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

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.既往研究已针对不同物种间或躯体节段间的肌肉骨骼组织生长特征展开分析，但鲜有研究针对单个关节内相似组织的差异开展评估。本研究借助高场磁共振成像（high-field magnetic resonance imaging）技术，对雌性约克夏猪胫股关节（tibiofemoral joint）内的四条韧带与肌腱——前十字韧带（anterior cruciate ligament）、髌腱（patellar tendon）、内侧副韧带（medial collateral ligament）、外侧副韧带（lateral collateral ligament）——在整个生长周期中的长度及横截面积变化进行了系统观测。所有受试组织的长度从出生至青春期末均增长4至5倍，而横截面积增幅则达10至20倍。前十字韧带与外侧副韧带呈现异速生长（allometric growth）模式，更倾向于长度而非横截面积的变化；而髌腱与内侧副韧带则采用等距生长（isometric growth）模式。此外，前十字韧带的长度与横截面积增幅均低于其余目标韧带及肌腱。综上，本研究结果表明，在出生后的生长过程中，结构相似的组织以及单个关节内的肌肉骨骼软组织形态计量学（musculoskeletal soft tissue morphometry）特征可存在差异。