Functionally-graded biodegradable scaffold for osteonecrosis treatment
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Solution Overview
Problem
Current treatments for early-stage osteonecrosis of the hip, such as vascularized fibula grafts and porous tantalum metal implants, face limitations including pain, infection risk, donor site morbidity, and inadequate vascularization and bone ingrowth, leading to progressive pain and eventual need for total hip replacement.
Innovation Solution
A biodegradable, functionally-graded scaffold with spatiotemporally-controlled degradation and mechanical properties is used for reconstitution of the osteonecrotic area, composed of three sections with varying porosity and mechanical strength to mimic cortical and trabecular bone, fabricated using additive manufacturing, allowing for customization and integration of growth factors or cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If porous tantalum metal implant is used for early stage ONH treatment, then mechanical support is provided, but vascular invasion and bone ingrowth are minimal leading to progressive pain and clinical failure
Solution Approach 1:
The scaffold employs spatially-graded porosity with distinct regions: proximal segment (15-30% porosity) for mechanical support, middle segment (40-60% porosity) for vascularization, and distal segment (30-50% porosity) for bone ingrowth. This local differentiation allows each region to optimize its function while the entire structure integrates all requirements.
Solution Approach 2:
The invention uses composite materials including poly(ε-caprolactone) (PCL), β-tricalcium phosphate (β-TCP), hydroxyapatite, and polylactic acid (PLA) to create a scaffold that combines mechanical strength with bioactivity. The composite structure enables both load-bearing capacity and enhanced vascular/bone integration.
2Reliability
If vascularized fibula graft is used for ONH treatment, then bone reconstruction is achieved, but pain associated with graft harvesting and donor site morbidity occur
Solution Approach 1:
The invention extracts the problematic element (autologous bone graft harvesting) and replaces it with a biodegradable scaffold that can be fabricated using additive manufacturing. The scaffold is implanted alone without requiring vascularized fibula harvesting, thereby eliminating donor site morbidity while maintaining bone reconstruction capability.
Solution Approach 2:
The scaffold is designed as a biodegradable, disposable implant that performs its function temporarily and then degrades to allow natural bone healing. This eliminates the need for complex, long-term vascularized grafts and their associated harvesting pains.
3Object-affected harmful factors
If core decompression is performed for early stage ONH, then pain is relieved, but prevention of collapse is inconsistent with success rates ranging from 20-70%
Solution Approach 1:
The scaffold is implanted during the early stage of ONH (pre-collapse) to provide immediate mechanical support and biological stimulation. The spatially-graded structure is pre-configured to simultaneously address mechanical stability and biological regeneration, improving the reliability of collapse prevention compared to traditional core decompression alone.
Data Source
AI summary
An engineered medical device for treatment of osteonecrosis is provided where the size, porosity and ceramic content of the device can be personalized based on an individual patient's anatomical and physiological condition. The device distinguishes different segments mimicking anatomically-relevant cortical and cancellous segments, in which the cortical segments of the device can sustain mechanical loading, and the cancellous segment of the device can promote bone ingrowth, osteogenesis and angiogenesis.