Development of small diameter intramedullary nails made from ISO 5832-9 stainless steel

Abstract

<jats:p> <jats:bold>Background</jats:bold>: In order to improve strength in small diameter intramedullary nails, a system was designed in which the implants were manufactured from 30% coldworked ISO 5832–9 stainless steel.</jats:p><jats:p> <jats:bold>Methods</jats:bold>: Nail diameters were 9 and 10 mm for the femur, and 8 and 9 mm for the tibia. The nails were solid rods and the screws were partially threaded. Pre‐clinical bending yield tests established that the 8‐, 9‐ and 10‐mm diameter rods had strengths comparable, respectively, with 10‐, 12‐ and 14‐mm diameter Grosse–Kempf nails. Forty‐eight femoral and 98 tibial shaft acute fractures were treated with this system. Postoperatively, patients were allowed to gently bear weight as tolerated.</jats:p><jats:p> <jats:bold>Results</jats:bold>: There was one broken nail, occurring 10 months after femoral nailing. There were six broken screws, occurring between 3 and 6 months postoperatively in two patients and after more than 6 months in four patients. The broken screws had no adverse clinical effect. Five patients required late bone grafting or exchange nailing, and 15 patients required dynamization.</jats:p><jats:p> <jats:bold>Conclusion</jats:bold>: This design of small diameter locked intramedullary nails was strong enough to allow early weightbearing.</jats:p>