Kinematic analysis of knee varus and rotation movements at the initial stance phase with severe osteoarthritis of the knee

BACKGROUND

The purposes of this study were to understand the kinematics changes in the frontal and horizontal planes with severe medial knee OA at the stance phase and to examine the relationship between varus and rotational movements.

METHODS

The OA group comprised 18 knees in 12 subjects (five men, seven women) with a Kellgren-Lawrence grade of three or four in at least one knee. From the results of gait analysis, we calculated Spearman rank-correlation coefficients for the following items: varus angle at initial contact (IC); varus angle at loading response (LR); amount of varus thrust from IC to LR; rotational angle at IC; rotational angle at LR and amount of rotational angle change from IC to LR.

RESULTS

The results indicated that, as the external rotation angle at IC and internal rotational movement from IC to LR increased, the maximum varus angle to LR showed a tendency to become large. In addition, varus thrust showed a tendency to become larger as the external rotation angles increased at IC and LR. The subjects with severe knee OA showed a strong correlation between the knee varus angle at IC and at LR. Furthermore, an increase in movement to internal rotation of the knee during the initial stance phase increased the knee varus angle at LR.

CONCLUSIONS

The control of the rotational movement according to the extent of varus thrust during the initial stance phase may have possible effects to decrease the load on the medial compartment of the knee.

AM bundle controls the anterior-posterior and rotational stability to a greater extent than the PL bundle - a cadaver study

BACKGROUND

The purpose of this study was to evaluate the influence of both bundles of the anterior cruciate ligament (ACL) on knee stability, anterior-posterior translation (APT) and internal (IR) and external (ER) rotation in cadaveric knees using a computer navigation system.

METHODS

The APT, IR, and ER of the knees were recorded in the intact condition, the anterolateral bundle (AM) or the posterolateral bundle (PL) deficit condition and in the ACL-deficient condition. The KT-1000 arthrometer was used for APT evaluation. The measurement of rotational movements was done using a rollimeter. All tests were performed at 30°, 60° and 90° of flexion.

RESULTS

At 30° of flexion: In the intact knee APT was 5.8mm, IR 12.1°, ER 10.1°. After the AM was cut, the APT increased to 9.1mm, IR to 13.9° and ER to 12.6°. After the PL was cut, the APT was 6.4mm, IR 13.1° and ER 10.6°. After the AM and PL were cut, the APT was 10.8mm, IR 15.7° and the ER was 12.9° on average.

CONCLUSIONS

The AM has a greater impact on the APT than the PL in all knee joint flexion angles. The PL does not resist the rotational stability more than the AM. The rotational stability is better controlled by both bundles of ACL as compared to one bundle of the ACL.

CLINICAL RELEVANCE

This study acknowledges the fact that the both bundles of the ACL are importants for AP and rotational stability of the knee joint.