Transtibial Socket with Patellar Tendon Clearance
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Solution Overview
Problem
Conventional lower limb external prosthetics with patellar-tendon-bars cause discomfort, limit rotational control, and reduce range of motion due to direct support and impingement on the patellar tendon during movement.
Innovation Solution
A socket design with a modified curvature that eliminates or de-emphasizes the patellar bar, focusing on enhanced support of the anterior tibial condyle and tibial tubercle, featuring a lowered edge with indentations on either side to capture the tibia for improved rotational control, and using a flexible containment member in the trough area to reduce pressure on the patellar tendon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a patellar-tendon-bar is provided in the socket to support the patellar tendon, then non-bone contact support is achieved, but discomfort and reduced range of motion occur due to impingement on the tendon during movement
Solution Approach 1:
The patent removes the traditional patellar-tendon-bar structure from the socket design. Instead of providing direct support through a protruding bar, the invention extracts this element and replaces it with a contouring approach that follows the natural anatomy of the residual limb, allowing the patellar tendon to move freely without impingement while still providing necessary support through the overall socket geometry.
Solution Approach 2:
The socket is designed with differentiated local contours that specifically accommodate the patellar tendon region. The interior surface features a smoothly contoured area that follows the anatomy of the residual limb, providing localized support where needed while maintaining clearance in the patellar tendon area to prevent impingement during flexion and extension movements.
2Strength
If a conventional patellar bar is located several inches down from the top edge of the socket, then structural support is provided, but rotational control is reduced
Solution Approach 1:
The invention transitions from a single-point bar support located distally to a distributed contouring approach that engages multiple dimensions of the residual limb interface. By creating a three-dimensionally contoured interior surface that wraps around the anatomy, the design achieves rotational control through distributed contact areas rather than relying on a single distal bar location.
3Ease of operation
If the socket top edge is positioned to contact the patellar tendon region, then containment is improved, but range of motion is limited due to direct support and impingement
Solution Approach 1:
The socket interior surface is designed with dynamic clearance that adapts to the movement of the residual limb. The contouring creates variable spacing between the socket wall and the patellar tendon region, allowing greater freedom of movement when the tendon needs to move during gait cycles while maintaining adequate containment through the overall socket geometry and distal locking mechanisms.
Data Source
AI summary
A prosthetic hard socket has a modified curvature and/or shape, which eliminates or de-emphasizes the patellar bar to eliminate or reduce pressure on the wearer's patellar tendon, and, instead, enhances support of the anterior tibial condyle and/or tibial tubercle. Thus, the preferred socket is designed with the patellar tendon preferably not being weight-bearing. The preferred curvature and/or shape comprises a lowered socket edge and/or a gap in the socket wall in the region of the patellar tendon, so that the hard structure of the socket does not directly support or press upon the patellar tendon. The invented socket may include inwardly-protruding regions on each side of the lowered edge/gap, for helping to “capture” or otherwise press on a portion of the tibia for improved rotational control. This combination of shapes and curvatures provides for improved rotational control, comfort, and range of motion including even full extension or hyperextension. A flexible and/or cushioning member may be placed in the gap/trough (that is caused by the lowered edge or removed wall portion), for example, a fabric, leather, rubber, or other member may be attached to the socket to across a V-shaped trough of the lowered edge of the hard socket.