What Is Cartilage Fissuring? Causes, Symptoms & Treatment

Cartilage fissuring is a physical crack or split in the smooth, glassy surface of articular cartilage, the tissue that caps the ends of bones inside a joint. These fissures range from shallow surface cracks barely visible to the naked eye to deep splits that extend all the way down to the underlying bone. The condition sits on a spectrum of cartilage damage that can begin with softening and progress through fragmentation, and it is one of the hallmarks of early joint degeneration. Understanding what drives fissuring, how it announces itself, and what can be done about it matters because untreated cartilage cracks tend to widen over time rather than heal on their own.

How Cartilage Fissures Form

Articular cartilage is built from a dense mesh of collagen fibers woven through a gel-like matrix rich in water-attracting molecules called proteoglycans. When that mesh is intact, the surface is slippery and resilient enough to absorb the compressive forces of walking, running, and jumping. A fissure forms when the collagen network breaks down at a particular spot, allowing the surface to crack open under load.

Two broad forces drive that breakdown. The first is mechanical. A sudden impact, a pivot on a planted foot, or a fall onto a bent knee can generate strain rates high enough to physically split the cartilage surface. Research on impact-induced cartilage failure has found that the speed at which strain builds and the peak shear stress at a given spot are the strongest predictors of where a fissure will open up, more so than the total force applied to the joint as a whole.¹ In practical terms, this means a quick twist under moderate load can be more damaging than a slow, heavy press.

The second force is biochemical. Inflammatory molecules inside the joint stimulate cells to release enzymes that chew through cartilage matrix. Among the most studied are matrix metalloproteinases, a family of enzymes that dismantle collagen and proteoglycans. When inflammation is present, whether from an old injury, chronic overuse, or a systemic condition, these enzymes tip the balance from maintenance to destruction.² The subchondral bone beneath the cartilage can contribute to this cycle too, producing its own inflammatory signals that degrade the cartilage from below.³

Once the proteoglycan barrier in cartilage is compromised, collagen fibers lose their protective shield and become exposed to further enzymatic attack. Laboratory work shows that when proteoglycan-degrading enzymes open the door, collagen-cutting enzymes can reach deeper fibers, accelerating the damage in a cascading fashion.¹ Animal studies confirm that collagen damage tracks closely with the presence of surface fibrillation and is absent in areas where the surface remains intact, reinforcing the idea that fissuring is both a cause and a consequence of matrix breakdown.⁴

The Grading Scale Surgeons Use

When a surgeon looks at cartilage during an arthroscopy or on imaging, they typically classify the damage using a system called the Outerbridge classification, one of the most widely used grading tools for cartilage lesions. It assigns a grade from 0 to 4 based on how far the damage has progressed:⁵

Grade 0: Normal, healthy cartilage with no visible changes.
Grade 1: The cartilage feels soft and looks swollen, but the surface is still intact.
Grade 2: Fragmentation and fissuring are present in a small area, roughly half a centimeter across or less.
Grade 3: Fissuring extends through the cartilage all the way to the underlying bone, and the affected area is larger than half a centimeter.
Grade 4: The cartilage is gone entirely, and raw bone is exposed.

Fissuring, then, first appears at Grade 2 and defines the transition from a surface that is merely softened to one that is structurally cracked. Knowing your grade matters because treatment options shift significantly between lower and higher grades. A Grade 2 lesion may respond to conservative care, while a Grade 4 lesion with exposed bone almost always requires surgical intervention.

Why Fissured Cartilage Hurts When Cartilage Has No Nerves

One of the most counterintuitive things about cartilage damage is that cartilage itself contains no nerve fibers, no blood vessels, and no lymphatic channels.⁶ So how can a crack in something that cannot feel pain cause so much discomfort?

The answer lies in the surrounding tissues. As a fissure deepens, it alters the way mechanical load is distributed across the joint. The subchondral bone sitting directly beneath the cartilage defect absorbs forces it was never designed to handle alone. That bone does have nerve fibers, and changes in its structure, including fluid pressurization and shifts in local acidity driven by bone-remodeling cells, can directly excite those nerves and generate pain.⁷ The synovium, the thin membrane lining the joint capsule, is also richly innervated and becomes inflamed when loose cartilage fragments and inflammatory debris float into the joint fluid.

This disconnect between the location of the damage and the source of the pain explains why two people with identical-looking fissures on an MRI can have wildly different levels of discomfort. The degree of subchondral bone involvement and the amount of synovial inflammation vary from person to person and from joint to joint.

Typical Symptoms

Cartilage fissures do not always produce symptoms right away. A shallow surface crack can exist for months or years without causing noticeable trouble, particularly in a joint that is not under heavy repetitive stress. When symptoms do appear, they tend to develop gradually and include:

Activity-related pain: Aching during or after weight-bearing exercise, stairs, or squatting, with relief at rest.
Swelling: Mild to moderate joint effusion that comes and goes, often worse after a busy day.
Catching or locking: A sensation that something is stuck inside the joint, caused by loose cartilage flaps interfering with smooth motion.
Stiffness: Particularly after sitting or sleeping, improving with gentle movement.
Crepitus: A grinding or crackling sound or sensation when moving the joint through its range.

None of these symptoms are unique to cartilage fissuring. Meniscus tears, ligament sprains, and early arthritis can look and feel similar. That overlap is one reason imaging is important for nailing down the diagnosis.

How Fissures Are Detected

Physical examination can raise suspicion, but cartilage fissures are not something you can reliably diagnose by feel alone. The gold standard for directly seeing a fissure has historically been arthroscopy, a small camera inserted into the joint through a keyhole incision. Increasingly, though, MRI is used as the first-line imaging tool because it is noninvasive and can map cartilage thickness across the entire joint surface.

MRI-based three-dimensional thickness mapping has shown strong ability to detect cartilage defects, with measured defect diameters correlating closely with actual defect sizes. In validation work, there was no significant difference between defect width measured on MRI and actual width. MRI tends to slightly underestimate defect depth, however, which means a fissure that looks modest on a scan may be somewhat deeper in reality.⁸ Clinicians often combine MRI findings with clinical symptoms and mechanical testing during an office visit to build a full picture.

Artificial intelligence tools are beginning to enter this space. A recent systematic review of AI models applied to patellofemoral joint pathology found that diagnostic accuracy ranged from about 74% to 99% depending on the model and the condition being identified.⁹ That wide range reflects how early the technology still is; AI may eventually help catch subtle early fissures that human readers miss, but it is not yet a replacement for an experienced radiologist’s eye.

Who Is Most at Risk

Cartilage fissuring is not limited to one age group or one type of activity. Two main paths lead to it: acute trauma and chronic wear.

On the trauma side, sports injuries, workplace accidents, and falls account for many cases. A systematic review of acute cartilage tears in occupational settings found that people in physically demanding jobs and those with above-normal body weight were at higher risk of sustaining acute cartilage injuries.¹⁰ Military personnel, construction workers, and athletes in cutting sports like soccer and basketball are commonly affected. Prior ligament injuries, particularly ACL tears, dramatically raise the likelihood of subsequent cartilage damage in the same knee because the joint becomes mechanically less stable.

On the chronic side, age-related cartilage thinning, low-grade inflammation, and repetitive loading over decades can produce fissures even without a single memorable injury. Obesity amplifies both pathways: extra body weight increases the mechanical load on every step, and adipose tissue generates systemic inflammatory signals that promote enzymatic cartilage breakdown. Genetics also plays a role, though it is harder to quantify. Some people inherit cartilage that is structurally more vulnerable to breakdown, and family history of osteoarthritis is a recognized risk factor.

Will a Fissure Progress to Osteoarthritis

This is the question that worries most people with a new diagnosis, and the honest answer is: it depends on the size, location, and treatment of the lesion. Cartilage does not regenerate well on its own. The tissue has no blood supply to deliver repair cells, and the resident chondrocytes are locked in place by the very matrix they maintain, making it difficult for them to migrate to a wound site.⁶

A literature review examining untreated focal cartilage defects found that patients with these lesions were more likely to experience progressive cartilage damage over time, though radiographic osteoarthritis (the kind visible on standard X-rays) did not appear within the first two years of follow-up in the studies reviewed.¹¹ Separately, research has linked existing cartilage defects to decreased cartilage volume, increased type II collagen breakdown, and joint space narrowing, all hallmarks of early osteoarthritis.¹²

The timeline matters. A small, stable fissure in a young, active person who adjusts their activity and undergoes targeted rehabilitation may stay contained for years. A large, deep fissure in a joint that is already malaligned or chronically inflamed is more likely to expand. Thinking of fissuring as a warning sign rather than a death sentence for the joint is appropriate, but it is a warning that benefits from a response.

Conservative Treatment

For lower-grade fissures, the first line of treatment is almost always nonsurgical. The goals are straightforward: reduce pain, restore joint motion and muscle strength, and improve function, all without accelerating the cartilage damage.¹³

Structured physical therapy forms the core of conservative management. Strengthening the muscles around the joint, particularly the quadriceps for a knee lesion, helps offload the damaged cartilage by improving how force is distributed across the joint surface. Low-impact exercise such as cycling, swimming, and elliptical training keeps the joint moving without subjecting the fissure to the high peak loads that come with running or jumping. Weight loss, when applicable, reduces the mechanical demand on every step. Anti-inflammatory medications can tame acute flare-ups, and activity modification, such as avoiding deep squats or prolonged kneeling, keeps daily stress within bounds the damaged cartilage can tolerate.

Injection-Based Therapies

When conservative care provides incomplete relief, joint injections are commonly considered as a next step before surgery. Three main types are in regular clinical use.

Corticosteroid injections deliver a potent anti-inflammatory directly into the joint, providing quick pain relief that may last weeks to months. They are most useful for managing acute flare-ups but are not a long-term solution, as repeated injections may have their own negative effects on cartilage health over time.

Hyaluronic acid injections, often called viscosupplementation, aim to restore some of the lubricating and cushioning properties of healthy joint fluid. Evidence suggests these injections may reduce pain in mild osteoarthritis for up to about six months, though cost-effectiveness is a concern that patients should weigh.¹⁴

Platelet-rich plasma (PRP) injections concentrate growth factors from the patient’s own blood and deliver them into the joint. Comparative research has found that PRP showed more prolonged benefit than hyaluronic acid injections for reducing pain and improving function, but outcomes were best in younger patients with mild cartilage degeneration. In older patients with more advanced damage, PRP performed about the same as hyaluronic acid.¹⁵ No current injection therapy has been shown to regenerate lost cartilage or reverse structural damage in joints with substantial bone and cartilage loss.¹⁴

Surgical Options

When fissuring is deep, the defect is large, or nonsurgical care has failed, surgery enters the conversation. Several techniques exist, each suited to different lesion sizes and patient profiles.

Microfracture is the most common first-line surgical approach. The surgeon uses a small awl to punch tiny holes through the exposed bone at the base of the defect, releasing blood and stem cells that form a clot over the lesion. That clot eventually matures into repair tissue. The technique works best for defects on the femoral condyles (the rounded ends of the thighbone). Clinical scores improve significantly by about 18 months after surgery, but studies have documented a deterioration in outcomes between 18 and 36 months, particularly for defects outside the femoral condyles.¹⁶ The repair tissue that forms is fibrocartilage, a tougher but less resilient substitute for the original hyaline cartilage that may wear down over time.¹⁷

Autologous chondrocyte implantation (ACI) takes a different approach. Healthy cartilage cells are harvested from a non-weight-bearing area of the patient’s own joint, grown in a lab to multiply their numbers, and then implanted back into the defect. ACI shows greater durability and lower failure rates than microfracture and is effective for larger lesions. A newer version, membrane-ACI, simplifies the procedure and reduces the risk of cartilage overgrowth compared with the original technique.¹⁸ The tradeoff is that ACI is a two-stage surgery requiring months of rehabilitation, and it is significantly more expensive.

Osteochondral autograft and allograft transplantation represent yet another strategy, moving a plug of healthy cartilage and bone from a donor site (either from the patient’s own joint or from a cadaver donor) into the defect. These are typically reserved for medium-to-large lesions where other methods are not feasible.

Cartilage Fissuring in Children and Teenagers

Cartilage damage is often thought of as an adult problem, but kids and teenagers can develop fissures too, usually after sports injuries or from conditions like osteochondritis dissecans, where a piece of cartilage and underlying bone partially separates. The good news is that younger patients have a greater capacity to regenerate cartilage defects compared with adults. The repair techniques used in adults appear to be safe in this age group, with no increased complication rates reported.¹⁹

That greater regenerative potential does not mean cartilage injuries in young people can be ignored. Untreated cartilage damage in a growing joint may predispose the child to premature osteoarthritis decades later.¹⁹ A particular concern in this population is the subchondral bone, which is still developing and is frequently involved in pediatric cartilage injuries. Surgeons working on young patients must balance the desire to repair the cartilage with caution about disrupting growth plates and immature bone.

Hydrogels and the Future of Cartilage Repair

The fundamental limitation of every current repair technique is that none of them perfectly reproduce the original hyaline cartilage. Microfracture produces fibrocartilage. Even ACI, while closer to hyaline, does not always match the mechanical properties of native tissue. Researchers are working on several fronts to close that gap.

One of the most active areas is tissue engineering using stem cell-loaded hydrogels. These are three-dimensional scaffold materials designed to mimic the natural cartilage matrix while supporting cell attachment, growth, and differentiation into cartilage-producing cells. The hydrogel provides structural support and creates a microenvironment that encourages new cartilage to form in the right shape and with the right mechanical stiffness. The technology is still in preclinical and early clinical stages, but the concept is promising because it addresses both the cellular and structural components of the repair problem simultaneously.

Gene therapy approaches that aim to silence the destructive enzymes responsible for cartilage breakdown are also under investigation, as are injectable biological scaffolds that could be delivered arthroscopically without open surgery. None of these are ready for routine clinical use yet, but the pace of research suggests that the treatment landscape for cartilage fissures will look meaningfully different within the next decade or two. For now, the practical takeaway is that early detection and appropriate management of fissures using existing tools remain the best way to preserve joint function and delay the cascade toward osteoarthritis.