The Shear Strength of the VLPTM Locking Osteopenia Screw versus the VLP Locking Cortical Screw in a PERI-LOCTM VLP One-Third Locking Tubular Plate Construct

Deformity correction and internal fixation during surgical treatment of Charcot Arthropathy (CA) requires strong implants capable of ensuring long-term stability and function of the foot. The purpose of this study was to determine the construct shear strength of the newly developed VLP Locking Osteopenia Screw (Smith & Nephew, Inc., Memphis, TN, USA), as compared to the VLP Locking Cortical Screw (Smith & Nephew, Inc.) in a PERI-LOC VLP One-Third Locking Tubular Plate (Smith & Nephew, Inc.). A foam bone analog was cut and placed into a testing device to simulate supported and unsupported fracture conditions. The construct was loaded perpendicular to the plate to reproduce the plantar loading patterns of a typical neuropathic CA patient. The simulated fracture was reduced with a PERI-LOC VLP plate and either the osteopenia or cortical locking screws and then loaded until failure. Testing results demonstrated that construct shear strength was approximately 1.7 times higher for the osteopenia screw construct (p<0.05). This evidence suggests that performance of the VLP Locking Osteopenia Screw can be expected to exceed that of the VLP Locking Cortical Screw under similar loading conditions.