DESIGN RATIONALE
In planning and research prior to design of the ARROW-LOK™ implant, the surgeon design team identified performance objectives for the new implant that would offer clinical advantages over current implant alternatives. These design imperatives included:

Stable fixation

• Keep completely intramedullary with no parts of the implant exposed outside the skin.
• Maintain the initial compression applied at insertion.
• Resist the rotational and pull-out forces affecting the lesser toes.

Simple implant design

• Avoid introducing potential stress-risers and the need to assemble intraoperatively by developing a one-piece design.
• Provide anatomic sizing to fit a broad range of patient anatomy.
• Fit the patient’s natural toe anatomy by providing a neutral and 10° plantar angle.
• Minimize bone removal with a low-profile design.
• Maintain uniform strength characteristics throughout the implant.
• Ensure the product material has a proven long-term biocompatibility so it can be safely implanted permanently. Will not require removal like the K-wire.

Efficient technique

• Create an operative technique similar to that for K-wire fixation with little additional complexity, such as drilling, tapping, or bulky instrumentation.
• Remove little or no bone when preparing the bone for implant insertion while compacting cancellous bone to enhance stable fixation.
• Enable variations in implant placement with respect to the fusion site without any impact on implant effectiveness.
• Allow enough versatility within the interaction between instrument and implant such that the technique may adapt to surgeon preference and patient anatomy.

Proven material

• Must be biocompatible, clinically proven, extensively studied, and commonly used for permanently implanted medical devices.
• Bending and fatigue characteristics able to endure the forces exerted on the lesser toes without having to add unnecessary material volume.
• Capable of being efficiently manufactured to ensure reproducible results.
• Does not require special handling or storage either preoperatively or intraoperatively.

Simple instrumentation

• Instrumentation resembles those with which surgeons are familiar.
• Emphasize simplicity to ensure reproducible results.