Hip Screw Assembly with Selectable Compression Stops

The patent applies preliminary anti-action by providing stops positioned within the barrel that preemptively prevent the lag screw from moving beyond safe limits. The first stop prevents lateral backout by limiting how far the screw can move away from the femoral head, while the second stop prevents medial cutout by limiting how far the screw can advance into the femur. These stops are installed before surgery to pre-establish boundaries that prevent harmful movements while allowing necessary compression.

The patent implements preliminary action by pre-configuring the barrel with adjustable stops that can be set to specific positions before the surgical procedure. The stops are positioned at predetermined distances from the lateral end of the barrel, allowing the surgeon to select appropriate compression limits in advance. This preliminary configuration ensures that the screw movement is controlled within safe parameters while enabling the desired compression effect.

The patent applies dynamics by making the anti-rotation feature adjustable rather than fixed. The key can be positioned at different locations along the lag screw, and the keyed configuration can be selected based on the specific surgical requirements. This dynamic adaptability allows the same barrel and screw components to provide rotation control when needed while maintaining the ability to allow rotation when appropriate, eliminating the need for multiple specialized inventory items.

The patent implements universality by designing a single barrel and lag screw system that can perform multiple functions depending on configuration. The same components can be used with or without the keying feature engaged, allowing the device to provide either rotation control or free rotation as clinically indicated. This multi-functionality reduces inventory requirements while maintaining the ability to address different fracture types and surgeon preferences.