Cartilage damage is one of the more sobering diagnoses in orthopedic medicine, not because it is always catastrophic, but because the knee cannot simply repair itself the way other tissues can. A bone fracture heals. A muscle strain resolves. A chondral defect does not follow that same healing pattern, and some cartilage injuries may worsen over time depending on their size, location, severity, and the individual patient.
For patients dealing with knee pain, swelling, or mechanical symptoms like catching or locking, understanding what is actually happening to the cartilage surface matters. It shapes the decisions around treatment, timing, and what the reasonable goals of care actually are.
Our specialists at Skyline Orthopedics evaluate cartilage injuries with an eye toward preserving the joint for as long as possible, using the approach that fits the patient rather than a one-size formula.
What Is a Chondral Defect and Why Cartilage Cannot Heal Itself
Articular cartilage is the smooth, white tissue that covers the ends of bones inside the knee joint. It allows the femur, tibia, and patella to glide against one another with minimal friction and helps distribute load across the joint surface. When that surface is damaged, the result is a chondral defect, essentially a focal area where the cartilage layer is thinned, cracked, or missing entirely.
The reason these injuries are so clinically significant comes down to biology. Articular cartilage is avascular, meaning it has no direct blood supply. Healing in most tissues is driven by blood bringing oxygen, nutrients, and repair cells to the injury site. Because cartilage lacks that pathway, it has a very limited capacity to repair itself on its own.
As orthopedic research consistently shows, when the body does attempt to fill a cartilage defect naturally, it typically produces fibrocartilage rather than the original hyaline cartilage. Fibrocartilage is mechanically inferior. It wears faster, provides less cushioning, and does not replicate the properties of native cartilage. Over time, an untreated or inadequately managed chondral defect can progress to broader joint surface deterioration.
Chondral defects range in severity. Some are superficial and cause intermittent pain with activity. Others involve full-thickness loss down to the underlying bone (osteochondral defects), which are more complex to treat and tend to have a greater impact on daily function. Size matters too. A small, contained defect in a low-load area of the knee behaves very differently from a large lesion on a primary weight-bearing surface.
Osteochondritis Dissecans: A Specific Type of Cartilage Problem
Osteochondritis dissecans (OCD) is a condition in which a localized area of subchondral bone loses its blood supply, leading to changes in the bone and the cartilage sitting above it. Over time, the affected fragment may become unstable and, in some cases, detach from the surrounding joint surface.
OCD most commonly affects the knee, and within the knee, the medial femoral condyle is the site involved in the majority of cases. The condition tends to appear in adolescents and young adults, with higher rates in patients who are active in repetitive loading sports. Repetitive microtrauma is considered a significant contributing factor, though genetic predisposition and other elements may also play a role.
OCD is more prevalent in individuals between the ages of 10 and 20, with a higher incidence in males. Juvenile OCD, occurring in patients whose growth plates have not yet closed, carries a better prognosis for healing with conservative management than OCD in skeletally mature adults.
Symptoms are often non-specific early on. Patients may notice vague activity-related pain, swelling, or stiffness. As the lesion progresses, mechanical symptoms such as catching, clicking, or locking can develop if the fragment becomes unstable. MRI may be recommended when clinically appropriate to provide additional information about the size, location, and stability of the lesion beyond what can be determined through examination and X-rays.
Non-Surgical Approaches Worth Trying First
Not every cartilage injury requires surgery from the outset. For appropriately selected patients, a structured non-operative approach may reduce symptoms and improve function, and in younger patients with stable OCD lesions, it can sometimes allow healing without surgical intervention.
Non-surgical management typically involves several components working together. Activity modification reduces the mechanical stress that aggravates the injury. Physical therapy focuses on building strength in the quadriceps, hamstrings, and hip stabilizers to better distribute load through the joint. Offloading braces may help redirect force away from the affected area. Anti-inflammatory medications can help manage pain and swelling during flares.
For patients with early or stable OCD, a period of protected weight-bearing and reduced activity is often the first line of management. Younger patients with open growth plates frequently respond well to this approach, though it requires consistent follow-through and regular monitoring with imaging to confirm the lesion is responding appropriately.
Injections including corticosteroids or viscosupplementation (hyaluronic acid) are sometimes used to manage symptoms in patients with cartilage damage, though their role is primarily palliative. They can help reduce pain and improve comfort in the near term but do not restore the cartilage surface or address the underlying structural problem.
The physicians at Skyline Orthopedics evaluate each patient individually to determine when conservative management is reasonable and when continuing to delay surgical treatment may allow the injury to progress beyond what less invasive options can address.
Cartilage Restoration Options and How Surgeons Choose Between Them
When non-surgical management has not provided adequate relief, or when the characteristics of the lesion make conservative treatment less likely to provide sufficient improvement, surgery may be considered. Depending on the procedure, cartilage restoration surgery may aim to address the damaged area, improve joint function, reduce symptoms, and support joint preservation.
Several cartilage restoration techniques are available. The right choice depends on factors including defect size, defect depth, lesion location, whether subchondral bone is involved, patient age, activity demands, and what prior treatments have been tried.
Microfracture
Microfracture is a marrow stimulation technique performed arthroscopically. The surgeon uses a small pick or awl to create perforations in the exposed bone beneath the cartilage defect, allowing blood and bone marrow cells to fill the area and form a clot. Over time, that clot matures into fibrocartilage, providing some coverage of the defect.
Microfracture is generally considered for smaller, contained lesions, typically under two square centimeters, in patients who are willing to follow a strict post-operative protocol including a period of non-weight-bearing. It is a relatively low-complexity procedure and can provide meaningful short-term symptom relief. The trade-off is durability. The fibrocartilage formed is not identical to native hyaline cartilage, and results can deteriorate over time, particularly in patients with larger lesions or higher activity demands.
Osteochondral Autograft Transfer (OATS)
OATS, also called mosaicplasty, involves harvesting one or more small cylindrical plugs of healthy cartilage and bone from a lower-load area of the patient’s own knee and transferring them into the defect. Because the graft comes from the patient’s own body, there is no concern about graft rejection, and the transplanted tissue includes genuine hyaline cartilage.
OATS is typically well suited for small to medium defects in younger, active patients. The main limitation is donor site availability. There is only so much healthy cartilage that can be harvested without compromising the area from which it was taken, which caps the defect sizes that OATS can address. For defects that are too large to fill adequately with autograft plugs, an allograft approach becomes more relevant.
Osteochondral Allograft Transplantation
When the defect is too large for OATS or when the patient does not have sufficient donor site tissue, an osteochondral allograft uses cartilage and bone from a cadaver donor, precisely sized and matched to the recipient’s anatomy. The graft replaces the damaged area with actual hyaline cartilage backed by supporting bone, which can be particularly important when significant subchondral bone loss has occurred.
Allograft transplantation is generally reserved for larger lesions and complex cases, including failed prior procedures. It carries longer recovery demands and depends on graft availability and matching, but it offers a structural restoration that other techniques cannot provide at that scale. Published research reports meaningful pain relief and functional improvement in appropriately selected patients, though individual outcomes vary.
How Surgeons Choose Between These Options
There is no universal algorithm. Lesion size is one of the most important factors: smaller defects under roughly two square centimeters are more commonly addressed with microfracture or small autograft plugs, while medium defects may suit OATS well, and larger lesions tend to require allograft. Depth matters too. When bone loss is significant, a technique that restores only the cartilage surface may not address the underlying structural deficit adequately.
Patient age, activity level, and prior surgical history all influence the decision as well. A younger, active patient with a contained medium-sized defect on the femoral condyle is a very different candidate than an older patient with a larger defect and prior failed microfracture. An experienced orthopedic surgeon evaluates the full picture before recommending a specific approach.
The Rehabilitation These Procedures Demand
Cartilage restoration surgery is not a quick fix. The procedures themselves are technically demanding, but the rehabilitation that follows is equally important and significantly longer than most patients anticipate. The restored cartilage surface needs time to mature and integrate, and loading it prematurely can compromise the result.
Following microfracture, patients may need a period of restricted or non-weight-bearing activity based on the location and size of the treated lesion and the surgeon’s rehabilitation protocol. These restrictions are intended to protect the healing area during the early stages of recovery.. Continuous passive motion may be used in the early phase to nourish the forming tissue without stressing it. Gradual reintroduction of weight-bearing follows, with return to full activity typically measured in months rather than weeks.
OATS and allograft procedures follow a similar principle. The graft must integrate with the surrounding bone and cartilage before meaningful load can be applied. Early rehabilitation focuses on maintaining range of motion, controlling swelling, and preserving muscle function without stressing the graft. The subsequent phases build progressively toward functional strength and activity-specific training.
Joint Preservation: The Goal Behind the Treatment
Knee cartilage injury and preservation is not just a surgical concept. It reflects a broader philosophy of care: that intervening appropriately and early enough can protect the joint from the kind of cumulative damage that leads to arthritis and, eventually, the need for replacement.
Significant cartilage defects can alter how forces are distributed across the knee and may contribute to additional joint changes over time. Joint preservation procedures are designed to address focal cartilage damage and improve joint mechanics in appropriately selected patients.
For younger and active patients, preserving the natural knee for as long as reasonably possible may be an important treatment goal. Cartilage restoration procedures may help improve symptoms and function, but their long-term effects vary, and no procedure can guarantee that a future knee replacement will be avoided or delayed for a specific period.
That said, no procedure guarantees a specific outcome, and cartilage restoration does not make the joint immune to future problems. Patients who maintain a healthy weight, continue with appropriate strengthening, and follow up with their physician over time give their knee the best chance of lasting well after the procedure.
Frequently Asked Questions About Knee Cartilage Injury Preservation
Protecting Your Knee for the Long Term
Cartilage injuries deserve appropriate evaluation, particularly when pain, swelling, catching, locking, or activity limitations persist. Because treatment options depend on the size, location, severity, and symptoms associated with the defect, an orthopedic evaluation can help determine whether monitoring, non-surgical care, or a cartilage restoration procedure may be appropriate.
At Skyline Orthopedics, our team evaluates knee cartilage injuries carefully and takes time to explain what the findings mean and what paths forward exist. Whether you are exploring non-surgical management or trying to understand whether a restoration procedure makes sense for your situation, we are here to help you make an informed decision.
Contact us today to schedule an evaluation and get the answers you need.
Written by Dr. Jacob Stelter, MD, FACEP
Dr. Jacob Stelter is a board-certified physician specializing in sports medicine and non-operative orthopedics, treating a wide range of orthopedic and sports-related injuries including concussions, joint injuries, fractures, overuse injuries, and arthritis. He attended Loyola University Chicago Stritch School of Medicine, completed his residency in emergency medicine at Northwestern University, and finished a sports medicine fellowship at the University of Cincinnati. His approach focuses on holistic patient care, combining medical therapies, diagnostic testing, lifestyle and nutrition modifications, and counseling.
