Current Techniques for Processing Osteochondral Allografts Are Variable: A Systematic Review

To investigate the current optimal processing and storage protocols for fresh cold-stored osteochondral allografts (OCAs) used for resurfacing osteochondral defects in the knee.

Using the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines, 3 databases (PubMed, Embase, and Scopus) were queried for peer-reviewed articles on OCA storage and processing techniques. Articles were excluded if performed on nonhuman subjects or were narrative or systematic reviews, meta-analyses, or other forms of secondary sources. In vivo data included study type, population size, follow-up time, type, site and location of injury, description of surgery, description of postoperative rehabilitation, and outcome criteria used. Ex vivo data collection included tissue source and type, storage procedure including temperature, media changes, gas environment, storage solution including type of solution and additive used, cell viability methodology, and outcomes methodology.

In total, 386 studies were screened between the 3 databases, with 27 studies satisfying all criteria. Eight human studies were included, with mean Modified Coleman Methodology Score of 48.38 ± 5.73. In total, 397 total patients were included with a mean of 49.6 patients per study. Five of the 8 studies had follow-up greater than 24 months. Three articles were retrospective studies, 4 were case series, 1 was a prospective cohort. Four articles were Level III evidence, 4 articles were Level IV evidence. In addition, 19 ex vivo human studies were included. A total of 78.95% of studies included grafts stored at 4°C or 1 to 10°C, 31.58% investigated 37°C, and 21.05% investigated room temperature. In total, 19 different storage media were investigated, with 68.42% including various additives.

OCA storage at 4°C remains the most common temperature with the most evidence-based research. However, investigation of OCAs at 37°C and room temperature, particularly those stored with proprietary protocol such as the Missouri Osteochondral Preservation System, have shown promising results at improved maintenance of viable chondrocyte density. Variability in storage media remains without clear consensus.

A variety of methodologies are used for OCAs, and the best strategies are not well understood. There is a need to compile the available evidence from in vivo and ex vivo studies of OCAs to resolve conflicts regarding various available methodologies and provide better understanding of current techniques.