Patient Evaluation, Cartilage Defect, and Evidence: Putting It All Together

The History

To have a successful relationship with a patient, the desires, needs, and expectations of the patient must be balanced with what is possible. The surgeon must use his best judgment and draw upon the best available evidence, his own experience, and skills to match these goals. This is sometimes not possible and the patient should be referred to someone expert in the condition. Patients often present with pain and limitation of function. They are often anxious and have different reasons for the appointment. Determining the pathology and considering surgical options may not necessarily be what the patient is seeking.

• An opening question such as “What is your goal by coming to see me today?” usually helps to direct the surgeon’s line of questioning and treatment options offered to the patient. The patient may respond;

• “I have knee pain and I want to know what it is and if it can be treated with physical therapy”

• “I have knee pain and a family history of osteoarthritis and I wanted to avoid knee replacement surgery”

• “I have been referred to Dr. X for a specific knee reconstructive procedure”

• “I have no pain, but I was sent here because I have a cartilage defect.”

Alternatively, the patient may be self-referred based on his own ambitions. This is becoming more commonplace in the day of the World Wide Web. This is especially true in the modern age of the Internet where patients are often well-informed and wish to take matters into their own hands: “empowerment of the patient”. The cartoon ( Fig. 4.1 ) illustrates this. A useful tool in developing a healthy relationship with the patient are the 5 Es ( Fig. 4.2 ).

Cartilage repair and joint preservation are relatively new topics in the orthopedic management of young patients without large cohorts of patients having been treated or long-term follow-up. Internet information is not always reliable, is not peer-reviewed, may be market-driven, and it is therefore up to the orthopedic surgeon to know the evidence as it exists and present this to the patient as an educator, patient advocate, and doctor.

Patient Characteristics

The surgeon’s recommendation of treatment options may very well depend on patient characteristics. A patient who has a high sense of vitality and optimistic outlook with strong social supports has demonstrated a good clinical outcome with almost any surgical procedure. We have reviewed our clinical outcome data using the Short Form 36 questionnaire and had noted that vitality and social supports played strongly into a positive clinical outcome with physical pain relief and well-being (paper presented at the International Cartilage Repair Society 2002). I have also found that patients who are athletic at baseline and had a relatively acute injury less than 1 year before, do better clinically after surgery. It is suspected that if the athlete becomes deconditioned, the injury becomes chronic with thickened subchondral bone and expanding margins such that both the patient and the lesion require more extensive rehabilitation. Obesity is also a factor that faces us as surgeons. It is approaching epidemic proportions in the United States with approximately 30% of the population being considered obese. It has been demonstrated in the osteotomy literature that body weight greater than 1.32 times normal adversely affects the outcome and survivorship of osteotomy surgery. Obesity has also been shown to correlate with an increased incidence of osteoarthritis, which presumably corresponds to enlargement of an existing cartilage defect, or factors adversely towards a cartilage repair procedure because of the force across the regenerative tissue. Counseling about weight loss prior to a biologic repair procedure may actually prevent the need for the procedure based on symptom relief with weight loss. For the morbidly obese patient with a BMI greater than 40 or Class III obesity, gastric bypass surgery may be necessary. Some insurance carriers in the United States will not allow cartilage repair in patients with a BMI greater than 30; for other carriers, the cutoff is a BMI of 35. Further research into the correlation between weight and progression of cartilage damage is necessary.

However, patients who are on medications for depression or anxiety or have addictive baseline behavior patterns such as the use of alcohol, smoking, narcotic usage for pain outside the postoperative setting, tend to demonstrate difficult postoperative patient management patterns. These factors must be delineated preoperatively and addressed individually. When discussing with patients who have depression or anxiety, preoperative counseling and maximizing medications to improve postoperative sense of well-being and compliance are important. I do not operate on patients who are taking narcotics for baseline pain management for their chondral defect or osteoarthritis until they are weaned off to a minimum baseline amount of narcotics that will allow good postoperative pain management. Smoking has demonstrated an adverse event with regard to bone healing and spinal fusions, long bone fractures and trauma, and also with the proteoglycan formation during cartilage healing. For this reason we do not offer biologic repair to smokers until they have completed a smoking cessation program. If they are unwilling or unable to follow the program and if they are at the transition age for a prosthetic reconstruction, a unicompartmental, bicompartmental, or total knee arthroplasty is recommended.

Critical Cartilage Defect Size

Cartilage defects may be present and minimally symptomatic if either the defect is small or the activity level is insufficient to cause progression of disease. Previous studies will have identified lesions that are 2 cm ² to coexist without degenerative changes in the knee up to 4 years after onset of symptoms. More recent studies have shown that there were no differences in clinical outcomes in ACL injured and stabilized knees with chondral defects of 2.1 cm ² at 15 years compared with controls in 36 knees. This also supports the finding that lesions less than 2 cm ² are unlikely to progress and this may represent a critical defect size. Based on these studies, early algorithms identified 2 cm ² as a small defect.

A critical size defect is considered a defect that shoulders the subchondral bone well from stimulus, hence reducing symptoms from subchondral bone nerve stimulation and lessening the abrasive effects of the subchondral bone on the opposing articular cartilage and therefore preventing bipolar changes from developing. However, a larger defect that is poorly shouldered will damage the opposing articular surface, developing progressive joint space cartilage loss, remaining symptomatic, and enlarging quickly based on the excessive force on the edges of the defect. Fig. 4.3 demonstrates this principle, which I described in an earlier publication.

A relatively small defect that is symptomatic may be treated by either arthroscopic debridement of unstable margins and left alone or stabilized with a repair tissue that is fibrocartilaginous or hyaline cartilage. However, a larger poorly shouldered chondral defect will require a repair tissue with the same or nearly the same viscoelastic and mechanical properties as normal hyaline cartilage ( Fig. 4.4 ). Procedures that may produce hyaline-like cartilage for this situation will be the topic of the remainder of this chapter ( Fig. 4.5 ).

Prevalence of Articular Cartilage Injury

In making a recommendation to the patient, it is important to recognize defects that are causing symptoms.

Damage to the articular cartilage comprises a spectrum of disease entities ranging from single, focal chondral defects to more advanced degenerative disease. Focal chondral defects result from various etiologies. Patients are approximately evenly split in reporting a traumatic versus an insidious onset of symptoms; athletic activities are the most common inciting event associated with the diagnosis of a chondral lesion. Traumatic events and developmental etiologies such as osteochondritis dissecans (OCD) predominate in younger age groups. Several large studies have found high-grade chondral lesions ( Fig. 4.6 ; Outerbridge grade III and IV) in 5% to 11% of younger patients (less than 40 years) and up to 60% of older patients. The most common locations for these defects are the medial femoral condyle (up to 32%) and the patella, and most are detected incidentally during meniscectomy or anterior cruciate ligament reconstruction. Many of these defects are incidental in nature and asymptomatic.