Abstract
PurposeQuantifying the effects of anterior cruciate ligament (ACL) deficiency on knee joint laxity is fundamental for understanding the outcomes of its reconstruction techniques. The general aim of this study was to determine intra-operatively the main modifications in knee laxity before and after standard isolated intra-articular and additional extra-articular anterolateral reinforcement. Our main hypothesis was that laxity abnormalities, particularly axial rotation, can still result from these ACL reconstruction techniques.MethodsThirty-two patients with primary ACL deficiency were analysed by a navigation system immediately before and after each of the two reconstructions. Laxity measurements in terms of knee translations and rotations were taken during the anteroposterior drawer test, with internal–external rotation at 20° and 90° of flexion, and varus–valgus and pivot-shift tests. All these laxity measures were also taken originally from the contralateral healthy knee.ResultsWith respect to the contralateral healthy knee, in the ACL-deficient knee significantly increased laxity (expressed in %) was found in the medial compared with that of the lateral compartment, respectively, 115 and 68 % in the drawer test at 20° flexion, and 55 and 46 % at 90° flexion. In the medial compartment, a significant 35 % increment was also observed for the coupled tibial anteroposterior translation during axial knee rotation at 20° of flexion. After isolated intra-articular reconstruction, normal values of anteroposterior laxity were found restored in the pivot-shift and drawer tests in the lateral compartment, but not fully in the medial compartment. After the reinforcement, laxity in the medial compartment was also found restored in the axial rotation test at 20° flexion.ConclusionIn ACL reconstruction, with respect to the contralateral knee, intra-articular plus additional anterolateral reinforcement procedures do not restore normal joint laxity. This combined procedure over-constrained the lateral compartment, while excessive laxity still persists at the medial one.Level of evidenceIII.
Highlights
Over the last 30 years, advancements in anterior cruciate ligament (ACL) reconstruction techniques have enabled less invasive knee surgery and a more rapid recovery for the patients
During the anteroposterior drawer test, in contralateral healthy knee (CHK) the anteroposterior laxity was higher at 20° than at 90° (p < 0.00), and in every single knee that in the lateral compartment was more than twice the value of that in the medial compartment (Fig. 2; Table 2)
At 20° flexion, laxity in the medial compartment at CHK was somehow restored with IAR, but this result deteriorated after IAR + ALR; in the lateral compartment, CHK laxity (13 mm) was already over-constrained with IAR (11 mm, p = 0.025) and even more with IAR + ALR (9 mm, p < 0.00)
Summary
Over the last 30 years, advancements in anterior cruciate ligament (ACL) reconstruction techniques have enabled less invasive knee surgery and a more rapid recovery for the patients. Long-term follow-up studies of intra- and additional extra-articular reconstruction have not shown improvement in reducing these degenerative changes [49, 54, 62]. Modern measurement systems, such as electromagnetic or inertial motion units or digital image-based motion analysis, claim to provide in vivo knee motion for joint laxity evaluation, but these non-invasive systems have not yet been fully validated for clinical applications [3, 48]. Surgical navigation systems are able to perform reliable measurements of joint laxity at the ACL-injured knee [23, 48], the corresponding original pre-injury data are obviously unknown. There are no data about normal joint laxity derived from bone tracking in vivo in healthy knees
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