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Polydioxanone biodegradable pins in the knee: MR imaging
C B Sirlin1, R D Boutin, J Brossmann
1Department of Radiology, UCSD Medical Center, 200 W. Arbor Dr., San Diego, CA 92103, USA.
AJR. American Journal of Roentgenology
|January 3, 2001
Summary
Biodegradable polydioxanone pins used in knee surgery typically resorb within 24 months. Associated inflammation and cartilage defects are infrequent and usually resolve, indicating successful bone integration.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Radiology
Background:
- Metallic implants pose risks like stress shielding and implant loosening.
- Biodegradable implants offer a promising alternative, degrading and integrating with bone over time.
- Polydioxanone (PDS) pins are used for osteochondral allograft fixation.
Purpose of the Study:
- To document the resorption and integration of biodegradable polydioxanone pins in human patients using MR imaging.
- To assess the incidence and resolution of associated inflammatory changes and cartilage defects.
Main Methods:
- 175 polydioxanone pins were used in 59 knee osteochondral allografts.
- Patients underwent serial MR imaging (1.5-T) at multiple time points (3-36 months).
- Two osteoradiologists evaluated pin channel visibility, bone replacement, marrow edema, and cartilage defects.
Main Results:
- Over 80% of pin channels were visible at 3-6 months; only 20% remained by 24 months.
- Marrow edema decreased from 40% at 3 months to <20% later.
- Cartilage defects at insertion sites decreased from 32% in the first 6 months to 4% thereafter.
Conclusions:
- Biodegradable polydioxanone pins generally resorb completely by 24 months.
- Inflammation and cartilage defects related to these pins are infrequent and tend to resolve spontaneously.
- MR imaging effectively visualizes the resorption and integration of biodegradable orthopedic implants.