Elsevier

Gait & Posture

Volume 36, Issue 1, May 2012, Pages 56-60
Gait & Posture

Gait analysis post anterior cruciate ligament reconstruction: Knee osteoarthritis perspective

https://doi.org/10.1016/j.gaitpost.2012.01.003Get rights and content

Abstract

Individuals with anterior cruciate ligament (ACL) reconstruction are at increased risk to develop knee osteoarthritis (OA). Gait analysis describing kinetics of the lower extremity during walking and stair use (stair ascent and stair descent) can provide insight to everyday dynamic knee joint loading. In this study, we compared lower extremity gait patterns of those with ACL reconstruction (>1 year) to a control group. Fifteen ACL reconstructed individuals and 17 healthy controls participated in this study. Knee extensor and flexor strength were assessed. Using inverse dynamics, lower extremity moments were calculated during the stance phase of walking and during two steps of stair ascent and descent. Univariate ANOVA was used to test for main effects between (1) injured leg and control group and (2) non-injured leg and control group. Student paired t-tests were used to determine differences between the injured and non-injured leg. Those with ACL reconstruction exhibited reduced initial knee flexion angles during stair descent, reduced knee extension moments during stair descent and stair ascent (second step), and increased hip extension moments during stair ascent (second step) and walking as compared to controls. Knee flexor strength was significantly reduced in the ACL group, but no differences were found in knee extensor strength. No kinematic or kinetic differences were observed between the injured and non-injured leg of the ACL group. Walking and stair ambulation highlight altered joint loading in those with ACL reconstruction surgery. Individuals appeared to compensate for lower knee extension moments by increasing hip extension moments. Furthermore, the load distribution on the articular cartilage is likely shifted as evidenced by reduced knee flexion angles in the ACL reconstructed leg.

Highlights

► Analysis of stair use and walking in individuals post-ACL reconstruction (>1 year). ► Walking and stair use highlight altered joint loading post-ACL reconstruction. ► Reduced knee extension moments at least 1 year post-ACL reconstruction. ► Increased hip extension moments at least 1 year post-ACL reconstruction.

Introduction

Anterior cruciate ligament (ACL) injuries are among the most common musculoskeletal injuries, occurring frequently in young adults, especially women. Individuals younger than 30 years old sustain ACL ruptures more often as compared to the general population [1], [2]. ACL ruptures are often concurrent with meniscal injuries [2] and where combined injury has occurred, 48% of cases have evidence of knee osteoarthritis (OA) within 5–20 years after initial ACL injury [2], [3]. Therefore, individuals between 35 and 40 years old are at increased risk of knee OA following ACL rupture [1].

Structural changes associated with ACL injury combined with long-term changes in dynamic loading contribute to the development of knee OA [2]. As a measuring tool, gait analysis is considered a practical and reliable technique to indirectly assess dynamic loads on the lower extremity [4]. Investigating lower extremity kinetics during walking and stair negotiation can provide insight into everyday repetitive loads placed on the knee joint.

Arguably, external knee varus moments have the greatest clinical consequence when considering potential knee OA risk factors. Knee varus moments are associated with medial compression, the compartment most often affected with OA. Miyazaki et al. [5] established that the risk of knee OA progression increased by a factor of 6 with each 1% increase in knee varus moments. Attention has also focused on the role of the hip abductors in protecting against knee OA. Impaired hip abduction moment generation causes contralateral pelvis drop, increasing knee varus moments and medial compression [6], [7]. Hooper et al. [8] observed no differences in knee varus moments while walking or using the stairs when comparing the injured and non-injured leg one year post-ACL reconstruction. However, Butler et al. [9] observed 21% greater knee varus moments during walking in individuals five years following ACL reconstruction when compared to a control group. Increased knee varus moments may not be present within the first year of ACL rupture, but medial knee loading may increase as time progresses. Further study is required to assess whether dynamic knee joint loading is greater for individuals post-ACL surgery during walking and stair ambulation.

Sagittal lower extremity kinetic accommodations at the knee [8], [10], [11] and hip [8], [11], [12] have been reported following ACL reconstruction. Individuals 6–12 months post-ACL reconstruction have altered walking patterns as compared to controls, including reduced knee flexion angles at mid-stance [8], [11] and reduced knee extension moments during early stance [10], [11]. These gait adaptations may lead to degenerative changes in the articular cartilage by altering the loading patterns on the knee joint. Decreased knee flexion angles and knee extension moments have been associated with quadriceps weakness up to one year post-ACL surgery [13], [14]. Large cross-sectional studies have established strong relationships between quadriceps weakness and the onset of knee OA [15], [16]. Persistent quadriceps weakness developed through arthrogenic inhibition leads to altered kinetics and kinematics after knee injury [17]. Despite ACL reconstruction and aggressive rehabilitation regimes, weakness in quadriceps musculature exists up to one year post-ACL reconstruction surgery [18]. Theoretically, weak quadriceps musculature reduces the ability to generate the necessary force to provide efficient eccentric control during the loading phase of gait [17]. It has yet to be determined if quadriceps weakness along with reduced knee extension moments and knee flexion angles persist long-term (greater than one year after ACL reconstruction).

The purpose of this study was to analyze the gait of those with ACL reconstruction and a comparable healthy group during stair ascent, stair descent, and level walking. The primary focus was to determine if factors associated with the development and/or progression of knee OA were observed in the ACL reconstructed limb when compared to the non-injured limb and healthy counterparts. We hypothesized that the ACL reconstructed leg would display: (1) increased external knee varus moments, (2) reduced knee extensor strength, (3) reduced knee flexion angles, and (4) reduced knee extension moments when compared to the non-injured limb and control group.

Section snippets

Participants

Individuals >1 year from unilateral ACL reconstruction and healthy controls between 18 and 35 years old were recruited from a university setting. Exclusion criteria included history of any other musculoskeletal or neurological conditions precluding safe walking and stair negotiation. Control participants were excluded if they had a previous knee ligament injury or surgery. Our study aimed to match participants (i.e., age and sex) at group level. This study was approved by the Institutional

Methods

A 10 m walkway and a three-step staircase (step height 18.5 cm, tread depth 29.5 cm) were used. Kinematic data were collected using an 8-camera, three-dimensional motion analysis system (Vicon Nexus, Los Angeles, CA). Kinetic data were recorded using two portable force platforms positioned on the first and second step of the stairs and one in-ground force platform for level walking (AMTI, Watertown, MA). Kinematic data were collected at a sampling rate of 160 Hz, while force platform data were

Results

Overall, 19 people with unilateral ACL reconstruction and 17 healthy controls were examined. Due to equipment malfunction and numerical outliers, a subset of the cohort are presented for stair analysis (ACL = 14; control = 13) and walking analysis (ACL = 15; control = 17). There were no differences between the ACL group and controls for age, height, and body mass (Table 1). Furthermore, no differences in Tegner scores were found between the groups, verifying that all post-ACL individuals had returned

Discussion

This study aimed to determine if biomechanical parameters associated with the development and/or progression of knee OA existed >1 year post-ACL reconstruction. Knee injuries, including ACL ruptures, increase the risk for early-onset knee OA by 10-fold as compared to the general, uninjured population [20]. Focusing on repetitive movements such as stair use and walking in a post-ACL reconstruction cohort provides a good model to investigate the early onset of knee OA pathogenesis.

Contrary to our

Conflict of interest

The authors declare that there is no conflict of interest.

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