Evaluation of Porous (Poly(lactide-co-glycolide)-co-(ε-caprolactone)) Polyurethane for Use in Orthopedic Scaffolds.

To develop an orthopedic scaffold that could overcome the limitations of implants used in clinics, we designed poly(ester-urethane) foams and compared their properties with those of a commercial gold standard. A degradable poly(ester-urethane) was synthetized by polyaddition between a diisocyanate poly(ε-caprolactone) prepolymer (PCL di-NCO, Mn = 2400 g·mol-1) and poly(lactic-co-glycolic acid) diol (PLGA, Mn = 2200 g·mol-1) acting as a chain extender. The resulting high-molecular-weight poly(ester-urethane) (PEU, Mn = 87,000 g·mol-1) was obtained and thoroughly characterized by NMR, FTIR and SEC-MALS. The porous scaffolds were then processed using the solvent casting (SC)/particle leaching (PL) method with different NaCl crystal concentrations. The morphology, pore size and porosity of the foams were evaluated using SEM, showing interconnected pores with a uniform size of around 150 µm. The mechanical properties of the scaffolds are close to those of the human meniscus (Ey = 0.5~1 MPa). Their degradation under accelerated conditions confirms that incorporating PLGA into the scaffolds greatly accelerates their degradation rate compared to the gold-standard implant. Finally, a cytotoxicity study confirmed the absence of the cytotoxicity of the PEU, with a 90% viability of the L929 cells. These results suggest that degradable porous PLGA/PCL poly(ester-urethane) has potential in the development of meniscal implants.

Collagen/polyester-polyurethane porous scaffolds for use in meniscal repair.

Focusing on the regeneration of damaged knee meniscus, we propose a hybrid scaffold made of poly(ester-urethane) (PEU) and collagen that combines suitable mechanical properties with enhanced biological integration. To ensure biocompatibility and degradability, the degradable PEU was prepared from a poly(ε-caprolactone), L-lysine diisocyanate prepolymer (PCL di-NCO) and poly(lactic-co-glycolic acid) diol (PLGA). The resulting PEU (Mn = 52 000 g mol-1) was used to prepare porous scaffolds using the solvent casting (SC)/particle leaching (PL) method at an optimized salt/PEU weight ratio of 5 : 1. The morphology, pore size and porosity of the scaffolds were evaluated by SEM showing interconnected pores with a uniform size of around 170 µm. Mechanical properties were found to be close to those of the human meniscus (Ey ∼ 0.6 MPa at 37 °C). To enhance the biological properties, incorporation of collagen type 1 (Col) was then performed via soaking, injection or forced infiltration. The latter yielded the best results as shown by SEM-EDX and X-ray tomography analyses that confirmed the morphology and highlighted the efficient pore Col-coating with an average of 0.3 wt% Col in the scaffolds. Finally, in vitro L929 cell assays confirmed higher cell proliferation and an improved cellular affinity towards the proposed scaffolds compared to culture plates and a gold standard commercial meniscal implant.

Noncemented total knee arthroplasty with a local prophylactic anti-infection agent: a prospective series of 135 cases.

BACKGROUND: I conducted a prospective study to assess the effectiveness of an absorbable calcium hydroxyapatite (Hac) layer mixed with vancomycin applied to the articular surface of prosthetic implants in preventing deep infections after noncemented total knee arthroplasty (TKA). This severe complication of TKA occurs in 2%-7% of cases. METHODS: In all, 135 consecutive noncemented TKAs were performed in 126 patients, who were divided into 2 groups. Group 1 comprised 73 knees that received a noncemented implant without any local anti-infection treatment. Group 2 comprised 62 knees that received a noncemented implant with the local anti-infection agent, which consisted of a pasty mixture of 2 g absorbable Hac and 1-2 g vanco mycin. The paste was spread in a thin layer on the articular surface of the implants. Patients in both groups received systemic antibiotic therapy. RESULTS: In group 1 (no local anti-infection agent), there were 3 deep infections (4.1%) in the early (< 2 mo) or intermediate (2 mo to 2 yr) period after surgery, but no signs of loosening. The infections were treated by arthroscopic debridement and antibiotic therapy. There were no infections or loosening of joints in group 2. CONCLUSION: This study shows that a local anti-infection treatment is an effective supplement to systemic antibiotic therapy for the prevention of deep infections in noncemented TKA.