An Increase in Medial Joint Space Width After Medial Open-Wedge High Tibial Osteotomy Is Associated With an Increase in the Postoperative Weight-Bearing Line Ratio Rather Than With Cartilage Regeneration: Comparative Analysis of Patients Who Underwent Second-Look Arthroscopic Assessment.

PURPOSE: To investigate relevant factors influencing increases in medial joint space width (JSW) after medial open-wedge high tibial osteotomy (MOWHTO). METHODS: Between January 2010 and December 2018, the electronic medical records of consecutive patients who underwent MOWHTO and subsequent second-look arthroscopic assessment at least 12 months after MOWHTO were retrospectively evaluated. The patients were classified into 2 groups according to changes in the medial JSW of the knee at the time of the second-look operation compared with that at baseline before the initial surgical procedure. Various radiographic parameters, arthroscopic findings, and clinical scores were compared between the groups, and regression analysis was performed to identify factors related to increases in medial JSW. RESULTS: A total of 114 patients were analyzed. In a bivariate analysis, patients who experienced an increase in medial JSW showed a significantly higher postoperative weight-bearing line ratio (WBLR) (P = .008) and a greater proportion of severe preoperative cartilage lesions in the medial compartment of the knee compared with patients with a maintained or reduced medial JSW (P = .035). In terms of clinical scores, patients with an increased medial JSW showed relatively favorable clinical outcomes at the time of the second-look operation. Regression analysis indicated only postoperative WBLR as a relevant factor associated with an increase in medial JSW after MOWHTO (odds ratio, 1.057; P = .01). Additional analysis with patients reclassified according to the postoperative WBLR showed that as the postoperative WBLR increased, the medial JSW increased, without a significant change in the lateral JSW. CONCLUSIONS: An increase in the medial JSW of the knee joint after MOWHTO appears to be associated with an increase in the postoperative WBLR, not with cartilage regeneration. Obtaining adequate correction so that the postoperative WBLR is within 60% to 70% would be desirable in terms of postoperative changes in the medial JSW, as well as clinical outcomes. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Assessment of the Influence of Acetic Acid Residue on Type I Collagen during Isolation and Characterization.

Various methods for isolation of type I collagen using acids, bases, enzymes, and their combinations have been applied. However, a lack of standardization exists among type I collagens isolated by various approaches. Consequently, in this study, we assessed the influence of acetic acid residue on type I collagen isolated by pepsin-acetic acid treatment, the fabrication of collagen-based porous scaffolds, and the seeded cells on collagen scaffolds. Unlike the isolated collagen dialyzed by deionized water (DDW), collagen dialyzed by 0.5 M acetic acid (DAC) exhibited structural and thermal denaturation. Both DDW- and DAC-based porous scaffolds at all collagen concentrations (0.5, 1 and 2% w/v) showed the high degree of porosity (>98%), and their pore morphologies were comparable at the same concentrations. However, the DDW- and DAC-based collagen scaffolds displayed significant differences in their physical properties (weight, thickness, and volume) and swelling behaviors. In particular, the weight losses induced by mechanical stimulation reflected the high degradation of DAC-collagen scaffolds. In cell culture experiments using adipose-derived stem cells (ADSCs), the characteristics of mesenchymal stem cell (MSC) did not change in both DDW- and DAC-collagen scaffolds for 10 days, although cells proliferated less in the DAC-collagen scaffolds. Our results suggest that the elimination of acetic acid residue from isolated collagen is recommended to produce collagen scaffolds that provide a stable environment for cells and cell therapy-related applications.