TITLE:
The Extension Rate of the Medial Collateral Ligament of the Knee Joint during the Valgus Stress Test: Two Case Reports
AUTHORS:
Yuichi Takata, Koji Iwamoto, Sadanori Oshiro, Mitsuhiro Iijima
KEYWORDS:
Medial Collateral Ligament, Valgus Stress Test, Extension Rate
JOURNAL NAME:
Open Journal of Therapy and Rehabilitation,
Vol.9 No.1,
February
8,
2021
ABSTRACT: This study aimed to evaluate the influence of measuring the length of the
medial collateral ligament (MCL) to compare the MCL burden when the knee joint
is placed under valgus stress in the open and closed and closed kinetic chain. Two examiners conducted the examination. The MCL length was measured using
ultrasonography. Two subjects were measured in unload bearing and load-bearing
positions, with and without valgus stress test at the knee joint extension and
30° flexion, under eight different measurement conditions. The MCL of the
subject was delineated in the longitudinal direction using an ultrasound
system. The attachment points of the medial femoral and tibial condyle of the
MCL were identified, and the ligament length was measured. The MCL rate before
and after the valgus stress test in the loading and unloading positions was
calculated. The MCL length increased by an average of 8.9% when the
external stress test was performed in the non-weight bearing and knee extension
positions and by an average of 17.0% when external stress was applied in the
non-weight bearing and knee flexion positions. The MCL length increased by an
average of 12.2% when the external stress test was performed in the
load-bearing and knee extension positions and an average of 8.9% when the
valgus stress test was applied in load-bearing and knee flexion positions. In
conclusion, the effect of valgus stress on the MCL differs between load-bearing
and non-load-bearing positions. It is considered that the dynamic stabilization
mechanism works in the knee joint flexion position in the load position and
works simultaneously as the static stabilization mechanism, which limits the
knee joint valgus and reduces the extension rate of MCL. Therefore, this study
reconsiders the shifting of traditional therapy from open kinetic chain to
close kinetic chain.