Comparison of Hydrogel-Based Autologous Chondrocyte Implantation Versus Microfracture: A Propensity Score Matched-Pair Analysis

Philipp Niemeyer; Peter Angele; Robert C Spiro; Alexandra Kirner; Christoph Gaissmaier

doi:10.1177/23259671231193325

Comparison of Hydrogel-Based Autologous Chondrocyte Implantation Versus Microfracture: A Propensity Score Matched-Pair Analysis

Orthop J Sports Med. 2023 Aug 18;11(8):23259671231193325. doi: 10.1177/23259671231193325. eCollection 2023 Aug.

Authors

Philipp Niemeyer^{1

2}, Peter Angele^{3

4}, Robert C Spiro⁵, Alexandra Kirner⁶, Christoph Gaissmaier⁶

Affiliations

¹ OCM Orthopädische Chirurgie München, Munich, Germany.
² Department of Orthopedics and Trauma Surgery, University Medical Center Freiburg, Albert Ludwig University of Freiburg, Freiburg, Germany.
³ Sporthopaedicum Regensburg, Regensburg, Germany.
⁴ Department of Trauma Surgery, University Medical Centre Regensburg, Germany.
⁵ Aesculap Biologics LLC, Breinigsville, Pennsylvania, USA.
⁶ TETEC-Tissue Engineering Technologies AG, Reutlingen, Germany.

Abstract

Background: Few studies exist for large defects comparing matrix-associated autologous chondrocyte implantation (M-ACI) with other cartilage repair methods due to the limited availability of suitable comparator treatments.

Purpose: To compare the clinical efficacy of a novel hydrogel-based M-ACI method (NOVOCART Inject plus) versus microfracture (MFx) in patients with knee cartilage defects.

Study design: Cohort study; Level of evidence, 3.

Methods: Propensity score matched-pair analysis was used to compare the 24-month outcomes between the M-ACI treatment group from a previous single-arm phase 3 study and the MFx control group from another phase 3 study. Patients were matched based on preoperative Knee injury and Osteoarthritis Outcomes Score (KOOS), symptom duration, previous knee surgeries, age, and sex, resulting in 144 patients in the matched-pair set (72 patients per group). The primary endpoint was the change in least-squares means (Δ_LSmeans) for the KOOS from baseline to the 24-month assessment.

Results: Defect sizes in the M-ACI group were significantly larger than in the MFx group (6.4 versus 3.7 cm²). Other differences included defect location (no patellar or tibial defects in the MFx group), number of defects (33.3% with 2 defects in the M-ACI group versus 9.7% in the MFx group), and defect cause (more patients with degenerative lesions in the M-ACI group). The M-ACI group had higher posttreatment KOOS (M-ACI versus MFX: 81.8 ± 16.8 versus 73.0 ± 20.6 points) and KOOS Δ_LSmeans from baseline to 24 months posttreatment (M-ACI versus MFX: 36.9 versus 26.9 points). Treatment contrasts in KOOS Δ_LSmeans from baseline indicated statistical significance in favor of M-ACI from 3 to 24 months posttreatment (P = .0026). Significant and clinically meaningful differences in favor of M-ACI at 24 months were also found regarding International Knee Documentation Committee (IKDC) score Δ_LSmeans from baseline (37.8 versus 30.4 points; P = .0334), KOOS responder rates at 24 months (≥10-point improvement from baseline; 94.4% versus 65.3%; P < .0001), IKDC responder rates at 24 months (>20.5-point improvement from baseline; 83.3% versus 61.1%, P = .0126) and MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) score in a subgroup of patients (LS means, 86.9 versus 69.1; P = .0096).

Conclusion: In this exploratory analysis, M-ACI using an in situ crosslinked hydrogel demonstrated superior clinical and structural (MOCART) 24-month outcomes compared with MFx in patients with knee cartilage defects.

Keywords: autologous chondrocyte implantation; cartilage defect; hydrogel; knee joint; large lesions.