Adult Acquired Flatfoot Deformity: Anatomy, Biomechanics, Staging, and Imaging Findings

Assessing postural stability in flatfoot using a time-in-boundary method during single-leg standing

Flatfoot, a foot deformity characterized by the collapse of the arch, significantly impacts an individual's balance and stability. This study explored postural adjustments and sway excursions in individuals with and without flatfoot using the Time-in-Boundary method. This method assessed relative stability by exploring various center of pressure radius thresholds during three trials of single-leg stance. We observed significant interactions in threshold levels (F = 4.37, p = 0.04) and normalized relative stable times (F = 7.64, p = 0.01), particularly in the initial trials. Initially, the flatfoot group showed marked decreases in stable times at 10 mm, 15 mm, and 20 mm thresholds, which expanded to 25 mm and 30 mm in subsequent trials. Despite a significant decrease in stability at the 30 mm threshold in early trials, participants exhibited improved stability control as trials progressed. This enhancement likely reflects a combination of a learning effect and an increased understanding of the task requirements, underscoring the adaptability of postural control systems to the biomechanical challenges posed by flatfoot. The Time-in-Boundary method has proven to be an effective tool for clinicians to assess postural control, playing a vital role in developing customized rehabilitation strategies for individuals with flatfoot.

Biomechanical effect between conventional and 3-dimensional printed customized foot orthoses on medial longitudinal arch support and rearfoot angle in adults with flexible flatfeet

BACKGROUND

Customized foot orthoses are used to treat flexible flatfoot regarding medial longitudinal arch (MLA) support, alignment correction, and pain management. Recently, 3-dimensional (3D) printing orthosis has become the focus of discussion regarding function and manufacturing. We aimed to investigate differences in biomechanical effects between flat insole (Flat), conventional foot orthosis (Cinsole), and 3D printed foot orthosis (3Dinsole) use on MLA support and rearfoot alignment during walking in adult flexible flatfeet.

METHODS

Twelve men with flexible flatfoot were recruited. Data were collected and analyzed using a Vicon motion capture system under 3 trial conditions: Flat and >1 month after using Cinsole and 3Dinsole. Repeated-measures analysis of variance with Bonferroni post hoc tests was used to compare kinematics variables, foot pain, and satisfaction.

RESULT

Dynamic navicular drop significantly reduced with the use of the Cinsole and 3Dinsole compared with Flat ( P < 0.001; ηp 2 = 0.65). The maximum rearfoot eversion angle with the use of the Cinsole and 3Dinsole significantly reduced from Flat ( P < 0.001; ηp 2 = 0.56). Foot pain score significantly decreased after using foot orthoses; satisfaction between Cinsole and 3Dinsole was not significantly different.

CONCLUSIONS

Thus, Cinsole and 3Dinsole are effective alternative treatments of MLA support and rearfoot alignment in adults with flexible flatfoot. 3D printing is a future technology with potential to replace conventional production methods. However, material characteristics, design, and manufacturing process can affect treatment outcomes; hence, our results may not represent all variations of 3D printed foot orthoses.

Two-Dimensional and 3-Dimensional MRI Assessment of Progressive Collapsing Foot Deformity-Adult Acquired Flat Foot Deformity

This article is meant to serve as a reference for radiologists, orthopedic surgeons, and other physicians to enhance their understanding of progressive collapsing foot deformity, also known as adult acquired flat foot deformity. Pathophysiology, imaging findings, especially on MRI and 3-dimensional MRI are discussed with relevant illustrations so that the readers can apply these principles in their practice for better patient managements.

Hazard of Failed Nonoperative Management for Symptomatic Accessory Navicular in Children and Adolescents: A Population-Based Case-Cohort Study

BACKGROUND

The accessory navicular (AN) is an idiopathic condition of the foot present in 4% to 21% of the population. Most ANs remain asymptomatic, but children and adolescents who develop symptoms can have remarkably reduced quality of life. Although many respond to conservative measures, surgery is occasionally needed. Our purpose was to determine factors associated with the failure of nonoperative management.

METHODS

This single-institution retrospective case-cohort study included patients up to age 19 years presenting between 2000 and 2021 with symptomatic AN and treated with standard-of-care. All 298 surgical cases, indicating failed nonoperative treatment, were included. For the subcohort, 299 patients were randomly sampled from all eligible patients, regardless of treatment. Baseline characteristics were summarized for the surgical cases and subcohort. Proportional hazards assumptions were checked and stratification implemented when necessary. Marginal structural proportional hazard modeling was used to estimate hazard ratios with 95% confidence intervals via inverse probability and LinYing weighting methods.

RESULTS

The 298 surgical cases failed nonoperative management at a median of 5.2 months (IQR, 2.0-11.6 mo). In the subcohort, 86 failures of nonoperative management and 213 nonfailures constituted a 28.8% surgery rate. In both cohorts, nearly all patients played sports. Univariate proportional hazard modeling found older age ( P =0.02) and activity limitation ( P <0.001) at presentation, female sex ( P =0.002), higher BMI ( P =0.01), AN on the right ( P <0.001), and bone marrow edema of the AN ( P <0.001) and navicular body ( P <0.001) on MRI were associated with increased hazard of nonoperative failure. Nearly all of the surgical cohort reported improvement in pain (278/296, 94%) and returned to their primary sport (236/253, 93%) after surgery. Most also experienced full resolution of symptoms (187/281, 67%).

CONCLUSIONS

Symptomatic AN predominantly affects female athletes, leading to surgery in 28.8% of our subcohort. Conservative treatment may be less successful-and therefore surgery could be more strongly considered-in older age, activity limitation at presentation, female sex, higher BMI, right-sided AN, and bone marrow edema on MRI. Surgery is effective for symptomatic and functional improvement.

LEVEL OF EVIDENCE

Case-cohort-Level III.

Hallux valgus and pes planus: Correlation analysis using deep learning-assisted radiographic angle measurements

BACKGROUND

The relationship between hallux valgus (HV) and pes planus remains unresolved. This study aims to determine the correlation between HV and pes planus using a deep learning (DL) model to measure radiographic angle parameters.

METHODS

In total, radiographs of 212 feet detectable by the DL model were analyzed. HV was evaluated using the hallux valgus and intermetatarsal angles, while pes planus was assessed using the lateral talo-first metatarsal (Meary's) and calcaneal pitch angles. Correlation analyses were performed for each DL model-measured angle parameter. We investigated whether pes planus worsened with increasing severity of HV and vice versa.

RESULTS

All parameters were significantly correlated with each other. Pes planus worsened with increasing severity of HV, and as the severity of pes planus increased, HV also worsened.

CONCLUSION

Utilizing the DL model-assisted radiographic angle measurements, this study established a significant correlation between HV and pes planus.

LEVEL OF EVIDENCE

III.

Comparing the efficacy of exercise therapy on adult flexible flatfoot individuals through a network meta-analysis of randomized controlled trials

The aim of this study is to compare the efficacy of different exercise interventions for adult flexible flatfoot. Nine databases (PubMed, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials (CENTRAL), SCOPUS, PRDro, Google Scholar, China National Knowledge Infrastructure(CNKI) and Wanfang data) were systematically searched from their inception until February 2024. The search resulted in 2112 records, with 11 studies included. All networks revealed low heterogeneity and non-significant inconsistency (I2 ≤ 25.0%). Three network plots were formed for navicular drop. Firstly, compared with the control group, strengthening the posterior tibial muscle + stretching the iliopsoas muscle + TCE (MD: 3.32, 95% CI: 1.78, 4.89), PNF (MD: 1.81, 95%CI: -0.05, 3.70), SFE (MD: 1.23, 95%CI: 1.02, 1.44) all showed better effects. And strengthening the posterior tibial muscle + stretching the iliopsoas muscle + TCE exercise is considered to be the most effective intervention, with SUCRA of 0.97. Secondly, compared with the control group, hip-focused neuromuscular exercise (MD: 6.22, 95% CI: -1.69, 14.12), SFE with EMG biofeedback (MD: -0.81, 95%CI: -1.59, 3.21) all showed better effects. And hip-focused neuromuscular exercise is considered to be the most effective intervention, with SUCRA of 0.92. Thirdly, the internal foot muscle training combined with gluteus muscle strengthening is significantly better than the other two groups, with SUCRA of 0.99. For the foot posture index, comprehensive reinforcement (MD: 1.95, 95% CI - 0.19, 4.03) showed better effects compared with the control group. In the probability ranking table, comprehensive reinforcement is significantly better than the other two groups, with SUCRA of 0.98. For the foot function index, orthoses wear + stretching + eccentric progressive resistive exercise of tibialis posterior is significantly better than the other two groups, with SUCRA of 0.92. In conclusion, various exercise therapies improve the arch shape and function of patients with flexible flatfoot, particularly hip muscle and lower limb overall muscle training.

Correlation of progressive collapsing foot deformity with varus knee alignment in young adults - A case control study

Background

Majority of patients with Progressive Collapsing Foot Deformity(PCFD) have symptoms pertaining to the knee. Malalignment at the foot will have effects on the alignment of the knee. In this case control study, we compare the alignment of the knees between patients with PCFD and controls.

Materials

Sixty subjects, 30 PCFD and 30 controls, underwent radiographs in which the tibiofemoral angle and radiological parameters of PCFD were assessed. Parameters of PCFD were correlated with the tibiofemoral angle.

Results

Mean tibiofemoral angle was 3.8° among the cases and 4.8° among the controls which was statistically significant(P = 0.001). Varus knee alignment was seen in 41 out of 60 limbs with PCFD which was statistically significant(P < 0.001). The tibiofemoral angle correlated significantly with the Meary angle(P = 0.03) and the talonavicular coverage angle(P = 0.003).

Conclusions

PCFD is associated with varus knee malalignment. This varus deformity early in adulthood may lead to deleterious effects like medial compartment osteoarthritis in later life. Early intervention for such patients may help avoid this knee damage.

Level of evidence

Level 3-prognostic.

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

BACKGROUND

Flatfoot is a condition resulting from complex three-dimensional (3D) morphological changes. Most Previous studies have been constrained by using two-dimensional radiographs and non-weight-bearing conditions. The deformity in flatfoot is associated with the 3D morphology of the bone. These morphological changes affect the force line conduction of the hindfoot/midfoot/forefoot, leading to further morphological alterations. Given that a two-dimensional plane axis overlooks the 3D structural information, it is essential to measure the 3D model of the entire foot in conjunction with the definition under the standing position. This study aims to analyze the morphological changes in flatfoot using 3D measurements from weight-bearing CT (WBCT).

METHOD

In this retrospective comparative our CT database was searched between 4-2021 and 3-2022. Following inclusion criteria were used: Patients were required to exhibit clinical symptoms suggestive of flatfoot, including painful swelling of the medial plantar area or abnormal gait, corroborated by clinical examination and confirmatory radiological findings on CT or MRI. Healthy participants were required to be free of any foot diseases or conditions affecting lower limb movement. After applying the exclusion criteria (Flatfoot with other foot diseases), CT scans (mean age = 20.9375, SD = 16.1) confirmed eligible for further analysis. The distance, angle in sagittal/transverse/coronal planes, and volume of the two groups were compared on reconstructed 3D models using the t-test. Logistic regression was used to identify flatfoot risk factors, which were then analyzed using receiver operating characteristic curves and nomogram.

RESULT

The flatfoot group exhibited significantly lower values for calcaneofibular distance (p = 0.001), sagittal and transverse calcaneal inclination angle (p < 0.001), medial column height (p < 0.001), sagittal talonavicular coverage angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.015) Hibb angle. In contrast, the sagittal lateral talocalcaneal angle (p = 0.013), sagittal (p < 0.001) and transverse (p = 0.004) talocalcaneal angle, transverse talonavicular coverage angle (p < 0.001), coronal Hibb angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.001) Meary's angle were significantly higher in the flatfoot group. The sagittal Hibb angle (B =  - 0.379, OR = 0.684) and medial column height (B =  - 0.990, OR = 0.372) were identified as significant risk factors for acquiring a flatfoot.

CONCLUSION

The findings validate the 3D spatial position alterations in flatfoot. These include the abduction of the forefoot and prolapse of the first metatarsal proximal, the arch collapsed, subluxation of the talonavicular joint in the midfoot, adduction and valgus of the calcaneus, adduction and plantar ward movement of the talus in the hindfoot, along with the first metatarsal's abduction and dorsiflexion in the forefoot.

Deep learning-based automated angle measurement for flatfoot diagnosis in weight-bearing lateral radiographs

This study aimed to develop and evaluate a deep learning-based system for the automatic measurement of angles (specifically, Meary's angle and calcaneal pitch) in weight-bearing lateral radiographs of the foot for flatfoot diagnosis. We utilized 3960 lateral radiographs, either from the left or right foot, sourced from a pool of 4000 patients to construct and evaluate a deep learning-based model. These radiographs were captured between June and November 2021, and patients who had undergone total ankle replacement surgery or ankle arthrodesis surgery were excluded. Various methods, including correlation analysis, Bland-Altman plots, and paired T-tests, were employed to assess the concordance between the angles automatically measured using the system and those assessed by clinical experts. The evaluation dataset comprised 150 weight-bearing radiographs from 150 patients. In all test cases, the angles automatically computed using the deep learning-based system were in good agreement with the reference standards (Meary's angle: Pearson correlation coefficient (PCC) = 0.964, intraclass correlation coefficient (ICC) = 0.963, concordance correlation coefficient (CCC) = 0.963, p-value = 0.632, mean absolute error (MAE) = 1.59°; calcaneal pitch: PCC = 0.988, ICC = 0.987, CCC = 0.987, p-value = 0.055, MAE = 0.63°). The average time required for angle measurement using only the CPU to execute the deep learning-based system was 11 ± 1 s. The deep learning-based automatic angle measurement system, a tool for diagnosing flatfoot, demonstrated comparable accuracy and reliability with the results obtained by medical professionals for patients without internal fixation devices.

Electromyographic Analysis of Large Muscle Activity in Progressive Collapsing Foot Deformity

BACKGROUND

There are various deformities described in the spectrum of Progressive Collapsing Foot Deformity (PCFD) which not only have adverse effects on the foot but also on the entire lower limb. Early lower limb muscular fatigue and pain during exertion is the most common complaint of patients with PCFD. Surface electromyography (sEMG) provides an accurate assessment of muscle activity. In this study, we aim to compare the activities of quadriceps, hamstrings, and gastrosoleus muscle groups of adult patients with PCFD with normal lower limbs and correlate the radiological parameters and functional effects of PCFD with the activities.

METHODS

Thirty patients with bilateral PCFD and 30 controls underwent weight-bearing anteroposterior (AP), lateral, and hindfoot alignment radiographs of the foot. Radiographic parameters of PCFD were assessed. Surface electromyography was used to assess the quadriceps, hamstrings, and gastrosoleus activities, and this was compared between the 2 groups and correlated with radiological measurements of PCFD. Tegner activity questionnaire was used to assess the functional effects of collapsed arch.

RESULTS

Electrical activities of all muscle groups were significantly higher in cases than controls. Meary's angle and hindfoot moment arm had significant correlations with hamstring activity (P = .013) and gastrosoleus activity (P = .027), respectively. Tegner scores of cases were significantly lower than those of controls (P = .041).

CONCLUSIONS

The PCFD causes an increase in activity of large muscles of the affected lower limb which act on joints other than those in the foot. This finding may be due to several compensatory mechanisms that counteract the deforming forces. This may be a cause for the frequent complaint, early fatigue, and hence functional impairment. However, most radiological parameters did not correlate with muscle activities and larger study size may be required for further association.

LEVELS OF EVIDENCE

Diagnostic: Level 3.

Effect of orthopedic insoles on lower limb motion kinematics and kinetics in adults with flat foot: a systematic review

Flatfoot is characterized by the collapse of the medial longitudinal arch, eversion of the rearfoot and abduction of the loaded forefoot. Orthopedic insoles are the frequently recommended treatment to support the arch of the foot, adjust the structure of the foot, reduce pain, improve stability and new techniques have been applied to the design of orthopedic insoles in recent years. However, the effectiveness of orthopedic insoles in different motions is still debated from the perspective of biomechanics. Therefore, this study aimed to explore the impact of orthopedic insoles on the kinematics and kinetics of lower limb motion, and to verify effectiveness and propose possible future research directions. We conducted a literature search across three databases employing Boolean operations and filtered results based on eligibility criteria. A total of 671 relevant literature were searched in this review, and 19 literature meeting the requirements were finally included. The results showed that: 1) orthopedic insoles were effective when patients walk, run and jump from the perspective of biomechanics; 2) orthopedic insoles had different result on the change of ankle sagittal angle, moment and peak pressure in the metatarsal region; 3) Whether the effect of insoles, which uses new techniques such as different 3D printed technologies and adds various accessories, can be further improved remains to be further studied; 4) Follow-up studies can pay more attention to the differences between diverse populations, increase the breadth of running and jumping and other movements research and long-term intervention.

Comparative study of the effects of custom-made insole and ordinary insole in adults with flexible flatfoot on different slopes

BACKGROUND

Flatfoot (pes planus) is a common foot deformity, and its causes are mainly related to age, gender, weight, and genetics. Previous studies have shown that custom-made insoles could have a positive effect in improving plantar pressure and symptoms in individuals with flexible flatfeet, but it remains to be explored whether they can still show benefits in daily walking on different slopes.

OBJECTIVE

This study aims to investigate a custom-made insole based on plantar pressure redistribution and to verify its effectiveness by gait analysis on different slopes.

METHODS

We recruited 10 subjects and compared the peak pressure and impulse in each area between custom-made insole (CI) and ordinary insole (OI) groups.

RESULTS

The results illustrate that CI raises the pressure in T area, improves the ability of the subjects to move forward in the slope walking, which was beneficial to gait stability.

CONCLUSION

The redistribution of pressure in MF and MH area is promoted to provide active protection for subjects. Meanwhile, CI could decrease the impulse in MF area during uphill and level walking, which effectively reduces the accumulation of fatigue during gait. Moreover, avoiding downhill walking could be able to protect foot from injury in daily life.

Determining the changes in morphology and loading status following medial displacement calcaneal osteotomy for flatfoot using patient-specific finite element models

Medial displacement calcaneal osteotomy (MDCO) is the standard procedure for flatfoot. We investigated the effect of MDCO on the foot using a finite element analysis. Foot models were created from computed tomography data of 8 patients with flat feet. MDCO was performed on each model with bone translation distance of 4, 8, and 12 mm. The morphological changes, plantar pressures, and stress percentage on the talocrural and subtalar joints were evaluated before and after surgery. Morphological evaluation showed improvement in the medial longitudinal arch. The stress percentage of plantar pressure in the medial area decreased, and the stress percentage of plantar pressure in the mid- and lateral forefoot area increased. At the talocrural joint, the medial and middle stress percentage increased, while the lateral and posterior stress percentage decreased. In the subtalar joint, the stress percentage in the middle subtalar joint increased and that in the posterior subtalar joint decreased. Within the posterior subtalar joint, the anterior and medial stress percentage increased, while the posterior and lateral stress percentage decreased. Preoperative simulation using the finite element analysis may be useful in understanding postoperative morphological changes and loading conditions to perform patient-specific surgery.

Effects of Preoperative Abnormality of Posterior Tibial Tendon on the Surgical Outcomes of Medial Osteochondral Lesion of the Talus

BACKGROUND

Although surgical treatment for osteochondral lesion of the talus (OLT) can obtain good clinical outcomes, the rate of return to sports is variable. It is reported that medial OLT unrelated to trauma has abnormal structures in the medial aspect, which may induce the medial OLT due to the medial instability. The posterior tibial tendon (PTT) plays an important role in the stabilization of the foot, and high mechanical stress may be added to the PTT to compensate for medial instability in medial OLT. We investigated whether abnormal PTT findings on preoperative magnetic resonance imaging (MRI) in patients with OLT affect clinical outcomes after surgery.  Methods: Eighty-one ankles in 74 patients who were treated surgically for OLT were included in this study (41 men and 33 women; mean age, 26.0 years). Abnormalities of the PTT were evaluated using preoperative MRI. The Japanese Society for Surgery of the Foot (JSSF) scale, arch height, and ankle activity score (AAS) on standing plain radiogram were compared between patients with and those without preoperative PTT abnormalities.

RESULTS

Twenty-five ankles (30.9%) had PTT abnormalities on preoperative MRI. All patients with preoperative PTT abnormalities were medial OLT. There were no significant differences in the preoperative JSSF scale in the procedures for OLT. The postoperative JSSF scale and arch height were significantly lower in patients with preoperative PTT abnormalities than those without them. AAS in patients with preoperative abnormalities significantly decreased at the final follow-up.  Conclusion: PTT abnormalities on preoperative MRI may affect clinical outcomes even in preoperative asymptomatic patients in the medial OLT unrelated to trauma.

Knowledge and Attitudes Regarding Flatfoot in the Al-Jouf Region, Saudi Arabia

Background Flatfoot is a syndrome that includes multiple static and dynamic deformities, characterized by the flattening of the medial arch. It is a common disorder that may affect any age group, causing foot malalignment, pain, and loss of function. Community awareness about flatfoot is essential for the prevention and control of flatfoot complications, ultimately improving the quality of life. The current study aimed to assess community knowledge and attitudes about flatfoot in the Al-Jouf region, Saudi Arabia. Methods The study enrolled 315 participants from different sectors of the Saudi population in the Al-Jouf region. An online questionnaire was distributed to them. Answers were scored on a scale of five (never "1", rarely "2", sometimes "3", often "4", always "5"). The level of their knowledge was determined by calculating the scores. Results There were significant disparities in the answers, with the majority of participants denying the effect of flatfoot on walking (135, 42.9%), running (123, 39%), standing for long periods (186, 59%), or causing tripping. More than half of the participants agreed that flatfoot never affects school activities or participation in clubs or activities after school. However, most participants showed a good attitude toward individuals with flatfoot, as they were not bothered by their way of walking (199, 63.2%) or how their foot or ankle looks (255, 80.9%), and never embarrassed them because of their foot or ankle (266, 84.5%). Most participants agreed that no one has the right to be unkind to them because of their foot or ankle (276, 87.5%). These positive attitudes are likely due to the cultural norms of the community. Conclusion There is a decreased level of awareness about the effects of flatfoot on daily physical activities among the Saudi population in the Al-Jouf region. However, their attitude toward people suffering from flatfoot is highly appreciated. Health education programs are recommended.

Chronic Deltoid Insufficiency in Stage IV Adult Acquired Flatfoot Deformity: Do We Have a Good Answer?

Stage IV adult acquired flatfoot deformity (AAFD) with secondary chronic deltoid ligament insufficiency is a challenging deformity to treat, with minimal consensus in the literature concerning its surgical management. Many surgical treatment options have been described, including joint-sparing techniques, fusions, osteotomies, and even arthroplasties. However, questions remain as to what, if any, treatment is optimal. This contribution reviews studies on surgical treatments for stage IV AAFD with deltoid ligament failure and provides a critical analysis regarding the quality of outcomes reported for those different treatment options. PubMed and Google Scholar databases were searched between June 1, 2022, and August 15, 2022, for studies published between 1990 and 2022 that describe the treatment of stage IV AAFD with deltoid ligament insufficiency. Articles included in the study focused on subjects with stage IV AAFD and associated deltoid ligament insufficiency undergoing surgical correction. Exclusion criteria included stage I, II, and III AAFD, as well as deltoid ligament repair following acute injury/rupture. Nine studies covering five different treatment options for patients with stage IV AAFD and chronic deltoid insufficiency were included, with minimal overlap in outcome measures used to assess the efficacy of the procedure. Triple arthrodesis with deltoid ligament reconstruction resulted in a 62.5% (5/8) success rate with a residual tibiotalar (TT) angulation of 2° (success defined as <3°). Tibiotalar arthrodesis of four patients resulted in an average post-operative tibiotalar angulation of 4.8° with all patients showing progressive destabilization of the hindfoot complex at 12-18 year follow-ups. Deltoid arthroscopic laminoplasty (Brostrom) resulted in an increased American Orthopaedic Foot and Ankle Society (AOFAS) score from 49.7 pre-op to 91.9 post-op. There was no long-term follow-up of these patients. Deltoid ligament reconstruction using autografts of the peroneus longus resulted in a post-operative valgus of 2.1° in one study and <5° in another. Deltoid ligament reconstruction using an anterior tibial tendon autograft resulted in a gain of 126.4 + 40.2% in stiffness compared to an intact ligament. Twinfix suture anchors resulted in a post-operative hindfoot angle averaging 5.3°. Combined deltoid and spring ligament reconstruction resulted in a 5.1° valgus angulation. There is currently no standard of care or clinical consensus regarding surgical treatment for stage IV AAFD with deltoid insufficiency. Several studies imply that mild valgus malalignment around the tibiotalar joint can result in satisfactory outcomes. A few studies even deemed <5° of valgus tilt post-operatively successful. However, it has been described that any imbalance in tibiotalar tilt is a significant risk factor for progressive arthritis and future ligamentous failure. No treatment option was able to correct valgus tilt to an anatomical standard (i.e., to normal anatomy). These varied findings, along with the lack of consensus on post-surgical measures to assess efficacy, are worrisome and emphasize the need for better surgical options. Moreover, there is a critical need for additional research on the long-term outcomes following stage IV AAFD and deltoid insufficiency repair, particularly, as over five million people in the United States and 10% of the geriatric population are affected by AAFD with a risk of progressing to stage IV.

Impact of static foot disorders on the conservative treatment success in chronic venous disease patients without wounds

OBJECTIVE

Chronic venous disease (CVD) and static foot disorders (SFDs) are prevalent conditions that commonly cause lower extremity pain. These conditions share common factors such as age and weight in their etiology. This study aimed to investigate the impact of SFDs on the treatment response of patients undergoing conservative treatment for CVD without wounds.

MATERIALS AND METHODS

A retrospective evaluation was conducted on 328 patients (60 males, 268 females) with CVD. Parameters including age, gender, affected side, body mass index, Visual Analog Scale (VAS), Clinical-Etiological-Anatomical-Pathophysiological (CEAP) classification, and revised Venous Clinical Severity Score (rVCSS) were considered for evaluation. Radiological measurements of calcaneal pitch angle (CPA) were analyzed as a determinant of SFDs.

RESULTS

VAS and rVCSS of the patients were evaluated before and after conservative treatment of CVD without concomitant treatment of SFDs. The presence of SFDs was associated with decreased treatment success (P < .001). Among different types of SFDs, the pes cavus group exhibited the lowest change in VAS and rVCSS scores before and after conservative CVD treatment. In contrast, the normal group demonstrated the highest improvement. Patients with a normal foot medial arch consistently achieved the best treatment outcomes compared with patients with other SFDs.

CONCLUSIONS

In conclusion, SFDs affect outcomes of conservative treatment of CVD in CEAP 0 to 3 patients, with the efficacy of treatment dependent upon the severity of SFDs.

Patient Reported Outcomes Following Triple Arthrodesis for Adult Acquired Flat Foot Deformity: Minimum Two Year Follow Up

The aim of this study is to analyze patient-reported outcomes following this procedure as well as any demographics that may confer prognostic capability. A retrospective analysis was conducted of patients who underwent Triple Arthrodesis at our facility from 2014-2021. Patients were selected if they underwent an isolated triple arthrodesis. All cases included either a gastrocnemius recession versus a percutaneous tendo-achilles lengthening depending on the patient's Silverskiold examination. The electronic medical record was utilized to collect basic patient demographics, previous foot and ankle surgeries, hardware failures, additional procedures, and surgical complications. To evaluate outcomes, we compared patient reported outcomes measurement information system (PROMIS) survey scores with the general population and preoperative versus postoperative visual analog scale (VAS) scores. Foot function index (FFI) scores and scores were utilized as a validation tool for our results. A total of 132 patients met the criteria for our study with a total of 50 participants completing the PROMIS and FFI surveys. The average time point at which the outcomes were collected was 5.50 y postoperatively, ranging from 1.65 to 7.57 y. The average PROMIS physical function was 38.35, pain interference was 61.52, and depression was 49.82 for this population. The mean FFI scores were 58.56 for pain, 60.07 for disability, and 48.07 for activity limitation. There was a significant decrease in preoperative and postoperative VAS scores from 5.4 to 2.55 (p < .001). Three patients experienced wound complications related to decreased sensation. Our results indicated that only PROMIS depression scores were within one standard deviation of the population mean following a triple arthrodesis procedure. PROMIS physical function and pain interference were both outside of one standard deviation for the population.

Radiographic Analysis of Valgus Ankle Deformity With or Without Medial Longitudinal Arch Collapse

BACKGROUND

Establishing a surgical plan for ankle deformities necessitates a comprehensive understanding of the deforming forces involved, and the morphology of the ankle deformity plays an important role as well. Valgus tibiotalar tilt development has mostly been described in patients with a low medial longitudinal arch, as seen in progressive collapsing foot deformity (PCFD). However, some valgus ankles demonstrate no radiographic evidence of a collapsed medial arch. This study aims to investigate whether there are differences in the radiographic morphology of valgus ankle deformities between patients with and without a low medial longitudinal arch to explore if they have different etiologies.

METHODS

We retrospectively reviewed patients who underwent surgical treatment for asymmetric valgus ankle deformity at our institution between 2017 and 2021. Patients with a valgus tibiotalar tilt (TT) greater than 4 degrees and Meary angle greater than 30 degrees (mean: 38.9) were included in the PCFD group (n = 29). The non-PCFD group (n = 24) with TT greater than 4 degrees and Meary angle less than 4 degrees (mean: 0.3) was also established. In the weightbearing ankle anteroposterior view, the TT and medial distal tibial angle were measured. Additionally, to assess the mediolateral position of the talus, the talar center migration (TCM) and lateral talar dome-plafond distance (LTD-P) ratio in the coronal plane were measured. In weightbearing computed tomography (WBCT), the degree of axial plane talocalcaneal subluxation and the prevalence of sinus tarsi bony impingement were assessed. Intergroup comparison was conducted.

RESULTS

Both groups demonstrated a similar degree of TT, with a mean of 11.6 degrees in the PCFD group and 13.7 degrees in the non-PCFD group (P = .2330). However, the PCFD group showed a significantly greater TCM and LTD-P ratio compared with those of the non-PCFD group (P < .0001), indicating that PCFD patients have a more medially translated talus in ankle anteroposterior radiographs. WBCT showed that the PCFD group on average had 18 degrees greater axial plane talocalcaneal subluxation (P < .0001) and 52% higher prevalence of sinus tarsi bony impingement (P = .0002) compared with the non-PCFD group.

CONCLUSION

This study suggests that valgus ankles may exhibit different radiographic morphologies depending on the status of the longitudinal arch. Valgus ankles in PCFD patients tend to have a more medially translated talus. This finding may suggest the presence of different deforming forces between the 2 groups and may indicate the need for different treatment strategies to address talar tilt.

LEVEL OF EVIDENCE

Level III, case-control.

Ankle and hindfoot motion of healthy adults during running revealed by dynamic biplane radiography: Side-to-side symmetry, sex-specific differences, and comparison with walking

This study aimed to characterize ankle and hindfoot kinematics of healthy men and women during overground running using biplane radiography, and to compare these data to those previously obtained in the same cohort during overground walking. Participants ran across an elevated platform at a self-selected pace while synchronized biplane radiographs of their ankle and hindfoot were acquired. Motion of the tibia, talus, and calcaneus was tracked using a validated volumetric model-based tracking process. Tibiotalar and subtalar 6DOF kinematics were obtained. Absolute side-to-side differences in ROM and kinematics waveforms were calculated. Side-to-side and sex-specific differences were evaluated at 10 % increments of stance phase with mixed model analysis. Pearson correlation coefficients were used to assess the relationship between stance-phase running and walking kinematics. 20 participants comprised the study cohort (10 men, mean age 30.8 ± 6.3 years, mean BMI 24.1 ± 3.1). Average absolute side-to-side differences in running kinematics waveforms were 5.6°/2.0 mm or less at the tibiotalar joint and 5.2°/3.2 mm or less at the subtalar joint. No differences in running kinematics waveforms between sides or between men and women were detected. Correlations were stronger at the tibiotalar joint (42/66 [64 %] of correlations were p < 0.05), than at the tibiotalar joint (38/66 [58 %] of correlations were p < 0.05). These results provide a normative reference for evaluating native ankle and hindfoot kinematics which may be informative in surgical or rehabilitation contexts. Sex-specific differences in ankle kinematics during overground running are likely not clinically or etiologically significant. Associations seen between walking and running kinematics suggest one could be used to predict the other.

Talonavicular-cuneiform arthrodesis in the management of Mueller-Weiss Syndrome: a retrospective case series

Mueller-Weiss Syndrome (MWS), characterized by spontaneous adult-onset tarsal navicular osteonecrosis, is an uncommon cause of chronic midfoot pain that can lead to functional impairment and progressive deformities. This study aimed to present clinical and radiological outcomes of talonavicular-cuneiform (TNC) arthrodesis in the treatment of patients with MWS. A retrospective study was performed on 8 consecutive patients (6 female, 2 male; mean age = 50 years; range = 33-64) who underwent TNC arthrodesis using plate fixation with autologous bone grafting for the treatment of MWS. To evaluate clinical status, the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Midfoot Score was performed immediately preoperatively and at the final follow-up. In radiographic evaluation, talus-first metatarsal angle (Meary's angle) was measured preoperatively and at the final follow-up. Solid fusion was also examined on postoperative radiographs and computerised tomography. The mean follow-up was 35 months (range = 24-52). The mean AOFAS improved from 37 (range = 24-53) preoperatively to 85 (range = 80-93) at the final follow-up (p < 0.001). No major intra- operative complications were observed in any of the patients. According to the Maceira and Rochera radiological staging system, 5 feet was stage 3, and 3 feet was stage 4. The mean union time was 10 months (range = 5-15). Radiographic solid fusion was achieved in all but one foot that developed talonavicular non-union. TNC arthrodesis using plate fixation with autologous bone grafting seems to be an effective surgical method for reconstruction of MWS.

Does the Presence of Asymptomatic Flatfoot Deformity Impact the Clinical and Radiographic Outcomes of the Minimally Invasive Chevron and Akin Bunionectomy?

BACKGROUND

Flatfoot deformity is believed to play a role in hallux valgus development and recurrence. While symptomatic flatfoot deformity can be treated with separate procedures at the time of hallux valgus correction, the question remains whether the patient undergoing correction of a symptomatic hallux valgus deformity should have their asymptomatic flatfoot concurrently addressed. We aimed to investigate whether the presence of asymptomatic flatfoot influences patient-reported and radiographic outcomes of the minimally invasive chevron and Akin bunionectomy.

METHODS

A total of 104 patients were included in this study. Forty-two asymptomatic patients met the radiographic criteria for flatfoot while 62 had a normal arch. Patient-reported outcomes were evaluated and compared between the two groups using validated PROMIS measures preoperatively and at a minimum one-year postoperatively. Radiographic outcomes including hallux valgus angle (HVA), intermetatarsal angle (IMA), Meary's angle, calcaneal pitch (CP), and talonavicular coverage angle (TNCA) were measured and compared preoperatively and minimum six-months postoperatively.

RESULTS

Both groups demonstrated similar preoperative and postoperative PROMIS scores with significant improvements in physical function, pain interference, pain intensity, and global physical health. Preoperatively, HVA was similar between both groups, however the flatfoot group showed a greater IMA, Meary's angle, TNCA, and lower CP. Postoperatively, HVA and IMA were similar between groups, although patients in the flatfoot group retained a significantly greater Meary's angle, TNCA, and lower CP. Both groups showed significant improvements in HVA, IMA, and TNCA.

CONCLUSION

Our study indicates that the minimally invasive chevron and Akin bunionectomy leads to improved clinical and radiographic hallux valgus outcomes without adversely impacting radiographic flatfoot parameters. Therefore, the MIS bunionectomy may be an effective option for hallux valgus correction in patients with mild, asymptomatic flatfoot.

LEVEL OF EVIDENCE

Level III, retrospective cohort.

Correlation Between Traditional Anteroposterior Radiographic Measurements With Lateral Radiographic Measurements Following Triplanar Correction of Hallux Valgus and With Patient-Reported Outcomes From a Prospective Multicenter Trial

Hallux valgus (HV) is a common condition in which the first ray is deformed, leading to pain and altered joint mechanics. A variety of radiographic measurements are used to evaluate HV. Little is known about measurements used in the assessment of HV on lateral radiographs compared to anteroposterior (AP) radiographs. The primary aim of this study was to correlate lateral measurements with AP measurements pre and postoperatively. The secondary aim was to correlate lateral measurements with patient-reported outcome measures (PROMs) pre and postoperatively. One hundred eighty-three patients were initially enrolled in the study. Two fellowship-trained musculoskeletal radiologists independently performed all measurements. On AP radiographs, hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured. On lateral radiographs, sagittal IMA, Meary's angle, and sagittal first ray length were measured. Measurements were recorded at baseline and 6, 12, and 24 months postoperatively. Intraclass correlation coefficients (ICCs) were used for inter-reader analysis. ICCs were moderate to very strong among readers. There were significant but weak correlations between lateral measurements and AP measurements. For at least 1 timepoint, IMA correlated with sagittal IMA, sagittal first ray length, and Meary's angle. HVA only correlated with sagittal first ray length. These correlations were all weak in magnitude. There were a few significant but weak correlations between the measurements in the study and PROMs. This study showed that sagittal IMA, sagittal first ray length, and Meary's angle are not predictive of AP measurements or patient outcomes and are not useful in preoperative assessment of HV.

The impact of sustentaculum tali fracture on clinical outcome in patients affected by isolated calcaneal fractures

INTRODUCTION

The sustentaculum tali is displaced in almost half of calcaneal fractures and during surgical fixation represents one of the main reference points upon which the other bone has to be reduced. The purpose of this study was to investigate which subtalar joint fracture pattern is more frequently associated with sustentaculum tali involvement. Furthermore, correlation between postoperative clinical outcome and sustentaculum tali integrity was performed.

MATERIAL AND METHODS

Patients with isolated calcaneal fractures were analyzed. Sanders-type fracture and involvement of both sustentaculum tali and calcaneocuboid joint were detected on computed tomography imaging; postoperative AOFAS scores were analyzed according to sustentacular involvement.

RESULTS

Fifty calcaneus fractures in 47 patients were included in the final analysis. The sustentaculum tali was fractured in 18 cases (36.0%), thus contradicting its supposed constant position. Sanders type 3 and 4 fractures were more frequently associated with fractured sustentaculum than type 2 (p = 0.012). Sanders type 4 fractures were associated with displaced sustentacular fragment significantly more than type 2 and 3 (p = 0.043). Patients with intact sustentaculum tali reported significantly higher (p < 0.001) mean AOFAS scores than the uninjured group (84.4 ± 9.1 and 74.3 ± 9.5, respectively).

CONCLUSION

Sanders type 3 and 4 fractures were more frequently associated with sustentaculum tali and/or calcaneocuboid joint involvement than simpler fractures. Injury of sustentaculum tali was related to significant worse postoperative clinical outcomes, underlying the relevance of this fragment on clinical course.

Radiographic Evidence of Sufficient Transverse Plane Alignment after Weil Osteotomy without Screw Fixation

Weil osteotomy is a proven procedure to restore the harmonic distal parabola of the forefoot. In addition to the proximal displacement of the head in the sagittal plane, a displacement in the transverse plane may be necessary, with the refixation of the displaced metatarsal head historically performed by screw fixation. We aimed to determine the radiological differences among 136 feet of 127 patients with 256 Weil osteotomies retrospectively enrolled and divided into groups with (n = 182) and without (n = 74) screw fixation. Demographic data, radiographic union, pre- and postoperative metatarsal angles, and differences in the dorsoplantar view were evaluated. The mean follow-up period was 3.6 months. The mean preoperative metatarsophalangeal angle was 9.24°, and the mean postoperative angle was 12.99°. The restoration of the transversal alignment plane was equally successful in both groups, with a mean extent of angle correction of 10.58°. No nonunions of the osteotomized metatarsals were observed. The radiographic comparisons revealed no significant difference between the groups (p > 0.05). However, visibility of the joint space of the metatarsophalangeal joint was achieved significantly more often in the group without screw fixation (p < 0.05). In the absence of bony malunion and the satisfactory restoration of a harmonious parabola of the forefoot, apparently there does not appear to be a necessity for regular screw fixation after Weil osteotomy based on the available data from the present study.

The Reliability of Common Radiographic Measurements Used to Describe Foot Deformities

Radiographic measurements are frequently used to classify deformity and determine treatment options. Correlation coefficients can be used to determine inter- and intrarater reliability. Reliability is a required feature of any measurement if the measurement is to provide valid information. We calculated correlation coefficients for standard radiographic measurements used to categorize foot deformities: this was done for 52 sets of radiographs assessed by 5 raters. We aimed for generalizability, and kept rater instructions to match what was originally published for each measurement of interest with schematic illustration. Overall, our results mostly showed a lack of inter-rater reliability (correlation coefficients <0.4), and strong intrarater reliability (correlation coefficients >0.6), for 12 forefoot and 12 rearfoot radiographic measurements that are commonly used. The results of this investigation bring into question the routine use of radiographic measurements to categorize deformity, select treatments, and measure surgical outcomes, between surgeons, because the validity of these measurements appears to be threatened by weak inter-rater reliability. In order for these measurements to be considered useful, it may be necessary for surgeons to more rigorously define and practice making standard radiographic measurements.

Imaging modalities for non-acute pathologies of the foot and ankle

Chronic foot and ankle pain, in contrast to acute traumatic injuries, presents a diagnostic challenge due to its diverse underlying causes. Accurate diagnosis often necessitates the utilization of various imaging modalities, emphasizing the importance of selecting the most appropriate one. The intricate structure of the foot, composed of multiple bones and supported by soft tissues like ligaments and plantar fascia, gives rise to a spectrum of mechanical disorders, including stress fractures, plantar fasciitis, Morton's neuroma, and more. In addition to mechanical issues, non-acute abnormalities encompass inflammatory diseases affecting tendons and joints, benign tumors, tumor-like lesions, vascular abnormalities, and others. This article reviews the indispensable role of imaging in the assessment of these conditions, with a focus on plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine studies, tailored to the specific clinical presentation. By providing insights into the selection and interpretation of imaging modalities, this article aims to assist clinicians in achieving accurate diagnoses and optimizing patient care for nonacute foot and ankle pathologies.

Comparison of Foot Kinematics Between Normal Arch and Flexible Flatfoot Using the Oxford Foot Model: A Matched Case-Control Study

Background

Symptomatic flexible flatfoot causes alterations in gait, but exactly how this condition affects the intersegmental motion of the foot during the gait cycle remains unclear. Previous studies have examined the kinematics, yielding inconsistent findings. Therefore, the objective of this study was to investigate how flexible flatfoot deformity, defined as Johnson and Strom classification staging II, affects the intersegmental motion of the foot during fast walking based on a comparison with the matched control group.

Methods

Eleven participants with symptomatic flexible flatfoot and 11 healthy matched control participants were recruited using a foot screening protocol incorporated through a foot physical examinations and radiographic measurements. All demographic characteristics exhibited comparable profiles between the groups. During controlled walking, kinematic outcomes pertaining to the hallux, hindfoot, forefoot, and tibia were collected using the multisegmental Oxford Foot Model.

Results

All spatiotemporal parameters were comparable between the groups. In comparison to the control group, individuals with symptomatic flexible flatfoot demonstrated increased hallux valgus and plantarflexion, increased forefoot abduction, heightened hindfoot eversion, and internal rotation. Notably, no significant major differences were observed in the tibia motion segment. Further, significant correlations were identified between static foot measurements and the extent of the maximum deviation observed during dynamic kinematic assessments.

Conclusion

Compared with age- and gender-matched controls, participants with symptomatic flexible flatfoot exhibited significant gait pattern deviations. A significant correlation also exists between static foot deformity measurements and dynamic kinematic deviations. Collectively, these findings have implications for developing targeted therapeutic interventions to address flexible flatfoot.

Level of evidence

Level III, diagnostic study.

Biomechanical evaluation of the spring ligament and the posterior tibial tendon by shear-waves elastography: validation of a reliable and reproducible measurement protocol

PURPOSE

The anatomy of the spring ligament complex, as well as its pathology, is not well known in daily clinical practice. The purpose of this study was to evaluate the shear-wave elastography properties of the spring ligament and the posterior tibial tendon in healthy adults, and to assess the reliability and reproducibility of these measurements.

METHODS

Shear-wave elastography was used to evaluate both ankles in 20 healthy patients (10 females/10 males) resting on a hinge support with their ankles in neutral, valgus 20° and varus 30° positions. The stiffness of the spring ligament and posterior tibial tendon was assessed by measuring the speed of shear wave propagation through each structure.

RESULTS

Posterior tibial tendon and spring ligament reach a maximum estimated stiffness in valgus 20° position (7.43 m/s vs 5.73 m/s, respectively). Flat feet were associated with greater spring ligament stiffness in the 20° valgus position (p = 0.01), but not for the posterior tibial tendon (p = 0.71). The physiologic weightbearing hindfoot attitude had no impact on the stiffness of the posterior tibial tendon or the spring ligament, regardless of the analysis position. Intra- and inter-observer agreements were all excellent for spring ligament stiffness, regardless of ankle position, and were good or excellent for posterior tibial tendon.

CONCLUSIONS

This study describes a protocol to assess the stiffness of tibialis posterior and the spring ligament by shear-wave elastography, which is reliable, reproducible, and defines a corridor of normality. Further studies should be conducted to define the role of elastography for diagnosis/ evaluation of pathology, follow-up, or surgical strategies.

Imaging of osteoarthritis from the ankle through the midfoot

Ankle, hindfoot, and midfoot osteoarthritis (OA) is most commonly posttraumatic and tends to become symptomatic in younger patients. It often results from instability due to insufficiency of supportive soft tissue structures, such as ligaments and tendons. Diagnostic imaging can be helpful to detect and characterize the distribution of OA, and to assess the integrity of these supportive structures, which helps determine prognosis and guide treatment. However, the imaging findings associated with OA and instability may be subtle and unrecognized until the process is advanced, which may ultimately limit therapeutic options to salvage procedures. It is important to understand the abilities and limitations of various imaging modalities used to assess ankle, hindfoot, and midfoot OA, and to be familiar with the imaging findings of OA and instability patterns.

A foot structure study of new arch flexibility grading system based on three-dimensional arch volume

PURPOSE

Different arch structures may cause different foot function injuries. In the past, the arch structure and flexibility of the foot were often defined by the height of the arch, and there was no three-dimensional (3D) structure classification method. In order to form a more complete 3D description, we propose a new classification system of arch volume flexibility (AVF), and then use this new classification system to investigate the relationship between the AVF and arch index (AI), and the arch height flexibility (AHF) and AI, respectively.

METHODS

It is proposed to recruit 180 young male adults for the test. We obtained arch volume and AI through 3D scanning and obtained the navicular height through manual measurement. Based on these data, we calculated the AHF and the AVF. Using the quintile method, these arches are divided into very stiff, stiff, neutral, flexible, and very flexible. According to AI value, all arches were divided into cavus, rectus, and planus. The distribution of AVF was compared using χ2 goodness of fit test. The spearman correlation test was used to compare the AHF and AVF. A p < 0.05 indicates that the difference is statistically significant.

RESULTS

All participants' plantar data was obtained through 3D scanning, but only 159 of them were complete, so only 318 feet had valid data. The left AHF is (21.23 ± 12.91) mm/kN, and the right AHF is (21.71 ± 12.69) mm/kN. The AVF of the left foot arch is (207.35 ± 118.28) mm3/kg, while the right one is (203.00 ± 117.92) mm3/kg, and the total AVF of the arch was (205.17 ± 117.94) mm3/kg. There was no statistical difference in the AVF between the left and right feet for the same participant (n = 159, p = 0.654). In cavus, the percentage of arch with AVF is 21.4% (very stiff), 21.4% (stiff), 14.3% (neutral), 7.1% (flexible), and 35.7% (very flexible). In rectus, the percentage of arch with AVF is 23.9% (very stiff), 19.6% (stiff), 14.7% (neutral), 24.5% (flexible), and 17.2% (very flexible). In planus, the percentage of arch with AVF is 14.9% (very stiff), 20.6% (stiff), 27.0% (neutral), 16.3% (flexible), and 21.3% (very flexible). Moreover, the correlation between AHF and AVF is not significant (p = 0.060).

CONCLUSION

In cavus, rectus, and planus, different AVF accounts different percentage, but the difference is not statistically significant. AVF is evenly distributed in the arches of the feet at different heights. We further found the relationship between AHF and AVF is not significant. As a 3D index, AVF may be able to describe the flexibility of the arch more comprehensively than AHF.

Ankle and subtalar joint axes of rotation and center of rotation during walking and running in healthy individuals measured using dynamic biplane radiography

The goal of this study was to determine how foot type and activity level affect ankle and hindfoot motion. Dynamic biplane radiography and a validated volumetric registration process was used to measure ankle and hindfoot motion of 20 healthy adults during walking and running. The helical axes of motion (HAM) during stance were calculated at the tibiotalar and subtalar joints. The intersection of each HAM and the rotation plane of interest defined the tibiotalar and subtalar centers of rotation (COR). Correlations between foot type and hindfoot kinematics were calculated using Pearson's correlations. The effect of activity, phase of gait, and dominant vs. non-dominant limb on HAM and COR were evaluated using linear mixed effects models. Activity and phase of gait influenced the superior location of the tibiotalar (p < 0.041) and subtalar (p < 0.044) CORs. Activity and gait phase affected tibiotalar (p < 0.049) and subtalar (p < 0.044) HAM direction during gait. Both HAM orientation and COR location changed with activity and phase of gait. These ankle and hindfoot kinematics have implications for total ankle replacement design and musculoskeletal models that estimate force and moment generating capabilities of muscles.

Flatfeet Severity-Level Detection Based on Alignment Measuring

Flat foot is a postural deformity in which the plantar part of the foot is either completely or partially contacted with the ground. In recent clinical practices, X-ray radiographs have been introduced to detect flat feet because they are more affordable to many clinics than using specialized devices. This research aims to develop an automated model that detects flat foot cases and their severity levels from lateral foot X-ray images by measuring three different foot angles: the Arch Angle, Meary's Angle, and the Calcaneal Inclination Angle. Since these angles are formed by connecting a set of points on the image, Template Matching is used to allocate a set of potential points for each angle, and then a classifier is used to select the points with the highest predicted likelihood to be the correct point. Inspired by literature, this research constructed and compared two models: a Convolutional Neural Network-based model and a Random Forest-based model. These models were trained on 8000 images and tested on 240 unseen cases. As a result, the highest overall accuracy rate was 93.13% achieved by the Random Forest model, with mean values for all foot types (normal foot, mild flat foot, and moderate flat foot) being: 93.38 precision, 92.56 recall, 96.46 specificity, 95.42 accuracy, and 92.90 F-Score. The main conclusions that were deduced from this research are: (1) Using transfer learning (VGG-16) as a feature-extractor-only, in addition to image augmentation, has greatly increased the overall accuracy rate. (2) Relying on three different foot angles shows more accurate estimations than measuring a single foot angle.

A deep learning method for foot-type classification using plantar pressure images

Background: Flat foot deformity is a prevalent and challenging condition often leading to various clinical complications. Accurate identification of abnormal foot types is essential for appropriate interventions. Method: A dataset consisting of 1573 plantar pressure images from 125 individuals was collected. The performance of the You Only Look Once v5 (YOLO-v5) model, improved YOLO-v5 model, and multi-label classification model was evaluated for foot type identification using the collected images. A new dataset was also collected to verify and compare the models. Results: The multi-label classification algorithm based on ResNet-50 outperformed other algorithms. The improved YOLO-v5 model with Squeeze-and-Excitation (SE), the improved YOLO-v5 model with Convolutional Block Attention Module (CBAM), and the multilabel classification model based on ResNet-50 achieved an accuracy of 0.652, 0.717, and 0.826, respectively, which is significantly higher than those obtained using the ordinary plantar-pressure system and the standard YOLO-v5 model. Conclusion: These results indicate that the proposed DL-based multilabel classification model based on ResNet-50 is superior in flat foot type detection and can be used to evaluate the clinical rehabilitation status of patients with abnormal foot types and various foot pathologies when more data on patients with various diseases are available for training.

Unique shape variations of hind and midfoot bones in flatfoot subjects-A statistical shape modeling approach

Flatfoot deformity is a prevalent hind- and midfoot disorder. Given its complexity, single-plane radiological measurements omit case-specific joint interaction and bone shape variations. Three-dimensional medical imaging assessment using statistical shape models provides a complete approach in characterizing bone shape variations unique to flatfoot condition. This study used statistical shape models to define specific bone shape variations of the subtalar, talonavicular, and calcaneocuboid joints that characterize flatfoot deformity, that differentiate them from healthy controls. Bones of the aforementioned joints were segmented from computed tomography scans of 40 feet. The three-dimensional hindfoot alignment angle categorized the population into 18 flatfoot subjects (≥7° valgus) and 22 controls. Statistical shape models for each joint were defined using the entire study cohort. For each joint, an average weighted shape parameter was calculated for each mode of variation, and then compared between flatfoot and controls. Significance was set at p < 0.05, with values between 0.05 ≤ p < 0.1 considered trending towards significance. The flatfoot population showed a more adducted talar head, inferiorly inclined talar neck, and posteriorly orientated medial subtalar articulation compare to controls, coupled with more navicular eversion, shallower navicular cup, and more prominent navicular tuberosity. The calcaneocuboid joint presented trends of a more adducted calcaneus, more abducted cuboid, narrower calcaneal roof, and less prominent cuboid beak compared to controls. Statistical shape model analysis identified unique shape variations which may enhance understanding and computer-aided models of the intricacies of flatfoot, leading to better diagnosis and, ultimately, surgical treatment.

Differential contribution of lateral plantar foot ligaments to lateral column stability - A cadaver based sectioning analysis

Lateral column (LC) instability occurs in adult acquired flatfoot deformity (AAFD). Differential ligament contribution to LC stability is unknown. The primary aim was to quantify this by using cadaver sectioning of lateral plantar ligaments. We also determined the relative contribution of each ligament to dorsal translation of the metatarsal head in the sagittal plane. 17 below-knee cadaveric specimens, preserved by vascular embalming method, were dissected to expose plantar fascia, long/short plantar ligaments (L/SPL), calcaneocuboid (CC) capsule and inferior 4th/5th tarsometatarsal (TMT) capsule. Dorsal forces of 0 N, 20 N and 40 N were applied to the plantar 5th metatarsal head after sequential ligament sectioning in different orders. Pins provided linear axes on each bone, allowing relative angular bone displacements to be calculated. Photography and ImageJ processing software were then used for analysis. The LPL (and CC capsule) had the greatest contribution to metatarsal head motion (107 mm) after isolated sectioning. In the absence of other ligaments, sectioning these resulted in significantly increased hindfoot-forefoot angulation (p ≤ 0.0003). Isolated TMT capsule sectioning demonstrated significant angular displacement even when other ligaments remained intact (with intact L/SPL, p = 0.0005). CC joint instability required both LPL and capsular sectioning for significant angulation to occur, whilst TMT joint stability was largely dependent on its capsule. The relative contribution of static restraints to the lateral arch has not yet been quantified. This study provides useful information on relative ligament contribution to both CC and TMT joint stability, which may in turn improve understanding of surgical interventions used to restore arch stability.

Two-Dimensional and 3-Dimensional MRI Assessment of Progressive Collapsing Foot Deformity-Adult Acquired Flat Foot Deformity

This article is meant to serve as a reference for radiologists, orthopedic surgeons, and other physicians to enhance their understanding of progressive collapsing foot deformity, also known as adult acquired flat foot deformity. Pathophysiology, imaging findings, especially on MRI and 3-dimensional MRI are discussed with relevant illustrations so that the readers can apply these principles in their practice for better patient managements.

Variability of the lower limb symmetry index associated with the gait parameters in the overweight adult population with flatfoot: a case-control study

Background: Adult acquired flatfoot is characterized by a medial arch collapse during monopodal support in the stance phase, developing eversion of the calcaneus and abduction of the forefoot linked to the hindfoot. The purpose of our research was to analyze the dynamic symmetry index in the lower limbs comparing patients with flatfoot and normal foot. Methods: A case-control study was carried out with a sample of 62 participants divided into two groups consisting of 31 participants were overweight with bilateral flatfoot and 31 participants with healthy feet. A portable plantar pressure platform with piezoresistive sensors was used to measure the load symmetry index in the lower limbs in the foot areas and gait phases. Results: Gait pattern analysis showed statistically significant differences in the symmetry index for lateral load (p = 0.004), the initial contact phase (p = 0.025) and the forefoot phase (p < 0.001). Conclusion: The adults were overweight with bilateral flatfoot evidenced alterations in the symmetry index in the lateral load and in the initial contact and flatfoot contact phases, showing greater instability in overweight adult flatfoot compared to the people with normal feet.

Distal Tibia Apex Posterior Angulation: A Normal Anatomic Variant Related to Hindfoot Alignment With Side-to-Side Symmetry

OBJECTIVES

The sagittal plane of the distal tibia has not been well-described. This study sought to characterize sagittal plane morphology, determine symmetry from side to side, and identify differences based on hindfoot alignment.

METHODS

One hundred twelve bilateral lateral weight-bearing ankle radiographs were retrospectively evaluated (224 ankles). Hindfoot alignment was classified as neutral, planus, or cavus using the Meary angle. The angle between the diaphyseal and distal tibia axes was measured, and the apex location relative to the plafond was recorded.

RESULTS

A mean distal tibia apex posterior angulation (DTAPA) of 2.0° (range -2° to 7°, SD = 2.06°) was located 8.0 cm proximal to the plafond. No difference was observed from side to side in DTAPA magnitude (P = 0.36) or location (P = 0.90). Planus alignment was associated with a significantly greater DTAPA (3.05°) as compared with neutral (1.89°) (P = 0.002) and cavus (1.25°) (P < 0.001) alignment.

CONCLUSION

The distal tibia has an apex posterior angulation, suggesting that the true anatomic axis of the tibia terminates just posterior to the plafond center. Hindfoot alignment is related to distal tibia morphology. DTAPA symmetry indicates that contralateral imaging can be used to guide reconstruction of patient-specific anatomy and alignment. Knowledge of the DTAPA may help mitigate sagittal malalignment during distal tibia fracture surgery.

Ankle Instability Update

Sprains are the most frequent injuries of the ankle, especially in sports. Up to 85% of cases affect the lateral ligament complex. Multi-ligament injuries with associated lesions of the external complex, deltoid, syndesmosis, and sinus tarsi ligaments are also common. Most ankle sprains respond to conservative treatment. However, up to 20 to 30% of patients can develop chronic ankle pain and instability.New concepts have been recently developed, based on arthroscopic advances, such as microinstability and rotatory ankle instability. These entities could be precursors of mechanical ankle instability and at the origin of frequently associated ankle injuries, such as peroneus tendon lesions, impingement syndromes, or osteochondral lesions.Imaging methods, especially magnetic resonance (MR) imaging and MR arthrography, are key in precisely diagnosing ligament lesions and associated injuries, facilitating an adequate therapeutic approach.

A Novel Deep Transfer Learning-Based Approach for Automated Pes Planus Diagnosis Using X-ray Image

Pes planus, colloquially known as flatfoot, is a deformity defined as the collapse, flattening or loss of the medial longitudinal arch of the foot. The first standard radiographic examination for diagnosing pes planus involves lateral and dorsoplantar weight-bearing radiographs. Recently, many artificial intelligence-based computer-aided diagnosis (CAD) systems and models have been developed for the detection of various diseases from radiological images. However, to the best of our knowledge, no model and system has been proposed in the literature for automated pes planus diagnosis using X-ray images. This study presents a novel deep learning-based model for automated pes planus diagnosis using X-ray images, a first in the literature. To perform this study, a new pes planus dataset consisting of weight-bearing X-ray images was collected and labeled by specialist radiologists. In the preprocessing stage, the number of X-ray images was augmented and then divided into 4 and 16 patches, respectively in a pyramidal fashion. Thus, a total of 21 images are obtained for each image, including 20 patches and one original image. These 21 images were then fed to the pre-trained MobileNetV2 and 21,000 features were extracted from the Logits layer. Among the extracted deep features, the most important 1312 features were selected using the proposed iterative ReliefF algorithm, and then classified with support vector machine (SVM). The proposed deep learning-based framework achieved 95.14% accuracy using 10-fold cross validation. The results demonstrate that our transfer learning-based model can be used as an auxiliary tool for diagnosing pes planus in clinical practice.

Association of Fusion of the First Metatarsophalangeal Joint and Pes Planus Deformity Correction

BACKGROUND

There has been scant investigation on the relationship between the distal aspect of the medial longitudinal arch and pes planus deformity. The aim of this study was to investigate whether the reduction and stabilization of the distal aspect of the medial longitudinal arch through fusion of the first metatarsophalangeal joint (MTPJ) can subsequently improve pes planus deformity parameters. This could be useful in both further understanding the role of the distal medial longitudinal arch in patients with pes planus and planning operative intervention in patients with multifactorial medial longitudinal arch problems.

METHODS

A retrospective cohort study was undertaken between January 2011 and October 2021, including patients undergoing first MTPJ fusion with a pes planus deformity on weightbearing preoperative radiographs. These were compared to postoperative images, and multiple pes planus measurements were taken for comparison.

RESULTS

A total of 511 operations were identified for further analysis, with 48 feet meeting the inclusion criteria. There was a statistically significant reduction identified between the pre- and postoperative measurements of Meary angle (3.75 degrees, 95% CI 2.9-6.47 degrees) and talonavicular coverage angle (1.48 degrees, 95% CI 1.09-3.44 degrees). There was a statistically significant increase between the pre- and postoperative measurements of calcaneal pitch angle (2.32 degrees, 95% CI 0.24-4.41 degrees) and medial cuneiform height (1.25 mm, 95% CI 0.6-1.92 mm). Reduced intermetatarsal angle was significantly associated with an increase in first MTPJ angle postfusion. Many of the measurements made were found "almost perfectly" reproducible by the Landis and Koch description.

CONCLUSION

Our results demonstrate that fusion of the first MTPJ is associated with improvement of medial longitudinal arch parameters of a pes planus deformity but not to levels considered to be clinically normal. Therefore, the distal aspect of the medial longitudinal arch could, to some degree, be a feature in the pes planus deformity etiology.

LEVEL OF EVIDENCE

Level III, retrospective case control study.

Ligament Insufficiency with Flatfoot: Spring Ligament and Deltoid Ligament

The objective of this article was to review the deltoid ligament and spring ligament specifically as they pertain to ligament insufficiency and adult-acquired flatfoot deformity. Discussion includes the normal and abnormal biomechanical forces that extend through these ligaments in normal and flatfoot deformity. Current literature related to spring ligament repair as part of the flatfoot deformity reconstruction is also reviewed.

Approach to the Ankle in Adult Acquired Flatfoot Deformity

Adult acquired flatfoot is a progressive deformity of the foot and ankle, which frequently becomes increasingly symptomatic. The posterior tibial tendon is most commonly associated with the deformity. A targeted physical examination with plain film radiographs is the recommended initial assessment, which will further guide a physician toward procuring more advanced imaging or toward surgical intervention. In this chapter the authors review the current literature of their approach to the treatment of the ankle in end stage of adult acquired flatfoot deformity.

Sinus tarsi and sinus tarsi syndrome: An imaging review

The sinus tarsi is a funnel-shaped region at the junction of mid-foot and hind-foot which contains fat, vessels, nerves and ligaments. The ligaments help stabilise the subtalar joint and maintain the longitudinal arch of the foot. The nerve endings contain proprioceptive fibres indicating a role for the sinus tarsi in movement of the foot. Sinus tarsi syndrome is a clinical entity characterised by lateral hind-foot pain with worsening on palpation and weight-bearing, and perceived instability. It is associated with both traumatic and non-traumatic causes. Magnetic resonance imaging is the imaging modality of choice for assessment of the sinus tarsi and sinus tarsi syndrome. In this review article, we review the anatomy and various aetiologies of sinus tarsi syndrome, along with the imaging appearances.

Anatomic and Biomechanical Considerations of Flatfoot Deformity

In this article, the authors present essential anatomy in the presence of the postural flat foot. There is a recognition of static versus dynamic stabilizers of the foot. In the continuum of the collapsed foot, there is an exploration of anatomic and pathologic changes. Providing this fundamental knowledge will allow the reader to appreciate the disease process to establish a prognosis and consider treatment alternatives.

Surgically treated adult acquired flatfoot deformity: Register-based study of patient characteristics, health-related quality of life and type of surgery according to severity

BACKGROUND

Population-level data describing patient characteristics and interventions used in surgical treatment of adult acquired flatfoot deformity (AAFD) is lacking.

METHODS

We analyzed baseline patient-reported data including PROMs and surgical interventions for patients with AAFD reported to the Swedish Quality Register for Foot and Ankle Surgery (Swefoot) 2014-2021.

RESULTS

625 feet with primary AAFD surgery were registered. Median age was 60 (range 16-83) years and 64% were women. Mean preoperative EQ-5D index and Self-Reported Foot and Ankle Score (SEFAS) were low. In stage IIa (n = 319) 78% had medial displacement calcaneal osteotomy and 59% had flexor digitorium longus transfer, with some regional variations. Spring ligament reconstruction was less common. In stage IIb (n = 225), 52% had lateral column lengthening, and in stage III (n = 66), 83% had hind-foot arthrodesis.

CONCLUSIONS

Patients with AAFD have low health-related quality of life before surgery. Treatment in Sweden follows best-available evidence but regional variations exist.

LEVEL OF EVIDENCE

III.

Definitions and Measurements of Hindfoot Alignment and Their Biomechanical and Clinical Implications

This article presents a critical review of the past and the current state of the art in defining and measuring hindfoot, ankle, and subtalar alignment. It describes the transition occurring at present from two-dimensional to three-dimensional (3D) alignment measurements, which accompany the emergence of new, functional, high-resolution imaging modalities such as the weight-bearing cone-beam computerized tomography (CT) imaging. To ease and enhance the transition and acceptability of 3D alignment measurements, new acceptable standards for different clinical application are highly desirable.

Tibialis posterior muscle stiffness assessment in flat foot subjects by ultrasound based Shear-Wave Elastography

BACKGROUND

Few methodologies are used to assess Tibialis Posterior muscle stiffness. Those present limitations leading to a lack of evidence. Muscle stiffness assessment can help in the injuries risk factors identification while coupling with Ultrasound based Shear-Wave Elastography for its management. However, a precise and reliable methodology needs to be utilized to increase stiffness accuracy among the entire Tibialis Posterior muscle. Therefore, this study aims to investigate the stiffness association between Tibialis posterior deep and superficial layer and between flat and neutral footed subjects.

METHODS

The sample consisted of 18 participants, where 9 subjects represent the flatfoot group and 9 the neutral foot group. Only the subjects who presented a Navicular Drop Test value of > 9 mm were included in the flatfooted group. All participants were submitted to the Tibialis posterior stiffness assessment with the help of Ultrasound base Shear-Wave Elastography in a lying supine position. Association between Tibialis Posterior deep and superficial layers were determined by Pearson's correlation analysis and group differences were assessed using the U-Mann Whitney test in the comparison between flat foot and neutral foot group (p < 0.05).

RESULTS

No significant correlations between Tibialis Posterior layers stiffness were found (p = 0.194), nor in the comparison between both neutral and flat foot groups (p = 0.424/p = 0.258).

CONCLUSION

Among participants, no associations between tibialis posterior layers stiffness were found. Also, we did not find any differences in the stiffness between flat and neutral foot groups. In this study, the stiffness did not differentiate flat-footed subjects from neutral subjects.

Automated diagnosis of flatfoot using cascaded convolutional neural network for angle measurements in weight-bearing lateral radiographs

OBJECTIVES

Diagnosis of flatfoot using a radiograph is subject to intra- and inter-observer variabilities. Here, we developed a cascade convolutional neural network (CNN)-based deep learning model (DLM) for an automated angle measurement for flatfoot diagnosis using landmark detection.

METHODS

We used 1200 weight-bearing lateral foot radiographs from young adult Korean males for the model development. An experienced orthopedic surgeon identified 22 radiographic landmarks and measured three angles for flatfoot diagnosis that served as the ground truth (GT). Another orthopedic surgeon (OS) and a general physician (GP) independently identified the landmarks of the test dataset and measured the angles using the same method. External validation was performed using 100 and 17 radiographs acquired from a tertiary referral center and a public database, respectively.

RESULTS

The DLM showed smaller absolute average errors from the GT for the three angle measurements for flatfoot diagnosis compared with both human observers. Under the guidance of the DLM, the average errors of observers OS and GP decreased from 2.35° ± 3.01° to 1.55° ± 2.09° and from 1.99° ± 2.76° to 1.56° ± 2.19°, respectively (both p < 0.001). The total measurement time decreased from 195 to 135 min in observer OS and from 205 to 155 min in observer GP. The absolute average errors of the DLM in the external validation sets were similar or superior to those of human observers in the original test dataset.

CONCLUSIONS

Our CNN model had significantly better accuracy and reliability than human observers in diagnosing flatfoot, and notably improved the accuracy and reliability of human observers.

KEY POINTS

• Development of deep learning model (DLM) that allows automated angle measurements for landmark detection based on 1200 weight-bearing lateral radiographs for diagnosing flatfoot. • Our DLM showed smaller absolute average errors for flatfoot diagnosis compared with two human observers. • Under the guidance of the model, the average errors of two human observers decreased and total measurement time also decreased from 195 to 135 min and from 205 to 155 min.