Do Young Park1, Byoung-Hyun Min2, Byung Hyune Choi3, Young Jick Kim4, Mijin Kim4, Haeyoung Suh-Kim5, Joon Ho Kim6. 1. Department of Anatomy, School of Medicine, Ajou University, Suwon, South Korea. 2. Department of Orthopaedic Surgery, School of Medicine, Ajou University, Suwon, South Korea Cell Therapy Center, School of Medicine, Ajou University, Suwon, South Korea bhmin@ajou.ac.kr. 3. Department of Biomedical Sciences, Inha University College of Medicine, Incheon, South Korea. 4. Cell Therapy Center, School of Medicine, Ajou University, Suwon, South Korea. 5. Department of Anatomy, School of Medicine, Ajou University, Suwon, South Korea Neuroscience Graduate Program, School of Medicine, Ajou University, Suwon, South Korea BK21-Division of Cell Transformation and Restoration, School of Medicine, Ajou University, Suwon, South Korea. 6. Department of Orthopaedic Surgery, School of Medicine, Ajou University, Suwon, South Korea.
Abstract
BACKGROUND: Fibrocartilage metaplasia in tendons and ligaments is an adaptation to compression as well as a pathological feature during degeneration. Medial meniscus posterior roots are unique ligaments that resist multidirectional forces, including compression. PURPOSE: To characterize the degeneration of medial meniscus posterior root tears in osteoarthritic knees, with an emphasis on fibrocartilage and calcification. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Samples of medial meniscus posterior roots were harvested from cadaveric specimens and patients during knee replacement surgery and grouped as follows: normal reference, no tear, partial tear, and complete tear. Degeneration was analyzed with histology, immunohistochemistry, and real-time polymerase chain reaction. Uniaxial tensile tests were performed on specimens with and without fibrocartilage. Quantifiable data were statistically analyzed by the Kruskal-Wallis test with the Dunn comparison test. RESULTS: Thirty, 28, and 42 samples harvested from 99 patients were allocated into the no tear, partial tear, and complete tear groups, respectively. Mean modified Bonar tendinopathy scores for each group were 3.97, 9.31, and 14.15, respectively, showing a higher degree of degeneration associated with the extent of the tear (P < .05 for all groups). The characterization of root matrices revealed an increase in fibrocartilage according to the extent of the tear. Tear margins revealed fibrocartilage in 59.3% of partial tear samples and 76.2% of complete tear samples, with a distinctive cleavage-like shape. Root tears with a similar shape were induced within fibrocartilaginous areas during uniaxial tensile testing. Even in the no tear group, 56.7% of samples showed fibrocartilage in the anterior margin of the root, adjacent to the meniscus. An increased stained area of calcification and expression of the ectonucleotide pyrophosphatase/phosphodiesterase 1 gene were observed in the complete tear group compared with the no tear group (P < .0001 and P = .24, respectively). CONCLUSION: Fibrocartilage and calcification increased in medial meniscus posterior roots, associated with the degree of the tear. Both findings, which impair the ligament's resistance to tension, may play a pivotal role during the pathogenesis of degenerative meniscus root tears in osteoarthritic knees. Fibrocartilage and calcification may be useful as diagnostic markers as well as markers of degeneration, which may aid in determining the treatment modality in meniscus root tears. The presence of fibrocartilage in intact roots may suggest an impending tear in osteoarthritic knees.
BACKGROUND:Fibrocartilage metaplasia in tendons and ligaments is an adaptation to compression as well as a pathological feature during degeneration. Medial meniscus posterior roots are unique ligaments that resist multidirectional forces, including compression. PURPOSE: To characterize the degeneration of medial meniscus posterior root tears in osteoarthritic knees, with an emphasis on fibrocartilage and calcification. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Samples of medial meniscus posterior roots were harvested from cadaveric specimens and patients during knee replacement surgery and grouped as follows: normal reference, no tear, partial tear, and complete tear. Degeneration was analyzed with histology, immunohistochemistry, and real-time polymerase chain reaction. Uniaxial tensile tests were performed on specimens with and without fibrocartilage. Quantifiable data were statistically analyzed by the Kruskal-Wallis test with the Dunn comparison test. RESULTS: Thirty, 28, and 42 samples harvested from 99 patients were allocated into the no tear, partial tear, and complete tear groups, respectively. Mean modified Bonar tendinopathy scores for each group were 3.97, 9.31, and 14.15, respectively, showing a higher degree of degeneration associated with the extent of the tear (P < .05 for all groups). The characterization of root matrices revealed an increase in fibrocartilage according to the extent of the tear. Tear margins revealed fibrocartilage in 59.3% of partial tear samples and 76.2% of complete tear samples, with a distinctive cleavage-like shape. Root tears with a similar shape were induced within fibrocartilaginous areas during uniaxial tensile testing. Even in the no tear group, 56.7% of samples showed fibrocartilage in the anterior margin of the root, adjacent to the meniscus. An increased stained area of calcification and expression of the ectonucleotide pyrophosphatase/phosphodiesterase 1 gene were observed in the complete tear group compared with the no tear group (P < .0001 and P = .24, respectively). CONCLUSION: Fibrocartilage and calcification increased in medial meniscus posterior roots, associated with the degree of the tear. Both findings, which impair the ligament's resistance to tension, may play a pivotal role during the pathogenesis of degenerative meniscus root tears in osteoarthritic knees. Fibrocartilage and calcification may be useful as diagnostic markers as well as markers of degeneration, which may aid in determining the treatment modality in meniscus root tears. The presence of fibrocartilage in intact roots may suggest an impending tear in osteoarthritic knees.
Authors: Anna Cristina de Farias Marques; Regiane Albertini; Andrey Jorge Serra; Evela Aparecida Pereira da Silva; Vanessa Lima Cavalcante de Oliveira; Luciana Miatto Silva; Ernesto Cesar Pinto Leal-Junior; Paulo de Tarso Camillo de Carvalho Journal: Lasers Med Sci Date: 2016-09-13 Impact factor: 3.161