Acellular Cartilage Repair Technique Based on Ultrapurified Alginate Gel Implantation for Advanced Capitellar Osteochondritis Dissecans

Osteochondritis dissecans of the elbow: recent evolution of pathogenesis, imaging, and treatment modalities

Background

The etiology and pathogenesis of osteochondritis dissecans (OCDs) lesions remain controversial.

Methods

This review presents the recent evolution about the healing, imaging, pathogenesis, and how to treat OCD of the capitellum in overhead athletes.

Results

Compressive and shear forces to the growing capitellum can cause subchondral separation, leading to OCD, composed of 3 layers: articular fragment, gap, and underlying bone. Subchondral separation can cause ossification arrest (stage IA), followed by cartilage degeneration (stage IB) or delayed ossification (stage IIA), occasionally leading to osteonecrosis (stage IIB) in the articular fragment. Articular cartilage fracture and gap reseparation make the articular fragment unstable. The mean tilting angle of capitellar OCD is 57.6 degrees in throwers. Anteroposterior radiography of the elbow at 45 degrees of flexion (APR45) can increase the diagnostic reliability, showing OCD healing stages, as follows: I) radiolucency, II) delayed ossification, and III) union. Coronal computed tomography and magnetic resonance imaging with an appropriate tilting angle can also increase the reliability. MRI is most useful to show the instability, although it occasionally underestimates. Sonography contributes to detection of early OCD in adolescent throwers on the field. OCD lesions in the central aspect of the capitellum can be more unstable and may not heal. Cast immobilization has a positive effect on healing for stable lesions. Arthroscopic removal provides early return to sports, although a large osteochondral defect is associated with a poor prognosis. Fragment fixation, osteochondral autograft transplantation, and their hybrid technique have provided better results.

Discussion

Further studies are needed to prevent problematic complications of capitellar OCD, such as osteoarthritis and chondrolysis.

Osteochondritis Dissecans of the Elbow in Overhead Athletes: A Comprehensive Narrative Review

Osteochondritis dissecans (OCD) of the elbow mainly occurs in overhead athletes (OHAs). This narrative review aimed to comprehensively analyze the epidemiological data, etiological factors, clinical and imaging features, treatment options, and outcomes of OHAs with the diagnosis of elbow OCD. A literature search was performed in PubMed/MEDLINE, Scopus, and Web of Science. Individuals with elbow OCD were usually 10-17 years of age with incidence and prevalence varying between studies, depending on the sport activity of the patients. The etiology of OCD lesions is multifactorial, and the main causes are believed to be repetitive trauma, the biomechanical disproportion of the articular surfaces, poor capitellar vascular supply, and inflammatory and genetic factors. Athletes usually presented with elbow pain and mechanical symptoms. The mainstay for the diagnosis of elbow OCD is MRI. The treatment of elbow OCD lesions should be conservative in cases of stable lesions, while various types of surgical treatment are suggested in unstable lesions, depending mainly on the size and localization of the lesion. The awareness of medical practitioners and the timely diagnosis of OCD lesions in OHAs are key to favorable outcomes.

Neo-cartilage formation using human nondegenerate versus osteoarthritic chondrocyte-derived cartilage organoids in a viscoelastic hydrogel

Current regenerative cartilage therapies are associated with several drawbacks such as dedifferentiation of chondrocytes during expansion and the formation of fibrocartilage. Optimized chondrocyte expansion and tissue formation could lead to better clinical results of these therapies. In this study, a novel chondrocyte suspension expansion protocol that includes the addition of porcine notochordal cell-derived matrix was used to self-assemble human chondrocytes from osteoarthritic (OA) and nondegenerate (ND) origin into cartilage organoids containing collagen type II and proteoglycans. Proliferation rate and viability were similar for OA and ND chondrocytes and organoids formed had a similar histologic appearance and gene expression profile. Organoids were then encapsulated in viscoelastic alginate hydrogels to form larger tissues. Chondrocytes on the outer bounds of the organoids produced a proteoglycan-rich matrix to bridge the space between organoids. In hydrogels containing ND organoids some collagen type I was observed between the organoids. Surrounding the bulk of organoids in the center of the gels, in both OA and ND gels a continuous tissue containing cells, proteoglycans and collagen type II had been produced. No difference was observed in sulphated glycosaminoglycan and hydroxyproline content between gels containing organoids from OA or ND origin after 28 days. It was concluded that OA chondrocytes, which can be harvested from leftover surgery tissue, perform similar to ND chondrocytes in terms of human cartilage organoid formation and matrix production in alginate gels. This opens possibilities for their potential to serve as a platform for cartilage regeneration but also as an in vitro model to study pathways, pathology, or drug development.

Application of Alginate Hydrogels for Next-Generation Articular Cartilage Regeneration

The articular cartilage has insufficient intrinsic healing abilities, and articular cartilage injuries often progress to osteoarthritis. Alginate-based scaffolds are attractive biomaterials for cartilage repair and regeneration, allowing for the delivery of cells and therapeutic drugs and gene sequences. In light of the heterogeneity of findings reporting the benefits of using alginate for cartilage regeneration, a better understanding of alginate-based systems is needed in order to improve the approaches aiming to enhance cartilage regeneration with this compound. This review provides an in-depth evaluation of the literature, focusing on the manipulation of alginate as a tool to support the processes involved in cartilage healing in order to demonstrate how such a material, used as a direct compound or combined with cell and gene therapy and with scaffold-guided gene transfer procedures, may assist cartilage regeneration in an optimal manner for future applications in patients.