# Non-invasively extendable megaprosthesis

> **NIH NIH R44** · GRANITE MEDICAL, LLC · 2024 · $685,746

## Abstract

ABSTRACT
This project is the development of a non-invasively extending distal femur replacement
(DFR) for children and adolescents subsequent to bone tumor resection. Each year in
the US there are 200-250 malignant bone tumor diagnoses in the distal femurs of
patients 15 years and younger. With advances in chemotherapy, limb salvage surgery
utilizing a megaprosthesis has increasingly become the treatment of choice. For
growing patients these megaprostheses are required to extend so they can “grow” as
the contralateral limb grows. Only one non-invasively lengthened DFR is FDA approved
to treat these patients. The implant is actuated with a large electromagnetic appliance in
a clinical setting. It is exceedingly complex and the average revision rate has been
reported at 48%, including revisions for: insufficient lengthening capacity, lengthening
mechanism failure, implant fracture, aseptic loosening and infection. MRI is
contraindicated and the implant is extremely expensive. Our device is non-invasively,
manually extended by pressing on the patient's skin. It's designed for a significantly
reduced complication rate, the mechanism is simple and robust, it's MRI compatible and
can be lengthened at home for a more gradual growth and constant leg length equality.
It is capable of up to 240% of the extension that its sole US competitor offers and is
easier and less expensive to manufacture so it can be offered at a reduced price to a
greater population. The specific aims of the project are to (1) complete the implant
design, (2) design specialized surgical instruments for implantation and (3) conduct non-
clinical bench testing in preparation for FDA submission.

## Key facts

- **NIH application ID:** 10935989
- **Project number:** 5R44AR083875-02
- **Recipient organization:** GRANITE MEDICAL, LLC
- **Principal Investigator:** Jeffrey David Gordon
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $685,746
- **Award type:** 5
- **Project period:** 2023-09-25 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10935989

## Citation

> US National Institutes of Health, RePORTER application 10935989, Non-invasively extendable megaprosthesis (5R44AR083875-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10935989. Licensed CC0.

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