An osteochondral defect is an injury affecting a joint, involving damage to both the slick articular cartilage covering the ends of bones and the subchondral bone layer just beneath it. These injuries are essentially localized potholes on the otherwise smooth surface of a joint, disrupting its normal function. While they can occur in various joints, they are most frequently found in the knee and ankle.
Common Causes and Symptoms
An osteochondral defect develops from either a single, traumatic event or from the accumulation of smaller stresses over time. An acute injury, such as a direct impact to the joint, a sharp twist, or a fall, can fracture the bone and cartilage. These are common in sports that place sudden, high-impact forces on joints like the knee or ankle.
Repetitive microtrauma is another cause, where overuse from activities like running and jumping gradually wears down a specific area of the joint surface. This stress can lead to the breakdown of the cartilage and underlying bone. In some younger individuals, osteochondritis dissecans is the underlying cause, where a segment of bone and cartilage loses its blood supply and separates from the surrounding tissue.
Individuals with an osteochondral defect often experience a deep, persistent pain that intensifies with weight-bearing activities. Swelling of the affected joint is also frequent, especially following physical exertion. Many people report mechanical symptoms such as a clicking, catching, or locking sensation, and a feeling of instability, as if the joint might buckle.
The Diagnostic Process
Diagnosing an osteochondral defect begins with a clinical evaluation. A physician will discuss the patient’s history of symptoms and any preceding injuries, followed by a physical examination. The doctor assesses the joint’s range of motion, tests its stability, and pinpoints specific areas of tenderness.
Imaging studies are a standard part of the diagnostic process. An X-ray is often performed first to get a clear view of the bone structure, though it may not reveal damage limited to the cartilage. Because of this, a magnetic resonance imaging (MRI) scan is frequently ordered.
An MRI is the most reliable imaging tool for these defects because it provides highly detailed images of both soft tissues and bone. This allows the physician to see the precise location, size, and severity of the damage, which helps guide the selection of the most appropriate treatment plan.
Non-Surgical Treatments
For smaller, stable defects, particularly in younger patients, a non-surgical approach is often the first line of treatment. The goal of this conservative management is to reduce stress on the joint and allow the body’s natural healing processes to function. This approach is typically for defects not causing severe mechanical symptoms.
Treatment begins with rest and activity modification to prevent further irritation of the damaged area. This involves avoiding high-impact activities like running and jumping. To further protect the joint, immobilization using a brace, walking boot, or crutches may be recommended to offload weight from the limb.
Physical therapy plays a supportive role in this strategy. A therapist guides the patient through exercises to maintain the joint’s range of motion and strengthen the surrounding muscles. This helps provide better support for the joint without putting direct pressure on the defect. Nonsteroidal anti-inflammatory drugs (NSAIDs) may also be used to alleviate pain and swelling.
Surgical Interventions
When conservative treatments are not effective, or for defects that are larger, unstable, or present in adults, surgical intervention is often considered. The objective of surgery is to restore a smooth and functional joint surface to alleviate pain and help prevent the long-term development of arthritis. The specific procedure chosen depends on factors like the size and location of the defect.
One surgical option is debridement, also known as chondroplasty. In this arthroscopic procedure, the surgeon trims away and smooths out damaged, unstable flaps of cartilage. This can reduce symptoms like catching and locking, though it does not repair the underlying defect.
Another technique is marrow stimulation, with microfracture being a common example. The surgeon creates small holes in the bone at the base of the defect to trigger a healing response. This allows blood and marrow cells to enter the area, forming a clot that matures into fibrocartilage, a type of scar cartilage that can cover the defect.
For larger defects, cartilage and bone grafting may be necessary. In an osteochondral autograft transfer system (OATS), plugs of healthy tissue are harvested from a non-weight-bearing area of the patient’s own joint and transplanted into the defect. If the defect is too large for an autograft, an osteochondral allograft uses matched tissue from a deceased donor.
A more advanced, two-stage procedure is autologous chondrocyte implantation (ACI). First, a small sample of healthy cartilage cells is arthroscopically removed and multiplied in a laboratory. In the second surgery, the newly grown cells are implanted into the defect, where they can mature into new, durable cartilage tissue.