Weightbearing CT Scans Research Articles

Retrospective chart review: Weightbearing CT scans and the measurement of the Lisfranc ligamentous complex

BackgroundLisfranc Ligamentous Complex (LLC) injuries are commonly misdiagnosed due to their unreliable projection on plain films. Weightbearing CT (WBCT) scans are a relatively new imaging modality that has not yet been utilized to establish widely referenced baseline anatomic positions. MethodsA retrospective chart review was conducted of patients who had undergone weightbearing CT of the bilateral lower extremities with one-hundred and twelve being included (56 patients). Measurements of the Lisfranc joint were collected by two independent reviewers. Uninjured symmetric anatomy was used to describe a baseline for normal anatomic variation and to evaluate for sex-based or age-related differences. These measurements were then compared against the injured side. ResultsIn patients without Lisfranc injury, the 1st metatarsal base to 2nd metatarsal base distance (Base M1-M2) was 2.7 + /− 0.7 mm; 2nd metatarsal base to medial cuneiform (M2-C1) was 3.7 + /− 0.7 mm; intercuneiform distance was 1.2 + /− 0.3 mm; and sagittal descent 12.2 + /− 5.4 mm. Patients with injury to LLC had a larger M1-M2 base distance (Δ = 0.5903, p < 0.0001) and M2-C1 interval (Δ = 1.8008, p < 0.0001) compared to uninjured side. Males had significantly higher M2-C1 (p = 0.0031), intercuneiform distance (p = 0.0039), and sagittal descent (p = 0.0008) compared to female patients. No significant differences were found between left versus right side in any of the measurements. Intercuneiform distance (p = 0.0039) was found to significantly decrease as age increased, while sagittal descent significantly increased with increased age (p = 0.0066). ConclusionWeightbearing CT has high utility in identification of Lisfranc injuries particularly when comparing injured and uninjured sides, which may be its greatest utility in defining injuries. This is evident in the excellent diagnostic ability of the M2-C1 measurement. By defining baseline anatomic measurements for Lisfranc complex parameters in our patient population, we provide normal parameters for comparison when evaluating potential subtle injuries. Level of evidenceIII

Reliability improvement in Hallux Valgus measurement using weight-Bearing CT scan.

Background: Radiographic assessment of hallux valgus is an essential process. Residual rotational deformity was shown associated with higher recurrent rate. This study aims to comprehensively assess reliability of measurement of various parameters from plain films and weight-bearing CT scan. Methods: A total of 40 pre-operative plain radiographs, 40 post-operative plain radiographs, and 37 weight-bearing CT scan were evaluated to determine reliability of hallux valgus parameters. Results: TSP and head shape representing coronal plane deformity showed lower inter-observer reliability compared to other parameters using for transverse plane evaluation especially in post-operative period. (post-op TSP amongst 3 assessors: κ = 0.386, 0.520, 0.340; post-op head shape: κ = 0.374, 0.375, 0.295) Using α angle for evaluation 1st metatarsal rotation in weight-bearing CT scan demonstrated very good reliability for inter-observer (ICC = 0.853 (95% CI = 0.715-0.925)) and intra-observer (ICC = 0.902 (95% CI = 0.844-0.939)). Conclusion: Weight-bearing CT scan can improve reliability in post-operative coronal plane assessment.

Impact of First Metatarsal Hyperpronation on First Ray Alignment: A Study in Cadavers.

There is increased evidence of first metatarsal hyperpronation in patients with hallux valgus, but its impact on the stability of the first metatarsophalangeal and metatarsosesamoid joints is unknown. A previous biomechanical study showed that an increase in hallucal pronation might lead to medial soft tissue failure of the first metatarsophalangeal joint. Conversely, dynamic studies on hallux valgus have shown that the first tarsometatarsal joint moves in supination during weightbearing, and supination was associated with an increase in the intermetatarsal angle (IMA) and hallux valgus angle (HVA). (1) Does an increase in first metatarsal pronation cause an increase in hallucal pronation? (2) Can an intrinsic increase in first metatarsal pronation lead to first ray supination during weightbearing? (3) Can a combination of intrinsic first metatarsal hyperpronation and first metatarsophalangeal medial soft tissue failure increase supination of the first ray during weightbearing? (4) Is first ray supination during weightbearing associated with an increase in the IMA and HVA? Twelve transtibial, nonpaired cadaver specimens without deformities were used. Each specimen underwent six weightbearing CT scans under different conditions. The first three CT examinations were performed without any osteotomy of the first metatarsal. The first was a simulated nonweightbearing condition. The second was a simulated weightbearing condition. The third was a simulated weightbearing condition with medial soft tissue release. Subsequentially, a 30° pronation osteotomy of the first metatarsal was performed, and the same sequence of weightbearing CT images was obtained. On each weightbearing CT image, the HVA, IMA, sesamoid rotation angle, metatarsal pronation angle (MPA), metatarsosesamoid rotation angle, and hallucal pronation (HP) were measured. Motions were calculated based on the differential values of these angular measurements produced by the six different conditions (weightbearing, medial soft tissue release, 30° pronation osteotomy, and combinations of these conditions). We compared means using a t-test for normally distributed variables and the Mann-Whitney U test for nonnormally distributed variables. Correlations were assessed with Pearson product-moment correlation coefficients. We found that 30° pronation osteotomy of the first metatarsal increased the MPA and HP by 28° ± 4° and 26° ± 6°, respectively, in the nonweightbearing condition. No differences between the increase in MPA and the increase in HP were noted (mean difference 2° [95% CI -1° to 5°]; p = 0.20). Therefore, an increase in first metatarsal pronation caused an increase in hallucal pronation. When a 30° pronation osteotomy of the first metatarsal was performed, the first ray motion during weightbearing went from pronation to supination (4° ± 2° in pronation without osteotomy versus 4° ± 2° in supination after the osteotomy, mean difference 8° [95% CI 6° to 9°]; p < 0.001). Therefore, an intrinsic increase in pronation of the first metatarsal led to a first ray supination motion during weightbearing. When a first metatarsophalangeal medial soft tissue release was performed in addition to the 30° osteotomy of the first metatarsal, the supination motion of the first ray increased (4° ± 2° without medial soft tissue release versus 11° ± 7° after the release, mean difference 8° [95% CI 3° to 12°]; p = 0.003). Therefore, a combination of intrinsic first metatarsal hyperpronation and first metatarsophalangeal medial soft tissue failure increased supination of the first ray during weightbearing. Regarding static angular measurements, the HVA and IMA were not correlated with the MPA (ρ = 0.20; p = 0.09 and ρ = 0.22; p = 0.07, respectively). Regarding motions, as the HVA and IMA increased from nonweightbearing to weightbearing the pronation decreased, with strong correlations (ρ = -0.82; p < 0.001 and ρ = -0.77; p < 0.001, respectively). Therefore, a first ray supination during weightbearing was associated with an increase in the HVA and IMA. The combination of first metatarsal intrinsic hyperpronation and first metatarsophalangeal medial soft tissue failure led to a hallux valgus deformity in this cadaveric study. The static measurement of first metatarsal head pronation relative to the ground (MPA) did not reflect the real intrinsic pronation of the first ray, and foot and ankle specialists should be careful when interpreting these measurements. Hallux valgus is a dynamic condition, and the deformity could be more correlated with motions during weightbearing than with plain static measurements. First ray supination compensating for first metatarsal intrinsic hyperpronation might be an important factor in the hallux valgus pathogenesis. Further in vivo studies involving nonweightbearing and weightbearing comparative assessments of hallux valgus and controls should be performed to confirm this pathomechanism.

Relationship of Axial Alignment and Patient-Reported Outcomes in Patients with Total Ankle Arthroplasty under Weightbearing CT Scan

Category:Ankle ArthritisIntroduction/Purpose:Axial alignment (rotation) in total ankle replacement has come to surgeons' attention in recent publications. Unfortunately, most of the previously published data present information from non weight-bearing computed tomography (WBCT) scans or lack a correlation with patient-reported outcomes (PROs). To the author's knowledge, axial alignment is not completely understood in its current form and its relation to PROs. Therefore, our objective is to propose a standardization in measurements of axial alignment in prosthesis components under weight-bearing CT examination and to correlate it with patient-reported outcomes.Methods:After obtaining IRB approval, our prospectively collected surgical database was queried for patients undergoing Total Ankle Arthroplasty (TAA). Patients were included if they had preoperative weight-bearing X-rays, non-WBCT scan, pain evaluation (VAS pain score), preoperative functional scales (SF-36, SFMA, FAAOS, and FAAM) and underwent TAA using an Infinity Prosthesis with standard instrumentation. Patients were excluded if they had less than a one-year postoperative period, had revision surgery, or declined to participate. Twenty five patients met the inclusion/exclusion criteria. All patients were brought back to the clinic for weight-bearing CT scan, pain evaluation, repeat functional scales, and to sign informed consent for the specific needs of this study. Three fellowship-trained musculoskeletal radiologists realized all measurements in two time-frames (coronal, sagittal and axial alignment), separated for one month each. Cohen's inter and intraclass coefficients were calculated to estimate the amount of agreement that occurred by chance.Results:Average age was 64.5 years, Average BMI was 28. Good to excellent intraobserver reliability (ICC 0.891 , 0.750, 0.902 respectively) and good interobserver reliability (ICC 0.822) were reported. Component malrotation was seen in five patients (20%), defined as a relative axial rotation between components of 5 degrees or greater. There was a statistically significant correlation between coronal, sagittal and axial alignment measurements and FAAM scale (p<0.05). There was a positive trend in the association between malrotation and PROs, but this was not statistically significant (p=0.09).Conclusion:This is the first study to correlate axial component alignment in total ankle replacement with patient-reported outcomes. Success in TAA is in direct relationship with achieving neutral alignment at the ankle and hindfoot. Axial alignment is statistically correlated with PROs. There was a positive trend in the association between malrotation and PROs, however this study didn't show a statistical correlation.

Impact of Weber B Fracture Displacement on Medial Clear Space Volume: How Much Displacement Matters?

Category:Ankle; Sports; TraumaIntroduction/Purpose:Numerous radiographic studies examining Weber B fibular fractures demonstrate no change in tibiotalar contact area until the deltoid ligament is disrupted. In contrast, more recent studies using weight-bearing CT scan (WBCT) and 3D volume analysis suggest that medial clear space (MCS) volume can in fact increase in the setting of a Weber B fibular fracture even if initial radiographs are reassuring, possibly due to a loss of fibular buttress. This study aims to evaluate the ability of WBCT to quantify the impact of isolated Weber B fractures on MCS volume (3D), as well as understand the implication of increasing fibular displacement among patients with symmetric MCS distance (1D) on initial radiographs.Methods:The study group included 18 patients with unilateral Weber B ankle fractures who underwent preoperative bilateral foot and ankle WBCT. The control group consisted of 60 patients without ankle injury who underwent similar imaging.Measurements on WBCT images included: 1) MCS distance, 2) syndesmotic area, 3) anterior, middle, and posterior distal tibiofibular distance, 4) fibular rotation, 5) distance from fibular tip to plafond, and 6) fibular fracture displacement. Additionally, volumetric measurements included: 1) MCS volume 2) syndesmotic joint volume from the tibial plafond extending to 3cm and 5 cm proximally, and 3) lateral clear space volume were calculated. Area under the receiver operating characteristic (ROC) curve analysis and Delong test were used, and optimal cutoff values to distinguish between stable and unstable Weber B fractures without syndesmotic instability and MCS widening were determined using Youden's J statistic.Results:Among patients with unilateral Weber B ankle fractures, all WBCT measurements showed no side-to-side difference in any parameter, except MCS volume (p-values <0.001). When compared to the uninjured side, fibular displacement up to 2cm and up to 4cm increased lateral MCS volume by 37.1% (0.23cm3) and 51.8% (0.3cm3), respectively. Based on ROC analysis and Youden's J statistic, the optimal threshold for differentiating stable from an unstable Weber B fracture was 2.3 mm of displacement (AUC 0.81; sensitivity 77.8%; specificity 80%). The control group showed no difference in any of the measurements between the two sides.Conclusion:When using WBCT, 3D MCS volume increases significantly with Weber B fibular fractures, even if 1D distance measurements at the medial clear space are reassuring. This is especially true with fibular displacement greater than 2.3mm and may have an important role in the management of SER II ankle fractures.

Statistical shape model-based tibiofibular assessment of syndesmotic ankle lesions using weight-bearing CT.

Forced external rotation is hypothesized as the key mechanism of syndesmotic ankle injuries, inducing a three-dimensional deviation from the normal distal tibiofibular joint (DTFJ) alignment. However, current diagnostic imaging modalities are impeded by a two-dimensional assessment, without considering ligamentous stabilizers. Therefore, our aim is threefold: (1) to construct an articulated statistical shape model of the normal DTFJ with the inclusion of ligamentous morphometry, (2) to investigate the effect of weight-bearing on the DTFJ alignment, and (3) to detect differences in predicted syndesmotic ligament length of patients with syndesmotic lesions with respect to normative data. Training data comprised non-weight-bearing CT scans from asymptomatic controls (N = 76), weight-bearing CT scans from patients with syndesmotic ankle injury (N = 13), and their weight-bearing healthy contralateral side (N = 13). 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 with healthy controls. With respect to the first aim, 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. In accordance with the second aim, our results showed an increased tibiofibular diastasis in healthy ankles after weight-bearing. Concerning our third aim, a statistically significant difference in anterior syndesmotic ligament length was found between ankles with syndesmotic lesions and healthy controls (p = 0.017). There was a significant correlation between the presence of syndesmotic injury and the positional alignment between the distal tibia and fibula (r = 0.873, p < 0,001). Clinical Significance: Statistical shape modeling combined with patient-specific ligament wrapping techniques can facilitate the diagnostic workup of syndesmosic ankle lesions under weight-bearing 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.

Semi-automatic software-based 3D-angular measurement for Weight-Bearing CT (WBCT) in the foot provides different angles than measurement by hand

BackgroundThe purpose of this study was to compare semi-automatic software-based angular measurement (SAM) with previously validated measurement by hand (MBH) regarding angle values and time spent for the investigator for Weight-Bearing CT (WBCT). MethodsIn this retrospective comparative study, five-hundred bilateral WBCT scans (PedCAT, Curvebeam, Warrington, PA, USA) were included in the study. Five angles (1st - 2nd intermetatarsal angle (IM), talo-metatarsal 1-angle (TMT) dorsoplantar and lateral projection, hindfoot angle, calcaneal pitch angle) were measured with MBH and SAM (Bonelogic Ortho Foot and Ankle, Version 1.0.0-R, Disior Ltd, Helsinki, Finland) on the right/left foot/ankle. The angles and time spent of MBH and SAM were compared (t-test, homoscesdatic). ResultsThe angles differed between MBH and SAM (mean values MBH/SAM; IM, 9.1/13.0; TMT dorsoplantar, −3.4/8.2; TMT lateral. −6.4/−1.1; hindfoot angle, 4.6/21.6; calcaneal pitch angle, 20.5/20.1; each p < 0.001 except the calcaneal pitch angle, p = 0.35). The time spent for MBH / SAM was 44.5 ± 12 s / 12 ± 0 s on average per angle (p < 0.001). ConclusionsSAM provided different angles as MBH (except calcaneal pitch angle) and can currently not be considered as validated angle measurement method (except calcaneal pitch angle). The investigator time spent is 73% lower for SAM (12 s per angle) than for MBH (44.5 s per angle). SAM might be an important step forward for 3D-angle measurement of WBCT when valid angles are provided.

Crista Volume Measured from 3D Reconstructions Shows a Relationship to Sesamoid Station

Category:BunionIntroduction/Purpose:The hallux valgus (HV) deformity results in progressive subluxation of the sesamoids from their position (station) under the plantar surface of the first metatarsal head. This subluxation may result in erosion of the crista that separates the sesamoid grooves due to contact with the tibial sesamoid during weightbearing. While previous work using weightbearing CT (WBCT) scans has suggested that tibial sesamoid position is associated with degenerative change of the sesamoid metatarsal joint (Katsui FAI), no studies have quantified the relationship between sesamoid metatarsal degenerative changes and sesamoid subluxation. The purpose of the current investigation is to examine the relationship of the volume of the crista to first metatarsal pronation and sesamoid station, using three-dimensional models of patients' deformities created from WBCT scans.Methods:Thirty-nine HV patients and nine normal subjects underwent weightbearing or simulated weightbearing CT (WBCT) imaging. Crista volume was determined using a line drawn to connect the nadir of each sulcus on either side of the intersesamoidal crista for the length of the crista (Figure 1). The Mann-Whitney U test was used to compare mean crista volume between HV and normal patients. WBCT scans were used to establish sesamoid position using a four-stage scale (Kim FAI 2015) and quantify first metatarsal pronation using 3D reconstructions as previously described (Campbell FAI 2018). Single-factor analysis of variance (ANOVA) tests were used to compared the crista volume and pronation angle between the four sesamoid stations. A linear regression was performed to determine whether crista volume was associated with the pronation angle. Spearman's rank coefficient (r) was used to test the relationship of the sesamoid station against the crista volume and pronation angle.Results:The mean crista volume in HV patients was 80.10 mm3 +- 35 mm3 and in normal subjects was 150.64 mm3 +- 24 mm3, which differed significantly between the two groups (P<0.001). Mean crista volumes were found to be statistically significantly different between the sesamoid stations (P<0.001) with decreasing crista volumes significantly and strongly correlated with increasing sesamoid station (r = -0.80, P<0.001). The mean standard deviation values of the crista volume by sesamoid station were 154.4 mm3 +- 18.7 mm3 for station zero, 98.19 mm3 +- 26.9 mm3 for station one, 78.45 mm3 +- 30.1 mm3 for station two, and 44.77 mm3 +- 13.5 mm3 for station three. There was no difference in the mean pronation angle between the four sesamoid stations (P=0.37). Additionally, no statistically significant relationship was found between sesamoid station and pronation angle. The pronation angle was not associated with crista volume (P=0.52).Conclusion:Our study found that HV patients have significantly lower mean crista volumes compared to normal patients. Crista volume was strongly correlated with sesamoid subluxation/station, suggesting that tibial sesamoid subluxation results in erosion of the crista. In contrast, the pronation deformity was not associated with crista volume demonstrating that the degenerative changes of the sesamoid metatarsal are not related to the rotational deformity of the first metatarsal. This supports the hypothesis that tibial sesamoid subluxation may result in osteoarthritis of the sesamoid metatarsal joint and may be an overlooked source of pain in HV.

Correction of Ankle Varus Deformity using Patient Specific Dome Shaped Osteotomy Guides Designed on Weight Bearing CT

Category:Ankle Arthritis; HindfootIntroduction/Purpose:Dome shaped supramalleolar osteotomies are a well-established treatment option for correcting ankle deformity. However, the procedure remains technically demanding and is limited by a two-dimensional (2-D) radiographic planning of a three-dimensional (3-D) deformity. Therefore, we implemented a weight-bearing CT-scan (WBCT) to plan a 3-D deformity correction using patient specific guides.Methods:A 3-D guided dome shaped supramalleolar osteotomy was performed to correct ankle varus deformity in a cohort of 5 patients with a mean age of 53,8 years (range: 47-58). WBCT images were obtained to generate 3-D models, which enabled a deformity correction using patient specific guides. These technical steps are outlined and associated with a retrospective analysis of the clinical outcome using the EFAS score, Foot and Ankle Outcome Score (FAOS) and Visual Analog Pain scale (VAS).Radiographic assessment was performed using the tibial anterior surface angle (TAS), tibiotalar angle (TTS), talar-tilt angle (TTA), hindfoot angle (HA), tibial lateral surface angle (TLS) and tibial rotation angle (TRA).Results:The mean follow-up was 40,8 months (range 8-65) and all patients showed improvements in the EFAS score, FAOS and VAS (p < 0.05). A 3-month postoperative WBCT confirmed healing of the osteotomy site and radiographic improvement of the TAS, TTS and HA (p<0.05), but the TTA and TRA did not change significantly (p>0.05).Conclusion:Dome shaped supramalleolar osteotomies using 3-D printed guides designed on WBCT, are a valuable option in correcting ankle varus deformity and mitigates the technical drawbacks of free-hand osteotomies.

Weight Bearing CT Analysis of the Transverse Tarsal Joint During Eversion and Inversion

Category:Basic Sciences/Biologics; HindfootIntroduction/Purpose:Current understanding of the kinematics of the transverse tarsal joint continues to evolve. Unfortunately, most prior studies have been in cadavers or under non-physiologic conditions. Weight bearing CT scans may provide more accurate in vivo information about the position of the transverse tarsal joint during eversion and inversion.Methods:Institutional Review Board approval was obtained. Five normal volunteers underwent bilateral weight bearing cone- beam PedCAT scans (CurveBeam LLC, Hatfield, PA) while standing on platforms that positioned both hindfeet in 20o of valgus and then 20o of varus. The CT scans had a field-of-view diameter of 350 mm and a field-of-view height of 200 mm. The scan exposure time was 9 seconds, with a total scan time of 54 seconds. The datasets were reconstructed using filtered back projection with 0.37mm isotropic voxels. The resulting volumes were then segmented, identifying the [x, y, z] coordinates that comprised each bone. Each bone of the hindfoot was segmented on the scan images and the motion between the talus and calcaneus was analyzed. A similar analysis was done for motion between the navicular and cuboid. Two-tailed paired Student's t- tests were used to compare the angle and distance measurements between valgus and varus positions.Results:In the coronal plane, the axis of the talus rotated by 17.0° relative to the axis of the calcaneus as the hindfoot moved from eversion to inversion (p=0.03). The distance between the centers of the talar head and the anterior calcaneus also moved closer to each other by 7.1 mm (p=0.00005). There was no significant change in angle or distance between the navicular and cuboid when moving from eversion to inversion. The angle between the navicular and cuboid axes changed 2.1° (p=0.7), while the distance changed 0.8 mm (p=0.7)Conclusion:Previous work proposed that the transverse tarsal joint locking mechanism occurs from the talonavicular and calcaneocuboid joint axes diverging (less parallel) as the hindfoot inverts. The current weight bearing CT data shows that not only do the talar and calcaneal axes rotate relative to each other during inversion, but the center of the talar head and anterior calcaneus translate to move closer together. Because the navicular and cuboid do not move, transverse tarsal joint locking may occur due to tightening of the joint capsules and ligaments. Further in vivo study is warranted, especially under dynamic weightbearing conditions.

Deep Learning Improves the Accuracy of Weightbearing CT Scan in Detecting Subtle Syndesmotic Instability

Category:Ankle; TraumaIntroduction/Purpose:Weightbearing CT (WBCT) scan provides an ability to compare the ankle joints bilaterally in a 3D manner under physiologic load. According to our recent investigations, 3D volume measurement of the syndesmosis, if measured up to 5cm proximal to the tibial plafond, can detect the instability with an accuracy of 90%, sensitivity of 95.8%, and specificity of 83.3%. However, these values can differ based on the knowledge and experience of the human interpreter. Deep learning, as a subset of machine learning, has shown promising potentials in processing and analyzing images and detecting abnormalities within the images using deep convolutional neural networks (DCNN). Herein, we aimed to assess the accuracy, sensitivity, and specificity of 3D volume WBCT evaluation using DCNN algorithms in patients with subtle syndesmotic instability.Methods:In this study 140 bilateral ankle WBCT scans of patients with subtle syndesmotic instability who were diagnosed intraoperatively were allocated to the patient group. The control group comprised 140 bilateral ankle WBCT images of healthy individuals. We utilized inception V3 model for our DCNN. Data augmentation and transfer learning were used; however, the images were not preprocessed in terms of change in size and resolution. The data were divided as 80:10:10 for training, validation, and test subsets, respectively. The outcome of the study was expressed as sensitivity, specificity, F-score, and the area under the curve (AUC).Results:The performance of our DCNN algorithm showed a sensitivity of 99.41%, specificity of 99.34%, F-score of 99.37%, and 99.99% AUC (Figure 1). The change in loss value of the train data was plateaued after 40 iterations. Axial images were the most appropriate images that were used by the algorithm to detect the instability.Conclusion:In this study we observed that using DCNN in the process of WBCT image interpretation for diagnosis of syndesmotic instability, particularly in subtle cases, makes this modality almost perfect with a very small chance of missing a case. Training a DCNN using a greater number of inputs is still recommended to improve the validity and reliability of this method. Providing a heat map will also help clinicians discover the process of decision-making by these algorithms as DCNNs are sometimes called 'black box'.

Weber C Fractures Treated with ORIF, Syndesmotic Dynamic Fixation and Open Deltoid Repair: Clinical and Radiographic Evaluation after Minimum 12 Months

Category:Trauma; AnkleIntroduction/Purpose:Ankle fractures are among the most common fractures in the body and it can affect not only professional athletes but also lower activity level and sedentary patients. The standard treatment for displaced fractures is open reduction and internal fixation. Even though the management for Weber B and C fractures is well stablished in the literature, deltoid ligament repair is still debatable. Medial ligament instability is a result of deltoid ligament failure and usually leads to valgus deformity of the ankle and severe morbidity over time. The primary objective of this study is to analyze clinically and radiographically, patients with Weber C fractures and deltoid ligament injury who were submitted to fibular fracture and syndesmotic fixation, associated with deltoid ligament repair.Methods:Forty one patients who had Weber C fractures with deltoid ligament lesion from January 2013 to December 2019 had their medical records and X-Rays reviewed by a fully trained foot and ankle surgeon. The patients were between 14 and 69 years old and had their medial clear space wider than 4mm on initial X-Rays (our criteria for deltoid ligament lesion). Patients with Weber A or B, diabetics and with previous surgeries on the ankle were excluded. Patients were submitted to open anatomic reduction and fixation of the fibula, the syndesmosis was fixed with dynamic fixation system and the deltoid was reattached to the tip of the medial malleolus with one suture anchor. Medial Clear Spcace, Tibiofiluar clear space and Tibiofibular overlap were measuresd on weight bearing X-Rays done on the last follow up visit. FAAM sports Subscale17 and VR12 were used to evaluate clinical status of our patients.Results:Forty one patients were analyzed on this series after 22 months on average. The mean age at operation was 37.7 years old. There were 32 males and 9 females. Mental and Physical VR-12 scores went from 56 and 37 pre-operatively to 57 and 50 on their final evaluation. Activity Daily Living and Sports FAAM scores improved from 27 and 7 to 19 and 88 respectively. Post- operative mean medial clear space was 3mm, and mean tibio-fibular clear space was 5mm. The average tibio-fibular overlap percentage was 46%. Patient's overall satisfaction rate was 86.7%.Conclusion:Weber C fractures with Deltoid ligament lesion can be successfully treated with anatomic reduction, syndesmotic fixation (dyanamic systems) and open deltoid repairs. Patients show excellent reduction parameters on weight-bearing X-Rays and good clinical outcomes after a minimum 12 months follow up. Comparative studies with and without deltoid ligament repair should be performed to compare two techniques. Weight-bearing CT scan could be used in future studies for more accurate evaluation of the syndesmotic reduction and medial clear space.

Association of First Metatarsal Pronation with Patient-Reported Outcomes and Recurrence Rates in Hallux Valgus

Category:BunionIntroduction/Purpose:Hallux valgus (HV) is a triplanar deformity of the first metatarsal in which the first metatarsal adducts, dorsiflexes, and pronates with an average increase in pronation between 2° and 8° compared with normal patients (Kimura JBJS, Campbell FAI). Despite these radiographic changes of the first metatarsal in patients with HV, no correlation between postoperative two-dimensional radiographic parameters and patient-reported outcomes has been reported (Thordarson FAI). The purpose of this study was to determine if a postoperative decrease in first metatarsal pronation (1MTPronation) was associated with changes in patient-reported outcomes as measured by the PROMIS physical function, pain interference, and pain intensity domains or recurrence rates in patients with HV who undergo a first tarsometatarsal fusion (modified Lapidus procedure).Methods:This study included thirty-nine consecutive HV patients who underwent a modified Lapidus procedure, had preoperative and >=2-year postoperative PROMIS scores, and had 1MTPronation measured using the previously described triplanar angle of pronation (FAI, in press) on preoperative and at least 5-month postoperative weightbearing CT scans.Multivariable regression analyses were used to investigate differences in the change in PROMIS domains preoperatively and 2-years postoperatively between patients with 'no change/increased 1MTPronation' and 'decreased 1MTPronation.' No differences in preoperative radiographic parameters or patient characteristics found between two groups. A secondary analysis using multivariable regression modeling was performed to determine if patients with a decrease in 1MTPronation between 2°-8° ('moderate pronation change') had greater improvements in PROMIS scores compared with 'minimal pronation change' (<2°) and 'substantial pronation change' (>8°) groups. A log-binomal regression analysis was performed to identify if a decrease in 1MTPronation was associated with recurrence of the HV deformity (postoperative HVA>=20°Results:The decreased 1MTPronation group (n=26) had a statistically significant greater improvement in the PROMIS physical function scale by 7.2 points (95% confidence interval (CI) 2.1-12.3, P=0.007) compared to the no change/increased 1MTPronation group (n=13). There were no statistically significant differences in PROMIS pain interference (P=0.380) or pain intensity (P=0.443) scores between the two groups. The secondary analysis found that patients in the moderate pronation change group (n=15) had significantly better improvements in the PROMIS physical function and pain intensity domains than the minimal pronation change group (n=14) (Table 1). The moderate pronation change group also had greater improvements in the PROMIS pain interference and pain intensity domains than the substantial pronation (n=10) change group (Table 1). Recurrence rates were significantly lower in the decreased 1MTPronation pronation group when compared to the no change/increased 1MTPronation group (11.5% and 46.2%, respectively; risk ratio 0.25, 95% CI 0.07-0.84, P=0.025).Conclusion:In patients undergoing a modified Lapidus procedure for correction of their HV deformity, a postoperative decrease in pronation of the first metatarsal, especially between 2° and 8°, was associated with improvement in PROMIS scores at two- years postoperatively and a lower recurrence rate. These results suggest that the rotational component of the hallux valgus deformity may play an important role in outcomes following surgery, and consequently, surgeons should consider addressing but not overcorrecting the first metatarsal pronation deformity when performing a surgical procedure for the treatment of hallux valgus.

The Association of Crista Volume With Sesamoid Position as Measured From 3D Reconstructions of Weightbearing CT Scans.

Malposition of the sesamoids relative to the first metatarsal head may relate to intersesamoid crista underdevelopment or erosion. Using 3-dimensional models created from weightbearing CT (WBCT) scans, the current work examined crista volume and its relationship to first metatarsal pronation and sesamoid station. Thirty-eight hallux valgus (HV) patients and 10 normal subjects underwent weightbearing or simulated WBCT imaging. The crista was outlined by the inferior articular surface, and a line was drawn to connect the lowest point of each sulcus on either side of the intersesamoidal crista throughout the length of the crista. The volume was calculated. Sesamoid station and first metatarsal pronation were calculated from the 3D reconstructions. The mean crista volumes between HV and normal patients were statistically compared, as were the crista volume and pronation angle between sesamoid stations. The mean crista volume in HV patients was 80.10 ± 35 mm3 and in normal subjects was 150.64 ± 24 mm3, which differed significantly between the 2 groups (P < .001). Mean crista volumes were found to be statistically significantly different between the sesamoid stations (P < .001) with decreasing crista volumes significantly and strongly correlated with increasing sesamoid station (r = -0.80, P < .001). There was no difference in the mean pronation angle between the 4 sesamoid stations (P = .37). The pronation angle was not associated with crista volume (P = .52). HV patients have lower mean crista volume than normal patients. Crista volume is correlated with sesamoid station. Pronation of the first metatarsal was not associated with crista volume. Crista volume may offer an additional determinant for the severity of hallux valgus.

Automatic software-based 3D-angular measurement for Weight-Bearing CT (WBCT) provides different angles than measurement by hand

BackgroundPurpose of this study was to compare automatic software-based angular measurement (AM, Autometrics, Curvebeam, Warrington, PA, USA) with previously validated measurement by hand (MBH) regarding angle values and time spent for the investigator for Weight-Bearing CT (WBCT). MethodsFive-hundred bilateral WBCT scans (PedCAT, Curvebeam, Warrington, PA, USA) were included in the study. Five angles (1st - 2nd intermetatarsal angle, talo-metatarsal 1-angle (TMT) dorsoplantar and lateral projection, hindfoot angle, calcaneal pitch angle) were measured with MBH and AM on the foot/ankle (side with pathology). Angles and time spent of MBH and AM were compared (t-test, homoscedatic). ResultsThe specific pathologies were ankle osteoarthritis/instability, n = 147 (29%); Haglund deformity/Achillodynia, n = 41 (8%); forefoot deformity, n = 108 (22%); Hallux rigidus, n = 37 (7%); flatfoot, n = 35 (7%); cavus foot, n = 10 (2%); osteoarthritis except ankle, n = 82 (16%). The angles differed between MBH and AM (each p < 0.001) except the calcaneal pitch angle (p = 0.05). The time spent for MBH / AM was 44.5 ± 12 s / 1 ± 0 s on average per angle (p < 0.0011). ConclusionsAM provided different angles as MBH and can currently not be considered as validated angle measurement method. The investigator time spent is 97% lower for AM (1 s per angle) than for MBH (44.5 s per angle). Cases with correct angles in combination with almost no time spent showed the real potential of AM. The AM system will have to become reliable (especially in diminishing positive and negative angle values as defined) and valid which has to be proven by planned studies in the future. Level of evidenceLevel III

Pronation on weightbearing radiographs does not correlate with pronation from weightbearing CT scans

IntroductionIn hallux valgus (HV), first metatarsal pronation is increasingly recognized as an important aspect of the deformity. The purpose of this study was to compare pronation in HV patients determined from the shape of the lateral head of the first metatarsal on AP weightbearing radiographs with pronation calculated from weightbearing CT (WBCT) scans. MethodsPatients were included in this study if they had preoperative and 5-month postoperative WBCT scans and corresponding weightbearing AP radiographs of the affected foot. Pronation of the first metatarsal on WBCT scans was measured using a 3D CAD model and the alpha angle and categorized into four groups on radiographs. Association between pronation groups on radiographs and WBCT scans was determined using Spearman correlation coefficients (rs) and by comparing mean WBCT pronation of the first metatarsal between plain radiograph pronation groups. ResultsAgreement between the two observers’ pronation on radiographs was good (k = 0.634) and moderate (k = 0.501), respectively. There was no correlation between radiographic pronation and the 3D CAD model (rs < 0.15). Preoperatively, there was weak correlation between the alpha angle and the radiographic pronation groups (rs = 0.371, P = 0.048) although this relationship did not hold postoperatively (rs = 0.330, P = 0.081). There was no difference in mean pronation calculated on WBCT scans between the plain radiographic groups. ConclusionPronation of the first metatarsal measured on weightbearing AP radiographs had moderate interobserver agreement and was only weakly associated with pronation measured from WBCT scans. These results suggest that first metatarsal pronation measured on weightbearing radiographs is not a substitute for pronation measured on WBCT scans. Level of evidenceIII, retrospective cohort study.

Assessment of Progressive Collapsing Foot Deformity Using Semiautomated 3D Measurements Derived From Weightbearing CT Scans

In progressive collapsing foot deformity (PCFD), hind- and midfoot deformities can be hard to characterize based on weightbearing plain radiography. Semiautomated 3-dimensional (3D) measurements derived from weightbearing computed tomography (WBCT) scans may provide a more accurate deformity assessment. In the present study, automated 3D measurements based on WBCT were used to compare hindfoot alignment of healthy individuals to patients with PCFD. The WBCT scans of 20 patients treated at our institution with either a flexible (N = 10) or rigid (N = 10) PCFD were compared with the WBCT scans of a control group of 30 healthy individuals. Using semiautomated image analysis software, from each set of 3D voxel images, we measured the talar tilt (TT), hindfoot moment arm (HMA), talocalcaneal angle (TCA; axial/lateral), talonavicular coverage (TNC), and talocalcaneal overlap (TCO). The presence of medial facet subluxation as well as sinus tarsi/subfibular impingement was additionally assessed. With the exception of the TCA (axial/lateral), the analyzed measurements differed between healthy individuals and patients with PCFD. The TCA axial correlated with the TNC in patients with PCFD. An increased TCO combined with sinus tarsi impingement raised the probability of predicting a deformity as rigid. Using 3D measurements, in this relatively small cohort of patients, we identified relevant variables associated with a clinical presentation of flexible or rigid PCFD. An increased TCO combined with sinus tarsi impingement raised the probability of predicting a deformity as rigid. Such WBCT-based markers possibly can help the surgeon in decision-making regarding the appropriate surgical strategy (eg, osteotomies vs realignment arthrodesis). However, prospective studies are necessary to confirm the utility of the proposed parameters in the treatment of PCFD. Level III, case-control study.

Association of First Metatarsal Pronation Correction With Patient-Reported Outcomes and Recurrence Rates in Hallux Valgus.

The purpose of this study was to determine if a postoperative decrease in first metatarsal pronation on 3-dimensional imaging was associated with changes in patient-reported outcomes as measured by the Patient-Reported Outcomes Measurement Information System (PROMIS) physical function, pain interference, and pain intensity domains or recurrence rates in patients with hallux valgus (HV) who undergo a first tarsometatarsal fusion (modified Lapidus procedure). Thirty-nine consecutive HV patients who met the inclusion criteria and underwent a modified Lapidus procedure had preoperative and ≥2-year postoperative PROMIS scores and had first metatarsal pronation measured on preoperative and at least 5-month postoperative weightbearing CT scans were included. Multivariable regression analyses were used to investigate differences in the change in PROMIS domains preoperatively and 2 years postoperatively between patients with "no change/increased first metatarsal pronation" and "decreased first metatarsal pronation." A log-binomial regression analysis was performed to identify if a decrease in first metatarsal pronation was associated with recurrence of the HV deformity. The decreased first metatarsal pronation group had a significantly greater improvement in the PROMIS physical function scale by 7.2 points (P = .007) compared with the no change/increased first metatarsal pronation group. Recurrence rates were significantly lower in the decreased first metatarsal pronation group when compared to the no change/increased first metatarsal pronation group (risk ratio 0.25, P = .025). Detailed review of this limited cohort of patients who underwent a modified Lapidus procedure suggests that the rotational component of the HV deformity may play an important role in outcomes and recurrence rates following the modified Lapidus procedure. Level III, retrospective cohort study.

Accuracy of Weightbearing CT Scans for Patient-Specific Instrumentation in Total Ankle Arthroplasty.

Background:Total ankle arthroplasty (TAA) is a popular and viable option for end-stage ankle arthritis. Posttraumatic arthritis is the most common etiology of ankle arthritis, which creates the additional challenge of osseus deformity. Accuracy and reproducibility in placing the implant on the mechanical axis has been shown to be paramount in all joint arthroplasty including total ankle replacement. Patient-specific preoperative navigation is a relatively new technology for TAA, and up until this past year has been based off of nonweightbearing (NWBCT) or simulated weightbearing computed tomography (WBCT). Our institution has created a protocol to use WBCT in the preoperative patient-specific navigation for TAA using the Prophecy system. The purpose of our study was to compare the accuracy and reproducibility of implant alignment and size using WBCT vs prior studies using NWBCT for the Prophecy reports.Methods:All patients from July 2019 through October 2020 who underwent TAA were evaluated. Inclusion criteria consisted of primary TAA using patient-specific preoperative navigation who had postoperative radiographs in the 4-6-week time frame. Prophecy predictions and measurements were then compared to actual implant placement and size.Results:Ten patients met our inclusion criteria of WBCT Prophecy preoperative planning using 2 different implant systems. Preoperative deformities in this cohort were small. The average postoperative coronal alignment was 0.84 degrees, range 0.19 to 2.4 degrees. Average postoperative sagittal plane deformity was 1.9 degrees, range 0.33 to 5.05 degrees. Tibial component size was properly predicted in all patients, talar component in 9 of 10.Conclusion:This initial report supports accuracy and reproducibility in preoperative patient-specific navigation when using WBCT for TAA with these implants. All TAAs were within the intended target of less than 5 degrees varus or valgus.Level of Evidence:Level III, retrospective comparative analysis.

Multiplanar instability of the first tarsometatarsal joint in hallux valgus and hallux rigidus patients: a case-control study.

Hypermobility of the first ray has been considered associated with various forefoot diseases including hallux valgus (HV) and hallux rigidus (HR). Weightbearing CT scan can be a reliable method for analysis of the first tarsometatarsal (TMT) joint in axial, sagittal, and coronal planes. Our objective was to comparatively investigate signs of instability of the first TMT joint on weightbearing CT between three groups (control, HV, and HR). In this single-centre, retrospective, case-control study, 27 HV patients (30 feet; mean age 54.2years), 26 HR patients (30 feet; mean age 56.6years), and 30 controls (30 feet; mean age; 43years) were enrolled. Measurements of signs of instability were performed in multiplanes including first TMT angle, dorsal translation of the first metatarsal (M1) at the first TMT joint, plantar distance between the medial cuneiform (C1) and M1 in sagittal plane, hallux valgus angle (HVA), intermetatarsal angle (IMA) in axial plane, rotational profiles of C1 and M1 in coronal plane. Analysis of variance (ANOVA) test and chi-square test were performed to compare each parameter between the three groups. Interobserver reliabilities were assessed using interclass correlation coefficients (ICCs). The HV group had significantly increased first TMT angle (0.23° in controls, 1.15° in HV, 0.19° in HR, p < 0.001), HVA (7.52°, 33.50°, 11.21°, p < 0.001), IMA (9.46°, 16.98°, 11.87°, p < 0.001), C1-M1 angle (22.44°, 29.46°, 23.74°, p < 0.001), and rotational profile of the distal M1 (7.06°, 17.88°, 9.85°, p < 0.001) compared with the control and HR groups. Dorsal translation of M1 (23% in controls, 63% in HV, 70% in HR, p < 0.001) was frequently found in the HV and HR groups with significantly increased plantar distance (0.37mm, 1.14mm, 1.46mm, p < 0.001) compared with controls. Multiplanar instability of the first TMT joint was confirmed using weightbearing CT in HV and HR groups compared with controls. HV group demonstrated instability mainly in sagittal and axial planes; HR group had sagittal instability predominantly. Our measurement of rotational instability at the first TMT joint was not able to detect differences between groups. A surgical correction of the instability at the first TMT joint can be an option to address HV and HR. First ray hypermobility at the first TMT joint is an important consideration when addressing HV and HR, a surgical correction of the instability at the first TMT joint should be taken in consideration as an option.