Inclusion Criteria:
* Patient is ≥18 and ≤ 60 years old at the time of surgery;
* Symptomatic patient presenting with moderate to severe pain in the index knee - unresponsive to conservative treatment (i.e. medication, bracing, physical therapy) and/or previous surgical intervention;
* Radiographically diagnosed, by MRI, or through arthroscopy, to have a cartilage defect on the femoral condyle or patella between ≥ 1 cm2 and ≤ 5 cm2, measured as a rectangle length x width;
* Will be having a marrow stimulation plus ProChondrix CR procedure;
* Has an intact meniscus (maximum of ≤50% resected);
* Have the ability to understand the requirements of the study, to provide written informed consent, and to comply with the study protocol.
Exclusion Criteria:
* Has \> 5° of varus or valgus deformity;
* Bipolar articular cartilage involvement (kissing lesions) of the ipsilateral compartment (i.e. \> than ICRS Grade 2 on the opposing articular surface);
* Associated damage to the underlying subchondral bone \>2 mm requiring osseous repair;
* Requires concomitant ligament repair other than Anterior Cruciate Ligament (ACL) or Medial Patella-Femoral Ligament (MPFL) reconstruction;
* Body Mass Index (BMI)of ≥ 35 kg/m2;
* Active malignancy: undergoing treatment for tumor or boney traumatic injury or a history of any invasive malignancy (except non-melanoma skin cancer), unless the patient has been treated with curative intent and there have been no clinical signs or symptoms of the malignancy for at least 5 years;
* Clinical and/or radiographic disease in the affected joint that includes: osteoarthritis or avascular necrosis, gout or a history of gout or pseudogout, osteochondritis dissecans with significant bone loss;
* Cartilage lesion location such that the implanted graft will not be adequately shouldered;
* Active local microbial infection or a systemic infection, including prior or pending treatment for HIV, syphilis, Hepatitis B or Hepatitis C;
* Currently immunologically suppressed or immunocompromised, or a medical condition requiring radiation, chemotherapy or immunosuppression;
* Unstable cardiovascular, renal, hepatic, endocrine and/or pulmonary disease, cancer or uncontrolled diabetes;
* Has a history of any inflammatory or connective tissue disease, such as, systemic lupus erythematosus (SLE), Addison's disease, Crohn's disease, multiple sclerosis, polychondritis or rheumatoid arthritis;
* Received hyaluronic acid injections into the joint space ≤ 90 days prior to surgery;
* Is a female patient who is pregnant;
* Physically or mentally compromised (i.e. being currently treated for a psychiatric disorder, senile dementia, Alzheimer's disease) in a manner that would compromise his/her ability to participate in the clinical study;
* Has a history of substance abuse (recreational drugs, alcohol) or has been treated in the last 6 months before enrollment for alcohol and/or drug abuse in an in-patient substance abuse program;
* Patients who, in the opinion of the Investigator, would not be able or willing to comply with the protocol;
* Is currently involved in a study of another investigational product for similar purpose or has been in the previous 90 days;
* Has any contraindications for MRI;
* Is a ward of the state, prisoner, or transient.
