Dynamic Ligament Repair Device With Compression Spring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional static ACL repair devices fail to maintain adequate tension across a range of knee motion, leading to incomplete extension, loosening at higher flexion angles, and inadequate biological healing due to stress being passed through the ligament instead of the suture construct.
Innovation Solution
A dynamic ligament repair device featuring a suture construct with a fixed loop, an adjustable loop, self-cinching sleeves, and a compression spring housed in a threaded screw, which maintains tension across a range of motion by dynamically adjusting to the joint's flexion and extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a static ACL repair device is tensioned in knee flexion, then stability is improved, but the patient cannot fully extend the knee resulting in a locked joint
Solution Approach 1:
The patent applies the dynamics principle by replacing the static suture construct with a dynamic spring-loaded suture device. The spring mechanism allows the suture tension to dynamically adjust as the knee moves through its range of motion, maintaining appropriate tension during flexion while permitting full extension. The spring-loaded anchor system transforms the fixed-length constraint into a variable-length system that adapts to joint kinematics.
2Stability of the object's composition
If a static ACL repair device is tightened in full extension, then stability is improved, but the device loosens at higher flexion angles because the static suture has a fixed length
Solution Approach 1:
The spring-loaded mechanism transforms the static suture system into a dynamic one that automatically maintains tension across the full range of motion. As the knee flexes, the spring compresses to maintain suture tension; as the knee extends, the spring expands while continuing to provide tension. This dynamic adjustment ensures reliable tension maintenance regardless of knee position.
Solution Approach 2:
The patent changes the physical parameter of suture length from fixed to variable by incorporating a spring mechanism. The spring allows the effective suture length to change dynamically with knee motion, maintaining optimal tension parameters throughout the range of motion rather than being constrained by a fixed length set at implantation.
3Device complexity
If a static suture construct is used, then the procedure is simple, but forces are exerted on the repaired ACL tissue causing the suture to rip from the tissue or the tissue to rip away from the bone
Solution Approach 1:
The spring-loaded device distributes forces dynamically during knee motion, preventing concentration of stress at the suture-tissue interface. The spring acts as a shock absorber, reducing peak loads on the repaired ligament and bone-tunnel interfaces during flexion and extension cycles.
4Strength
If conventional ACL repair devices are used, then the initial repair is secure, but they do not promote adequate biological healing because stresses are passed through the ligament instead of being isolated through the suture device
Solution Approach 1:
The spring-loaded suture device acts as an intermediary between the bone tunnels and the repaired ligament. It isolates the ligament from excessive stresses by absorbing and distributing forces through the spring mechanism, creating a protected environment for biological healing while maintaining secure fixation at the bone interfaces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device ensures proper tension on the ligament across a full range of knee motion, isolates stress on the suture construct, and promotes biological healing by absorbing forces of natural knee movement, thereby preventing damage to the repaired ACL.
Implementation Method 1
a compression spring disposed inside the bore, wherein the spring is configured to dynamically maintain tension on the suture construct across a range of motion of the patient's joint
Data Source
AI summary
A dynamic ligament repair device includes a suture, a femoral side suture anchor and a threaded screw or housing implant. The screw is configured for placement in the tibia, or alternatively in the femur. A spring is housed inside an axial bore in the threaded screw. In some embodiments, the spring is a compression spring. A moveable spring button is positioned inside the axial bore adjacent a distal end of the spring. The spring button engages the spring directly in some embodiments. In alternative embodiments, an intermediate structure such as a spacer is positioned between the spring button and the spring. The suture extends between the spring button and the suture anchor. When the joint flexes or extends, the spring button travels inside the axial bore and dynamically compresses or relaxes the spring.