A resorbable rivet system for pediatric craniofacial surgery: biomechanical testing and clinical experience

The use of a new method of bone fixation for pediatric craniofacial surgery was evaluated by both biomechanical tests and clinical use. A "pull-back" rivet composed of 82% poly-L-lactic acid and 18% polyglycolic acid (LactoSorb) for use with resorbable plates was developed to obviate the traditional hand-tapping technique used for the placement of resorbable screws. In in vitro testing, the average failure load of the rivets in uniaxial pullout was nearly 50 kg and approximately 75 kg in shear. Approximately two thirds of their initial strength was retained by 6 weeks. In clinical testing, 10 patients undergoing cranial vault reconstruction were treated by 1.5-mm resorbable plates secured by rivets. Although postoperative clinical outcomes were unaffected, good engagement of the devices with secure plate fixation was obtained in only about 70% of the rivets fired. Although the novel approach of a pull-back rivet was encouraging in both design and in vitro testing, its clinical use is impaired by the sensitivity of the device to the thickness of the bone into which it is placed, as well as its larger diameter compared with resorbable screws.