Studying long-term changes in a sub-set of patients who undergo the Subchondroplasty procedure including changes in pain, function, and overall health.

This study is designed as a prospective, consecutive series outcomes study. Patients presenting with knee pain associated with bone marrow lesions that meet the inclusion criteria will be eligible to undergo Subchondroplasty procedure. The subjects will be followed for twenty-four (24) months after surgery via office visits and will be contacted once per year for up to 5 years post-operatively and asked questions regarding their pain and functioning to further understand long-term outcomes.. Seventy (70), a ( minimum of sixty-two (62)) patients who meet the inclusion/exclusion criteria will be enrolled in the study. Up to 5 sites will participate in this study. The study is intended to provide an estimate of one-year and two-year clinical success with minimum bias and with sufficient statistical precision to permit meaningful comparison to commonly accepted two-year clinical success rates for currently available treatment alternatives. An improvement of 10 points on the Knee Injury and Osteoarthritis Outcome Score (KOOS) Pain Subscore on the KOOS Scoring System from baseline to 1-year post-operative is considered minimal perceptible clinical improvement and will be used to define the primary clinical success criterion for this study.

Inclusion Criteria:

• Subject is 40-70 of age and skeletally mature
• Subject BMI is < 40
• Subject has experienced pain in knee for at least 3 months
• BML is confirmed on T2 weighted MR Imaging by presence of white signal
• Subject has single BML of tibia, single BML of femur, or adjoining BML's of tibia & femur
• Baseline KOOS pain subscore is ≤65
• Subject's involved knee alignment is defined radiographically as one of the following: Neutral, ≤ to 7 degrees mechanical varus or < 7.5 degrees mechanical valgus
• Subject's ACL and PCL ligaments are intact
• Subject has failed no more than one operative treatment on treatment knee, and none within 6 months prior to enrollment
• Subject is willing and able to sign a written consent form
• The subject has the mental capacity and the willingness to comply with the specified follow-up evaluations, and can be contacted by telephone by the site personnel.

Exclusion Criteria:

• Surgeon deems subject's pain to be primarily related to an alternate condition such as a baker cyst, synovitis, meniscal pathology, or other
• BML caused by acute trauma
• Subject is not neurologically intact (sensory, motor, and reflex deficit)
• Subject is insulin dependent
• Subject has a history of any invasive malignancy (except non-melanoma skin cancer), unless treated with curative intent and with no clinical signs or symptoms of the malignancy for 5 years
• Subject with primary bone tumor in the knee area
• Subject anticipates having a lower extremity surgery other than the investigational surgery during the course of the study
• Subject has a history of substance abuse
• Subject is currently involved in another study or have received investigational product or treatment within the last 30 days
• Subject is pregnant or planning on becoming pregnant during the study period
• Subject is accepting workers' compensation

Patients with single bone marrow edema of the tibia, single bone marrow lesion of the femur or adjoining bone marrow lesions of the tibia and femur (kissing lesions).