Articular cartilage histological scoring systems: state of the art.

Aim: Histological evaluation of cartilage plays a fundamental role in the experimental field of cartilage repair. Numerous scoring systems for evaluation of articular cartilage have been proposed. They are used to describe the quality of osteoarthritic, in vivo repaired or in vitro engineered tissue. This review aims to provide an overview of past and currently used histological scoring systems. Methods: The authors obtained their data by reviewing the English literature on the histological scoring systems that had been applied and/or discussed. PubMed, Embase and the Cochrane Library were used for the search (syntax: histological AND (scoring* OR grading * OR assessment* OR scale*) AND cartilage. Last search: January 31st, 2013.The scores were classified into the following categories: 1) Main Scores (scores that have been validated and/or used in more than one study by different authors); 2) Minor Scores (scores used just in one study or in more than one study by the same authors); and 3) Recent Scores (introduced after 2009). Results: A large variety of histological scoring systems for the assessment of articular cartilage is available in the literature and some of them are also validated. The Main Scores include: Mankin, OARSI, O'Driscoll for in vivo cartilage repair, Oswestry, ICRS, ICRSII, Bern, Pineda, Wakitani, Fortier, and Sellers scores. The following are included in the Minor Score section: Colombo, Bendele and Hulman, Huang, Frisbie, Peterson, Knutsen, O'Driscoll for tissue-engineered cartilage, Freemont, Yagi, Saal, Dorokta, Hotta, and Nettles scores. The Recent Scores include: McNulty, Kock, and Zeng scores. The ideal score still does not exist. Different parameters can be used in choosing a score for an experimental study and these include: 1) diffusion of the score; 2) validation; 3) easiness and completeness; 4) type of tissue to evaluate (arthritic, in vivo repaired, or in vitro generated cartilage); 5) type and size of the samples to evaluate (human biopsies, entire animal joint). Conclusion: In the histological evaluation of osteoarthritis, the authors recommend widely used scores, such as Mankin and OARSI scores. In the in vivo (animal model) evaluation of cartilage, the authors recommend comprehensive (scores with a wide of final points) and well recognised scores, as ICRSII and O'Driscoll. In the in vivo (human biopsy model) evaluation of cartilage, the authors recommend the Oswestry score. In the tissue-engineered cartilage evaluation, the Bern score is suggested due to its easiness and popularity.