Effects of different meniscectomies on tibial rotation of the knee

Objective To investigate the effects of different extents and parts of meniscectomy on tibial rotation of the knee. Methods Six pairs of fresh intact cadavcric knees without surgical history were used in this investigation.They were randomly divided into a control group (group A) and 5 experimental groups (B,C,D,E and F).Group A was for intact control,group B for medial partial meniscectomy of the anterior horn,group C for medial partial meniscectomy of the posterior horn,group D for lateral partial meniscectomy of the anterior horn, group E for total medial meniscectomy and group F for total lateral meniscectomy.For each group 4 specimens were used,for the 4 knees first used in groups A,B and D were then used in groups C,E and F,respectively.The full isokinetic knee cycle from extension to flexion was simulated by a Staubli robot.The tibial rotations were measured by an angle measuring instrument (Nemicon,Japan) before and after different meniscectomies. Results The tibial rotations at the knee flexion of 0°,10°,20°,30°,60° and 90° were respectively 4.9°±0.8°,9.2°±0.8°,11.4°±0.8°,12.1°±0.5°and 12.4°± 0.5° in the control group.The tibial rotations at the knee flexion of 0° to 90° were not significantly different between the control and partial meniscectomy groups and between the partial meniscectomy groups as well ( P ＞ 0.05),but were significantly different between the total meniscectomy groups and the partial meniscectomy groups and between the total meniscectomy groups as well(P ＜0.05).The tibial rotations were not significantly different between the control and total meniscectomy groups at the knee flexion of 30° to 90° ( P ＞ 0.05),but were significantly different between the 2 groups at the knee flexion of 0°to 30°( P ＜ 0.05). Conclusions The partial meniscectomy may not have a significant impact on the tibial rotation when the knee is in flexing motion.The total meniscectomy may have a significant impact on the tibial rotation when the knee is in flexing motion of 30°to 90°. Key words: Knee joints; Menisci, tibial; Biomechanics; Rotation