An osteochondral defect is a specific injury that involves simultaneous damage to two distinct, interconnected tissues within a joint: the articular cartilage and the underlying subchondral bone. This type of injury is particularly challenging because the articular cartilage has a very limited ability to heal itself. When this protective layer and its bony support are damaged, it disrupts the joint’s mechanics and can lead to pain and long-term dysfunction.
Anatomy, Causes, and Symptoms
The affected anatomy includes the smooth, white hyaline cartilage and the bony layer immediately beneath it, known as the subchondral bone. Hyaline cartilage provides a slick, shock-absorbing surface for smooth joint motion. The subchondral bone provides structural support and essential nourishment to the cartilage layer. A defect creates a focal area where this crucial interface is broken, often exposing the raw bone beneath the cartilage.
Damage generally falls into two categories: acute trauma and repetitive stress. Acute, high-impact injuries, such as a severe fall or a sports-related twist, can directly shear off a segment of cartilage and bone. Repetitive microtrauma from high-impact activities or long-term mechanical stress contributes to the gradual development of a defect. A non-traumatic cause is Osteochondritis Dissecans (OCD), where a piece of bone and its overlying cartilage separate from the surrounding bone, often due to disrupted blood supply.
Patients with an osteochondral defect typically experience persistent or intermittent joint pain that worsens with activity or weight-bearing. Swelling is a common symptom, especially following physical exertion, and the joint may feel stiff or have a reduced range of motion. A clear sign of a mechanical issue is a sensation of the joint catching, clicking, or locking, which can occur if a fragment of the damaged cartilage or bone becomes loose within the joint space. The affected joint may also feel unstable or prone to giving way during movement.
Confirming the Diagnosis
Diagnosis begins with a physical examination to assess the joint’s stability, range of motion, and tenderness. While this assessment raises suspicion, imaging is necessary to precisely locate and characterize the damage. Conventional X-rays are often the first tool used and are useful for visualizing the bony component of the defect, such as a fracture or a loose piece of bone.
X-rays are not sensitive enough to fully evaluate soft tissue damage. Magnetic Resonance Imaging (MRI) is considered the standard imaging modality because it provides detailed visualization of the cartilage, the underlying bone, and the surrounding soft tissues. MRI determines the size, depth, and stability of the lesion, revealing features like bone marrow edema, which are not visible on X-ray. This detailed characterization of the lesion is important for guiding the most appropriate treatment plan.
Non-Surgical and Surgical Treatment Options
Treatment selection depends on the defect’s size and location, the patient’s age, and their activity level. Non-surgical management is the first approach for small, stable lesions or for young patients whose bones are still developing. This conservative treatment involves activity modification, rest, and temporary non-weight-bearing on the affected limb to reduce joint stress.
Physical therapy is a component of non-surgical care, focusing on low-impact range-of-motion exercises and strengthening the muscles surrounding the joint. Medications like non-steroidal anti-inflammatory drugs (NSAIDs) may be used to manage pain and swelling. If non-surgical methods fail to resolve symptoms or if the defect is large or unstable, surgery is typically required.
Microfracture is a common arthroscopic procedure where small holes are created in the subchondral bone. This allows blood and bone marrow elements to seep into the defect, stimulating the formation of fibrocartilage. Fibrocartilage is functional but less durable than original hyaline cartilage. Microfracture is generally reserved for smaller lesions, typically less than two to four square centimeters.
Osteochondral Autograft Transfer System (OATS)
OATS, also known as mosaicplasty, is a single-stage procedure used for larger defects or when a more durable repair is desired. Cylindrical plugs of healthy bone and cartilage are harvested from a non-weight-bearing area of the joint. These plugs are then transplanted into the prepared defect site, providing immediate coverage with native hyaline cartilage.
Autologous Chondrocyte Implantation (ACI)
ACI is a two-stage procedure where healthy cartilage cells are first harvested and cultured in a lab for several weeks. The cultured cells are then implanted into the defect, often with a scaffold, to promote the growth of hyaline-like repair tissue.
Rehabilitation and Long-Term Joint Health
The success of surgical intervention relies on a structured, lengthy post-operative rehabilitation program. Physical therapy begins immediately after surgery, focusing on controlling pain and swelling while protecting the repair site. Early, controlled range-of-motion exercises are introduced to prevent joint stiffness and stimulate the healing cartilage.
Weight-bearing restrictions are enforced for an extended period, often involving crutches for several weeks to months, depending on the procedure and defect size. Full recovery, especially after complex grafting procedures, can take up to a year, with a gradual progression of strength training. Long-term joint health requires lifestyle modifications, including maintaining a healthy weight and favoring low-impact exercise to minimize stress on the repaired surface.