Enrollment of 500 subjects was met and Sponsor decided to discontinue enrollment as of July 2018. Sponsor believes enrollment number will provide us with sufficient follow-up to submit a substantial manuscript with minimum of 2 year follow-up data.

Post Market clinical outcomes study to collect data on the short - and long-term outcomes for subjects who are undergoing or who have undergone the Subchondroplasty (SCP) Procedure in the knee in a standard clinical setting. Outcomes to be assessed include pain medication usage, pain, function, activity levels and patient satisfaction.

This is a post-market, multi-center, patient outcomes centered study to evaluate the on-label use of AccuFill during the Subchondroplasty procedure. Enrolled subjects will sign an informed consent form, satisfy the inclusion/exclusion criteria and have at least one Bone Marrow Lesion (BML) in the knee. Demographics, medical history and medications will recorded at the time of enrollment. Surgical details including the SCP procedure, concomitant surgical procedures and intraoperative safety events will be recorded. Subjects will complete patient reported outcomes measures pre-operatively including the Visual Analog Scale (VAS) for knee pain, International Knee Documentation Committee Subject Knee (IKDC) Form and the Veterans Rand 12 (VR-12) Item Health Survey. These measures will also be administered post-operatively at 6 weeks, 3 months, 6 months, 1 year, 2 years, 3 years, 4 years, and 5 years. Screening for adverse events and revision surgeries will occur throughout the study.

Target enrollment is 1000 subjects at up to 30 clinical sites. Subjects will complete the study at 5 years or will be withdrawn if the patient undergoes revision surgery of the Subchondroplasty site.

Inclusion Criteria:

1. Surgeon considers patient appropriate for SCP procedure.
2. Patient has agreed to undergo the SCP procedure or has already undergone the procedure.
3. Subject is willing and able to sign a written consent form.
4. The subject has the mental capacity and the willingness to contribute follow-up outcome data.
5. Patient is willing and able to complete outcome forms in person or by phone, email or regular mail.

Exclusion Criteria:

1. Patient is not comfortable with speaking, reading, and understanding questions and providing responses in an available language for the PROs in the protocol.

The SCP Observational Cohort Study will enroll either patients undergoing SCP or patients who have already had the SCP procedure for the treatment of BMLs where bone void filler is placed at the site of the BML (defect).

Surgery, 6 weeks, 3 months, 6 months, 1 year, 2 years, 3 years, 4 years, 5 years

Follow-up compliance: Fewer than half of enrolled participants completed follow-up at or beyond 2 years.