Introduction. Deformity of knee joint causes deviation of mechanical axis in the coronal plane, and the mechanical axis deviation also could adversely affect biomechanics of the ankle joint as well as the knee joint. Particularly, most of the patients undergoing total knee arthroplasty (TKA) have significant preoperative varus malalignment which would be corrected after TKA, the patients also may have significant changes of ankle joint characteristics after the surgery. This study aimed 1) to examine the prevalence of coexisting ankle osteoarthritis (OA) in the patients undergoing TKA due to varus knee OA and to determine whether the patients with coexisting ankle OA have more varus malalignment, and 2) to evaluate the changes of radiographic parameters for ankle joint before and 4 years after TKA. Methods. We evaluated 153 knees in 86 patients with varus knee OA who underwent primary TKA. With use of standing whole-limb anteroposterior radiographs and ankle radiographs before and 4 years after TKRA, we assessed prevalence of coexisting ankle OA in the patients before TKA and analyzed the changes of four radiographic parameters before and after TKA including 1) the mechanical tibiofemoral angle (negative value = varus), 2) the ankle joint orientation relative to the ground (positive value = sloping down laterally), 3) ankle joint space, and 4) medial clear space. Results. Of the 153 knees, 59 (39%) had radiographic ankle OA. The knees with ankle OA had significantly more varus mechanical tibiofemoral angle preoperatively than those without ankle OA (− 11.9° vs. − 9.3° on average, respectively; P = 0.003). Compared to the preoperative condition, the ankle joint orientation relative to the ground significantly changed after TKA (from 9.0° to 4.8° on average, P<0.001) while ankle joint space and medial clear space did not. Conclusions. Our study revealed that coexisting ankle OA would be common in patients with varus knee OA, particularly in patients with more varus malalignment. TKA also significantly changes the ankle joint orientation relative to the ground which shows more parallel to the ground. However, its effect on ankle joint space and medial clear space seems to be minimal upto 4 years after TKA. Our findings warrant consideration in preoperative evaluations of ankle OA in varus knee OA patients undergoing TKA, and further studies should evaluate prospectively the clinical implications of radiographic change of the ankle joint after TKA

Background. Total Ankle Replacement (TAR) has become a common surgical procedure for severe Osteoarthritis of the ankle. Unlike hip and knee, current TARs still suffer from high failure rates. A key reason could be their non-anatomical surface geometry design, which may produce unnatural motion and load-transfer characteristics. Current TARs have articular surfaces that are either cylindrical or truncated cone surfaces following the Inman truncated cone concept from more than 60 years ago [1]. Our recent study demonstrated, that the surfaces of the ankle can be approximated by a Saddle-shaped, Skewed, truncated Cone with its apex directed Laterally (SSCL) [2]. This is significantly different than the surface geometry used in current TAR systems. The goal of this study was to develop and test the reliability of an in vitro procedure to investigate the effect of different joint surface morphologies on the kinematics of the ankle and to use it to compare the effect of different joint surface morphologies on the 3D kinematics of the ankle complex. Methodology. The study was conducted on ten cadaver ankle specimens. Image processing software (Analyze Direct. TM. ) was used to obtain 3D renderings of the articulating bones. The 3D bone models were then introduced into engineering design software packages (, Geomagic. TM. and Inventor. TM. ) to produce a set of four custom-fit virtual articular surfaces for each specimen: 1. Exact replica of the natural surfaces; 2. cylindrical; 3. truncated cone with apex oriented medially according to Inman's postulate; and 4. SSCL. The virtual TAR implants were exported to a 3D printing software and 3D physical models of each implant was produced in PLA using 3D printing (Figure 1). The intact cadaver was tested first in a specially design loading and measuring system [3] in which external moments were applied across the ankle in the three planes of motion and the resulting motion was measured through a surgical navigation system (Figure 1). Each of the four customized implant sets were then surgically introduced one at a time and the test was repeated. From the results, the ankle, subtalar and complex kinematics could be compared to that of the intact natural joint. Results and Conclusions. 1. Replacing the natural ankle joint surfaces by artificial exact replicas do not significantly affect the kinematic characteristics thus establishing good reliability of the experimental technique. This high reliability is an important finding proving that the combined factors involved in the process, such as replacing the natural surfaces with artificial replicas and the overall surgical procedure, do not significantly affect the kinematic characteristics of the ankle joint; 2. The SSCL implant produces close to intact joint kinematics (Figure 3), 3. The SSCL produces closer to normal kinematics then TARs with either cylindrical surfaces or those representing a symmetric truncated cone with apex oriented medially (Figure 3). For any figures or tables, please contact authors directly (see Info & Metrics tab above).

We present the case of a previously well 18 year old female who presented with an acute onset swollen painful right ankle with an overlying non-blanching purpuric rash. There were no associated systemic features. Ankle joint aspirate grew Neisseria Meningitides. She was treated with intravenous third generation cephalosporin's and surgical washout of the joint with improvement. Primary meningococcal arthritis (PMA) is rare and mostly associated with the knee joint. Presentation of meningococcal disease in this manner is easily missed or misdiagnosed as gonococcal disease or overlying cellulitis. Primary meningococcal arthritis is a rare form of septic arthritis. It can be misdiagnosed as an overlying cellulitis or as a gonococcal rash. Physicians should be aware of the possibility of this microorganism presenting as a septic arthritis, and understand the importance of joint aspiration at the centre of diagnosis

Introduction. In a previous study of subjects with no history of lower extremity injury or disease we found a linear relationship between body weight and peak hip, knee, and ankle joint forces during the stance phase of gait. To investigate the effect of total knee arthroplasty (TKA) on forces in the operated joints as well as the other joints of the lower extremities, we tested TKA subjects during gait and performed inverse dynamics analyses of the results. Materials and Methods. TKA subjects (3 M, 1 F; 58 ± 5 years; body mass index range (BMI): 26–36 kg/m. 2. ) participated in this investigation following institutional review board approval and informed consent. One subject had bilateral knee replacement. Each patient received the same implant design (4 PS, 1 CR). Data from previously tested control subjects (8 M, 4 F; 26 ± 4 years; BMI: 20–36 kg/m. 2. ) were used for comparison. Retro-reflective markers were placed over bony landmarks of each subject. A nine-camera video-based opto-electronic system was used for 3D motion capture as subjects walked barefoot at a self-selected speed on a 10 meter walkway instrumented with three force plates. Data were imported into a 12-body segment multibody dynamics model (AnyBody Technology) to calculate joint forces. Each leg contained 56 muscles whose mechanical effect was modeled by 159 simple muscle slips, each consisting of a contractile element. The models were scaled to match each subject's anthropometry and BMI. For the control subjects, only one limb was used in determining the relationship between body mass and peak joint force at the hip, knee, and ankle. For the TKA subjects, the peak joint forces were calculated for both the TKA limb and the contralateral limb. Results. Figure 1 shows the knee joint forces for the TKA subjects’ operated (red triangles) and contralateral knees (diamonds) along with the values for the control subjects (circles). Knee joint forces for the TKA subjects fell within or near the upper and lower 95% confidence intervals (dashed lines) of the mean regression lines (solid lines) for the control subjects. Three patients had other lower limb complications (osteoarthritis, ankle surgery). One subject favored the operated limb and another the non-operated limb, as ascertained from the corresponding hip (Figure 2) and ankle joint forces (Figure 3). Discussion. Modeling and simulation can be used to indirectly estimate joint forces in the implanted and non-operated joints. Our gait-lab derived inverse dynamics simulations suggest that joint forces following TKA fall within or near the normal range over a wide range of body weights and that the linear dependence between joint force and body weight applies to the implanted as well as non-implanted joints

Introduction

Temporary spanning fixation aims to provide bony stability whilst allowing access and resuscitation of traumatised soft-tissues. Conventional monolateral fixators are prone to half-pin morbidity in feet, variation in construct stability and limited weight-bearing potential. This study compares traditional delta-frame fixators to a circular trauma frame; a virtual tibial ring block spanned onto a fine-wire foot ring fixation.

Aim

The aim of this study was to compare the diagnostic accuracy of the Magnetic Resonance Imaging with that of Stress views of the ankle in testing the integrity of the lateral ankle ligaments. Arthroscopic diagnosis was used as the gold standard.

Introduction. Sheffield Children's Hospital specialises in limb lengthening for children. Soft tissue contracture and loss of range of motion at the knee and ankle are common complications. This review aims to look at therapeutic techniques used by the therapy team to manage these issues. Materials & Methods. A retrospective case review of therapy notes was performed of femoral and tibial lengthening's over the last 3 years. Included were children having long bone lengthening with an iIntramedullary nail, circular frame or mono-lateral rail. Patients excluded were any external fixators crossing the knee/ankle joints. Results. 20 tibial and 25 femoral lengthening's met the inclusion criteria. Pathologies included, complex fractures, limb deficiency, post septic necrosis and other congenital conditions leading to growth disturbance. All patients had issues with loss of motion at some point during the lengthening process. The knee and foot/ankle were equally affected. Numerous risk factors were identified across the cohort. Treatment provided included splinting, serial casting, bolt on shoes, exercise therapy, electrical muscle stimulation and passive stretching. Conclusions. Loss of motion in lower limb joints was common. Patients at higher risk were those with abnormal anatomy, larger target lengthening's, poor compliance or lack of access to local services. Therapy played a significant role in managing joint motion during treatment. However, limitations were noted. No one treatment option gave preferential outcomes, selection of treatment needed to be patient specific. Future research should look at guidelines to aid timely input and avoid secondary complications

Medial knee OA effects approximately 4.1 million people in England. Non-surgical strategies to lower knee joint loading is commonly researched in the knee OA literature as a method to alleviate pain and discomfort. Medial knee OA is much more prevalent than lateral knee OA due to the weight bearing line passing medial to the knee causing an external knee adduction moment (KAM). Numerous potential gait retraining strategies have been proposed to reduce either the first and/or the second peak KAM, including: toe-in gait, toe-out gait, lateral trunk lean and medial thrust gait. Gait retraining has been researched with little regard to the biomechanical consequences at the hip and ankle joints. This systematic review aimed to establish whether gait retraining can reduce medial knee loading as assessed by first and second peak KAMs, establish what are the biomechanical effects a reduced KAM has on other lower limb joint biomechanics and outline patient/participant reported outcomes on how easy the gait retraining style was to implement. The protocol for this systematic review was registered with PROSPERO on the 23rd January 2018 (registration ID: CRD42018085738). 13 databases were searched by one author (J.B.B). Additionally, PROSPERO was searched for ongoing or recently completed systematic reviews. Risk of bias was assessed using the Downs and Black quality index. Search: Group one consisted of keywords “walk” OR “gait”. Keywords “knee” OR “adduction moment” built up the second group. Group three consisted “osteoarthriti” OR “arthriti” OR “osteo arthriti”, OR “OA”. Group four included “hip” OR “ankle”. the searched results of each group were combined with conjunction “AND” in all fields. Out of the eight different gait retraining strategies identified, trunk lean reduced first peak KAM the most, which was evaluated in 3 studies, reducing first peak KAM by 20%-65%. There was a lack of collective pelvic, hip and/or ankle joint biomechanical variables reported across all 11 studies. Of eight gait retraining styles identified, the strategy that reduced first peak KAM the most was an increased lateral trunk lean, which was evaluated in 3 different studies. This is the first systematic review that has highlighted that there is limited evidence of the biomechanical consequences of a reduced knee joint load has on the pelvic, hip and/or ankle joints when undertaking gait retraining protocols. Future studies assessing gait retraining strategies should provide biomechanical outputs for other lower limb joints other than the knee joint, as well as providing participant perceptions on the level of difficulty the gait style is to perform

Introduction. Bone transport and distraction osteogenesis have been shown to be an effective treatment for significant bone loss in the tibia. However, traditional methods of transport are often associated with high patient morbidity due to the pain and scarring caused by the external frame components transporting the bone segment. Prolonged time in frame is also common as large sections of regenerate need significant time to consolidate before the external fixator can be removed. Cable transport has had a resurgence with the description of the balanced cable transport system. However, this introduced increasingly complex surgery along with the risk of cable weave fracture. This method also requires frame removal and intramedullary nailing, with a modified nail, to be performed in a single sitting, which raised concern regarding potential deep infection. An alternative to this method is our modified cable transport system with early intramedullary nail fixation. Internal cables reduce pain and scarring of the skin during transport and allow for well controlled transport segment alignment. The cable system is facilitated through an endosteal plate that reduces complications and removes the need for a single-stage frame removal and nailing procedure. Instead, the patients can undergo a pin-site holiday before nailing is performed using a standard tibial nail. Early intramedullary nailing once transport is complete reduces overall time in frame and allows full weight bearing as the regenerate consolidates. We present our case series of patients treated with this modified cable transport technique. Methodolgy. Patients were identified through our limb reconstruction database and clinic notes, operative records and radiographs were reviewed. Since 2019, 8 patients (5 male : 3 female) have undergone bone transport via our modified balanced cable transport technique. Average age at time of transport was 39.6 years (range 21–58 years) with all surgeries performed by the senior author. Patients were followed up until radiological union. We recorded the length of bone transport achieved as well as any problems, obstacles or complications encountered during treatment. We evaluated outcomes of full weight bearing and return to function as well as radiological union. Results. 4/8 bone defects were due to severely comminuted open fractures requiring extensive debridement. All other cases had previously undergone fixation of tibial fractures which had failed due to infection, soft tissue defects or mal-reduction. The mean tibial defect treated with bone transport was 41mm (range 37–78mm). From the start of cable transport to removal of external fixator our patients spent an average of 201 days in frame. 7/8 patients underwent a 2-week pin-site holiday and subsequent insertion of intramedullary nail 2 weeks later. One patient had sufficient bony union to not require further internal fixation after frame removal. 10 problems were identified during treatment. These included 4 superficial infections treated with antibiotics alone and 5 issues with hardware, which could be resolved in the outpatient clinic. 1 patient had their rate of transport slowed due to poor skin quality over the site of the regenerate. 4 obstacles resulted in a return to theatre for additional procedures. 1 patient had a re-do corticotomy and 3 had revision of their internal cable transport constructs due to decoupling or screw pull out. 1 patient had residual ankle joint equinus following treatment which required an Achilles tendon lengthening procedure. Another patient underwent treatment for DVT. There were no deep infections identified and no significant limb length discrepancies or deformities. Conclusions. Overall, we have found that our modified balanced cable transport technique has allowed for successful bone transport for significant defects of the tibia. We have learned from the obstacles encountered during this case series to avoid unnecessary return trips to theatre for our future transport patients. The internal cable system allowed all patients to complete their planned transport without excessive pin tract scarring or pain. Early conversion to intramedullary nail allowed for a shorter time in frame with continued full weight bearing as the regenerate consolidated. No metalwork failure or deformity has occurred in relation to docking site union. All patients have made a good return to pre-operative function during their follow-up period with no evidence of late complications such as deep infection

Aim. Post traumatic distal tibia osteomyelitis (DTOM) with an upper ankle joint involvement is a serious complication after primary osteosynthesis and can be a nightmare for the patient and the surgeon as well. Our aim was to identify mayor complications during treatment and to find the way to prevent or treat them. Method. It is a retrospective analysis of eight patients with DTOM and an upper ankle joint involvement treated in our institution from 2012 to 2018. The average size of a bone defect after a debridement was 9 centimeters (4–15). Patients were treated in two stages. First stage was segmental bone resection, external fixation and soft tissue envelope reconstruction if necessary. At second stage a distraction frame was applied and proximal corticotomy performed. In all but one case a circular frame was used. Results. We have had one major intra-operative complication, an injury of arteria tibialis posterior during the corticotomy procedure. Except in one patient we did not observe major problems with pin-track infections. Despite bone-grafting in all patients, we observed three nonunions of docking site. We treated them by external fixator in two and retrograde intramedullar nail in one case. In two patient the distraction callus was weak. We had to bone graft and secure the callus with a plate in one and use a retrograde reamed intramedullar nail in second patient. We have observed two callus fracture after removal of the frame. A surgery was needed for both because of the deformation. The first patient was treated by new external frame, the second by retrograde reamed intramedullar nail. Conclusions. Callus distraction is a valuable option to treat a bone defect. The procedure has many possible problems and complications, especially during treatment of defects larger than six centimeters. It is very difficult for patients to tolerate a frame more than one year. We have found the use of an intramedullar tibial nail inserted in a retrograde way as a helpful option not just to shorten the time of external frame, but in combination with reaming also to accelerate the healing of the distraction callus and the upper ankle joint arthrodesis as well

Many pre-clinical models of atrophic non-union do not reflect the clinical scenario, some create a critical size defect, or involve cauterization of the tissue which is uncommonly seen in patients. Atrophic non-union is usually developed following high energy trauma leading to periosteal stripping. The most recent reliable model with these aspects involves creating a non-critical gap of 1mm with periosteal and endosteal stripping. However, this method uses an external fixator for fracture fixation, whereas intramedullary nailing is the standard fixation device for long bone fractures. OBJECTIVES. To establish a clinically relevant model of atrophic non-union using intramedullary nail and (1) ex vivo and in vivo validation and characterization of this model, (2) establishing a standardized method for leg positioning for a reliable x-ray imaging. Ex vivo evaluation: 40 rat's cadavers (adult male 5–6 months old), were divided into five groups (n=8 in each): the first group was fixed with 20G intramedullary nail, the second group with 18G nail, the third group with 4-hole plate, the fourth group with 6-hole plate, and the fifth group with an external fixator. Tibiae were harvested by leg disarticulation from the knee and ankle joints. Each group was then subdivided into two subgroups for mechanical testing: one for axial loading (n=4) and one for 4-point bending (n=4) using Zwick/Roell® machine. Statistical analysis was carried out by ANOVA with a fisher post-hoc comparison between groups. A p-value less than 0.05 was considered statistically significant. To maintain the non-critical gap, a spacer was inserted in the gap, the design was refined to minimize the effect on the healing surface area. In vivo evaluation was done to validate and characterize the model. Here, a 1 mm gap was created with periosteal and endosteal stripping to induce non-union. The fracture was then fixed by a hypodermic needle. A proper x-ray technique must show fibula in both views. Therefore, a leg holder was used to hold the knee and ankle joints in 90º flexion and the foot was placed in a perpendicular direction with the x-ray film. Lateral view was taken with the foot parallel to the x-ray film. Ex vivo: axial load stiffness data revealed that intramedullary nails are significantly stronger and stiffer than other devices. Bending load to failure showed that 18G nails are significantly stronger than 20G, thus it is used for the in vivo experiments. In vivo: final iteration revealed 3/3 non-union, and in controls with the periosteum and endosteum intact but with the 1mm non-critical gap, it progressed to 3/3 union. X-ray positioning: A-P view in supine position, there was an unavoidable degree of external rotation in the lower limb, thus the lower part of the fibula appeared behind the tibia. To overcome this, a P-A view of the leg was performed with the body in prone rather, this arrangement allowed both upper and lower parts of the fibula to appear clearly in both views. We report a novel model of atrophic non-union, the surgical procedure is relatively simple and the model is reproducible

This study aimed to examine the effect of high tibial osteotomy (HTO) on the ankle and subtalar joints via analysis of static radiographic alignment. We hypothesised that surgical alteration of the alignment of the proximal tibia would result in compensatory distal changes. 35 patients recruited as part of the wider Biomechanics and Bioengineering Centre Versus Arthritis HTO study between 2011 and 2018 had pre- and postoperative full-length weightbearing radiographs taken of their lower limbs. In addition to standard alignment measures of the limb and knee (mechanical tibiofemoral angle, Mikulicz point, medial proximal tibial angle), additional measures were taken of the ankle/subtalar joints (lateral distal tibial angle, ground-talus angle, joint line convergence angle of the ankle) as well as a novel measure of stance width. Results were compared using a paired T-test and Pearson's correlation coefficient. Following HTO, there was a significant (5.4°) change in subtalar alignment. Ground-talus angle appeared related both to the level of malalignment preoperatively and the magnitude of the alignment change caused by the HTO surgery; suggesting subtalar positioning as a key adaptive mechanism. In addition to compensatory changes within the subtalar joints, the patients on average had a 31% wider stance following HTO. These two mechanisms do not appear to be correlated but the morphology of the tibial plafond may influence which compensatory mechanisms are employed by different subgroups of HTO patients. These findings are of vital importance in clinical practice both to anticipate potential changes to the ankle and subtalar joints following HTO but it could also open up wider indications for HTO in the treatment of ankle malalignment and osteoarthritis

Background. Occasionally, patients experience new or increased ankle pain following total knee arthroplasty (TKA). The aims of this study were to determine (1) how the correction of varus malalignment of the lower limb following TKA affected changes in alignment of the ankle and hindfoot, (2) the difference in changes in alignment of the ankle and hindfoot between patients with and without ankle osteoarthritis (OA), and (3) whether the rate of ankle pain and the clinical outcome following TKA differed between the 2 groups. Methods. We retrospectively reviewed prospectively collected data of 56 patients (99 knees) treated with TKA. Among these cases, concomitant ankle OA was found in 24 ankles. Radiographic parameters of lower-limb, ankle, and hindfoot alignment were measured preoperatively and 2 years postoperatively. In addition, ankle pain and clinical outcome 2 years after TKA were compared between patients with and without ankle OA. Results. The orientation of the ankle joint line relative to the ground improved from varus 9.4° to varus 3.4°, and the valgus compensation of the hindfoot for the varus tilt of the ankle joint showed a 2.2° decrease following TKA. Patients in the group with ankle OA showed decreased flexibility of the hindfoot resulting in less preoperative valgus compensation (p = 0.022) compared with the group without ankle OA. The postoperative hindfoot alignment was similar between the 2 groups because of the smaller amount of change in patients with ankle OA. The group with ankle OA had a higher rate of increased ankle pain (38% compared with 16%) as well as a worse Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (mean of 22.2 compared with 14.2) following TKA. Conclusions. A considerable proportion of patients who underwent TKA had concomitant ankle OA with reduced flexibility of the hindfoot. These patients experienced increased ankle pain following TKA and a worse clinical outcome

Power production in the terminal stance phase is essential for propelling the body forward during walking and is generated primarily by ankle plantarflexion. Osteoarthritis (OA) of the ankle restricts joint range of motion and is expected to reduce power production at that ankle. This loss of power may be compensated for by unaffected joints on both the ipsilateral and contralateral limbs resulting in overloading of the asymptomatic joints. Total ankle arthroplasty (TAA) has been shown to reduce pain and has the potential to restore range of motion and therefore increase ankle joint power, which could reduce overloading of the unaffected joints and increase walking speed. The purpose of this study was to test the hypothesis that ankle OA causes a loss of power in the affected ankle, compensatory power changes in unaffected lower limb joints, and that TAA will increase ankle power in the repaired ankle and reduce compensatory changes in other joints. One hundred and eighty-three patients (86 men, 97 women with average ages 64.1 and 62.4 years respectively) requiring surgical intervention for ankle OA were prospectively enrolled. Implant selection of either a fixed (INBONE or Salto Talaris) or mobile (STAR) bearing implant was based on surgeon preference. Three-dimensional kinematics and kinetics were collected prior to surgery and one year post-operatively during self-selected speed level walking using an eight-camera motion capture system and a series of force platforms. Subject walking speed and lower extremity joint power during the last third of stance at the ankle, knee, and hip were calculated bilaterally and compared before and after surgical intervention across the entire group and by implant type (fixed vs. mobile), and gender using a series of ANOVAs (JMP SAS, Cary, NC), with statistical significance defined as p < 0 .05. There were no gender differences in age, walking speed, or joint power. All patients increased walking as a result of surgery (0.87 m/s±0.26 prior to surgery and 1.13 m/s±0.24 after surgery, p < 0 .001) and increased total limb power. Normalized to total power (which accounts for changes in speed and distribution of power production across joints), prior to surgery the affected ankle contributed 19%±10% of total power while the unaffected ankle contributed 42%±12% (P < 0 .001). After surgery, the affected ankle increased to 25%±9% of total power and the unaffected ankle decreased to 38%±9% of total (P < 0.001). Other joints showed no significant power changes following surgery. Fixed bearing implants provide greater surgical ankle power improvement (61% versus 29% increase, p < 0 .002). Much of that change was due to the fact that those that received fixed-bearing implants had significantly lower walking speed and power before surgery. Ankle OA reduced ankle power production, which was partially compensated for by the unaffected ankle. TAA increases walking speed and power at the affected ankle while lowering power production on the unaffected side. The modifications in power production could lead to increased physical activity and reduced overloading of asymptomatic joints

Nearly one quarter of ankle fractures have a recognized syndesmosis injury. An intact syndesmosis ligament complex stabilizes the distal tibio-fibular joint while allowing small, physiologic amounts of relative motion. When injured, malreduction of the syndesmosis has been found to be the most important independent factor that contributes to inferior functional outcomes. Despite this, significant variability in surgical treatment remains. This may be due to a poor understanding of normal dynamic syndesmosis motion and the resultant impact of static and dynamic fixation on post-injury syndesmosis kinematics. As the syndesmosis is a dynamic structure, conventional CT static images do not provide a complete picture of syndesmosis position, giving potentially misleading results. Dynamic CT technology has the ability to image joints in real time, as they are moved through a range-of-motion (ROM). The aim of this study was to determine if syndesmosis position changes significantly throughout ankle range of motion, thus warranting further investigation with dynamic CT. This is an a priori planned subgroup analysis of a larger multicentre randomized clinical trial, in which patients with AO-OTA 44-C injuries were randomized to either Tightrope or screw fixation. Bilateral ankle CT scans were performed at 1 year post-injury, while patients moved from maximal dorsiflexion (DF) to maximal plantar flexion (PF). In the uninjured ankles, three measurements were taken at one cm proximal to the ankle joint line in maximal DF and maximal PF: Anterior (ASD), middle (MSD), and posterior (PSD) syndesmosis distance, in order to determine normal syndesmosis position. Paired samples t-tests compared measurements taken at maximal DF and maximal PF. Twelve patients (eight male, six female) were included, with a mean age of 44 years (±13years). The mean maximal DF achieved was 1-degree (± 7-degrees), whereas the mean maximal PF was 47-degrees (± 8-degrees). The ASD in DF was 3.0mm (± 1.1mm) versus 1.9mm (± 0.8mm) in PF (p<0.01). The MSD in DF was 3.3mm (±1.1mm) versus 2.3mm (±0.9mm) in PF (p<0.01). The PSD in DF was 5.3mm (±1.5mm) versus 4.6mm (±1.9mm) in PF (p<0.01). These values are consistent with the range of normal parameters previously reported in the literature, however this is the first study to report the ankle position at which these measurements are acquired and that there is a significant change in syndesmosis measurements based on ankle position. Normal syndesmosis position changes in uninjured ankles significantly throughout range of motion. This motion may contribute to the variation in normal anatomy previously reported and controversies surrounding quantifying anatomic reduction after injury, as the ankle position is not routinely standardized, but rather static measurements are taken at patient-selected ankle positions. Dynamic CT is a promising modality to quantify normal ankle kinematics, in order to better understand normal syndesmosis motion. This information will help optimize assessment of reduction methods and potentially improve patient outcomes. Future directions include side-to-side comparison using dynamic CT analysis in healthy volunteers

In some regions in Asia or Arab, there are lifestyles without chair or bed and sitting down on a floor directly, by flexing their knee deeply. However, there are little data about the joint angles, muscle forces or joint loads at such sitting postures or descending to and rising from the posture. In this study, we report the knee joint force and the muscle forces of lower limb at deep squatting and kneeling postures. The model to estimate the forces were constructed as 2D on sagittal plane. Floor reacting force, gravity forces and thigh-calf contact force were considered as external forces. And as the muscle, rectus and vastus femoris, hamstrings, gluteus maximus, gastrocnemius and soleus were taken into the model. The rectus and vastus were connected to the tibia with patella and patella tendon. First the muscle forces were calculated by the moment equilibrium conditions around hip, knee and ankle joint, and then the knee joint force was calculated by the force equilibrium conditions at tibia and patella. For measuring the acting point of the floor reacting force, thigh-calf contact force and joint angles during the objective posture, we performed the experiments. The postures to be subjected were heel-contact squatting (HCS), heel-rise squatting (HRS), kneeling and seiza (Japanese sedentary kneeling), as shown in the Fig.1. The test subjects were ten healthy male, and the average height was 1.71[m], weight was 66.1[kgf] and age was 21.5[years]. The thigh-calf contact force and its acting point were measured by settling the pressure distribution sensor sheet between thigh and calf. Results were normalized by body weight, and shown in Fig.1. The thigh-calf contact force was the largest at the heel-rise squatting posture (1.16BW), and the smallest at heel-contact squatting (0.60BW). The patellofemoral and the tibiofemoral joint forces were shown in the figure. Both forces were the largest at the heel-contact squatting, and were the smallest at the seiza posture. And it might be estimated that the thigh-calf contact force acted anterior when the ankle joint dorsiflexed, and the force was larger when the hip joint extended. The thigh-calf contact force might be decided by not only the knee joint angle but also the hip and ankle joints. As a limitation of this study, we should mention about the effect of the neglected soft tissues. It could be considerable that the compressive internal force of the soft tissues behind a knee joint substance the tibiofemoral force, and then the real tibiofemoral force might be smaller than the calculated values in this study. Then, the tensile force of quadriceps also might be smaller, and then the patellofemoral joint force is also small

Tunning fork lines (TFL) were drawn on ankle anterior-posterior radiograph to assess the talar shift. A 3-D ankle joint reconstruction was prepared by mapping normal ankle joint using auto CAD in 1997. Tunning fork lines were drawn using normal anatomical landmarks on saggital, coronal and transverse planes. The ankle joint anatomical relationship with talus was studied in various rotation simulating radiographic anterior-posterior views and talar shift was studied. Between 2006 and 2012 on antero-posterior view of ankle radiographs and PACS, ‘Tunning Fork Lines’ (TFL) were drawn. The superior two vertical lines of the TFL were drawn above the ankle joint perpendicular to the distal tibial articular surface. First line tangent to anterior lip of the inferior tibio-fibular joint and second line tangent to the posterior lip of the inferior tibio-fibular joint parallel to each other. The horizontal third line was drawn parallel to distal tibial articular surface perpendicular to first two lines connecting them. The fourth line (handle of the tunning fork) was drawn vertically below the ankle joint midway between the first two lines perpendicular to the third line. In a normal radiograph the superior-lateral dome of the talus lies medial to the handle of TFL, and in ankle with talar shift the dome of the talus crosses this line laterally. In two district hospitals 100 radiographs were observed by 4 observers in 67 males and 33 females with mean age of 49 (15–82) years. The TFL confirmed talar shift with sensitivity of 99.2 % showing talarshift and inferior tibio-fibular ankle diastasis. We conclude that in ankle anterio-posterior view it is possible to comment on the talar shift and diastasis of the ankle joint if proper ankle mortise view is not available

Tunning fork lines (TFL) were drawn on ankle anterior-posterior radiographs to assess the talar shift in ankle fractures. A 3-D ankle joint reconstruction was prepared by mapping normal ankle joint using auto CAD in 1997. TFL were drawn using normal anatomical landmarks on saggital, coronal and transverse planes. The ankle joint anatomical relationship with talus was studied in various rotation simulating radiographic anterior-posterior views and talar shift was studied. Between 2006 and 2012 on antero-posterior view of ankle radiographs and PACS, TFL were drawn. The premise is that in a normal radiograph the superior-lateral dome of the talus lies medial to the handle of TFL, and in ankle with talar shift the dome of the talus would cross this line laterally. In two district hospitals 100 radiographs were observed by 4 observers in 67 males and 33 females with mean age of 49 (15–82) years. The TFL confirmed talar shift with sensitivity of 99.2 % showing talarshift and inferior tibio-fibular ankle diastasis. We conclude that in ankle anterio-posterior view it is possible to comment on the talar shift and diastasis of the ankle joint, even if proper ankle mortise views were not available

The alignment of the knee following total knee arthroplasty (TKA), especially tibial alignment, is a major factor determining the long-term survival of the prosthesis. A disadvantage of using extramedullary alignment guides of the tibia for TKA is the difficulty in correctly identifying the ankle center, and surgeons cannot construct the tibial mechanical axis correctly without the correct location of the ankle center. Although numerous studies have reported bony and soft tissue landmarks for determining the ankle center, a consensus has yet to be reached regarding this matter. This problem is complicated by rotational mismatch between the knee and ankle joint. Because it is difficult to frontalize the knee and ankle joints simultaneously on the same frontal plane. When using extramedullary alignment guides of the tibia, the guides should be applied to the tibia while keeping the knees frontal. The purpose of this study was to determine the position of the ankle center, which is useful for setting extramedullary alignment guides, by using CT data of osteoarthritic knees. CT data of fifty patients (fifty knees) with varus osteoarthritic knees for primary TKA were retrospectively analyzed. Tibial anteroposterior (AP) axis and transmalleolar axis (TMA) were used as reference axes of the knee and ankle joint, respectively. When using above these reference axes, the offset distance from the bimalleolar center was measured as the position of the ankle center. The angular errors were defined as the varus angle of the proximal tibial cut caused by this offset distance when the position of the ankle center was regarded as the bimalleolar center. The position of the ankle center was 1.5 ± 1.2 mm and 2.3 ± 1.5 mm medial to the bimalleolar center with reference to tibial AP axis and TMA, respectively. There was a significant difference between the position of the ankle center with respect to the tibial AP axis and with respect to the TMA (p < 0.01). The mean angular error with respect to the tibial AP axis was 0.3 ± 0.2 °, and the value with respect to TMA was 0.4 ± 0.2 °. The maximum varus angular error along tibial AP axis was less than 0.7 degrees. The positions of the ankle center differed according to the reference axis. Since the angular error was small enough, the bimalleolar center along the tibial AP axis could be used as the ankle center in TKA patients with osteoarthritis knees

In the vast majority of patients, the anatomical and mechanical axes of the tibia in the coronal plane are widely accepted to be equivalent. This philosophy guides the design and placement of orthopaedic implants within the tibia and in both the knee and ankle joints. However, the presence of coronal tibial bowing may result in a difference between these two axes and hence cause suboptimal placement of implanted prostheses. Although the prevalence of tibial bowing in adults has been reported in Asian populations, to date no exploration of this phenomenon in a Western population has been conducted. The aim of this study was to quantify the prevalence of coronal tibial bowing in a Western population. This was an observational retrospective cohort study using anteroposterior long leg radiographs collected prior to total knee arthroplasty in our high volume arthroplasty unit. Radiographs were reviewed using a Picture Archiving and Communication System. Using a technique previously described in the literature for assessment of tibial bowing, two lines were drawn, each one third of the length of the tibia. The first line was drawn between the tibial spines and the centre of the proximal third of the tibial medullary canal. The second was drawn from the midpoint of the talar dome to the centre of the distal third of the tibial medullary canal. The angle subtended by these two lines was used to determine the presence of bowing. Bowing was deemed significant if more than two degrees. The position of the apex of the bow determined whether it was medial or lateral. Measurements were conducted by a single observer and 10% of measurements were repeated by the same observer and also by two separate observers to allow calculation of intraclass correlation coefficients (ICCs). A total of 975 radiographs consecutively performed in the calendar years 2015–16 were reviewed, 485 of the left leg and 490 of the right. In total 399 (40.9%) tibiae were deemed to have bowing more than two degrees. 232 (23.8%) tibiae were bowed medially and 167 (17.1%) were bowed laterally. The mean bowing angle was 3.51° (s.d. 1.24°) medially and 3.52° (s.d. 1.33°) laterally. Twenty-three patients in each group (9.9% medial/13.7% lateral) were bowed more than five degrees. The distribution of bowing angles followed a normal distribution, with the maximal angle observed 10.45° medially and 9.74° laterally. An intraobserver ICC of 0.97 and a mean interobserver ICC of 0.77 were calculated, indicating excellent reliability. This is the first study reporting the prevalence of tibial bowing in a Western population. In a significant proportion of our sample, there was divergence between the anatomical and mechanical axes of the tibia. This finding has implications for both the design and implantation of orthopaedic prostheses, particularly in total knee arthroplasty. Further research is necessary to investigate whether prosthetic implantation based on the mechanical axis in bowed tibias results in suboptimal implant placement and adverse clinical outcomes