different from the mean cancellous bone density (99.8 HU). ASES, Rowe, SST, Constant, and SANE scores improved from 57.3, 64.5, 6.0, 51.7, and 45 preoperatively to 89.6, 86.5, 10.8, 78.6, and 84.3 at follow-up, respectively. All postoperative clinical outcome measures were statistically greater than the preoperative scores. The PLLA/PGA-β-TCP (Healix BR, DePuy Mitek, Raynham, MA) suture anchor completely degraded and no remnant was present 3 years after implantation. Osteoconductivity was confirmed in 20 of 28 (71%) anchor sites and was nearly complete or complete in 14 of 28 (50%). The PLLA/PGA-β-TCP biocomposite suture anchor is osteoconductive. Level IV, therapeutic case series.