Fixation of Osteochondritis Dissecans Lesions Using Poly(l-lactic Acid)/ Poly(glycolic Acid) Copolymer Bioabsorbable Screws

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Abstract
Background: Many osteochondritis dissecans lesion fixation techniques are effective. A new absorbable copolymer screw maybe suitable for this application. Purpose: To characterize the mechanical and in vitro absorption properties of a copolymer fixation screw and determine theclinical efficacy of using the screw to fix osteochondritis dissecans lesions. Study Design: Case series and laboratory study; Level of evidence, 4. Methods: Seven patients diagnosed with unstable, partially open osteochondritis dissecans lesions were treated withdebridement of the bed and fixation with 2.5-mm diameter screws made of Lacto Sorb copolymer; the patients were nonweightbearingfor 6 weeks. Clinical and radiographic follow-up was for 25 to 37 months. Biomechanical testing was performed in syntheticbone over a 12-week period on buffer-incubated specimens. Results: Six of the 7 osteochondritis dissecans lesions healed clinically and radiographically; the osteochondritis dissecansfragment was removed from the seventh patient (unhealed). No symptoms indicative of an inflammatory reaction related to thepresence of the absorbable screws, including recurrent effusion, warmth, or erythema, were noted. In the in vitro testing, theinitial average peak pull-out and shear loads were 20.1 kg and 22.3 kg, respectively, with little strength remaining at 12 weeks. Conclusions: In general, the 2.5-mm-diameter Lacto Sorb copolymer screws provided adequate stability for healing ofosteochondritis dissecans lesions and degraded without an inflammatory response by the body.