Biodegradable Fixation in Orthopedics
Most fracture hardware is metal, and most metal hardware eventually comes out. Removal surgery means a second operation with added cost, anesthesia risk, and recovery time. Bioresorbable implants eliminate that step.
Two further reasons drive absorbable fixation. Stress shielding: a stiff titanium plate carries load the healing bone would otherwise bear, and bone responds to reduced loading by losing density, whereas a degrading polymer transfers load back as it resorbs. Imaging: PLA produces essentially no artifact on MRI and CT.
Applications span displaced fractures, ligament repairs, and osteotomies, particularly in the ankle, foot, hand, and knee. The implant only needs to hold the construct until union, typically six to twelve weeks.
PLA-Based Bone Fixation Products
Poly-L-lactide (PLLA) is the workhorse of this category. PLLA pins and screws have been sold under names such as BIOFIX, ActivaPin, and SmartNail, with clinical literature reaching back to the 1980s. Early work by Böstman and colleagues on absorbable ankle fracture fixation established the safety profile later products built on.
Copolymers of PLLA with polyglycolide (PGA) or D,L-lactide tune degradation rate and mechanical properties. PLLA devices are used for small bone fixation in the foot and hand, malleolar ankle fractures, and ACL reconstruction, where PLLA bio-interference screws fix soft tissue grafts in bone tunnels. The FDA has cleared multiple PLLA interference screws for this application.
How PLA Implants Degrade
PLA degrades by hydrolysis, not enzymatic digestion. Water cleaves the ester bonds of the polymer chain into shorter segments until lactic acid remains. That lactic acid is a normal metabolite: it enters the Krebs cycle and is excreted as carbon dioxide and water.
Timeline depends on crystallinity, molecular weight, and geometry. Amorphous low-molecular-weight copolymers can lose strength in weeks; high-molecular-weight PLLA can persist 24 to 36 months. Clinicians care less about total resorption than the strength retention curve, the period during which the implant still holds load. A well-designed PLLA screw retains meaningful strength for three to six months.
PLLA vs PDLLA vs PHA
The two PLA stereoisomers behave differently because of chain packing. PLLA is semicrystalline: ordered regions give it stiffness and strength, and water penetrates crystalline domains reluctantly, so degradation is slower. PDLLA, the racemic D,L form, is amorphous, degrades faster, and is often used for drug delivery or as a blending partner rather than for load-bearing screws. PLLA/PGA copolymers shorten degradation for smaller implants.
PHA is frequently compared with PLA in sustainable packaging, but in bone fixation it remains at the research stage; PLA is the polymer with marketed orthopedic devices and a long clinical record. Titanium remains the reference standard where immediate weight bearing or large structural loads are expected.
Clinical Evidence and Caveats
Decades of follow-up show PLLA fixation performs well in appropriately selected patients. Rare complications include late foreign body reactions, osteolysis, and sterile sinus formation, most often reported with fast-degrading PGA-rich copolymers in the 1980s and 1990s; modern high-molecular-weight PLLA devices have a substantially lower reported incidence. Absorbable screws should not replace metal in high-load diaphyseal fractures.
For procurement and clinical teams evaluating any resorbable implant, the questions are consistent. Is the device cleared by a recognized regulator? Does it meet ISO 10993 biological evaluation requirements? Are degradation and strength-retention studies published, with clinical outcome data beyond the manufacturer's testing?
The same material logic extends to the non-implant side of the operating room. CliniEco supplies PLA-based consumables that support sustainability goals without touching clinical safety: PLA biodegradable isolation gowns, PLA biodegradable waste bags, and disposable bouffant caps. For a broader view, see our guide to what PLA plastic is and how it is used in healthcare.
If your OR reprocesses its own instrumentation, a trial five-pack of biological indicators gives you a month of daily spore tests to start the log.
Related Reading
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- PLA Shoe Covers: Biodegradable Footwear Protection for OR and Clinic
- PLA Bouffant Caps: Compostable Hair Covers for Cleanroom and Clinic
Frequently Asked Questions
Are PLA screws as strong as metal?
No, and they are not designed to be. PLLA interference screws and pins have lower initial strength than titanium or stainless steel, but their strength retention is engineered to outlast the healing period. They are selected where the construct does not need metal-grade rigidity.
How long until PLA screws dissolve?
Total resorption ranges from roughly 12 to 36 months depending on molecular weight, crystallinity, and geometry. Load-bearing strength is lost much earlier, typically within three to six months, and that property determines clinical success.
Are PLA implants safe in the body?
PLA degrades into lactic acid, a normal metabolite processed through the Krebs cycle into carbon dioxide and water. Regulatory clearance, including ISO 10993 biological evaluation, and decades of published clinical use support the safety profile. Patient selection and indication remain the deciding factors.
Last updated: September 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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