Two-Year Follow-Up and Remodeling Kinetics of ChonDux Hydrogel for Full-Thickness Cartilage Defect Repair in the Knee

Abstract

Objective: To determine performance and repair kinetics of the ChonDux hydrogel scaffold for treating focal articular cartilage defects in the knee over 24 months.

Design: This assessor-blinded trial evaluates ChonDux hydrogel scaffold implantation in combination with microfracture in 18 patients across 6 sites. Male and female patients 18 to 65 years of age with full-thickness femoral condyle defects 2 to 4 cm² in area were enrolled. Eligible patients received ChonDux treatment followed by rehabilitation. Defect volume fill was evaluated after 3, 6 (primary outcome), 12, 18, and 24 months by assessor blinded magnetic resonance imaging (MRI) analysis. Secondary outcomes were T2-weighted MRI relaxation time and patient surveys via visual analogue scale (VAS) pain and International Knee Documentation Committee (IKDC) knee function scoring.

Results: ChonDux maintained durable tissue restoration over 24 months with final defect percent fill of 94.2% ± 16.3% and no significant loss of fill volume at any time points. Tissues treated with ChonDux maintained T2 relaxation times similar to uninjured cartilage between 12 and 24 months. VAS pain scoring decreased between 1 and 6 weeks, and IKDC knee function scores improved by approximately 30.1 with ChonDux over 24 months.

Conclusion: ChonDux treatment is a safe adjunct to microfracture therapy and promotes stable restoration of full thickness articular cartilage defects for at least 24 months.

Trial registration: ClinicalTrials.gov NCT01110070.

Keywords: biomaterials; cartilage repair; microfracture; scaffold; tissue engineering.

Figure 1.

Magnetic resonance imaging (MRI) analysis of articular cartilage defect structural remodeling with ChonDux treatment. Full MRI image processing workflow to quantify defect fill are provided in the Materials and Methods section. (A) Representative image of a fully processed MRI scan of the articular defect (white arrow) at baseline before ChonDux implantation compared with (B) the same defect 6 months following ChonDux treatment. (C) Quantified defect thickness normalized to adjacent uninjured cartilage, and (D) percent defect fill normalized to initial defect size at baseline over the full 24-month time course with ChonDux treatment (mean ± SD). Dashed lines reference 100% defect thickness and fill. One-way analysis of variance with post hoc Tukey testing was performed to compare time points following ChonDux treatment, with no significant differences observed between any time points.

Figure 2.

T2-weighted magnetic resonance imaging analysis of remodeled tissue within ChonDux-treated defects compared with adjacent uninjured cartilage. T2 relaxation times for adjacent uninjured cartilage were pooled from all patients (mean ± SD). Two-way analysis of variance with post hoc Tukey testing was performed to compare ChonDux time points and to uninjured cartilage. **P < 0.01 for ChonDux versus cartilage at 3 months.

Figure 3.

Patient visual analogue scale (VAS) pain and International Knee Documentation Committee (IDKC) knee function scoring. (A) Statistics of the pain frequency and severity using the VAS at 4 to 7 days and at week 6 postoperation. The change in score was determined for each patient by subtracting the score at 4 to 7 days from the score at week 6. Graphical comparison of (B) VAS pain frequency score and (C) VAS pain severity score for microfracture and ChonDux treatment (mean ± SE). (D) IKDC knee function scores tracked over the course of the study from baseline to 24 months (mean ± SE).

Figure 4.

Correlation analysis of initial defect size to 24-month outcomes with ChonDux treatment. (A) Initial defect volumes for patients receiving ChonDux determined by magnetic resonance imaging analysis (Box plot indicates median volume, and the first and third quartiles. Whiskers extend to the minimum/maximum values). Pearson correlation analysis of initial defect size to (B) % defect fill, (C) T2 relaxation time, and (D) International Knee Documentation Committee (IKDC) scores at 24 months with ChonDux treatment. Linear regression (dotted line), with associated R² and P values.