ACI of the knee for patients with cartilage injuries

The second surgery is an open procedure. The site of the defect is debrided, and vertical borders are established (see Figure 2). The area is measured and outlined with a surgical marker. A template of the defect size and shape is made using glove paper or other sterile paper. Periosteum is then harvested from the tibia and trimmed to match the exact dimensions of the defect. Other manufactured patches are currently undergoing FDA review and, if approved, would eliminate the need for the harvest of periosteum. The patch is sewn over the defect with fine 6-0 Vicryl suture and then sealed with fibrin glue. When all but one small area of the patch has been sewn, the watertight seal is tested with sterile saline to ensure there are no areas that will allow the new cartilage cells (chondrocytes) to ooze out. Finally, the chondrocytes are injected under the patch (see Figure 3). The sewing of the patch is completed and the skin closed. The area is protected with a hinged knee brace, and the patient undergoes intensive physical therapy to restore normal function.

Articular cartilage lesions are one of many disorders that can cause pain and dysfunction in the knee. Cartilage restoration techniques for focal cartilage defects are becoming increasingly popular, thanks to some of the cutting edge treatments that are available in the United States.

A chondral injury differs from osteoarthritis in several ways. Osteoarthritis is a progressive degenerative disease in which cartilage becomes weak and brittle throughout the joint. Cartilage thins out and wears away, exposing the underlying bone to increased load and friction, causing pain and eventual deformity of the joint. Chondral defects, however, typically occur as the result of an injury and affect a contained area of the cartilage. These lesions are often treated surgically with various techniques, including, but not limited to, chondroplasty (shaving and smoothing the cartilage) and microfracture (drilling tiny holes into the bone to stimulate bleeding, which forms a fibrocartilaginous substance over the lesion). These techniques are not always long-term solutions, however. Much research has gone into newer cartilage restoration techniques to provide better treatments for cartilage defects. ACI is considered an advancement that is able to provide a better, longer-term solution for these difficult cartilage injuries. 

 

Cartilage defects have long-term ramifications if not dealt with properly. Early recognition and appropriate orthopedic referral are important and the primary care provider plays an important role in this process. ACI is not for everyone. Insurance companies largely dictate which patients are eligible for the procedure. Because of its high cost, patients who are at higher risk for failure are less likely to be approved.

The primary care provider is often the first to evaluate an injured patient. During primary assessment, radiographs should always be obtained for a new patient with knee pain, especially one with a recent history of trauma. Standard views are bilateral standing, anteroposterior, lateral, and Merchant views of the knee. These are valuable in ruling out fracture or dislocation and for evaluating the joint for early osteoarthritic changes. Osteoarthritis involves the erosion of articular cartilage and overall breakdown of the joint. Associated radiographic changes include joint space narrowing, subchondral sclerosis, formation of osteophytes, and subchondral cyst formation. A patient with existing osteoarthritis in the knee is not a candidate for ACI because the progressive nature of osteoarthritis deters success. The ultimate treatment for osteoarthritis is a total knee replacement. MRI is not typically indicated for a patient with advanced osteoarthritic changes. However, MRI is the diagnostic standard for evaluation of soft tissue.