Subchondroplasty® Knee RCT

This is a multicenter, prospective, single-blinded, two-arm, randomized study. Enrolled
subjects will have a single Bone Marrow Lesion of the tibia, single BML of the femur, or
adjoining Bone Marrow Lesions of tibia and femur. Subjects will also be surgical candidates
for knee arthroscopy due to mechanical symptoms, meniscus tear, loose body and/or synovitis.

A stratified blocked randomization will be used to assign subjects to either Subchondroplasty
with arthroscopy or to arthroscopy alone in a 2:1 ratio. Individual sets of blocks will be
determined within study site and lesion polarity status (unipolar vs. bipolar).

Subjects will be enrolled within 60 days prior to surgery and take part in follow-up visits
for two years following surgery. A preoperative visit will occur at the time of enrollment.
Follow-up visits will occur at the study site at 6 weeks, 3 months, 6 months, 12 months, and
24 months post-surgery. Telephone follow-up interviews will be done at 18 months
post-surgery. Target enrollment is 201subjects, to include 134 subjects in the treatment
group (Subchondroplasty + Arthroscopy) and 67 subjects in the control group (Arthroscopy
alone). Subjects will complete the study at the 24 month follow-up visit. For the purposes of
this protocol, a revision will be defined as any partial or total joint arthroplasty or any
bone fixation, bone grafting or bone substitute procedure in the same compartment in the
study knee.

Inclusion Criteria:

- Candidates must meet ALL of the following:

1. Voluntary signature of the Institutional Review Board approved Informed Consent,

2. Male or female subjects between the ages of 30 to 75 years,

3. Body Mass Index < 40 (BMI=kg/m2),

4. Has experienced pain in study knee for at least 3 months,

5. Kellgren-Lawrence grade 1-3 Osteoarthritis in the study knee,

6. BML is confirmed on T2 weighted or Proton Density MR Imaging by presence of white
signal,

7. Single BML of tibia, single BML of femur, or adjoining BML's of tibia & femur
extending to the articular surface of the joint,

8. Surgical candidate for knee arthroscopy due to mechanical symptoms, meniscus
tear, loose body and/or synovitis,

9. Must record a response, at the preoperative study visit, of moderate to extreme
pain for any one of the KOOS Pain Scale questions, P2 through P9,

10. Index knee alignment is defined radiographically as one of the following:
Neutral, ≤ 6° mechanical varus, or ≤ 6° mechanical valgus,

11. Ligaments in the study knee are stable,

12. The contralateral (non-study) knee is stable and functional,

13. Is refractory to conservative non-surgical management

1. having failed 2 or more of the following: hyaluronic acid injection,
corticosteroid injection, NSAIDs, physical therapy, bracing, activity
modification, or minimal surgical intervention (e.g., arthroscopy,
debridement/chondroplasty, and/or loose body removal)

2. and is ≥ 3 months from the start of treatment,

14. Must be physically and mentally willing and able, in the Investigator's opinion
at the time of enrollment, to be compliant with the protocol - including all
follow-up visits, survey completion, weight-bearing restrictions, and
post-operative rehabilitation.

Exclusion Criteria:

- Candidates will be excluded if they meet ANY of the following:

1. BML caused by acute trauma less than 3 months prior to enrollment,

2. Clinical and/or radiographic disease diagnosis of the index knee that includes
any of the following:

1. Kellgren-Lawrence Grade 4 Osteoarthritis,

2. Rheumatoid arthritis, or history of septic or reactive arthritis,

3. Gout or a history of gout or pseudogout in the affected knee,

4. Has more than two clinically relevant BMLs in the index knee,

5. Osteochondritis dissecans of the knee with significant bone loss,

6. Collapse of subchondral bone,

7. BML located at ACL/PCL insertion,

8. MRI evidence of frank ligament instability,

3. Passive knee flexion < 110° or flexion contracture >30°,

4. History of secondary arthropathies (i.e., sickle cell disease, hemochromatosis,
or autoimmune disease),

5. Has a neuromuscular, neurosensory, or musculoskeletal deficiency that limits the
ability to perform objective functional assessment of either knee,

6. If diabetic, blood glucose over 200 mg/dL at time of enrollment,

7. Current smoker or < 3months from smoking cessation,

8. Presents a high surgical risk due to unstable cardiac and/or pulmonary disease,

9. Has HIV or other immunodeficient state including subjects on immunosuppressant
therapies, or has significant illness (metastasis of any type) that decreases the
probability of survival to the 2 year endpoint,

10. Is at substantial risk for the need of organ transplantation, such as renal
insufficiency,

11. Is pregnant or breast-feeding at the time of surgery,

12. 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,

13. Has primary bone tumor in the knee area,

14. Anticipates having a lower extremity surgery other than the investigational
surgery during the course of the study,

15. Is participating concurrently in another clinical trial, or has participated in a
clinical trial within 30 days of surgery,

16. Is receiving prescription pain medication other than NSAIDs or acetaminophen for
conditions unrelated to the index knee condition, chronic use of anticoagulants,
or taking corticosteroids,

17. Active joint infection or history of chronic joint infection at the surgical
site,

18. Prior total meniscectomy of index knee,

19. Has primarily patellofemoral symptoms,

20. Is indicated for concomitant procedures (i.e., microfracture, subchondral
drilling, cartilage allograft, ligament or tendon repair, distal
realignment/osteotomy) in the index knee, with the exception of incidental loose
body removal, debridement, synovectomy, osteophyte removal in locations other
than adjacent to BMLs, and/or partial meniscectomy,

21. Has contraindications for Magnetic Resonance Imaging (MRI),

22. Is receiving worker's compensation or is currently involved in litigation
relating to the index knee,

23. Has a history of substance abuse.