Subchondral geodes - also known as subarticular pseudocysts, subchondral cysts or more simply bone cysts - represent an important sign of osteoarthritis (osteoarthritis) and other joint diseases, such as gouty arthritis and rheumatoid arthritis.
The term "geodi", typically European, inconvenient for comparison with mineralogy, where the geode is a small hollow rock bounded by crystals. In fact, the geodes are cystic spaces that are formed in the subchondral bone, or below the articular cartilage; similar to gaps or cavities, on radiological examination the geodes appear as multiple radiolucent areas of various sizes, an expression of
- a more or less marked bone resorption, with the interposition of fibrous tissue
- any accumulation of synovial fluid penetrated by the joint space
These cysts are often multiple, of variable size and pyriform appearance.
Causes of origin
But why do geodes form? It is believed that during the arthrosic process the origin of the bone cysts is linked to the penetration of synovial fluid into the subchondral bone affected by bone fractures which, added to the vascular insufficiency of this area, produce cysts that can communicate secondarily with the joint.
- Genetic predisposition + Articular inconsistency, Overload or Obesity → † Wear and damage of articular cartilage → 'reduction of joint thickness + release of inflammatory mediators → increased turnover of subchondral bone (underlying cartilage) → † osteophyte formation + areas of microfractures with necrosis, bone resorption and subsequent penetration of the synovial fluid, favored by cracks present on the pathological cartilage surface, in correspondence with the areas of greatest load → † 'formation of bone cysts (geodes) which initially communicate with the joint but which later they can close by deposition of fibrous tissue
- narrowing of the joint line
- sclerosis of the subchondral bone
- osteophyte formation in the joint margin
Osteophytes are marginal osteocartilaginous proliferations in the form of a beak or claw, which are formed in an attempt to increase the surfaces of joint contact. Thus, bone cysts can be interpreted as the result of a "saving" of the bone which, in an attempt to have greater resistance in some areas, achieves a major resorption in others.
In the absence of degenerative signs of the bones or of the studied joint, the geodes can be considered benign neoformations, evidenced by the term "aneurysmal bone cyst", whose origin is still uncertain.
Care
To date there is no simple and effective cure for osteoarthritis and related bone and cartilage alterations; once started, cartilage degeneration is almost unstoppable and irreversible, especially when signs of osteophytes and geodes are already evident. Through appropriate therapeutic aids it is however possible to slow down the phenomenon
- anti-inflammatory drugs, topical application of capsicin, infiltration of hyaluronic acid, reduction of body weight in the case of obesity, constant physical activity involving proprioceptive and mobility exercises avoiding excessive overloads, correction of possible postural defects, integration of glucosamine and chondroitin sulfate for orally, alkaline diet rich in omega-three
or proceed with the surgical replacement of the joint damaged by the geodes with a mechanical prosthesis.
