Six DOF in vivo kinematics of the ankle joint complex: Application of a combined dual‐orthogonal fluoroscopic and magnetic resonance imaging technique

Abstract

Accurate knowledge of in vivo ankle joint complex (AJC) biomechanics is critical for understanding AJC disease states and for improvement of surgical treatments. This study investigated 6 degrees-of-freedom (DOF) in vivo kinematics of the human AJC using a combined dual-orthogonal fluoroscopic and magnetic resonance imaging (MRI) technique. Five healthy ankles of living subjects were studied during three in vivo activities of the foot, including maximum plantarflexion and dorsiflexion, maximum supination and pronation, and three weight-bearing positions in simulated stance phases of walking. A three-dimensional (3D) computer model of the AJC (including tibia, fibula, talus, and calcaneus) was constructed using 3D MR images of the foot. The in vivo AJC position at each selected position of the foot was captured using two orthogonally positioned fluoroscopes. In vivo AJC motion could then be reproduced by coupling the orthogonal images with the 3D AJC model in a virtual dual-orthogonal fluoroscopic system. From maximum dorsiflexion to plantarflexion, the arc of motion of the talocrural joint (47.5 AE 2.28) was significantly larger than that of the subtalar joint (3.1 AE 6.88). Both joints showed similar degrees of internalexternal and inversion-eversion rotation. From maximum supination to pronation, all rotations and translations of the subtalar joint were significantly larger than those of the talocrural joint. From heel strike to midstance, the plantarflexion contribution from the talocrural joint (9.1 AE 5.38) was significantly larger than that of the subtalar joint (À0.9 AE 1.28). From midstance to toe off, internal rotation and inversion of the subtalar joint (12.3 AE 8.38 and À10.7 AE 3.88, respectively) were significantly larger than those of the talocrural joint (À1.6 AE 5.98 and À1.7 AE 2.78). Strong kinematic coupling between the talocrural and subtalar joints was observed during in vivo AJC activities. The contribution of the talocrural joint to active dorsi-plantarflexion was higher than that of the subtalar joint, whereas the contribution of the subtalar joint to active supination-pronation was higher than that of the talocrural joint. In addition, the talocrural joint demonstrated larger motion during the early part of stance phase while the subtalar joint contributes more motion during the later part of stance phase. The results add quantitative data to an in vivo database of normals that can be used in clinical diagnosis, treatment, and evaluation of the AJC after injuries. ß

Changes in talocrural and subtalar joint kinematics of barefoot versus shod forefoot landing

“…The movement pattern of the talocrural joint was consistent with previous in vivo fluoroscopic studies [14,17]. On the contrary, subtalar joint eversion, after heel contact, was reduced in the shod condition.…”

“…In recent years, radiographic shape-matching techniques (i.e., 3 dimensional 2 dimensional (3D-2D) model-image registration) have been applied to the foot and ankle [14,15] to overcome the methodological difficulties associated with motion analysis due to skin movement artifact. Shape-matching techniques are advantageous, as they provide detailed information regarding in vivo joint kinematics with a less invasive methodology.…”

“…Shape-matching techniques are advantageous, as they provide detailed information regarding in vivo joint kinematics with a less invasive methodology. Thus, this technique may be used to quantify 3D kinematics following total ankle arthroplasties [16,17] and in healthy ankles during dorsiflexion-plantarflexion activities [15] and simulated static gait positions [14]. This method also overcomes the problem of impaired footwear function by visualizing the actual foot bones.…”

Multi-Rigid Image Segmentation and Registration for the Analysis of Joint Motion From Three-Dimensional Magnetic Resonance Imaging

“…Externally mounted retro-reflective markers may also be used [4], but these methods are susceptible to skin-motion artifact. Because of these limitations, various imaging modalities, including computed tomography (CT) [11,31], MRI [3,32,33], and biplane fluoroscopy [7,8] will likely play increasingly important roles in foot kinematic studies. As such, it is necessary to have robust and accurate software for segmentation and registration that minimizes user interaction time.…”

“…(While the examples discussed in this paper are foot specific, the principles apply to any joint in the body.) Methods include X-ray stereophotogrammetry [1,2], time sequence magnetic resonance imaging (MRI) [3], retro-reflective markers, placed either on the skin [4] or on bone pins [5], or recently, single [6] and biplane fluoroscopy [7,8]. Some of these methods involve ionizing radiation (X-ray stereophotogrammetry and fluoroscopy) or are highly invasive (X-ray stereophotogrammetry and bone pins), leaving time sequence MRI, and skin mounted markers as the safest methods.…”