Patients presenting with chondral damage report various mechanisms of injury. These mechanisms often include a pivoting or twisting fall, a significant direct impact on the knee, an ACL tear, or a patellar dislocation. The differential diagnosis of any patient presenting with a traumatic hemarthrosis also should include a traumatic chondral lesion. Sometimes, however, the patient remembers no clearly traumatic event and only reports pain with weight bearing.

Patients commonly report the onset of pain localized to one particular compartment or a persistent, dull, aching pain that worsens after activity and may be most noticeable when the patient tries to fall asleep. Loaded activities, such as running, stair climbing, rising from a chair, and squatting, aggravate these symptoms. Sitting for prolonged times, such as in an automobile, a theater, or an airplane, sometimes aggravates pain from a patellar lesion.

In addition to pain, the patient may complain of swelling, crepitus, and giving way, catching, and locking of the knee. These tend to be induced by activity but vary widely from patient to patient.

Joint line tenderness or an effusion sometimes is present depending on the patient’s activity before the evaluation. The alignment of the limb is important to evaluate; this includes looking for varus or valgus alignment, hyperextensile joints, or a flexion contracture.

For patellar or trochlear lesions, subpatellar crepitus, patellar grind, and pull-through sensitivity often are observed. Patellar maltracking, the Q angle, and tightness of the lateral retinaculum should be evaluated. Associated lesions should be considered, along with meniscal signs and joint instability.

In the office, a standard radiographic evaluation should be performed. This includes a standing anteroposterior view of both legs in full extension to look for angular changes and to compare height of the joint space. If this view is not revealing, then a 45-degree flexion, posteroanterior, weight-bearing view to identify subtle joint space narrowing should be obtained. A non–weight-bearing lateral view with 45-degree flexion in which the posterior femoral condyles overlap, an axial view of both patellae to evaluate the patellar alignment, and an anteroposterior, knee-flexion view to outline the femoral intercondylar notch also should be obtained.

Magnetic resonance imaging can help to outline the surface of the articular cartilage and demonstrate localized, full-thickness lesions in a patient with otherwise normal standard radiographs. A layer of fluid or edema surrounding an articular cartilage lesion suggests that it is detached. The two most widely used imaging techniques are the T₁-weighted, fat-suppressed, three-dimensional spoiled gradient echo technique and the T₂-weighted, fast spin-echo technique. Software advances and newer MR imaging techniques with intravenous or intra-articular enhancement are continuing to improve the capability of MR imaging for the evaluation of articular cartilage.

Evaluating articular cartilage lesions is important to facilitate communication, to arrive at a prognosis, and to devise an appropriate treatment plan. An evaluation should consider not only the size and depth of the lesion but also its location, any damage to the subchondral bone, and any associated pathology in the knee, such as an ACL or meniscal tear. The most common classification used for articular cartilage lesions is that of Outerbridge (9). In this system, articular cartilage damage of grade 1 shows softening or blistering of the surface; grade 2 shows fibrillation or superficial fissures of less than 1 cm in diameter; grade 3 shows deeps fissuring extending to the subchondral bone, without exposed bone, and measuring more than 1 cm in diameter; and grade 4 shows exposed subchondral bone (Fig 43.1-2). More recently, the Modified International Cartilage Repair Society Chondral Injury Classification System (10), or ICRS, has been developed. This system is based on the depth and amount of the cartilage injury. Using this system, ICRS grade 1 injuries are superficial, with a soft indentation or superficial fissures and cracks; ICRS grade 2 lesions involve less than half the cartilage depth; ICRS grade 3 lesions involve half or more of the cartilage depth, but not into the subchondral bone; and ICRS grade 4 lesions are osteochondral in extent.

Athletic injuries commonly injure the meniscal cartilage and, sometimes, the ACL as well. Injury to these structures can have a profound effect on the outcome of treatment of articular cartilage lesions. The meniscus cartilage functions to distribute loads more evenly across the joint surface, to improve cartilage nutrition, and to absorb shock. Loss of some or all of a meniscus can lead to osteoarthritis. This relationship makes preservation of the meniscus whenever possible a component of the treatment strategy to reduce articular cartilage injury. Continued ligamentous instability in the knee leads to additional articular and meniscal damage. When instability coexists with articular cartilage damage, the knee should be stabilized at the same time as the articular cartilage is repaired; otherwise, additional damage will compromise any articular cartilage procedure.

Any significant angular change in the leg (valgus or varus alignment) also should be corrected in conjunction with
articular cartilage surgery. If the malalignment is not corrected, then the articular cartilage will be subjected to increased pressures, and the result of the surgery will be compromised.

Treatment algorithms depend on many factors, but size and depth of the associated lesions are paramount. In addition, if a mobile fragment is associated with the lesion, then the possibility for reattachment exists only if the subchondral bone is viable. Some Outerbridge Type 4 lesions have associated bone loss. If the depth of loss is greater than 8 mm, then marrow-stimulating techniques and ACI are not suitable choices, and bone grafting to fill the defect should be performed either as part of an autograft or allograft procedure or as an independent initial step before ACI. Table 43.1-1 outlines the treatment options based upon these factors.

At surgery, it is not uncommon to find a small area of Outerbridge Type 1 or Type 2 injury on a femoral condyle or tibial plateau that does not require any intervention. Small Type 3 lesions that are asymptomatic, especially in athletes participating in low-impact activities, can be observed and treated nonoperatively. Some painful Type 3 lesions may become asymptomatic once the acute synovitis resolves (11,12,13). A linear Type 3 lesion on the femoral condyle or tibial plateau (Fig 43.1-3) should be documented and the patient informed. Specific intervention should await the development of symptoms, particularly in a patient with another, more obvious reason for knee symptoms (e.g., torn meniscus or loose body). Long-term studies suggest that isolated chondral lesions of less than 1 cm in diameter have an excellent or good result without specific treatment and may be left alone (14). As long as these areas do not cause symptoms, intervention should be postponed.

Areas of what could be Outerbridge Type 3 damage observed at MR imaging also warrant a trial of nonoperative care. This includes a course of nonsteroidal anti-inflammatory drugs, physical therapy, activity modification, and possibly, bracing. Evaluating the particular position the athlete plays may provide opportunities for continued participation while “resting” the joint. Changes in the exercise program or technique also may prove to be helpful. Sometimes, the clinical symptoms amount to an overuse syndrome that a period of rest will resolve and are unrelated to small or superficial chondral abnormalities. Bracing options include patellar stabilizing braces for patellofemoral instability and load-shifting braces for angular unicompartmental damage that has not responded to surgical intervention and activity modification.

Other available medications include intra-articular injections of hyaluronic acid (15,16). On occasion, an intra-articular injection of steroid can be helpful. At this point, no conclusive evidence indicates that nutritional supplements are beneficial for the anagement of partial- or full-thickness chondral lesions.

Nonoperative treatment for an athlete often is chosen because of the particular sport’s season. Operating on a player in the middle of his or her season can be a difficult choice, and surgery often is delayed until the season is over. This may be less than ideal. The future impact of this choice
may be profound to the athlete, however, and the decision should be made only after a candid and comprehensive discussion of the injury, its prognosis, and the potential consequences of the various treatment options by the physician with the athlete and, when appropriate, the athlete’s family.

The indications for surgical intervention include symptomatic Outerbridge Type 3 lesions that have failed an appropriate nonoperative trial, Type 4 areas, and damage associated with loose fragments. The goal of this surgery is to relieve the symptoms of pain, swelling, and catching, locking, and giving way as well as to stabilize the articular cartilage to prevent further deterioration and to remove unstable, loose fragments. Some lesions, such as unstable osteochondritis dissecans fragments with viable subchondral bone or fresh traumatic fragments with viable bone, can be treated by primary repair (i.e., refixation to the bone bed). Larger articular cartilage lesions (diameter, >2 cm), especially those with loose fragments, deserve immediate intervention, because the chances of successful nonoperative treatment are low but, if this condition is allowed to go untreated, the risks of more damage are high.

Debridement of Outerbridge Type 3 and Type 4 lesions as a primary treatment is appropriate for smaller lesions, low-demand patients, and incidentally observed lesions with few symptoms (Fig 43.1-4). The best results seem to be in younger patients with symptoms of less than 1 year in duration, a specific history of trauma, no previous surgery, little to no malalignment, and a low body mass index (17). Debridement
should only remove unstable chondral fragments that may cause mechanical symptoms and that are likely to become detached with additional activity or trauma. One study reported good to excellent results in 23 consecutive soccer players treated for partial- and full-thickness chondral flaps by arthroscopic debridement with a 1-year follow-up (18). Mechanical debridement does not stimulate articular cartilage repair (19), and there is a risk that the adjacent hyaline cartilage can be damaged (19,20). With additional trauma, these other areas can proceed to osteoarthritis (21).