Global Variation in Studies of Articular Cartilage Procedures of the Knee: A Systematic Review

Objective: The objective of this study was to determine whether there are significant differences in terms of indications, techniques, patient variables, and objective and subjective outcome scores as a function of the geographic locale of published studies of knee articular cartilage surgery. Methods: An electronic database search was performed of clinical studies evaluating knee articular cartilage procedures from 2000 to 2021. Studies were separated into global regions (Europe, Asia, North America, and South America) based on the study country. All cartilage-based treatments in each region were recorded. Patient age and sex, mechanism of injury, cartilage lesion size and location, follow-up time, failure rate, and knee outcome scores utilized were summarized and compared by region. Results: A total of 2,923 studies were analyzed. Eighty level 1 and 2 studies met the inclusion criteria. The majority were from Europe (n = 60), followed by Asia (n = 11), North America (n = 7), and South America (n = 2). The majority of procedures in European and North American studies were cell-based and marrow-stimulation procedures. In Asian studies, the most common procedures were marrow-stimulation, experimental, and biologic procedures as defined by the authors. Asian countries had a higher proportion of females (P < 0.001) and an overall older patient population (P < 0.001). Regional variation was also seen in terms of lesion location, mechanism of injury, and failure rate. Conclusion: Most high-level evidence for articular cartilage-based procedures of the knee comes from European countries. These studies vary by patient age and sex, anatomic location, and mechanism of injury. Global variation should be taken into consideration when interpreting and applying studies of knee articular cartilage surgery.