Cartilage repair in the knee with subchondral drilling augmented with a platelet-rich plasma-immersed polymer-based implant.

Purpose: The aim of our study was to analyse the clinical and histological outcome after the treatment of focal cartilage defects in non-degenerative and degenerative knees with bone marrow stimulation and subsequent covering with a cell-free resorbable polyglycolic acid-hyaluronan (PGA-HA) implant immersed with autologous platelet-rich plasma (PRP).

Methods: Fifty-two patients (mean age 44 years) with focal chondral defects in radiologically confirmed non-degenerative or degenerative knees were subjected to subchondral drilling arthroscopically. Subsequently, defects were covered with the PGA-HA implant immersed with autologous PRP. At 2-year follow-up, the patients' situation was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and compared to the pre-operative situation and 3-12-month follow-up. Biopsies (n = 4) were harvested at 18-24 months after implantation and were analysed by histology and collagen type II immune staining.

Results: At 1- and 2-year follow-up, the KOOS showed clinically meaningful and significant (p < 0.05) improvement in all subcategories compared to baseline and to 3-month follow-up. There were no differences in KOOS data obtained after 2 years compared to 1 year after the treatment. Histological analysis of the biopsy tissue showed hyaline-like to hyaline cartilage repair tissue that was rich in cells with a chondrocyte morphology, proteoglycans and type II collagen.

Conclusions: Covering of focal cartilage defects with the PGA-HA implant and PRP after bone marrow stimulation improves the patients' situation and has the potential to regenerate hyaline-like cartilage.

Level Of Evidence: Case series, Level IV.