Collapsing Foot Research Articles

Ability of the Posterior Tibial Tendon to Restore Foot Alignment in Progressive Collapsing Foot Deformity: A Computational Study

Category:Ankle; Midfoot/Forefoot; OtherIntroduction/Purpose:Progressive collapsing foot deformity (PCFD) is a degenerative disorder of ligaments and tendons that encompasses a wide range of deformities, including arch height loss, hindfoot valgus, and forefoot abduction. The posterior tibial tendon (PTT) is the main active stabilizer of the arch. We hypothesize that it may become injured secondarily as it attempts to maintain foot stability when the ligaments, passive stabilizers, are attenuated. Several cadaveric studies have been conducted on the role of the PTT in PCFD, but the ability of the PTT to compensate for the loss of the ligamentous stabilizers has not been clearly characterized. We developed a high-fidelity finite element model of the foot to determine the PTT's ability to maintain foot stability when the principle ligamentous stabilizers are attenuated.Methods:The encapsulating soft tissue (EST), cartilage, and cortical and trabecular bones were reconstructed in Mimics from CT scan images of a female cadaveric foot weighing 60 kg. Tension-only spring elements were used to reflect all the ligaments in ANSYS. Bodyweight and tendon forces were applied using force vectors in the direction of their lines of action. The proximal tibia was fixed only in the vertical direction, allowing it to translate and rotate in all other degrees of freedom. Nonlinear frictional contacts were used between the EST and the ground, and between the cartilages. The flatfoot was simulated by removing all of the ligaments. We measured the foot alignment angles for the flatfoot and the foot with ruptured spring/deltoid ligament, while we gradually increased the force within the PTT. The measured angles were then compared to the intact foot to evaluate the ability of the PTT to restore foot alignment.Results:The models were validated by comparing the Meary's (MA), calcaneal pitch (CPA), hindfoot alignment (HAA), and talonavicular coverage angles (TCA) to clinically-derived values. In the flatfoot, an increase of the PTT force to approximately 700% of normal ('7 ×25.71 N=180 N') led to a nearly complete restoration of foot alignment (Fig. 1). The angles associated with arch height (MA/CPA) were restored to a lesser extent than those associated with hindfoot and forefoot alignment (HAA/TCA). For the foot with ruptured deltoid ligament, increasing force within the PTT by 500% led to a restoration of near normal hindfoot alignment (Fig. 1c). For the foot with ruptured spring ligament, the forefoot abduction was completely compensated only when the PTT force was increased to 1100% of normal (Fig. 1d).Conclusion:Almost seven times the normal PTT force is required to restore the foot to neutral alignment. Augmentation of PTT force to this extent is unrealistic. However, a lesser increase in PTT force provides partial alignment compensation.Furthermore, the restoration achieved by overloading the PTT primarily impacts the alignment of the hindfoot and forefoot rather than the arch. Because the PTT can partially restore foot alignment, it may become secondarily injured when the ligaments are torn. Strengthening of the PTT through therapeutic exercise can improve its ability to restore foot alignment and should be a cornerstone of non-operative treatment of PCFD.

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.

Does Tibialis Posterior Dysfunction Correlate with Overall Foot Deformity in Progressive Collapsing Foot Deformity?

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:Posterior Tibial Tendon (PTT) dysfunction is considered to play an important role in Adult Acquired Flatfoot Deformity recently renamed Progressive Collapsing Foot Deformity (PCFD). Previous flatfoot classifications are mainly based on a progressive mechanical failure of the PTT causing chronological appearance of deformities. A consensus of experts recently met and decided to remove the central place of the PTT dysfunction from the PCFD classification system. The primary objective of our study was to assess the relation between the PTT clinical status and the three-dimensional overall foot deformity. The secondary objective was to assess the relation between the degeneration of PTT at the MRI and the three- dimensional overall foot deformity. We hypothesized that the more damaged the PTT, the more severe the deformity of the foot.Methods:We retrospectively identified all symptomatic PCFD over 18 years old who consulted our center from 01/01/2019 to 12/31/2020. PCFD with concomitant (< 3 mois) clinical examination, Weight-Bearing CT (WBCT) and MRI were included. PCFD presenting with previous surgical intervention were excluded. Finally 25 PCFD were included in the analysis (19 Women, mean age 53.96+/-14.9 years, mean BMI 33.2+/-8.1 kg/m2;)A PCFD presenting either a deficit on the single heel rise test or a decrease in inversion strength (superior or equal to 3/5) was classified PTT deficient. The MRI of all these PCFD were analyzed, and PTT degeneration was classified according to Deland and Rosenberg classifications. The three-dimensional overall deformity of each PCFD was assessed on WBCT by the Foot and Ankle Offset (FAO). Normality of different variables were assessed using Shapiro- Wilk test. Comparisons were performed using Student's t-test or Anova for normal, and Mann-Whitney or Kruskal-Wallis's test for non-normal variables.Results:Patients with clinically deficient PTT (13/25 PCFD, 52%) had a mean FAO of 7.75+/-3.8% whereas patients without PTT deficit (12/25 PCFD, 48%) had a mean FAO of 6.68+/-3.9%, without significant difference between groups (p=0.49). According to Deland classification, 4/25 PTT (16%) were classified grade 0, 7/25 (28%) grade 1, 4/25 (16%) grade 2, 5/25 (20%) grade 3 and 5/25 (20%) grade 4 without any significant difference between groups (p=0.36).According to Rosenberg classification, 4/25 PTT (16%) were classified type 0, 15/25 (60%) type 1, 2/25 (8%) type 2 and 4/25(16%) type 3 without any significant difference between groups (p=0.79).Seven PCFD had a FAO>10%. Among them, 42.9% had a PTT without clinical deficit and 57.1% had a PTT with little or no damage on the MRI. Nine PCFD had a FAO<5%. Among them, 44.4% had a PTT clinically deficient and 22.2% had a PTT with important damage on the MRI.Conclusion:The importance of three-dimensional overall foot deformity in PCFD was neither correlated with the clinical presence or absence of PTT deficiency, nor with the PTT degeneration on MRI in our study. A patient with important deformity may have an intact PTT and a patient with small deformity can present a deficient PTT. Despite the obvious lack of power in this study, it does not appear that PTT plays a significant role in the PCFD overall deformity.

Intra and Interobserver Reliability of the New Classification System of Progressive Collapsing Foot Deformity

Category:OtherIntroduction/Purpose:Historical concept of flatfoot as posterior tibial tendon dysfunction (PTTD) has been questioned. Recently, the consensus group published a new classification system and recommended renaming PTTD to Progressive Collapsing Foot Deformity (PCFD). The new PCFD classification could be effective in providing comprehensive information on the deformity. To date, there has been no study reporting intra- and interobserver reliability and the frequency of each class in PCFD classification.Methods:This was a single-center, retrospective study conducted from prospectively collected registry data. A consecutive cohort of PCFD patients evaluated from February 2015 to October 2020 was included, consisting of 92 feet in 84 patients. Classification of each patient was made utilizing characteristic clinical and radiographic findings by three independent observers. Frequencies of each class and subclass were assessed. Intraobserver and interobserver reliabilities were analyzed with Cohen's Kappa and Fleiss' kappa, respectively.Results:Mean sample age was 54.4, 38% was male and 62% were female. 1ABC (25.4%) was most common subclass followed by 1AC (8.7%) and 1ABCD (6.9%). Only small percentage of patients had isolated deformity. Class A was the most frequent component (89.5%), followed by C in 86.2% of the cases. Moderate interobserver reliability (Fleiss` Kappa=0.561, p<0.001, 95% CI 0.528-0.594) was found for overall classification. Very good intraobserver reliability was found (Cohen`s Kappa=0.851, P<0.001, 95% CI 0.777-0.926).Conclusion:Predominantly, 49.3% of patients had a presentation dominantly involving the hindfoot (A) with various combinations of midfoot and/or forefoot deformity (B), (C) with or without subtalar joint involvement (D). Despite limitations due to inherent subjectivity which may account for moderate interobserver agreement, the new system may potentially cover all possible combinations of the PCFD, providing a comprehensive description and guiding treatment in a systematic and individualized manner.

Diagnostic Accuracy of the Progressive Collapsing Foot Deformity (PCFD) Classification.

A consensus group recently proposed the term progressive collapsing foot deformity (PCFD) and a new classification with 2 stages plus 5 classes to describe the complex array of flatfoot deformities. This study aimed to validate different diagnostic accuracy rates of the PCFD classification. This was a survey-based study distributed among 13 foot and ankle fellowship programs for 3 groups of participants with varied experience in practice (group 1: fellows in training, group 2: surgeons in practice for 1-4 years, and group 3: surgeons in practice for ≥5 years). Each participant was asked to assign 20 different cases of flatfoot deformity to the appropriate classes and stages using the PCFD classification. The overall diagnostic accuracy, class, and stage diagnostic accuracy rates for the 20 cases were calculated first for the entire cohort and then compared among the 3 groups. The misdiagnosis rate for each class of deformity (the sum of overdiagnosis and underdiagnosis rates) of the entire cohort was calculated and compared with the other classes. Mean and standard evidence were used to describe numerical data. One-way analysis of variance was used to compare values among the 3 groups and the 5 classes. P <.05 was considered statistically significant. For the whole cohort, the overall diagnostic accuracy, class diagnostic accuracy, and stage diagnostic accuracy rates were 71.0%, 78.3%, and 81.7%, respectively There was a statistically significant difference between group 1 and 2, and group 1 and 3, in overall diagnostic accuracy and class diagnostic accuracy, with no significant difference among the 3 groups regarding stage diagnostic accuracy. Class B had a significantly higher overdiagnosis rate than the rest of the classes, whereas class D was significantly underdiagnosed than others. The misdiagnosis rates for classes A to E were 3.3%, 17.5%, 11.1%, 26.0%, and 3.7%, respectively. The PCFD classification showed overall fair diagnostic accuracy rates. The highest diagnostic accuracy was for "hindfoot valgus deformity" and "ankle instability." Further content validation of the PCFD classification is needed to examine the terminology and interpretation of those classes with low diagnostic accuracy including "midfoot/forefoot abduction deformity," "forefoot varus deformity/medial column instability," and "peritalar subluxation/dislocation."Level of Evidence: Level II, prospective comparative study.

Does tibialis posterior dysfunction correlate with a worse radiographic overall alignment in progressive collapsing foot deformity? A retrospective study

BackgroundPosterior Tibial Tendon (PTT) dysfunction is considered to have an important role in Progressive Collapsing Foot Deformity (PCFD). The objective of our study was to assess the relationship between PTT status and three-dimensional foot deformity in PCFD. MethodsRecords from 25 patients with PCFD were included for analysis. The PTT was considered deficient in patients with a positive single heel rise test or a deficit in inversion strength. Three-dimensional foot deformity was assessed using the Foot and Ankle Offset (FAO) from Weight-Bearing-CT imaging. Hindfoot valgus, midfoot abduction and medial longitudinal arch collapse were assessed on X-Rays using hindfoot moment arm, talonavicular coverage angle and Meary’s angle respectively. Deland and Rosenberg MRI classifications were used to classify PTT degeneration. ResultsPCFD with PTT deficit (13/25) had a mean FAO of 7.75 + /− 3.8% whereas PCFD without PTT deficit had a mean FAO of 6.68 + /− 3.9% (p = 0.49). No significant difference was found between these groups on the hindfoot moment arm and the talonavicular coverage angle (respectively p = 0.54 and 0.32), whereas the Meary’s angle was significantly higher in case of PCFD with PTT deficit (p = 0.037). No significant association was found between PTT degeneration on MRI and FAO. ConclusionPCFD associated three-dimensional deformity, hindfoot valgus and midfoot abduction were not associated with PTT dysfunction. PTT dysfunction was only associated with a worse medial longitudinal arch collapse in our study. Considering our results, it does not appear that PTT is the main contributor to PCFD.Level of Evidence: Level III, Retrospective Comparative Study

Diagnostic accuracy of measurements in progressive collapsing foot deformity using weight bearing computed tomography: A matched case-control study

BackgroundWe aimed to investigate the diagnostic accuracy of known two-dimensional (2D) and three-dimensional (3D) measurements for Progressive Collapsing Foot Deformity (PCFD) in weight-bearing computed tomography (WBCT). We hypothesized that 3D biometrics would have better specificity and sensitivity for PCFD diagnosis than 2D measurements. MethodsThis was a retrospective case-control study, including 28 PCFD feet and 28 controls matched for age, sex and Body Mass Index. Two-dimensional measurements included: axial and sagittal talus-first metatarsal angles (TM1A and TM1S), talonavicular coverage angle (TNCA), forefoot arch angle (FFAA), middle facet incongruence angle (MF°) and uncoverage percentage (MF%). The 3D Foot Ankle Offset (FAO) was obtained using dedicated semi-automatic software. Intra and interobserver reliabilities were assessed. Receiver Operating Characteristic (ROC) curves were calculated to determine diagnostic accuracy (Area Under the Curve (AUC)), sensitivity and specificity. ResultsIn PCFD, mean MF% and MF° were respectively 47.2% ± 15.4 and 13.3° ± 5.3 compared with 13.5% ± 8.7 and 5.6° ± 2.9 in controls (p < 0.001). The FAO was 8.1% ± 3.8 in PCFD and 1.4% ± 1.7 in controls (p < 0.001). AUCs were 0.99 (95%CI, 0.98–1) for MF%, 0.96 (95%CI, 0.9–1) for FAO, 0.90 (95%CI, 0.81–0.98) for MF°. For MF%, a threshold value equal or greater than 28.7% had a sensitivity of 100% and specificity of 92.8%. Conversely, a FAO value equal or greater than 4.6% had a specificity of 100% and a sensitivity of 89.2%. All other 2D measurements were significantly different in PCFD and controls (p < 0.001). ConclusionsMF% and FAO were both accurate measurements for PCFD. MF% demonstrated slightly better specificity. FAO better sensitivity. A combination of threshold values of 28.7% for MF% and 4.6% for FAO yielded 100% sensitivity and specificity.

Do Custom Orthotics Help Improve Pain and Function in Patients with Progressive Collapsing Foot Deformity

Category:HindfootIntroduction/Purpose:Progressive collapsing foot deformity presents with pain, deformity and functional limitations affecting quality of life. The prevalence of this condition ranges from 3-10% depending on the age and sex of the patient. Sixty percent of patients have concurrent medical problems that may delay or limit the ability to undergo surgical intervention. Non-operative treatments such as ankle bracing or custom orthotics are costly and their value to improve pain and function has not been examined with validated patient-centered instruments, specifically patient reported outcome measures. The purpose of this study was to assess if use of a modified UCBL orthosis improved PROMIS pain interference (PI) and physical function (PF) in patients with progressive collapsing foot deformity (PCFD).Methods:Prospective PROMIS data (PF, PI) was obtained from 2015 to 2020 for all patients who obtained a modified UCBL orthosis for PCFD. Patients with PROMIS data pre- and post-obtaining an orthotic with a minimal follow up of 90 days were included. Patients who elected to pursue operative treatment after receiving the orthotic were noted using CPT codes. Patients without complete evaluations were excluded (Figure 1). The primary outcome was PROMIS Scores (PF and PI) before and after orthotic usage. Covariate analysis included patient demographics including age, gender, marital status, race and ethnicity, and orthotic laterality. We estimated separate mixed effects linear regression models with patient random effects for each PROMIS outcome.Results:There were 282 patients included in our cohort with an average age of 57 years. 61% were female and 87.8% were White. Patients had an average follow-up of 467 days +/- 366. Multivariate analysis indicates that there was a 0.94 decrease in PROMIS PF t-score relative to orthotic usage at final follow up (p = 0.035 +/- 7.47) with an increase of 0.76 PROMIS PI t-score (p value = 0.085 +/- 7.40). Despite limited measureable impact on PROMIS outcomes using custom orthotics, only eleven patients subsequently pursued surgery and underwent operative fixation at an average of 461 days after initial evaluation. There were no differences in regard to race, ethnicity or orthotic laterality and PROMIS scores.Conclusion:Publications have focused on outcomes of operative treatment for FCFD, with few examining orthotics. Our study demonstrates a lack of pain and functional improvement with a modified UCBL questioning the potential value of this costly item. However, despite this only 3.9% of patients subsequently underwent surgery. This work raises additional questions: 'What does the patient hope to improve with treatment?' 'What is the role of risk assessment in patients considering treatment choices?' Patient reported outcomes can be used in shared decision making, not only to align expectations, but also when allocating healthcare dollars to durable medical goods.

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.

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.

Plantar Plating for Medial Naviculocuneiform Arthrodesis in Progressive Collapsing Foot Deformity.

Background:Medial column procedures are commonly used to treat progressive collapsing foot deformity (PCFD) reconstruction. The aim of this research is to present the clinical results of plantar plating for medial naviculocuneiform (NC) arthrodesis when NC joint pathology contributes to medial arch collapse. The authors hypothesized that lag screws with a plantar neutralization plate would result in a satisfactory NC joint fusion rate.Methods:A single-surgeon, retrospective case series was performed on patients with flexible PCFD who underwent NC arthrodesis using lag screws and a contoured neutralization plate applied plantarly across the medial NC joint as part of PCFD reconstruction. Thirteen patients (11 females, 2 males; mean age 53.1 [34-62] years) between 2016 and 2019 were identified for inclusion. Mean follow-up was 25.2 ± 12.7 months. Preoperative and postoperative anteroposterior talo–first metatarsal angle, lateral talo–first metatarsal angle, talonavicular coverage angle, and calcaneal pitch were measured. Union was evaluated radiologically. AOFAS midfoot scores were recorded at final follow-up.Results:All parameters demonstrated a significant improvement. Fusion was confirmed in 11 of 13 patients (85%) at a mean 5.7 ± 2.1 months. One patient required a revision of their NC fusion because of symptomatic nonunion. There were no cases of symptomatic plantar hardware.Conclusion:The results of this small cohort series suggest that lag screw with plantar plate NC arthrodesis yielded generally improved short-term radiographic and clinical outcomes in PCFD patients with medial arch collapse through the NC joint.Level of Evidence: Level IV, retrospective case series.

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.

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.

Lag Screw with Plantar Plating for Naviculocuneiform Arthrodesis in Progressive Collapsing Foot Deformity

Category:Midfoot/ForefootIntroduction/Purpose:Medial column procedures are a common adjunct to progressive collapsing foot deformity (PCFD) correction. In particular, naviculocuneiform (NC) arthrodesis could be performed when degeneration or instability at the NC joint is contributing to arch collapse. Plantar plate fusion resists gapping along the tension side of the joint, potentially reducing risk of non-union and recurrent deformity. Additionally, by placing the hardware in a plantar location there is an increased soft tissue envelope to function in a protective matter and eliminate the possibility of hardware prominence and tendon irritation. The purpose of this study was to analyze short-term clinical and radiographic outcomes of NC fusion using a lag screw with plantar plating technique.Methods:A single-surgeon retrospective case series was performed on patients with PCFD and medial arch collapse treated with NC arthrodesis using a lag screw plus plantar plating technique between January 2016 and December 2019, with a minimum six month clinical and radiographic follow up. Patients undergoing revision NC joint arthrodesis, patients with incomplete imaging, or an arthrodesis technique that did not utilize NC joint plantar plating were excluded. Demographic data, perioperative data, complications, and reoperations were recorded from electronic medical records. Pre-operative AOFAS midfoot scores were calculated at the initial clinic visit and then again at the patients' most recent follow-up. In the case of most recent follow up occurring prior to six months post-operatively, a telemedicine visit was performed. Anteroposterior (AP) and lateral talo-first metatarsal angles, talonavicular coverage angle, and calcaneal pitch were measured independently by three authors. Fusion was confirmed radiographically and computed topography when union was in question.Results:Nineteen patients (15 female, 4 male; 11 right, 8 left) with a mean age of 56.6 years and a mean follow-up of 21.0 +- 13.4 months were reviewed. A mean 3.4 concomitant procedures were performed at the time of NC fusion. AP talo-first metatarsal angle (18.9° to 5.2°), lateral talo-first metatarsal angel (-18.7° to -4.4°), talonavicular coverage angle (28.1° to 7.4°), and calcaneal pitch (14.6° to 20.1°) all improved significantly (p<0.001). Fusion was confirmed in 15 (79%) patients at a mean 6.1 +- 3.5 months. Mean AOFAS midfoot scores improved from 51.7 +- 13.0 preoperatively to 82.6 +-12.8 (p<0.001) at an average 21.0 +- 13.4 months follow up. Two patients experienced broken hardware, one patient fractured through flexor digitorum longus (FDL) transfer site and experienced non-union requiring revision at 9.5 months, one patient experienced symptomatic lateral column hardware requiring removal, and one patient experienced non-union requiring revision at 13.5 months.Conclusion:Lag screw with plantar plating is a technique for NC arthrodesis that is associated with a higher non-union rate (21%) than what is reported in the literature. Nonetheless, at short term (mean 21 months) follow up, the technique proved capable of correcting medial arch collapse through the NC joint when used in conjunction with adjunctive soft tissue and bony procedures. Plantar plating technique resulted in no instances of symptomatic hardware along the medial midfoot. Addressing medial arch collapse with NC arthrodesis resulted in significant improvement of both radiographic outcomes and patient reported clinical outcomes.

High Reliability for Weightbearing CT Based Automated 3D Measurements to Assess Progressive Collapsing Foot Deformity

Category:Hindfoot; Midfoot/Forefoot; OtherIntroduction/Purpose:In progressive collapsing foot deformity (PCFD), hind- and midfoot deformities are paramount. However, an accurate assessment thereof, using weightbearing radiography, remains challenging. Automated three-dimensional (3D) measurements derived from weightbearing computed tomography (WBCT) scans may provide a more accurate approach for deformity assessment. In this study, automated 3D measurements based on WBCT were compared to two-dimensional (2D) measurements performed on weightbearing radiographs. Furthermore, it was investigated whether various stages of PCFD could be identified using automated 3D measurements.Methods:Twenty patients treated at our institution with either a flexible (N=10) or rigid (N=10) PCFD were identified, retrospectively analyzed and compared to a control group of thirty healthy individuals. Four angles and two distances measured on weightbearing radiographs were compared to the automated 3D measurements derived from WBCT scans.Results:In 5 out of 6 variables, the reliability of the measurements derived from weightbearing radiographs was lower than the automated measurements that derived from WBCT scans. The automated 3D measurements showed: the talar tilt in the ankle mortise was more valgus in patients with a rigid PCFD when compared to patients with a flexible PCFD; medial facet subluxation was present in all but one patient; patients with a sinus tarsi impingement evidenced a higher overlap between the talus and calcaneus (12.4+-2.6 mm) compared to patients without impingement (7.8+-3.9 mm; P=0.020).Conclusion:A higher reliability of automated 3D measurements derived from WBCT scans, was evident for most variables when compared to measurements based on weightbearing radiographs. Besides being less prone to errors, automated 3D measurements may provide more reliable information regarding the hind- and midfoot alignment in patients with PCFD. Future studies may show to what extent 3D measurements could contribute to current diagnostic algorithms and treatment concepts of patients with PCFD.

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.