Growing Spinal Rod Ratchet Mechanism
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Solution Overview
Problem
Current growing spinal rod systems require frequent surgical interventions to adjust their length, which is undesirable for maintaining spinal correction and allowing skeletal growth in younger patients with scoliosis, as it interferes with normal growth and height maintenance.
Innovation Solution
A growing spinal rod system comprising a housing with a stepped passage and spacers that allow a spinal rod to extend and lock in place, enabling length adjustment without surgical intervention, using a combination of ribs, mating protrusions, and set screws for secure fixation and visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional growing spinal rod systems are used, then spinal correction and stability are provided, but repeated surgical interventions are required every six months to adjust length
Solution Approach 1:
The spinal rod system enables self-adjustment through a ratchet mechanism that allows the rod to lengthen automatically in response to spinal growth forces. The rod can be extended by threading it through the housing and spacers, while the ratchet mechanism prevents shortening, eliminating the need for repeated surgical interventions to adjust length.
2Length of moving object
If manual length adjustment through surgical procedure is performed, then spinal rod length can be increased, but patient undergoes repeated surgeries which interferes with normal growth
Solution Approach 1:
The system transitions from a static, fixed-length rod to a dynamic, adjustable-length rod that can respond to growth forces. The ratchet mechanism allows unidirectional adjustment (lengthening only), enabling the spinal rod to adapt to the patient's growing spine without requiring repeated surgical procedures that would interrupt normal development.
3Adaptability or versatility
If the spinal rod is made extendable without surgical intervention, then growth accommodation is improved, but device complexity increases
Solution Approach 1:
The spinal rod system is divided into modular components: a housing containing the ratchet mechanism, spacers with through-holes for rod passage, and an extendable rod itself. This segmentation allows the complex function of adjustable length to be achieved through simple, discrete parts that work together, making the system both adaptable to growth and manufacturable.
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 system allows for non-invasive length adjustment and growth accommodation, reducing the need for repeated surgeries by permitting the spinal rod to extend naturally with patient growth while maintaining spinal correction, thus supporting skeletal development without repeated surgical procedures.
Implementation Method 1
The first spinal rod urges the plurality of ribs outwards when the first spinal rod is inserted through the through hole of the at least one spacer. The ribs permit the first spinal rod to extend from the housing through the first end of the stepped passage and inhibit the first spinal rod from retracting into the housing
Data Source
AI summary
A growing spinal rod system is configured to grow in response to the growth of a patient. The growing spinal rod system includes a housing, a spacer, and a sliding spinal rod. The housing includes a stepped passage therethrough. The spacer is disposed within the stepped passage and defines a through hole. The spacer includes a plurality of ribs biased inwards and into the through hole. The sliding spinal rod is slidably inserted through the through hole of the spacer. The sliding spinal rod moves the plurality of ribs outwards. The plurality of ribs permits the sliding spinal rod to extend from the housing and inhibit the sliding spinal rod from retracting into the housing.