title: Degradation of poly-L/DL-lactide versus TCP composite pins: a three-year animal study.
abstract: Biodegradable polylactide implants allow secure fixation of osteochondral fractures. This quasirandomized parallel-group animal study investigates whether a composite implant of poly-L/DL-lactide (PLDLLA) with additional 10% beta-tricalcium phosphate produces an osteoconductive effect, whether the admixture positively influences implant degradation (assessed by comparing time to implant degradation), and whether the pin sites of degraded implants are replaced with bone tissue. On 36 medial femoral condyles of sheep, osteotomies were fixed with either three PLDLLA pins or three composite pins. At 3, 18, and 36 months, the pin sites were measured histologically and the state of degradation assessed according to Pistner's classification. All fractures healed without clinically relevant complications and without displacement. Both pin types led to asymptomatic pin-site enlargement at 18 months, which disappeared by 36 months. At 18 months, 14 of 18 PLDLLA pins were no longer evident, whereas 16 of 18 composite pins showed only peripheral degradation. By 36 months, all implants from both groups were completely degraded and replaced with scar (2/18) or bone tissue (16/18). At 36 months there was no evidence for significant improvement of either degradation performance or osseointegration through use of the 10% TCP composite mixture.
authors.affiliation: Department of Trauma and Reconstructive Surgery, University of Cologne, Joseph-Stelzmann-Strasse 9, D-50924, Cologne, Germany. axel.prokop@uk-koeln.de
authors.forename: Axel
authors.initials: A
authors.lastname: Prokop
authors.forename: Andreas
authors.initials: A
authors.lastname: Höfl
authors.forename: Martin
authors.initials: M
authors.lastname: Hellmich
authors.forename: Axel
authors.initials: A
authors.lastname: Jubel
authors.forename: Jonas
authors.initials: J
authors.lastname: Andermahr
authors.forename: Klaus
authors.initials: K
authors.lastname: Emil Rehm
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hahn
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000378:metabolism*; D002130:Calcium Phosphates / Q000378:metabolism*; D007719:Knee Joint / Q000378:metabolism* / Q000601:surgery; D007720:Knee Prosthesis; D023421:Models, Animal; D011091:Polyesters / Q000378:metabolism*; D012756:Sheep; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D011091:Polyesters; C033616:poly(lactide); C018392:tricalcium phosphate