Chondrogenesis with Stem Cells in Massive Chondral Defects: A Randomized Controlled Trial

OBJECTIVES: The purpose of this study was to evaluate the safety and efficacy of intra-articular injections of autologous peripheral blood stem cells (PBSC) with hyaluronic acid (HA) after arthroscopic subchondral drilling into massive chondral defects of the knee joint and to determine whether PBSC therapy can improve functional outcome and reduce pain of the knee joint better than the standard of care. METHODS: This is a dual centre, US-FDA phase IIB randomized controlled trial (RCT). Sixty-nine patients age 18-55 years with International Cartilage Repair Society (ICRS) grade 3 and 4 chondral lesions (size ≥ 3cm(2)) of the knee joint were randomized equally into (i) control group receiving intra-articular injections of HA plus physiotherapy (standard of care) and (ii) intervention group receiving arthroscopic subchondral drilling into chondral defects and postoperative intra-articular injections of PBSC with HA. The co-primary efficacy endpoints are subjective International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS)-pain subdomain measured at month-24. The secondary efficacy endpoints include all other KOOS subdomains, Numeric Rating Scale (NRS) and Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scores. RESULTS: At 24 months, the mean IKDC scores for the control and intervention groups were 48.1 and 65.6, respectively (P < 0.0001). The mean for KOOS-pain subdomain scores were 59.0 (control) and 86.0 (intervention) with P < 0.0001. All other KOOS subdomains, NRS and MOCART scores were statistically significant (P < 0.0001) at month-24. Figure 1 shows the bar graphs of the co-primary endpoints. Figure 2 shows the MRI images of: (A) ‘Bone-on-bone’ chondral defects of the lateral femoral condyle (white arrows) and lateral tibial plateau (yellow arrows) following subchondral drilling, with corresponding arthroscopic images and (B) the same lesions at 2 years after surgery showing full thickness articular cartilage regeneration There were no notable adverse events that are unexpected and related to the study drug or procedures. CONCLUSIONS: Arthroscopic subchondral drilling into massive chondral defects of the knee joint followed by postoperative intra-articular injections of autologous PBSC with HA is safe and showed a significant improvement of clinical and radiological scores as compared to the standard of care.