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

Aims . To assess the effect of high tibial and distal femoral osteotomies (HTO and DFO) on the pressure characteristics of the ankle joint. Materials and Methods. Varus and valgus malalignment of the knee was simulated in human cadaver full-length legs. Testing included four measurements: baseline malalignment, 5° and 10° re-aligning osteotomy, and control baseline malalignment. For HTO, testing was rerun with the subtalar joint fixed. In order to represent half body weight, a 300 N force was applied onto the femoral head. Intra-articular sensors captured ankle pressure. Results. In the absence of restriction of subtalar movement, insignificant migration of the centre of force and changes of maximal pressure were seen at the ankle joint. With restricted subtalar motion, more significant lateralisation of the centre of force were seen with the subtalar joint in varus than in valgus position. Changes in maximum pressure were again not significant. . Conclusion. The re-alignment of coronal plane knee deformities by HTO and DFO altered ankle pressure characteristics. When the subtalar joint was fixed in the varus position, migration of centre of force after HTO was more significant than when the subtalar joint was fixed in valgus. Cite this article: Bone Joint J 2017;99-B:59–65

A cavovarus foot deformity was simulated in cadaver specimens by inserting metallic wedges of 15° and 30° dorsally into the first tarsometatarsal joint. Sensors in the ankle joint recorded static tibiotalar pressure distribution at physiological load. The peak pressure increased significantly from neutral alignment to the 30° cavus deformity, and the centre of force migrated medially. The anterior migration of the centre of force was significant for both the 15° (repeated measures analysis of variance (ANOVA), p = 0.021) and the 30° (repeated measures ANOVA, p = 0.007) cavus deformity. Differences in ligament laxity did not influence the peak pressure. These findings support the hypothesis that the cavovarus foot deformity causes an increase in anteromedial ankle joint pressure leading to anteromedial arthrosis in the long term, even in the absence of lateral hindfoot instability

Aims: To identify the distraction forces and contact pressures of the ankle joint at two different joint positions during articulated ankle distraction. Material and Methods: Four amputated lower limbs were collected from patients undergoing amputation for vascular disease and frozen at -70° C. The ankle joint of the specimens were normal. Before use the limbs were thawed at room temperature for 24 hours. The skin and subcutaneous tissues were removed. A Sheffield ring fixator consisting of a proximal tibial ring and a foot plate connected through three threaded bars and hinges aligned with ankle axis was mounted on the limb. Force transducers were placed in the threaded bars between the tibial ring and the foot plate on the lateral, medial and posterior aspect of the ankle joint to measure the ankle distraction forces. Once the ankle distraction forces have been measured an anterior ankle arthrotomy was performed to permit the insertion of Fuji pressure sensitive film within the ankle joint. The limb-fixator construct was mounted in a loading machine and axially loaded on the tibia. The ankle joint was distracted at 2 mm intervals to a maximum of 20 mm. Pressure sensitive film was introduced in the ankle joint at each distraction interval and the tibia was axially loaded at 350, 700, 1050 and 1400N (half to two times body weight). Results: The forces necessary to distract the ankle joint are almost double in the medial side than the lateral side. With 10° of plantarflexion the forces necessary to distract the lateral side increase by about 10%. We found the center of pressure of the ankle joint to be situated in the antero-medial quadrant, close to the center of the ankle joint. Distraction of the ankle joint by 5 mm eliminated any contact pressures at the ankle joint when the tibia was loaded up to 700N (one time body weight). When the joint was distracted by 10 mm no contact pressures were found in the ankle when loaded up to 1400N (two times body weight). Conclusions: With the ankle in the plantigrade position the forces necessary to distract the ankle joint are double in the medial side when compared to the lateral side. Plantarflexion increases the forces necessary to distract the lateral aspect of the ankle. This finding may have clinical implications when distracting ankle joints with equinus deformities as this can increase the risk of damaging the lateral ankle ligaments leading to ankle instability. In our opinion equinus deformities should be corrected before the start of ankle joint distraction. The center of pressure of the ankle joint is situated in the antero-medial quadrant. Distraction of 5 mm will eliminate ankle contact pressure up to one times body weight whereas distraction of 10 mm will eliminate contact pressures up to two times body weight

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

Our work is based on the analysis of 104 patients with suppurative posttraumatic osteoarthritis of the ankle joint. By prolonged septic arthritis with degradation of articular surfaces of ankle and shin bones we used necrectomia with osteoarthrotomy and compression arthrodesis in the mechanism of external fixation, which allows to radically sanify the nidus of infection and eliminate the inflammatory process all together. This operation was performed for 68 patients. Surgical treatment for 18 patients with septic arthritis of the ankle joint with considerable involvement of ankle joint metaepiphysis was performed in the following way. We performed segmental resection of the shin bone distal part, put in external fixation mechanism with the possibility of defect building, and then we performed the osteotomy of the shin bone in its upper one-third. On the 10th day we started performing building of defect by Ilizarov. For six patients with ankle joint septic arthritis with considerable involvement of ankle bone we performed its subtotal resection and compression arthrodesis in the external fixation mechanism. For patients with total overall affection of the ankle bone we performed ankle bone excision and tibialcalcaneal fusion. For three patients we performed ankle bone excision with tibialcalcaneal fusion and external fixation. For nine patients where it was not possible to perform a single-stage fusion of shin and heel bones we used external fixation mechanism with the possibility to move the shin bone fragment. Then we performed open fusion of shin and heel bones. The result was considered to be position (92% of patients) in case of extremity support ability recovery, suppurative process elimination and bony ankylosis achievement. Original ankle joint injury nature and localization are very important in selecting the necessary surgical treatment variant. Differential surgical treatment tactics selection for patients with suppurative ankle joint osteoarthritis together with adequate usage of conservative therapy allow to eliminate active purulo-necrotic process and restore the extremity support function for most patients

Aims. Accurate identification of the ankle joint centre is critical for estimating tibial coronal alignment in total knee arthroplasty (TKA). The purpose of the current study was to leverage artificial intelligence (AI) to determine the accuracy and effect of using different radiological anatomical landmarks to quantify mechanical alignment in relation to a traditionally defined radiological ankle centre. Methods. Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A sub-cohort of 250 radiographs were annotated for landmarks relevant to knee alignment and used to train a deep learning (U-Net) workflow for angle calculation on the entire database. The radiological ankle centre was defined as the midpoint of the superior talus edge/tibial plafond. Knee alignment (hip-knee-ankle angle) was compared against 1) midpoint of the most prominent malleoli points, 2) midpoint of the soft-tissue overlying malleoli, and 3) midpoint of the soft-tissue sulcus above the malleoli. Results. A total of 932 bilateral full-limb radiographs (1,864 knees) were measured at a rate of 20.63 seconds/image. The knee alignment using the radiological ankle centre was accurate against ground truth radiologist measurements (inter-class correlation coefficient (ICC) = 0.99 (0.98 to 0.99)). Compared to the radiological ankle centre, the mean midpoint of the malleoli was 2.3 mm (SD 1.3) lateral and 5.2 mm (SD 2.4) distal, shifting alignment by 0.34. o. (SD 2.4. o. ) valgus, whereas the midpoint of the soft-tissue sulcus was 4.69 mm (SD 3.55) lateral and 32.4 mm (SD 12.4) proximal, shifting alignment by 0.65. o. (SD 0.55. o. ) valgus. On the intermalleolar line, measuring a point at 46% (SD 2%) of the intermalleolar width from the medial malleoli (2.38 mm medial adjustment from midpoint) resulted in knee alignment identical to using the radiological ankle centre. Conclusion. The current study leveraged AI to create a consistent and objective model that can estimate patient-specific adjustments necessary for optimal landmark usage in extramedullary and computer-guided navigation for tibial coronal alignment to match radiological planning. Cite this article: Bone Jt Open 2022;3(10):767–776

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).

Endoprosthetic replacement of the distal tibia and ankle joint for a primary bone tumour is a rarely attempted and technically challenging procedure. We report the outcome of six patients treated between 1981 and 2007. There were four males and two females, with a mean age of 43.5 years (15 to 75), and a mean follow-up of 9.6 years (1 to 27). No patient developed a local recurrence or metastasis. Two of the six went on to have a below-knee amputation for persistent infection after a mean 16 months (1 to 31). The four patients who retained their endoprosthesis had a mean musculoskeletal tumour society score of 70% and a mean Toronto extremity salvage score of 71%. All were pain free and able to perform most activities of daily living in comfort. A custom-made endoprosthetic replacement of the distal tibia and ankle joint is a viable treatment option for carefully selected patients with a primary bone tumour. Patients should, however, be informed of the risk of infection and the potential need for amputation if this cannot be controlled

The posterolateral approach to ankle joint is well suited for ORIF of posterior malleolar fractures. There are no major neurovascular structures endangering this approach other than the sural nerve. The sural nerve is often used as an autologous peripheral nerve graft and provides sensation to the lateral aspect of the foot. Hence every attempt must be made to protect the sural nerve. The aim of this paper is to measure the precise distance of the sural nerve from surrounding soft tissue structures. This is a retrospective image review study including patients with MRI of their ankle from January 09 - Nov 2010. We indentified 78 MRI scans out of which 64 were deemed eligible for assessment. All measurements were made from Axial T1 slices. Measurements were made from the lateral aspect of the TA to the central of the sural nerve, central of sural nerve to the posterior aspect of the peronei muscles and central of the sural nerve to the posterior aspect of fibula. Data were collected on a Microsoft Excel spreadsheet and the descriptive statistics calculated. The key findings of the paper is the safety window for the sural nerve from the lateral border of TA is 7mm, 1.3cm and 2cm at 3 cm above ankle joint, at the ankle joint and at the distal tip of fibula respectively. Similarly the safety window for the nerve from the posterior aspect of fibula is 2cm, 1.6cm, 1.6cm at 3cm above ankle, at the ankle joint and the distal tip of fibula respectively. Our study demonstrates the close relationship of the nerve in relation to tendoachilles, peronei and fibula in terms of exact measurements. The safety margins established in this study should enable the surgeon in preventing endangerment of the sural nerve encountered in this approach

The technique of the transfibular approach for arthrodesis of the ankle joint is described. The results of this operation in a series of thirty cases shows that the procedure is reliable if the technique is carried out faithfully. The two cases in which a first operation failed can both be explained by errors of technique or after-treatment

Purpose of the study: Stiffness of the ankle joint is a common complication after fracture, surgical repair, or total ankle arthroplasty. Dorsiflexion is generally the most limited movement. A few older papers have focused on this common problem in orthopaedic surgery of the ankle joint but have been controversial. The purpose of this anatomy study was to evaluate the efficacy and quantify the impact of releasing the collateral ligaments of the ankle joint on dorsiflexion stiffness. Material and methods: The two main ankle ligaments implicated in this type of stiffness, the deep bundle of the posterior tibiotalar ligament (dPTTaL) and the posterior talofibular ligament (PTaFL), were studied. We dissected 16 talocrural joints on fresh cadavers and measured with electronic goniometry coupled with electronic dynamometry their movement in dorsiflexion after section of the dPTTaL in the first group and after section of the PTaFL in the second. Results: The results showed a significant difference (p< 0.0003) between the two populations of ankles. Section of the dPTTaL was more effective against dorsiflexion stiffness than section of the PTaFL, even though the overall benefit in dorsiflexion was less than 10° (mean 7.45 versus 3.45). Combined section of the two ligaments did not provide a statistically significant improvement in the gain in dorsiflextion (p=0.88) compared with isolated section of the two ligaments. Discussion: If limitation of active and passive dorsiflexion persists after classical release or lengthening of the posterior periarticular tendons of the ankle joint, or after gastrocnemius lengthening, our results show that the following surgical step could be meticulous release of the dPTTaL

Introduction This study aims to improve knee arthroplasty prosthetic alignment by determining if an algorithm based on establishing the most prominent points on the medial and lateral malleolion 3D CT scans can be used to establish the true center of the ankle joint. Methods Axial, coronal and sagittal multi-planar reconstructions were generated on 20 ankles. Two observers independently identified the most prominent medial and lateral malleolar points, in the coronal plane, and the highest talar dome point, in the sagittal plane. Ratios were calculated comparing total intermalleolar distance to distance to medial and lateral malleolus, and the ratio of medial to lateral distance. The distance from the true center of the joint, in the sagittal plane, to the computer calculated center was determined. Statistical analysis using ANOVA, paired t-tests and regression analysis was performed. There were 17 normal ankles, two arthritic ankles, and one previously fractured ankle. Results In the coronal plane there was a strong correlation between the measurements of each observer. The mean intermalleolar distance was 70.2 mm (95% CI 68.3–72.0). The strongest correlation was seen in the ratio of lateral distance to total distance (r=0.728) which was 0.57 in normal ankles (95% CI 0.55–0.58). The ratio for arthritic ankles was 0.48 (95% CI 0.46–0.50) and for the fractured ankle 0.57 (95% CI 0.15–0.99). These were significantly different at the five percent level (p< 0.02). The normal ankle ratio was substantiated by regression analysis. There was a poor correlation between the individual measurements in the sagittal plane (r=0.218). The mean distances from the calculated line to the true center were not statistically different with the true center always lying posterior to the calculated line (4.2 mm (95% CI 2.5–5.9) and 2.8 mm (95% CI 1.7–3.8) posterior. For the combined data this means that the mean distance that the true center of the ankle joint’s from a line joining the medial and lateral malleoli is 3.2 mm (95% CI 2.3–4.0 mm). The data was reproducible with a small standard deviation in each plane. Assuming a 300 mm tibial length, angular error in tibial alignment generated by a computer navigation system is less than one degree in both planes. Conclusions The algorithm presented can give accurate measurements of normal ankle joints in knee navigation surgery

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

The ankle joint offers adverse conditions to any prosthetic replacement: high loads on small surfaces, only vague landmarks for the insertion, complex and individually very different functional anatomy. Despite these obstacles many excellent short- and some long-term results have been published, giving little way to a learning curve. This contrasts with our own experiences over at all 29 years now: 24 % failures of cemented two-component EP’s after 14,6 (6,1–21,2) years (n=67) and 8,7 % failures of uncemented tri-component EP’s after 3,7 (0,6–7,6) years (n=92). We analyze and explain special problems and typical failures by a brief historical review of ankle joint replacement: as a logical sequence of various concepts, each of them basing on the knowledge of preceding insufficiencies. The general concern of the functionally useful, but limited mobility after the implantation will be discussed, also on the basis of own early and medium-term results: ROM ranging on average from 26° for TPR-(n=35) and 29° for New Jersey LCS-(n=30) up to 35° for S. T. A. R.-prostheses (n=12). Possible solutions of problems will be considered, respecting assumed causalities. Basing on the literature and own earlier investigations, especially the long-term results will be compared critically. The incertitude of an exact implantation has been partly compensated by the actual „meniscal“ concept of tricomponent prostheses. It should be favourable for their fixation to the bone and moreover reduce polyethylene-wear. But – as before – the discrepancy of high loads on a small area threatens the durability of ankle joint prostheses. Prosthetic replacement has become indispensable in the treatment of painfully destructed ankle joints, but it demands a careful and critical indication

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

Rotational instability is defined as combined medial and lateral ligament instability of the ankle joint. In the case of combined injury to the posterior syndesmosis and posterior joint portion the typical giving-away-symptoms and the therapy resistant complaints are accompanied. In the following prospective study 43 patients between the ages of 16 and 35 with the average age of 23.9 years with posttraumatic chronic joint-instability as well as posterior syndosmosis insufficiency were examined. The treatment of rotational instability was performed by an anchoring technique modified by Broström. The resulting insufficiency of the posterior syndesmosis was treated by a Tight Rope provided by Arthrex. The study was run over 14 months, where only 36 out of 43 patients were available for postoperative follow up. A preoperative baseline 2-view x-ray as well as an MRI was performed in all patients. The operation to establish the stability of the ligaments via anchoring-technique and the treatment of the posterior syndesmosis through Tight-Rope were performed via arthroscopy of the ankle joint with additional inspection of the posterior joint portion. At the same time existent impingements were recessed. In each patient the AOFAS score as an indicator for the treatement outcome and the VAS-score was used as the measurement for the level of pain developement were used. The first exam was performed in preoperative setting followed by subsequent 12 and 24 weeks as well as 12 and 14 months postoperatively. To ensure stability a preoperative x-ray in suppination stress was performed followed by the same type of x-ray 3 months postoperatively. A significant improvement in the above mentioned scores were noted already 3 months after the operation. An improvement in VAS-score of 5.1 points as well as in AOFAS-score of 79% was observed. The degree of Suppination and rotational movement as well as the extent of talus-forfall has reduced significantly. The already improvement of the above scores after 3-month-follow up were consistent even after 14 months. About 90% of patients were satisfied with the outcome of the operation with the “good” and “very good” scores. The complication rate was about 3%. In conclusion, the treatment of posttraumatic mechanical ankle joint instability with posterior syndesmosis injury via anatomic anchoring reconstructive technique and Tight-Rope is considered to be an operative modality with significantly satisfactory results. Keywords: Rotational instability, posterior syndesmosis, stabilisation, tight-rope

Distal tibial fractures may be satisfactorily held in reduction by fine-wire external fixation techniques, avoiding the need for open reduction and internal fixation. However, as the use of external fixation is associated with pin-site infection, extra-articular placement of the wires is recommended. This study assesses the proximal extension of the capsule of the ankle joint in order to provide information on the safety of wire placement for distal tibia fractures. We recruited 7 patients who were electively scheduled for an MRI ankle investigation with the suspicion of osteochondral defect and/or meniscoid lesion. Patients with a history of ankle fracture or ankle surgery were excluded from the study. Just prior to MRI, the ankle joint was injected with 5 to 15 ml of contrast solution (1 mM dimeglumine gadopentetate). Selected fat-saturated T1-weighted MRI scans with sagittal, coronal and axial views were obtained. The site and proximal extent of the capsular reflection with reference to the anterior joint line were measured. All contrast-enhanced MRIs of the ankle joint space were well defined and unambiguous. Proximal capsular extensions above the plane of the anterior joint line were noted at the antero-medial and antero-lateral aspect of the joint (mean 8.9 mm, range 4.9 to 13.4 mm) and at the tibia-fibular recess (mean 18.7 mm, range 13.3 to 23.6 mm), areas that are frequently traversed by wire insertion. Conclusion: This in vivo contrast-enhanced MRI ankle study demonstrates an appreciable capsular extension above the joint line of the ankle. The proximal capsular extensions at the antero-medial and antero-lateral aspect of the joint and at the tibio-fibular recess run the risk of being traversed during fine-wire placement for distal tibia fractures. Surgeons using these techniques should be aware of this anatomy

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

Aims: The purposes of the current retrospective study were to evaluate the outcome of a consecutive series of supramalleolar osteotomies and to identify the influence of the technique (opening versus closing wedge) on the outcome and the union rate. Methods: In a five year period, we performed a supra-malleolar osteotomy for the correction of distal tibial mechanical malalignment of at least 10°, with concomitant pain and with or without radiographic evidence of arthritic changes, or as an alternative to other common procedures, for the treatment of a small group of patients with degenerative changes of the ankle joint. Results: There were 14 patients (15 feet) with an average follow up of 31.1 months. All osteotomies healed at an average time of 13.6 weeks. The average AOFAS score improved from 53.8 to 87 points, the average Takakura score from 56.7 to 82 and the average pain score from 13.5 to 31.4. In the presence of deformity the average values of TAS and TLS angles were significantly improved. The radiographic degenerative changes in the ankle joint showed no evidence of progression. The choice of technique did not influence the clinical- radiographic outcome and the healing time of the osteotomy. Conclusions: Supramalleolar osteotomy is a useful procedure to: a. reconstruct the normal mechanical environment in malunion preventing or decelerating any long term deleterious effects and improving pain and function levels, and b. to shift and redistribute loads in the ankle joint in an effort to protect the articular cartilage from further degenerative process