Objective:We tested whether an intra-articular ultrasound (IAUS) method could be used to evaluate cartilage status arthroscopically in human knee joints in vivo.Design:Seven patients undergoing arthroscopic surgery of the knee were enrolled in this study. An ultrasonic examination was conducted using the same portals as in the arthroscopic surgery. A high-frequency (40-MHz) ultrasound transducer (diameter = 1 mm) was directed to the desired location on the articular surface under arthroscopic control. In addition to ultrasound data, an IAUS video and optical video through the arthroscope were recorded. Classification of cartilage injuries according to International Cartilage Repair Society, as conducted by the orthopedic surgeon, provided reference data for comparison with the IAUS.Results:The IAUS method was successful in imaging different characteristics of the articular surfaces (e.g., intact surface, surface fibrillation, and lesions of varying depth). In some cases, also the subchondral bone and abnormal internal cartilage structure were visible in the IAUS images. Specifically, using the IAUS, a local cartilage lesion of 1 patient was found to be deeper than estimated arthroscopically.Conclusions:The IAUS method provided a novel arthroscopic method for quantitative imaging of articular cartilage lesions. The IAUS provided quantitative information about the cartilage integrity and thickness, which are not available in conventional arthroscopy. The present equipment is already approved by the Food and Drug Administration for intravascular use and might be transferred to intra-articular use. The invasiveness of the IAUS method might restrict its wider clinical use but combined with arthroscopy, ultrasonic assessment may enlarge the diagnostic potential of arthroscopic surgery.

The purpose of this study was to investigate the potential of a novel recombinant human type II collagen/polylactide scaffold (rhCo-PLA) in the repair of full-thickness cartilage lesions with autologous chondrocyte implantation technique (ACI). The forming repair tissue was compared to spontaneous healing (spontaneous) and repair with a commercial porcine type I/III collagen membrane (pCo). Domestic pigs (4-month-old, n ¼ 20) were randomized into three study groups and a circular full-thickness chondral lesion with a diameter of 8 mm was created in the right medial femoral condyle. After 3 weeks, the chondral lesions were repaired with either rhCo-PLA or pCo together with autologous chondrocytes, or the lesion was only debrided and left untreated for spontaneous repair. The repair tissue was evaluated 4 months after the second operation. Hyaline cartilage formed most frequently in the rhCo-PLA treatment group. Biomechanically, there was a trend that both treatment groups resulted in better repair tissue than spontaneous healing. Adverse subchondral bone reactions developed less frequently in the spontaneous group (40%) and the rhCo-PLA treated group (50%) than in the pCo control group (100%). However, no statistically significant differences were found between the groups. The novel rhCo-PLA biomaterial showed promising results in this proof-of-concept study, but further studies will be needed in order to determine its effectiveness in articular cartilage repair. 2,3 However, the original ACI procedure where a periosteal flap covers the repair area has major intrinsic limitations, such as initial mechanical weakness of the repaired site and periosteal hypertrophy. 4A wide variety of biomaterials have been introduced for cartilage repair as periosteal flap substitutes in ACI.5-8 Our research group has developed a novel biomaterial scaffold rhCo-PLA, which is a biodegradable scaffold combining recombinant human type II collagen (rhCo) and polylactide 96/4 felt (PLA). Being free of animal products, rhCo-PLA scaffold eliminates the risk of undesirable immunological responses and transmission of animal-derived pathogens.9,10 We have demonstrated the biocompatibility and neocartilage forming ability of recombinant human type II collagen.11,12 Furthermore, the recombinant technology enables batch consistency and manufacture of high purity collagen. The synthetic polylactide can be fabricated into a 3D scaffold structure that provides the repair site with mechanical support while gradually degrading as neotissue forms. However, PLAs alone have limitations in bioactivity. This is typically seen as a dense connective tissue layer around the PLA. 13 The rhCo, in contrast, is incorporated in the synthetic PLA mesh to improve its physico-chemical and biomechanical characteristics. Collagen enhances hydrophilicity of a scaffold. 6,14 Mechanical loading pumps water out of cartilage tissue, and during unloading, the water is reabsorbed. Thus, the water reabsorbing ability is an essential characteristic of a scaffold. W...

The International Cartilage Repair Society (ICRS) score and the Oswestry Arthroscopic Score (OAS) have been validated to evaluate repair tissue quality. However, the performance of these scores has not been studied in typical patients undergoing cartilage repair and who have lesions of varying sizes. In this study, we compared the performance of the ICRS and the OAS scores and analyzed the effect of lesion characteristics on the performance of these two scores. Cartilage repair quality was assessed in a total of 104 arthroscopic observations of cartilage repair sites of the knee in 62 patients after autologous chondrocyte implantation. Two observers scored the repair areas independently with the ICRS and the OAS scores. The performance of both scores was evaluated according to internal consistency and inter‐rater reliability and correlation between the scores. The frequency and proportion of disagreements were analyzed according to the repair site area and the given score. The correlation between the scores was good (r = 0.91, 95% confidence interval [CI]: 0.87–0.94). Both scores showed moderate internal consistency and inter‐rater reliability. Cronbach's α was 0.88 (95% CI: 0.80–0.92) for the ICRS score and 0.79 (95% CI: 0.70–0.86) for the OAS score. The intraclass correlation coefficient was 0.89 (95% CI: 0.84–0.92) for the ICRS and 0.81 (95% CI: 0.74–0.87) for the OAS scores. The frequency and proportion of disagreements were higher in larger repair sites. In arthroscopic use, both ICRS and OAS scores perform similarly, however, their reliability deteriorates as the lesion size increases. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:555–562, 2020

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