Biodegradable implant materials in fracture fixation.
Based on our experiences in paediatric traumatology treated conservatively or with metallic implants, we looked for alternative fixation possibilities in the field of biodegradables.  We designed a new driving system for screws consisting of an indwelling screw driver which transduces the torque force over the whole length of the thread. With this technical approach, the head and the neck of the screw as the most friable point for the fracture of the implant could be avoided. In 48 calves aged 6 weeks we performed a comparative study with either conservative treatment (repositioning and casting) or osteosynthesis with biodegradable screws made from polylactate acid or metallic screws (AO type) after an oblique osteotomy at a 45 degrees  angle to the axis of the right metacarpal bone.  Results from 1 to 6 weeks postoperatively were compared and good to excellent results obtained in equal amounts for PLA and steel screw osteosynthesis, whereas conservative treatment was only successful in one third of the cases.  Clinical, radiological and histological follow-up proved the feasibility of biodegradable osteosynthesis in the growing skeleton.  For clinical evaluation in children, the resorption time of biodegradable materials has to be lowered to 3 to 6 months.
Illi
O E
OE
Department of Surgery, University Children's Hospital, Zürich, Switzerland.
Weigum
H
H
Misteli
F
F
D000818:Animals; D001673:Biodegradation, Environmental; D001863:Bone Screws; D002417:Cattle; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D008663:Metacarpus / Q000601:surgery*; D016348:Osseointegration; D010027:Osteotomy / Q000379:methods; D011091:Polyesters; D013232:Steel; D014945:Wound Healing