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The shape of the talus, its internal structure, and its mechanical properties are important in determining talar behavior during loading, which may be significant for the design of surgical tools and implants. Although recent studies using statistical shape modeling have described quantitative talar external shape variation, no similar quantitative study exists to describe the density distribution of internal talar structure. The goal of this study is to quantify statistical variation in talar shape and density to benefit the design of talar implants. To this end, weight-bearing computed tomography (CT) scans of the ankle were collected in neutral, bilateral standing posture, and three-dimensional models were generated for each talus. Local density derived from the Hounsfield unit of each CT voxel was extracted. A weighted spherical harmonic analysis was performed to quantify the talar external shape. One hundred and seventy-nine volumes of interest were placed in the same relative position within each talus to quantify the talar density. Additionally, a finite element analysis (FEA) was conducted on a talus with both heterogeneous and homogeneous material properties to observe the effect of these properties on the stress and strain response. Significant differences were found in the talar density in sex and age, as well as in the stress and strain response between homogeneous and heterogeneous FEA. These differences show the importance of considering heterogeneity when examining the load response of tarsal bones., (© 2024 Orthopaedic Research Society.)

Background: Cadaver biomechanical testing suggests that the morphology of articulating bones contributes to the stability of the joints and determines their kinematics; however, there are no studies examining the correlation between bone morphology and kinematics of the subtalar joint. The purpose of this study was to investigate the influence of talar and calcaneal morphology on subtalar kinematics during walking in healthy individuals., Methods: Forty ankles (20 healthy subjects, 10 women/10 men) were included. Participants walked at a self-selected pace while synchronized biplane radiographs of the hindfoot were acquired at 100 images per second during stance. Motion of the talus and calcaneus was tracked using a validated volumetric model-based tracking process, and subtalar kinematics were calculated. Talar and calcaneal morphology were evaluated using statistical shape modeling. Pearson correlation coefficients were used to assess the relationship between subtalar kinematics and the morphology features of the talus and calcaneus., Results: This study found that a shallower posterior facet of the talus was correlated with the subtalar joint being in more dorsiflexion, more inversion, and more internal rotation, and higher curvature in the posterior facet was correlated with more inversion and eversion range of motion during stance. In the calcaneus, a gentler slope of the middle facet was correlated with greater subtalar inversion., Conclusion: The morphology of the posterior facet of the talus was found to a primary factor driving multiplanar subtalar joint kinematics during the stance phase of gait., Clinical Relevance: This new knowledge relating form and function in the hindfoot may assist in identifying individuals susceptible to subtalar instability and in improving implant design to achieve desired kinematics after surgery., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Disclosure forms for all authors are available online.

Background: Landing from heights is a common movement for active-duty military personnel during training. And the additional load they carry while performing these tasks can affect the kinetics and ankle kinematic of the landing. Traditional motion capture techniques are limited in accurately capturing the in vivo kinematics of the talus. This study aims to investigate the effect of additional trunk load on the kinematics of the talocrural and subtalar joints during landing, using a dual fluoroscopic imaging system (DFIS)., Methods: Fourteen healthy male participants were recruited. Magnetic resonance imaging was performed on the right ankle of each participant to create three-dimensional (3D) models of the talus, tibia, and calcaneus. High-speed DFIS was used to capture the images of participants performing single-leg landing jumps from a height of 40 cm. A weighted vest was used to apply additional load, with a weight of 16 kg. Fluoroscopic images were acquired with or without additional loading condition. Kinematic data were obtained by importing the DFIS data and the 3D models in virtual environment software for 2D-3D registration. The kinematics and kinetics were compared between with or without additional loading conditions., Results: During added trunk loading condition, the medial-lateral translation range of motion (ROM) at the talocrural joint significantly increased (p < 0.05). The subtalar joint showed more extension at 44-56 ms (p < 0.05) after contact. The subtalar joint was more eversion at 40-48 ms (p < 0.05) after contact under the added trunk load condition. The peak vertical ground reaction force (vGRF) significantly increased (p < 0.05)., Conclusions: With the added trunk load, there is a significant increase in peak vGRF during landing. The medial-lateral translation ROM of the talocrural joint increases. And the kinematics of the subtalar joint are affected. The observed biomechanical changes may be associated with the high incidence of stress fractures in training with added load., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This paper aimed to investigate the biomechanical changes during the talus impact with the calcaneus at varying velocities. Various three-dimensional reconstruction software was utilized to construct a finite element model that consisted of the talus, calcaneus, and ligaments. The explicit dynamics method was used to explore the process of the talus impacting on the calcaneus. The velocity of impact was altered from 5 m/s to 10 m/s with a 1 m/s interval. Stress readings were collected from the posterior, intermediate, and anterior subtalar articular (PSA, ISA, ASA), calcaneocubic articular (CA), Gissane Angle (GA), calcaneal base (BC), medial wall (MW), and lateral wall (LW) of the calcaneus. The changes in the amount and distribution of stress in the different regions of the calcaneus that varied with velocity were analysed. The model was validated through comparison with findings from the existing literature. During the process of impact between the talus and calcaneus, the stress in the PSA reached its peak first. Notably, stress was concentrated mainly in the PSA, ASA, MW, and LW of the calcaneus. At varying impact velocities of the talus, the mean maximum stress of the PSA, LW, CA, BA, and MW exhibited statistically significant differences (P values were 0.024, 0.004, <0.001, <0.001, and 0.001, respectively). However, the mean maximum stress of the ISA, ASA, and GA was not statistically significant (P values were 0.289, 0.213, and 0.087, respectively). In comparison with the velocity at 5 m/s, the mean maximum stress increases in each region of the calcaneus at a velocity of 10 m/s were as follows: PSA 73.81%, ISA 7.11%, ASA 63.57%, GA 89.10%, LW 140.16%, CA 140.58%, BC 137.67%, MW 135.99%. The regions of stress concentration were altered, and the magnitude and sequence of peak stress in the calcaneus also varied according to the velocity of the talus during impact. In conclusion, the velocity of the talus during impact had a significant influence on the magnitude and distribution of stress within the calcaneus, which was a crucial factor in the development of calcaneal fractures. It was possible that the magnitude and sequence of stress peaks played a vital role in determining the emergence of fracture patterns.

Background: There are different surgical methods for primary malignant tumor located at distal tibia. Previous studies have reported that double-strut fibula ankle arthrodesis is an alternative option. The purpose of this study was to investigate the biomechanical effect of double-strut fibula ankle arthrodesis by finite element analysis (FEA)., Methods: Computer-aided design software was used to establish three-dimension models. Three different models were constructed: normal tibia-fibula-talus complex (model A), double-strut fibula ankle arthrodesis (model B), and reconstruction by ipsilateral fibula (model C). We used FEA to evaluate and compare the biomechanical characteristics of these constructs. Simulated load of 600 N was applied to the tibial plateau to simulate balanced single-foot standing. Output results representing the model von Mises stress and displacement of the components were analyzed., Results: Construct stiffness was increased when the internal plate fixation was used. For axial load, model B (1460.5 N/mm) was stiffer than the construct of model A (524.8 N/mm), and model C (636.6 N/mm), indicating model B was more stable. Maximum stress on the fibular graft occurred on the proximal end. The von Mises stress and stress distribution of fibular graft in model B (71.4 MPa) and model C (67.8 MPa) were similar. In model B, the ipsilateral fibula in model B has a higher value of stress (16.1 MPa) than that in model A (0.5 MPa), indicating the ipsilateral fibula shared load after fusion with talus., Conclusions: Our computational findings suggest that double-strut fibula ankle arthrodesis is an acceptable construct for distal tibia defect and the ipsilateral fibula shares load after fusion with talus.

Background: Osteochondral lesions of the talus (OCLTs) secondary to ankle fractures have previously been reported in the literature. However, no study has evaluated OCLTs using magnetic resonance imaging (MRI) following ankle fracture treatment. The purpose of our study was to investigate accompanying OCLTs in patients with an ankle fracture and evaluate its relationship with the clinical outcomes., Methods: Fifty-six patients with ankle fractures who were treated with either a nonoperative or operative method at our center between June 2016 and February 2017 were included in this prospective comparative study (37 men and 19 women; mean age, 44.6 ± 13 years; range, 20-65 years). The mean American Orthopaedic Foot & Ankle Society (AOFAS) scores were used to evaluate the clinical results in all patients in the second month and second year. The second-month ankle MR images were evaluated for OCLTs in all patients. Thirty patients were treated operatively and 26 nonoperatively., Results: Accompanying OCLTs were detected in 19 of 56 patients (34%). Our results showed no statistically significant association between OCLT and fracture type, as well as the treatment type. In the second postoperative month, the mean AOFAS scores were 87.2 ± 10.8 and 77.6 ± 12.0 in patients with and without OCLTs, respectively ( P = .005). In the second postoperative year, the mean AOFAS scores were 81.3 ± 6.8 and 86.2 ± 8.4 in patients with and without OCLTs, respectively ( P = .031). The mean AOFAS score significantly decreased in the OCLT group in the second-year control, whereas a significant increase was observed in patients without OCLTs ( P = .026 and P < .001, respectively)., Conclusion: According to our results, the accompanying OCLTs were found in one-third of patients treated for ankle fractures. We observed a significant correlation between OCLT presence and the AOFAS score. According to the AOFAS score, OCLTs statistically significantly affected clinical results at 2 years., Level of Evidence: Level II, prospective comparative study.

The purpose of the present study was to identify the effects of anterior translation and medial rotation of the talus on ankle joint contact forces (AJF) during double-limb vertical hopping. A computational musculoskeletal model was used to calculate AJF under 225 different combinations of 0-10 mm (in 10/15 mm increments) anterior translation and 0-5° (in 5/15° increments) medial rotation for ten subjects. The results show anteroposterior AJF was moderately affected by anterior translation, while mediolateral AJF was strongly affected by medial rotation. Future research should investigate if interventions that manipulate misaligned talus position in-vivo can also reduce AJF.

Background: Ankle range of motion declines with age, affecting mobility and postural control., Objective: The objective of this study was to investigate the effects of a talus mobilization-based intervention among healthy community-dwelling older adults presenting with limited weight-bearing ankle dorsiflexion range of motion and determine how ankle mobility evolved over the treatment., Design: This was a randomized clinical trial., Setting: This study was conducted in an outpatient clinic., Participants: Community-dwelling, older adults over 60 years of age who had limited ankle mobility participated in this study., Interventions: The experimental intervention consisted of 6 sessions of manual therapy applied in the ankle joint. The control group received the same volume of sham treatment., Measurements: The primary outcome was the weight-bearing ankle dorsiflexion range of motion as measured using the lunge test. Data were collected at 9 time points: baseline, after each session, and follow-up., Results: A total of 36 participants were analyzed. A single session of mobilization increased ankle range of motion by 8 degrees (95% confidence interval = 6 to 11). At the end of the sixth session, this effect had increased slightly to 11 degrees (95% confidence interval = 9 to 13). Significant between-group differences were found throughout the intervention., Limitations: Optimal dose and effects from follow-up evaluations for treatment volumes of fewer than 6 sessions remain unknown., Conclusions: Six sessions of a talus mobilization-based intervention in healthy community-dwelling older adults found that the greatest mobility gain in terms of the weight-bearing ankle dorsiflexion range of motion is produced after the first session. Additional sessions produce smaller improvements with a slight upward trend. Importantly, the restoration of joint mobility is enhanced over time after the end of the intervention., (© 2020 American Physical Therapy Association.)

Objective: To determine the rate of return of patients to sport after arthroscopic autologous matrix-induced chondrogenesis (AT-AMIC) for outcomes 2 years after surgery., Design: Retrospective observational cross-sectional study., Setting: C.A.S.C.O.-Foot and Ankle Unit, Istituto Ortopedico Galeazzi, Milan, Italy., Patients and Intervention: Twenty-six consecutive patients, 65.4% male (mean ± SD age: 33.7 ± 11.0 years), that underwent AT-AMIC procedure between 2012 and 2015 were selected retrospectively. From this population, only sporting patients at amateur's level were included. Arthroscopic autologous matrix-induced chondrogenesis was proposed in patients with pain and persistent disability., Main Outcome Measures: All patients were assessed with the American Orthopaedic Foot and Ankle Score (AOFAS), physical component score of the 12-Item Short Form Health Survey (SF-12), Halasi ankle activity score, and University of California, Los Angeles (UCLA) activity scale preoperatively and at 24 months postoperatively., Results: Overall, 80.8% of the patient group returned to the same preinjury sport. The mean follow-up was 42.6 ± 10.9 months (range from 25 to 62 months). Significant differences were observed with reference to AOFAS, SF-12, Halasi, and UCLA scores at the last follow-up in patients who had undergone AT-AMIC (all, P < 0.001)., Conclusions: A high percentage of patients return to their preinjury sport after AT-AMIC surgery.

Objective:  Subchondral bone density distribution can be used to study joint biomechanics non-invasively. Differences in joint loading between related species can aid in the understanding of joint loading and the development of certain types of orthopaedic pathology. This study was conducted to evaluate density distribution in the subchondral bone of the talus of different Canidae species, as a parameter reflecting the long-term joint loading in the tarsocrural joint., Materials and Methods:  The tarsal joints of cadaveric dogs of different breeds were included, that is, German Shepherd ( n  = 5), Bouvier des Flandres ( n  = 3) and Labrador Retriever ( n  = 6).Additionally, golden jackals ( n  = 5) ( Canis aureus ) and wolves ( n  = 5) ( Canis lupus ) were included. Consecutive computed tomography slices were made and the subchondral bone density distribution was evaluated using computer tomographic osteoabsorptiometry. Different breeds and species were visually compared., Results:  Differences were found in the subchondral bone density distribution of the talus between breeds and between species ( Canis familiaris , Canis lupus and Canis aureus )., Discussion and Conclusion:  Based on the density distribution, there are differences in loading conditions of the tarsocrural joint in different species of Canidae . The joint loading distribution is very similar between dogs of the same breed and within the same species. Although between-breed differences can be explained by conformational differences, the between-species differences remain subject to further research., Competing Interests: None of the authors of this article has a financial or personal relationship with other people or organizations that could inappropriately influence or bias the content of the article., (Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: The coupled behavior of talocrural joint motion is primarily determined by the morphological features of the talar trochlea and tibiofibular mortise. Features of the radius of curvature of the talocrural joint, however, remain unclear. The objectives of this study were to evaluate the radius of curvature at the mid, medial, and lateral regions of both the talar trochlea and the tibial plafond, and to estimate subject-specific kinematics of the talocrural joint., Methods: Computed tomography images of 44 subjects with healthy talocrural joints were assessed by creating three-dimensional bone models. The radii of curvature of the anterior and posterior regions at the mid, medial, and lateral regions of both the talar trochlea and the tibial plafond were calculated. Hypothetical dorsiflexion and plantarflexion axes of the talocrural joint were estimated from the shape of the talar trochlea. Orientations and distances of these axes were calculated., Results: At both the talar trochlea and the tibial plafond, the anteromedial and posteromedial radii exhibited the largest coefficients of variation. The anterior-to-posterior radius ratio (APRR) of the medial talar trochlea significantly correlated with the mid APRR, anterior medial-to-lateral radius ratio (MLRR), and posterior MLRR of the trochlea (r = 0.45, 0.52, - 0.60, respectively, and all P < 0.01)., Conclusions: The asymmetric shape of the medial talar trochlea seems to determine a fixed or changing axis of rotation at the talocrural joint. This subject-specific rotational axis of the talocrural joint should be considered in the management of patients with ankle injuries.

Objective: The purpose of this study was to evaluate the correlation among the navicular drop test, the arch angle, the Staheli index and the Chippaux-Smirak index. The reliability and the correlation among the footprint parameters were also estimated., Methods: A cross-sectional study (n = 86; 59.3% women; 27.8 years, standard deviation: 4.8 years) was carried out. The navicular drop test was evaluated and footprint parameters using a plantar pressure platform were recorded in the dominant foot. Pearson correlation coefficients, intraclass correlation coefficient, standard error of measurement, and minimum detectable change were calculated., Results: Both intrarater and interrater reliability were excellent for all the parameters evaluated (intraclass correlation coefficients > 0.880). Statistically significant correlations existed between the navicular drop test and footprints parameters (arch angle = 0,643; Staheli index = 0.633; Chippaux-Smirak index = 0.614). The footprint parameters had excellent correlation with each other (0.838-0.881). The navicular drop test and the footprint parameters studied were reproducible and thus had excellent reliability., Conclusion: The correlations obtained between the navicular drop test and the footprint parameters evaluated were good. The navicular drop test appears to be a reproducible, valid, and simple test for evaluating medial longitudinal arch height, having fewer disadvantages than using footprint parameters., (Copyright © 2018. Published by Elsevier Inc.)

The talus is one of the most commonly preserved post-cranial elements in the platyrrhine fossil record. Talar morphology can provide information about postural adaptations because it is the anatomical structure responsible for transmitting body mass forces from the leg to the foot. The aim of this study is to test whether the locomotor behaviour of fossil Miocene platyrrhines could be inferred from their talus morphology. The extant sample was classified into three different locomotor categories and then talar strength was compared using finite-element analysis. Geometric morphometrics were used to quantify talar shape and to assess its association with biomechanical strength. Finally, several machine-learning (ML) algorithms were trained using both the biomechanical and morphometric data from the extant taxa to infer the possible locomotor behaviour of the Miocene fossil sample. The obtained results show that the different locomotor categories are distinguishable using either biomechanical or morphometric data. The ML algorithms categorized most of the fossil sample as arboreal quadrupeds. This study has shown that a combined approach can contribute to the understanding of platyrrhine talar morphology and its relationship with locomotion. This approach is likely to be beneficial for determining the locomotor habits in other fossil taxa., (© 2018 The Authors.)

The purpose of this study was to quantify isolated coupling mechanisms of calcaneal adduction/abduction and calcaneal eversion/inversion to proximal bones in vitro. The in vitro approach is necessary because in vivo both movements appear together, making it impossible to determine the extent of their individual contribution to overall ankle joint coupling. Eight fresh frozen foot-leg specimens were tested. Data describing bone orientation and coupling mechanisms between segments were obtained using bone pin marker triads. The bone movement was described in a global coordinate system to examine the coupling between the calcaneus, talus and tibia. The strength of coupling was determined by means of the slope of a linear least squares fit to an angle-angle plot. The coupling coefficients in the present study indicate that not only calcaneal eversion/inversion (coupling coefficient: 0.68 ± 0.15) but to an even greater extent calcaneal adduction/abduction (coupling coefficient: 0.99 ± 0.10) was transferred into talus and tibial rotation, highlighting the relevance of calcaneal adduction for the overall ankle joint coupling. The results of this study present the possibility that controlling calcaneal adduction/abduction can affect talus and tibial rotation and therefore the possible genesis of overuse knee injuries., (© 2018 Anatomical Society.)

Study Design Case report. Background An os trigonum can be a source of pain for dancers due to impingement during repetitive ankle plantar flexion movements. Following excision of an os trigonum, it is important to have a gradual, progressive return-to-dance program for optimal recovery. The purpose of this case report is to describe the postoperative management and return-to-dance progression of an adolescent dancer post os trigonum excision. Case Description An adolescent preprofessional female dancer had an extensive history of left posterior heel pain, beginning at age 8, that led to surgical removal of an os trigonum at age 15. Post surgery, the patient was seen for a total of 22 visits over the course of 20 weeks. Treatment included therapeutic exercises, neuromuscular re-education, and manual therapy. Return-to-dance tests and guidelines were used to safely progress to full, unrestricted dance participation. Outcomes The dancer had a full return of ankle range of motion, strength, and balance, improved patient-reported outcome scores, and was able to fully return to dance participation. Discussion Treating a dancer following os trigonum excision should involve a screen for hypermobility, clear communication with the dance instructor, awareness of dance-specific biomechanics, and proper reintegration into dance participation. Level of Evidence Therapy, level 5. J Orthop Sports Phys Ther 2018;48(3):194-203. Epub 7 Nov 2017. doi:10.2519/jospt.2018.7508.

BACKGROUND Clinical studies indicate that in total ankle arthroplasty, postoperative implant subsidence and medial tilt become two significant concerns of the ankle replacement system, and which are associated with the contact between the bones and the talar component. Up to now, little attention has focused on the contact between the bones and the talar component. MATERIAL AND METHODS In order to address implant subsidence and medial tilt, one three-dimensional finite element model of contact between the bone and the talar components was built with the material properties of the cancellous bone interpolated from the experimental data, which represents variation of material properties through the cancellous bones. The finite element model was used to study the following: variation of the Young's modulus of the bones, stiffness of the talar component, loading direction, and loading magnitude with the implant subsidence. RESULTS The computational results reveal that a variety of Young's modulus of the cancellous bones causes the medial tilting of the talar component and that big plastic strains are associated with tilting. The implant subsidence increases from 0.169 mm to 0.269 mm when the loading changes from 272 kg to 408 kg. However, to the contrary, the implant subsidence decreases from 0.2676 mm to 0.1783 mm when Young's modulus of the bones increases 50%. However, the implant subsidence shows little change with a different Young's modulus of the talar component from 88 GPa to 132 GPa. CONCLUSIONS Our study indicates that a variety of different Young's modulus of the cancellous bones cause the medial tilting of the talar component. To solve subsidence and tilting, both the contact area and the variation of material properties should be taken into account.

We investigated talus and tibial plafond subchondral bone puncture strength based on surface location. Puncture tests of the subchondral bone were performed in 9 equal zones on the articular surface of 12 cadaver specimens aged 49.1 years (range, 36-56 years). Compressive load was applied through a microfracture awl at 2 mm/min. Puncture strength was defined as the first load drop in load-deflection curves. In the talus, zone 1 (215 ± 91 N) and zone 2, the anterior medial and anterior middle zones, had significantly greater puncture strength than zones 7, 8, and 9, the posterior medial, middle, and lateral zones (104 ± 43 N, 115 ± 43 N, and 102 ± 35 N, respectively; P < .001). In the tibial plafond, zone 3, the anterior-lateral zone, and zone 7, the posterior medial zone, had significantly greater strength than zone 8, the posterior middle zone (202 ± 72 N, 206 ± 121 N, and 112 ± 65 N, respectively; P < .001) These results suggest that the subchondral bone is significantly weaker to penetrative force in the posterior region than in the anterior region of the talar dome and of the tibial plafond. These findings may have implications for microfracture awl design and for understanding the complex anatomy and physiology of the ankle joint., Levels of Evidence: Controlled laboratory study.

The aim of this study was to determine whether persistent idiopathic toe walking leads to compensatory skeletal changes in the pediatric foot and ankle. Foot radiographs of children diagnosed with idiopathic toe walking and sex-matched and age-matched controls were retrospectively reviewed. Five blinded providers assessed the foot radiographs for skeletal changes to the ankle. The relationship between each measure and toe-walking status was examined. Providers observed radiographic evidence of skeletal changes of the talus in idiopathic toe walkers compared with controls, suggesting that persistent toe walking impacts the skeletal development of the talus., Level of Evidence: prognostic level III.

Background: There is an increasing interest in the operative treatment of deltoid ligament disruption in the setting of chronic ankle instability. Understanding the vascular anatomy of the deltoid complex is beneficial when considering operative procedures on the medial ankle and may provide insight into factors that lead to chronic deltoid insufficiency and ankle instability., Methods: Thirty-two pairs of cadaveric specimens (64 total legs) were amputated below the knee, and the tibialis anterior, tibialis posterior, and peroneal arteries were injected with India ink and Ward's blue latex. Specimens then underwent chemical debridement to identify the vascular supply to the deltoid ligament. A subset of specimens also underwent intraosseous debridement using the modified Spalteholz technique., Results: The vascular supply to the deltoid ligament was clearly visualized in 60 (93.8%) specimens. Fifty-eight specimens (96.7%) had arterial supply with an origin from the medial tarsal artery, 57 specimens (95%) had supply from the tibialis posterior artery, and 23 (38.3%) specimens had supply from the tibialis anterior artery. All specimens had at least 1 location of intraosseous vascular supply, either at the medial malleolus or medial talus., Conclusion: There were 3 separate extraosseous sources and 2 intraosseous sources of vascular supply to the deltoid ligament., Clinical Relevance: Knowledge of the vascular supply may aid in identifying factors that predispose a subset of patients with medial ankle sprains to failure of conservative treatment, as well as provide useful anatomic information when considering operative treatment for chronic ankle instability.

Tali of several hominin taxa are preserved in the fossil record and studies of the external morphology of these often show a mosaic of human-like and ape-like features. This has contributed to a growing recognition of variability characterizing locomotor kinematics of Australopithecus. In contrast, locomotor kinematics of another Plio-Pleistocene hominin, Paranthropus, are substantially less well-documented, in part, because of the paucity of postcranial fossils securely attributed to the genus. Since the talus transmits locomotor-based loads through the ankle and its internal structure is hypothesized to reflect accommodation to such loads, it is a cornerstone structure for reconstructing locomotor kinematics. Here we quantify and characterize trabecular bone morphology within tali attributed to Australopithecus africanus (StW 102, StW 363, StW 486) and Paranthropus robustus (TM 1517), making quantitative comparisons to modern humans, extant non-human apes, baboons, and a hominin talus attributed to Paranthropus boisei (KNM-ER 1464). Using high-resolution images of fossil tali (25 μm voxels), nine trabecular bone subregions of interest beneath the articular surface of the talar trochlea were segmented to quantify localized patterns in distribution and primary strut orientation. It was found that trabecular strut orientation and shape, in some cases, can discriminate amongst species characterized by different locomotor foot kinematics. Discriminant function analyses using standard trabecular bone structural properties align TM 1517 with Pan and Gorilla, while other hominin tali structurally most resemble those of baboons. In primary strut orientation, Paranthropus tali (KNM-ER 1464 and TM 1517) resemble the human condition in the anterior-medial subregion, where strut orientation appears positioned to distribute compressive loads medially and distally toward the talar head. In A. africanus tali (particularly StW 486), primary strut orientation in this region resembles that of apes. These results suggest that Paranthropus may have had a human-like medial weight shift during the last half of stance phase but Australopithecus did not., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Although retrograde intramedullary nails for tibiotalocalcaneal arthrodesis (TTCA) are an established fixation method, few studies have evaluated the stability of the available nail systems. The purpose of this study was to compare biomechanically the primary stability of 2 nail-systems, A3 (Small Bone Innovations) and HAN (Synthes), in human cadavers and analyze the exact point of instability in TTCA by means of optical measurement., Methods: In 6 pairs of lower legs (n = 12) of fresh-frozen human cadavers with osteoporotic bone structure, bone mineral density (BMD) was determined. Pairwise randomized implantation of either an HAN or A3 nail was executed. Performance and stability were measured by quasi-static tests using 3D motion tracking (NDI Optotrak-Certus) followed by cyclic loading tests during dorsi- and plantarflexion., Results: 3D optical analysis in quasi-static tests showed a significantly lower degree of movement for the HAN nail in rotational and dorsi-/plantarflexion, especially in the subtalar joint. Cyclic loading tests were consistent with quasi-static tests., Conclusion: The A3 nail offered lower stability during axial torsion in the ankle and subtalar joints and during plantar- and dorsiflexion in the subtalar joint in osteoporotic bones. This study was the first to examine the primary stability of different arthrodesis nails in TTCA and their bony parts with a 3D motion analysis., Clinical Relevance: The better stability of the locking-only HAN nail in this osteoporotic test setup could lead to more favorable results in comparison to the A3 nail in clinical use.

Carotenoids are found in abundance in fruit and vegetables, and may be involved in the positive association of these foods with bone health. This study aimed to explore the associations of dietary carotenoid intakes and plasma concentrations with bone density status and osteoporotic fracture risk in a European population. Cross-sectional analyses (n 14 803) of bone density status, using calcaneal broadband ultrasound attenuation (BUA) and longitudinal analyses (n 25 439) of fracture cases were conducted on data from the prospective European Prospective Investigation into Cancer and Nutrition-Norfolk cohort of middle-aged and older men and women. Health and lifestyle questionnaires were completed, and dietary nutrient intakes were derived from 7-d food diaries. Multiple regression demonstrated significant positive trends in BUA for women across quintiles of dietary α-carotene intake (P=0·029), β-carotene intake (P=0·003), β-cryptoxanthin intake (P=0·031), combined lutein and zeaxanthin intake (P=0·010) and lycopene intake (P=0·005). No significant trends across plasma carotenoid concentration quintiles were apparent (n 4570). The Prentice-weighted Cox regression showed no trends in fracture risk across dietary carotenoid intake quintiles (mean follow-up time 12·5 years), except for a lower risk for wrist fracture in women with higher lutein and zeaxanthin intake (P=0·022); nevertheless, inter-quintile differences in fracture risk were found for both sexes. Analysis of plasma carotenoid data (mean follow-up time 11·9 years) showed lower hip fracture risk in men across higher plasma α-carotene (P=0·026) and β-carotene (P=0·027) quintiles. This study provides novel evidence that dietary carotenoid intake is relevant to bone health in men and women, demonstrating that associations with bone density status and fracture risk exist for dietary intake of specific carotenoids and their plasma concentrations.

Current methods for measuring in vivo 3D muscle-tendon moment arms generally rely on the acquisition of magnetic resonance imaging (MRI) scans at multiple joint angles. However, for patients with musculoskeletal pathologies such as fixed contractures, moving a joint through its full range of motion is not always feasible. The purpose of this research was to develop a simple, but reliable in vivo 3D Achilles tendon moment arm (ATMA) technique from a single static MRI scan. To accomplish this, for nine healthy adults (5 males, 4 females), the geometry of a cylinder was fit to the 3D form of the talus dome, which was used to estimate the talocrural flexion/extension axis, and a fifth-order polynomial fit to the line of action of the Achilles tendon. The single static scan in vivo 3D ATMA estimates were compared to estimates obtained from the same subjects at the same ankle joint angles using a previously validated 3D dynamic MRI based in vivo ATMA measurement technique. The ATMA estimates from the single scan in vivo 3D method (52.5mm±5.6) were in excellent agreement (ICC=0.912) to the validated in vivo 3D method (51.5mm±5.1). These data show reliable in vivo 3D ATMA can be obtained from a single MRI scan for healthy adult populations. The single scan, in vivo 3D ATMA technique provides researchers with a simple, but reliable method for obtaining subject-specific ATMAs for musculoskeletal modelling purposes., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: During growth, the skeletal structures adapt to the increased loading conditions and mature to a fully-grown skeleton. Subchondral bone density reflects the effect of long-term joint loading and it is expected to change over time. The aim of this study was to describe the long-term changes in the density distribution of the subchondral bone of the talus of healthy Labrador Retrievers in a prospective study., Results: The subchondral bone density distribution was evaluated using computed tomographic osteoabsorptiometry (CTOAM). Visually, all joints showed very similar density distribution patterns. No significant differences in the topography of the density maxima were found between t 1 and t 2 . The mean density, maximum density, and maximum area ratio (MAR) were significantly increased with increasing age., Conclusions: The subchondral bone density of the talus of healthy Labrador Retrievers increases with increasing age. It is likely an adaptive response of the subchondral bone due to increased joint loading during growth.

Background: In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in maximum principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesized that synovial fluid could be a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states., Methods: As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test configurations were investigated using a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous 2 bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium-owned GHBMC model, M50 version 4.2, a model of an average-sized male (distributed by Elemance, LLC, Winston-Salem, NC). The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight, and the maximum principal stress was computed., Results: All numerical simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula, and talus reduced the maximum principal stress computed in the distal tibia at maximum load from 31.3 N/mm 2 to 11.5 N/mm 2 . Following 1 mm lateral translation of the talus and fibula, there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated into the model., Conclusions: The findings in this study demonstrate a meaningful role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid was less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the tibia and should be accounted for in future experiments., Clinical Relevance: Synovial fluid may play a protective role in ankle injuries, thus delaying the onset of arthritis. Reactive joint effusions may also function to additionally redistribute stresses with higher volumes of viscous fluid., (© The Author(s) 2016.)

Three-dimensional (3D) behavior of the talocrural joint is primarily determined by the articular surface morphology of the talar trochlea and tibiofibular mortise. However, morphological features of the anterior and posterior regions of the talar trochlea remain unclear. The objectives of this study were to evaluate anterior and posterior radii of the medial and lateral talar trochlea and to estimate subject-specific kinematics of the talocrural joint. Fifty dry tali were scanned using computed tomography to create 3D bone models. Radii of curvature of the anterior and posterior region at both the medial and lateral trochlea were calculated. Orientations of the dorsiflexion and plantarflexion axis passing through the centers of the circles fitted to the anterior region of the medial and lateral trochlea and through the centers of the circles fitted to the posterior region of the medial and lateral trochlea were evaluated, respectively. The anterior radius of the medial trochlea was significantly smaller than that of the lateral trochlea by a mean of 7.8 mm (P < 0.001). The posterior radius of the medial trochlea was larger than that of lateral trochlea in 30 samples (60%) and vice versa in 20 samples (40%). Unilateral asymmetric shape of anterior trochlea would induce external rotation of the talus during ankle dorsiflexion, whereas bilateral asymmetric shape of posterior trochlea would induce opposite axial rotations among subjects during ankle plantarflexion, which would help the physical therapists to restore talocrural joint motions to ideal state for patients with ankle injuries. Clin. Anat. 29:1066-1074, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background: Recently, as total ankle arthroplasty (TAA) has been widely performed, its outcomes and complications have been reported. Heterotopic ossification (HO) after TAA has been reported in the posterior compartment of the ankle. We report on a series of HOs that developed in the anterior compartment of the ankle at the talar neck region after TAA., Methods: TAA was performed using the Hintegra and the Mobility in 54 ankles (Hintegra, 21 ankles; Mobility, 33 ankles) from 2004 to 2012. The outcome was assessed by visual analog scale (VAS), the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, patient satisfaction, and radiographic evaluation. The HO was confirmed on the lateral ankle view. HO in the anterior compartment of the ankle was classified based on a modification of the Brooker classification., Results: After TAA, 13 HOs developed in 12 of the 54 ankles. Six HOs developed in the anterior compartment, and 7 HOs developed in the posterior compartment. The majority of the anterior compartment HO (5/6) was observed in the Mobility group. There was no significant relationship between HO and the clinical outcomes (VAS score, P = .62; AOFAS score, P = .31; ankle range of motion, P = .31)., Conclusions: Besides the posterior ankle, the anterior compartment of the ankle in the talar neck region was demonstrated to be another potential area for HO after TAA. The development of anterior HO was strongly related to the wide exposure of the cancellous bony surface at the talar neck and therefore occurred more often with the Mobility than with the Hintegra prosthesis., Level of Evidence: Level III, retrospective comparative case series., (© The Author(s) 2016.)

The longitudinal arch is one of the hallmarks of the human foot but its evolutionary history remains controversial due to the fragmentary nature of the fossil record. In modern humans, the presence of a longitudinal arch is reflected in the angular relationships among the major surfaces of the human talus and calcaneus complex, which is also known as the rearfoot. A complete talus and calcaneus of Australopithecus sediba provide the opportunity to evaluate rearfoot posture in an early hominin for the first time. Here I show that A. sediba is indistinguishable from extant African apes in the angular configuration of its rearfoot, which strongly suggests that it lacked a longitudinal arch. Inferences made from isolated fossils support the hypothesis that Australopithecus afarensis possessed an arched foot. However, tali attributed to temporally younger taxa like Australopithecus africanus and Homo floresiensis are more similar to those of A. sediba. The inferred absence of a longitudinal arch in A. sediba would be biomechanically consistent with prior suggestions of increased midtarsal mobility in this taxon. The morphological patterns in talus and calcaneus angular relationships among fossil hominins suggest that there was diversity in traits associated with the longitudinal arch in the Plio-Pleistocene.

Running-related injuries are common and previous research has suggested that the magnitude and/or rate of pronation may contribute to the development of these injuries. Accurately and directly measuring pronation can be challenging, and therefore previous research has often relied on navicular drop (under both static and dynamic conditions) as an indirect assessment of pronation. The objectives of this study were to use dynamic, biplane X-ray imaging to assess the effects of three footwear conditions (barefoot, minimalist shoes, motion control shoes) on the magnitude and rate of navicular drop during running, and to determine the association between static and dynamic measures of navicular drop. Twelve healthy distance runners participated in this study. The magnitude and rate of navicular drop were determined by tracking the 3D position of the navicular from biplane radiographic images acquired at 60Hz during the stance phase of overground running. Static assessments of navicular drop and foot posture were also recorded in each subject. Footwear condition was not found to have a significant effect on the magnitude of navicular drop (p=0.22), but motion control shoes had a slower navicular drop rate than running barefoot (p=0.05) or in minimalist shoes (p=0.05). In an exploratory analysis, static assessments of navicular drop and foot posture were found to be poor predictors of dynamic navicular drop in all footwear conditions (p>0.18)., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Unlabelled: Accurate estimates of tibialis anterior (TA) muscle force are important in many contexts. Two approaches commonly used to estimate moment arms are the tendon excursion (TE) and geometric (GEO) methods. Previous studies report poor agreement between the two approaches., Purpose: The purposes of this study were to 1) assess the effect of methodological variations in the two methods of moment arm estimation and 2) determine how these variations affect agreement between the methods., Methods: TA moment arms were determined using TE and GEO. Errors associated with tendon stretch/hysteresis, talus rotation relative to the foot, and the location of the line of action were investigated., Results: For TE, large errors in moment arm estimates across the range of motion were found when tendon length changes (P = 0.001) were not corrected for. For GEO, the estimated moment arm was reduced at an ankle angle of -15° when discrepancies between talus and foot rotations were accounted for or when an alternative tendon line of action was used either separately (effect size (ES), 0.46 and 0.58, respectively; P > 0.05) or together (ES, 0.89; P > 0.05). TE-derived moment arms were smaller than GEO-derived moment arms (ES, 0.68-4.86, varying by angle) before accounting for sources of error. However, these differences decreased after error correction (ES, 0.09-1.20, P > 0.05). Nonetheless, the shape of the moment arm-joint angle relation was curvilinear for TE but linear for GEO., Conclusions: Of all methodological modifications, accounting for tendon length changes had the largest effect on TA moment arm estimates. We conclude that the TE method is viable to determine TA moment arms as long as changes in tendon length are accounted for.

Context: Altered neuromuscular function and decreased dorsiflexion range of motion (DFROM) have been observed in patients with chronic ankle instability (CAI). Joint mobilizations are indicated for restoring DFROM and dynamic postural control, yet it remains unknown if a mobilization can alter neuromuscular excitability in muscles surrounding the ankle., Objective: To determine the immediate effects of a Maitland grade III anterior-to-posterior joint mobilization on spinal-reflex and corticospinal excitability in the fibularis longus (FL) and soleus (SOL), DFROM, and dynamic postural control., Design: Single-blinded randomized control trial., Setting: Research laboratory., Patients: 30 patients with CAI randomized into a mobilization (n = 15) or control (n = 15) group., Intervention: Maitland grade III anterior-to-posterior joint mobilization., Main Outcome Measures: Spinal-reflex excitability was measured with the Hoffmann reflex, while corticospinal excitability was evaluated with transcranial magnetic stimulation. DFROM was measured seated with the knee extended, and dynamic postural control was quantified with the Star Excursion Balance Test. Separate 2 × 2 repeated-measures ANOVAs were performed for each outcome measure. Dependent t tests were used to evaluate individual differences within groups in the presence of significance., Results: Spinal-reflex and corticospinal excitability of the SOL and FL were not altered in the mobilization or control group (P > .05). DFROM increased immediately after the mobilization (P = .05) but not in the control group, while dynamic postural control was unchanged in both groups (P > .05)., Conclusion: A single joint-mobilization treatment was efficacious at restoring DFROM in participants with CAI; however, excitability of spinal reflex and corticospinal pathways at the ankle and dynamic postural control were unaffected.

Purpose: The purposes of this study were to identify differences in the biomechanical and biochemical properties among the articulating surfaces of the ankle joint and to evaluate the functional and biological properties of engineered neocartilage generated using chondrocytes from different locations in the ankle joint., Methods: The properties of the different topographies within the ankle joint (tibial plafond, talar dome, and distal fibula) were evaluated in 28 specimens using 7 bovine ankles; the femoral condyle was used as a control. Chondrocytes from the same locations were used to form 28 neocartilage constructs by tissue engineering using an additional 7 bovine ankles. The functional properties of neocartilage were compared with native tissue values., Results: Articular cartilage from the tibial plafond, distal fibula, talar dome, and femoral condyle exhibited Young modulus values of 4.8 ± 0.5 MPa, 3.9 ± 0.1 MPa, 1.7 ± 0.2 MPa, and 4.0 ± 0.5 MPa, respectively. The compressive properties of the corresponding tissues were 370 ± 22 kPa, 242 ± 18 kPa, 255 ± 26 kPa, and 274 ± 18 kPa, respectively. The tibial plafond exhibited 3-fold higher tensile properties and 2-fold higher compressive and shear moduli compared with its articulating talar dome; the same disparity was observed in neocartilage. Similar trends were detected in biochemical data for both native and engineered tissues., Conclusions: The cartilage properties of the various topographic locations within the ankle are significantly different. In particular, the opposing articulating surfaces of the ankle have significantly different biomechanical and biochemical properties. The disparity between tibial plafond and talar dome cartilage and chondrocytes warrants further evaluation in clinical studies to evaluate their exact role in the pathogenesis of ankle lesions., Clinical Relevance: Therapeutic modalities for cartilage lesions need to consider the exact topographic source of the cells or cartilage grafts used. Furthermore, the capacity of generating neocartilage implants from location-specific chondrocytes of the ankle joint may be used in the future as a tool for the treatment of chondral lesions., (Copyright © 2014 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

CT-osteoabsorptiometry (CT-OAM) has been used to visualize subchondral bone plate density distribution regarding to its mineralization. The purpose of this study was to display and analyze the density distribution of the subchondral bone plate before and after supramalleolar realignment osteotomies. We retrospectively analysed pre- and postoperative CT images of nine consecutive patients with post-traumatic unilateral valgus ankle OA. The distribution charts of CT-OAM scans were quantitatively analyzed for subchondral bone plate density distribution. VAS for pain and the Tegner activity scale were used to assess clinical outcome. At a mean follow-up of 20 ± 5.6 months (range 13-27), we observed a significant pre- to postoperative decrease of the mean high-density area ratio in tibia (lateral and posterior area) (p ≤ 0.05) and the talus (lateral area) (p ≤ 0.05). Pairwise comparison between the pre- and postoperative mineralization at the articular surface showed a significant decrease of the high-density area ratio for the tibia and the talus. The VAS decreased from 6.2 ± 0.9 pre- to 2.8 ± 0.9 postoperatively (p = 0.027), and the Tegner score inclined from 4.5 ± 1.1 preoperatively to 5.3 ± 0.7 after surgery (p = 0.082). The tibial and talar subchondral bone plate density, regarding to its mineralization, decreased after supramalleolar medial closing wedge osteotomy in patients with valgus ankle OA. The results of this study suggest that realignment surgery may decrease peak bone density areas corresponding to the alignment correction and contribute to a homogenization of the subchondral bone plate mineralization., (© 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Objective: To determine the effects of walking with talus-stabilizing taping (TST) on ankle dorsiflexion (DF) and heel-off time in the stance phase of gait and ankle DF passive range of motion (PROM)., Design: Pre- and post-intervention study., Setting: University motion analysis laboratory., Participants: Ten subjects participated in this study. Sixteen ankles with limited ankle DF PROM were tested., Main Outcome Measures: Ankle DF PROM was measured using a goniometer, and maximum ankle DF before heel-off and time to heel-off in the stance phase of gait were measured using a 3D motion analysis system before and after walking with TST. Data were analyzed using a paired t-test., Results: Ankle maximum DF before heel-off (p = 0.001), time to heel-off during the stance phase of gait (p = 0.005), and ankle DF PROM (p < 0.001) were significantly increased post-intervention compared with pre-intervention., Conclusions: Walking with TST is an effective self-exercise for improving ankle kinematics during gait and increasing ankle DF PROM in individuals with limited ankle DF PROM., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The appositional articular morphology of the talo-crural joint is the third component of the joint complex. It is a site of internal integration of this highly stable functional evolutionary unit. Prior studies of the other two components, tibia and talus, demonstrated that substrate preference influenced their articular shape. This effect was unrelated to physical attributes (size and mass) and phylogeny (superfamily). The effect of this behavioral factor, substrate preference, on shape and integration of the appositional articular morphology was investigated. Two hundred forty-five matched distal tibial and proximal talar landmarked surfaces from 12 diverse Catarrhine taxa were studied. Shape effects due to the same factors previously studied were examined in the tibial and talar subsets and were highly significant (P < 0.0001). These were assessed using Multivariate Regression and Relative Warps analysis, and Permutation tests, with results consistent with prior unmatched cohorts. Substrate preference influenced shape and was unrelated to the other factors across taxa. Singular Warp analysis of the cross-covariance matrix revealed sorting of taxa by substrate use, unrelated to physical attributes and phylogeny. Finally, the sorting demonstrated a signal of convergent evolution among distantly related taxa and divergent evolution among closely related taxa reflecting substrate use. Results were consistent with a behavioral influence, substrate use, affecting articular shape and integration in this highly stable functional evolutionary unit, and signals with evolutionary implications., (Copyright © 2014 Wiley Periodicals, Inc.)

Gorillas occupy a variety of habitats from the west coast to eastern central Africa. These habitats differ considerably in altitude, which has a pronounced effect on forest ecology. Although all gorillas are obligate terrestrial knuckle-walking quadrupeds, those that live in lowland habitats eat fruits and climb more often than do those living in highland habitats. Here we test the hypothesis that gorilla talus morphology falls along a morphocline that tracks locomotor function related to a more inverted or everted foot set. This proposed morphocline predicts that gorillas living in lowland habitats may have a talocrural joint configured to facilitate a more medially oriented foot during climbing, suggesting that they may be more adaptively committed to arboreality than gorillas living in highland habitats. To quantify the relative set of the foot in gorillas, we chose two three-dimensional measurements of the talocrural joint: mediolateral curvature of the trochlea and relative surface area of the lateral malleolus. Our results show that, in comparison to their eastern counterparts, western gorillas have talar features that reflect a more medially directed sole of the foot. This morphology likely facilitates foot placement in a wider range of positions and minimization of shearing stresses across the joint when the foot is loaded on more curved or vertically oriented substrates as occurs during climbing and other arboreal behaviors. In contrast, eastern gorilla talar morphology is consistent with habitual placement of the foot with the sole directed more inferiorly, suggesting more effective loading during plantigrade push-off on terrestrial substrates., (Copyright © 2013 Wiley Periodicals, Inc.)

Objectives: To prospectively compare computed tomography (CT) of the hindfoot in the supine non-weight-bearing position (NWBCT) with upright weight-bearing position (WBCT)., Methods: Institutional review board approval and informed consent of all patients were obtained. NWBCT and WBCT scans of the ankle were obtained in 22 patients (mean age, 46.0 ± 17.1 years; range 19-75 years) using a conventional 64-row CT for NWBCT and a novel cone-beam CT for WBCT. Two musculoskeletal radiologists independently performed the following measurements: the hindfoot alignment angle, fibulocalcaneal and tibiocalcaneal distances, lateral talocalcaneal joint space width, talocalcaneal overlap and naviculocalcaneal distance. Significant changes between NWBCT and WBCT were sought using Wilcoxon signed-rank test. P values <0.05 were considered statistically significant., Results: Significant differences were found for all measurements except the hindfoot alignment angle and tibiocalcaneal distance. Significant measurement results were as follows (NWBCT/WBCT reader 1; NWBCT/WBCT reader 2, mean ± standard deviation): fibulocalcaneal distance 3.6 mm ± 5.2/0.3 mm ± 6.0 (P = 0.006); 1.4 mm ± 6.3/-1.1 mm ± 6.3 (P = 0.002), lateral talocalcaneal joint space width 2.9 mm ± 1.7/2.2 mm ± 1.1 (P = 0.005); 3.4 mm ± 1.9/2.4 mm ± 1.3 (P = 0.001), talocalcaneal overlap 4.1 mm ± 3.9/1.4 mm ± 3.9 (P = 0.001); 4.5 mm ± 4.3/1.4 mm ± 3.7 (P < 0.001) and naviculocalcaneal distance 13.5 mm ± 4.0/15.3 mm ± 4.7 (P = 0.037); 14.0 mm ± 4.4/15.7 mm ± 6.2 (P = 0.100). Interreader agreement was good to excellent (ICC 0.48-0.94)., Conclusion: Alignment of the hindfoot significantly changes in the upright weight-bearing CT position. Differences can be visualised and measured using WBCT., Key Points: • Cone-beam computed tomography (CBCT) offers new opportunities for musculoskeletal problems • Visualization and quantification of hindfoot alignment are possible in upright weight-bearing CBCT • Hindfoot alignment changes significantly from non-weight-bearing to weight-bearing CT • The weight-bearing position leads to a decrease in the fibulocalcaneal distance and talocalcaneal overlap • The naviculocalcaneal distance is increased in the weight-bearing position.

We investigated the existence of a midtarsal joint locking mechanism using cadaveric simulations of normal gait. Previous descriptions of this phenomenon led us to hypothesize that non-coupled rotations of the calcaneocuboid and talonavicular (i.e., midtarsal) joints and cubonavicular and talocalcaneal joints occur at heel strike and during weight acceptance, after which joint rotations cease with all bone-to-bone orientations remaining constant during the latter portions of stance phase. Three-dimensional kinematics of the talus, calcaneus, cuboid, and navicular were recorded along with muscle and ground reaction forces. Finite helical axis parameters and joint angles of directly articulating bones were subsequently derived and examined. During weight acceptance, the midtarsal joints everted with obvious changes in the relative orientation of their helical axes. The relative non-parallel orientation of these axes then remained constant until late in stance when these joints inverted and dorsiflexed toward their original pre-stance orientation. The cubonavicular and talocalcaneal joints demonstrated complimentary behavior. Contrary to our hypothesis, the midtarsal joints remained compliant during foot flat and even more so during push-off, despite divergent joint axes. Joint rotations were present after weight acceptance, thereby challenging the concept that midtarsal joint locking produces a rigid lever during push-off. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:110-115, 2014., (© 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Ankle passive kinematics is determined primarily by articular surface morphology and ligament constraints. Previous morphological studies concluded that the talar dome can be approximated by a truncated cone, whose apex is directed medially and whose major axis is the axis of rotation of the ankle. This and other functional morphology concepts were evaluated in this study whose goal was to describe and quantify the 3D morphology of the talus using 3D image-based bone models and engineering software tools., Methods: CT data from 26 healthy adults were processed to produce 3D renderings of the talus and were followed by morphological measurements including the radii of curvature of circles fitted to the medial and lateral borders of the trochlea and radii of curvature of coronal sections., Findings: The surfaces containing the medial and lateral borders of the trochlea are not parallel and the radius of curvature of the medial border is larger than the lateral border. In the coronal plane the trochlear surface was mostly concave., Interpretation: The trochlear surface can be modeled as a skewed truncated conic saddle shape with its apex oriented laterally rather than medially as postulated by Inman. Such shape is compatible, as opposed to Inman's cone postulate, with the observed pronation/supination and provides stable congruency in movements of inversion/eversion. The results challenge the fundamental theories of functional morphology of the ankle and suggest that these new findings should be considered in future biomechanical research and in clinical applications such as design of total ankle replacements., (© 2013. Published by Elsevier Ltd. All rights reserved.)

Objective: The purpose of this study was to evaluate the effectiveness of demineralized bone matrix (DBM) with and without platelet-rich plasma (PRP) in the treatment of osteochondral defects (OCDs) of the talus. We hypothesized that treatment with DBM would result in more bone formation than no treatment in control OCDs, and that PRP would further enhance the regenerative capacity of DBM., Method: A standardized 6-mm OCD was created in each talus of 16 adult goats. According to a randomization scheme, one OCD of each goat was treated with allogeneic DBM hydrated with normal saline (n = 8) or hydrated with autologous PRP (n = 8). The contralateral OCD (n = 16) served as control. After 24 weeks, the animals were euthanized and the tali excised. Various outcome parameters were analyzed with use of macroscopic evaluation, micro-computed tomography (μCT), histology, histomorphometry, and fluorescence microscopy., Results: None of the analyses revealed statistically significant differences between the groups for any of the parameters analyzed in any volume of interest. For example, the mean bone volume fraction (BV/TV) of the defect, as measured by μCT, was 0.56 (95% confidence interval [CI], 0.44-0.68) for DBM hydrated with normal saline and 0.52 (95% CI, 0.40-0.65) for DBM hydrated with PRP, compared to 0.53 (95% CI, 0.45-0.61) and 0.54 (95% CI, 0.44-0.64) for the internal controls, respectively (P > 0.05)., Conclusion: In contrast to our hypotheses, no beneficial treatment effect of DBM with or without PRP was found for OCDs of the caprine talus., (Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

A variety of methods have been developed to use bovid postcranial elements in the functional morphology approach to paleohabitat prediction. This study represents a first attempt at testing morphometric methods based on astragalus and phalanges on extant mountain-dwelling bovids and insular fossil bovids from Sardinia assigned to the so-called 'Nesogoral group', already regarded as close to the Caprini tribe. We intended to answer the questions whether a classic four-habitats model could be successfully applied to extant mountain-dwelling bovids, and whether results obtained could support the hypothesis of a radiative evolution for the Sardinian bovids. Results obtained, on the one hand, highlighted some inadequacies of the method if not applied to African bovids; on the other hand, they stressed the difficulties of discriminating habitat preferences of Sardinian taxa only based on biometry of astragalus and phalanges. Nonetheless, statistical habitat predictions suggest the contemporaneous presence in Sardinia of bovids having about the same size, but inhabiting different environments, giving support to the hypothesis that Sardinian representatives of the genus Nesogoral originated from a still unknown ancestor by an adaptive radiation evolutionary process., (© 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.)

The distal component of the talo-crural joint, the talus, was compared, using geometric morphometrics, in 219 specimens from nine extant taxa to identify differences in shape and the factors influencing them. The specimens were laser scanned, digitally reconstructed, and landmarked. The whole talus, proximal and distal articular facet subgroups were analyzed using Generalized Procrustes analysis, linear regression, principal component analysis, analysis of percent variance, dot-product vector analysis, and pair-wise permutation tests to evaluate shape, and were visualized by TPS deformation of an exemplar surface. Significant percentages of shape variation among taxa were due to body mass, talar size, superfamily, and substrate preference. Shape and presentational morphology associated with these factors were documented, along with the similarities and differences among individual taxa. Nearly all taxa were significantly different in overall, proximal and distal shapes. The most important factors influencing whole talar shape were log centroid size and substrate preference. Substrate preference was also the most important factor defining proximal articular morphology and unrelated to other factor such as mass, while distal articular morphology was influenced by superfamily (head angle and shape). Results demonstrated that substrate preference and superfamily significantly influenced distal presentation, while substrate preference influenced proximal articular shape., (Copyright © 2013 Wiley Periodicals, Inc.)

Purpose: Certain regions of the talar trochlea are recognized as exhibiting varying cartilage thickness and degrees of subchondral bone mineralization. These changes have been attributed to the long-term loading history. For the current study, we accepted the hypothesis that stress-induced alterations of the joint surface include not only varying degrees of subchondral lamellar mineralization, but also structural changes of the subarticular cancellous bone., Methods: In order to examine the structure of the subarticular cancellous bone, ten formalin-fixed talar trochleae were analyzed using micro CT. Sixteen measurement zones were defined and then evaluated in five layers each of 1-mm thickness, enabling assessment of the cancellous architecture extending 5 mm below the trochlear surface using numerical and structural parameters., Results: As with mineralization patterns in the subchondral lamella, large variation was observed regarding bone volume, trabecular quantity, thickness, and spacing, as well as for structure model index and degree of anisotropy, depending on localization. In addition, like previous reports examining mineralization of the subchondral lamella, two distinct groups could be identified as "bicentric" or "monocentric"., Conclusions: These results show that structural tissue adaptation probably due to loading history is also evident within the subarticular cancellous bone.

The calcaneus is axially loaded at its articular interface with the talus. A large bulk of this load is transmitted to the ground across the non-articular tubercles at the plantar surface of the bone. A small part of the incumbent load sustained by the calcaneus is directed towards the forefoot at the calcaneo-cuboid junction. This study investigates the proportion of load distributed across the articular and non-articular surfaces of the calcaneus. The present study demonstrates strong and significant correlation between some of the load bearing variables and suggests the need for further investigations to understand the effect of angular aspects of axial loading on the calcaneus. Accounting for the relative distribution of weight across the articular and non-articular areas may enable us to appreciate the internal trabecular structure of the calcaneus in light of its clinical importance., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The trabecular structure of the ankle bone in small to medium-bodied (60-5000 g) primates of distinct locomotor types was analyzed using high-resolution X-ray computed tomography. There are large inter-, intraspecific, and regional (medial vs. lateral) variations in the trabecular architecture of the talar body. Body mass has no effect on the bone volume fraction or on the fabric anisotropy. However, both the number and thickness of trabeculae seem to be body mass-dependent. All taxa show anisotropic trabecular bone, but the degree of anisotropy and elongation values vary, notably across the locomotion categories. The fabric orientation in the talar body indicates that, practically, all taxa studied display a generally consistent pattern of orientation restricted primarily to a dorsoplantar direction. We have observed a mediolateral difference in the bone volume fraction in most primates who are proficient or frequent climbers. This could reflect a specific reinforcement of the trabecular structure in response to the loads engendered in habitually sustained foot inversion. In contrast, tali of primates who are proficient or frequent leapers rather exhibit a different three-dimensional distribution of the material, which consists of a more anisotropic trabecular structure. This could reflect stronger unidirectional and stereotypical-loading conditions generated at the ankle joints during a leap. Finally, it appears that the talar trabecular bone structure has a good potential for predicting locomotion in extinct species. We have analyzed the trabecular bone structure of the talus of some Eocene European primates (Adapis, Leptadapis, and Necrolemur) and compared the functional signal of the external versus internal talar anatomy in these fossils., (Copyright © 2012 Wiley Periodicals, Inc.)

This study tested the hypothesis that talar trabecular microarchitecture reflects the loading patterns in the primate ankle joint, to determine whether talar trabecular morphology might be useful for inferring locomotor behavior in fossil hominins. Trabecular microarchitecture was quantified in the anteromedial, anterolateral, posteromedial, and posterolateral quadrants of the talar body in humans and non-human primates using micro-computed tomography. Trabecular bone parameters, including bone volume fraction, trabecular number and thickness, and degree of anisotropy differed between primates, but not in a manner entirely consistent with hypotheses derived from locomotor kinematics. Humans have highly organized trabecular struts across the entirety of the talus, consistent with the compressive loads incurred during bipedal walking. Chimpanzees possess a high bone volume fraction, consisting of plate-like trabecular struts. Orangutan tali are filled with a high number of thin, connected trabeculae, particularly in the anterior portion of the talus. Gorillas and baboons have strikingly similar internal architecture of the talus. Intraspecific analyses revealed no regional differences in trabecular architecture unique to bipedal humans. Of the 22 statistically significant regional differences in the human talus, all can also be found in other primates. Trabecular thickness, number, spacing, and connectivity density had the same regional relationship in the talus of humans, chimpanzees, gorillas, and baboons, suggesting a deeply conserved architecture in the primate talus. Australopithecus tali are human-like in most respects, differing most notably in having more oriented struts in the posteromedial quadrant of the body compared with the posterolateral quadrant. Though this result could mean that australopiths loaded their ankles in a unique manner during bipedal gait, the regional variation in degree of anisotropy was similar in humans, chimpanzees, and gorillas. These results collectively suggest that the microarchitecture of the talus does not simply reflect the loading environment, limiting its utility in reconstructing locomotion in fossil primates., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Previous studies reported the effect of flatfoot deformity on tibiotalar joint contact characteristics. The lateral shift of the load which occurred in flatfeet may be responsible for degenerative changes in the ankle joint. The purpose was to assess the pattern of joint contact stress of the tibiotalar joint in intact, flat, and corrected specimens with subtalar arthroereisis. Seven fresh-frozen cadaver specimens were studied in the intact and flat-footed condition after transection of ligaments which support the medial arch. Ankle joint contact stress and plantar pressure patterns were determined from a capacitive pressure sensor inserted in the tibiotalar joint and a pressure distribution platform when the specimens were axially loaded in simulated mid-stance. Contact pressure was also assessed after subtalar arthroereisis with a 12 mm Kalix implant for correction of the flatfoot deformity. A maximum contact pressure of 1414.2±319.2 kPa was recorded in the middle-medial region in intact specimens. Flatfoot caused a lateral shift in the pressure distribution (p<0.05). In the flat specimens, the maximum contact pressure of 1394.7 8±470.5 kPa was in the anterior-central region. After subtalar arthroereisis with the Kalix implant for correction of the flatfoot deformity a maximum contact pressure of 1323.3±497.5 kPa was observed in the middle-lateral region. In a cadaver model, subtalar arthroereisis with Kalix implant failed to restore a normal intraarticular ankle joint pressure pattern. Further interventions should be considered to restore a normal pressure pattern., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Summary of Background Data: Research on biomechanics of the ankle and foot has demonstrated a complex pattern of load distribution through the ankle joint., Objective: Investigating possible relationship between articular dimensions, angular parameters and overall talar morphology., Methods: Two linear dimensions, six articular surfaces and three angular parameters were measured from dried human talar bones (left=60; right=82). Angular parameters were measured at the neck of the bone (junction of the head and the body). Correlation and co-variation were worked out between the values of surface area parameters and the angular orientations measured from all the samples in context of load transmission across the talus., Results: The total trochlear surface area of the talus totaled approximately equal to the sum of areas at the head and the lower surface of the talus. The vertical angle showed a strong correlation with the articulating surface area below the head of the talus in contact with the spring ligament., Conclusions: Articular surface areas as well as the angular orientations of talar components vary with the magnitude of stress subjected to the bone. The inter-relationship between articular and angular parameters within the talus demonstrates strong correlation for certain parameters., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The calcaneus is a desirable site for harvesting autologous bone for use in foot surgery. However, fracture of the calcaneus is a serious complication associated with bone harvesting from this site. Currently it is unknown how much bone may be safely harvested from the calcaneus without inducing a fracture. The purpose of this study was to investigate the effect of progressive bone removal from the calcaneus onto the mechanical stress redistribution of the foot, and therefore on the increase in fracture risk. Different loads were applied on the talus to evaluate the calcaneus stress distribution at different situations. Because of the potential increase in mechanical stress in the calcaneus, secondary to contraction of the Achilles tendon, we also evaluated the mechanical behavior properties of the foot with increasing traction force in the Achilles tendon. A three-dimensional (3D) finite element (FE) model developed from CT images obtained from a healthy individual was used to compute displacement, tension and compression stresses in six situations, including intact foot, and five depth of the bone block removed, with a maximum depth of 7.5 mm. The results from these simulations indicated that when the maximum load was applied at the Achilles tendon, the tension stress increased from 42.16 MPa in the intact foot to 86.28 MPa with maximum bone harvesting. Furthermore, as the volume of bone extracted from the calcaneus increases, there is a redistribution of stresses that differs significantly from the intact foot. In fact, although the maximum stress was not significantly affected by increasing the volume of bone harvested-except when increasing the Achilles tendon force-, stresses did increase in areas of the calcaneus is vulnerable to injury, leading to an increase in fracture risk., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Shoe-surface interface characteristics have been implicated in the high incidence of ankle injuries suffered by athletes. Yet, the differences in rotational stiffness among shoes may also influence injury risk. It was hypothesized that shoes with different rotational stiffness will generate different patterns of ankle ligament strain. Four football shoe designs were tested and compared in terms of rotational stiffness. Twelve (six pairs) male cadaveric lower extremity limbs were externally rotated 30 deg using two selected football shoe designs, i.e., a flexible shoe and a rigid shoe. Motion capture was performed to track the movement of the talus with a reflective marker array screwed into the bone. A computational ankle model was utilized to input talus motions for the estimation of ankle ligament strains. At 30 deg of rotation, the rigid shoe generated higher ankle joint torque at 46.2 ± 9.3 Nm than the flexible shoe at 35.4 ± 5.7 Nm. While talus rotation was greater in the rigid shoe (15.9 ± 1.6 deg versus 12.1 ± 1.0 deg), the flexible shoe generated more talus eversion (5.6 ± 1.5 deg versus 1.2± 0.8 deg). While these talus motions resulted in the same level of anterior deltoid ligament strain (approxiamtely 5%) between shoes, there was a significant increase of anterior tibiofibular ligament strain (4.5± 0.4% versus 2.3 ± 0.3%) for the flexible versus more rigid shoe design. The flexible shoe may provide less restraint to the subtalar and transverse tarsal joints, resulting in more eversion but less axial rotation of the talus during foot∕shoe rotation. The increase of strain in the anterior tibiofibular ligament may have been largely due to the increased level of talus eversion documented for the flexible shoe. There may be a direct correlation of ankle joint torque with axial talus rotation, and an inverse relationship between torque and talus eversion. The study may provide some insight into relationships between shoe design and ankle ligament strain patterns. In future studies, these data may be useful in characterizing shoe design parameters and balancing potential ankle injury risks with player performance.