Recumbent Stepper Pedal Extension for Post-TKA Knee Flexion
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Solution Overview
Problem
Existing recumbent steppers for TKA rehabilitation lack the ability to provide a repeatable and scalable method for increasing range of motion (ROM) beyond the capabilities of the patient, often requiring external assistance and being hindered by design limitations that interfere with knee movement.
Innovation Solution
An apparatus designed to fit onto the pedal of a recumbent stepper, featuring a higher rail and adjustable straps to secure the foot in place, allowing patients to increase ROM through controlled arm movements, mimicking the heel slide exercise without external assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a standard recumbent stepper pedal is used, then the device is simple and widely available, but the foot position does not allow sufficient knee bend for effective ROM rehabilitation
Solution Approach 1:
The pedal is divided into a standard base portion and an extended extension portion that can be attached separately. This segmentation allows the simple standard pedal to be upgraded with additional functionality without replacing the entire pedal structure, enabling greater knee bend while maintaining compatibility with existing steppers.
Solution Approach 2:
The extension portion adds a new spatial dimension to the pedal by extending backward toward the seat, creating additional foot placement positions. This dimensional extension allows the foot to be positioned farther back, enabling greater knee flexion angles that were not achievable with the standard pedal design.
2Ease of operation
If the seat is moved closer to the pedals to increase knee bend, then ROM improves, but the heel lifts off the pedal losing control and repeatability
Solution Approach 1:
The extension portion provides an additional backward dimension for foot placement, allowing the heel to remain firmly planted on the extended surface even when the seat is positioned close. This extra spatial dimension prevents heel lift-off and maintains reliable foot control throughout the range of motion exercise.
3Ease of operation
If external assistance is used to force the knee beyond patient capability, then ROM increases, but the method is not repeatable or scalable without a therapist
Solution Approach 1:
The extension portion enables the patient's own foot and leg mechanics to automatically provide the necessary leverage for increased knee bend without requiring external manual assistance. The mechanical advantage is built into the pedal structure itself, allowing patients to independently achieve and repeat their maximum range of motion exercises.
4Adaptability or versatility
If the pedal design is modified to accommodate different stepper models, then versatility improves, but manufacturing complexity increases
Solution Approach 1:
The extension portion is designed as a separate attachable component rather than an integrated pedal structure. This segmentation allows the same extension to be used with various standard recumbent stepper models without requiring custom manufacturing for each model, maintaining ease of production while achieving broad versatility.
Solution Approach 2:
The extension portion is designed with universal compatibility features that allow it to attach to multiple different recumbent stepper models. This universal design enables a single extension component to serve multiple functions across different equipment models, achieving versatility without increasing manufacturing complexity.
Data Source
AI summary
A device for increasing the range of motion (ROM) of a patient's afflicted knee joint following total knee arthroplasty (TKA) comprising an apparatus for insertion onto the pedal of an existing recumbent stepper machine. The apparatus enhances the functionality of recumbent steppers by (1) increasing the ROM angle of the knee at every seat position by moving the patient's foot closer to the stepper seat and thus the patient's torso, and by (2) allowing more ankle flection and a deeper guard rail than the original pedal to help maintain heel contact with the apparatus throughout the session.