A Biomechanical Study Comparing Patient-Specific Plates with Standard Plates for Distal Radius Malunion Correction

Background: Malunions of the distal radius are the commonest complication of distal radius fractures and can be debilitating. A corrective osteotomy seeks to restore the patient's anatomy, with advances in technology permitting the use of patient-specific technology to accurately achieve this goal. This study compares the biomechanical properties of these systems, against standard implants, with the hypothesis that improved biomechanical properties may translate into improved functional and clinical outcomes for these patients. Methods: Ten artificial, identical, 3D-printed right distal radii were randomised. Five samples were fixed using a standard distal radial locking plate, with a pre-determined osteotomy site using planning software (control group). The remaining five samples were prepared using a 3D-printed jig, prior to fixation with a patient-specific distal radius locking plate (intervention group). A further five general distal radius sawbones were prepared and fixed using standard techniques, using the same pre-determined osteotomy level and degree of correction as the other groups (baseline group). The specimens were cyclically loaded for 2,000 cycles. Primary outcome was interfragmentary motion at the osteotomy site, with secondary outcome measures of stiffness of the construct and failure. Results: We found a statistically significant difference in motion when comparing the intervention and control groups, at both 80 N and 250 N of load (80 N: 88 µm, p < 0.001; 250 N: 316 µm, p < 0.001). The difference between the control and baseline groups was not found to be statistically significant (80 N: p = 0.13; 250 N: p = 0.088). The patient-specific implant was found to be the stiffest construct of the three specimens, and this difference was statistically significant. Conclusions: Our study shows increased mechanical stability in patient-specific implants, which may support earlier rehabilitation of patients. However, this study has highlighted a need for high-quality clinical research, to investigate how this data translates into the clinical, functional and union outcomes for these patients.