Elsevier

Gait & Posture

Volume 38, Issue 4, September 2013, Pages 712-716
Gait & Posture

Kinematic characteristics of the tibiofemoral joint during a step-up activity

https://doi.org/10.1016/j.gaitpost.2013.03.004Get rights and content

Highlights

  • The tibial contact points moved anteriorly during the step-up, similar to TEA, but not GCA

  • Medial-pivoting was not observed during step-up activity

  • Selection of coordinate systems changed knee joint kinematics description dramatically

Abstract

The step-up activity (stair-ascending) is an important daily function of the knee. This study aimed to investigate the articular cartilage contact kinematics on both tibial and femoral cartilage surfaces and describe the femoral condylar motion using the transepicondylar axis (TEA) and the geometric center axis (GCA) during a step-up activity. Twenty-one healthy subjects were included and their knee joint models were reconstructed using MR images. A single-stair step-up activity was imaged using a dual-fluoroscopic imaging system. Three-dimensional knee joint contact points were determined and projected onto the tibial plateau and femoral condylar surfaces. The contact points on the medial and lateral tibial plateau moved anteriorly (by 13.5 ± 3.2 and 10.7 ± 5.0 mm, respectively, p > 0.05) with knee extension. The contact points on the medial and lateral femoral condyle moved from the posterior to the anterior portion (by 32.2 ± 4.9 mm and 25.5 ± 4.2 mm, respectively, p < 0.05) and were located on the inner half of the femoral cartilage throughout the activity. The data on articular contact kinematics and the femoral condylar motion described using the TEA and GCA indicated that the medial and lateral compartments had similar motion patterns during the step-up activity. The knee does not demonstrate a medial-pivoting motion character during the step-up activity. The data may provide insight to contemporary TKA development.

Introduction

Step-up (stair ascending) is one of the most important daily activities, and has been adopted as a closed-kinetic chain exercise in various lower extremity rehabilitation protocols [1], [2]. During a step-up activity, a large knee joint moment could be generated together with a quadriceps-hamstring co-contraction to help stabilize the knee joint [3], [4]. Therefore, a thorough understanding of the knee joint biomechanics during step-up activity is important for optimizing the rehabilitation protocol to enhance its efficacy in treatment of different pathologies of the knee such as osteoarthritis (OA), ACL reconstruction and total knee arthroplasty (TKA) [3], [5].

Few studies have quantitatively reported on the knee joint kinematics during the step-up motion [6], [7], [8]. For example, Gao et al. [9] used motion analysis method to measure the kinematics of ACL deficient and ACL reconstructed knees. Kozanek et al. [7] compared the knee kinematics during the step-up exercise between ACL deficient and intact contralateral knees using a combined dual-fluoroscopic imaging system (DFIS) and MRI-based model. In a recent study by Moro-oka et al. [10], the articular contact patterns of the knee were approximated using the distance mapping between the tibiofemoral articular cartilage surfaces. While these studies have greatly improved our knowledge on knee kinematics during the step-up activities, the different experimental designs and coordinate system selections made it difficult to obtain a systematic understanding of the knee joint kinematics behavior during the step-up activity.

Therefore, the purpose of this study was to measure the kinematic features of the tibiofemoral joint during the step-up activity using the combined DFIS and MRI technique. Specifically, we measured the tibiofemoral articular cartilage contact point locations during a dynamic step-up motion. Furthermore, we measured the femoral condylar motions using two well-known flexion axes, i.e., the transepicondylar axis (TEA) and the geometry center axis (GCA), and calculated the axial tibial rotation based on these two flexion axes [11].

Section snippets

Methods

Twenty-one healthy knees without any history of surgery from 21 subjects were recruited in this study (age, 34.6 ± 10.4 years; gender, 14 males and 7 females; body height, 1.8 ± 0.1 m; body weight, 80.9 ± 18.1 kg) with informed consent. The testing protocol was approved by our institutional review board. A 3-Tesla magnetic resonance machine (MAGNETOM Trio, Siemens, Malvern, PA) was used to scan the knee joint in the sagittal plane with a double-echo water excitation sequence (thickness: 1 mm,

Results

The flexion angles ranged from 54.4 ± 7.1° at initial contact to full extension at the end of the step-up activity. The average time for the activity was 0.8 ± 0.2 s.

Discussion

This study investigated the in vivo articular cartilage contact kinematics on both tibial plateau and femoral condyle surfaces during a functional step-up (stair ascending) activity. The femoral condylar motions were also measured using the TEA and GCA. In general, both medial and lateral contact points moved anteriorly on the tibial articular surfaces along the step-up motion path. The total excursion of the articular contact points was similar on the medial and lateral tibial surfaces.

Conflicts of Interest

The authors have no financial affiliation or involvement with any commercial organization that has a direct financial interest in this manuscript.

Acknowledgements

The authors would like to gratefully acknowledge the financial support of the National Institute of Health (R01 AR055612) and the Department of Orthopaedic Surgery at Massachusetts General Hospital.

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