Treatment Algorithm for Full Thickness Chondral Lesions. The natural history of a cartilage lesions is not fully understood, today we still don't know if a focal lesion will automatically progress if untreated, historically the factors that have been taken into consideration are related to the size and depth of the lesions after controlling for weight, activity, alignment, and instability. Clinical studies have suggested that lesions less than one square centimeter usually do not progress and that lesions larger than one square centimeter are at a higher risk of progressing. The goal of therapy should be to maximize the patient's opportunity to return to an active and productive life style. The treatment algorithm presented here is based upon my 10 years of clinical experience in treating chondral lesions.

During the selection process of which technique to use, a demand-matched approach needs to be used. This means selecting a technique which is the best fit for the individual patient. It cannot be emphasized enough that the treatment selection needs to match the expectation level of the patient, rather than using the same technique on all patients. Other factors that need to be considered when selecting a treatment method: the age and gender of the patient, the physical demand, the total cost of the procedure, the ease of application for both patient and surgeon. Will the technique burn any bridges if a secondary procedure is required. What are the risks of the complications and the rehabilitation time for the patients? It critical that this type of analysis be performed for each patient being treated.

If a small lesion .5 to 1 cm2 with unstable edges is causing synovial irritation, a case can be made for a stabilizing chondroplasty using techniques which will cause the least amount of collateral damage to the adjacent cartilage. This center uses either with a mechanical shaver or a radio-frequency wand to smooth out the rough cartilage surface. However, the use of RF on articular cartilage remains to be uncertain, technique sensitive and needs to be used with caution. For cartilage defects over the size of one square centimeter discovered during an arthroscopic must be critically assessed before treating it. What is the probability that this lesion is actually causing mechanical symptoms? Is the lesion located on a weight bearing portion of the knee? What are the potential problems if the lesion progresses in a patient's expected lifetime? If it is determined that a treatment of the cartilage lesion is needed, a debridement or a bone marrow stimulation technique could be used to induce a fibrocartilage repair. This center used a bone marrow stimulation technique for lesions between .5 to 2 cm2. There are different repair methods that can induce a fibrocartilage repair. These techniques are inexpensive to initiate and require minimal equipment to breech the subchondral bone plate and are less invasive. The options for inducing bone marrow stimulation can either be a microfracture, a drilling technique, or an abrasion arthroplasty. The choice selected is up to the surgeon's preference. Although the wear characteristics for fibro cartilage is poor compared to normal cartilage, this repair tissue may be adequate for smaller lesions that are well shouldered with contained edges to protect against high joint forces or if the demands for activity form the patient is low. It has also been shown that the outcomes with bone marrow stimulation decreases over the age of 40, therefore for a high demand patient late forties, a bone marrow stimulation technique may be less reliable. A bone marrow stimulation procedure is a reparative technique and considered safe. For larger lesions that have to withstand higher levels of joint forces on the repair tissue, a fibrocartilage cartilage repair has not been shown to be predictable. Therefore, it is more desirable to select a treatment option that can withstand higher loads.

For lesions between one to three centimeters squared, in a high demand patient, you want to use a technique that will have restorative properties. Using autograft osteochondral plugs that are able to fill the defect would be a viable option. The limiting factor with this technique is the amount of tissue being transferred. It has been shown that the harvest site should not to exceed one to two square centimeters for autograft transfers. (Bobic, Morgan and Carter) Harvesting more than that could lead to donor site morbidity.

For lesions greater than two to three centimeters squared, the current options are typically between autologous chondrocyte implantation or an osteochondral shell allograft. The decision to use either an ACI or an allograft is complex and there is overlapping indications. Both are considered restorative procedures. The patient must be aware of the limited ability of the allograft and the potential risk that can occur with allografts. The FDA and the CDC has recently issued warnings regarding the safety of allografts and have instituted new guideline to follow in procuring the tissue.

The long-term success of fresh osteochondral allograft has been excellent. The long-term outcomes with cryopreserved allograft are is an unknown. With fresh allografts you receive 100% cell viability. With cryopresserved grafts the amount of viable cells ranges anywhere from forty to sixty percent when the surgeon receives the graft. An unanswered question is, this good enough to preserve long-term function of the graft. With an osteochondral allograft you can return to activities within 6-8 months, however high demand activities are not recommended.

With regards to autologous chondrocyte implantation, long-term durability is very encouraging from both a clinical and histological perspective as published. Therefore, for lesions larger than 3cm2, ACI is the treatment of choice for active individual. For the very large lesions, those lesions that are going to be ten to twelve centimeters squared with a significant amount of bone loss or are uncontained in more than two edges; these are situations where an allografts are used.