Human Ankle Research Articles

Mass Spectrometry Characterization of the Human Ankle and Hindfoot Fracture Microenvironment in Young and Aged Subjects

Mass Spectrometry Characterization of the Human Ankle and Hindfoot Fracture Microenvironment in Young and Aged Subjects

A lightweight semi-active ankle exoskeleton utilized NiTiCu-based shape memory alloys for energy storage.

Nowadays, exoskeletons have a place in many fields, such as industrial production, medical rehabilitation, and military. However, there are still many shortcomings in the existing exoskeleton, such as heavyweight and complex structures for active exoskeleton. The driving ability of passive exoskeletons is limited. To reduce the energy consumption of wearers, based on the characteristics of the semi-active ankle exoskeleton, this paper proposes to use NiTiCu-based shape memory alloys (SMA) as the energy storage source to improve the power density. Compared to NiTi-based SMA, the phase transformation process of NiTiCu-based SMA is more rapid, which can solve the response delay problem to a certain extent. The ankle exoskeleton uses SMA deformation to compress the bias spring. When the human ankle joint needs auxiliary torque, the SMA releases the energy stored by the bias spring and transfers the energy to the ankle exoskeleton to achieve the effect of assisting the human ankle joint. During the assistance process, a control system based on the SMA mathematical model is constructed. The above-mentioned ideas provide a new approach for further expanding power density and can be widely applied in the field of robotics. During characterization, this semi-active ankle exoskeleton can effectively complete the movement state of upstairs and walking, achieve an effective power of 180 N, and store maximum energy up to 5J for the human ankle.

An adaptive bionic sensor: enhancing ankle joint tracking with high sensitivity and superior cushioning performance

Flexible sensors are renowned for their rapid responsiveness, high flexibility, and outstanding mechanical properties, making them ideal for applications in wearable devices, sports and health monitoring, and human-machine interfaces. To enhance the sensing performance of these flexible sensors, researchers have drawn inspiration from nature, creating various bionic microstructures. However, these structures often manifest in the macroscopic form of thin films, which do little to improve impact resistance and joint protection. In response, this work achieves a highly sensitive and impact-resistant pressure sensor by integrating bionic principles at both micro and macro levels. Specifically, at the micro level, a muscle-like hydrogel system consisting of MXene nanosheets incorporated into the double network of polyvinyl alcohol and sodium alginate matrix is selected. At the macro level, the bionic prototypes of mimosa leaves and durian spikes with good energy absorption structure, together with octopus’ sucker with good adsorption capacity are selected, and the synergistic construction of the three structures is realized through 3D printing methods. The obtained sensor has an appropriate response range, sensitivity and stability. More importantly, the displacement deformation of the hydrogel can be reduced by 91.22%, while its adhesion strength can be increased by 57.5% compared to the unstructured hydrogel. As a proof-of-concept, the proposed bionic flexible sensor can be used to monitor the motion status of the human ankle joint in real-time, thereby assisting users in making real-time judgments on gait health.

Which tendon graft to choose for anatomical ligament reconstruction in chronic lateral ankle instability? A biomechanical study

BackgroundThe need for anatomic lateral ligament reconstruction of the ankle continues to grow. This procedure usually requires a gracilis autograft or in some cases an allograft. Siegler et al. reported the mechanical characteristics of the collateral lateral ligaments of the human ankle: 231 ± 129 N for the ATFL and 307 ± 142 N for the CFL.The objective of this study was to evaluate the mechanical properties of different tendon grafts available for ATFL and CFL reconstruction. We hypothesized that the properties of the tested grafts are not inferior to the published values of those of the original ligaments on the lateral side of the ankle. MethodsThis was a comparative biomechanical study using 6 cadaver specimens (108 grafts): The biomechanical properties of nine types of grafts were determined using validated tensile testing methods: Gracilis, SemiT, EHL, FHL, Plantaris, Peroneus longus and brevis, TA and TP.The main outcome measure was the comparison of the mechanical properties of each single-stranded tendon with each other and with the known values ​​for the ATFL and CFL, during a uniaxial static rupture test. ResultsThe mean load to failure for the gracilis was 257.5 ± 52.9 N. The groups had similar mean values in terms of the maximum load that they could withstand before failing except for the plantaris (137.9 ± 33.7 N) which was statistically lower than all other tested tendons (p < 0,01).The mean load to failure values of the grafts tested were equal or higher than that of the ATFL and CFL reported by Siegler et al. [14]: 231 ± 129 N for the ATFL and 307 ± 142 N for the CFL, while the grafts tested here had mean failure load between 258 ± 53 N and 464 ± 136 N. ConclusionThe gracilis, peroneus longus/brevis, EHL, FHL, TA, TP and semiT are legitimate grafts for combined ATFL and CFL reconstruction in the ankle. These tendons have mechanical properties (load to failure, maximum strain at failure and stiffness) that are equal to or higher than the native ligaments on the lateral side of the ankle, except the plantaris. Clinical relevanceThis study validates the current use of the gracilis autograft for the anatomical reconstruction of the ATFL and CFL, and even provides proof that other tendons would be suitable for this anatomical reconstruction of the lateral ankle ligament by auto or even allograft under certain conditions. Level of evidenceDescriptive laboratory study.

A lightweight passive ankle exoskeleton adjusted stiffness by shape memory alloy

PurposeThe purpose of this paper is to actively calibrate power density to match the application requirements with as small an actuator as possible. So, this paper introduces shape memory alloy to design variable stiffness elements. Meanwhile, the purpose of this paper is also to solve the problem of not being able to install sensors on shape memory alloy due to volume limitations.Design/methodology/approachThis paper introduces the design, modeling and control process for a variable stiffness passive ankle exoskeleton, adjusting joint stiffness using shape memory alloy (SMA). This innovative exoskeleton aids the human ankle by adapting the precompression of elastic components by SMA, thereby adjusting the ankle exoskeleton’s integral stiffness. At the same time, this paper constructs a mathematical model of SMA to achieve a dynamic stiffness adjustment function.FindingsUsing SMA as the driving force for stiffness modification in passive exoskeletons introduces several distinct advantages, inclusive of high energy density, programmability, rapid response time and simplified structural design. In the course of experimental validation, this ankle exoskeleton, endowed with variable stiffness, proficiently executed actions like squatting and walking and it can effectively increase the joint stiffness by 0.2 Nm/Deg.Originality/valueThe contribution of this paper is to introduce SMA to adjust the stiffness to actively calibrate power density to match the application requirements. At the same time, this paper constructs a mathematical model of SMA to achieve a dynamic stiffness adjustment function.

Advanced sampling discovers apparently similar ankle models with distinct internal load states under minimal parameter modification

Creating valid and trustworthy models is a key issue in biomedical engineering that affects the quality of life of both patients and healthy individuals in various scientific and industrial domains. This however is a difficult task due to the complex nature of biomechanical joints. In this study, a sampling strategy combining Genetic Algorithm and clustering is proposed to investigate biomechanical joints. A computational model of a human ankle joint with 43 input parameters serves as an illustrative case for the procedure. The Genetic Algorithm is used to efficiently search for distinct variants of the model with similar output, while clustering helps to quantify the obtained results. The search is performed in a close vicinity to the original model, mimicking subjective decisions in parameter acquisition. The method reveals twelve distinct clusters in the model parameter set, all resulting in the same angular displacements. These clusters correspond to three unique internal load states for the model, confirming the complex nature of the ankle. The proposed approach is general and could be applied to study other models in mechanical engineering and robotics.

The precision of technical aspects in the minimally invasive Broström–Gould procedure: a cadaveric anatomical study

BackgroundA comprehensive understanding of the anatomy of the anterolateral ankle joint and its interrelationships is essential for advancing the development of minimally invasive Broström–Gould procedure, thereby enhancing surgical efficacy and minimizing postoperative complications.MethodsTen fresh human ankle specimens were dissected to observe the shape and trajectory of the lateral bundle of the inferior extensor retinaculum (IER) and its relationship with the deep fascia. To observe the relationship between the ankle capsule and the anterior talofibular ligament (ATFL). The center of the insertion point of ATFL at the lateral malleolus was used as the reference point. The vertical distance from the reference point to the fibula tip, the horizontal distance from the reference point to the lateral branch of the superficial peroneal nerve, the shortest distance from the reference point to IER, the narrowest width of the IER, the angle between the line connecting the shortest distance from the reference point to the IER and the longitudinal axis of the fibula were measured. The tension and elasticity of ATFL was understood. To describe the minimally invasive Broström–Gould procedure according to the anatomical characteristics of the anterolateral ankle joint.ResultsAmong the 10 cases, 8 cases (80%) had double bundles of ATFL, 2 cases (20%) had single bundle of ATFL, and no outer superior oblique bundle was observed in IER. The vertical distance from the reference point to the fibula tip was 1.2 ± 0.3 (range 1.1–1.3) mm. The shortest distance from the reference point to the level of the superficial peroneal branch was 28.2 ± 4.3 (range 24.5–32.4) mm. The shortest distance from the reference point to IER was 12.5 ± 0.6 (range 12.1–12.9) mm, and the width of IER at this point was 7.2 ± 0.3 (range 7.0–7.6) mm. The angle between the line connecting the shortest distance from the reference point to the IER and the longitudinal axis of the fibula was about 60° ± 2.8° (range 58.1°–62.1°) mm. The space between the anterolateral deep fascia of the ankle joint and the ankle capsule is very small, and only a few fat granules are separated between them. The ATFL is largely fused to the ankle capsule. The ATFL exhibited high tension and poor elasticity after traction with the probe hook.ConclusionsThe results showed that in the minimally invasive Broström–Gould technique for lateral ankle stabilization, the Broström procedure actually sutured the insertion of the ATFL together with the ankle capsule to the anterior edge of the lateral malleolus. In the Gould procedure, the deep fascia was mostly reinforced with the ankle capsule. The minimum suture span was obtained when the Gould suture needle direction was at an Angle of 60° to the longitudinal axis of the fibula.

Intelligent ankle–foot prosthesis based on human structure and motion bionics

The ankle–foot prosthesis aims to compensate for the missing motor functions by fitting the motion characteristics of the human ankle, which contributes to enabling the lower-limb amputees to take care of themselves and improve mobility in daily life. To address the problems of poor bionic motion of the ankle–foot prosthesis and the lack of natural interaction among the patient, prosthesis, and the environment, we developed a complex reverse-rolling conjugate joint based on the human ankle–foot structure and motion characteristics, the rolling joint was used to simulate the rolling-sliding characteristics of the knee joint. Meanwhile, we established a segmental dynamics model of the prosthesis in the stance phase, and the prosthetic structure parameters were obtained with the optimal prosthetic structure dimensions and driving force. In addition, a carbon fiber energy-storage foot was designed based on the human foot profile, and the dynamic response of its elastic strain energy at different thicknesses was simulated and analyzed. Finally, we integrated a bionic ankle–foot prosthesis and experiments were conducted to verify the bionic nature of the prosthetic joint motion and the energy-storage characteristics of the carbon fiber prosthetic foot. The proposed ankle–foot prosthesis provides ambulation support to assist amputees in returning to social life normally and has the potential to help improve clinical viability to reduce medical rehabilitation costs.

Design and performance analysis of the 4UPS-RRR parallel ankle rehabilitation mechanism

Abstract. Ankle sprains are among the most common musculoskeletal injuries. Patients often require systematic rehabilitation training to expedite tissue healing and facilitate joint recovery. However, such training places high demands on medical staff, involves a lengthy process, requires considerable labor, and suffers from a shortage of skilled rehabilitation personnel. To address the need for effective ankle joint dysfunction rehabilitation training, this study analyzes the bone structure and movement mechanism of the ankle. Drawing on the parallel mechanism configuration, we propose a 4UPS-RRR parallel ankle rehabilitation mechanism. The rotation center of the rehabilitation mechanism can be highly coincident with the rotation center of the human ankle joint. The structure and degrees of freedom of the mechanism were designed and analyzed using screw theory. Additionally, a kinematic model of the mechanism was established. The mechanism's workspace was mapped by constraining the linear actuator length and spherical joint rotation angle. Furthermore, the mechanism's dexterity was assessed through the establishment of its Jacobian matrix, with the correctness of the kinematic model verified through simulation. Finally, an experimental platform was utilized to test the maximum range of robot motion, confirming the practicality of the ankle rehabilitation mechanism.

Development and Validation of Robotic Ankle Exoskeleton With Parallel Nonlinear Elastic Actuator

Abstract This paper presents the development of a robotic ankle exoskeleton for human walking assistance. First, the biomechanical properties of a human ankle joint during walking are presented. Next, design of the robotic ankle exoskeleton is introduced. The exoskeleton is actuated by a novel parallel nonlinear elastic actuator. The cam-spring mechanism in the actuator can function as a parallel nonlinear spring with an adjustable stiffness, and the design of the cam profile curve is described. Additionally, an adaptive controller is proposed for the exoskeleton to generate a desired assistive torque according to the wearer's total weight. Finally, experiments are conducted to validate the effectiveness of the developed robotic ankle exoskeleton. The experimental results demonstrate that during a gait cycle, reductions of 42.7% and 40.1% of the peak and average currents of the driving motor in the actuator are observed, respectively, with the designed cam-spring mechanism. A peak assistive torque of 23.9 Nm can be provided for the wearers by the exoskeleton during walking. With the assistance provided by the exoskeleton, the average and peak soleus activities of the wearers during a gait cycle are decreased by 25.42% and 31.94%, respectively.

A methodology to restrict the range of motion of joints: Application to the ankle joint complex

One of the most critical aspects when developing biomechanical models is the formulation of the joints, which, in the case of the human body, have limited range of motion (RoM). Thus, restrictions to prevent joints from performing unacceptable movements and avoid unrealistic configurations of the adjacent bodies must be formulated. This study extends the authors’ previous work to demonstrate the potential of applying a methodology to restrict the RoM of joints to the complex case of the human ankle joint complex. The methodology applies joint resistance moments to the adjacent bodies to mimic the resistive and dissipative behavior of the constituent materials and to prevent unacceptable configurations of those bodies. A detailed description of the application of the methodology to the ankle joint complex is given, including the definition of the joint's local reference frames and circumduction cones, estimation of the longitude and latitude, calculation of the maximum latitude using the elliptical approach and the transfer of forces and moments to the adjacent bodies. The methodology correctly restricts the RoM of the ankle joint complex, producing physiologically sound simulation results.

Intrinsic motoneuron properties in typical human development.

Motoneuron properties and their firing patterns undergo significant changes throughout development and in response to neuromodulators such as serotonin. Here, we examined the age-related development of self-sustained firing and general excitability of tibialis anterior motoneurons in a young development (7-17years), young adult (18-28years) and adult (32-53years) group, as well as in a separate group of participants taking selective serotonin reuptake inhibitors (SSRIs, aged 11-28years). Self-sustained firing, as measured by ΔF, was larger in the young development (∼5.8Hz, n=20) compared to the young adult (∼4.9Hz, n=13) and adult (∼4.8Hz, n=8) groups, consistent with a developmental decrease in self-sustained firing mediated by persistent inward currents (PIC). ΔF was also larger in participants taking SSRIs (∼6.5Hz, n=9) compared to their age-matched controls (∼5.3Hz, n=26), consistent with increased levels of spinal serotonin facilitating the motoneuron PIC. Participants in the young development and SSRI groups also had higher firing rates and a steeper acceleration in initial firing rates (secondary ranges), consistent with the PIC producing a steeper acceleration in membrane depolarization at the onset of motoneuron firing. In summary, both the young development and SSRI groups exhibited increased intrinsic motoneuron excitability compared to the adults, which, in the young development group, was also associated with a larger unsteadiness in the dorsiflexion torque profiles. We propose several intrinsic and extrinsic factors that affect both motoneuron PICs and cell discharge which vary during development, with a time course similar to the changes in motoneuron firing behaviour observed in the present study. KEY POINTS: Neurons in the spinal cord that activate muscles in the limbs (motoneurons) undergo increases in excitability shortly after birth to help animals stand and walk. We examined whether the excitability of human ankle flexor motoneurons also continues to change from child to adulthood by recording the activity of the muscle fibres they innervate. Motoneurons in children and adolescents aged 7-17years (young development group) had higher signatures of excitability that included faster firing rates and more self-sustained activity compared to adults aged ≥18years. Participants aged 11-28years of age taking serotonin reuptake inhibitors had the highest measures of motoneuron excitability compared to their age-matched controls. The young development group also had more unstable contractions, which might partly be related to the high excitability of the motoneurons.

Configuration and Kinematics of a 3-DOF Generalized Spherical Parallel Mechanism for Ankle Rehabilitation

The kinematic equivalent model of an existing ankle-rehabilitation robot is inconsistent with the anatomical structure of the human ankle, which influences the rehabilitation effect. Therefore, this study equates the human ankle to the UR model and proposes a novel three degrees of freedom (3-DOF) generalized spherical parallel mechanism for ankle rehabilitation. The parallel mechanism has two spherical centers corresponding to the rotation centers of tibiotalar and subtalar joints. Using screw theory, the mobility of the parallel mechanism, which meets the requirements of the human ankle, is analyzed. The inverse kinematics are presented, and singularities are identified based on the Jacobian matrix. The workspaces of the parallel mechanism are obtained through the search method and compared with the motion range of the human ankle, which shows that the parallel mechanism can meet the motion demand of ankle rehabilitation. Additionally, based on the motion-force transmissibility, the performance atlases are plotted in the parameter optimal design space, and the optimum parameter is obtained according to the demands of practical applications. The results show that the parallel mechanism can meet the motion requirements of ankle rehabilitation and has excellent kinematic performance in its rehabilitation range, which provides a theoretical basis for the prototype design and experimental verification.

Design of Human–Machine Compatible Ankle Rehabilitation Robot Based on Equivalent Human Ankle Model

Design of Human–Machine Compatible Ankle Rehabilitation Robot Based on Equivalent Human Ankle Model

Modeling and Control of Two Degree of Freedom Bionic Foot

Many people are affected by conditions like stroke, spinal cord diseases, cerebral palsy, and nerve injuries, leading to impaired leg function. Bionic foot assist in maintaining stability and posture, offering vital aid to those with mobility issues for improved quality of life and rehabilitation. Consequently, the use of bionic foot has increased. Bionic foot comprising electrical and mechanical components, provide comfort and support for individuals with mobility problems. An encouraging solution is to introduce bionic foot robots to help patients having mobility problems during their recovery journey. Designed to mimic the human skeletal system, these robots offer valuable assistance in restoring the natural gait cycle of patients having mobility problems. The proposed approach introduces a bionic foot designed to support movement of human ankle joint, marking a significant advancement in rehabilitation technology. Although human ankle joint actually exhibits 3 DOF motion, we consider 2 DOF motion of human ankle joint i.e., plantarflexion and dorsiflexion and, inversion and eversion as they are dominant during normal motion of human body. We designed two systems to control the motion of human ankle joint. Firstly, we have used two actuators, one for each degree of freedom to control the motion of ankle joint. Secondly, we have used an actuator to control the plantarflexion and dorsiflexion motion and Spring-Damper system to control the inversion and eversion motion of the human ankle joint. For both systems, we derive the mathematical model and then we design the PD controller using MATLAB/Simulink. For plantarflexion and dorsiflexion motion, we give standard pattern of human ankle gait as input and for inversion and eversion motion, we provide pulsating signal as our input for both the systems. After implementation, the response of the human ankle motion was precise, accurate and smooth. The torque applied by the actuators was also in the acceptable range.

Configuration Design and Kinematic Performance Analysis of a Novel 4-DOF Parallel Ankle Rehabilitation Mechanism with Two Virtual Motion Centers

Aiming at the problem that the existing ankle rehabilitation robot is difficult to fully fit the complex motion of human ankle joint and has poor human-machine motion compatibility, an equivalent series mechanism model that is highly matched with the actual bone structure of the human ankle joint is proposed and mapped into a parallel rehabilitation mechanism. The parallel rehabilitation mechanism has two virtual motion centers (VMCs), which can simulate the complex motion of the ankle joint, adapt to the individual differences of various patients, and can meet the rehabilitation needs of both left and right feet of patients. Firstly, based on the motion properties and physiological structure of the human ankle joint, the mapping relationship between the rehabilitation mechanism and ankle joint is determined, and the series equivalent model of the ankle joint is established. According to the kinematic and constraint properties of the ankle equivalent model, the configuration design of the parallel ankle rehabilitation robot is carried out. Secondly, according to the intersecting motion planes theory, the full-cycle mobility of the mechanism is proved, and the continuous axis of the mechanism is judged based on the constraint power and its derivative. Then, the kinematics of the parallel ankle rehabilitation robot is analyzed. Finally, based on the OpenSim biomechanical software, a human-machine coupling rehabilitation simulation model is established to evaluate the rehabilitation effect, which lays the foundation for the formulation of a rehabilitation strategy for the later prototype.

Human-in-the-Loop Adaptive Control of a Soft Exo-Suit With Actuator Dynamics and Ankle Impedance Adaptation.

Soft exo-suit could facilitate walking assistance activities (such as level walking, upslope, and downslope) for unimpaired individuals. In this article, a novel human-in-the-loop adaptive control scheme is presented for a soft exo-suit, which provides ankle plantarflexion assistance with unknown human-exosuit dynamic model parameters. First, the human-exosuit coupled dynamic model is formulated to express the mathematical relationship between the exo-suit actuation system and the human ankle joint. Then, a gait detection approach, including plantarflexion assistance timing and planning, is proposed. Inspired by the control strategy that is used by the human central nervous system (CNS) to handle interaction tasks, a human-in-the-loop adaptive controller is proposed to adapt the unknown exo-suit actuator dynamics and human ankle impedance. The proposed controller can emulate human CNS behaviors which adapt feedforward force and environment impedance in interaction tasks. The resulting adaptation of actuator dynamics and ankle impedance is demonstrated with five unimpaired subjects and implemented on a developed soft exo-suit. The human-like adaptivity is performed by the exo-suit in several human walking speeds and illustrates the promising potential of the novel controller.

An ultrastructural report of human articular cartilage resident cells in correlation with their phenotypic characteristics

ABSTRACT The recent discovery of progenitors based on their differential fibronectin-adhesion (FAA-CPs) and migratory-based (MCPs) assay has evoked interest due to their superiority in terms of their efficient chondrogenesis and reduced hypertrophic propensity. This study aims to isolate and enrich three articular cartilage subsets, chondrocytes, FAA-CPs, and MCPs, and compare their undifferentiated and chondrogenic differentiated status, using in-vitro phenotypical characterization in correlation with ultrastructural analysis using Transmission Electron Microscopy (TEM). Following informed consent, cartilage shavings were procured from a non-diseased human ankle joint and cultured to obtain the three subsets. Chondrocytes exhibited higher CD106 and lower CD49b and CD146 levels. Following chondrogenic differentiation, corroborative results were seen, with the MCP group showing the highest GAG/DNA ratio levels and uptake of extracellular matrix stain as compared to the FAA-CP group. TEM analysis of the chondrocytes revealed the presence of more autolytic cells with disintegrated cytoplasm and plasma membrane. The differentiated FAA-CPs and MCPs displayed higher collagen and rough endoplasmic reticulum. The results presented in this study provide novel information on the ultrastructural characteristics of cartilage resident cells, with the chondrocyte group displaying features of terminal differentiation. Both progenitor subtypes showed superiority in varied contexts, with greater collagen fibrils and greater GAG content in MCPs. The display of preferential and differentiation traits sheds insight on the necessity to enrich progenitors and coculturing them with the general pool of constituent cells to combine their advantages and reduce their drawbacks to achieve a regenerative tissue displaying genuine hyaline-like repair while limiting their terminal differentiation.

Applying Screw Theory to Design the Turmell-Bot: A Cable-Driven, Reconfigurable Ankle Rehabilitation Parallel Robot

The ankle is a complex joint with a high injury incidence. Rehabilitation Robotics applied to the ankle is a very active research field. We present the kinematics and statics of a cable-driven reconfigurable ankle rehabilitation robot. First, we studied how the tendons pull mid-foot bones around the talocrural and subtalar axes. We proposed a hybrid serial-parallel mechanism analogous to the ankle. Then, using screw theory, we synthesized a cable-driven robot with the human ankle in the closed-loop kinematics. We incorporated a draw-wire sensor to measure the axes’ pose and compute the product of exponentials. We also reconfigured the cables to balance the tension and pressure forces using the axis projection on the base and platform planes. Furthermore, we computed the workspace to show that the reconfigurable design fits several sizes. The data used are from anthropometry and statistics. Finally, we validated the robot’s statics with MuJoCo for various cable length groups corresponding to the axes’ range of motion. We suggested a platform adjusting system and an alignment method. The design is lightweight, and the cable-driven robot has advantages over rigid parallel robots, such as Stewart platforms. We will use compliant actuators for enhancing human–robot interaction.

Identification and Analysis of the Ankle Microbiome Using Next-Generation DNA Sequencing: An Observational Analysis.

Next-generation DNA sequencing (NGS) technologies have increased the sensitivity for detecting the bacterial presence and have been used in other areas of orthopaedics to better understand the native microbiome of various joints. This study uses NGS to determine whether (1) a unique microbiome exists in human ankle tissues, (2) if components of the ankle microbiome affect patient outcomes, and (3) whether microbes found on the skin are a normal part of the ankle microbiome. A prospective study recruited 32 patients undergoing total ankle arthroplasty (n = 23) or ankle arthrodesis (n = 9) via direct anterior approach between November 2020 and October 2021. During surgery, five layers of the ankle were swabbed: skin (n = 32), retinaculum (n = 31), tibialis anterior tendon (n = 31), joint capsule (n = 31), and distal tibia (n = 32). These swabs (N = 157) were sent to MicroGen Diagnostics (Lubbock) for NGS. Demographics, medical comorbidities, surgical indication, postoperative complications, readmission, and revision surgery rates were collected from patient records. The mean age was 60.7 (range, 19 to 85) years, and the mean follow-up duration was 10.2 (range, 4.8 to 20.6) months. Of 157 swabs sent for NGS, 19 (12.1%) indicated that bacteria were present (positive), whereas the remaining 138 (87.9%) had no bacteria present (negative). The most common organisms were Cutibacterium acnes in eight ankles (25.0%) and Staphylococcus epidermidis in two ankles (6.25%). Most bacteria were found in the retinaculum (29.6%). Complications, nonunions, infections, 90-day readmission, and revision surgery rates did not differ by NGS profile. This study found that C acnes and S epidermidis were the most common bacteria in the ankle microbiome, with C acnes being present in 25% of ankles. Complication rates did not differ between patients with or without positive bacterial DNA remnants. Thus, we concluded that a unique ankle microbiome is present in some patients, which is unique from that of the skin of the ankle. Level II, Prospective cohort study.