Second-Look Arthroscopic Evaluation of Cartilage Lesions After Mesenchymal Stem Cell Implantation in Osteoarthritic Knees

Abstract

Background: Cartilage regenerative procedures have been receiving increased interest because of their potential to alter the progression of osteoarthritis (OA). The application of mesenchymal stem cells (MSCs) has been proposed as a new treatment option for OA based on the ability of these cells to differentiate into chondrocytes.

Purpose: To investigate the clinical and second-look arthroscopic outcomes of MSC implantation and to identify prognostic factors associated with this treatment.

Study design: Case series; Level of evidence, 4.

Methods: This study retrospectively evaluated 37 knees examined using second-look arthroscopic surgery after MSC implantation for cartilage lesions in OA knees. Clinical outcomes were evaluated according to the International Knee Documentation Committee (IKDC) score and Tegner activity scale, and cartilage repair was assessed using International Cartilage Repair Society (ICRS) grading. Statistical analyses were performed to identify various prognostic factors associated with the clinical and second-look arthroscopic outcomes.

Results: The mean patient age was 57.4 years (range, 48-69 years), the mean follow-up period was 26.5 months (range, 24-34 months), the mean body mass index (BMI) was 26.3 kg/m2 (range, 19.8-31.2 kg/m2), and the mean lesion size was 5.4 ± 2.9 cm2 (range, 2.3-8.9 cm2). The mean IKDC and Tegner activity scale scores were significantly improved from 38.0 ± 7.8 to 61.0 ± 11.0 and from 2.5 ± 0.5 to 3.6 ± 0.7, respectively (P < .001 for both). According to the ICRS overall repair grades at second-look arthroscopic surgery, 2 of the 37 lesions (5%) were grade I (normal), 7 (19%) were grade II (near normal), 20 (54%) were grade III (abnormal), and 8 (22%) were grade IV (severely abnormal). In terms of overall patient satisfaction with the operation, 33 (94%) patients reported good to excellent satisfaction. High BMI (≥27.5 kg/m2) and large lesion size (≥5.4 cm2) were found to be significant predictors of poor clinical and arthroscopic outcomes (P < .05 for both). Other prognostic factors, including patient age, sex, cartilage lesion location, and presence of subchondral cysts, did not significantly influence the outcomes (P > .05).

Conclusion: The outcomes of MSC implantation for cartilage repair in OA knees seem encouraging; high BMI and large lesion size are important factors affecting outcomes. Although still in the early stages of application, MSC implantation for cartilage repair may have great potential for the treatment of OA knees. However, second-look arthroscopic findings revealed that 76% had the repair rated as abnormal or severely abnormal by ICRS standards. The development of an advanced surgical procedure with tissue-engineered scaffolds may be needed to treat patients with large cartilage lesions.

Keywords: implantation; knee; mesenchymal stem cell; osteoarthritis; second-look arthroscopic surgery.