Changes of the mechanoreceptors in the different state remnant stump after ACL rupture

Abstract

Objective To investigate the changes of mechanoreceptors in the different state remnant stumps after anterior cruciate ligament (ACL) rupture. Methods From March 2013 to December 2015, fifty-seven cases of complete ACL rupture were collected to record the time interval from injury to surgery.The patients were divided into two groups according to preoperative kneelax joint measurement results: ≤6 mm group (group 1) and>6 mm group (group 2). The morphology of each ligament stump in the two groups was recorded.After H&E staining and immunohistochemical labeling, the morphology, type, and quantity of the mechanoreceptors in the ligament stump were observed under an optical microscope.The relationship among the changes of the mechanoreceptors in the remnant stumps and the morphology of the ligament stump, the affected knee stability and the time from injury to surgery were analyzed. Results Twenty specimens were included in group 1.While 37 specimens were included in group 2.There was significant difference between the two groups in the distributions of the 4 types of the remnant stumps (P=0.000). There was significant difference between the two groups in the distributions of the 4 types of mechanoreceptors (P=0.002). The number of the mechanoreceptors was positively correlated with the affected knee stability (r=0.63, P=0.018). There was no significant correlation between the number of the mechanoreceptors and the time from injury to surgery in group1(r=-0.37, P=0.136), while the number of the mechanoreceptors was negatively correlated with the time from injury to surgery in group 2 (r=-0.51, P=0.022). Conclusion After ACL rupture, the ligament stump in some patients still connect the femur and the tibia in the joint cavity, and exert mechanical stability function, which can retain the mechanoreceptors in the tissue for a long time. Key words: Knee joint; Anterior cruciate ligament; Remnant; Mechanoreceptor