Prospective Evaluation of Clinical Outcomes of the Subchondroplasty® Procedure for Treatment of Symptomatic Bone Marrow Lesions of the Knee.

Introduction: Bone Marrow Lesions (BMLs) have a strong correlation to patient reported pain, functional limitations, joint deterioration, and rapid progression to total knee arthroplasty. The Subchondroplasty® (SCP) Procedure uses AccuFill®, a calcium phosphate bone substitute material (BSM), to treat bone defects such as microtrabecular fractures and BML.

Methods: This observational, prospective, multicenter, cohort study evaluated the effect of the SCP Procedure at two-year follow-up for 70 patients with knee BML. Under arthroscopic and fluoroscopic guidance, the BML was injected with AccuFill®. Patient reported outcomes, including Visual Analog Scale (VAS) pain, Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and modified Knee Society Score (mKSS) were collected through 24 months postoperatively. Radiographs and magnetic resonance images (MRI) were performed at baseline and up to 24 months post-operatively. Patient selection was not limited based on degree of osteoarthritis (OA) as determined radiologically by Kellgren-Lawrence (K-L) grade. For a subset of subjects, patient reported outcomes were collected up to five years including pain evaluation, patient knee global assessment, and satisfaction with the procedure.

Results: Pre-operative radiographs indicated moderate to severe osteoarthritis (K-L grades 2-4) in 65 subjects (92.8%). Significant improvements (p<0.0001) in mean VAS Pain, IKDC, mKSS and KOOS scores were observed compared with baseline. Kaplan-Meier survivorship free from conversion to knee arthroplasty was 76.2% at two years. The subset of subjects followed for five years demonstrated low pain scores and high procedure satisfaction.

Conclusion: This study presents statistically significant and clinically meaningful evidence of improvement in clinical outcomes following SCP for BMLs of the knee after two years. The survivorship rate from arthroplasty at two years was 76.2%. SCP for BMLs can relieve pain with a minimally invasive procedure and may delay the need for knee arthroplasty.