Tendon Retention Device with Anti-Loosening Sleeve
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Solution Overview
Problem
Current surgical procedures for correcting toe contractures, such as hammertoe or claw toe, fail to securely attach the flexor digitorum longus tendon to the plantar base of the proximal phalanx, leading to metatarsophalangeal joint instability and transverse deviation due to inadequate fixation methods, especially in the aging population with osteopenia.
Innovation Solution
A tendon retention device comprising a tack with a threaded shaft and a sleeve with anti-loosening tangs, designed for press-fit or instrument-aided reception into the tendon and bone, providing secure fixation by threading the sleeve onto the tack, ensuring appropriate tendon tension and compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transosseus suturing or small tendon anchor is used to secure the flexor digitorum longus tendon to the plantar base of the proximal phalanx, then the tendon can be attached to the bone, but the fixation is inadequate especially in osteopenic bone leading to joint instability
Solution Approach 1:
The fixation device is divided into two separate components: a tack that is pressed into the tendon and bone, and a sleeve that is threaded onto the tack. This segmentation allows each component to perform its specific function optimally - the tack provides initial anchorage while the sleeve provides threaded retention and tensioning capability.
Solution Approach 2:
The tack is first pressed-fit or instrument-aided into the tendon and bone to establish initial fixation and alignment. This preliminary action creates the foundation for subsequent sleeve installation, allowing the tendon to be positioned correctly before applying final threaded fixation and tensioning.
2Reliability
If the flexor digitorum longus tendon is transferred to the plantar base of the proximal phalanx, then toe alignment is corrected, but inadequate fixation methods cause metatarsophalangeal joint instability
Solution Approach 1:
The fixation system is segmented into a tack component for initial insertion and anchorage, and a sleeve component for threaded retention and tensioning. This segmentation provides reliable joint stability while keeping each individual component relatively simple in design.
Solution Approach 2:
The sleeve acts as an intermediary component that connects the tack (embedded in tendon and bone) to the external environment. It provides the threaded interface for instrument-aided tensioning and secures the tendon fixation while allowing controlled adjustment of tendon tension.
3Ease of manufacture
If transosseus suturing is used to secure the tendon, then the tendon can be attached to the bone, but the procedure is technically difficult and time-consuming
Solution Approach 1:
The tack is pre-formed and ready for immediate press-fit or instrument-aided insertion into the tendon and bone, eliminating the need for complex suturing maneuvers. This preliminary preparation of the fixation device significantly simplifies the surgical procedure and reduces operative time.
Solution Approach 2:
The complex mechanical process of transosseus suturing is replaced by a simpler press-fit or instrument-aided insertion of the tack, followed by threaded engagement of the sleeve. This substitution of the fixation mechanism dramatically reduces surgical complexity and time requirements.
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 enables secure and reproducible fixation of tendons to bones, effectively correcting toe contractures by maintaining tendon tension and stability, thereby alleviating pain and improving surgical outcomes.
Implementation Method 1
The sleeve has an internally threaded bore for threaded reception onto a threaded shaft of the tack
Implementation Method 2
The first component is configured for press-fit or instrument aided reception into the tendon and adjacent bone
Implementation Method 3
The sleeve further has a head with anti-loosening features that are tangs that engage the bone to help prevent the sleeve from working loose and/or unthreading from the bone/tack
Data Source
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AI summary
A device is provided for retaining a tendon, such as, but not limited to, a flexor digitorum tendon onto an associated bone such as, but not limited to, the plantar aspect of a proximal phalangeal base for correction of a toe contracture. The tendon retention device is defined by a tack and a sleeve. The tack is configured for press-fit or instrument aided reception into the tendon and associated bone to retain the tendon against the associated bone. The sleeve has an internally threaded bore for threaded reception onto a threaded shaft of the tack from the opposing side of the associated bone. The sleeve further has a head with an anti-loosening feature or anti-loosening features such as, but not limited to, tangs and/or cutouts, that engage the associated bone to aid in preventing the sleeve from working loose from the bone and/or unthreading from the tack.