Regional and Zonal Histo‐Morphological Characteristics of the Lapine Menisci

Abstract

The menisci have crucial weight-bearing roles in the knee. Regional variations in structure and cellularity of the meniscus have only been minimally investigated. Therefore, the goal of this study was to illustrate the regional cell density, tissue area, and structure of healthy lapine menisci. Skeletally mature Flemish Giant rabbits were used for this study. Upon sacrifice, menisci were removed, fixed in formalin, and cryosectioned. Histological analysis was performed for the detection of sulfated glycosaminoglycans (GAG), collagen Types I and II, cellular density, and tissue area. ANOVA and paired t tests were used for testing of statistical significance. Glycosaminoglycan coverage of the medial meniscus significantly varied between regions, with the anterior region demonstrating significantly more GAG coverage than the posterior region. Inter- and intra-meniscal comparisons revealed variations between zones, with trends that outer zones of the medial menisci had less GAG coverage. Collagen Types I and II had marked characteristics and varying degrees of coverage across regions. Tissue area varied between regions for both medial and lateral menisci. Cellular density was dependent on region in the lateral meniscus. This is the first study to illustrate regional and zonal variation in glycosaminoglycan coverage, size, and cellular density for healthy lapine meniscal tissue. This data provides baseline information for future investigations in meniscal injury models in rabbits.

Evaluation of Meniscal Mechanics and Proteoglycan Content in a Modified Anterior Cruciate Ligament Transection Model

“…All regions with a significant decrease in staining intensity also showed a significant decrease in GAG coverage. Data from the control limb are in agreement with a previous study of healthy lapine menisci [45] as well as to GAG coverage in human studies [52]. GAG coverage was found to be relatively uniform in the lateral hemijoint, while the medial anterior region had significantly more GAG than the medial central and posterior regions.…”

“…Because mechanical and histological properties have been seen to be regionally dependent [22,[43][44][45], each meniscus was sectioned into anterior, central, and posterior regions for testing. Specimens were kept hydrated with 0.9% phosphate buffered saline (PBS) solution before and during mechanical testing.…”

In vivo transport of Gd-DTPA2- into human meniscus and cartilage assessed with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC)

“…A higher content of GAG has been reported in the central zone than in the peripheral zone of the meniscus in rabbits and humans [38,39]. Due to the need for compressive integrity, cells in the central two-thirds of the meniscus synthesize more GAG than those in the peripheral one-third [40].…”

Chronic changes in the articular cartilage and meniscus following traumatic impact to the lapine knee

“…Scoring was performed by four blinded individuals and averaged. Blinded graders were asked to assign a score from 0–4 to three different regions (anterior, central, and posterior) (Killian et al, 2010b) for both medial and lateral menisci, with 0 = normal, 1= surface damage, 2 = un-displaced tears, 3 = displaced tears, and 4 = tissue maceration. Grading, as well as mechanical and histomorphological meniscal assessments, were performed regionally to account for previously identified regional variations.…”

“…Grading, as well as mechanical and histomorphological meniscal assessments, were performed regionally to account for previously identified regional variations. (Killian et al, 2010b; Sweigart et al, 2004)…”