Bioresorbable materials are a class of polymers and ceramics that can safely degrade and dissolve in the body over time after fulfilling their intended function. These materials are engineered to degrade at a rate corresponding to the healing process so that they do not remain as permanent foreign bodies in tissue. Common bioresorbable polymers used for implants include polylactic acid (PLA), polyglycolic acid (PGA), and polycaprolactone (PCL). When implanted, these materials slowly break down into natural metabolites - lactic acid and glycolic acid - that can be excreted through normal metabolic pathways. Bioresorbable ceramics like calcium phosphate are also used as they degrade into calcium and phosphate ions essential for bone healing.
There are several key benefits of using them instead of permanent metallic ones. Firstly, as they degrade, they eliminate the need for any future implant removal surgeries. This reduces lifelong risks, recovery time, and costs associated with implant removal. Secondly, as the implants dissolve over time, they allow natural tissues to regenerate in place without any foreign body. For applications in pediatric patients, this circumvents issues with growth constraints from permanent implants. Bioresorbable implants also minimize stress shielding effects and implant-related complications like infection at the implantation site in the long run. As the load is transferred back to the tissue, it enhances bone regeneration. Their degradation profile can be tailored to match tissue healing kinetics thereby providing mechanical support only during the critical healing phase.
Application in Orthopedic Fixation Devices
Bioresorbable Implants have widespread applications in orthopedic surgery. They are commonly used as fixation devices like screws, pins, rods or plates to stabilize bone fractures and facilitate new bone growth. Traditionally, fixation of small bone fractures employed the use of metallic implants like titanium that remained in the body permanently. However, bioresorbable implants have fully replaced them in many cases. For example, PLA screws and pins are routinely used in hand, foot, facial and cranial surgeries. They provide the needed stability for 6-12 months until fracture healing is complete, after which they safely dissolve without requiring follow up surgeries. For large bone fractures, bioresorbable rods, plates, and screws made of composites or PLA/PGA copolymers structurally support bone for 12-24 months and then degrade.
Use in Other Specialties
Bioresorbable implants have widespread applicability beyond orthopedics. In plastic and reconstructive surgery, they are used for temporary wound closure and soft tissue repairs instead of sutures and staples. As they degrade, they alleviate discomfort associated with foreign body removal. In dentistry, bioresorbable membranes made of collagen are placed over bone grafts to aid guided tissue regeneration and bone formation in jaw reconstruction. They selectively allow new bone cells while preventing soft tissue invasion. Similarly, in neurosurgery, bioresorbable polymers are evaluated as temporary barriers to minimize brain scar tissue formation post-surgery. Their tailored degradation helps control drug release for applications in drug-eluting bioresorbable stents and implants. Overall, bioresorbable technology enables minimally invasive procedures with lifelike regeneration outcomes across many clinical specialties.
Regulatory Approval and Commercialization Challenges
Despite clear advantages, bioresorbable implants are still not universally adopted in clinical practice. One major hurdle is the stringent regulatory approval process for materials designed to degrade inside the body. Extensive preclinical and clinical testing is required to demonstrate biocompatibility, appropriate resorption profile, desired mechanical properties over time and safety. Only a few bioresorbable polymer formulations and devices have received approval so far from regulatory agencies like the FDA. High research and development costs add to the final product cost, making widespread adoption challenging. Educating surgeons about subtle differences from metallic devices and addressing perceived risks also requires time and effort. Standardized performance benchmarks need to be established via consensus protocols. With continued innovation and growing clinical evidence, bioresorbable implants are poised to replace traditionals and drive a new generation of regenerative medical solutions.
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