A biodegradable polymer is a plastic designed to breakdown and disappear. Inside the body it breaks into small molecules that are absorbed or cleared out, leaving nothing to remove or worry about. This one property changed how surgeons think about implants that a device no longer has to last forever, only long enough.
The clearest benefit of using biodegradable material in healthcare is avoiding a second operation. In a study of 32 tibial tubercle fractures in adolescents, every patient given metal screws returned for removal surgery at an average of 8.8 months. None of the bioabsorbable-screw patients needed that procedure, and hardware irritation fell from 41.2% to 6.7% (Chen et al., 2025).
The rest follows from the same idea. The implant supports tissue while it heals, then steps aside on a tuned schedule. It can carry a drug and release it as it dissolves, or act as a framework for new tissue. Because it vanishes, nobody carries a foreign object for decades.
Key Requirements for Medical-Grade Polymers
- Biocompatibility: The material must demonstrate local and systemic biological safety, remaining within host tissue without eliciting any immune responses in the body.
- Controlled biodegradation: The kinetics of degradation need to be aligned with the tissue regeneration rates to ensure predictable clearance from the host organism.
- Mechanical strength: Structural performance must meet or exceed physiological load-bearing demands throughout the entire healing phase.
- Sterilizability: Physical, chemical, and structural properties of the material must not be compromised by sterilization in an industrial environment.
- Low toxicity: Both the constituent material and any associated additives must maintain non-toxic thresholds within therapeutic dosage ranges.
- Predictable degradation products: Degradation byproducts must undergo predictable metabolic clearance or excretion pathways without secondary toxicity.
- Processability: The material must possess reliable processing characteristics suitable for targeted manufacturing techniques (e.g., electrospinning, injection molding, or additive manufacturing).
- Regulatory compliance: Properties and validation processes must conform to ISO, FDA, or equivalent international regulatory standards for medical devices.
Major Types of Biodegradable Polymers
| Polymer | What it is | Typical medical use |
| PLA / PLLA | Plant-sugar polyester, 30-40% crystalline, high strength | Orthopaedic screws, pins, plates, scaffolds |
| PGA | Fast-degrading polyester | Absorbable sutures |
| PLGA | PLA-PGA copolymer; rate set by monomer ratio | Drug-delivery microspheres and nanoparticles |
| PCL | Slow polyester, roughly 2-4 years to degrade | Long-term scaffolds, nanofibre dressings |
| PHA (incl. P4HB) | Made inside bacteria by fermentation | Absorbable suture, surgical mesh |
| PDO | Flexible polyester, about 55% crystalline | Monofilament absorbable sutures |
| Collagen, chitosan, alginate | Natural polymers the body recognises | Scaffolds, hydrogels, wound dressings |
Sources: Kurowiak et al. (2023); Lu, Y. et al. (2023); Williams et al. (2013).
The Process of Biodegradation
Most medical polyesters break down by hydrolysis. Water works into the amorphous regions, lowers the glass transition temperature, then cuts the ester bonds. Molecular weight falls first, strength follows, mass loss comes last (Lu et al., 2023).
Enzymes speed this up for natural polymers and PHAs. Breakdown can happen mainly at the surface, so the object shrinks while its core stays intact, or through the bulk, so the whole piece weakens at once. That distinction matters more than it sounds.
Longer chains degrade more slowly and higher crystallinity slows water entry. Copolymer ratio is the strongest. PLGA degrades fastest at 50:50 (Lu et al., 2023). Shape, porosity, surface treatment and the local environment decide how fast water and cells reach the material.
PLGA is approved by the FDA and European Authorities as a drug carrier, it is formed into microspheres and nanoparticles that release their payload as the polymer erodes (Lu et al., 2023). One injection can replace weeks of daily doses, and nanoparticle surfaces can steer a drug toward target tissue.
Why PHA Stands Out
Three properties separate PHA from the polyesters that dominate the field.
First, it degrades gently. PLA breaks down by bulk hydrolysis and acidifies the tissue around it. PHA are degraded by enzymes or by surface erosion, wearing away from the outside instead of turning acidic from within.
Second, its breakdown product is already getting produced in human body. 4-hydroxybutyrate, the monomer of P4HB, is a normal compound in the human body and proven biocompatible (Utsunomia et al., 2020).
Third, it bends instead of snapping. P4HB reaches 50 MPa tensile strength at 1,000% elongation. PLLA manages 28 to 50 MPa at 6%, PGA 70 MPa at under 3% (Utsunomia et al., 2020). This flexibility is what the brittle polyesters lack.
Tissue Engineering and Regenerative Medicine
A scaffold is a temporary frame. Cells attach, multiply and lay down their own matrix while it disappears. Porosity makes it work as open, interconnected pores let cells migrate inward and promote bone induction.
Timing is the catch here. A scaffold degrading faster than tissue grows collapses while one that lingers blocks the tissue it was meant to help.
Biodegradable Polymers in Sutures
Absorbable sutures were the first widespread use of these materials and remain the biggest. PGA, PLA-based copolymers and polydioxanone serve here, chosen by how long the wound needs support.
PHA entered in 2007, when the FDA cleared a monofilament suture made from poly-4-hydroxybutyrate, produced by fermentation, with fibres designed for prolonged strength retention in the body (Williams et al., 2013). Meshes followed; Phasix mesh and the P4HB plug fully resorb within 12 to 18 months (Utsunomia et al., 2020).
Orthopaedic Applications
Screws, pins and plates made from PLLA hold bone fragments while they knit together. PLLA is 30% to 40% crystalline with high strength which lets a polymer screw do a metal screw’s job.
Cardiovascular Applications
Bioresorbable vascular scaffolds were designed to keep coronary arteries open, release a drug, and then gradually disappear.
However, pooled data from five randomised trials involving 5,988 patients showed worse outcomes than metal stents. Over five years, target lesion failure occurred in 15.9% of scaffold patients versus 13.1% with metal stents, while device thrombosis was 2.2% versus 1.0%. Most of the excess risk occurred during the first three years, before the scaffold had fully resorbed (Power et al., 2025).
The problem was largely mechanical. PLLA breaks at only 6% elongation, requiring relatively thick struts that can increase clot formation. In contrast, P4HB can stretch by up to 1,000% (Utsunomia et al., 2020), making it a promising material for the next generation of bioresorbable scaffolds.
Wound Healing Application
Electrospun nanofibre dressings have high porosity and surface area and resemble the body’s extracellular matrix. That absorbs wound fluid, blocks bacteria and supports cell growth, while drugs loaded into the fibres release at the wound (Lu et al., 2024). Hydrogels hold moisture at the surface.
3D Printing, Nanotechnology and Personalised Implants
Additive manufacturing lets a surgeon order an implant shaped to patient’s anatomy, with pore size and porosity set by design. At the smaller scale, nanoparticles, nanofibers and nanocomposites improve drug loading and let surfaces be engineered for cell response.
Biocompatibility, Safety and Mechanical Performance
Safety testing checks for cell toxicity, inflammation, immune reactions, foreign-body responses, and harmful degradation products, following ISO 10993 guidelines (Kurowiak et al., 2023).
The material must also maintain strength, elasticity, toughness, and fatigue resistance during healing. Faster degradation often means lower strength, creating a trade-off. P4HB’s combination of strength and flexibility may help overcome this limitation.
Regulatory Requirements
A device is classified by risk first.
Then comes biocompatibility testing under ISO 10993, chemical characterisation, degradation testing, sterility validation and quality control. Regulators scrutinise the degradation data hardest, because the material a patient receives is not what remains six months later.
Future Outlook
Bioabsorbable screws removed the second operation in adolescent fractures (Chen et al., 2025). P4HB reached FDA clearance as a suture in 2007, then mesh resorbing in 12 to 18 months (Williams et al., 2013; Utsunomia et al., 2020). Vascular scaffolds showed a material’s timeline can decide an outcome (Power et al., 2025).
All these shows that the work is moving towards smart materials. Polymers that respond to pH, temperature or enzymes, self-healing networks, and 4D-printed structures that change shape after implantation. Bioactive polymers and polymer-nanoparticle systems follow. PHA, tunable across many monomers, is unusually well placed for that.
Where TerraPHA Fits
TerraPHA Biotech is the World’s first non-GMO biopolymer company producing PHA and PHA-based products for multiple sectors in the market. PHA is produced using naturally occurring non-GMO microbial systems and precision-controlled fermentation across a range of renewable carbon sources.
Biomedical industry lies among the company’s future application areas, pointing to biodegradable biopolymers as safer options for devices and drug delivery.
Frequently Asked Questions
What happens to the material inside the body?
It breaks into molecules the body already handles. PLGA ends as lactic and glycolic acid. P4HB ends as 4-hydroxybutyrate which is already a natural compound produced in the body.
How the degradation time chosen?
It is chosen by design. Copolymer ratio, molecular weight, crystallinity, porosity and surface treatment are tuned to the healing period. PLGA degrades fastest at 50:50; PCL takes two to four years; P4HB mesh resorbs in 12 to 18 months.
References
Chen, T., Wen, Y., Zhu, D., Feng, W., Song, B., & Wang, Q. (2025). Comparison of bioabsorbable screw versus metallic screw fixation for tibial tubercle fractures in adolescents: A retrospective cohort study. BMC Musculoskeletal Disorders, 26, 38. https://doi.org/10.1186/s12891-025-08281-z
Kurowiak, J., Klekiel, T., & Będziński, R. (2023). Biodegradable polymers in biomedical applications: A review—Developments, perspectives and future challenges. International Journal of Molecular Sciences, 24(23), 16952. https://doi.org/10.3390/ijms242316952
Lu, X., Zhou, L., & Song, W. (2024). Recent progress of electrospun nanofiber dressing in the promotion of wound healing. Polymers, 16(18), 2596. https://doi.org/10.3390/polym16182596
Lu, Y., Cheng, D., Niu, B., Wang, X., Wu, X., & Wang, A. (2023). Properties of poly(lactic-co-glycolic acid) and progress of poly(lactic-co-glycolic acid)-based biodegradable materials in biomedical research. Pharmaceuticals, 16(3), 454. https://doi.org/10.3390/ph16030454
Power, D. A., Camaj, A., Kereiakes, D. J., Ellis, S. G., Gao, R., Kimura, T., Ali, Z. A., Stockelman, K. A., Dressler, O., Onuma, Y., Serruys, P. W., & Stone, G. W. (2025). Early and late outcomes with the Absorb bioresorbable vascular scaffold: Final report from the ABSORB clinical trial program. JACC: Cardiovascular Interventions, 18(1), 1-11. https://doi.org/10.1016/j.jcin.2024.08.050
Utsunomia, C., Ren, Q., & Zinn, M. (2020). Poly(4-hydroxybutyrate): Current state and perspectives. Frontiers in Bioengineering and Biotechnology, 8, 257. https://doi.org/10.3389/fbioe.2020.00257
Williams, S. F., Rizk, S., & Martin, D. P. (2013). Poly-4-hydroxybutyrate (P4HB): A new generation of resorbable medical devices for tissue repair and regeneration. Biomedizinische Technik/Biomedical Engineering, 58(5). https://doi.org/10.1515/bmt-2013-0009
