Weightbearing CT Scans Research Articles

Different Positions of Weightbearing CT Images Can Influence the Hindfoot Alignment Evaluation Using 2-Dimensional Methodology.

Three-dimensional weightbearing CT (WBCT) has been widely used to assess foot and ankle alignment. However, most current measurement methods are based on 2-dimensional concepts-distance, long axis, angulation, etc-and are sensitive to changes in orientation of the WBCT images. This study demonstrated how changes in positioning of the image can significantly influence the evaluation of hindfoot alignment. WBCT scans of 10 feet without deformities were used. In the horizontal view, the long axis of the foot image was aligned to a neutral position and then rotated 5, 10, 15, and 20 degrees both internally and externally to simulate malposition. The Calcaneal Moment Arm (CMA) was measured by 2 investigators independently in the above positions. An intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliabilities. The correlation between the CMA and the rotation angle of the foot images was analyzed using linear regression. The CMA measurements demonstrated that internal rotation of the image changed the neutral hindfoot into valgus, whereas external rotation led to varus. A 1-degree internal or external rotation of the image correlated with 0.48 (±0.03) mm increase or decrease in the modified WBCT-CMA value (P < .0001, R2 = 0.6406). This study demonstrated that although 3D WBCT provides the ability to observe the foot from different perspectives, current alignment evaluation tools are limited to 2 dimensions. Therefore, positioning the WBCT images in a consistent orientation is important to generate correct data.

Preoperative planning of total ankle prosthesis – What are we aiming at?

IntroductionAnkle osteoarthritis poses significant challenges, affecting patients’ quality of life and often necessitating surgical intervention. Total ankle replacement (TAR) has emerged as an effective treatment, in patients with post-traumatic arthritis. Precise preoperative planning is crucial for achieving optimal outcomes in TAR procedures. This article explores the use of advanced imaging techniques, virtual modeling, and surgical strategies in preoperative planning for TAR. MethodsThe preoperative planning process involves thorough patient assessment, including clinical examination and imaging studies such as Weight Bearing CT scans (WBCT) and MRI. Classification systems like the Canadian Orthopedic Foot & Ankle Society (COFAS) classification help guide treatment decisions and staging of procedures. Virtual foot/ankle models derived from WBCT scans enable accurate assessment of deformities and facilitate precise implant positioning. DiscussionOptimal TAR outcomes rely on restoring normal ankle anatomy and function while addressing associated deformities and pathology. Precise alignment, joint congruency, and rotational positioning of implant components are Important considerations. Virtual planning allows for simulation of implant placement and axis correction, aiding surgical decision-making and predicting outcomes. However, it has limitations in predicting soft tissue effects and final implant size. ConclusionPreoperative planning plays a important role in TAR procedures, understanding optimal implant placement. Advanced imaging modalities, classification systems, and virtual modeling techniques enhance surgical precision. Continued refinement of preoperative planning strategies is essential for further advancing TAR outcomes and patient satisfaction.10.1016/j.fuspru.2024.07.001

Morphological changes in flatfoot: a 3D analysis using weight-bearing CT scans

BackgroundFlatfoot is a condition resulting from complex three-dimensional (3D) morphological changes. Most Previous studies have been constrained by using two-dimensional radiographs and non-weight-bearing conditions. The deformity in flatfoot is associated with the 3D morphology of the bone. These morphological changes affect the force line conduction of the hindfoot/midfoot/forefoot, leading to further morphological alterations. Given that a two-dimensional plane axis overlooks the 3D structural information, it is essential to measure the 3D model of the entire foot in conjunction with the definition under the standing position. This study aims to analyze the morphological changes in flatfoot using 3D measurements from weight-bearing CT (WBCT).MethodIn this retrospective comparative our CT database was searched between 4–2021 and 3–2022. Following inclusion criteria were used: Patients were required to exhibit clinical symptoms suggestive of flatfoot, including painful swelling of the medial plantar area or abnormal gait, corroborated by clinical examination and confirmatory radiological findings on CT or MRI. Healthy participants were required to be free of any foot diseases or conditions affecting lower limb movement. After applying the exclusion criteria (Flatfoot with other foot diseases), CT scans (mean age = 20.9375, SD = 16.1) confirmed eligible for further analysis. The distance, angle in sagittal/transverse/coronal planes, and volume of the two groups were compared on reconstructed 3D models using the t-test. Logistic regression was used to identify flatfoot risk factors, which were then analyzed using receiver operating characteristic curves and nomogram.ResultThe flatfoot group exhibited significantly lower values for calcaneofibular distance (p = 0.001), sagittal and transverse calcaneal inclination angle (p < 0.001), medial column height (p < 0.001), sagittal talonavicular coverage angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.015) Hibb angle. In contrast, the sagittal lateral talocalcaneal angle (p = 0.013), sagittal (p < 0.001) and transverse (p = 0.004) talocalcaneal angle, transverse talonavicular coverage angle (p < 0.001), coronal Hibb angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.001) Meary’s angle were significantly higher in the flatfoot group. The sagittal Hibb angle (B = − 0.379, OR = 0.684) and medial column height (B = − 0.990, OR = 0.372) were identified as significant risk factors for acquiring a flatfoot.ConclusionThe findings validate the 3D spatial position alterations in flatfoot. These include the abduction of the forefoot and prolapse of the first metatarsal proximal, the arch collapsed, subluxation of the talonavicular joint in the midfoot, adduction and valgus of the calcaneus, adduction and plantar ward movement of the talus in the hindfoot, along with the first metatarsal’s abduction and dorsiflexion in the forefoot.

IMPACTION BONE GRAFTING OF LARGE DEFECTS IN ANKLE AND HINDFOOT FUSIONS

BackgroundAnkle and hindfoot fusion in the presence of large bony defects represents a challenging problem. Treatment options include acute shortening and fusion or void filling with metal cages or structural allograft, which both have historically low union rates. Impaction grafting is an alternative option.MethodsA 2 centre retrospective review of consecutive series of 32 patients undergoing hindfoot fusions with impaction bone grafting of morselised femoral head allograft to fill large bony void defects was performed. Union was assessed clinically and with either plain radiography or weightbearing CT scanning. Indications included failed total ankle replacement (24 patients), talar osteonecrosis (6 patients) and fracture non-union (2 patients). Mean depth of the defect was 29 ±10.7 mm and mean maximal cross-sectional area was 15.9 ±5.8 cm2. Tibiotalocalcaneal (TTC) arthrodesis was performed in 24 patients, ankle arthrodesis in 7 patients and triple arthrodesis in 1 patient.ResultsMean age was 57 years (19–76 years). Mean follow-up of 22.8 ±8.3 months. 22% were smokers. There were 4 tibiotalar non-unions (12.5%), two of which were symptomatic. 10 TTC arthrodesis patients united at the tibiotalar joint but not at the subtalar joint (31.3%), but only two of these were symptomatic. The combined symptomatic non-union rate was 12.5%. Mean time to union was 9.6 ±5.9 months. One subtalar non-union patient underwent re-operation at 78 months post-operatively after failure of metalwork. Two (13%) patients developed a stress fracture above the metalwork that healed with non-operative measures. There was no bone graft collapse with all patients maintaining bone length.ConclusionImpaction of morselised femoral head allograft can be used to fill large bony voids around the ankle and hindfoot when undertaking arthrodesis, with rapid graft incorporation and no graft collapse despite early loading. This technique offers satisfactory union outcomes without the need for shortening or synthetic cages.

3D AUTOMATED VERSUS MANUAL ASSESSMENT OF ALIGNMENT IN NORMAL AND CAVUS FEET USING WEIGHT-BEARING CT SCANS: DOES IT DIFFER?

BackgroundThe complex deformities in cavovarus feet may be difficult to assess and understand. Weight-bearing CT (WBCT) is increasingly used to evaluate complex deformities. However, the bone axes may be difficult to calculate in the setting of severe deformity. Computer-assisted 3D-axis calculation is a novel approach that may allow for more accurate assessment of foot alignment / deformity. The aim of this study was to assess differences in measurements done manually on 2D slices of WBCT versus 3D computer models in normal and cavus feet.MethodsWe retrospectively analyzed WBCT scans from 16 normal and 16 cavus feet in patients with Charcot-Marie Tooth. Eight measurements were assessed: Talus-1st metatarsal angle (axial plane), Forefoot arch angle (coronal plane), and Meary's angle, calcaneal pitch, cuneiform to floor, cuneiform to skin, navicular to floor and navicular to skin distance (sagittal plane). 2D measurements were performed manually and 3D measurements were performed using specialised software (BoneLogic, DISIOR).ResultsThere was no significant difference in the measured variables (2D manual versus 3D automated) in normal feet. In the cavus group, 3D assessment calculated increased values for the sagittal angles: Meary's 7.3 degrees greater (p = 0.004), calcaneal pitch 2.4 degrees greater (p = 0.011)), and lower values for the axial talus-1st MT angle, 10.6 degrees less (p = 0.001).ConclusionThere were no significant differences in the normal group. This suggests 3D automated techniques can reliably assess the alignment of bony axes. However, the 3D axis calculations suggest there may be greater sagittal and lesser axial deformity in cavus feet than measured by 2D techniques. This discrepancy may be on account of the rotation seen in cavovarus feet, which may not be readily assessed manually. 3D automated measurements may therefore have a role in better assessing and classifying the cavus foot which may ultimately help inform treatment algorithms.

Automation improves the efficiency of weightbearing CT scan 3D volumetric assessments of the syndesmosis

BackgroundWeight-bearing CT (WBCT) 3D volumetric measurement has shown promising accuracy for the diagnosis of syndesmotic instability. However, these measurements are rather complex and time-consuming, rendering them a clinically unfavorable option. We hypothesized that automatized measurements would be more accurate and time-efficient than manual ones. MethodsThirty cases of intraoperatively confirmed syndesmotic instability along with thirty individuals with no injuries to the ankle joint were recruited as cases and controls, retrospectively. Two observers conducted the manual volumetric measurements two times, at a one-week interval. An automated algorithm for 3D WBCT measurements was developed to conduct the measurements on the axial images. The time spent on each method was recorded. Mann-Whitney U test was used to compare the values between human raters and computers. Inter- and intra-class reliability were calculated. ResultsThe intra-class correlation coefficient was found to be “excellent” for the automated measurements (0.97) and “good” for the observers (0.75). Similarly, the Cronbach’s alpha was shown to be higher for the computer (0.88) than the observers (0.60 and 0.62). The mean time spent on the measurements was different between human raters and the computer-assisted method (p < 0.001). ConclusionAutomated volumetric assessment of syndesmosis seems to be a faster and more reliable option than the manual one. We suggest future larger-scale prospective studies conducted under actual clinical circumstances for more definitive conclusions. Level of evidenceRetrospective case-control study - Level 3

Preoperative Degenerative Changes at the Medial Sesamoid-Metatarsal Joint Is Associated with Postoperative Patient-Reported Outcomes in Hallux Valgus

Introduction/Purpose: While hallux valgus (HV) is understood to be a triplanar deformity of the first metatarsal, less is known about the contribution of the sesamoid-metatarsal joint (SMJ) to pain and function. Osteoarthritis of the SMJ is frequently present in HV feet, with an incidence rate ranging from 32% to 81%. Following surgical correction, approximately 10% of HV patients remain dissatisfied, but factors affecting postoperative outcomes are poorly understood. The primary aim of our study was to describe the relationship between degenerative changes at the SMJ as measured on weightbearing CT (WBCT) scans and 1-year patient-reported outcome scores following a modified Lapidus procedure for correction of HV. We hypothesized that decreased joint space at the SMJ would affect postoperative patient-reported outcomes. Methods: This study included 48 consecutive patients who underwent a modified Lapidus procedure for HV, had preoperative and at least 5-month postoperative WBCT scans, and had preoperative PROMIS scores and at least 1-year postoperative PROMIS Physical Function (PF), Pain Interference, and Pain Intensity scores. For each patient, the first metatarsal and sesamoids on pre- and postoperative WBCT scans were segmented using Disior Bonelogic software and uploaded to Geomagic Design X to perform distancing mapping. The minimum and average distances between the first metatarsal head and medial sesamoid (medial-SMJ) for each patient pre- and postoperatively were calculated. Sesamoid subluxation was measured on WBCT scans using the grading system from 0 to 3 (Yildirim et al.). A simple linear regression model was used to investigate the correlations between minimum preoperative and postoperative medial-SMJ distances and 1-year postoperative PROMIS scores in patients with postoperative reduction of the sesamoids (grade 0). Results: Preoperatively, the mean minimum and average medial-SMJ distances were 0.76 ± 0.37 mm and 1.54 ± 0.33 mm, respectively. Postoperatively, the mean minimum and average medial-SMJ distances were 1.08 ± 0.25 mm and 1.73 ± 0.24 mm, respectively. Thirty-five of 48 patients had a complete reduction of the sesamoids. Lower preoperative minimum distances at the medial-SMJ were significantly correlated with worse 1-year PROMIS PF scores (r=0.405, P=0.016) (Figure 1). Similarly, lower preoperative minimum distances at the medial-SMJ were significantly correlated with worse 1-year PROMIS Pain Intensity scores (r=-0.350, P=0.039) but did not reach significance for 1-year PROMIS Pain Interference scores (r=-0.286, P=0.095). The postoperative minimum medial-SMJ distance was not correlated with 1-year PROMIS PF, Pain Interference, and Pain Intensity scores. Conclusion: In HV patients undergoing a modified Lapidus procedure with postoperatively reduced sesamoids, decreased joint space at the medial sesamoid-metatarsal head articulation was associated with worse 1-year postoperative function as measured by PROMIS PF scores and worse 1-year postoperative pain as measured by PROMIS Pain Intensity scores. In contrast, postoperative degenerative changes at the SMJ were not found to be associated with patient-reported outcomes. Our results suggest that pre-existing SMJ arthritic changes may affect postoperative outcomes and may be a source of dissatisfaction following HV surgery despite appropriate correction of the deformity. Figure 1. Preoperative medial sesamoid to the first metatarsal head minimum distance relative to 1-year PROMIS Physical Function, Pain Intensity, and Pain Interference scores. A simple linear regression demonstrates a significant association between preoperative medial sesamoid –metatarsal head minimum joint distance and 1-year PROMIS Physical Function (r=0.405, P=0.016) and Pain Intensity (r=‒0.305, P=0.039) scores.

Automatic software-based 3D-angular measurement for weight-bearing CT (WBCT) is valid

BackgroundThe purpose of this study was to compare automatic software-based angular measurement (AM) with validated measurement by hand (MBH) regarding angle values and time spent for Weight-Bearing CT (WBCT) generated datasets. MethodsFive-hundred WBCT scans from different pathologies were included in the study. 1st - 2nd intermetatarsal angle, talo-1st metatarsal angle dorsoplantar and lateral, hindfoot angle, calcaneal pitch angle were measured and compared between MBH and AM. ResultsThe 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 did not differ between MBH and AM (each p > 0.36). The time spent for MBH / AM was 44.5 / 1 s on average per angle (p < .001). ConclusionsAM provided angles which were not different from validated MBH and can be considered as a validated angle measurement method. The time spent was 97% lower for AM than for MBH. Levels of evidenceLevel III

Talar neck rotation angle in adults with clubfoot deformity: Observed values and intra- and inter-observer reliability using weightbearing CT

IntroductionAdults presenting with symptomatic clubfoot represent a challenging cohort of patients. An appreciation of the location and degree of deformities is essential for management. Talar anatomy is often abnormal with varus within the talar neck, however, there are few reproducible methods which quantify talar neck deformity in adults. We describe a technique of assessing talar neck deformity, and report on observed values and intra- / inter-observer reliability. MethodsThis was a single-centre, retrospective study including 96 feet from 56 adult patients with clubfeet (82 feet had clubfoot deformity, 14 were normal). Mean age was 34.3 ± 16.9 years and 31 (55.3%) were male. Weight-bearing CT scans captured as part of routine clinical care were analysed. Image reformats were oriented parallel to the long axis of the talus in the sagittal plane. In the corresponding axial plane two lines were drawn (on separate slices): 1) a line perpendicular to the intermalleolar axis, 2) a line connecting the midpoints of the talar head and narrowest part of the talar neck. The talar neck rotation angle (TNR angle) was the angle formed between these lines. Intraclass correlation coefficients (ICC) were performed for intra- and inter-observer reliability. ResultsMean TNR angle in clubfeet was 27.6 ± 12.2 degrees (95%CI = 25.0 to 30.2 degrees). Mean TNR angle in normal feet was 18.7 ± 5.1 degrees (95%CI = 16.0 to 21.4 degrees) (p < 0.001). The ICC for clubfeet was 0.944 (95%CI = 0.913 to 0.964) for intra-observer agreement, and 0.896 (95%CI = 0.837 to 0.932) for inter-observer agreement. ConclusionThis measurement technique demonstrated excellent intra- and inter-observer agreement. It also demonstrated that compared to normal feet, clubfeet had about 9 degrees of increased varus angulation of the talar neck. This technique and data may be used for future research into clubfoot deformity and in planning treatment. Level of clinical evidence3

The use of deep learning enables high diagnostic accuracy in detecting syndesmotic instability on weight-bearing CT scanning.

Delayed diagnosis of syndesmosis instability can lead to significant morbidity and accelerated arthritic change in the ankle joint. Weight-bearing computed tomography (WBCT) has shown promising potential for early and reliable detection of isolated syndesmotic instability using 3D volumetric measurements. While these measurements have been reported to be highly accurate, they are also experience-dependent, time-consuming, and need a particular 3D measurement software tool that leads the clinicians to still show more interest in the conventional diagnostic methods for syndesmotic instability. The purpose of this study was to increase accuracy, accelerate analysis time, and reduce interobserver bias by automating 3D volume assessment of syndesmosis anatomy using WBCT scans. A retrospective study was conducted using previously collected WBCT scans of patients with unilateral syndesmotic instability. One-hundred and forty-four bilateral ankle WBCT scans were evaluated (48 unstable, 96 control). We developed three deep learning models for analyzing WBCT scans to recognize syndesmosis instability. These three models included two state-of-the-art models (Model 1-3D Convolutional Neural Network [CNN], and Model 2-CNN with long short-term memory [LSTM]), and a new model (Model 3-differential CNN LSTM) that we introduced in this study. Model 1 failed to analyze the WBCT scans (F1 score = 0). Model 2 only misclassified two cases (F1 score = 0.80). Model 3 outperformed Model 2 and achieved a nearly perfect performance, misclassifying only one case (F1 score = 0.91) in the control group as unstable while being faster than Model 2. In this study, a deep learning model for 3D WBCT syndesmosis assessment was developed that achieved very high accuracy and accelerated analytics. This deep learning model shows promise for use by clinicians to improve diagnostic accuracy, reduce measurement bias, and save both time and expenditure for the healthcare system. II.

Association between Postoperative Medial: Middle Intercuneiform Joint Gapping and Recurrence Rates in Hallux Valgus

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) is a triplanar deformity of the first metatarsal, which may extend beyond the first ray. Compared with normal feet, previous studies have found that HV patients have an increase in hypermobility of the joints along the medial column and at the medial – middle (MM) intercuneiform joint. Despite increased instability at the MM intercuneiform joint, no study has investigated its clinical significance. The primary purpose of this study was to determine if postoperative widening of the MM intercuneiform joint was associated with recurrence in HV patients who undergo a first tarsometatarsal fusion (modified Lapidus procedure). A secondary purpose was to investigate whether other HV imaging parameters were associated with a widening of the MM intercuneiform joint. Methods: This study included 52 consecutive HV patients who underwent a modified Lapidus procedure and had preoperative and at least 5-month postoperative weightbearing CT (WBCT) scans. Preoperative and postoperative measurements of HV deformity, including the intermetatarsal angle and hallux valgus angle (HVA) on plain radiographs and triplanar pronation angle and sesamoid station from WBCTs, were performed as previously described. MM intercuneiform distance was measured on the coronal multiplanar reconstructed WBCT scans after reorienting the axial and sagittal planes such that the coronal cuts were orthogonal to the intercuneiform joint (Figure 1A). Recurrence of the HV deformity was defined as a postoperative HVA ≥ 20°. Paired t-tests were used to compare preoperative and postoperative imaging parameters, and Mann-Whitney U tests were used to compare measurements between patients with and without HV recurrence. Pearson correlation coefficients were used to explore associations between preoperative and postoperative measurements and the change in MM intercuneiform distance. Results: Nine of 52 patients (17.3%) had recurrence of their HV deformity. For the entire cohort, the mean preoperative and postoperative MM intercuneiform distances were 0.73 mm (standard deviation (SD) 0.3) and 1.08 mm (SD 0.5), respectively. In patients with and without HV recurrence, the mean widening at the MM intercuneiform joint was 0.69 mm (95% confidence interval (CI) 0.52-0.86) and 0.27 mm (95% CI 0.17-0.38, P&lt; 0.001), respectively. Patients with recurrence had significantly greater widening of the MM intercuneiform joint than patients without recurrence (P=0.001, Figure 1B and Table 1). While no preoperative imaging parameters were associated with a change in the MM intercuneiform distance, increasing postoperative sesamoid position (r=0.32, P=0.022) and HVA (r=0.28, P=0.046) were correlated with a greater change MM intercuneiform joint gapping. Conclusion: In patients undergoing a modified Lapidus procedure for correction of their HV deformity, postoperative widening of the MM intercuneiform joint was associated with recurrence of the HV deformity. As understanding of the HV deformity continues to evolve, our study suggests that there is a complex interplay between deformity at the hallux metatarsophalangeal (MP) joint, reduction of the metatarsosesamoid joint complex, and the instability at the tarsometatarsal and intercuneiform joints. This may guide surgical correction as surgeons may need to address both intercuneiform instability and correction at the hallux MP joint in order to decrease HV recurrence rates.

Three-Dimensional Assessment to Hallux Valgus Correction Using Lapicotton Technique

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: The first-ray and the medial column play a crucial role in preserving the tripod of the foot. Changes to structural properties of the first-ray, along with collapse of the medial-longitudinal-arch, have been associated with hallux valgus (HV). Thus, restoring the first-ray plays an important role when correcting the mechanical function of the foot tripod in the setting of HV combined with medial-longitudinal-arch collapse. The LapiCotton technique combines the mechanical advantages of Cotton osteotomy and modified Lapidus procedures by maintaining the length of the first-ray and preserving the medial- longitudinal-arch by plantar inclination of the distal part of first-ray. The aim of this study was to evaluate the effectiveness of the LapiCotton procedure in correcting selected radiographic parameters in patients with combined VH with medial-longitudinal arch collapse. Methods: Preoperative and postoperative Weight Bearing CT (WBCT) scans were obtained from HV patients who underwent unilateral LapiCotton procedure. Postoperative scans were obtained roughly three months after the date of surgery. Semi- automatic measurements were applied to 22 WBCT images across a total of 11 patients enrolled into the study using the Disior® Bonelogic® Software. Measurements of the hallux valgus angle (HVA), meary sagittal measurement, and intermetatarsal angles were taken from preoperative and postoperative scans. These scans were then compared using intraclass correlation coefficients and paired t-tests to evaluate the efficacy of the Lapicotton technique in treating HV with P-valus &lt; 0.05 being significant. Results: HVA was found to be significantly larger (p=.026) in the preoperational group (Mdn = 27.52) than the postoperational group (Mdn = 20). In addition, the Meary sagittal measurement was found to be significantly different between groups (p=.033), with a larger value seen in the preoperational group (Mdn = -14.28) compared to the post-operational group (Mdn = -11.15). It was also observed that the IMA was significantly larger (p=.003) in the preoperative group (Mdn = 15.68) compared to the postoperative group (Mdn = 11.26). The sesamoid rotation was found to be higher in the preoperative group (Mdn = -17.71) than the post operative group (Mdn = -24.98), however, these values were not significantly different from one another (p=.203). Conclusion: The LapiCotton procedure proved to be effective in correcting radiographic parameters in patients with HV combined with collapse of the medial longitudinal arch. Reliable correction of HV, along with correction of medial longitudinal arch collapse, was quantified based on semi-automated WBCT measurements of HVA, IMA and Meary angle. LapiCotton produced significantly different measurements for both HVA and IMA postoperatively, providing evidence that the LapiCotton procedure can successfully correct medial longitudinal arch collapse in patients with HV, as well as radiographically reduce the severity of the deformity.

Measurements and Protocols Used for Weight-Bearing Cone-Beam CT Scans for Evaluating the Alignment of the Foot and Ankle: A Systematic Literature Review

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Weight bearing CT has been widely used recently to provide detailed 3D information of the foot and ankle. Orthopedic surgeons have been exposed to this new technology, but do not have the equivalent tools to use to explore it. A lot of metrics were directly borrowed from plain radiographic imaging, while some new parameters were developed using traditional axes and angular concepts but on only one specific WBCT view out of hundreds of scans. Some metrics used similar measurement concepts, but on 3D reconstructed bones, while a few new parameters were introduced based on semi 3D and 3D thinking. Small sample sizes, obscure inclusion/exclusion criteria, and skewed validation methods are noted, and a thorough review of WBCT-based measurements used in foot and ankle is warranted. Methods: A literature search was conducted in two databases: PubMed (MEDLINE) and EMBASE (Elsevier). The main search terms and logics were: ((foot) OR (ankle) OR (hindfoot) OR (midfoot) OR (forefoot)) AND ((WBCT) OR (Weightbearing CT) OR (Cone beam CT scan) OR (PedCAT)). A longer string of key words was utilized to further narrow down the results to WBCT imaging associated with foot and ankle pathologies. The terms were expanded using the MeSH and Emtree expansion features of PubMed and EMBASE, respectively. All articles were reviewed by two independent senior foot and ankle surgeons based on pre-designed exclusion criteria. Off-topic articles were removed, and remaining articles were categorized based on measurement techniques. All articles were managed using Zotero. (Figure 1) Results: A total of 216 articles were selected for retrieval and further organized by measurement techniques. Seven groups were set by the type of the methodology used. Among them, 123 studies utilized traditional 2D measurement parameters (eg, hindfoot moment arm, Meary’s angle, talonavicular uncoverage, hallux valgus angle, etc.), 8 introduced new parameters but based on 2D axial/angular concepts (eg, middle facet subluxation percentage and angle), 22 used semi-automated 3D measurement techniques (3D segmentation + 2D axial and angular methods), 19 using semi-3D measurement techniques (Foot and Ankle Offset), 29 measured real 3D parameters (volume evaluation in the syndesmosis and Lisfranc joints, distance mapping), 3 morphological studies used 3D segmentation and sphere fitting. The advantages and disadvantages of each type of measurement were carefully examined and explored. Conclusion: 3D imaging measurements with WBCT appear to be highly variegated. Axial and angular measurements do not apply well to irregular bones and there is a low reproducibility in 3D scenarios. Although inter- and intraobserver reproducibility scores have been reported in multiple studies, they were only part of the validation system that should be done. A high correlation between parameters such as 2D and 3D hindfoot angles has been reported, but debate remains as to whether one method of measurement is more accurate than the other. Furthermore, variations in analytical methods warrant a more uniformly defined coordinate or anatomical system.

Three-Dimensional Distance Map Comparisons between Asymptomatic and Symptomatic Progressive Collapsing Foot Deformity (PCFD)

Category: Hindfoot Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a complex three-dimensional foot deformity that is characterized, in part, by peritalar subluxation (PTS). The subtalar joint has been analyzed in PCFD using distance mapping as a measure of subfibular impingement (Figure 1). However, the progression of PCFD from healthy to asymptomatic to symptomatic and painful, specifically within the subtalar joint, is largely unknown. Therefore, investigating asymptomatic PCFD may offer clinical insight into both the pathology of PCFD within the subtalar joint and how the disease progresses. The objective of this study was to use a three-dimensional distance mapping algorithm of the subtalar joint for asymptomatic PCFD patients to describe and compare this stage of the deformity with a previously described cohort of symptomatic PCFD patients and healthy controls. Methods: In this prospective comparative study, patients with asymptomatic flatfeet were recruited to undergo a weight-bearing CT (WBCT) scan. This cohort (20 feet, 8 male, 12 female) was compared to a previously described cohort of both control (n=10, 4 male, 6 female) and symptomatic PCFD (n=20, 8 male, 12 female). Using a commercially available software package (Disior Bonelogic), models of the talus and calcaneus were created and analyzed. Distance mapping was then used to measure the distance along the normal direction of vectors projected from the calcaneal subchondral surface to the opposing talar surface. In this manner, the subtalar joint was objectively measured across the entire peritalar surface, including articular and nonarticular regions (Figure 1). Mean distances over the described articulations of the subtalar joint were compared using an analysis of variance (ANOVA) test to compare each parameter between the three groups. Results: Regarding mean distance values, the asymptomatic group was significantly higher than symptomatic measures in 10/13 articular surfaces and 3/4 sinus tarsi regions. Asymptomatic distances were also significantly greater than control measures in 11/13 articular surfaces (Table 1, Table 2) but were smaller and without significance in the sinus tarsi region. (Table 3). When looking at the sinus tarsi as a whole, asymptomatic distances (mean 3.21mm) were greater than both control (mean 2.73mm, p=0.01,) and symptomatic distances (mean 2.63, p=0.002) (Table 1). More specifically, asymptomatic distances were different than both symptomatic and control distances in the anteromedial, posteromedial and posterolateral regions of the sinus tarsi (Table 3). Conclusion: To our knowledge, this is the first study to examine the asymptomatic flatfoot within the subtalar joint. Asymptomatic distances were found to be largely greater than both symptomatic and control distances. This suggests that the bones are unstable and moving in patients who have flatfeet but no symptoms. When PTS, in an unstable asymptomatic foot, produces sinus tarsi impingement, that may be the trigger to further collapse and subsequent pain. Our data supports the idea that asymptomatic flatfoot should be considered a risk for progression to PCFD and represents a step toward finding predictors for development painful flatfoot.

Comparing Symptomatic and Asymptomatic Flatfeet Using Known Markers of Progressive Collapsing Foot Deformity (PCFD): A Case Control Study

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Flattening of the longitudinal arch of the foot (Flatfoot) can represent a normal spectrum of foot morphology and alignment. The issue comes when the foot is collapsing progressively, what is now termed Progressive Collapsing Foot Deformity (PCFD). Literature on asymptomatic flatfoot is scarce since asymptomatic patients do not seek medical attention. Alignment differences between asymptomatic flatfoot and PCFD have not been established and might represent a key-step in understanding predictors of PCFD. The objective of this prospective study was to compare established PCFD measures in a cohort of asymptomatic flatfoot, PCFD patients and healthy controls. We hypothesized that asymptomatic flatfeet alignment would differ from both symptomatic PCFD patients and healthy controls. Methods: In this prospective comparative study, patients with asymptomatic flatfeet were recruited to undergo a weight-bearing CT (WBCT) scan. This cohort (22 feet, 10 males, 12 females) was compared to two other prospective cohorts (22 symptomatic PCFD and 22 healthy controls). Along with demographic data, PCFD measurements performed include Foot and Ankle Offset (FAO), Forefoot Arch Angle (FAA), Middle Facet Uncoverage, and the Transverse Arch Plantar (TAP) angle. Normality of variables was assessed using the Shapiro-Wilk test. Chi-squared or analysis of variance (ANOVA) test was performed to compare each parameter between the three groups. A post-hoc Bonferroni test was then performed to assess significance between each group pairing. P-values of &gt;0.05 were considered significant. Results: All three groups were comparable on BMI (p=0.10), Age (p=0.75) and Gender (p=0.78). All measurements taken differed significantly between the symptomatic PCFD and healthy controls (Table 1). FAO was significantly different between controls vs asymptomatic (p &lt; 0.001) and asymptomatic vs symptomatic (p &lt; 0.001). FAA was also significantly different between asymptomatic and both symptomatic (p=0.001) and control groups (p=0.001). Middle facet uncoverage differed between the asymptomatic and control group (p=0.001) but the asymptomatic and symptomatic group were similar (p=0.106). While the TAP angle was significantly different between asymptotic and symptomatic groups (p=0.013), the asymptomatic and control groups failed to reach significance (p=0.061) (Table 1). On average, deformity measurements for asymptomatic flatfeet were in between the values for healthy controls and symptomatic PCFD (Figures 1-3). Conclusion: To our knowledge this is the first prospective study to compare healthy controls, asymptomatic flatfoot and symptomatic PCFD patients. We observed that asymptomatic flatfoot patients usually had measurements of PCFD that would fall in between normal alignment asymptomatic controls and symptomatic PCFD patients. Further, the asymptomatic group differed significantly from both other groups on every measure but two. Our data supports the idea that asymptomatic flatfoot should be considered a risk factor for Progressive Collapsing Foot Deformity. Our data can hopefully shine light in finding predictive markers for the development of PCFD.

Weight-bearing CT Scan Analysis in Hallux Valgus Surgery: Comparison between Open (Scarf) and Minimally Invasive (MIBA) Techniques

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) is one of the most prevalent foot deformities. Coronal metatarsal rotation (pronation) has been recognized as a key element in HV deformity and an important prognostic factor for recurrence. With the advent of weight-bearing CT (WBCT), accurate pronation measurement has improved. The Minimally Invasive Bosh Akin (MIBA) surgery has proven to be effective in treating HV deformity. Literature comparing MIBA radiological correction with traditional open techniques (scarf osteotomy) is lacking. Purpose: To compare the transverse and coronal plane deformity correction by WBCT in HV patients treated with open vs MIS technique. Methods: We retrospectively analyzed HV deformity in patients who underwent Scarf and MIBA surgery with preoperative and at least 3 months postoperative WBCT for comparison. Intermetatarsal angle (IMA), hallux valgus angle (HVA), and alpha angle (AA) for first metatarsal pronation was measured by 2 different observers. Pre and postoperative measurement changes were established by T-test for related samples. the p-value for statistical significance was set at &lt; 0.05. Results: 40 feet included. The mean preop IMA in scarf was 13.1, and 13.6 in MIBA (p= 0.7). Mean postop IMA in scarf was 4.9, and 6.8 in MIBA (p &lt; 0.05). The mean preop HVA in scarf was 25, 28.7 in MIBA (p=0.1). Mean postop HVA in scarf was 5.9, 13.1 in MIBA (p &lt; 0.05). Mean preop AA in scarf was 8.9, 8.9 in MIBA (p= 0.6). Mean postop AA in scarf was 6.3, 6.9 in MIBA (p=0.7). All feet had a significant improvement of IMA and HVA pre and postop (p &lt; 0,005). Scarf preop AA was 8.9 and 6.3 postop, which is a pronation change of -2.5 (p &lt; 0.05). MIBA preop AA was 8.9 and 6.9 postop, which is a pronation change of -2 (p=0.054). Conclusion: To the best of our knowledge, this is the only study that compares WBCT correction between Scarf and MIBA surgery. Both osteotomies have a significant power to correct transverse deformity, scarf corrects significantly better than MIBA when analyzing HVA and IMA. The scarf has a significant power to correct pronation, whereas MIBA shows a strong tendency.

Weight-bearing CT Scan Analysis in Hallux Valgus Treated with Minimally Invasive Surgery

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) is one of the most prevalent foot deformities. Coronal metatarsal rotation (pronation) has been recognized as a key element in HV deformity and an important prognostic factor for recurrence. With the advent of weight-bearing CT (WBCT), accurate pronation measurement has improved. The Minimally Invasive Bosh Akin (MIBA) surgery has proven to be effective in treating HV deformity. The literature analyzing correction of pronation in HV surgery is lacking. Purpose: To compare the transverse and coronal plane deformity correction by WBCT in HV patients treated with MIBA surgery. Methods: We retrospectively analyzed HV deformity in patients who underwent MIBA surgery with preoperative and at least 3 months postoperative WBCT for comparison. Intermetatarsal angle (IMA), hallux valgus angle (HVA), and alpha angle (AA) for first metatarsal pronation were measured by 2 different observers. The intraclass and interclass correlation were determined. Pre and postoperative measurement changes were established by T-test for related samples. the p-value for statistical significance was set at &lt; 0.05. Results: 37 feet were included. Intraclass correlation was 0.97 /0.92 for IMA; 0.95/0.91 for AA and 0.99/0.97 for HVA preoperative. Postop it was 0.97/ 0.96 for IMA, 0.97/0.92 for AA, and 0.98 and 0.96 for HVA. Interclass correlation was 0.95 for IMA; 0.7 for AA and 0.82 for HVA preoperative. Postop, was 0.82 for IMA, 0.8 for AA, and 0.79 for HVA. Mean preoperative / postoperative AA was 8.9 degrees and 6.9 degrees respectively, resulting in a first ray pronation change of –2.0 degrees, p&lt; 0.054. The media preoperative and postoperative IMA was 13.6 degrees and 6.8 degrees, demonstrating a significant change (P &lt; .005). The media preoperative and postoperative HVA was 28.7 (8.8) and 13.1 (9.0), demonstrating a significant change (P &lt; .005). Conclusion: To the best of our knowledge, this is the first study that evaluates the radiological changes in HV surgery with WBCT. The MIBA osteotomy for HV deformity has significant power to correct the transverse plane deformity. Even though the coronal plane deformity correction wasn’t statistically significant, it showed a strong tendency, which might be demonstrated by utilizing a bigger sample. The only measurement that didn’t have an excellent agreement was the preop AA.

Talar Neck Rotation Angle in Adults with Clubfoot Deformity: Observed Values and Intra- and Inter- Observer Reliability using Weightbearing CT

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Adults presenting with symptomatic clubfoot represent a challenging cohort of patients. An appreciation of the location and degree of deformities is essential for management. Talar anatomy is often abnormal with varus within the talar neck, however, there are few reproducible methods which quantify talar neck deformity in adults. We describe a technique of assessing talar neck deformity, and report on observed values and intra- / inter-observer reliability. Methods: This was a single-centre, retrospective study including 96 feet from 56 adult patients with clubfeet (82 feet had clubfoot deformity, 14 were normal). Mean age was 34.3±16.9 years and 31 (55.3%) were male. Weight-bearing CT scans captured as part of routine clinical care were analysed. Image reformats were oriented parallel to the long axis of the talus in the sagittal plane. In the corresponding axial plane two lines were drawn (on separate slices): 1) a line perpendicular to the intermalleolar axis, 2) a line connecting the midpoints of the talar head and narrowest part of the talar neck. The talar neck rotation angle (TNR angle) was the angle formed between these lines. Intraclass correlation coefficients (ICC) were performed for intra- and inter-observer reliability. Results: Mean TNR angle in clubfeet was 27.6±12.2 degrees (95%CI = 25.0 to 30.2 degrees). Mean TNR angle in normal feet was 18.7±5.1 degrees (95%CI = 16.0 to 21.4 degrees) (p &lt; 0.001). The ICC for clubfeet was 0.944 (95%CI = 0.913 to 0.964) for intra- observer agreement, and 0.896 (95%CI = 0.837 to 0.932) for inter-observer agreement. Conclusion: This measurement technique demonstrated excellent intra- and inter-observer agreement. It also demonstrated that compared to normal feet, clubfeet had about 9 degrees of increased varus angulation of the talar neck. This technique and data may be used for future research into clubfoot deformity and in planning treatment.

Evaluate the Influencing Factors of Congruency of the First Metatarsophalangeal Joint in Hallux Valgus Based on Weightbearing CT

The purpose of this study was to explore the difference between congruency and incongruency of the first metatarsophalangeal (MTP) joint in hallux valgus using weightbearing CT (WBCT) and to identify the risk factors for incongruency. From January 2019 to January 2021, WBCT scans were retrospectively analyzed for 110 (191 feet) consecutive patients. According to whether the metatarsal articular surface and phalanx articular surface were parallel, they were divided into congruency (73 feet) and incongruency groups (118 feet). The age, intermetatarsal angle (IMA), hallux valgus angle (HVA), distal metatarsal articular surface angle (DMAA), first metatarsal coronal pronation angle (α angle), tibial sesamoid 7 positions (TSP), and tibial sesamoid coronal grading (TSCG) were compared between the 2 groups. Binary logistic regression was used to analyze the influencing factors of incongruency. Receiver operating characteristic (ROC) curve analysis was applied to determine the cutoff value. There were significant differences in IMA, HVA, DMAA, α angle, age, TSP, and TSCG between congruency and incongruency groups (p < .05). Binary logistic regression analysis showed that TSCG, HVA, α angle were the influencing factors of incongruency. ROC curve analysis demonstrated that the cutoff values for incongruency were 1 position for TSCG (sensitivity: 0.835; specificity: 0.884) with the area under curve (AUC) of 0.892, 30° (sensitivity: 0.795; specificity: 0.812) for HVA with the AUC of 0.878, and 24° (sensitivity: 0.530; specificity: 0.797) for α angle with the AUC of 0.686. Incongruency of the first MTP joint indicated a more severe hallux valgus, and was associated with increased HVA, α angle, and TSCG.

Implementing automated 3D measurements to quantify reference values and side-to-side differences in the ankle syndesmosis

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.