Polyurethane Meniscal Scaffold: Does Preoperative Remnant Meniscal Extrusion Have an Influence on Postoperative Extrusion and Knee Function?

Meniscal extrusion (ME) has been identified as a risk factor in the development of knee osteoarthritis. The relevance of this finding when a meniscal scaffold is used has not been extensively studied. The objective of this study was to determine whether preoperative meniscal remnant extrusion (MRE) was correlated with postoperative scaffold extrusion (SE) or with functional outcomes at the 2-year follow-up. Retrospective study included all polyurethane scaffolds implanted with a minimum 2-year follow-up. A magnetic resonance imaging (MRI) was performed preoperatively and postoperatively at 2 years. Extrusion was measured in millimeters in a coronal view. Patients were assigned to either group 1 or 2 depending on the preoperative MRE being either <3 mm (minor extrusion) or 3 mm (major extrusion). Functional outcomes were analyzed by means of the Western Ontario Meniscal Evaluation Tool (WOMET), International Knee Documentation Committee, Kujala and Tegner scores, as well as visual analog scale. Satisfaction was also documented. Sixty-two out of 98 patients were available to undergo an MRI at final follow-up. The mean age was 41.3 years (range, 17–58) and the mean follow-up was 45 months (range, 25–69). The mean preoperative MRE was 2.8 mm (standard deviation [SD] 1.2) and the mean postoperative SE was 3.8 mm (SD 1.8) (p < 0.01). All functional scores improved during the study period. When the correlation (Spearman's rho) between the difference in extrusion between the pre 26 and postoperative periods and their correlation with the different scores was assessed, correlation was only observed in the WOMET (rho 0.61, p = 0.02). The preoperative MRE in Group 1 was 1.85 mm (SD 0.83) and 3.7 mm (SD 2.2) in Group 2 (p < 0.01). At final follow-up, SE was 3.86 mm (SD 0.7) in Group 1, whereas it was 3.98 mm (SD 1) in Group 2 (p = 0.81). No differences were observed in the scores used for these two groups. The SE observed at the 2-year follow-up after the implantation of a polyurethane scaffold did not depend on preoperative MRE (major or minor extrusion). The WOMET score, which was the only meniscal-specific functional scored used, showed some inferior results in the most extruded meniscal scaffolds. This is a retrospective case series. Level of evidence is 4.

Evaluation of Meniscal Regeneration in a Mini Pig Model Treated With a Novel Polyglycolic Acid Meniscal Scaffold

Background: Meniscal injury is a severe impediment to movement and results in accelerated deterioration of the knee joint. Purpose: To evaluate the effect of a novel meniscal scaffold prepared from polyglycolic acid coated with polylactic acid/caprolactone on the treatment of meniscal injury in a mini pig model. Study Design: Controlled laboratory study. Methods: The model was established with a 10-mm resection at the anterior medial meniscus on both knee joints. A scaffold was implanted in the right knee joint. The meniscal scaffold was inserted and sutured next to the native meniscus. The histological analysis was performed to determine meniscal regeneration with safranin O staining, cell proliferation with PCNA, inflammation with TNF, and collagen structure and production with picrosirius red and immunofluorescence. Cartilage degeneration was evaluated with Safranin O. Meniscal regeneration and joint fluid were evaluated with magnetic resonance imaging. Results: Although compressive stress and elastic modulus were significantly lower in the scaffold than in the native porcine menisci, ultimate tensile stress was similar. Implanted scaffolds were covered with tissue beginning at 4 weeks, with increased migration of proliferating cells to the implant area at 4 and 8 weeks. Scaffolds were absorbed with freshly produced collagen at 24 weeks. Cartilage degeneration was significantly lower in the meniscus-implanted group than in the meniscectomy group. Magnetic resonance imaging results did not show severe accumulation of joint fluids, suggesting negligible inflammation. Density of the implanted menisci was comparable with that of the native menisci. Conclusion: Meniscal scaffold prepared from polyglycolic acid has therapeutic potential for meniscal regeneration. Clinical Relevance: This meniscal scaffold can improve biological knee reconstruction and prevent the increase of total knee arthroplasty.