Peritalar Subluxation Research Articles

Chopart Peritalar Subluxation in Progressive Collapsing Foot Deformity Assessed by Three- Dimensional Coverage Maps

Category: Hindfoot; Midfoot/Forefoot; Other Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a complex three-dimensional (3D) deformity characterized by peritalar subluxation (PTS) of the hindfoot through the triple joint complex. In this context, adjacent structures adopt different positions, and bone relations change, producing areas of higher or less contact and stress. The objective of this study was to use 3D distance maps (DMs) and coverage maps (CMs) from weightbearing CT (WBCT) images to assess subluxation across the Chopart joint in PCFD patients. We hypothesized that CMs would show decreased coverage indicative of subluxation through regions of the Chopart joint in PCFD patients when compared to controls. Methods: In this IRB-approved, retrospective case-control study, we analyzed WBCT data of 20 consecutive patients with flexible PCFD and 20 controls. Using principle component analysis, coverage area was divided into six regions on the talar head and 4 on the calcaneal-cuboid articular surface. Novel 3D distance mapping (DM) technique was used to objectively characterize joint coverage across the entire Chopart surface on both talus and calcaneus. Distance maps were measured in millimeters and colored to highlight covered areas. Distances less than 4mm were defined to be covered, while areas with distances greater than 4mm uncovered. Joint coverage was defined as percentage of articular area with DMs lower than 4 mm. Coverage Maps (CM) were built highlighting areas of coverage (teal) versus non-coverage (pink). The Foot and Ankle Offset (FAO) was used as a reference semi-automatic three-dimensional measurement. Comparisons were performed with independent t-tests, assuming unequal variances and p-values <.05 considered significant. Results: Changes in coverage percentages of PCFD cases relative to controls are indicated in the attached figure. The superomedial and the inferomedial regions of the talar head were found to have a 75% and 79% decrease in coverage in PCFD cases relative to the controls (ps<0.003). The medial side of the head had an overall increase in coverage (ps<0.002). On the calcaneus, the calcaneal-cuboid joint plantar region was found to have a significant coverage decrease of 12% relative to the controls (p=0.037), while the lateral quadrant observed a 13% increase (p=0.002). DMs evaluation showed no significant differences in the mean distances for either the calcaneocuboid or the talonavicular (ps>0.05). The FAO was found to be correlated with changes in talar and calcaneal coverages (rs=0.90; R2=0.81). Conclusion: Our results support the hypothesis that significant changes occur at the Chopart joint in early flexible PCFD cases. Increased coverage in the lateral region of the talar head and decreased coverage in the medial and plantar regions point to internal rotation of the talus indicating subluxation through the entire joint. This behavior was also translated in the calcaneal- cuboid, where plantar and medial areas had a decrease in coverage. Coverage 3D mapping enabled objective subluxation quantification through the Chopart joint in early-stage PCFD. These findings may assist clinical assessment of normal joint alignment restoration during PCFD corrections.

Surgical Correction of Peritalar Subluxation and Patient-Reported Outcomes: A Prospective Comparative Outcome Study in Flexible Progressive Collapsing Foot Deformity

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:Peritalar subluxation (PTS) of the hindfoot is a critical finding in Progressive Collapsing Foot Deformity (PCFD). Subluxation of the middle facet and sinus tarsi recently been shown to represent essential markers of pronounced and potentially progressive deformity. Weightbearing CT (WBCT) imaging and three-dimensional (3D) distancing coverage maps (CM) allow a complete and accurate assessment of PTS markers across the entire peritalar surface. This prospective comparative study aimed to assess the effectiveness of joint-sparing realignment surgical treatment for flexible PCFD in reducing PTS and to correlate the improvement with patient-reported outcomes (PROs). We hypothesized that would significantly improve PTS markers, mainly decreasing sinus tarsi coverage/impingement and middle facet subluxation, and that this improvement would correlate with increased PROs.Methods:In this IRB-approved prospective and comparative study, we enrolled patients with flexible PCFD, no prior surgeries, and failed conservative treatment. Included females/3 males, mean age 57.2, range 37-74) underwent joint-sparing surgical realignment procedure by a single surgeon. Standing weightbearing CT (WBCT) was complete 3-months postoperatively.Following automatic bone segmentation, 3D distance maps (DMs) of the entire peritalar surface were generated, and coverage of the subtalar joint (anterior, middle, and posterior) and sinus tarsi were assessed as markers of PTS. Joint coverage was defined as the percentage of articular space where DMs were <5 mm. CM were built highlighting areas of adequate joint interaction (blue), joint subluxation (pink), and impingement (red). PROs were evaluated preoperatively and at the latest follow-up between preop/postop measurements and PROs were assessed by independent t-tests/Wilcoxon and bivariate analysis. P-values <.05 were considered significant.Results:The overall follow-up was 8.2 months (6-13 months). Medial displacement calcaneal osteotomies, lateral column lengthening, and first ray realignment procedure osteotomy or Lapidus) were performed in all patients. Foot and Ankle Offset significantly improved from 10.6% preoperatively to 3.1% postoperatively (p=0.0005), on averaged improvement was also observed in anterior facet joint coverage (61.6%), as well as a reduction in sinus tarsi coverage/impingement (-43.2%) (both p<0.001). Middle posterior facet joint coverage (3.5%, p=0.06) also demonstrated improvements, however not significant. PROs improved significantly on average postoperatively, with the E Ankle Surgery (EFAS) Score increasing from 3.1 to 7.3 (p=0.02) and the Foot Function Index (FFI) improving from 71.5 to 48.7 (p=0.01). Improvements in EFAS scores and FFI s with improvements in middle facet coverage (R2 0.89, p=0.0154) and anterior facet coverage (R2 0.80, p=0.04), respectively.Conclusion:Our study was the first to evaluate WBCT 3D distance mapping's role in the assessment of surgical correction of PTS in patients with PCFD. We found significant subtalar joint anterior facet coverage and sinus tarsi impingement following surgical reconstruction, with a trend to significant improvements in middle and posterior facet j importantly, improvements in middle and anterior facet coverage correlated significantly with improved PROs (EFAS score and FFI, respectively).Significance/Clinical Relevance: Based on our study results, optimization of subtalar joint coverage and reduction of PTS should be goals of surgical treatment of PC

Predictors of Deformity in Patients with Progressive Collapsing Foot Deformity and Valgus of the Ankle

Category:Hindfoot; Ankle; Ankle Arthritis; Midfoot/ForefootIntroduction/Purpose:Markers used for diagnosis and severity grading are well studied in patients with Progressive Collapsing Foot Deformity (PCFD). Medial facet subluxation (MFS) in weight-bearing computerized tomography (WBCT) has been established as an early indicator of peritalar subluxation (PTS). When the disease affects the ankle leading to a valgus talar tilt (class E), structures distal to this topography may behave differently, trying to compensate for proximal deformity. The aim of this study is to assess predictors of deformity in PCFD patients with and without valgus of the ankle. Our hypothesis is that MFS cannot be used in Class E patients as an accurate marker for the evaluation and staging of PCFD.Methods:In this IRB-approved retrospective case-control study, we analyzed WBCT imaging of 21 consecutive patients with PCFD with valgus of the ankle and 64 controls (flexible PCFD without ankle involvement). MFS (defined by the percentage of uncoverage), middle facet incongruence angle, middle cuneiform-to-floor distance, forefoot arch angle, talonavicular uncoverage angle, hindfoot moment arm (HMA), Foot and Ankle Offset (FAO), and talar tilt angle (TTA) were obtained and compared between groups using one-way ANOVA. A multivariate regression analysis was performed to evaluate which of the measurements influenced the alignment. A partition prediction model was constructed to assess how the variables contributed to the deformity. P values <0.05 indicated statistical significance.Results:Differences between groups were found for MFS, HMA, FAO, and TTA, with a lower mean value of MFS in PCFD patients with valgus of the ankle. An inverse relation between MFS and TTA was found, which was demonstrated by an increase in the talar tilt and a decrease in middle facet uncoverage. FAO values were affected by MFS in the control group (R2: 0.25) but not in the ankle valgus group (R2: 0.001), which was influenced mainly by the TTA (R2: 0.53). Additionally, a FAO value higher than 12.14 was found to be a strong predictor of deformity at the ankle.Conclusion:Medial facet subluxation was lower in patients with PCFD and valgus of the ankle (Class E), which demonstrates that MFS is a weak predictor of deformity severity. Therefore, this suggests that talar tilt angle and Foot and Ankle Offset should be used as disease markers in this group of patients. Furthermore, a FAO value above 12.14 may be an indicator of ankle involvement in PCFD patients.

Influence of Weight-Bearing Computed Tomography in the New Staging System of Progressive Collapsing Foot Deformity Classification

Category:Ankle; Hindfoot; Midfoot/Forefoot; OtherIntroduction/Purpose:The same Consensus that proposed a new nomenclature for Flatfoot, Progressive Collapsing Foot Deformity (PCFD), also introduced a new classification system for the disease. The idea of staging was supplemented by the construction of a system combining deformity classes and its flexibilities, using clinical and radiographic signs. The capacity of the weight-bearing computed tomography (WBCT) in evaluating PCFD and all components of peritalar subluxation has been established. The objective of this study was to compare PCFD classifications performed utilizing clinical and conventional radiographs (CR) findings with classifications established using clinical and WBCT findings. We hypothesized that evaluations considering WBCT would significantly change PCFD classifications, portraying a different picture of the disease.Methods:This retrospective IRB-approved case-control diagnostic study evaluated 89 consecutive PCFD feet (84 patients) with different presentations of the disease. Three fellowship-trained foot and ankle surgeons performed chart reviews and CR evaluations, determining PCFD classifications for the studied subjects. After a two-week washout period, the sequence was randomized, and a new classification was executed using clinical data and WBCT assessment. One of the readers repeated the WBCT evaluation two weeks later for intrarater reliability purposes. Assessments included the presence or absence of classes, such as hindfoot valgus (A), midfoot abduction/sinus tarsi impingement (B), medial column instability (C), subtalar joint subluxation/subfibular impingement (D), and valgus of the ankle joint (E) as well as flexibility (1) and rigidity (2) of existing deformities. Fleiss kappa was used for interrater and Cohen's kappa for intrarater agreements. Differences between studied groups were determined by distribution comparison.Results:Mean BMI and age were 54.4 (+-17.1) and 33.6 (+-7.6) respectively. Interrater reliability was found to be moderate (0.55) and intrarater to be excellent (0.98). Evaluation using CR produced 22.8% of 1ABC, 13% of 1AC, 8,7% of 1ABCD and 7% of 2EABCD as most prevalent classifications. WBCT assessment found 31.5% of 1ABC, 11.2% of 1ABCD, 10.1% of 2ABCDE and 5.6% 1ABCDE. Class A was the most frequent component in CR (93.5%) and WBCT (94.5%). Class B had a higher prevalence in WBCT (94.38%) than in CR (71.7%) as well as Classes C (89.9% and 88.0%), D (44.9% and 29.3%) and E (31.5% and 23.9%). The percentage of combined flexible (1) and rigid (2) deformities was also higher in the WBCT evaluation (39.3% compared to 35.8%).Conclusion:As the new classification proposes the combination of different PCFD components to better support clinical decisions, proper identification of the classes is mandatory for a complete diagnosis. WBCT showed a different rate of deformity recognition, which increased the incidence of all classes, especially B (midfoot abduction/sinus tarsi impingement) and D (peritalar subluxation/subfibular impingement). An excellent intrarater agreement was found, which infers reliability of patient assessment combining clinical and WBCT evaluation. The obtained information could help providers to enhance comprehension of the disease and to supply patients with the most precise individual care.

Peritalar Subluxation: A Key Finding for Both Cavovarus and Flatfoot Deformities

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:Peritalar subluxation in both the talonavicular and subtalar joints has been described as characteristic markers for adult acquired flatfoot deformity (AAFD). However, no study has reported these changes in in cavovarus deformity, and we postulated that peritalar subluxation would apply to both the AAFD as well as the cavovarus foot deformity but in different directions using the same markers. Furthermore, the use of calcaneocuboid (CC) joint subluxation as an additional marker for peritalar subluxation has never been investigated in either flatfoot or cavovarus deformities. This study used three dimensional images of weightbearing cone beam computed tomography (WBCT) to evaluate the alignment of the peritalar joints in feet with normal, varus and valgus hindfoot alignment.Methods:WBCT scan images and medical charts of 400 patients were retrospectively reviewed. Thirty cavovarus and 15 flexible AAFD feet were chosen as the study groups. Fifteen feet without deformities and arthritis, a history of trauma or surgery in both the hindfoot and ankle were chosen as controls. Hindfoot moment arm (HMA), Foot and ankle offset (FAO) were used to assess hindfoot alignment. Middle facet subluxation (MFS), talonavicular joint coverage angle (TNCA), and calcaneocuboid joint subluxation (CCS) were used as markers of peritalar subluxation. The talocalcaneal (Kite's) angle in the axial plane was used to demonstrate the relative position between the talus and the calcaneus. The arch height index in the sagittal plane was used to assess medial arch height. Positive was used to reflect lateral subluxations while negative for medial ones. Correlations between HMA, FAO and each of the above three peritalar subluxation parameters were assessed by bivariate linear regression.Results:Patients in both the cavovarus and the AAFD groups showed totally different hindfoot alignment, peritalar subluxation and the height of the medial arch compared to the control group. In the order of Cavovarus, AAFD, and Control, the mean HMA- CR values were -20.43mm, 14.02mm, and 0.03mm, respectively; HMA-WBCT values were -6.34mm, 15.75 mm, and 3.19 mm; FAO values were -11.17%, 7.42%, and 2.63%; TNCA were -16.8 degrees, 22.11, and 6.45; The MFS values were -17%, 42%, and 22%; CCS values were -21% (IQR=-35%,-0.17%), -7% (IQR=-11%, 0) and 0 (IQR=-4%, 5%); The Kite's angles were 22.19 degrees, 34.27 degrees, and 28.06 degrees; The arch height index values were 0.25, 0.71, and 0.44. There was a statistically significant difference among the three groups in all the above parameters. There was a strong positive linear correlation between each parameter of the peritalar subluxation marks with both hindfoot moment arm and FAO.Conclusion:This is the first study to bring the concept of peritalar subluxation to cavovarus deformity assessment, proving that peritalar subluxation is a key characteristic in both flatfoot and cavovarus foot deformities. The two deformities are pathologically completely different, and as expected, markers of peritalar subluxation were in opposite directions. The use of calcaneocuboid joint subluxation as additional marker of perisubtalar subluxation is novel to assess both deformities. The findings of this study will provide useful guidelines for future clinical evaluation and decision making in treating patients with either varus or valgus hindfoot deformities.

Prevalence and Pattern of Lateral Impingements in the Progressive Collapsing Foot Deformity

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:Lateral impingements, subdivided into Sinus Tarsi (STI), Talo-Fibular (TFI), and Calcaneo-Fibular (CFI) impingements, appear to be associated with the Peritalar Subluxation (PTS) component of the Progressive Collapsing Foot Deformity (PCFD). This is not yet confirmed, as the chronological place of the different types of lateral impingements in PTS is unknown. It is also unclear whether STI are associated with PTS or Midfoot Abduction. Our primary objective was to assess the amount of PTS in STI, TFI and CFI. Our secondary objective was to determine the position of STI among the PTS and Midfoot Abduction deformities. We hypothesized that STI and TFI will be associated with a lower amount of PTS than CFI and that STI will be part involved in both PTS and Midfoot Abduction deformities.Methods:A retrospective study including 72 PCFD assessed with Weight Bearing Computed Tomography (WBCT) was realized. Patients under 15 or with a previous history of surgery were excluded. Lateral impingements were assessed on WBCT images and subdivided as STI, TFI and CFI. Both direct and indirect signs of impingement were considered positive. The amount of PTS was assessed by the percentage of uncoverage and the incongruence angle of the Middle Facet (MF). Midfoot-Abduction was assessed by Talonavicular coverage angle and global foot deformity by Foot and Ankle Offset (FAO). These data were collected by two independent observers and one performed a blinded second assessment. Interobserver and Intraobserver reliabilities were determined using unweighted Cohen's kappa values for lateral impingements and using intraclass correlation coefficients for the measurements. Impingement groups were compared using Student's T-tests for normal, and Mann-Whitney for non-normal variables.Results:Interobserver and Intraobserver reliabilities ranged from substantial to almost perfect for all assessments. STI was present in 84.7%, TFI in 65.2% and CFI in 19.4% of PCFD cases. PCFD with STI showed significant increases of MF uncoverage (p=0.0001), FAO (p=0.0008) and Talonavicular coverage angle (p=0.0197) compared to PCFD without STI. PCFD with TFI did not show significant difference on measurements compared to PCFD without TFI. PCFD with CFI had associated STI in 100% and TFI in 64.2% of cases. PCFD with CFI showed significant decreases of MF incongruence (p=0.0398) and significant higher FAO (p=0.0058) compared to PCFD without CFI. PCFD with both STI and CFI showed significant decreases of MF incongruence (p=0.032) and significant higher FAO (p=0.028) compared to PCFD with isolated STI.Conclusion:Our hypotheses have not been confirmed. STI was associated with both PTS and Midfoot Abduction deformities but neither TFI nor CFI were associated with PTS considering MF subluxation. Conversely, CFI was associated with a reduction of the MF incongruence angle despite being associated with a higher global deformity. STI may be associated with earlier PCFD with a concentration of the malignment forces in the subtalar joint whereas CFI may occur later and be associated with a failure of the deep layer of the deltoid ligament and a talar tilt. This could explain the relative reduction of the PTS in CFI.

Validation and Reliability of the Progressive Collapsing Foot Deformity (PCFD) Classification

Category:Midfoot/Forefoot; OtherIntroduction/Purpose:Recently, a group of experts proposed Progressive Collapsing Foot Deformity (PCFD) as a new terminology to describe better the complexity of this pathology, as well as a new staging system based on rigidity and different patterns of deformity. The proposed system (Table 1) better incorporates recent data and understanding of the condition, better allowing for standardization of reporting, and guiding treatment decision-making to achieve optimal outcomes. The classification includes two Stages: flexible (1) and rigid (2) deformity each of which may or may not be associated with five subclasses of deformity including hindfoot valgus (A), midfoot abduction (B), forefoot supination (C), peritalar subluxation (D), and ankle valgus instability (E). This paper aims to determine the reliability and the validity of the PCFD classification system.Methods:This is a survey-based study distributed through REDCap. Participants were provided with video and case examples explaining how the classification system is used. Three groups of surgeons (Group 1 fellows in training, Group 2 surgeons in practice for 1-4 years, and Group 3 in practice 5 years or more) classified 20 cases of PCFD. Correct response rates for the 20 cases, and subclasses and substages of each individual case were calculated. The mean and 95% confidence interval were used to describe normally distributed numerical data. Values of the above parameters were compared among the three different groups using Tukey-Kramer HSD test of Oneway ANOVA. P<0.05 was considered statistically significant.Results:Ninety-four of 113 returned surveys were completed and included in the analysis. There were 18 in Group 1, 23 in Group 2, and 53 in Group 3, with significantly different overall correct diagnosis rates (75.8%, 51.7%, and 37.6% respectively). There was no significant difference among the three groups with regard to the correct response ratio of different Stages. The correct response rates for each Class of deformity were 96.62% (95% CI=94.02%, 99.23%) for Class A (hindfoot valgus); 77.66% (95% CI=75.06%, 80.26%) for Class E (ankle instability); 87.98% (95% CI=85.38%, 90.58%) for Class B (midfoot abduction), 87.99% (95% CI=85.39%, 90.60%) for Class C (forefoot supination) and 57.29% (95% CI=54.70%, 59.90%) for Class D (peritalar subluxation), with the correct response rates of Class A, B, C and E being significantly higher than that of Class D.Conclusion:Three groups of surgeons with varied experience demonstrated a higher accuracy of responses for hindfoot valgus, and ankle instability and a lower accuracy for midfoot abduction, forefoot supination and peritalar subluxation. The classification as presented to the reviewers provided sufficient information to guide accurate decision making for correct responses, however some classes of deformity, in particular peritalar subluxation may have been poorly defined in the clinical presentations and may require more clinical and radiographic information to guide decision making for correct classification.

Three-Dimensional Distance and Coverage Maps in the Assessment of Peritalar Subluxation in Progressive Collapsing Foot Deformity

Category:Ankle; Basic Sciences/Biologics; Hindfoot; OtherIntroduction/Purpose:Progressive collapsing foot deformity (PCFD), formerly termed Adult-Acquired Flatfoot Deformity (AAFD), is a complex 3-dimensional (3D) deformity characterized by peritalar subluxation (PTS) of the hindfoot through the triple joint complex. PTS severity is typically measured at the posterior facet of te subtalar joint, but recent studies have called this into question and presented the middle facet as a more accurate marker of deformity. The objective of this study was to use 3D distance mapping (DM) from weightbearing computed tomography (WBCT) images to assess PTS in PCFD patients and controls across the entire peritalar suface. We hypothesized that 3D DMs would identify the middle facet as a superior marker for PTS, as well as indicate increased extra-articular sinus tarsi and subfibular inpingements in PCFD patients.Methods:In this case control study, we analyzed WBCT data of 20 consecutive patients with flexible PCFD and 10 controls. Novel 3D distance mapping (DM) technique was used to objectively characterize joint coverage across the entire peritalar surface, including both articular (anterior, middle and posterior facets of the subtalar joint) and nonarticular regions (sisus tarsi and subfibular areas). Distance maps were measured in millimeters, and colored to highlight regions of interest. Distances from 1-4mm were shown in blue to indicate expected joint interaction/extra-articular proximity, while distances under 1mm were highlighted in yellow/red indicating close bone proximity consistent with joint space narrowing (articular) or impingement (extra-articular). Joint coverage was defined as percentage of articular area with DMs <4 mm. Coverage Maps (CM) were built highlighting areas of adequate joint interaction (blue), joint subluxation (pink), and impingement (red). Comparisons were performed with independent t-tests or Wilcoxon tests. P values <.05 were considered significant.Results:Overall, coverage was decreased in articular regions and impingement was increased in nonarticular regions of PCFD patients. Objectively, a significant 46.6% average increase in the uncoverage of the middle facet of the subtalar joint was observed in PCFD patients (p<.001), consistent with signifcant middle facet subluxation when compared to controls. No significant similar uncoverage was identified in the anterior or posterior facets. Extra-articularly, an overall 98% increase in sinus tarsi coverage was identified in PCFD patients (p<.007) with direct sinus tarsi impingement in 6 of 20 patients with PCFD, and one of the controls. Direct subfibular impingement was noted in only 1 of 20 PCFD patients, but subfibular space narrowing greater than 2 standard deviations was noted in 17 of 20 PCFD patients. Attached figures demonstrate examples of distance and coverage maps, as well as a comparative averaged assessment of peritalar surface coverage in PCFD and controls.Conclusion:Our study results revealed that when compared to controls PCFD patients demonstrated that a significant decrease in 3D measures of subtalar joint coverage was only identified in the middle facet, but not at the anterior or posterior facets. We also determined significantly decreased inter-bone distances in the sinus tarsi and subfibular regions of PCFD patients, confirming the occurrence of extra-articular impingement in those areas. We hope that the use of these 3D accurate and objective measures of distance (DM) and coverage maps (CM) of middle facet subluxation will support early detection of PCFD patients at high risk for progressive collapse.

Surgical Correction of Peritalar Subluxation and Patient Reported Outcomes: A Prospective Comparative Outcome Study in Flexible Progressive Collapsing Foot Deformity

Category:Ankle; Hindfoot; OtherIntroduction/Purpose:Peritalar subluxation (PTS) of the hindfoot is a critical finding in Progressive Collapsing Foot Deformity (PCFD). Subluxation of the middle facet and sinus tarsi impingement have recently been shown to represent essential markers of pronounced and potentially progressive deformity. Weightbearing CT (WBCT) imaging and three-dimensional (3D) distance (DM) and coverage maps (CM) allow a complete and accurate assessment of PTS markers across the entire peritalar surface. This prospective comparative study aimed to assess the effectiveness of joint-sparing realignment surgical treatment for flexible PCFD in reducing PTS and to correlate the improvement with patient-reported outcomes (PROs). We hypothesized that surgical treatment would significantly improve PTS markers, mainly decreasing sinus tarsi coverage/impingement and middle facet subluxation, and that this improvement would correlate with increased PROs.Methods:In this IRB-approved prospective and comparative study, we enrolled patients with flexible PCFD, no prior surgeries, and failed conservative treatment. Included patients (n=10, 7 females/3 males, mean age 57.2, range 37-74) underwent joint-sparing surgical realignment procedure by a single surgeon. Standing weightbearing CT (WBCT) was completed preoperatively and 3- months postoperatively. Following automatic bone segmentation, 3D distance maps (DMs) of the entire peritalar surface were generated, and coverage of the subtalar joint articular facets (anterior, middle, and posterior) and sinus tarsi were assessed as markers of PTS. Joint coverage was defined as the percentage of articular space where DMs were <5 mm. Coverage Maps (CM) were built highlighting areas of adequate joint interaction (blue), joint subluxation (pink), and impingement (red). PROs were evaluated preoperatively and at the latest follow-up. Differences between preop/postop measurements and PROs were assessed by independent t-tests/Wilcoxon and bivariate analysis. P-values <.05 were considered significant.Results:The overall follow-up was 8.2 months (6-13 months). Medial displacement calcaneal osteotomies, lateral column lengthening, and first ray realignment procedures (either Cotton osteotomy or Lapidus) were performed in all patients. Foot and Ankle Offset significantly improved from 10.6% preoperatively to 3.1% postoperatively (p=0.0005), on average. Significant averaged improvement was also observed in anterior facet joint coverage (61.6%), as well as a reduction in sinus tarsi coverage/impingement (-43.2%) (both p<0.001). Middle (19.5%, p=0.08) and posterior facet joint coverage (3.5%, p=0.06) also demonstrated improvements, however not significant. PROs improved significantly on average postoperatively, with the European Foot and Ankle Surgery (EFAS) Score increasing from 3.1 to 7.3 (p=0.02) and the Foot Function Index (FFI) improving from 71.5 to 48.7 (p=0.01). Improvements in EFAS scores and FFI significantly correlated with improvements in middle facet coverage (R2 0.89, p=0.0154) and anterior facet coverage (R2 0.80, p=0.04), respectively.Conclusion:Our study was the first to evaluate WBCT 3D distance mapping's role in the assessment of surgical correction of PTS in patients with PCFD. We found significant improvements in subtalar joint anterior facet coverage and sinus tarsi impingement following surgical reconstruction, with a trend to significant improvements in middle and posterior facet joint coverage. More importantly, improvements in middle and anterior facet coverage correlated significantly with improved PROs (EFAS score and FFI, respectively). Based on our study results, optimization of subtalar joint coverage and reduction of PTS should be goals of surgical treatment of PCFD patients.

Hindfoot Varus Deformity: An Essential but Easily Neglected Pathological Change in Müller-Weiss Disease

Category:Hindfoot; Midfoot/Forefoot; OtherIntroduction/Purpose:The key pathology of Müller-Weiss Disease (MWD) is fragmentation of the lateral pole of the navicular which leads to lateral rotation of the talar head, inversion of the subtalar joint, and eventually collapse of the medial arch with a paradoxical flatfoot deformity since the varus heel persists. Treatment for MWD should be based on an understanding of this unusual hind and midfoot deformity in order to achieve ideal outcomes. For years however, some authors have treated MWD as a flatfoot deformity instead of correction of the varus heel. This study used weightbearing CT (WBCT) images to demonstrate the structural and alignment changes of the hindfoot and medial arch in patients with MWD compared to those of controls and patients with adult acquired flatfoot deformity (AAFD).Methods:Twelve patients with 17 feet from two medical centers with a clinical diagnosis of MWD were retrospectively reviewed. Ten feet with flexible AAFD were chosen as the flatfoot control group. Ten feet without deformity, arthritis, a history of trauma, or prior surgical history in the foot and ankle were chosen as normal controls. The hindfoot moment arm (HMA), foot and ankle offset (FAO), middle facet subluxation (MFS), talonavicular joint coverage angle (TNCA), and the percentage of calcaneocuboid joint subluxation (CCS) measured on WBCT were used to assess the alignment of the hindfoot and peritalar joints. The arch height index was used to assess the height of the medial arch. Positive was used to reflect lateral subluxations and negative was for the medial ones. ANOVA test were used to compare data among the three groups with a normal distribution, while Wilcoxon test were used for non normal distribution.Results:According to WBCT analysis, patients with MWD showed totally different hindfoot alignment and peritalar subluxation characteristics compared to the AAFD and the normal control groups. In the order of MWD, AAFD and control, the mean HMA values were -3.44 mm, 15.75 mm, and 3.19 mm, FAO values were -0.72%, 7.42%, and 2.63%. TNCA values were -7.18, 22.11, and 11.37; MFS values were 14%, 45%, and 23%; CCS values were -0.19, 0 and -0.04. The arch height index values were 0.46, 0.45, and 0.58. There was statistically significant difference among the three groups in all the above parameters except the middle facet subluxation and fifth metatarsal medial cuneiform height ratios between the MWD group and the normal controls.Conclusion:This study confirmed that hindfoot varus is a typical feature of MWD. And this is the first study to demonstrate that peritalar subluxation is an important marker. With lateral rotation of the talar head, the subtalar joint is driven into varus, with medial subluxation of both the middle facet and the calcaneocuboid joint, resulting in peritalar subluxation opposite to that of AAFD. No significant difference between the medial arch of the MWD group and the controls was present. In conclusion, structural changes of the midfoot and hindfoot totally different from the characteristics of AAFD are present in MWD.

Intra and Inter-Observer Reliability of the New Classification System of Progressive Collapsing Foot Deformity

Category:Basic Sciences/Biologics; Hindfoot; Midfoot/ForefootIntroduction/Purpose:Over the past three decades, the historical notion that adult acquired flatfoot was attributed to posterior tibial tendon dysfunction (PTTD) has been questioned. Advances in the understanding of arch stabilizers and biomechanics of the midfoot joints have led to the new concept of progressively collapsing foot deformity (PCFD). Most recently, the consensus group proposed a new classification system and recommended renaming PTTD to PCFD. The proposed PCFD classification system incorporates the latest understanding of the condition and provides a concise, standardized description of the deformity. To date, there has been no study reporting the frequency of each subclass of PCFD with various combination of deformity components and evaluating intra- and interrater reliability.Methods:This was a single-center, retrospective study conducted from prospectively collected registry data. 84 patients (92 feet) were assessed between 2014 and 2020. Classification of each patient was made utilizing clinical and radiographic findings by three independent observers. Clinical aspects of the deformity included hindfoot valgus, forefoot/midfoot abduction, forefoot varus deformity, hypermobile medial column, sinus tarsi impingement, peritalar subluxation and valgus tilting of the ankle joint.Radiographic evaluation was focused on Hindfoot valgus (A), increased talar head undercoverage, significant sinus tarsi impingement (B), increased lateral talus-first metatarsal angle, plantar gapping at first TMT/NC joints (C), significant subtalar joint subluxation/subfibular impingement with obliterated joint space (D), and ankle joint valgus tilting with or without arthritic changes (E). Intra- and interrater reliabilities were analyzed with Cohen's Kappa and Fleiss' kappa respectively.Results:Mean age was 54.4, 38% male and 62% female. Mean BMI was 33.6 kg/m2. 1ABC (21 feet, 22.8%) was most common subclass followed by 1AC (12 feet, 13%) and 1ABCD (8 feet, 8.7%). Cumulative percent of frequency of 1ABC, 1AC, and 1ABCD was 44.5%. Only a small percentage of patients had an isolated deformity. 58.7% were flexible, 5.5% were rigid, and 35.8% were combined deformities with flexible and rigid components. A was most frequent component (93.5%) followed by C in 88% and B in 71.7%. D was in 29.4% and E was the least frequently observed component in 23.9%. Moderate inter-rater reliability (Fleiss Kappa=0.561, p<0.001, 95% CI 0.528-0.594) was found. E was the most reliable between raters (91.3%) followed by A (79.4%). D was least reliable between three raters (45.7%). Very good intra-rater reliability was found (Cohen`s Kappa=0.851, P<0.001, 95% CI 0.777-0.926).Conclusion:Most cases predominantly involved hindfoot with various combinations of midfoot and forefoot deformity with/without subtalar joint involvement. This finding suggests most of PCFD exist in combined forms with various deformity components. Despite the limitation of inherent subjectivity, which may account for moderate inter-rater agreement, the new system potentially cover all possible combinations of the deformity in hindfoot, midfoot, forefoot and ankle. This provides a more comprehensive description of PCFD deformity and can guide treatment in a more systematic and individualized manner. Future studies in a larger cohort with advanced imaging are warranted to ascertain reliability and validity of this system.

Three-Dimensional Coverage Maps in the Assessment of Chopart Subluxation in Progressive Collapsing Foot Deformity

Category:Basic Sciences/Biologics; Hindfoot; Midfoot/ForefootIntroduction/Purpose:Progressive collapsing foot deformity (PCFD), formerly termed Adult-Acquired Flatfoot Deformity (AAFD), is a complex 3D deformity characterized by peritalar subluxation (PTS) of the hindfoot through the triple joint complex. In this context, adjacent structures may adopt different positions and boney relations can change, producing areas increased contact or subluxation. The objective of this study was to use 3D distance maps (DMs) and coverage maps (CMs) from weightbearing CT (WBCT) images to assess subluxation across the Chopart joint in PCFD patients. We hypothesized that CMs would show decreased coverage indicative of subluxation through certain regions of the Chopart joint in PCFD patients when compared to the controls.Methods:In this IRB-approved, retrospective case-control study, we analyzed WBCT data of 18 consecutive patients with flexible PCFD and 10 controls. Using principle component analysis, candidate coverage area was divided into nine regions on the talar head and 4 regions on the calcaneal-cuboid (CC) articular surface. Novel 3D distance mapping (DM) technique was used to objectively characterize joint coverage across the entire Chopart joint surface on both the talus and calcaneus. Distance maps were measured in millimeters and colored to highlight covered areas. Areas with distances less than 4mm were defined to be covered, while areas with distances greater than 4mm were considered to be uncovered. Joint coverage was defined as percentage of articular area with DMs lower than 4 mm. Coverage Maps (CM) were created to highlight areas of coverage (teal) versus non- coverage (pink). Comparisons were performed with independent t-tests, assuming unequal variances. P values <.05 were considered significant.Results:Changes in coverage percentages of PCFD cases relative to controls are indicated in attached figure 1. The middle lateral region of the talar head was found to have a 9% increase in coverage in PCFD cases relative to the controls (p = 0.011). The plantar region of the calcaneal-cuboid joint was found to have a 18% decrease in coverage compared to the controls. Except for the dorsal medial regions, the medial side of the talar head saw overall decreases in coverage. However, these values were not statistically significant. On the calcaneus, the plantar region of the calcaneal-cuboid joint was found to have a significant coverage decrease of 18% relative to the controls (p = 0.017). There was also a decrease in coverage observed in the medial region of the calcaneal-cuboid joint and an increase in the dorsal and lateral areas.Conclusion:Our results support the occurrence of significant Chopart joint changes in early flexible PCFD. Increased lateral and decreased medial/plantar talar head coverage point to internal rotation and plantarflexion of the talus. Associated dorsal migration of the cuboid where plantar and medial areas have decreased coverage indicate subluxation through the entirety of the Chopart joint. Novel 3D coverage mapping enabled objective quantification of subluxation though the Chopart joint in early stage PCFD. These findings may assist clinical decision making regarding the restoration of normal joint alignment during PCFD corrections. Further studies are needed to establish thresholds of change associated with degeneration.

A Comparison Between the Bluman et al. Classification and the Progressive Collapsing Foot Deformity Consensus for Flatfeet Assessment

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:Bluman et al. flatfoot classification (2007) is based on the posterior tibial tendon (PTT) rupture leading to a chronological appearance of several foot deformities. Since then, several discordances have been noted in this concept. An expert consensus met recently to update it. Emphasis on posterior tibial tendon rupture was shifted to a non-chronological approach focusing on five different independent foot and ankle deformations and each deformation's flexibility or rigidity. This concept, named Progressive Collapsing Foot Deformity (PCFD), was approved with a strong consensus. The aim of this study was to compare Bluman et al. and PCFD classifications. We hypothesize that both classifications will be intra and interobserver reliable and that the PCFD classification will allow a better distribution of the different types of foot.Methods:We performed a retrospective IRB approved study including 92 flatfeet. Three fellowship trained foot and ankle surgeons studied clinical information and X-rays and classified them in Bluman and PCFD classifications. One performed a blinded second assessment. Bluman classification was analyzed one time as initially described and a second time after removing the Angle of Gissane sclerosis sign. Bluman stage I represents isolated PTT dysfunction, stage II and III Flexible and Rigid Hindfoot Valgus, and stage IV Tibio-Talar Valgus. These stages are progressive and don't allow any combinations. PCFD classifies Hindfoot valgus (A), Midfoot Abduction (B), Forefoot Varus (C), Peritalar Subluxation (D), and Tibiotalar Valgus (E). Combinations of these deformities is allowed. Each deformity can be Flexible (1) or Rigid (2). Interobserver and Intraobserver reliabilities were determined with respectively unweighted Fleiss' and Cohen's kappa values. Descriptive analysis was performed on the 276 readings to highlight discrepancies between classifications.Results:Inter and Intraobserver reliabilities were respectively moderate (K=0.55) and substantial (K=0.62) for Bluman and moderate (K=0.56) and very good (K=0.85) for PCFD. The 276 readings were spread into 10 subgroups in Bluman and 64 in PCFD. 2.9% of the flatfeet were classified Bluman stage I, 31.5% stage II, 43.8% stage III and 21.7% stage IV. Bluman stages II and III were mainly composed of PCFD 1ABC (respectively 40.2% and 28.1%). The most represented Bluman subgroup was IIIB (32.6%) whereas after removing the Angle of Gissane sclerosis sign from the classification it was the IIC subgroup (44.2%). PCFD A, B and C were mainly composed of Bluman subgroup IIIB (respectively 35.7%, 43.6% and 36.2%) and PCFD D and E of Bluman subgroup IVB (31.9% and 73.3%).Conclusion:Both classifications showed moderate reliabilities although the PCFD represented 6 times as many different choices by readers. Bluman stage I was rare, possibly because it is based on PTT dysfunction with little or no deformity. This entity is no longer considered in the PCFD. Bluman stage III, assumed to represent rigid hindfoot varus included numerous flexible PCFD. Main confusion could come from the Angle of Gissane sclerosis sign, which leads to Bluman stage III. This sign is however a sign of extraarticular sinus tarsi impingement which should not lead to a triple arthrodesis as recommended in the Bluman classification.

Three-Dimensional Distance Maps of Ankle and Syndesmotic Joints from Weightbearing CT in Progressive Collapsing Foot Deformity: A Retrospective Case-Control Study

Category:AnkleIntroduction/Purpose:Recently, weightbearing computed tomography (WBCT) has been utilized to provide more comprehensive and accurate assessment of complex foot and ankle deformities, notably to diagnose and stage Progressive Collapsing Foot Deformity (PCFD). The 3D data provided by WBCT has enabled the developed of novel tools like distance mapping (DM), coverage mapping (CM), and volume measurements. Over the past year, novel DM and CM have shown promise in providing sensitive automated measures of peritalar subluxation, a major component of PCFD. However, the early effects of PCFD on the tibiotalar joint have not yet been quantified. This study sought to use DM and CM to objectively characterize the effects of PCFD on the tibiotalar and tibiofibular joints. We hypothesized that changes seen in early PCFD will be identified.Methods:IRB approval for retrospective review of patient data from 2014-2020 was obtained to identify patients with clinical and radiographic diagnoses of PCFD. The first consecutive 20 patients with symptomatic flexible PCFD and high-resolution weightbearing CT examination without arthritis that had not undergone prior surgery were selected and compared with 20 controls. Fully automated volume measurements of the syndesmosis at 1cm, 3cm, and 5cm from the tibiotalar joint were performed as well as of the medial and lateral tibiotalar gutters based on models created in Disior Bonelogic. Distance Maps (DMs) were obtained for the tibiofibular incisura, tibiotalar joint, and gutters. Coverage maps (CMs) were created using the measured 3DDMs to identify joint interaction, subluxation, and impingement. Data were checked for normality using the Shapiro- Wilk W test. Two-tailed independent samples student t-tests or Wilcoxon Tests were used to assess differences between groups.Results:There were significant decreases in coverage of all 3 anterior regions of the tibiotalar joint in PCFD patients when compared to controls along with corresponding significant increases in coverage of all 3 posterior regions (Figure). There were no significant differences in mean or minimum distances in any region of the tibiotalar joint surface. Significant increases in average and minimum DMs of the anterior medial (36%, p<0.01, 19%, p<0.03) gutter were observed with significant decreases in coverage of both anterior medial and anterior lateral regions. Significant decreases in the average and minimum distances of the tibiofibular joint were found anteriorly in PCFD patients compared to controls (-26%, p<0.006). There were no significant differences in overall syndesmotic distance or volume at any level.Conclusion:The results of our study were able to identify that, compared to controls, patients with early stage PCFD demonstrated significant tibiotalar and tibiofibular joint changes ahead of developing the tibiotalar narrowing associated with arthritis and syndesmotic widening associated with instability. Decreases in anterior coverage with increases posteriorly support early plantarflexion of the talus in PCFD. When combined with plantarflexion of the talus and unchanged syndesmotic volume, decreases in anterior tibiofibular distances support the absence of syndesmotic joint instability in early PCFD. Novel tools may assist with clinical decision-making regarding restoration of normal tibiotalar and tibiofibular alignment during PCFD correction.

Short-Term Outcomes of the Lapicotton Technique in the Treatment of Progressive Collapsing Foot Deformity

Category:Midfoot/ForefootIntroduction/Purpose:Medial column instability (MCI) in Progressive Collapsing Foot Deformity (PCFD) is not solely determined by forefoot varus (FV). First ray hypermobility, hallux valgus, midfoot arthritis, gapping at the tarsometatarsal joint and dorsal metatarsal migration are findings associated with MCI. Acknowledgement of this instability requires inclusion of a procedure to the medial column in order to correct the forefoot varus, stabilize the ray and bring the foot to a plantigrade tripod position. Cotton opening wedge medial cuneiform osteotomy and Lapidus tarsometatarsal arthrodesis are procedures of choice in these scenarios. We have combined these 2 procedures into one called Lapicotton. The purpose of this study was to present the short-term outcomes of this technique.We hypothesized that Lapicotton will improve both clinical and radiological outcomes.Methods:We performed an IRB-approved retrospective study comprising 3 PCFDs having benefited from a Lapicotton procedure. Clinical outcomes were assessed with the European Foot and Ankle Society Score (EFAS), the Foot Function Index Score (FFI) and the Pain Catastrophizing Scale (PCS). Radiographic outcomes were assessed using weight-bearing computed tomography (WBCT) assessments. Middle Cuneiform Floor distance, Forefoot Arch Angle, Middle Facet uncoverage percentage, Talonavicular Coverage angle and the Foot and Ankle Offset (FAO) were measured. All these data were both preoperatively and postoperatively collected. Comparison between preoperative and postoperative results were done as described below. The Kruskal-Wallis H-test for independent groups was used to compare median values of the EFAS. The Wilcoxon signed-rank test for paired samples was used to compare preoperative and postoperative variables of FFI and PCS. For the radiographic measurements, normality was assessed using Shapiro-Wilk test. Comparisons were made using Student tests for normal variables and Mann-Whitney for non-normals.Results:This small series included 2 female and 1 male, with a mean age of 56 and a mean BMI of 31.8 kg/m2. Mean follow up was 2.9+/-0.2 (range from 2.7 to 3.1) months. 2 out of 3 patients simultaneously benefited of a Medial Calcaneal Displacement Osteotomy (MDCO 10mm) and a Lateral Column Lengthening (LCL 8mm). The wedge sizes used for the Lapicotton were 8 mm in all cases. Regarding clinical outcomes, EFAS (p=0.79) and FFI (p=0.99) did not showed any significant improvement whereas PCS were significantly improved (Δ=-5.67[-9.2–2.2];p=0.03). Regarding radiological outcomes, fusion was present in all the cases at the maximal follow-up. Middle cuneiform floor distance and Forefoot Arch Angle were significantly increase (respectively Δ=6.9;CI95%=[6.4;7.4];p< 0.01 and Δ=7.5;CI95%=[4.3;10.8]p<0.05). Middle Facet uncoverage was significantly improved (Δ=- 28.8;CI95%=[-33.1;-24.5]p< 0.01). Statistical power of the serie did not allowed comparison regarding the Talonavicular Coverage Angle (Δ=-14;CI95%=[-24;-3.9]) and the FAO (Δ=-3.9;CI95%=[-10.7;2.9]).Conclusion:The Lapicotton procedure showed encouraging outcomes with fusion in all cases at 3 months postoperatively, improvement in pain, correction of forefoot varus and of the of the Peritalar subluxation represented by the Middle Facet Uncoverage. These results should be moderate because other procedures (MDCO and LCL) were performed in 2/3 of the patients, and the outcomes were issued from a small cohort with short-term follow-up. Longer follow-up and a larger cohort are needed to confirm these results.

Predictors of Deformity in Patients with Progressive Collapsing Foot Deformity and Valgus of the Ankle

Category:Ankle; HindfootIntroduction/Purpose:Markers of diagnosis and severity are well studied in patients with Progressive Collapsing Foot Deformity (PCFD). Medial facet subluxation (MFS) in weight-bearing computerized tomography (WBCT) has been established as an indicator of peritalar subluxation and an earlier detector of the disease. When the disease affects the ankle leading to a valgus talar tilt (class E), structures distal to this topography may behavior differently, trying to compensate proximal deformity. The aim of this study is to assess predictors of deformity in PCFD patients with and without valgus of the ankle. Our hypothesis is that MFS could not be used in class E patients as an accurate value for estimation and staging of PCFD.Methods:In this IRB-approved retrospective case-control study we analyzed WBCT acquisitions of 21 consecutive patients with PCFD presenting valgus of the ankle and 64 controls (flexible PCFD with no ankle involvement). MFS (percentage of uncoverage), middle facet incongruence angle, middle cuneiform-to-floor distance, forefoot arch angle, talonavicular uncoverage angle, hindfoot moment arm (HMA), Foot and Ankle Offstet (FAO) and talar tilt angle (TTA) were obtained and compared between groups using oneway ANOVA. A multivariate regression analysis was performed to evaluate which of the measurements influenced the alignment. A partition prediction model was also constructed to find how the variables contributed to the deformity and its aspects. Statistical significancy was set in p values <0.05.Results:We found differences among groups only for MFS, HMA, FAO and TTA, with a lower mean value of MFS in patients with valgus of the ankle. An inverse relation between MFS and TTA was obtained in this group, demonstrated by increase in the talar tilt and decrease in middle facet uncoverage. MFS affected FAO values in the control group (R2: 0.25) but not in the ankle valgus group (R2: 0.001), being that this last one was influenced mainly by the TTA (R2: 0.53). A FAO value higher than 12.14 was found to be a strong predictor of deformity at the ankle.Conclusion:MFS was lower in patients with PCFD and valgus of the ankle, demonstrated as a weak predictor of deformity severity. In this group of patients (class E), talar tilt angle and Foot and Ankle Offset should be used as disease markers. A FAO value above 12.14 must be appreciated as a possible sign of ankle involvement in PCFD patients.

Influence of Weight-Bearing Computed Tomography in the New Staging System of Progressive Collapsing Foot Deformity Classification

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:The same Consensus that proposed a new nomenclature for Flatfoot, Progressive Collapsing Foot Deformity (PCFD), also introduced a new classification system for the disease. The idea of staging was supplemented by the construction of a system combining deformity classes and its flexibilities, using clinical and radiographic signs. The capacity of the weight-bearing computed tomography (WBCT) in evaluating PCFD and all components of peritalar subluxation has been established. The objective of this study was to compare PCFD classifications performed utilizing clinical and conventional radiographs (CR) findings with classifications established using clinical and WBCT findings. We hypothesized that evaluations considering WBCT would significantly change PCFD classifications, portraying a different picture of the disease.Methods:This retrospective IRB-approved case-control diagnostic study evaluated 89 consecutive PCFD feet (84 patients) with different presentations of the disease. Three fellowship-trained foot and ankle surgeons performed chart reviews and CR evaluations, determining PCFD classifications for the studied subjects. After a two-week washout period, the sequence was randomized, and a new classification was executed using clinical data and WBCT assessment. One of the readers repeated the WBCT evaluation two weeks later for intrarater reliability purposes. Assessments included presence or absence of classes, such as hindfoot valgus (A), midfoot abduction/sinus tarsi impingement (B), medial column instability (C), subtalar joint subluxation/subfibular impingement (D) and valgus of the ankle joint (E) as well as flexibility (1) and rigidity (2) of existing deformities. Fleiss kappa was used for interrater and Cohen's kappa for intrarater agreements. Differences between studied groups were determined by distribution comparison.Results:Mean BMI and age were 54.4 (+-17.1) and 33.6 (+-7.6) respectively. Interrater reliability was found to be moderate (0.55) and intrarater to be excellent (0.98). Evaluation using CR produced 22.8% of 1ABC, 13% of 1AC, 8,7% of 1ABCD and 7% of 2EABCD as most prevalent classifications. WBCT assessment found 31.5% of 1ABC, 11.2% of 1ABCD, 10.1% of 2ABCDE and 5.6% 1ABCDE. Class A was the most frequent component in CR (93.5%) and WBCT (94.5%). Class B had a higher prevalence in WBCT (94.38%) than in CR (71.7%) as well as Classes C (89.9% and 88.0%), D (44.9% and 29.3%) and E (31.5% and 23.9%). The percentage of combined flexible (1) and rigid (2) deformities was also higher in the WBCT evaluation (39.3% compared to 35.8%).Conclusion:As the new classification proposes the combination of different PCFD components to better support clinical decisions, proper identification of the classes is mandatory for a complete diagnosis. WBCT showed a different rate of deformity recognition, which increased the incidence of all classes, especially B (midfoot abduction/sinus tarsi impingement) and D (peritalar subluxation/subfibular impingement). An excellent intrarater agreement was found, which infers reliability of patient assessment combining clinical and WBCT evaluation. The obtained information could help providers to enhance comprehension of the disease and to supply patients with the most precise individual care.

Imaging of progressive collapsing foot deformity with emphasis on the role of weightbearing cone beam CT.

The term progressive collapsing foot deformity (PCFD) is currently recommended as the replacement to adult-acquired flatfoot deformity and posterior tibial tendon dysfunction to better reflect its pathology, which consists of a complex three-dimensional deformity involving the foot and ankle. The new consensus has also provided a new classification that requires clinical and radiographic findings for patient stratification into each class. However, conventional radiographs are susceptible to errors resulting from the inadequate positioning of patients, incorrect angulation of the X-ray tube, and overlapping of bone structures. Weightbearing cone beam computed tomography (WBCBCT), which has greater diagnostic accuracy than conventional radiograph, is useful for evaluating progressive collapsing foot deformity to determine medial arch collapse, hindfoot alignment, peritalar subluxation, posterior subtalar joint valgus, intrinsic talus valgus, and lateral extra-articular bone impingement. The present review aimed to discuss the new recommendations for nomenclature, classification, and imaging evaluation of PCFD, with an illustrative and quantitative focus on the measurements used in conventional radiography and WBCBCT. The measurements presented here are important criteria for decision-making.

Prevalence and pattern of lateral impingements in the progressive collapsing foot deformity.

The prevalence of lateral bony impingements [i.e., Sinus Tarsi (STI), Talo-Fibular (TFI) and Calcaneo-Fibular (CFI)] and their association with Peritalar Subluxation (PTS) have not been clearly established for progressive collapsing foot deformity (PCFD).This study aims to assess the prevalence of STI, TFI and CFI in PCFD, in addition to their association with PTS. We hypothesized that STI and TFI would be more prevalent than CFI. Seventy-two continuous symptomatic PCFD cases were retrospectively reviewed. Weightbearing computed tomography (WBCT) was used to assess lateral impingements and classified as STI, TFI and CFI. PTS was assessed by the percent of uncovered and the incongruence angle of the middle facet, and the overall foot deformity was determined by the foot and ankle offset (FAO). Data were collected by two fellowship-trained independent observers. Intra-observer and inter-observer reliabilities for impingement assessment ranged from substantial to almost perfect. STI was present in 84.7%, TFI in 65.2% and CFI in 19.4%. PCFD with STI showed increased middle facet uncoverage (p = 0.0001) and FAO (p = 0.0008) compared to PCFD without STI. There were no differences in FAO and middle facet uncoverage in PCFD with TFI and without TFI. PCFD with CFI was associated with STI in 100% of cases. PCFD with CFI showed decreased middle facet incongruence (p = 0.04) and higher FAO (p = 0.006) compared to PCFD without CFI. STI and TFI were more prevalent than CFI in PCFD. However, only STI was associated with PTS. Conversely, CFI was associated with less PTS, suggesting a different pathological mechanism which could be a compensatory subtalar behavior caused by deep layer failure of the deltoid ligament and talar tilt.

Distal Tibiofibular Syndesmotic Widening in Progressive Collapsing Foot Deformity.

Lateral overload in progressive collapsing foot deformity (PCFD) takes place as hindfoot valgus, peritalar subluxation, and valgus instability of the ankle increase. Fibular strain due to chronic lateral impingement may lead to distraction forces over the distal tibiofibular syndesmosis (DTFS). This study aimed to assess and correlate the severity of the foot and ankle offset (FAO) as a marker of progressive PCFD with the amount of DTFS widening and to compare it to controls. In this case-control study, 62 symptomatic patients with PCFD and 29 controls who underwent standing weightbearing computed tomography (WBCT) examination were included. Two fellowship-trained blinded orthopedic foot and ankle surgeons performed FAO (%) and DTFS area measurements (mm2). DTFS was assessed semiautomatically on axial-plane WBCT images, 1 cm proximal to the apex of the tibial plafond. Values were compared between patients with PCFD and controls, and Spearman correlation between FAO and DTFS area measurements was assessed. P values of less than .05 were considered significant. Patients with PCFD demonstrated significantly increased FAO and DTFS measurements in comparison to controls. A mean difference of 6.9% (P < .001) in FAO and 10.4 mm2 (P = .026) in DTFS was observed. A significant but weak correlation was identified between the variables, with a Þ of 0.22 (P = .03). A partition predictive model demonstrated that DTFS area measurements were highest when FAO values were between 7% and 9.3%, with mean (SD) values of 92.7 (22.4) mm2. To our knowledge, this was the first study to assess syndesmotic widening in patients with PCFD. We found patients with PCFD to demonstrate increased DTFS area measurements compared to controls, with a mean difference of approximately 10 mm2. A significantly weak positive correlation was found between FAO and DTFS area measurements, with the highest syndesmotic widening occurring when FAO values were between 7% and 9.3%. Our study findings suggest that chronic lateral impingement in patients with PCFD can result in a negative biomechanical impact on syndesmotic alignment, with increased DTFS stress and subsequent widening. Level III, retrospective comparative study.