Adjuvant injection therapies following knee cartilage repair demonstrate heterogeneous evidence: A systematic review.

Purpose: The objective of this study was to systematically review the existing literature related to adjuvant injection therapies among patients with cartilage defects of the knee joint who have undergone bone marrow stimulation procedures and ascertain their potential clinical benefits. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a search was conducted on PubMed and the Cochrane Library to identify articles documenting the utilization of adjuvant injection therapies after surgery for cartilage defects, with a minimum short-term follow-up. Animal studies, uncontrolled trials, studies lacking primary surgical intervention or those including patients with osteoarthritis were excluded. Results: Twelve articles focusing on knee cartilage defects were analysed (531 patients). Platelet-rich plasma was used in eight studies, mesenchymal stromal cells in four and hyaluronic acid in one. Injection frequency and timing varied, with the most common timing being during surgery. Primary outcome measures included subjective International Knee Documentation Committee (IKDC) and Visual Analogue Scale (VAS) scores. Subjective IKDC showed significant difference in five out of nine studies and VAS in three out of eight studies, favouring injection therapy groups. Conclusion: The present review demonstrates a large heterogeneity among included studies regarding surgical interventions, injection strategies and timing as well as outcome measures. While several studies suggest a potential benefit of adjuvant therapies, findings remain inconsistent. Due to the limited quality and comparability of the evidence, no definitive recommendations can be made at this time, highlighting the need for standardized protocols and high-quality randomized controlled trials. Level of Evidence: Level IV.