Smith & Nephew's European Trufit Study

The purpose of this clinical study is to demonstrate the effectiveness and safety of the Trufit CB (Cartilage Bone) implant for the treatment of single, isolated cartilage defects of the knee compared to Microfracture.

Up to 315 subjects, ages 18 years and older with a single, isolated cartilage defect of the knee will be randomized in a 1:1:1 ratio to 1 of 3 treatment groups:

* Trufit CB Implant with rehabilitation protocol;
* Trufit CB Implant with rehabilitation protocol;
* Microfracture with rehabilitation protocol

Rehabilitation program may be standard (6 weeks touch weight to full weight bearing) or accelerated (2 weeks touch weight to full weight bearing).

Eligibility Criteria:
Inclusion Criteria:

* Capable of providing informed consent;
* Eighteen (18) years or older and skeletally mature on the date of study enrollment;
* Willing and able to attend all follow up visits and complete all study related procedures and evaluations including, but not limited to adhering to the rehabilitation protocol;
* Single, isolated cartilage defect (ICRS Grade III - IV) in the knee (medial or lateral femoral condyle or trochlea) that is ≥ 1cm2 (10 mm) and ≤ 2cm2 (20 mm) in area and requiring a maximum of 2 implants (if randomized to TRUFIT CB); Note: Lesion size should be assessed as the product of the longest diameter and its perpendicular applied at the widest portion of the lesion.
* Candidate for cartilage repair surgery as a result of a single, isolated symptomatic cartilage lesion;
* Presents with stable health at the time of study enrollment;
* BMI of ≤ 32.

Exclusion Criteria:

* Female of child-bearing potential who is pregnant or plans to become pregnant over the course of the study;
* History of alcohol or drug abuse;
* Presents with patellofemoral instability or other anatomical malalignment in the study knee;
* Any diagnosis that would preclude the patient from successfully completing the study rehabilitation protocols;
* Unable or unwilling to follow post operative procedures (e.g. rehabilitation protocol);
* Received one or more intra-articular steroid injections in the study knee within the previous 3 months;
* Presents with ipsilateral hip disease, as determined by pain or restricted range of motion upon physical examination;
* Treated with either an investigational device or drug within one (1) month of study enrollment, or plans to be treated with an investigational device or drug in the next 24 months;
* Diagnosed rheumatoid arthritis, ankylosing spondylitis (Bechterew syndrome), or calcium pyrophosphate dihydrate disease(chondrocalcinosis);
* History of severe vascular or neurological disease, uncontrolled diabetes, or is immunosuppressed (e.g. HIV positive);
* Musculoskeletal disease, including degenerative bone diseases such as osteochondritis dissecans and osteonecrosis;
* Pathologic conditions of the bone (e.g. osteoporosis, cystic changes, hyperparathyroidism, Paget's Disease, hypercalcemia, prolonged use of steroids);
* Active infection, or evidence thereof, at the lesion site;
* Requires the use of any medication(s) or treatment(s) known to have an effect on bone metabolism (e.g. bisphosphonates, chemotherapeutic or immunosuppressive agents);
* Requires concomitant osteotomy, partial lateral meniscectomy or complete meniscectomy; Note: Concomitant ACL reconstruction or revision, as well as meniscal repair and partial medial meniscectomies are permitted under the study protocol.
* Has undergone an ACL reconstruction, osteotomy, chondral resurfacing procedure or partial meniscectomy (≤ central third of the meniscus) in the last year and has not completed at least 6 months of rehabilitation since such surgery; Note: Patients who have undergone these procedures within the last year and have completed at least 6 months of rehabilitation are eligible to participate in the study.
* Any active, implanted medical device (e.g. cochlear implant) or metallic implant (other then dental work) that may interfere with Magnetic Resonance Imaging (MRI);
* Any condition (e.g. claustrophobia) that may interfere with the patient's ability to undergo MRI;
* Diagnosis requiring placement of an active implant (e.g. cardiac pacemaker, vagus nerve stimulator, etc.) within the next 24 months.