Abstract
Detection of syndesmotic ankle instability remains challenging in clinical practice due to the limitations of two-dimensional (2D) measurements. The transition to automated three-dimensional ...(3D) measurement techniques is on the verge of a breakthrough but normative and side-to-side comparative data are missing. Therefore, our study aim was two-fold: (1) to establish 3D anatomical reference values of the ankle syndesmosis based on automated measurements and (2) to determine to what extent the ankle syndesmosis is symmetric across all 3D measurements. Patients without syndesmotic pathology with a non-weight-bearing CT scan (NWBCT; N = 38; Age = 51.6 ± 17.43 years) and weight-bearing CT scan (WBCT; N = 43; Age = 48.9 ± 14.3 years) were retrospectively included. After training and validation of a neural network to automate the segmentation of 3D ankle models, an iterative closest point registration was performed to superimpose the left on the right ankle. Subsequently, 3D measurements were manually and automatically computed using a custom-made algorithm and side-to-side comparison of these landmarks allowed one to investigate symmetry. Intra-observer analysis showed excellent agreements for all manual measurements (ICC range 0.85–0.99) and good (i.e. < 2.7° for the angles and < 0.5 mm for the distances) accuracy was found between the automated and manual measurements. A mean Dice coefficient of 0.99 was found for the automated segmentation framework. The established mean, standard deviation and range were provided for each 3D measurement. From these data, reference values were derived to differ physiological from pathological syndesmotic alignment. Furthermore, side-to-side symmetry was revealed when comparing left to right measurements (P > 0.05). In clinical practice, our novel algorithm could surmount the current limitations of manual 2D measurements and distinguish patients with a syndesmotic ankle lesion from normal variance.
Objective
The role of the syndesmotic ankle ligaments as extrinsic stabilizers of the distal tibiofibular joint (DTFJ) has been studied extensively in patients with high ankle sprains (HAS). However, ...research concerning the fibular incisura as intrinsic stabilizer of the DTFJ has been obscured by a two-dimensional assessment of a three-dimensional structure. Therefore, we aimed to compare the morphometry of the incisura fibularis between patients with HAS and a control group using three-dimensional radiographic techniques.
Materials and methods
Fifteen patients with a mean age of 44 years (SD = 15.2) diagnosed with an unstable HAS and twenty-five control subjects with a mean age of 47.4 years (SD = 6.5) were analyzed in this retrospective comparative study. The obtained CT images were converted to three-dimensional models, and the following radiographic parameters of the incisura fibularis were determined using three-dimensional measurements: incisura width, incisura depth, incisura height, incisura angle, incisura width-depth ratio, and incisura-tibia ratio.
Results
The mean incisura depth (M = 4.7 mm, SD = 1.1 mm), incisura height (M = 36.1 mm, SD = 5.3 mm), and incisura angle of the control group (M = 137.2°, SD = 7.9°) differed significantly from patients with a HAS (resp., M = 3.8 mm, SD = 1.1 mm; M = 31.9 mm, SD = 3.2 mm; M = 143.2°, SD = 8.3°) (
P <
0.05). The incisura width, incisura width-depth ratio, and incisura-tibia ratio demonstrated no significant difference (
P >
0.05).
Conclusion
Our three-dimensional comparative analysis has detected a shallower and shorter fibular incisura in patients with HAS. This distinct morphology could have repercussion on the intrinsic or osseous stability of the DTFJ. Future prospective radiographic assessment could determine to what extend the fibular incisura morphology contributes to syndesmotic ankle injuries caused by high ankle sprains.
Category:
Trauma; Ankle
Introduction/Purpose:
Forced external rotation is hypothesized as the key mechanism of syndesmotic ankle injuries, inducing a three-dimensional deviation from the normal ...distal tibiofibular joint alignment. These lesions, especially when subtle, present a deceitful diagnostic challenge. Current diagnostic imaging modalities are impeded by a two-dimensional assessment, without considering ligamentous stabilizers. Accurate diagnosis of syndesmotic lesions should involve 3D weightbearing osseous imaging in combination with - preferably automated- inclusion of patient-specific ligamentous information. Therefore, our aim is two-fold: (1) to construct a three-dimensional articulated statistical shape model of the normal distal tibiofibular joint with inclusion of ligamentous morphometry and (2) to detect differences in predicted syndesmotic ligament length of patients with syndesmotic lesions with respect to normative data.
Methods:
Training data comprised non-weightbearing CT scans from asymptomatic controls (N= 76, Mean age 63 +/- 19 years), weightbearing CT scans from patients with syndesmotic ankle injury (N = 13, Mean Age 35 +/- 15 years) and their weightbearing healthy contralateral side (N = 13). CT scan segmentation was used to generate 3D bone models in the control and patient group. All ankles were aligned based on the tibia. Path and length of the syndesmotic ligaments were predicted using a discrete element model, wrapped around bony contours. Statistical shape model evaluation was based on accuracy, generalization and compactness. The predicted ligament length in patients with syndesmotic lesions was compared to healthy controls by use of two-tailed Two- Sample student's t-test.
Results:
Our presented skeletal shape model described the training data with an accuracy of 0.23 +/- 0.028 mm. Mean prediction accuracy of ligament insertions was 0.53 +/- 0.12 mm. Mean length of the Anterior inferior tibiofibular ligament was 12.26 +- 1.89mm for the control cases, 12.32 +- 1.58 mm for the contralateral cases and 14.13 +- 1.48 mm for the cases with syndesmotic lesions. Statistically significant differences were found between the latter two (95% CI 0.323.29, p = 0.017) There was a significant correlation between presence of syndesmotic injury and the positional alignment between the distal tibia and fibula (r = 0.873, p < 0,001).
Conclusion:
Statistical shape modelling combined with patient-specific ligament wrapping techniques can facilitate the diagnostic workup of syndesmotic ankle lesions under weightbearing conditions. In doing so, an increased anterior tibiofibular distance was detected, corresponding to an 'anterior open-book injury' of the ankle syndesmosis as a result of anterior inferior tibiofibular ligament elongation/rupture (Figure 1).
Category:
Trauma; Ankle
Introduction/Purpose:
Ankle fractures represent an increasingly common injury world-wide and the decision for operative fixation often hinges on the definition of acceptable ...stability. Mortise malalignment has generally been considered as the main predictive factor leading to poorer outcomes and the development of post-traumatic osteoarthritis. Following pioneering work by Ramsey & Hamilton, 1-2 mm of lateral talar displacement has commonly been regarded as a cutoff value for surgical decision making. However, isolated lateral talar translation (as studied in previous works) does not fully replicate the multidirectional joint subluxation seen in ankle fractures. Furthermore, previous studies have been limited by low fidelity methodologic techniques. Therefore, the aim of this study was to analyze the influence of multiplanar talar displacement on tibiotalar contact mechanics utilizing finite element analysis (FEA).
Methods:
19 patients having undergone advanced computed tomography (CT) scanning of the ankle were included. A female patient (age 18 years, weight 60 kg) without preexisting articular ankle pathology underwent a weightbearing CT-arthrogram of the left ankle. Additionally, 18 ankles derived from the contralateral healthy side in patients who underwent bilateral weightbearing CT scans (WBCT ) for evaluation of a contralateral ankle fracture were included (mean age = 38.70 years, mean weight = 80.00 kg, left/right: 9/9). Segmentation of the WBCT images into 3D models of bone and cartilage was performed semi-automatically, while on the non-arthrography WBCT images, personalized cartilage layers were modeled based on a previously validated methodology. 3D multiplanar talar displacement was simulated to investigate their respective influence on the tibiotalar contact mechanics. Tibial peak contact stress, talar peak contact stress and contact area were extracted from the FEA models for each condition.
Results:
The talar peak contact stress (in MPa), tibial peak contact stress (in MPa) and contact area (in mm²) for each condition are presented in Table 1. Overall, both the mean and peak contact stress for the talus and tibia incrementally increased when the talus was displaced, for all directions. Correspondingly, the contact area incrementally decreased. Contact stress maps of the talus and tibia were computed for each of the conditions, demonstrating unique patterns of pressure derangement. 1 mm of lateral translation resulted in 11% increase in peak contact pressure and a 12% decrease in contact area. External rotation exhibited the greatest influence on contact stress, reaching a peak talar stress of 510% above baseline after 20 degrees of external talar rotation.
Conclusion:
In this study, we were able to build on the paradigm of prior uniplanar cadaveric studies and provide a multiplanar mortise malalignment model. The use of advanced computational technologies allowed for more precise quantitative evaluation of articular contact mechanics. With lateral talar translation, our model demonstrated less dramatic increases in tibiotalar contact area compared to previous studies, whereas external rotation had the largest effect regarding pathologic joint loading. Clinically, this study provides a novel understanding of the mechanical sequelae of 3D talar displacement and the importance for adequate mortise alignment.
Category:
Sports; Trauma
Introduction/Purpose:
Syndesmotic ankle injuries are present in one-fourth of all ankle trauma and may lead to syndesmotic instability or posttraumatic ankle osteoarthirtis ...on the long term. At present, they continue to impose a diagnostic dilemma our clinical practice. While magnetic resonance imaging lacks application of load to the ankle joint, plain weightbearing radiographs are skewed by superposition of the osseous structures. The recent advent of weightbearing cone-beam CT (WBCT) overcomes these drawbacks by imaging both ankles during bipedal stance. However, it remains debated whether syndesmotic ankle injuries should be imaged under weightbearing conditions and/or during application of external rotation. Therefore, we aimed to implement both weightbearing and external rotation in the assessment of syndesmotic ankle injuries using WBCT imaging combined with 3D measurement techniques.
Methods:
In this retrospective study, patients with an acute syndesmotic ankle injury were analyzed using a WBCT (N= 21; Age= 31.64±14.07 years old). Inclusion criteria were an MRI confirmed syndesmotic ligament injury imaged by a WBCT of the ankle during weightbearing and combined weightbearing-external rotation. Exclusion criteria consisted of fracture associated syndesmotic injuries. For the external rotation protocol, the patient was asked to internally rotate the shin while ensuring that the foot remained firmly plantigrade until pain (Visual Analogue Scale > 8/10) or a maximal range of motion was reached. 3D models were generated from the CT slices. Tibiofibular displacement and Talar Rotation were quantified by automated 3D measurements using a custom-made Matlab® script; Anterior Tibiofibular distance (ATFD), Alpha angle, posterior Tibiofibular distance (PTFD) and Talar rotation (TR) angle in comparison to the contralateral non-injured ankle.
Results:
The difference in neutral-stressed Alpha angle and ATFD showed a significant difference between patients with a syndesmotic ankle lesion and contralateral control (P = 0.046 and P = 0.039, respectively). The difference in neutral-stressed PTFD and TR angle did not show a significant difference between patients with a syndesmotic ankle lesion and healthy ankles (P = 0.492; P = 0.152, respectively).
Conclusion:
Application of combined weightbearing-external rotation reveals an increased ATFD in patients with syndesmotic ligament injuries (Figure 1). This study provides the first insights based on 3D measurements to support the potential relevance of applying external rotation during WBCT imaging. In clinical practice, this could enhance the current diagnostic accuracy of subtle syndesmotic instability in a non-invasive manner. However, future studies are required to determine cut-off values that may indicate the amount of displacement that might lead to chronic instability and require a certain type of treatment strategy.
Introduction/Purpose:
Minimal invasive proximal metatarsal osteotomy (PMO) offers a successful approach for addressing metatarsus adductus while avoiding exposure of all metatarsals, thereby reducing ...the risk of complications such as wound infections and non-unions. An important hurdle is the absence of direct visualization for precise osteotomy placement. Staying within the tarsometatarsal (TMT) capsule enhances the chances of better union due to improved blood supply, although operating outside the capsule can aid in correcting more significant deformities. Despite having a macroscopic understanding of anatomical locations through specimens, there has been a lack of prior reports on their mapping in fluoroscopic images. Developing such maps could significantly improve the navigational skills of surgeons. This study aims to present heatmaps that illustrate the positions of distal attachments of TMT capsules.
Methods:
A total of nine specimens below the knee, devoid of any prior bone or joint abnormalities, were thawed a day prior to the experiments. After dissecting the dorsal skin, neurovascular structures, and tendons, only the bones and capsules remained. Flexible wires were placed alongside the distal edges of TMT capsules, encompassing the 1st, 2nd, 3rd, and 4th tarsometatarsal joints. This arrangement aimed to make the paths of these capsules visible when observed through X-ray imaging. The wires were then securely attached to the structures using a soft tissue adhesive. Fluoroscopy images were captured, including a calibration marker of a known diameter, in addition to taking macroscopic photographs. The specific coordinates of these structures were marked in a three-dimensional space within specialized 3D software. Subsequently, these coordinates were imported into a custom-designed Python script crafted for the purpose of generating heatmaps.
Results:
The heatmaps were successfully produced encompassing all TMT capsules spanning from the 1st to the 4th, and these were overlaid onto an anteroposterior fluoroscopy image of the foot (refer to Figure 1). This gradient of colors serves as a visual representation of differing magnitudes, with red denoting the most prevalent areas of the distal attachment of the TMT capsule, while blue corresponds to lower occurrences.
Conclusion:
These heatmaps not only showcase the predominantly observed sites of distal TMT attachments, depicted in red, but also signify diverse deviations, identifiable by the presence of less frequent zones indicated in blue. Consequently, surgeons are advised to consider these findings while planning their osteotomies based on their preferred positions. By furnishing surgeons with an extensive heatmap that outlines potential tarsometatarsal capsule insertions, this research not only furnishes them with a dependable guiding resource but also establishes a foundation for more assured and prosperous minimally invasive midfoot fusion procedures.
Figure 1: The heatmap of 1st to 4th tarsometatarsal capsules on AP fluoroscopy.
Category:
Hindfoot; Sports
Introduction/Purpose:
Posterior heel pain at the Achilles tendon insertion is a prevalent and debilitating condition that is not yet fully understood. It results from a ...combination of bony and soft tissue abnormalities, including insertional Achilles tendinopathy, retrocalcaneal bursitis, and posterosuperior bony prominence. While the most commonly used surgical technique for treatment is debridement and reattachment of the tendon, dorsal closing wedge calcaneal osteotomy (DCWCO) has recently gained popularity. In this meta-analysis, we aimed to analyze the published literature related to both surgical techniques and compare their outcomes. Our hypothesis was that DCWCO can provide similar clinical outcomes with a lower complication rate.
Methods:
We conducted a literature search in Medline, Embase, and Scopus databases. Clinical studies reporting at least one of the clinical outcomes among AOFAS score and complications, with an open technique and sufficient data to extract and pool, were included. The extraction was made by two users using the Covidence platform. Studies with less than 10 patients or less than 12 months follow-up were excluded. Initial search yielded 329 papers, and after excluding duplicates and irrelevant studies, 43 papers were left. After a full-text review of these 43 papers, we found 15 papers eligible for meta-analysis. We used the Modified Coleman Methodology to assess the quality of papers.
Results:
Out of the 15 articles, seven included reattachment patients, while eight included DCWCO patients. 171 feet underwent reattachment, while 239 feet underwent DCWCO. The average follow-up of patients was significantly higher in the DCWCO group (42.2 months) than reattachment group (23.2 months). The average AOFAS score improvement was similar between the groups. The total complication numbers were 30 (16.6%) in the reattachment group and 28 (9.2%) in the DCWCO group, but the difference did not reach significance since the confidence intervals were overlapping. However, wound complications were significantly more common in Reattachment group (10.1%) compared to DCWCO (2.5%). The number of revision surgeries and neurological complications (sural neuritis, hypersensitivity, etc.) were similar between the groups. The average AOFAS score improvement was similar between the groups.
Conclusion:
Both techniques yielded comparable clinical outcomes. The overall complication rate was similar, but DCWCO exhibited a lower wound complication rate than reattachment. Therefore, the study results imply that DCWCO can provide similar clinical outcomes with fewer wound complications. However, further well-designed studies are necessary to reach a definitive conclusion on this matter and compare both techniques in the same study setting.
Category:
Hindfoot; Sports
Introduction/Purpose:
The use of a dorsal closing wedge calcaneal osteotomy (DCWCO) in the treatment of insertional Achilles tendinopathy (IAT) has recently gained ...popularity. The anatomical changes imposed by the osteotomy are believed to improve both the biological and mechanical processes involved in IAT. However, the impact of shortening the Achilles leverage arm after DCWCO and the full impact of DCWCO on foot anatomy and function is not well understood. This study aimed to examine the effects of DCWCO on the 3D alignment and biomechanics of the foot and ankle in IAT patients through simulated models of DCWCO. The hypothesis was that DCWCO would significantly impact foot alignment and decrease gastrocsoleus lever arm.
Methods:
Six weightbearing ankle CTs of patients with IAT were identified from the clinical database. Bone segmentation was performed and DCWCOs were conducted in standardized planes with six variations, resulting in a total of 36 foot models. Two plantar osteotomy starting points were defined as 1-cm anterior (posterior osteotomy) and 2-cm anterior (anterior osteotomy) to the most plantar point of calcaneus. The osteotomies were extended to dorsal surface at 1-cm anterior to posterosuperior calcaneus with 6, 10, or 14-mm wedges anteriorly. After the osteotomies, the posterior part of the calcaneus was rotated around the plantar starting point until proper bone contact was achieved. Achilles reconstruction was also performed using pre-defined Achilles insertion points. All models were then transferred to a MATLAB-based algorithm for automated measurements. These measurements included talocalcaneal, calcaneal pitch, Böhler, and Achilles tendon sagittal angles, Achilles moment arm, Achilles- posterosuperior calcaneus distance, and difference in soleus-Achilles length.
Results:
Anteriorly placed osteotomy caused more significant decrease in the Böhler angle (p < 0.001). Evaluation of the posteriorly placed osteotomy separately showed no significant decrease in the Böhler angle for patients with more than 30- degrees of preoperative Böhler angle (p=0.26). However, patients with a preoperative Böhler angle less than 30-degrees showed a significant decrease, approaching values close to 5-degrees (p=0.004). Gastrocsoleus moment arm decrease was found to be 2-3% by using force/moment equation. The change in the distance between Achilles tendon and the posterosuperior calcaneus was similar between anterior and posterior osteotomies, with less than 3-mm in a 6-mm wedge and more than 5-mm in a 10-mm wedge osteotomy. The calculations showed that ankle dorsiflexion can increase by one degree for each mm of resection.
Conclusion:
An anteriorly placed starting point for a DCWCO can negatively affect foot alignment and offer limited benefits for Achilles decompression. If the preoperative Böhler angle is less than 30, a DCWCO can significantly decrease the Böhler angle, potentially putting the subtalar joint at risk for arthritis by increasing the load as reported by some finite element studies. The maximum decrease in gastrocsoleus power is less than 3%, which may be clinically insignificant. A posterior starting point with 10- mm wedge can be adequate to move Haglund around 5-mm anteriorly and can move Achilles insertion 10-mm superiorly to decrease tension.
