Cartilage diseases

Abstract

Hyaline cartilages, fibrocartilages and elastic cartilages play multiple roles in the human body including bearing loads in articular joints and intervertebral discs, providing joint lubrication, forming the external ears and nose, supporting the trachea, and forming the long bones during development and growth. The structure and organization of cartilage's extracellular matrix (ECM) are the primary determinants of normal function. Most diseases involving cartilage lead to dramatic changes in the ECM which can govern disease progression (e.g., in osteoarthritis), cause the main symptoms of the disease (e.g., dwarfism caused by genetically inherited mutations) or occur as collateral damage in pathological processes occurring in other nearby tissues (e.g., osteochondritis dissecans and inflammatory arthropathies). Challenges associated with cartilage diseases include poor understanding of the etiology and pathogenesis, delayed diagnoses due to the aneural nature of the tissue and drug delivery challenges due to the avascular nature of adult cartilages. This narrative review provides an overview of the clinical and pathological features as well as current treatment options available for various cartilage diseases. Late breaking advances are also described in the quest for development and delivery of effective disease modifying drugs for cartilage diseases including osteoarthritis, the most common form of arthritis that affects hundreds of millions of people worldwide.

Keywords: Cartilage; Cartilage ECM-targeted drug carriers; Chondrocalcinosis; Diseases of cartilage; Extracellular matrix; Genetic disorders involving cartilage; Growth plate fractures; Inflammatory arthropathies; Osteoarthritis; Osteochondritis dissecans; Post-traumatic osteoarthritis; Pseudogout cartilaginous tumors; Relapsing polychondritis.

Figure 1. Anatomical locations and microscopic structure of cartilage

(a) Locations of hyaline cartilage (blue), fibrocartilage (yellow) and elastic cartilage (red) in the human body; (b) Immature bovine articular cartilage; (c) Human adult articular cartilage (83 year old male donor distal femur) showing chondrocyte clustering near the tidemark, typical of osteoarthritis; (d) Murine fibrous cartilage (FC) at the interface of the supraspinatus tendon (T) and the humeral head of the humerus bone (B); (e) Elastic cartilage of neonatal bovine ear; elastin fibers appear as unstained lines between the safranin-O staining for GAGs

Figure 2

Macroscopic cartilage degradation in human femoral cartilage caused by osteoarthritis