Open talus fracture are notoriously difficult to manage and they are commonly associated with a high level of complications including non-union, avascular necrosis and infection. Currently, the management of such injuries is based upon BOAST 4 guidelines although there is no suggested definitive management, thus definitive management is based upon surgeon preference. The key principles of open talus fracture management which do not vary between surgeons, however, there is much debate over whether the talus should be preserved or removed after open talus fracture/dislocation and proceeded to tibiocalcaneal fusion. A review of electronic hospital records for open talus fractures from 2014-2021 returned foureen patients with fifteen open talus fractures. Seven cases were initially managed with ORIF, five cases were definitively managed with FUSION, while the others were managed with alternative methods. We collected patient's age, gender, surgical complications, surgical risk factors and post-treatment functional ability and pain and compliance with BOAST guidelines. The average follow-up of the cohort was four years and one month. EQ-5D-5L and FAAM-ADL/Sports score was used as a patient reported outcome measure. Data was analysed using the software PRISM. Comparison between FUSION and ORIF groups showed no statistically significant difference in EQ-5D-5L score (P = 0.13), FAAM-ADL (P = 0.20), FAAM-Sport (P = 0.34), infection rate (P = 0.55), surgical times (P = 0.91) and time to weight bearing (P = 0.39), despite a higher proportion of polytrauma and Hawkins III and IV fractures in the FUSION group. FUSION is typically used as second line to ORIF or failed ORIF. However, there are a lack of studies that directly compared outcome in open talus fracture patients definitively managed with FUSION or ORIF. Our results demonstrate for the first time, that FUSION may not be inferior to ORIF in terms of patient functional outcome, infection rate, and quality-of-life, in the management of patients with open talus fracture patients. Of note, as open talus fractures have increased risks of complications such as osteonecrosis and non-union, FUSION should be considered as a viable option to mitigate these potential complications in these patients

Abstract. Objectives. The fidelity of a 3D model created using image segmentation must be precisely quantified and evaluated for the model to be trusted for use in subsequent biomechanical studies such as finite element analysis. The bones within the ankle joint vary significantly in size and shape. The purpose of this study was to test the hypothesis that the accuracy and reliability of a segmented bone geometry is independent of the particular bone being measured. Methods. Computed tomography (CT) scan data (slice thickness 1 mm, pixel size 808±7 µm) from three anonymous patients was used for the development of the ankle geometries (consisting of the tibia, fibula, talus, calcaneus, and navicular bones) using Simpleware Scan IP software (Synopsys, Exeter, UK). Each CT scan was segmented 4 times by an inexperienced undergraduate, resulting in a total of 12 geometry assemblies. An experienced researcher segmented each scan once, and this was used as the ‘gold standard’ to quantify the accuracy. The solid bone geometries were imported into CAD software (Inventor 2023, Autodesk, CA, USA) for measurement of the surface area and volume of each bone, and the distances between bones (tibia to talus, talus to navicular, talus to calcaneus, and tibia to fibula) were carried out. The intra-class coefficient (ICC) was used to assess intra-observer reliability. Bland Altman plots were employed as a statistical measure for criteria validity (accuracy) [1]. Results. The average ICC score was 0.93, which is regarded as a high reliability score for an inexperienced user. The talus to navicular and talus to tibia separations, which had the smallest distances, showed a slight decrease in reliability and this was observed for all separations shorter than 2 mm. According to the Bland-Altman plots, more than 95% of the data points were inside the borders of agreement, which is an excellent indication of accuracy. The bias percentage (average error percentage) varied between 1% and 4% and was constant across all parameters, with the proportion rising for short distance separations. Conclusions. The current study demonstrates that an inexperienced undergraduate, with access to software manuals, can segment an ankle CT scan with excellent reliability. The present study also concluded that all five bones were segmented with high levels of accuracy, and this was not influenced by bone volume or type. The only factor found to influence the reliability was the magnitude of distance between bones, where if this was smaller than 2 mm it reduced the reliability, indicating the influence of CT scan resolution on the segmentation reliability. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

A medializing calcaneal osteotomy (MCO) is one of the key inframalleolar osteotomies to correct progressive collapsing foot deformity (PCFD). While many studies were able to determine the hind- and midfoot alignment after PCFD correction, the subtalar joint remained obscured by superposition on plain radiography. Therefore, we aimed to perform a 3D measurement assessment of the hind- and subtalar joint alignment pre- compared to post-operatively using weightbearing CT (WBCT) imaging. Fifteen patients with a mean age of 44,3 years (range 17-65yrs) were retrospectively analyzed in a pre-post study design. Inclusion criteria consisted of PCFD deformity correct by MCO and imaged by WBCT. Exclusion criteria were patients who had concomitant midfoot fusions or hindfoot coalitions. Image data were used to generate 3D models and compute the hindfoot - and talocalcaneal angle as well as distance maps. Pre-operative radiographic parameters of the hindfoot and subtalar joint alignment improved significantly relative to the post-operative position (HA, MA. Sa. , and MA. Co. ). The post-operative talus showed significant inversion, abduction, and dorsiflexion of the talus (2.79° ±1.72, 1.32° ±1.98, 2.11°±1.47) compared to the pre-operative position. The talus shifted significantly different from 0 in the posterior and superior direction (0.62mm ±0.52 and 0.35mm ±0.32). The distance between the talus and calcaneum at the sinus tarsi increased significantly (0.64mm ±0.44). This study found pre-dominantly changes in the sagittal, axial and coronal plane alignment of the subtalar joint, which corresponded to a decompression of the sinus tarsi. These findings demonstrate the amount of alternation in the subtalar joint alignment that can be expected after MCO. However, further studies are needed to determine at what stage a calcaneal lengthening osteotomy or corrective arthrodesis is indicated to obtain a higher degree of subtalar joint alignment correction

Flat-top talus (FTT) is a complication well-known to those treating clubfoot. Despite varying anecdotal opinions, its association with different treatments, especially the Ponseti method, remains uncertain. This systematic review aimed to establish the aetiology and prevalence of FTT, as well as detailing management strategies and their efficacy. A systematic review was conducted according to PRISMA guidelines to search for articles using MEDLINE, EMBASE and Web of Science until November 2021. Studies with original data relevant to one of three questions were included: 1) Possible aetiology 2) Prevalence following different treatments 3) Management strategies and their outcomes. 32 original studies were included, with a total of 1473 clubfeet. FTT may be a pre-existing feature of the pathoanatomy of some clubfeet as well as a sequela of treatment. It can be a radiological artefact due to positioning or other residual deformity. The Ponseti method is associated with a higher percentage of radiologically normal tali (57%) than both surgical methods (52%) and non-Ponseti casting (29%). Only one study was identified that reported outcomes after surgical treatment for FTT (anterior distal tibial hemiepiphysiodesis). The cause of FTT remains unclear. It is seen after all treatment methods but the rate is lowest following Ponseti casting. Guided growth may be an effective treatment. Key words:. Clubfoot, Flat-top talus, Ponseti method, guided growth. Disclosures: The authors have no relevant disclosures

Abstract. Objectives. This abstract provides an update on the Open Ankle Models being developed at the University of Bath. The goal of this project is to create three fully open-source finite element (FE) ankle models, including bones, ligaments, and cartilages, appropriate musculoskeletal loading and boundary conditions, and heterogeneous material property distribution for a standardised representation of ankle biomechanics and pre-clinical ankle joint analysis. Methods. A computed tomography (CT) scan data (pixel size of 0.815 mm, and slice thickness of 1 mm) was used to develop the 3D geometry of the bones (tibia, talus, calcaneus, fibula, and navicular). Each bone was given the properties of a heterogeneous elastic material based on the CT greyscale. The density values for each bone element were calculated using a linear empirical relation, ρ= 0.0405 + (0.000918) HU and then power law equations were utilised to get the Young's Modulus value for each bone element [1]. At the bone junction, a thickness of cartilage ranging from 0.5–1 mm, and was modelled as a linear material (E=10 MPa, ν=0.4 [2]). All ligament insertions and positions were represented by four parallel spring elements, and the ligament stiffness and material attributes were applied in accordance with the published literature [2]. The ankle model was subjected to static loading (balance standing position). Four noded tetrahedral elements were used for the discretization of bones and cartilages. All degrees of freedom were restricted at the proximal ends of the tibia and fibula. The ground reaction forces were applied at the underneath of the calcaneus bone. The interaction between the cartilages and bones was modelled using an augmented contact algorithm with a sliding elastic contact between each cartilage. A tied elastic contact was used between the cartilages and the bone. FEbio 2.1.0 (University of Utah, USA) was used to construct the open-source ankle model. Results. When the double-legged stance phase loading condition was taken into consideration, stress at the antero-medial tibial wall (ranged from 1 to 7 MPa) was found to be similar to the prior work [2], indicating bulk of the load transfer was through this region. The maximum principal strain was predicted at the different regions on bones around the ankle joint. The proximal surface of the talus, and tibial distal surface were shown to have the highest maximum principal strains followed by antero-medial walls of the tibia bone, at the proximal location. Conclusions. The present open 3D FE model of the ankle will assist researchers in better understanding ankle biomechanics, precisely predicting load transfer, and examining the ankle to address unmet clinical needs for this joint. The results of the current investigation are realistic in terms of load transfer and stress-strain distribution across the ankle joint and well comparable to those reported in the literature [2]. However, sensitivity and ankle instability simulations will be performed in future work to investigate the model's reliability and robustness. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. OBJECTIVE. Flattening of the talar dome is observed clinically in haemarthropathy as structural and functional changes advance but has not been quantified yet. In order to confirm clinical observation, and assess the degree of change, morphological measurements were derived from MR images. METHODS. Four measurements were taken, using ImageJ (1.52v), from sagittal MRI projections at three locations – medial, lateral and central: Trochlear Tali Arc Length (TaAL), Talar Height (TaH), Trochlear Tali Length (TaL), and Trochlear Tali Radius (TaR). These measurements were used to generate three ratios of interest: TaR:TaAL, TaAL:TaL, and TaL:TaH. With the hypothesis of a flattening of the talar dome with haemarthropathy, it was expected that TaR:TaAL and TaL:TaH should be greater for haemophilic ankles, and TaAL:TaL should be smaller. A total of 126 MR images (ethics: MEEC 18–022) were included to assess the difference in those ratios between non-diseased ankles (33 images from 11 volunteers) and haemophilic ankles (93 images from 8 patients’ ankles). Non-diseased control measurements were compared to literature to assess the capacity of doing measurements on MRI instead of radiographs or CT. RESULTS. Reasonable agreement was found between measurements on non-diseased ankles and those from literature, with greatest variance in TaAL. The medial talus demonstrated decreases in all dimensions with haemophilia (TaR=2.4%, TaL=14.7%, TaAL=19.5% and TaH=27.8%; t-test at p<0.05), as did the lateral talus (TaR=6.2%, TaL=6.8%, TaAL=12.0% and TaH=22.4%; t-test at p<0.05). The effect on the central talus was not significant. TaAL:TaL showed talar flattening in the medial and lateral haemophilic talus (healthy medial=1.21, lateral=1.20; haemophilic medial=lateral=1.14). CONCLUSION. The results demonstrate non-uniform increased influence of haemarthropathy at the medial and lateral talar extremes, with relatively healthy measurements seen in the centre. The degree of morphological change is however progressive, differing with each haemophilic ankle. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Background. Tibiotalocalcaneal (TTC) fusion is indicated for severe arthritis, failed ankle arthroplasty, avascular necrosis of talus and as a salvage after failed ankle fixation. Patients in our study had complex deformities with 25 ankles having valgus deformities (range 50–8 degrees mean 27 degrees). 12 had varus deformities (range 50–10 degrees mean 26 degrees) 5 ankles an accurate measurement was not possible on retrospective images. 10 out of 42 procedures were done after failed previous surgeries and 8 out of 42 had talus AVN. Methods. Retrospective case series of patients with hindfoot nails performed in our centre identified using NHS codes. Total of 41 patients with 42 nails identified with mean age of 64 years. Time to union noted from X-rays and any complications noted from the follow-up letters. Patients contacted via telephone to complete MOXFQ and VAS scores and asked if they would recommend the procedure to patients suffering similar conditions. 17 patients unable to fill scores (5 deceased, 4 nails removed, 2 cognitive impairment and 6 uncontactable). Results. In our cohort 33/38 of hindfoot nails achieved both subtalar and ankle fusion in a mean time of 7 months. 25 patients with 26 nails had mean follow up with post op scores of 4 years. Their Mean MOXFQ scores were (Pain: 12.8 Walking: 12 Social: 8) and visual analogue pain score was 3. 85% of patients wound recommend this surgery for a similar condition. 20 complications with 15 requiring surgery(5 screw removals, 1 percutaneous drilling, 1 fusion site injection, 8 nail revisions). Conclusion. In our experience hindfoot nail TTC fusion reliably improves the function of patients with severe symptoms in a variety of pathophysiological conditions and complex deformities. Most of our patients would recommend this procedure. There is a lack of studies with long-term follow-up

Total ankle replacement (TAR) is contraindicated in patients with significant talar collapse due to AVN and in these patients total talus body prosthesis has been proposed to restore ankle joint. To date, five studies have reported implantation of a custom-made talar body in patients with severely damaged talus, showing the limit of short-term damage of tibial and calcaneal thalamic joint surfaces. Four of this kind of implants have been performed. The first two realized with “traditional” technology CAD-CAM has been performed in active patients affected by “missing talus” and now presents a survival follow-up of 15 and 17 years. For the third patient affected by massive talus AVN we designed a 3D printed porous titanium custom talar body prosthesis fixed on the calcaneum and coupled with a TAR, first acquiring high-resolution 3D CT images of the contralateral healthy talus that was “mirroring” obtaining the volume of fractured talus in order to provide the optimal fit. Then the 3D printed implant was manufactured. The fourth concern a TAR septic mobilization with high bone loss of the talus. The “two-stage” reconstruction conducted with the implant of total tibio-talo-calcaneal prosthesis “custom made” built with the same technology 3D, entirely in titanium and using the “trabecular metal” technology for the calcaneous interface. Weightbearing has progressively allowed after 6 weeks. No complications were observed. All the implants are still in place with an overall joint mobility ranging from 40° to 60°. This treatment requires high demanding technical skills and experience with TAR and foot and ankle trauma. The 15 years survival of 2 total talar prosthesis coupled to a TAR manufactured by a CAD-CAM procedure encourages consider this 3D printed custom implant as a new alternative solution for massive AVN and traumatic missing talus in active patients

Varus ankle osteoarthritis (OA) is typically associated with peritalar instability, which may result in altered subtalar joint position. This study aimed to determine the extent to which total ankle replacement (TAR) in varus ankle OA can restore the subtalar position alignment using 3-dimensional semi-automated measurements on WBCT. Fourteen patients (15 ankles, mean age 61) who underwent TAR for varus ankle OA were retrospectively analyzed using semi- automated measurements of the hindfoot based on pre-and postoperative weightbearing WBCT (WBCT) imaging. Eight 3-dimensional angular measurements were obtained to quantify the ankle and subtalar joint alignment. Twenty healthy individuals were served as a control groups and were used for reliability assessments. All ankle and hindfoot angles improved between preoperative and a minimum of 1 year (mean 2.1 years) postoperative and were statistically significant in 6 out of 8 angles (P<0.05). Values The post-op angles were in a similar range to as those of healthy controls were achieved in all measurements and did not demonstrated statistical difference (P>0.05). Our findings indicate that talus repositioning after TAR within the ankle mortise improves restores the subtalar position joint alignment within normal values. These data inform foot and ankle surgeons on the amount of correction at the level of the subtalar joint that can be expected after TAR. This may contribute to improved biomechanics of the hindfoot complex. However, future studies are required to implement these findings in surgical algorithms for TAR in prescence of hindfoot deformity

Abstract. Objectives. The syndesmosis joint, located between the tibia and fibula, is critical to maintaining the stability and function of the ankle joint. Damage to the ligaments that support this joint can lead to ankle instability, chronic pain, and a range of other debilitating conditions. Understanding the kinematics of a healthy joint is critical to better quantify the effects of instability and pathology. However, measuring this movement is challenging due to the anatomical structure of the syndesmosis joint. Biplane Video Xray (BVX) combined with Magnetic Resonance Imaging (MRI) allows direct measurement of the bones but the accuracy of this technique is unknown. The primary objective is to quantify this accuracy for measuring tibia and fibula bone poses by comparing with a gold standard implanted bead method. Methods. Written informed consent was given by one participant who had five tantalum beads implanted into their distal tibia and three into their distal fibula from a previous study. Three-dimensional (3D) models of the tibia and fibula were segmented (Simpleware Scan IP, Synopsis) from an MRI scan (Magnetom 3T Prisma, Siemens). The beads were segmented from a previous CT and co-registered with the MRI bone models to calculate their positions. BVX (125 FPS, 1.25ms pulse width) was recorded whilst the participant performed level gait across a raised platform. The beads were tracked, and the bone position of the tibia and fibula were calculated at each frame (DSX Suite, C-Motion Inc.). The beads were digitally removed from the X-rays (MATLAB, MathWorks) allowing for blinded image-registration of the MRI models to the radiographs. The mean difference and standard deviation (STD) between bead-generated and image-registered bone poses were calculated for all degrees of freedom (DOF) for both bones. Results. The absolute mean tibia and fibula bone position differences (Table 1) between the bead and BVX poses were found to be less than 0.5 mm for both bones. The bone rotation differences were found to be less than 1° for all axes except for the fibula Z axis rotation which was found to be 1.46°. One study. 1. has reported the kinematics of the syndesmosis joint and reported maximum ranges of motion of 9.3°and translations of 3.3mm for the fibula. The results show that the accuracy of the methodology is sufficient to quantify these small movements. Conclusions. BVX combined with MRI can be used to accurately measure the syndesmosis joint. Future work will look at quantifying the accuracy of the talus to provide further understanding of normal ankle kinematics and to quantify the kinematics across a healthy population to act as a comparator for future patient studies. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. The aim of this work was to compare the different techniques and the different fluid permeability of the tissue following each technique through assessing the flow of radiopaque contrast agent using μCT image analysis and 3D modelling. Methods. Donated human tali specimens (n=12) were prepared through creating a 10mm diameter chondral defect in three different regions of each talus. Each region then underwent one of three surgical techniques: 1) Fine wire drilling, 2) Nanofracture or 3) Microfracture, equidistant sites in each defect to ensure even distribution. Each region then had an addition of 0.1 ml radiopaque contrast agent (Omnipaque™ 300), imaged using a clinical μCT scanner (SCANCO Medical AG, 73.6 μm resolution). Each μCT scan was segmented using Slicer 3D software (The Slicer Community, 2023 3D Slicer (5.2.2)). The segmentation package was used to segment the bone and contrast agent regions in each different surgical site of each sample. Each defect site was created into a cylinder and the ratio of segmented pixels of contrast agent against bone. Results. The μCT analysis indicated that across the 12 samples, eight nanofracture regions demonstrated flow of the contrast agent either to the depth of the fracture site or deeper. Some lateral flow was also observed in these sites. eight microfracture regions demonstrated that the flow of the contrast agent was localised to the fracture site and a preferential flow laterally. In only one sample, did a fine wire drilling region demonstrate any fluid flow. In this sample, contrast agent had permeated through the drilling site to the bottom and some sub-site permeation was observed. However, in all samples that showed no permeation of contrast agent through the fracture site, a layer of contrast agent on the chondral surface or minor permeation through to the sub-chondral surface. Segmentation of each sample site showed a significant increase (n=12, p<0.05) in fluid flow of the contrast agent in the nanofracture sites (11%) compared to microfracture (5%) and fine wire drilling (2%). Conclusions. Nanofracture showed significantly improved fluid permeability throughout the surrounding trabecular structure, when compared to microfracture and fine wire drilling. Microfracture appears to allow some fluid flow, but only confined to the immediate area around the fracture site, while fine wire drilling appears to allow a comparably small amount, if not no fluid flow through the surrounding trabecular tissue. This conclusion is reinforced by previous literature that concluded the damage to the structure of the trabecular tissue is reduced when using nanofracture, compared to the other two techniques. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Abstract. OBJECTIVES. Valgus high tibial osteotomy (HTO) represents an effective treatment for patients with medial compartment osteoarthritis (OA) in a varus knee. However, the mechanisms which cause this clinical improvement are unclear. Previous studies suggest a wider stance gait can reduce medial compartment loading via reduction in the external knee adduction moment (KAM); a measure implicated in progression of medial compartment OA. This study aimed to measure whether valgus HTO is associated with a postoperative increase in static stance width. METHODS. 32 patients, recruited in the Biomechanics and Bioengineering Centre Versus Arthritis HTO study, underwent valgus (medial opening wedge) HTO. Weightbearing pre- and post- operative radiographs were taken showing both lower limbs. The horizontal distance, measured from a fixed point on the right talus to the corresponding point on the left, was divided by the talus width to give a standardised “stance width” for each radiograph. The difference between pre- and post- operative stance width was compared for each patient using a paired sample t-test. RESULTS. Preoperatively, mean stance was 4.00 talar-widths but postoperatively this increased to 5.41. This mean increase of 1.42 talar-widths was statistically significant (p=0.001) and represents a mean proportional increase in stance width of 35.5% following HTO. Of the 32 patients, 23 showed increased stance width and 9 decreased (range −4.64 to 6.00 talar-widths). CONCLUSIONS. These findings indicate an association of frontal plane surgical realignment at the proximal tibia via a medial opening wedge HTO with an increased stance width on postoperative radiographs. Considering both wider stance gait and HTO have been shown to affect the progression of medial compartment OA, these results may explain one mechanism contributing to the efficacy of HTO surgery. However, the range of changes in stance width suggests significant variability in how patients adapt at a whole-limb and whole-body level following HTO. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. The aim of this study was to develop an open-source finite element model of the ankle for identification of the best clinical treatment to restore stability to the ankle after injury. Methods. The ankle geometry was defined from the Visible Human Project Female CT dataset available from the National Library of Medicine, and segmented using Dragonfly software (Object Research Systems, 2020). The finite element model was created with FEBio (University of Utah, 2021) using the dynamic nonlinear implicit solver. Linear isotropic material properties were assigned to the bones (E=7300MPa, ν=0.3, ρ=1730kg/m. 3. ) and cartilage (E=10MPa, ν=0.4, ρ=1100kg/m. 3. ). Spring elements were used to represent the ligaments and material properties were taken from Mondal et al. [1]. Lagrangian contact was defined between the cartilaginous surfaces with μ=0.003. A standing load case was modelled, assuming even distribution of load between the feet. A reaction force of 344.3N was applied to the base of the foot, a muscle force of 252.2N, and the proximal ends of the tibia and fibula were fully constrained. Results. The von Mises stresses closely matched those reported by Mondal et al. for the fibula (Present study: 1.00MPa, Mondal: 1.30MPa) and the talus (Present study: 2.20MPa, Mondal: 2.39MPa). However stresses within the tibia were underpredicted (Present study: 1.08MPa, Mondal: 5.86MPa). This was because the present study modelled a shorter tibial length because of a limitation in the CT slices available, which reduced the bending force. Conclusions. This first step in producing an open source ankle model for the orthopaedics community has shown the potential of the model to generate results comparable with those found in the literature. Future work is underway to examine the robustness of the model under different loading and explore alternative open-source CT datasets. [1] Mondal, S., & Ghosh, R. (2017). J Orthopaedics, 14(3), 329–335. . https://doi.org/10.1016/j.jor.2017.05.003

Primary bone tumours of the talus are rare. Currently the existing literature is limited to a single case series and case reports or cases described in series of foot tumours. Information regarding the patient's demographics and tumour types is therefore limited. The aim of this study was to investigate these questions and also suggest a management protocol for suspected primary bone tumours of the talus. We retrospectively reviewed the Scottish Bone Tumour Register from January 1954 to May 2010 and included all primary bone tumours of the talus. We identified only twenty three bone tumours over fifty six years highlighting the rarity of these tumours. There were twenty benign and three malignant tumours with a mean age of twenty eight years. A delay in presentation was common with a mean time from onset of symptoms to diagnosis of ten months. Tumour types identified were consistent with previous literature. We identified cases of desmoplastic fibroma and intraosseous lipodystrophy described for the first time. We suggest an investigatory and treatment protocol for patients with a suspected primary bone tumour of the talus. This is the largest series of primary bone tumours of the talus in the literature

The arterial supply of the talus has been extensively studied in the past but there is a paucity of information on the arterial supply to the navicular and a very limited understanding of the intra-osseous supply to the surface of either of these bones. This is despite the likely importance of this supply in relation to conditions such as osteochondral lesions of the dome of the talus, and avascular necrosis and stress fracture of the navicular. Using cadaveric limbs, dissection of the source vessels was performed followed by arterial injection of latex. The talus and navicular were then removed en bloc, preserving the integrity of the injected arterial vasculature. The specimens were then processed using a new, accelerated diaphanisation technique. This rendered the tissue transparent, allowing the injected vessels to be visualised and then mapped onto a 3D virtual reconstruction of the bone. The vasculature to the subchondral surfaces of the talus and navicular, and the source vessel entry points that provide arterial supply into the navicular were identified. This study gives quantifiable evidence of the areas of consistently poor blood supply which may help explain the clinical pattern of talar and navicular pathology. It also provides as yet unpublished information on the arterial supply of the human navicular bone

Osteonecrosis is a potentially devastating condition with poorly defined pathogenesis that can affect several anatomical areas with or without a previous traumatic insult. Post traumatic osteonecrosis (PON) in the foot and ankle has been commonly described in the talus and navicular but rarely in the distal tibia. PON of the distal tibia is a rarely reported and infrequent complication of fracture dislocations of the ankle. Its scarcity can lead to misdiagnosis and inappropriate management due to a lack of clinical knowledge or suspicion with resultant severe functional compromise. We aim to highlight the clinical and radiological features of PON of the distal tibia and report the findings in a series of four patients following a fracture dislocation of the ankle. Three patients sustained a SER4 fracture dislocation and one patient sustained a PER4 fracture dislocation in keeping with standard patterns of injury seen in most trauma units. In each case, PON of the distal tibia presented with progressive anterolateral tibial plafond collapse and valgus deformity of the ankle. The radiological features previously reported in the literature are based on plain film x-ray, CT and MRI but no description of SPECT-CT findings. One of the patients in the series underwent SPECT-CT following clinical suspicion of PON and thus we describe the findings not previously reported. Our objective is to highlight this rare condition as a potential cause for ongoing pain following fracture dislocation of the ankle as well as advocating the use of SPECT/CT as a useful imaging modality to aid in the diagnosis

Osteochondral lesions (OCLs) of the talus are a challenging and increasingly recognized problem in chronic ankle pain. Many novel techniques exist to attempt to treat this challenging entity. Difficulties associated with treating OCLs include lesion location, size, chronicity and problems associated with potential graft harvest sites. Matrix associated stem cell transplantation (MAST) is one such treatment described for larger lesions >15mm. 2. or failed alternative therapies. This cohort study describes a 5 year review of the outcomes of talar lesions treated with MAST. A review of all patients treated with MAST by a single surgeon was conducted. Pre-operative radiographs, MRIs and FAOS outcome questionnaire scores were conducted. Intraoperative classification was conducted to correlate with imaging. Post-operative outcomes included FAOS scores, return to sport, revision surgery/failure of treatment and progression to arthritis/fusion surgery. 32 patients were identified in this cohort. There were 10 females, 22 males, with an average age of 35. 01. 73% had returned and continued playing active sport. 23 patients underwent MAST in the setting of a failed previous operative attempt, with just 9 having MAST as a first option. 9 patients out of 32 had a further procedure. Two patients had a further treatment directed at their OCL. Two patients had a fusion, 2 had a cheilectomy at > 4 years for impingement, one had a debridement of their anterolateral gutter, one had debridement for arthrofibrosis, one patient had a re alignment calcaneal osteotomy with debridement of their posterior tibial tendon. MAST has demonstrated positive results in lesions which prove challenging to treat, even in a “failed microfracture” cohort

Whilst lateral ankle sprain is often considered a benign injury it represents between 3–5% of all A&E visits in the UK. The mechanical characteristics of ankle ligaments under sprain-like conditions are scarcely reported. The lateral collateral ankle ligaments were dissected from n=6 human cadaveric specimens to produce individual bone-ligament-bone specimens. An Instron Electropuls E10000 was used to uni-axially load the ankle ligaments in tension. The ligaments were first preconditioned between 2 N and a load value corresponding to 3.5% strain for 15 cycles and then strained to failure at a rate of 100%/s. The mean ultimate failure loads and their standard deviations for the anterior talofibular (ATFL), calcaneofibular (CFL) and posterior talofibular (PTFL) ligaments are 351.4±105.6 N, 367.8±76.1 N and 263.6±156.6 N, respectively. Whilst the standard deviation values are high they align with those previously reported for ankle ligament characterisation. The large standard deviations are partly due to the inherent variability of human cadaveric tissue but could also be due to varying previous activity levels of participants or a prior unreported ankle sprain. Although the sample size is relatively small the results were stratified to identify any potential correlations of age, BMI and weight with ultimate load. A strong Pearson correlation (r=0.919) was found between BMI and ultimate load of the CFL but a larger sample size is required to confirm a link. The ligament failure modes were observed and categorised as avulsion or intra-ligamentous failure. The ATFL avulsed from the fibula in five instances and intra-ligamentous failure occurred once. The CFL avulsed from the fibula twice and failed four times through intra-ligamentous failure. Finally, the PTFL avulsed from the fibula once, avulsed from the talus once and failed through intra-ligamentous failure in four instances. The results identify the forces required to severely sprain the lateral collateral ankle ligaments and their failure modes

Summary Statement. The current study introduced the effects of projection errors on ankle morphological measurements using CT-based simulated radiographs by correlation analysis between 2D/3D dimensions and reliability analysis with randomised perturbations while measuring planar parameters on radiographs. Introduction. Clinical success of total ankle arthroplasty (TAA) depends heavily on the available anatomy-based information of the morphology for using implants of precisely matched sizes. Among the clinically available medical imaging modalities, bi-planar projective radiographs are commonly used for this purpose owing to their convenience, low cost, and low radiation dose compared with other modalities such as MRI or CT. However, the intrinsic articular surface of the ankle joint is not symmetrical and oblique which implies that it is difficult to describe all the anatomical dimensions in detail with only one radiograph, thereby hindering the determination of accurate ankle morphometric parameters. The purposes of this study were to compare the measurements of ankle morphology using 3D CT images with those on planar 2D images; and to quantify the repeatability of the 2D measurements under simulated random perturbations. Patients & Methods. Fifty-eight fresh frozen cadaveric ankle specimens were used in the current study. Each specimen was fixed in the neutral position with a plastic frame. After fixation, the specimen-fixation construct was scanned using a 16-slice spiral CT scanner (GE BrightSpeed 16, C&G Technologies, USA) with a slice thickness of 0.625 mm. A global coordinate system was embedded in the ankle specimen with the origin at the geometric center of the talus, the anteroposterior (A/P) axis in parallel to the base-plate, the superoinferior (S/I) axis perpendicular to the base-plate, and the mediolateral (M/L) axis as the line perpendicular to both the A/P and S/I axes. Fourteen 3D morphological parameters were automatically determined using a house-developed program in MATLAB R2010a (The MathWorks, Inc., USA). A simulated standard digital radiography system, in which the X-ray focus was 1 meter away from the image plane, was also introduced to determine the planar 2D morphological parameters for comparing with those determined in 3D. Reliability with randomised perturbations during measurements was also assessed in terms of the intra-class correlation coefficients using a 2-way mixed-effects average model (ICC3, k) for intra-examiner assessments. All statistical analysis was performed using SPSS 13.0 (SPSS Inc., USA). Results. Most of the morphological parameters had high correlation and reliability, except for the maximal tibial thickness (MTiTh), distance between most vertex of tibial mortise to the level of MTiTh (MDV) and radius of trochlea tali (TaR) had moderate to low correlation which were 0.54, 0.37 and 0.09 respectively. The ICC coefficients indicated that the MDV, talus width (TaW) and inclination angle between two most vertex points of trochlea tali (MLATa) had moderate and poor reliability which were 0.59, 0.49 and 0.07 respectively. Discussion/Conclusion. The current study introduced the effects of projection errors on ankle morphological measurements using CT-based simulated radiographs by correlation analysis between 2D/3D dimensions and reliability analysis with randomised perturbations while measuring planar parameters on radiographs. MTiTh and MDV are the important parameters to help surgeon pre-surgical decision-making. TaW is one of the critical parameters for choosing accurate sise of TAA implant. It implies that the respectively accurate pose of ankle is critical during bi-planar radiography

To study the effect of ligament injuries and surgical repair we investigated the three-dimensional kinematics of the ankle joint complex and the talocrural and the subtalar joints in seven fresh-frozen lower legs before and after sectioning and reconstruction of the ligaments. A foot movement simulator produced controlled torque in one plane of movement while allowing unconstrained movement in the remainder. After testing the intact joint the measurements were repeated after simulation of ligament injuries by cutting the anterior talofibular and calcaneofibular ligaments. The tests were repeated after the Evans, Watson-Jones and Chrisman-Snook tenodeses. The range of movement (ROM) was measured using two goniometer systems which determined the relative movement between the tibia and talus (talocrural ROM) and between the talus and calcaneus (subtalar ROM). Ligament lesions led to increased inversion and internal rotation, predominantly in the talocrural joint. The reconstruction procedures reduced the movement in the ankle joint complex by reducing subtalar movement to a non-physiological level but did not correct the instability of the talocrural joint