Articular cartilage is a specialized, smooth tissue covering the ends of bones within a joint, allowing them to glide with minimal friction. This thin, resilient layer functions primarily as a shock absorber, distributing mechanical loads across the joint surfaces during movement. Cartilage fissuring represents one of the earliest forms of damage to this protective layer, indicating the beginning of a breakdown process. This initial structural failure compromises the joint’s biomechanical environment, setting the stage for widespread joint deterioration.
Defining Cartilage Fissuring and Grading
Cartilage fissuring describes the formation of vertical cracks or splits within the articular surface. These fissures are partial-thickness defects, meaning they affect the superficial layer of the cartilage without extending through to the underlying bone. This early damage is often difficult to detect on standard imaging, frequently requiring direct visualization during an arthroscopic procedure for accurate assessment.
Medical professionals use standardized systems, such as the Outerbridge classification, to grade the severity of cartilage damage from 0 to IV based on the depth and extent of the lesion. A Grade I lesion is characterized by softening and swelling of the cartilage surface, sometimes called chondromalacia, which precedes crack formation. Grade II is defined by a partial-thickness defect where fissures are present on the surface but do not extend to the subchondral bone.
Primary Factors Leading to Fissuring
Fissuring is typically initiated by a combination of mechanical overload and biological degradation. One major factor is acute, high-impact trauma, such as a sudden fall or a sports injury involving a forceful twist on a bent joint. This type of injury can cause the cartilage to shear or compress excessively, leading to immediate crack formation.
Chronic, repetitive microtrauma also plays a significant role, often manifesting as wear and tear over many years. Activities that place constant, high-magnitude stress on a joint, such as long-distance running or heavy labor, slowly degrade the collagen and proteoglycan network that provides cartilage its strength and elasticity.
Biomechanical misalignment of a joint, such as being bow-legged or knock-kneed, introduces another layer of stress. This misalignment causes uneven load distribution, concentrating force in specific areas. The localized pressure accelerates the breakdown of the cartilage matrix and promotes the formation of fissures. Age-related degenerative changes naturally reduce the cartilage’s resilience, lowering the threshold for mechanical damage.
Common Affected Joints and Progression
Cartilage fissuring most frequently occurs in weight-bearing joints that endure the greatest mechanical stress, particularly the knee, hip, and ankle. The knee is the most common site, especially on the femoral condyles and the back of the kneecap (patella). The shoulder and elbow can also be affected, though less frequently, usually due to direct impact or repetitive overhead motion.
The natural history of cartilage fissuring is potential progression if the underlying cause is not addressed. The initial partial-thickness fissure is a structural weakness that deepens and widens over time as it is exposed to daily forces. The fissured cartilage may begin to fray, developing a shredded or “crab-meat” appearance, which further compromises the smooth joint surface.
If the damage is left unchecked, the fissure can eventually extend completely through the cartilage layer to expose the underlying subchondral bone, classified as Outerbridge Grade IV damage. This full-thickness defect eliminates the protective cushion, leading to bone-on-bone friction. The exposed bone triggers a painful, inflammatory response and is the biological marker for the development of end-stage joint disease, known as osteoarthritis.
Recognizing the Signs and Management Options
The symptoms associated with cartilage fissuring can be subtle and variable. Patients commonly report a dull, persistent joint pain that is exacerbated by weight-bearing activities like walking or climbing stairs. Intermittent swelling, or effusion, is another frequent sign, occurring as the joint lining reacts to shed cartilage fragments and inflammation.
Mechanical symptoms are also characteristic of fissuring. Individuals may experience catching, clicking, or a sensation of the joint giving way when they put weight on it. If a small piece of the fissured cartilage breaks off, it can become a loose body within the joint space, potentially causing temporary locking.
Management generally begins with conservative, non-surgical strategies aimed at reducing symptoms and slowing damage progression. Physical therapy is a primary intervention, focusing on strengthening surrounding muscles to improve stability and reduce mechanical load. Activity modification is also recommended, involving the avoidance of high-impact exercises.
Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to manage pain and reduce inflammation. Injections, such as hyaluronic acid to improve joint lubrication or platelet-rich plasma (PRP) to promote a better biological environment, are sometimes utilized. For more advanced fissuring where conservative measures fail, surgical options may be considered to either smooth the damaged surface (chondroplasty) or stimulate the growth of repair tissue through procedures like microfracture.