This retrospective study was performed to relate tunnel position as measured by plain
radiographs and magnetic resonance imaging (MRI) to residual pivot shift and to determine
its clinical relevance after anterior cruciate ligament reconstruction via central
quadriceps tendon autograft.
We reviewed 137 arthroscopic anterior cruciate ligament reconstructions via quadriceps
tendon autograft with a minimum of 2 years' follow-up. Clinical results were evaluated
by use of the Lachman test, pivot-shift test, Lysholm score, and Cybex dynamometer
(Lumex, Ronkonkoma, NY). Anterior tibial translation was measured with the KT-1000
arthrometer (MEDmetric, San Diego, CA). Patients were classified into 3 groups based
on postoperative pivot-shift and Lachman test findings: group I, both negative; group
II, negative Lachman test and positive pivot shift; and group III, both positive.
The radiographic analysis was performed via the angle between the tibial and femoral
tunnels on plain anteroposterior radiographs, the angle between the tibial tunnel
and anterior tibial cortex on the lateral view, and the femoral and tibial tunnel
location by use of the ratio method. Postoperative knee MRI was performed, and the
angle between the intercondylar anteroposterior axis and femoral tunnel on the axial
view and the angle between the joint line and the graft on the oblique coronal and
sagittal views were measured.
There were 100 patients in group I, 13 in group II, and 24 in group III. Patients
in group I showed the greatest improvement in Lysholm score among the groups, and
patients in group III had the greatest side-to-side difference by KT-1000 arthrometer.
Tunnel obliquity as measured by the angle between the anteroposterior axis of the
femur and the femoral tunnel in the axial view on MRI was greater (P < .05) and the
angle between the joint line and the graft on the oblique coronal view was less in
group I.
This study showed a significantly lower Lysholm score and more vertical orientation
of the femoral tunnel in the group with residual pivot shift than in the group without
pivot shift. Vertical orientation of the femoral tunnel in the axial plane is closely
related to residual pivot shift without definite anteroposterior laxity. More oblique
positioning of the graft may have advantages in rotational stability, which in turn
increase subjective patient satisfaction.
Level III, diagnostic study of nonconsecutive patients without consistently applied
reference gold standard.