Tissue-specific changes in size and shape of the ligaments and tendons of the porcine knee during post-natal growth

Abstract

Prior studies have analyzed growth of musculoskeletal tissues between species or across body segments; however, little research has assessed the differences in similar tissues within a single joint. Here we studied changes in the length and cross-sectional area of four ligaments and tendons, (anterior cruciate ligament, patellar tendon, medial collateral ligament, lateral collateral ligament) in the tibiofemoral joint of female Yorkshire pigs through high-field magnetic resonance imaging throughout growth. Tissue lengths increased by 4- to 5-fold from birth to late adolescence across the tissues while tissue cross-sectional area increased by 10–20-fold. The anterior cruciate ligament and lateral collateral ligament showed allometric growth favoring change in length over change in cross-sectional area while the patellar tendon and medial collateral ligament grow in an isometric manner. Additionally, changes in the length and cross-sectional area of the anterior cruciate ligament did not increase as much as in the other ligaments and tendon of interest. Overall, these findings suggest that musculoskeletal soft tissue morphometry can vary within tissues of similar structure and within a single joint during post-natal growth.

Age‐ and sex‐specific differences in ACL and ACL bundle size during adolescent growth

“…The length of the vector between the centroids of the tissue‐specific tibial insertion and the femoral ACL insertion was calculated using a custom code for each tissue (Figure 2). CSA was calculated as described in a previous paper 23,24 . Briefly, each the tissue model was imported into Matlab, rotated such that the longest tissue axis matched the z‐ axis of a coordinate system, and then the surface was collapsed onto x ‐ y planes at 1 mm increments along the z ‐axis.…”

“…CSA was calculated as described in a previous paper. 23,24 Briefly, each the tissue model was imported into Matlab, rotated such that the longest tissue axis matched the z-axis of a coordinate system, and then the surface was collapsed onto x-y planes at 1 mm increments along the z-axis. The CSA was then calculated as the average of the areas measured within these 2D features in the central 50% of the tissue.…”

Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how)

“…The rodent ACL is positioned within the knee in comparable anatomical location to humans, but the hierarchical organization of the ACL is less complex in rodents, especially mice, compared to humans 9 . However, several studies, 5,10–13 including our recent work, 14–16 have shown that the ACL still serves as a primary restraint to tibial anterior translation (Figure 2). Therefore, these anatomical limitations do not change the primary function of the ligament or the ability of rodent models to answer key mechanistic and biology questions.…”

“…Longitudinal studies with fluorescent reporters and in vivo whole animal imagers are also an option for rodent studies but remain uncommon in large animal studies. Moreover, noninvasive imaging techniques, such as magnetic resonance imaging or ultrasound [3][4][5][6] can be done using similar sequences and at similar resolution in large animal models as used for humans, 7,8 and joint kinematics are more commonly done in large animal species. In small animal models, longitudinal imaging of bone and the enthesis via micro computed tomography and soft tissues with high resolution 7−10 T MRI and/or 50−55 MHz ultrasonography are also possible but the resolution can be limited by the small size of the rodent tendon and ligament.…”

Equine subchondral lucencies: Knowledge from the medial femoral condyle

“…4,18 Pigs from 1.5 to 3 months of age have greater translation and rotation in the stifle joint as compared to adolescents (4.5-18 months). 38 In pigs, the anterior cruciate ligament is the primary stabilizer of the stifle, and its anatomy changes substantially during early development, gaining substance and changing orientation, affecting joint kinematics, 38,39 and it is likely that the same is true in foals less than 6 months of age. 18 Equine stifle joint kinematics at any age is challenging to investigate, and available information is limited to an unloaded ex vivo study of femur and tibias from adult horses.…”