In Vivo Talocrural Joint Contact Mechanics With Functional Ankle Instability

Integration of statistical shape modeling and alternating interpolation-based model tracking technique for measuring knee kinematics in vivo using clinical interleaved bi-plane fluoroscopy

Background

A 2D fluoroscopy/3D model-based registration with statistical shape modeling (SSM)-reconstructed subject-specific bone models will help reduce radiation exposure for 3D kinematic measurements of the knee using clinical alternating bi-plane fluoroscopy systems. The current study aimed to develop such an approach and evaluate in vivo its accuracy and identify the effects of the accuracy of SSM models on the kinematic measurements.

Methods

An alternating interpolation-based model tracking (AIMT) approach with SSM-reconstructed subject-specific bone models was used for measuring 3D knee kinematics from dynamic alternating bi-plane fluoroscopy images. A two-phase optimization scheme was used to reconstruct subject-specific knee models from a CT-based SSM database of 60 knees using one, two, or three pairs of fluoroscopy images. Using the CT-reconstructed model as a benchmark, the performance of the AIMT with SSM-reconstructed models in measuring bone and joint kinematics during dynamic activity was evaluated in terms of mean target registration errors (mmTRE) for registered bone poses and the mean absolute differences (MAD) for each motion component of the joint poses.

Results

The mmTRE of the femur and tibia for one image pair were significantly greater than those for two and three image pairs without significant differences between two and three image pairs. The MAD was 1.16 to 1.22° for rotations and 1.18 to 1.22 mm for translations using one image pair. The corresponding values for two and three image pairs were 0.75 to 0.89° and 0.75 to 0.79 mm; and 0.57 to 0.79° and 0.6 to 0.69 mm, respectively. The MAD values for one image pair were significantly greater than those for two and three image pairs without significant differences between two and three image pairs.

Conclusions

An AIMT approach with SSM-reconstructed models was developed, enabling the registration of interleaved fluoroscopy images and SSM-reconstructed models from more than one asynchronous fluoroscopy image pair. This new approach had sub-millimeter and sub-degree measurement accuracy when using more than one image pair, comparable to the accuracy of CT-based methods. This approach will be helpful for future kinematic measurements of the knee with reduced radiation exposure using 3D fluoroscopy with clinically alternating bi-plane fluoroscopy systems.

Empirical joint contact mechanics: A comprehensive review

Empirical joint contact mechanics measurement (EJCM; e.g. contact area or force, surface velocities) enables critical investigations of the relationship between changing joint mechanics and the impact on surface-to-surface interactions. In orthopedic biomechanics, understanding the changes to cartilage contact mechanics following joint pathology or aging is critical due to its suggested role in the increased risk of osteoarthritis (OA), which might be due to changed kinematics and kinetics that alter the contact patterns within a joint. This article reviews and discusses EJCM approaches that have been applied to articulating joints such that readers across different disciplines will be informed of the various measurement and analysis techniques used in this field. The approaches reviewed include classical measurement approaches (radiographic and sectioning, dye staining, casting, surface proximity, and pressure measurement), stereophotogrammetry/motion analysis, computed tomography (CT), magnetic resonance imaging (MRI), and high-speed videoradiography. Perspectives on approaches to advance this field of EJCM are provided, including the value of considering relative velocity in joints, tractional stress, quantification of joint contact area shape, consideration of normalization techniques, net response (superposition) of multiple input variables, and establishing linkages to regional cartilage health status. EJCM measures continue to provide insights to advance our understanding of cartilage health and degeneration and provide avenues to assess the efficacy and guide future directions of developing interventions (e.g. surgical, biological, rehabilitative) to optimize joint's health and function long term.

Characterization of Changes in Subchondral Bone Tissue Density of the Ankle Joint in Taekwondo Players

Background: It has been found that ankle joint impingement can cause articular cartilage injury, and the change of subchondral bone density and distribution under long-term stress loading can reflect the stress interaction of the articular surface and the difference in bone remodeling degree and predict the location of cartilage injury.

Objective: To investigate the bone density distribution pattern of ankle joint subchondral bone under mechanical stress loading of Taekwondo, the volume proportion of bone tissue with different bone densities, and the distribution characteristics of bone remodeling position.

Study design: A controlled laboratory study.

Methods: Computed tomography data were collected from the feet of 10 normal subjects (control group) and 10 high-level Taekwondo athletes. First, the distribution pattern of the high-density area of the articular surface was determined by computed tomography osteoabsorptiometry and the nine-grid anatomical region localization method. Second, the percentage of bone volume (%BTV) and the distribution trend of bone tissue were measured.

Result: In the present study, it was found that there were high-density areas in the 1st, 2nd, 3rd, 4th, 6th, 7th, and 9th regions of the distal tibia of Taekwondo athletes, and the distribution track was consistent with the high-density areas of the talar dome surface (1st, 2nd, 3rd, 4th, 6th, 7th, and 9th regions). In Taekwondo athletes, the percentage of bone tissue volume in the distal tibia and talus with high and moderate bone density was significantly higher than that in the control group (p < 0.05).

Conclusion: The impact stress, ground reaction force, intra-articular stress, lower limb movement technology, lower limb muscle, and tendon stress caused by Taekwondo lead to special pressure distribution patterns and bone tissue remodeling in the ankle.

Three-Dimensional Subject-Specific Knee Shape Reconstruction with Asynchronous Fluoroscopy Images Using Statistical Shape Modeling

Background and objectives: Statistical shape modeling (SSM) based on computerized tomography (CT) datasets has enabled reasonably accurate reconstructions of subject-specific 3D bone morphology from one or two synchronous radiographs for clinical applications. Increasing the number of radiographic images may increase the reconstruction accuracy, but errors related to the temporal and spatial asynchronization of clinical alternating bi-plane fluoroscopy may also increase. The current study aimed to develop a new approach for subject-specific 3D knee shape reconstruction from multiple asynchronous fluoroscopy images from 2, 4, and 6 X-ray detector views using a CT-based SSM model; and to determine the optimum number of planar images for best accuracy via computer simulations and in vivo experiments.

Methods: A CT-based SSM model of the knee was established from 60 training models in a healthy young Chinese male population. A new two-phase optimization approach for 3D subject-specific model reconstruction from multiple asynchronous clinical fluoroscopy images using the SSM was developed, and its performance was evaluated via computer simulation and in vivo experiments using one, two and three image pairs from an alternating bi-plane fluoroscope.

Results: The computer simulation showed that subject-specific 3D shape reconstruction using three image pairs had the best accuracy with RMSE of 0.52 ± 0.09 and 0.63 ± 0.085 mm for the femur and tibia, respectively. The corresponding values for the in vivo study were 0.64 ± 0.084 and 0.69 ± 0.069 mm, respectively, which was significantly better than those using one image pair (0.81 ± 0.126 and 0.83 ± 0.108 mm). No significant differences existed between using two and three image pairs.

Conclusion: A new two-phase optimization approach was developed for SSM-based 3D subject-specific knee model reconstructions using more than one asynchronous fluoroscopy image pair from widely available alternating bi-plane fluoroscopy systems in clinical settings. A CT-based SSM model of the knee was also developed for a healthy young Chinese male population. The new approach was found to have high mode reconstruction accuracy, and those for both two and three image pairs were much better than for a single image pair. Thus, two image pairs may be used when considering computational costs and radiation dosage. The new approach will be useful for generating patient-specific knee models for clinical applications using multiple asynchronous images from alternating bi-plane fluoroscopy widely available in clinical settings. The current SSM model will serve as a basis for further inclusion of training models with a wider range of sizes and morphological features for broader applications.

Kinematic instability in the joints of flatfoot subjects during walking: A biplanar fluoroscopic study

Abnormal foot kinematics is observed in flatfoot subjects with postural foot deformity. We aimed to investigate joint instability in flatfoot subjects by analyzing the abnormal rotational position and speed of their joints while walking. Five flatfoot subjects participated in our study. Three-dimensional motions of the tibia, talus, calcaneus, navicular, and cuboid were obtained during walking using the biplanar fluoroscopic motion analyses. An anatomical coordinate system was established for each bone. The rotations and ranges of motion (ROMs) of the joints from heel-strike to toe-off were quantified. The relative movements on the articular surfaces were quantified by surface relative velocity vector analysis. The data from flat foot subjects were compared with the data from normal foot subjects in previous studies. The average relative speed on the articular surface of the tibiotalar, subtalar, and calcaneocuboid joints for the flatfoot subjects was significantly higher (p < 0.05) than that for the normal foot subjects. The flatfoot subjects exhibited increased movements toward plantar flexion in the tibiotalar joint, and eversion and external rotations in the talonavicular joint during the stance phase, compared to the normal subjects (p < 0.01). Furthermore, the flatfoot subjects had a significantly larger ROM along with the inversion/eversion rotations (5.6 ± 1.8° vs. 10.7 ± 4.0°) and internal/external rotations (7.1 ± 1.5° vs. 10.5 ± 3.5°) in the tibiotalar joint. The flatfoot subjects demonstrated abnormal kinematics and larger joint movements in multiple joints during the mid-stance and terminal stance phases of walking. This demonstrates their high instability levels.

Ankle Stability and Movement Coordination Impairments: Lateral Ankle Ligament Sprains Revision 2021

This revised clinical practice guideline (CPG) addresses the distinct but related lower extremity impairments of those with a first-time lateral ankle sprain (LAS) and those with chronic ankle instability (CAI). Depending on many factors, impairments may continue following injury. While most individuals experience resolution of symptoms, complaints of instability may continue and are defined as CAI. The aims of the revision were to provide a concise summary of the contemporary evidence since publication of the original guideline and to develop new recommendations or revise previously published recommendations to support evidence-based practice. J Orthop Sports Phys Ther 2021;51(4):CPG1-CPG80. doi:10.2519/jospt.2021.0302.

Assignment of local coordinate systems and methods to calculate tibiotalar and subtalar kinematics: A systematic review

The introduction of biplane fluoroscopy has created the ability to evaluate in vivo motion, enabling six degree-of-freedom measurement of the tibiotalar and subtalar joints. Although the International Society of Biomechanics defines a standard method of assigning local coordinate systems for the ankle joint complex, standards for the tibiotalar and subtalar joints are lacking. The objective of this systematic review was to summarize and appraise the existing literature that (1) defined coordinate systems for the tibia, talus, and/or calcaneus or (2) assigned kinematic definitions for the tibiotalar and/or subtalar joints. A systematic literature search was developed with search results limited to English Language from 2006 through 2020. Articles were screened by two independent reviewers based on title and abstract. Methodological quality was evaluated using a modified assessment tool. Following screening, 52 articles were identified as having met inclusion criteria. Methodological assessment of these articles varied in quality from 61 to 97. Included articles adopted primary methods for defining coordinate systems that included: (1) anatomical coordinate system (ACS) based on individual bone landmarks and/or geometric shapes, (2) orthogonal principal axes, and (3) interactive closest point (ICP) registration. Common methods for calculating kinematics included: (1) joint coordinate system (JCS) to calculate rotation and translation, (2) Cardan/Euler sequences, and (3) inclination and deviation angles for helical angles. The methods each have strengths and weaknesses. This summarized knowledge should provide the basis for the foot and ankle biomechanics community to create an accepted standard for calculating and reporting tibiotalar and subtalar kinematics.

Lateral Ankle Sprains and Their Association with Physical Function in Young Soccer Players

Purpose

Lateral ankle sprain (LAS) in childhood can result in lateral malleolus avulsion fractures; additionally, bone nonunion may occur. Physical maturity relates to the development of bone morphology and physical functionality. It is unknown how changes in physical functionality attributable to physical maturity affect young soccer players with abnormal lateral malleolus (ALM) morphology. Hence, the present study aimed to investigate the bone morphology of the lateral malleolus in young soccer players and to examine its relationship with physical functionality at different maturity levels.

Subjects and Methods

Two hundred and ninety young soccer players aged 6–15 years were included. The presence of ALM was assessed using ultrasonography. The subjects were allocated to three groups based on physical maturity (Pre-, Mid-, and Post-peak height velocity age [PHVA]). The prevalence of ALM and the relationship between ALM and physical maturity were examined for body composition, foot pressure distribution, foot alignment, ankle mobility, and single-leg balance.

Results

The prevalence of ALM was 17.6%. For physical maturity, the post-PHVA group showed a decrease in ankle dorsiflexion and eversion and an increase in one-leg hop distance compared to the Pre-PHVA group (P < 0.05). In the ALM group, the center of pressure during heel raising was distributed laterally in the Post-PHVA (P < 0.01), and the weight-bearing dorsiflexion angle was decreased in the Mid- and Post-PHVA (P < 0.05).

Conclusion

In the Post-PHVA young soccer players, decreased ankle dorsiflexion and eversion and increased one-leg hop distance were observed. The ALM group exhibited lateral loading during heel raising in the Post-PHVA group and decreased weight-bearing ankle dorsiflexion angle in the Mid- and Post-PHVA groups. The findings indicate the importance of secondary prevention of LAS and ultrasonography. Prospective studies of LAS in young athletes are required in the future.

Contact patterns in the ankle joint after lateral ligamentous injury during internal rotation: A computational study

Lateral ankle instability, resulting from the inability of ankle ligaments to heal after injury, is believed to cause a change in the articular contact mechanics that may promote cartilage degeneration. Considering that lateral ligaments' insufficiency has been related to rotational instability of the talus, and that few studies have addressed the contact mechanics under this condition, the aim of this work was to evaluate if a purely rotational ankle instability could cause non-physiological changes in contact pressures in the ankle joint cartilages using the finite element method. A finite element model of a healthy ankle joint, including bones, cartilages and nine ligaments, was developed. Pure internal talus rotations of 3.67°, 9.6° and 13.43°, measured experimentally for three ligamentous configurations, were applied. The ligamentous configurations consisted in a healthy condition, an injured condition in which the anterior talofibular ligament was cut, and an injured condition in which the anterior talofibular and calcaneofibular ligaments were cut. For all simulations, the contact areas and maximum contact pressures were evaluated for each cartilage. The results showed not only an increase of the maximum contact pressures in the ankle cartilages, but also novel contact regions at the anteromedial and posterolateral sections of the talar cartilage with increasing internal rotation. The anteromedial and posterolateral contact regions observed due to pathological internal rotations of the talus are a computational evidence that supports the link between a pure rotational instability and the pattern of pathological cartilaginous load seen in patients with long-term lateral chronic ankle instability.

Decreased perceived ankle and knee joint health in individuals with perceived chronic ankle instability

PURPOSE

Abnormal movement patterns and neuromuscular impairments at the ankle are thought to contribute to ankle joint degeneration in those with chronic ankle instability. However, these impairments are not confided to the ankle; rather, proximal neuromuscular deficiencies at the knee and aberrant movement patterns, thought to be responsible for reductions in knee joint health, have also been identified. While neuromuscular impairments and self-reported functional limitations have been examined in those with chronic ankle instability, patient-generated symptoms associated with joint health of the ankle and knee have not been investigated. Therefore, the purpose was to compare perceived ankle and knee joint health in individuals with and without chronic ankle instability.

METHODS

The Ankle Osteoarthritis Scale and the Knee Injury and Osteoarthritis Outcome Score assessed region-specific ankle and knee joint health.

RESULTS

Participants with chronic ankle instability reported more ankle pain (P < 0.001) and disability (P < 0.001) than the control group. Chronic ankle instability individuals also reported worse knee joint health (P < 0.05).

CONCLUSIONS

The increased symptomology associated with decreased ankle joint health further supports information demonstrating joint degeneration in young adults with chronic ankle instability. The decreased perceived knee joint health provides preliminary evidence of the negative impact proximal neuromuscular impairments associated with chronic ankle instability that may have on joints other than the ankle. Assessing subjective ankle and knee joint function can guide clinicians in developing individualized rehabilitation by providing them with an understanding if a patient presenting with chronic ankle instability suffers from symptoms arising from more than just the ankle.

LEVEL OF EVIDENCE

Case-control, Level III.

Evaluation of the Talar Cartilage in Chronic Lateral Ankle Instability with Lateral Ligament Injury Using Biochemical T2* Mapping: Correlation with Clinical Symptoms

RATIONALE AND OBJECTIVES

This study aims to quantitatively compare T2* measurements of the talar cartilage between chronic lateral ankle instability (LAI) patients with lateral ligament injury and healthy volunteers, and to assess the association of T2* value with American Orthopedic Foot and Ankle Society (AOFAS) score.

MATERIALS AND METHODS

Nineteen consecutive patients with chronic LAI (LAI group) and 19 healthy individuals (control group) were enrolled. Biochemical magnetic resonance examination of the ankle was performed in all participants using three-dimensional gradient-echo T2* mapping. Total talar cartilage was divided into six subcompartments, including medial anterior (MA), central medial, medial posterior, lateral anterior, central lateral (LC), and lateral posterior regions. T2* values of respective cartilage areas were measured and compared between the two groups using Student t test. AOFAS scoring was performed for clinical evaluation. Then, the association of T2* value with AOFAS score was evaluated by Pearson correlation.

RESULTS

The T2* values of total talar cartilage, as well as MA and LC cartilage compartments, in the chronic LAI group were significantly higher than control values (P < .001, P = .039, and P = .014, respectively). Furthermore, the T2* value of MA in the chronic LAI group was negatively correlated with AOFAS score (r = -0.8089, P < .001).

CONCLUSIONS

Chronic LAI with lateral ligament injury may have a causal connection with early cartilage degeneration in the ankle joint, especially in MA and LC cartilage compartments, as assessed by quantitative T2* measurements. The clinical score correlates highly with T2* value of the MA cartilage compartment, indicating that MA may be the principal cartilage area conferring clinical symptoms.

A model-based tracking method for measuring 3D dynamic joint motion using an alternating biplane x-ray imaging system

PURPOSES

To propose a new model-based tracking method for measuring three-dimensional (3D) dynamic joint kinematics using a clinical alternating biplane x-ray imaging system; and to quantify in vitro its errors in measuring ankle and knee motions at different motion speeds.

METHODS

A new model-based tracking method based on motion component partition and interpolation (MCPI) was developed for measuring 3D dynamic joint kinematics based on a clinical alternating biplane x-ray imaging system. Two detectors of the biplane imaging system placed perpendicular to each other were operated to collect alternating fluoroscopic images of the targeted joint during tasks. The CT data of the joint were also acquired for the reconstruction of volumetric and surface models of each of the associated bones. The CT-based models of the bones were first registered to the alternating images using a model-to-single-plane fluoroscopic image registration method, and the resulting bone poses were then refined using a two-level optimization with motion component partition and model vertex trajectory interpolation. The MCPI method was evaluated in vitro for measurement errors for an ankle and a knee specimen moving at different speeds against a standard reference provided by a highly accurate motion capture system. The positional and rotational errors of the measured bone poses were quantified in terms of the bias, precision, and root-mean-squared errors (RMSE), as well as the mean target registration error (mTRE), a final mTRE less than 2.5 mm indicating a successful registration.

RESULTS

The new method was found to have RMSE of bone pose measurements of less than 0.18 mm for translations and 0.72° for rotations for the ankle, and 0.33 mm and 0.74° for the knee with a high successful registration rate (>97%), and did not appear to be affected by joint motion speeds. Given the same alternating fluoroscopic images, the MCPI method outperformed the typical biplane analysis method assuming zero time offset between the two fluoroscopic views. The differences in performance between the methods were increased with increased joint motion speed. With the accurate bone pose data, the new method enabled talocrural, subtalar, and tibiofemoral kinematics measurements with submillimeter and subdegree accuracy, except for an RMSE of 1.04° for the internal/external rotation of the talocrural joint.

CONCLUSIONS

A new model-based tracking method based on MCPI has been developed for measuring dynamic joint motions using an alternating biplane x-ray imaging system widely available in medical centers. The MCPI method has been demonstrated in vitro to be highly accurate in determining the 3D kinematics of the bones of both the ankle joint complex and the knee. The current results suggest that the MCPI method would be an effective approach for measuring in vivo 3D kinematics of dynamic joint motion in a clinical setting equipped with an alternating biplane x-ray imaging system.

Valgus Ankle Degenerative Arthritis with an Isolated Deltoid Insufficiency and Tibial Varus: A Case Report

We report a case of valgus ankle degenerative arthritis due to chronic isolated deltoid insufficiency combined with tibial varus that was treated successfully with ankle joint preserving surgery. A 63-year-old male complained of right lateral ankle pain with 10 minutes of maximal pain-free walking time. The assessed American Orthopaedic Foot and Ankle ankle-hindfoot scale score was 33 points. The ankle joint showed 18° of valgus deformity with 6° of tibia varus. Medial displacement calcaneal osteotomy, supramalleolar open wedge osteotomy, and deltoid ligament imbrication were performed. At the 2-year follow-up examination, the ankle joint showed 10° of valgus and the tibial plafond showed flattening. The hindfoot showed 7° of valgus. He could run for 2 hours on the treadmill without pain. The American Orthopaedic Foot and Ankle ankle-hindfoot scale score was 90 points. In conclusion, valgus ankle degenerative arthritis with isolated deltoid insufficiency and tibial varus could be treated successfully with realignment using a double osteotomy and additional deltoid imbrication.