Change in Talar Axial Rotation and Pain Intensity Following Correction of Progressive Collapsing Foot Deformity.

BACKGROUND: The talus is more internally rotated within the ankle mortise in progressive collapsing foot deformity (PCFD) patients. However, no studies have investigated the change in talar axial rotation (AR) in PCFD postoperatively. The primary aim was to investigate the change in talar AR following PCFD reconstruction. Secondary aims were to determine whether talar AR changes were associated with other radiographic measurements or specific procedures, and whether postoperative talar AR was associated with 2-year patient-reported outcome scores. METHODS: Twenty-seven patients older than 18 years who underwent flexible PCFD reconstruction with preoperative and at least 5-month postoperative weightbearing computed tomographic (WBCT) scans and radiographs and had preoperative and at least 2-year postoperative PROMIS scores were included. Patients with talonavicular fusions were excluded. Talar AR was the angle between the transmalleolar axis and talar axis on WBCT scans, with smaller angles representing more internal rotation as described by Kim et al. Hindfoot moment arm, Meary angle, fibulocalcaneal and talocalcaneal distance, subtalar middle facet uncoverage, and talonavicular angle were measured on radiographs. RESULTS: Postoperative talar AR was 49.7 degrees (IQR, 45.9, 57.3), which was more externally rotated than preoperative AR by a median of 8.3 degrees (IQR, 2.2, 15.7) (P > .001). The change in talar AR was not associated with changes in any radiographic parameter. Increasing external talar AR was associated with an increase in postoperative PROMIS pain intensity (rs = 0.38, 95% CI 0.00, 0.67). Lateral column lengthening and subtalar fusion procedures were not associated with changes in talar AR (P > .10). CONCLUSION: PCFD reconstruction results in external rotation of the talus within the ankle mortise. Kim et al found that control patients had approximately 40 to 60 degrees of talar AR, which is similar to this study's corrected position of the talus. However, increasing talar external rotation resulted in worse postoperative PROMIS pain intensity, suggesting the possibility of overcorrecting the internal AR deformity.

Clinical and radiological outcomes of flexible flatfoot correction with double calcaneal osteotomy.

BACKGROUND: Although double calcaneal osteotomy (medial displacement calcaneal osteotomy with lateral column lengthening) is widely regarded as an effective treatment option for flexible flatfoot, limited studies have extensively analyzed the degree of deformity correction in three dimensions following double calcaneal osteotomy. This study was performed to evaluate the radiographic and clinical effectiveness of double calcaneal osteotomy to correct flexible flatfoot deformities. METHODS: Thirty-one patients who had 44 symptomatic flexible flatfeet and underwent double calcaneal osteotomy were examined retrospectively with a mean follow-up of 50 months. Visual analog scale, foot and ankle activity measure, and other clinical data were obtained from medical records. Various radiographic variables for assessing flatfoot and osteoarthritic change in tarsal joints were analyzed from weightbearing radiographs. RESULTS: Clinical scores and radiographic variables were significantly improved postoperatively. The mean values of medial sliding and lateral lengthening were 7.6 and 8.7 mm, respectively. No osteoarthritic changes were observed. CONCLUSIONS: Double calcaneal osteotomy could be used to correct flatfoot deformities effectively and sustainably and provide symptomatic relief and patient satisfaction. LEVEL OF EVIDENCE: Level 4, retrospective case series.

Weight-Bearing Computed Tomography of the Foot and Ankle-What to Measure?

Weight-bearing computed tomography (WBCT) was introduced in 2012 for foot and ankle applications as a breakthrough technology that enables full weight-bearing, three-dimensional imaging unaffected by x-ray beam projections or foot orientation. The literature describing the use of WBCT in the treatment of foot and ankle disorders is growing, and this article provides an overview of what can be measured with WBCT.

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.

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.

An ex vivo sequential ligament transection model of flatfoot.

BACKGROUND: The ligaments implicated in the earliest stages of developing a progressive collapsing foot deformity are poorly understood. Commonly employed cadaveric flatfoot models are created from simultaneous transection of multiple ligaments, making it difficult to assess early changes in pressure distribution from ligaments critical for maintaining load distribution. A serial transection of ligaments may provide insight into changes in pressure distribution under the foot to identify a potential combination of ligaments that may be involved in early deformities. METHODS: Specimens were loaded using a custom designed axial and tendon loading system. Plantar pressure data for the forefoot and hindfoot were recorded before and after six sequential ligament complex transections. FINDINGS: Sectioning the plantar fascia (first) and short/long plantar ligaments (second) failed to generate appreciable differences in load distribution. Dividing the spring ligament (third) led to changes in hindfoot load distribution with a shift towards the lateral column indicative of hindfoot valgus angulation. All subsequent conditions resulted in similar patterns in hindfoot plantar load distribution. An anterior shift in the center of pressure only occurred after transection of all six ligament complexes. INTERPRETATION: Loss of the plantar fascia and short/long plantar ligaments are not critical in maintaining plantar load distribution or contact area. However, the additional loss of the spring ligament caused notable changes in hindfoot load distribution, indicating the combination of these three ligament complexes is particularly critical for preventing peritalar subluxation. Minimal changes in load distribution occurred when performing additional transections to reach a complete flatfoot deformity.

Impact of Subtalar Distraction Arthrodesis on Ankle Joint: Radiological Insights from Modified Grice-Green Procedure.

Subtalar distraction arthrodesis (SDA) is a surgical procedure designed to treat hindfoot deformities associated with isolated subtalar joint arthritis. In 1996, Fitzgibbons was the first to observe that, in some cases, hindfoot fusion appeared to be associated with the development of tibiotalar valgus tilt. Since then, few studies have addressed this issue. Given that hindfoot fusion can be performed using various techniques, this study investigated the potential tibiotalar joint frontal or sagittal modifications resulting from the modified Grice-Green technique. All the consecutive patients who underwent the modified Grice-Green procedure were included. The patient records were reviewed to extract demographic data. Weight-bearing foot and ankle radiographs were assessed to measure the talar tilt angle and the tibiotalar ratio on the same picture archiving and communication system by three independent observers. A total of 69 patients met the criteria for inclusion. The mean talar tilt showed no substantial changes, since the increase from 1.46 ± 1.62 preoperatively to 1.93 ± 2.19 at a minimum of 8 months postoperatively was not statistically significant (p = 0.47). The average preoperative tibiotalar ratio significantly increased from 33.4 ± 4.4% to 35 ± 4% postoperatively (p = 0.007), although remaining within the normal range, indicating a possible realignment of the posterior facet of the subtalar joint. In conclusion, this study highlights the effectiveness of the modified Grice-Green procedure in achieving a favorable realignment without impacting the ankle joint, particularly regarding tibiotalar valgus tilt.

Clinical outcomes of subtalar arthroereisis for the treatment of stage 1 flexible progressive collapsing foot deformity.

BACKGROUND: The use of subtalar arthroereisis as an adjunct to the surgical treatment of stage 1 flexible progressive collapsing foot deformity (PCFD) is controversial. The aim was to investigate the clinical outcomes and report the implant removal rate of subtalar arthroereisis as an adjunct for stage 1 PCFD. METHODS: A retrospective study of 212 consecutive feet undergoing operative management of stage 1 PCFD with adjunctive subtalar arthroereisis between October 2010 and April 2018. The primary outcome was the Foot and Ankle Outcome Score (FAOS). Secondary outcomes included Foot and Ankle Disability Index (FADI), Euroqol-5D-5L Index and implant removal rate. RESULTS: Post-operative clinical FAOS outcomes were collected for 153 feet (72.2%). At mean 2.5-year follow-up, the mean ± standard deviation FAOS for each domain was as follows; Pain: 81.5 ± 18.5, Symptoms: 79.5 ± 12.9, Activities of Daily Living: 82.5 ± 15.4 and Quality of Life: 64.2 ± 23.7. EQ-5D-5L Index was 0.884 ± 0.152. Pre-operative scores were available for 20 of these feet demonstrating a statistically significant improvement in all FAOS, FADI and EQ-5D-5L domains (p < 0.05). The implant removal rate for persistent sinus tarsi pain was 48.1% (n = 102). CONCLUSION: Use of a subtalar arthroereisis implant as an adjunct to conventional procedures in stage 1 flexible PCFD can result in significant improvement in pain and function. Patients should be counselled as to the relatively frequent rate of subsequent implant removal. LEVEL OF EVIDENCE: IV.

Defining the patient acceptable symptom state using PROMIS following reconstruction of the progressive collapsing foot deformity.

BACKGROUND: The patient acceptable symptom state (PASS) represents the threshold beyond which patients are satisfied with their outcome. This study aimed to define PASS thresholds for progressive collapsing foot deformity (PCFD) reconstruction using Patient-Reported Outcomes Measurement Information System (PROMIS) scores and anchor question responses. METHODS: This retrospective study consisted of 109 patients who underwent flexible PCFD reconstruction, had preoperative and 2-year postoperative PROMIS scores, and 2-year postoperative anchor question responses. ROC curve analyses were performed to quantify PASS thresholds. RESULTS: PASS thresholds for the PROMIS Physical Function (PF) and Pain Interference (PI) domains were found to be lower and higher, respectively, than population norms. Furthermore, patients with higher preoperative PROMIS PF scores or lower preoperative PROMIS PI scores had a significantly higher likelihood of achieving the PASS thresholds. CONCLUSION: In addition to guiding future outcomes research, these results may help surgeons optimize treatment for PCFD and better manage patient expectations. LEVEL OF EVIDENCE: III, retrospective cohort study.

Impact of the medial displacement calcaneal osteotomy on foot biomechanics: a systematic literature review.

INTRODUCTION: Progressive collapsing foot deformity (PCFD), formally known as "adult-acquired flatfoot deformity" (AAFFD), is a complex foot deformity consisting of multiple components. If surgery is required, joint-preserving procedures, such as a medial displacement calcaneal osteotomy (MDCO), are frequently performed. The aim of this systematic review is to provide a summary of the evidence on the impact of MDCO on foot biomechanics. MATERIALS AND METHODS: A systematic literature search across two major sources (PubMed and Scopus) without time limitation was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) criteria. Only original research studies reporting on biomechanical changes following a MDCO were included. Exclusion criteria consisted of review articles, case studies, and studies not written in English. 27 studies were included and the methodologic quality graded according to the QUACS scale and the modified Coleman score. RESULTS: The 27 included studies consisted of 18 cadaveric, 7 studies based on biomechanical models, and 2 clinical studies. The impact of MDCO on the following five major parameters were assessed: plantar fascia (n = 6), medial longitudinal arch (n = 9), hind- and midfoot joint pressures (n = 10), Achilles tendon (n = 5), and gait pattern parameters (n = 3). The quality of the studies was moderate to good with a pooled mean QUACS score of 65% (range 46-92%) for in-vitro and a pooled mean Coleman score of 58 (range 56-65) points for clinical studies. CONCLUSION: A thorough knowledge of how MDCO impacts foot function is key in properly understanding the postoperative effects of this commonly performed procedure. According to the evidence, MDCO impacts the function of the plantar fascia and Achilles tendon, the integrity of the medial longitudinal arch, hind- and midfoot joint pressures, and consequently specific gait pattern parameters.

Isolated Talonavicular Arthrodesis as Treatment for Flexible Progressive Collapsing Foot Deformity: A Case Series.

Background: For the younger, more active patient with flexible symptomatic progressive collapsing foot deformity (PCFD), joint-sparing procedures may be preferred to preserve functional motion. Isolated talonavicular (TN) arthrodesis has been described for treatment of rigid and flexible PCFD for patients that are older and less active whose deformity is still correctable through the TN joint. The purpose of this study was to evaluate radiographic and clinical outcomes in patients with PCFD treated with isolated triplanar correction with a TN joint arthrodesis. Methods: Forty-nine patients (53 feet) with flexible PCFD underwent isolated TN arthrodesis. Weightbearing radiographs were performed pre- and postoperatively, and measurements included lateral talar-first metatarsal angle, calcaneal pitch, TN coverage angle, and the anteroposterior (AP) talar-first metatarsal angle. The Foot and Ankle Ability Measure (FAAM) and Veterans-Rand 12-Item Health Survey (VR-12) scores were also collected. Results: Thirty-five females and 14 males were evaluated with a mean age of 63 years, at an average follow-up of 41.3 months. Significant improvements were found radiographically. Lateral radiographs demonstrated improvements in lateral talar-first metatarsal angle from 25.2 degrees preoperatively to 9.5 degrees postoperatively (P < .001) and calcaneal pitch from 14.9 degrees preoperatively to 17.5 degrees postoperatively (P < .001). AP radiographs showed the TN coverage angle improving from 35.0 degrees to 4.9 degrees postoperatively (P < .001) and AP talar-first metatarsal angle improving from 17.3 degrees to 5.9 degrees postoperatively (P < .001). Clinical outcomes were improved in the FAAM pain score (48.6 to 39.2, P = .130), FAAM ADL score (53.8 to 69.2, P = .002), FAAM Sport score (29.5 to 40.7, P = .099), and the overall FAAM score (47.7 to 63.1, P = .006). Patient satisfaction with medical care was 85.2/100 postoperatively. Conclusion: Isolated TN arthrodesis is a viable surgical option for older, lower-demand patients with flexible PCFD. This study demonstrated significant improvements in radiographic alignment and FAAM scores. Comparative studies with other surgical procedures should be performed to determine which is the best technique for older, lower-demand patients with flexible PCFD. Level of Evidence: Level III, retrospective cohort study.

Peroneus Brevis to Longus Tendon Transfer in the Treatment of Flexible Progressive Collapsing Foot Deformity: A Cadaveric Study.

BACKGROUND: Although operative treatment of the flexible progressive collapsing foot deformity (PCFD) remains controversial, correction of residual forefoot varus and stabilization of the medial column are important components of reconstruction. A peroneus brevis (PB) to peroneus longus (PL) tendon transfer has been proposed to address these deformities. The aim of our study was to determine the effect of an isolated PB-to-PL transfer on medial column kinematics and plantar pressures in a simulated PCFD (sPCFD) cadaveric model. METHODS: The stance phase of level walking was simulated in 10 midtibia cadaveric specimens using a validated 6-degree of freedom robot. Bone motions and plantar pressure were collected in 3 conditions: intact, sPCFD, and after PB-to-PL transfer. The PB-to-PL transfer was performed by transecting the PB and advancing the proximal stump 1 cm into the PL. Outcome measures included the change in joint rotation of the talonavicular, first naviculocuneiform, and first tarsometatarsal joints between conditions. Plantar pressure outcome measures included the maximum force, peak pressure under the first metatarsal, and the lateral-to-medial forefoot average pressure ratio. RESULTS: Compared to the sPCFD condition, the PB-to-PL transfer resulted in significant increases in talonavicular plantarflexion and adduction of 68% and 72%, respectively, during simulated late stance phase. Talonavicular eversion also decreased in simulated late stance by 53%. Relative to the sPCFD condition, the PB-to-PL transfer also resulted in a 17% increase (P = .045) in maximum force and a 45-kPa increase (P = .038) in peak pressure under the first metatarsal, along with a medial shift in forefoot pressure. CONCLUSION: The results from this cadaver-based simulation suggest that the addition of a PB-to-PL transfer as part of the surgical management of the flexible PCFD may aid in correction of deformity and increase the plantarflexion force under the first metatarsal. CLINICAL RELEVANCE: This study provides biomechanical evidence to support the addition of a PB-to-PL tendon transfer in the surgical treatment of flexible PCFD.

Does foot shape really matter? Correlation of patient reported outcomes with radiographic assessment in progressive collapsing foot deformity reconstruction: A systematic review.

BACKGROUND: In progressive collapsing foot deformity (PCFD), the goal of surgery is to obtain a well-balanced plantigrade foot. It remains unclear if restoration of the alignment and subsequent improvement in radiological parameters is associated with improved patient-reported outcome measures (PROMs). The aim of the current systematic review was to investigate whether there is a correlation between radiographic assessment and PROMs in patients treated surgically for flexible PCFD. MATERIALS AND METHODS: The study was conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. A comprehensive literature search was performed in Pubmed, EMBASE, Cochrane Central Register of Controlled Trails (CENTRAL), and KINAHL. We included all the studies reporting both PROMs and radiological outcomes in patients treated surgically for PCFD. The quality of the included studies was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal tool. RESULTS: Six retrospective studies were included. Radiological parameters related to forefoot plantarflexion were associated with statistically significant differences in postoperative PROMs. A neutral hindfoot and midfoot position was positively correlated with postoperative PROMs but a statistically significant difference could not be established in all studies. The medial arch height was positively correlated with PROMs, but in one study this was the case only in revision surgeries. CONCLUSION: The literature so far suggests restoration of the alignment may be associated with improved PROMs. Future prospective studies that investigate possible radiological and clinical correlations in PCFD surgery are needed. LEVEL OF EVIDENCE: III.

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.

Association Between Weightbearing CT and MRI Findings in Progressive Collapsing Foot Deformity.

BACKGROUND: Weightbearing computed tomography (WBCT) scans allow for a better understanding of foot alignment in patients suffering from progressive collapsing foot deformity (PCFD). However, soft tissue integrity (eg, spring ligament complex or tibialis posterior tendon) cannot be easily assessed via WBCT. As performing both WBCT and magnetic resonance imaging (MRI) might not be cost effective, we aimed to assess whether there is an association between osseous and soft tissue findings in WBCT and MRI. METHODS: In this observational study, a consecutive cohort of 24 patients of various stages of PCFD (mean age 51 ± 18 years) underwent WBCT scans and MRI. Twenty-four healthy individuals of similar age, body mass index (BMI), and sex with WBCT scans were used as a control group. In addition to of osseous sinus tarsi impingement, 4 commonly used 3-dimensional (3D) measurements (talocalcaneal overlap [TCO], talonavicular coverage [TNC], Meary angle [MA], axial/lateral) were obtained using a dedicated postprocessing software (DISIOR 2.1, Finland) on the WBCT data sets. Sinus tarsi obliteration, spring ligament complex, tibiospring ligament integrity, as well as tibialis posterior tendon degeneration were evaluated with MRI. Statistical analysis was performed for significant (P < .05) correlation between findings. RESULTS: None of the assessed 3D measurements correlated with either spring ligament complex or tibiospring ligament tears. BMI and TCO were found to be associated with tibialis posterior tendon tears. Seventy-five percent of patients with osseous sinus tarsi impingement on WBCT also showed signs of sinus tarsi obliteration on MRI. CONCLUSION: Although WBCT reflects foot alignment and can reveal osseous sinus tarsi impingement in PCFD patients, the association between WBCT-based 3D measurements and ligament or tendon tears assessed via MRI is limited. WBCT appears complimentary to MRI regarding its diagnostic value. Both imaging options add important information and may impact decision making in the treatment of PCFD patients. LEVEL OF EVIDENCE: Level IV, observational study.

Biomechanical Effects of Subtalar Joint Fusion and Medial Ligament Reconstruction in Simulated Progressive Collapsing Foot Deformity.

BACKGROUND: The purpose of this study is to investigate the biomechanical effect of medial displacement calcaneal osteotomy (MDCO), subtalar joint fusion (SF), and medial ligament reconstruction (MLR: deltoid-spring ligament) in a severe flatfoot model. We hypothesized that (1) combination of MDCO and SF improves the tibiotalar and foot alignment in severe progressive collapsing foot deformity (PCFD) cadaver model. (2) However, if a residual valgus heel alignment remains after MCDO and SF, it can lead to increased medial ligament strain, foot malalignment, and tibiotalar valgus tilt, which will be mitigated by the addition of MLR. METHODS: Ten fresh-frozen cadaveric foot specimens were used to create a severe flatfoot model. The foot alignment changes, including the talo-first metatarsal angle in the axial and sagittal planes, subtalar angle, and tibiotalar angle in the coronal plane, were measured. The angles were measured at the initial condition, after creating the severe flatfoot model, and after each successive reconstructive procedure in the following order: (1) MDCO, (2) SF, and (3) MLR. RESULTS: Tibiotalar valgus tilt was decreased with the MDCO procedure: 4.4 vs 1.0 degrees (P = .04). Adding in situ SF to the MDCO led to increased tibiotalar tilt to 2.5 degrees was different from the initial condition (P = .01). Although the tibiotalar valgus tilt was significantly decreased after adding the MLR to the MDCO/SF procedure compared with the severe flatfoot model (0.8 vs 4.4 degrees, P = .03), no significant difference in the tibiotalar valgus tilt was observed between MDCO/SF and MDCO/SF with MLR. CONCLUSION: Our results demonstrated that MDCO significantly improved forefoot abduction and medial arch alignment, with no significant additional improvement observed with addition of SF. Following SF, a residual valgus heel alignment can contribute to subsequent tibiotalar valgus tilt. The addition of MLR did not show significantly decreased tibiotalar valgus tilt following SF. CLINICAL RELEVANCE: Residual valgus heel alignment after subtalar joint fusion in the surgical treatment of PCFD can lead to increased medial ligament strain. Although MLR might be considered for providing medial stability, it may not necessarily prevent the development of tibiotalar valgus tilt.

What's the clinical significance of VAS, AOFAS, and SF-36 in progressive collapsing foot deformity.

BACKGROUND: This study aimed to ascertain the minimal clinically important difference (MCID), and substantial clinical benefit (SCB) of the American Orthopedic Foot and Ankle Society (AOFAS) scale, visual analog scale (VAS) for pain, and Short Form-36 Health Survey (SF-36) in progressive collapsing foot deformity (PCFD) surgery. METHODS: In this retrospective cohort study, a total of 84 patients with PCFD (84 feet) who underwent surgery between July 2015 and April 2021 were included. The study assessed the patients' subjective perception, as well as their VAS, AOFAS, and SF-36 scores at a minimum two-year follow-up, and these data were subjected to statistical analysis. The study utilized Spearman correlation analysis to determine the degree of correlation between patients' subjective perception and their VAS, AOFAS, and SF-36 scores. The minimal detectable change (MDC), MCID, and SCB for VAS, AOFAS, and SF-36 were calculated using both distribution- and anchor-based methods. The classification outcomes obtained from the distribution- and anchor-based methods were assessed using Cohen's kappa. RESULTS: Based on the subjective perception of the patients, a total of 84 individuals were categorized into three groups, with 7 in the no improvement group, 14 in the minimum improvement group, and 63 in the substantial improvement group. Spearman's correlation analysis indicated that the patients' subjective perception exhibited a moderate to strong association with VAS, AOFAS, SF-36 PCS, and SF-36 MCS, with all coefficients exceeding 0.4. The MCID of VAS, AOFAS, SF-36 PCS, and SF-36 MCS in PCFD surgery were determined to be 0.93, 5.84, 4.15, and 4.10 points using the distribution-based method and 1.50, 10.50, 8.34, and 3.03 points using the anchor-based method. The SCB of VAS, AOFAS, SF-36 PCS, and SF-36 MCS in PCFD surgery were 2.50, 18.50, 11.88, and 6.34 points, respectively. Moreover, the preliminary internal validation efforts have demonstrated the practical application and clinical utility of these findings. With the exception of the distribution-based MCID of SF-36 PCS, which showed fair agreement, all other measures demonstrated moderate to almost perfect agreement. CONCLUSIONS: The MDC, MCID, and SCB intuitively enhance the interpretation of VAS, AOFAS, and SF-36 in PCFD surgery, assisting all stakeholders to better understand the therapeutic benefits and limitations of clinical care, and thus to make a more rational decision. Each of these parameters has its own emphasis and complements the others. These parameters are recommended for evaluating the clinical relevance of the results, and their promotion should extend to other areas of foot and ankle surgery.

The Role of the Transverse Arch in Progressive Collapsing Foot Deformity.

BACKGROUND: The transverse arch (TA) has recently been shown to significantly increase the intrinsic stiffness of the midfoot when coupled with the medial longitudinal arch (MLA). Progressive collapsing foot deformity (PCFD) is a complex deformity that ultimately results in a loss of stiffness and collapse of the MLA. The role of the TA has not been investigated in patients diagnosed with this disorder using weightbearing CT (WBCT). Therefore, this study aims to answer the following questions: (1) Is the curvature of the TA decreased in PCFD? (2) Where within the midfoot does TA curvature flattening happen in PCFD? METHODS: A retrospective review of weightbearing CT images was conducted for 32 PCFD and 32 control feet. The TA curvature was assessed both indirectly using previously described methods and directly using a novel measurement termed the transverse arch plantar (TAP) angle that assesses the angle formed between the first, second, and fifth metatarsals in the coronal plane. Location of TA collapse was also assessed in the coronal plane. RESULTS: The TAP angle was significantly higher in PCFD (mean 115.2 degrees, SD 10.7) than in the control group (mean 100.8 degrees, SD 7.9) (P < .001). No difference was found using the calculated normalized TA curvature between PCFD (mean 17.1, SD 4.8) and controls (mean 18.3, SD 4.0) (P = .266). Location of collapse along the TA in PCFD was most significant at the second metatarsal and medial cuneiform. CONCLUSION: The TA is more collapsed in PCFD compared to controls. This collapse was most substantial between the plantar medial cuneiform and the plantar second metatarsal. This may represent a location of uncoupling of the TA and MLA. LEVEL OF EVIDENCE: Level III, retrospective case control.

Medializing Calcaneal Osteotomy for progressive collapsing foot deformity alters the three-dimensional subtalar joint alignment.

BACKGROUND: A medializing calcaneal osteotomy (MCO) is considered as one of the key inframalleolar osteotomies to correct progressive collapsing foot deformity (PCFD). While many studies were able to determine the post-operative hind- and midfoot alignment, alternations of the subtalar joint alignment remained obscured by superposition on plain radiography. Therefore, we aimed to assess the hind-, midfoot- and subtalar joint alignment pre- compared to post-operatively using 3D weightbearing CT (WBCT) imaging. METHODS: Seventeen patients with a mean age of 42 ± 17 years were retrospectively analyzed. Inclusion criteria consisted of PCFD deformity corrected by a medializing calcaneal osteotomy (MCO) as main procedure and imaged by WBCT before and after surgery. Exclusion criteria were patients who had concomitant calcaneal lengthening osteotomies, mid-/hindfoot fusions, hindfoot coalitions, and supramalleolar procedures. Image data were used to generate 3D models and compute the hindfoot (HA), midfoot (MA) - and subtalar joint (STJ) alignment in the coronal, sagittal and axial plane, as well as distance maps. RESULTS: Pre-operative measurements of the HA and MA improved significantly relative to their post-operative equivalents p < 0.05). The post-operative STJ alignment showed significant inversion (2.8° ± 1.7), abduction (1.5° ± 1.8), and dorsiflexion (2.3° ± 1.7) of the talus relative to the calcaneus (p < 0.05) compared to the pre-operative alignment. The displacement between the talus and calcaneus relative to the sinus tarsi increased significantly (0.6 mm±0.5; p < 0.05). CONCLUSION: This study detected significant changes in the sagittal, coronal, and axial plane alignment of the subtalar joint, which corresponded to a decompression of the sinus tarsi. These findings contribute to our clinical practice by demonstrating the magnitude of alteration in the subtalar joint alignment that can be expected after PCFD correction with MCO as main procedure.