Search

Introduction/Purpose: Weightbearing computed tomography (WBCT) is a reliable and precise modality for the measurement and analysis of bone position in the foot and ankle, as well as associated deformities. WBCT to assess three dimensional relationships among bones allowed the development of new measurements, as the Foot and Ankle Offset (FAO), which has high inter-rater and intra-rater reliability. This study reports our institution's experience utilizing WBCT for the care of foot and ankle patients by describing its utility across different orthopedic diseases in improving diagnostic assessment, aiding surgical planning, and expanding the use for objective clinical follow-up. Methods: The medical records of consecutive patients with various foot and ankle disorders that underwent WBCT examination as part of the standard of care at a single institution between November 2014 and August 2020 were retrospectively reviewed. Patient factors, including body mass index (BMI), sex, and patient comorbidities were collected. 3D coordinates for calculation of FAO were harvested using the Multiplanar Reconstruction (MPR) views were calculated from the obtained exams. Descriptive statistics were performed with Shapiro-Wilk test and the Anderson-Darling tests. Results: 1175 feet and ankles (820 patients) had a WBCT performed over the studied 68 months. 53% of the subjects were male and 47% female. 588 of the acquisitions were from the right side (50.04%) and 587 from the left side (49.96%). Diabetes was present in 15.47% of, Rheumatic diagnoses in 4.52% and smoking habits in 44.10% of patients. Mean BMI of the sample was found to be 32.47 (32.03-32.90, 95% CI). The mean Foot and Ankle Offset (FAO) encountered in the study's population was 2.43 (2.05-2.82, 95% CI; min -30.8, max 37.65; median 2.39). Conclusion: This study contains the largest cohort of WBCTs with accompanied FAO measurements to date, which can aid with establishing a new baseline FAO measurement for multiple pathological conditions. Acquiring WBCTs resulted in more specific diagnoses for patients with foot and ankle complaints. The ability to utilize WBCT for presurgical planning, its capability to provide a 3D reconstruction of patient anatomy, and use for assessment of advanced relational foot and ankle measurements, like FAO, demonstrate how WBCT may serve as a remarkable utility in clinical practice and has become a standard of care in our practice at the University of Iowa. [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Identifying markers of severity and progression in Progressive Collapsing Foot Deformity (PCFD) provides surgeons with critical information, possibly aiding in the decision making along the treatment algorithm. Subtalar middle facet subluxation (MFS), the percent undercoverage of the talus in relation to its calcaneus counterpart, was recognized as a reliable marker in weight-bearing computerized tomography (WBCT) for PCFD diagnosis. The Foot and Ankle Offset (FAO), the relative position between the center of the ankle joint and the foot tripod, is a three-dimensional WBCT tool predictive of disease severity. Our objective is to assess the relationship between the amount of MFS and FAO in flexible PCFD patients. We hypothesize that MFS is a reliable assessment of disease severity and correlates with FAO. Methods: In this retrospective IRB-approved comparative study, a total of 56 individuals with PCFD (74 feet) who underwent WBCT for baseline assessment were analyzed. Two blinded fellowship-trained foot and ankle surgeons performed the measurements. MFS was executed in the coronal-plane, at the midpoint (on sagittal-plane) of the middle facet (see attached figure). Dedicated software was utilized to perform the FAO, using the most plantar voxels of the first metatarsal, fifth metatarsal, calcaneal tuberosity and centre of the ankle. Interobserver agreement was quantified for MFS and FAO using intraclass correlation coefficient (ICC). Intermethod agreement between MFS and FAO was assessed by Spearman's correlation. Bivariate linear regression analysis was used to assess the relationship between MFS and FAO. A partition prediction model and multivariate analysis were utilized to assess influence of MFS measurements on FAO values and vice versa. Results: A total of 56 patients (74 feet) were included in the study. The ICCs for interobserver reliability was 0.87 for MFS and 0.95 for FAO. In a bivariate analysis, MFS and FAO were found to be significantly and linearly correlated (P< 0.0001, R2 0.26). Foot Angle Offset = 2.22 + 0.12*Medial Facet Subluxation (%). In multivariate analysis, FAO and body mass index (BMI) were significantly correlated with MFS (<0.001 and 0.02, respectively). The partition prediction model demonstrated that an MFS of 27.5% was an important threshold for increased FAO, with FAO of 3.4% +-2.4% when MFS was below threshold and 8.0% +-3.5% when above threshold. Conclusion: We found a positive linear correlation between MFS and FAO measurements. An MFS of 27.5% was an important threshold for higher FAO values, which corresponded to a worst overall alignment. Our results are consistent with the idea that MFS is a reliable marker for PCFD diagnoses and severity, correlating well with the FAO. This data may support clinical decisions in PCFD patients. Also, BMI was found to be positively correlated with MFS. Future prospective and longitudinal studies are needed to confirm the findings of this study. [ABSTRACT FROM AUTHOR]

Introduction/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. [ABSTRACT FROM AUTHOR]

Introduction/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. [ABSTRACT FROM AUTHOR]