In a „true“ valgus knee the lateral femoral condyle is smaller in both the vertical and anteroposterior dimensions and lateral soft tissue structures are contracted. In a „false“ valgus knee there is no mismatch between anteroposterior dimensions of both condyles. The aim of the study was to preoperatively analyse patterns of passive movement of valgus knees with imageless navigation system to optimise surgical approach during subsequent total knee replacement (TKR). TKR were prospectively performed in 50 valgus knees. After the data registration process, the kinematic analysis was performed by passive movement of the knee. The mechanical axis was recorded at 0°, 30°, 60°, 90°, and 120° of flexion. The valgus deformity persistent through the whole range of motion was called „true“ and the valgus deformity passing into varus with flexion was called „false“. The pre-operative valgus deformity in extension ranged from 13° to 4° (mean 7.8°). We observed „true“ valgus type deformity during passive range of movement in 34 cases (68%) and „false“ type of kinematics in 16 cases (32%). The average value of valgus deviation in extension in „true“ group was 7.9° (range 13° to 4°) and in „false“ group 7.5° (range 9° to 6°). The mean difference between axis deviation in 0° to 120° range of flexion was 5.5° (range 10° to 1°) in the „true“ valgus group. In the „false“ valgus group the varus deviation was observed in 90° of flexion in all cases and mean difference between axis deviation in 0° to 120° range of flexion was 12.0° (range 14° to 10°). Computer navigation can easily help to identify the character of valgus deformity („true“ or „false“) just before skin incision. In „true“ valgus deviation lateral approach may be necessary for appropriate soft tissue balancing during TKR surgery.
The biomechanical function of the anteromedial
(AM) and posterolateral (PL) bundles of the anterior cruciate ligament
(ACL) remains controversial. Some studies report that the AM bundle
stabilises the knee joint in anteroposterior (AP) translation and
rotational movement (both internal and external) to the same extent
as the PL bundle. Others conclude that the PL bundle is more important
than the AM in controlling rotational movement. The objective of this randomised cohort study involving 60 patients
(39 men and 21 women) with a mean age of 32.9 years (18 to 53) was
to evaluate the function of the AM and the PL bundles of the ACL
in both AP and rotational movements of the knee joint after single-bundle
and double-bundle ACL reconstruction using a computer navigation
system. In the double-bundle group the patients were also randomised
to have the AM or the PL bundle tensioned first, with knee laxity
measured after each stage of reconstruction. All patients had isolated
complete ACL tears, and the presence of a meniscal injury was the
only supplementary pathology permitted for inclusion in the trial.
The KT-1000 arthrometer was used to apply a constant load to evaluate
the AP translation and the rolimeter was used to apply a constant
rotational force. For the single-bundle group deviation was measured
before and after ACL reconstruction. In the double-bundle group
deviation was measured for the ACL-deficient, AM- or PL-reconstructed
first conditions and for the total reconstruction. We found that the AM bundle in the double-bundle group controlled
rotation as much as the single-bundle technique, and to a greater
extent than the PL bundle in the double-bundle technique. The double-bundle
technique increases AP translation and rotational stability in internal
rotation more than the single-bundle technique.