Anionic Contrast-Enhanced MicroCT Imaging Correlates with Biochemical and Histological Evaluations of Osteoarthritic Articular Cartilage

A Cationic Contrast Agent in X-ray Imaging of Articular Cartilage: Pre-Clinical Evaluation of Diffusion and Attenuation Properties

The aim of this study was the preliminary assessment of a new cationic contrast agent, the CA4+, via the analysis of spatial distribution in cartilage of ex vivo bovine samples, at micrometer and millimeter scale. Osteochondral plugs (n = 18) extracted from bovine stifle joints (n = 2) were immersed in CA4+ solution up to 26 h. Planar images were acquired at different time points, using a microCT apparatus. The CA4+ distribution in cartilage and saturation time were evaluated. Tibial plates from bovine stifle joints (n = 3) were imaged with CT, before and after 24 h-CA4+ bath immersion, at different concentrations. Afterward, potential CA4+ washout from cartilage was investigated. From microCT acquisitions, the CA4+ distribution differentiated into three distinct layers inside the cartilage, reflecting the spatial distribution of proteoglycans. After 24 h of diffusion, the iodine concentration reached in cartilage was approximately seven times that of the CA4+ bath. The resulting saturation time was 1.9 ± 0.9 h and 2.6 ± 2.9 h for femoral and tibial samples, respectively. Analysis of clinical CT acquisitions confirmed overall contrast enhancement of cartilage after 24 h immersion, observed for each CA4+ concentration. Distinct contrast enhancement was reached in different cartilage regions, depending on tissue’s local features. Incomplete but remarkable washout of cartilage was observed. CA4+ significantly improved cartilage visualization and its qualitative analysis.

Autologous Platelet-Rich Fibrin Membrane to Augment Healing of Microfracture Has Better Macroscopic and Histologic Grades Compared With Microfracture Alone on Chondral Defects in a Rabbit Model

PURPOSE

To determine the in vivo effectiveness of a single-stage surgical procedure that combines microfracture and an autologous platelet-rich fibrin (PRF) membrane for cartilage repair in a rabbit model.

METHODS

Cartilage defects were created in the trochlear groove of the knees of adult white rabbits. Defects were divided into 2 treatment groups: microfracture only (control group) and microfracture covered by a PRF membrane (PRF group). To evaluate the repair cartilage, assessments were performed at 4, 12, and 24 weeks postoperatively using the International Cartilage Repair Society (ICRS) macroscopic scoring system and modified Wakitani histologic grading system.

RESULTS

The mean ICRS macroscopic scores in the control and PRF groups were 4.1 and 5.8, respectively, at 4 weeks (P = .0623); 6.3 and 9.8, respectively, at 12 weeks (P = .006); and 6.5 and 10.3, respectively, at 24 weeks (P = .010). The mean modified Wakitani scores in the control and PRF groups were 4.0 and 3.9, respectively, at 4 weeks (P > .999); 5.3 and 10.4, respectively, at 12 weeks (P = .006); and 2.6 and 7.4, respectively, at 24 weeks (P = .012).

CONCLUSIONS

The ICRS macroscopic scores and modified Wakitani scores showed that a single-stage surgical procedure combining microfracture and a PRF membrane was more effective than surgery with only microfracture for promoting cartilage repair.

CLINICAL RELEVANCE

A single-stage surgical procedure combining microfracture and an autologous PRF membrane is a potentially beneficial treatment method for cartilage defects that does not require using any xenocollagen membrane.

Subchondral bone microenvironment in osteoarthritis and pain

Osteoarthritis comprises several joint disorders characterized by articular cartilage degeneration and persistent pain, causing disability and economic burden. The incidence of osteoarthritis is rapidly increasing worldwide due to aging and obesity trends. Basic and clinical research on osteoarthritis has been carried out for decades, but many questions remain unanswered. The exact role of subchondral bone during the initiation and progression osteoarthritis remains unclear. Accumulating evidence shows that subchondral bone lesions, including bone marrow edema and angiogenesis, develop earlier than cartilage degeneration. Clinical interventions targeting subchondral bone have shown therapeutic potential, while others targeting cartilage have yielded disappointing results. Abnormal subchondral bone remodeling, angiogenesis and sensory nerve innervation contribute directly or indirectly to cartilage destruction and pain. This review is about bone-cartilage crosstalk, the subchondral microenvironment and the critical role of both in osteoarthritis progression. It also provides an update on the pathogenesis of and interventions for osteoarthritis and future research targeting subchondral bone.