A deficient anterior cruciate ligament does not lead to quadriceps avoidance gait

108

Reduced knee flexion is a logical gait adaptation for individuals with patellofemoral pain (PFP) to lessen the patellofemoral joint reaction force and minimise pain during stair ambulation. This gait adaptation may be related to the co‐ordination of individual vasti components. Purpose: This study investigated the amount of stance‐phase knee flexion in individuals with (n = 48) and without (n = 18) PFP using a cross‐sectional design. The relationship between stance‐phase knee flexion and onset timing of individual vasti activity was also examined. Method: Stance‐phase knee flexion was measured in 2‐dimensions using a PEAK movement analysis system during stair ascent and descent. Individuals with PFP were separated into those with synchronous onset of the EMG activity of vastus medialis obliquus (VMO) and vastus lateralis (VL), and those where the onset of VMO EMG activity was delayed relative to the VL. Results: The amount of knee flexion at heel‐strike and peak was less in the individuals with PFP compared with the healthy controls. In addition, there were trends towards individuals with PFP who had a delayed EMG onset of VL having reduced knee flexion during stair descent compared with PFP individuals with simultaneous vasti onsets and the control participants. Conclusion: These results indicate that the amount of stance‐phase knee flexion is lower in individuals with PFP and that this may be related to onset timing of the vasti. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.

Section: Is Reduced Stance-phnse Knee Jlrxion Associated Hyth Patellomentioning

confidence: 99%

Knee flexion during stair ambulation is altered in individuals with patellofemoral pain

Crossley

Cowan

Bennell

et al. 2004

108

“…Most studies of individuals after ACL rupture identify adaptations in knee motions and moments and then infer how the adaptations influence tibial translation. For example, subjects with ACL injury show a more flexed knee at midstance, [2,22] and this has been hypothesized to occur because obligatory quadriceps activity in this phase of gait, in combination with a more extended knee, can cause anterior tibial translation [17]. More direct measures of tibial translation have been performed in vitro using robotic force sensors and in vivo using markers rigidly attached to bone with intercortical bone pins.…”

Section: Tl Chinieleit~ski El Ul I Journul Of' Orthopueclic Rrsrumentioning

confidence: 99%

Evidence for differential control of tibial position in perturbed unilateral stance after acute ACL rupture

Chmielewski¹,

Ramsey²,

Snyder‐Mackler³

2005

Functional outcomes in anterior cruciate ligament-deficient "potential copers" and "non-copers" may be related to their knee stabilization strategies. Therefore, the purpose of this study was to differentiate dynamic knee stabilization strategies of potential copers and non-copers through analysis of sagittal plane knee angle and tibia position during disturbed and undisturbed unilateral standing. Ten uninjured potential coper and non-coper subjects stood in unilateral stance on a platform that translated anteriorly, posteriorly and laterally. Knee angle and tibia position with reference to the femur were calculated before and after platform movement. During perturbation trials, potential copers maintained kinematics that were similar to uninjured subjects across conditions. Conversely, non-copers stood with greater knee flexion than uninjured subjects and a tibia position that was more posterior than the other groups. Both non-copers and potential copers demonstrated small changes in tibia position following platform movement, but direction of movement was not similar. The similarities between the knee kinematics of potential copers and uninjured subjects suggest that potential copers compensated well from their injury by utilizing analogous dynamic knee stabilization strategies. In comparison to the other groups, by keeping the knee in greater flexion and the tibia in a more posterior position, non-copers appear to constrain the tibia in response to a challenging task, which is consistent with a "stiffening strategy".Based on the poor functional outcomes of non-copers, a stiffening strategy does not lead to dynamic knee stability, and the strategy may increase compressive forces which could contribute to or exacerbate articular cartilage degeneration.

“…3 Gait analysis can also be used to determine dynamic changes in the knee by calculating changes in joint moments during gait. [4][5][6] Both of these assessment techniques, however, measure the relative movement between the bones and do not evaluate soft tissue movement. The meniscus is a critical component of the knee joint, distributing axial load from the femoral condyles on the tibial plateau.…”

Section: Introductionmentioning

confidence: 99%

MRI analysis of in vivo meniscal and tibiofemoral kinematics in ACL‐deficient and normal knees

Shefelbine

Benjamin

Lee

et al. 2006

108

The objectives of this study were to analyze simultaneously meniscal and tibiofemoral kinematics in healthy volunteers and anterior cruciate ligament (ACL)-deficient patients under axial load-bearing conditions using magnetic resonance imaging (MRI). Ten healthy volunteers and eight ACL-deficient patients were examined with a high-field, closed MRI system. For each group, both knees were imaged at full extension and partial flexion ($458) with a 125N compressive load applied to the foot. Anteroposterior and medial/lateral femoral and meniscal translations were analyzed following three-dimensional, landmark-matching registration. Interobserver and intraobserver reproducibilities were less than 0.8 mm for femoral translation for image processing and data analysis. The position of the femur relative to the tibia in the ACL-deficient knee was 2.6 mm posterior to that of the contralateral, normal knee at extension. During flexion from 08 to 458, the femur in ACL-deficient knees translated 4.3 mm anteriorly, whereas no significant translation occurred in uninjured knees. The contact area centroid on the tibia in ACL-deficient knees at extension was posterior to that of uninjured knees. Consequently, significantly less posterior translation of the contact centroid occurred in the medial tibial condyle in ACL-deficient knees during flexion. Meniscal translation, however, was nearly the same in both groups. Axial loadbearing MRI is a noninvasive and reproducible method for evaluating tibiofemoral and meniscal kinematics. The results demonstrated that ACL deficiency led to significant changes in bone kinematics, but negligible changes in the movement of the menisci. These results help explain the increased risk of meniscal tears and osteoarthritis in chronic ACL deficient knees. ß