The clinical outcomes of scaphoid nonunion treated with a precisely processed autologous bone screw: a case series

Introduction Metal implants and bioabsorbable implants are frequently used in orthopaedic surgery, but they have some disadvantages. The usefulness of autologous bone has been described, and a method to precisely process autologous bone into implants such as screws and apply the implants clinically has been desired. We created a new system for manufacturing autologous bone screws during surgery and report five cases of scaphoid nonunion treated with precise autologous bone screws made from the tibial cortex using the new system. Patients and methods From 2012 through 2017, seven patients were diagnosed with scaphoid nonunion at our hospital and based on the inclusion/exclusion criteria, five of them were analyzed herein. The surgery was performed according to Zaidemberg's technique. The bone screw in each case was made from autologous tibial cortex using a numerically controlled lathe (model MTS4, Nano Co., Yokohama, Japan) under sterile conditions. The change in each patient's modified Mayo wrist score between the preoperative examination and at the final survey was determined, as were complications. Results The median modified Mayo wrist score improved significantly from 65 to 95 points. All patients who were followed for > 2 years fused at a median duration of 3.5 months. Bone regeneration was confirmed at the donor sites in all cases. One fracture at the donor site occurred as a severe complication. Conclusions Precisely shaped autologous bone screws manufactured by a computer-assisted machine, together with a vascularized bone graft, may be a useful technique for treating scaphoid nonunions; these screws had good stability and bone replacement. Careful observation of the donor site is required.