The primary purpose of this investigation is to report the short-term clinical outcomes (2-3 years) of patellofemoral arthroplasty implanted using the MAKOplasty knee resurfacing system.

The primary purpose of this investigation is to report the short-term clinical outcomes of patellofemoral arthroplasty implanted using the MAKOplasty knee resurfacing system.

The secondary purpose is to compare the short-term outcomes, complication rates, and survival rates of this operation to those of our historical controls of patients who underwent either osteochondral autograft transfer or autologous chondrocyte implantation for full-thickness patellofemoral articular cartilage lesions. The investigators believe these data will provide strong evidence to improve the selection criteria for patellofemoral arthroplasty.

All patients will complete validated questionnaires from the Cincinnati Knee Rating System, including the Sports Activity and Function Form, the Occupational Rating Form, and the Symptom Rating Form. Patients will also complete the SF-12 general health questionnaire. In addition to the above mentioned rating systems, patients will also complete questionnaires on post-surgical expectations and general fitness level.

Inclusion Criteria:

• Arthroscopically demonstrated localized and isolated full-thickness articular cartilage lesions (Grade 2B or 3A-B as defined by Noyes & Stabler9) on the patellofemoral joint.
• Lesion is symptomatic as defined by pain, swelling, locking, or catching that affects daily activities.
• Patient provides informed consent.
• Patient agrees to comply with postoperative rehabilitation program.

Exclusion Criteria:

• Obesity (body mass index greater than 35).
• Arthroscopically demonstrated full-thickness articular cartilage lesions (Grade 2B or 3A-B) in the other compartments of the knee.
• Uncorrected varus or valgus malalignment
• Uncorrected knee joint instability
• Knee arthrofibrosis
• Patient unwilling to comply with postoperative rehabilitation
• Significant muscular atrophy and weakness that does not respond to rehabilitation
• History of alcohol or drug abuse within 3 years of the operation.
• Disabling or widespread osteoarthritis or other joint disease in any other joint.
• Presence of a significant connective tissue disease, autoimmune disease, HIV-positive, or immune deficiency syndrome.
• Any contraindications to surgery or other medical disorder that in the opinion of the principal investigator would interfere with the conduct of the study.

The population will include 60 patients (men and women) who undergo patellofemoral arthroplasty by one surgeon.