Monkey Rings External Ring Fixation System

The Monkey Rings External Ring Fixation System is a modular, ring-based external fixation device for treating fractures, deformities, and limb lengthening in pediatric and adult patients. It consists of circular rings connected by adjustable struts, pins, wires, and other components that can be configured to stabilize bone segments during fracture management, deformity correction, or limb lengthening procedures.

The subject device adds a universal joint strut component that enables off-axis circular ring fixation and allows controlled lengthening/shortening with lockout mechanisms. Both subject and predicate devices use stainless steel or titanium pins and tensioned wires, manual adjustable struts with lockout mechanisms, and optional hinges for controlled joint movement. The key difference is the universal joint strut versus the predicate's ball joint struts, which the manufacturer characterizes as a minor design change that maintains overall frame stability.

ASTM F1541-17 was used for performance testing, including Static Axial Grip of Connector, Static Torsional Grip of Connectors and Fixators, Static Compression of Rings, Dynamic Axial Compression of Construct, Evaluation of Bending and Torsional Strength of Pins, and Evaluation of Static Compression of Subassembly. A sterilization assessment (TR-23080701) was also performed to confirm sterility assurance and material, mechanical, and functional integrity.

The Monkey Rings system has the same intended use and substantially similar technological characteristics as the predicate Paragon 28 External Ring Fixation System (K212895). The addition of the universal joint strut is a minor design modification that does not affect intended use, performance, or safety profile, and therefore does not raise different questions of safety or effectiveness.