Retrospective comparative study, Level III.

HA promoted human meniscus regeneration by inhibiting apoptosis, promoting cell migration, and accelerating cell proliferation, potentially through the PI3K/MAPK pathway via the CD44 receptor.

Medial opening-wedge high tibial osteotomy (OWHTO) induces a lower patellar position, and the subsequent degree of patellar movement may not be predicted preoperatively. The purpose of this study was to clarify the relationship between preoperative and postoperative patellar height based on the correction angle of OWHTO and to create a formula to predict the appearance of patella baja following OWHTO. Materials and Methods: Seventy-five knees with varus knee osteoarthritis treated with OWHTO were included in this study. The Caton-Deschamps index was used to evaluate patellar height preoperatively and postoperatively, and the cutoff value for preoperative parameters was determined by a receiver operating characteristic curve to determine the risk ratio for postoperative patella baja. Results: The Caton-Deschamps index significantly decreased from 0.93 to 0.77 after OWHTO (p < 0.01). The OWHTO correction angle negatively correlated with the delta Caton-Deschamps index (r ¼ À0.44, p < 0.01), and a 1.7% decrease in the Caton-Deschamps index was shown with a 1 correction angle. Receiver operating characteristic curve analysis revealed that a Caton-Deschamps index of 0.8 was the cutoff for OWHTO; knees with a preoperative Caton-Deschamps index of < 0.8 tended to develop patella baja after OWHTO, with a risk ratio of 9.5 (95% confidence interval [4.3-20.7]). Conclusions: OWHTO can induce patella baja, and a 1.7% decrease in the Caton-Deschamps index was shown with a 1-correction angle. A preoperative Caton-Deschamps index < 0.8 should be considered a risk factor for postoperative patella baja.

IV. Retrospective case series study.

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.