Five years of experience with biodegradable implants in paediatric surgery

After successful animal research on minipigs and calves, it was decided in January 1988 to begin the clinical application of PLLA (poly-L-lactide) threaded plugs, nuts and woven bands made of PDS (poly-dioxanon). The implants were made of pure crystalline 1-1-PLLA with an average molecular weight between 220 000 and 500 000 I.E. Mechanical testing revealed a Young's modulus of 4000 N mm^-2, a fracture elongation of 2%, and strength values under tension and compression and bending of 55, 110 and 120 N mm^-2, respectively. The PDS bands (Ethicon Corp., type XX40) are commercially available items. Operations were carried out on 32 children, aged 11 months to 17 years, in 15 cases for craniofacial malformations, in 16 patients for neurotraumatological lesions and in 1 girl for refixation of an osteochondral flake of the patella. The follow-up time ranged from 3 months up to 5.6 years, with an average of 3 years. The stability achieved was comparable to that of metal implants. No foreign-body reaction or local infections were observed, and it did not become necessary to remove any of the resorbable implants. Furthermore, there was no interference with skull growth. In accordance with these results, PLLA implants fulfill the needs of skull surgery, and it is intended to increase the application of this type of material to orthopaedic traumatology in children.