Adult Acquired Flatfoot Deformity Research Articles

Biomechanical effects of Evans versus Hintermann osteotomy for treating adult acquired flatfoot deformity: a patient-specific finite element investigation.

Evans and Hintermann lateral column lengthening (LCL) procedures are both widely used to correct adult acquired flatfoot deformity (AAFD), and have both shown good clinical results. The aim of this study was to compare these two procedures in terms of corrective ability and biomechanics influence on the Chopart and subtalar joints through finite element (FE) analysis. Twelve patient-specific FE models were established and validated. The Hintermann osteotomy was performed between the medial and posterior facets of the subtalar joint; while, the Evans osteotomy was performed on the anterior neck of the calcaneus around 10mm from the calcaneocuboid joint surface. In each procedure, a triangular wedge of varying size was inserted at the lateral edge. The two procedures were then compared based on the measured strains of superomedial calcaneonavicular ligaments and planter facia, the talus-first metatarsal angle, and the contact characteristics of talonavicular, calcaneocuboid and subtalar joints. The Hintermann procedure achieved a greater correction of the talus-first metatarsal angle than Evans when using grafts of the same size, indicating that Hintermann had stronger corrective ability. However, its distributions of von-Mises stress in the subtalar, talonavicular and calcaneocuboid joints were lesshomogeneous than those of Evans. In addition, the strains of superomedial calcaneonavicular ligaments and planter facia of Hintermann were also greater than those of Evans, but both generally within the safe range (less than 6%). This FE analysis study indicates that both Evans and Hintermann procedures have good corrective ability for AAFD. Compared to Evans, Hintermann procedure can provide a stronger corrective effect while causing greater disturbance to the biomechanics of Chopart joints, which may be an important mechanismof arthritis. Nevertheless, it yields a better protection to the subtalar joint than Evans osteotomy. Both Evans and Hintermann LCL surgeries have a considerable impact on adjacent joints and ligament tissues. Such effects alongside the overcorrection problem should be cautiously considered when choosing the specific surgical method. Level III, case-control study.

Cotton Osteotomy: An Integral Midfoot Procedure for Forefoot Varus Correction

Forefoot varus is a component of the adult-acquired flatfoot deformity which had to be dealt with independently because isolated hindfoot procedures are insufficient to address this deformity. The dorsal opening wedge osteotomy of the medial cuneiform also known as the Cotton osteotomy is an effective and reliable procedure in the correction of forefoot varus with consistently reported good outcomes in terms of improved radiographic and functional outcomes with excellent bony union rate. Notably, it is also very versatile in that the degree of sagittal correction can be adjusted freely. The use of anatomic Cotton plates with titanium wedge integration makes the osteotomy even more robust with the prevention of early loss of correction and reduction of shear forces at the osteotomy site. Therefore, we describe our technique and experience using an anatomic Cotton plate with titanium wedge integration in Cotton osteotomy for forefoot varus. Level of Evidence: Level V.

Comparison of the Acute Postoperative Complications Between Isolated Talonavicular Versus Talonavicular and Subtalar (Double) Arthrodesis in Flatfoot Deformity.

Both isolated talonavicular arthrodesis and talonavicular and subtalar (such as double) arthrodesis can be effective treatments for adult-acquired flatfoot deformity (AAFD) with good success rates, but double arthrodesis has become more commonly performed in recent years. The purpose of this study is to evaluate whether isolated talonavicular versus talonavicular and subtalar arthrodesis led to significantly different 30-day postoperative complication rates in patients with AAFD. We performed a retrospective review to identify a large cohort of adult patients with the diagnosis of AAFD or posterior tibial tendon deformity (PTTD) who underwent isolated talonavicular or talonavicular and subtalar arthrodesis between 2006 and 2020 from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). To investigate whether there was a difference in complication rate between the 2 surgical cohorts, we estimated logistic regression models and log-binomial models on each of the outcomes while also adjusting for sex and age. We found that there was no significant difference in the rate of major complications (P = .567) or readmissions (P = .567) between patients who underwent isolated talonavicular versus talonavicular and subtalar arthrodesis for AAFD. However, there was a significantly higher rate of minor complications in patients who underwent isolated talonavicular arthrodesis when compared with patients who underwent talonavicular and subtalar arthrodesis (P = .009). This study found that there was no increased risk of 30-day postoperative complications or readmissions with talonavicular and subtalar arthrodesis when compared with isolated talonavicular arthrodesis for AAFD. In addition, there was no increased risk of major complications for talonavicular and subtalar arthrodesis when compared with isolated talonavicular arthrodesis, and isolated talonavicular arthrodesis actually carried a higher risk of minor complications for this surgical cohort. This may provide valuable information for surgeons considering surgical treatment for a particular case of AAFD. Level III.

An Update Management of Pes Planus and Pes Cavus

This review article provided an update on managing pes planus and pes cavus, two common foot deformities caused by an imbalance of the forces acting on the foot. The article described the stages of adult-acquired flatfoot deformity and its causes, risk factors, and treatment options, including conservative and surgical approaches. The report also provided information on the clinical and radiological assessment of the condition and the use of various modalities such as orthotics and braces, physical therapy, and medication

Analysis of Patient-Reported Outcomes Following Triple Arthrodesis: A Minimum Two-Year Followup

Category: Hindfoot Introduction/Purpose: Adult acquired flatfoot deformity (AAFD) is a debilitating condition that is common in the United States. Triple arthrodesis (TA) is a treatment option reserved for advanced disease. Evidence on patient outcomes following this procedure remains limited. This study aims to report patient-reported outcomes following TA via patient reported outcome measurement information systems (PROMIS). Secondary aims are to delineate any demographics or patient characteristics that significantly impact PROMIS scoring. Methods: In this single institution study, we identified all patients who underwent triple arthrodesis between 2014 and 2021 based on CPT coding. Patients who underwent a TA procedure for AAFD with a minimum of 24 months follow-up were eligible for inclusion in this study. Patients under the age of 18, those undergoing revision surgeries, or those with pathologies other than AAFD were excluded from this study. Patient demographics and surgical complications were collected through chart review. The Patient Reported Outcomes Measurement Information System (PROMIS) survey and Foot Function Index (FFI) scores were collected via telephone interview. PROMIS scores were analyzed with a Type III “SS” ANOVA test to stratify independent risk factors and account for confounding variables. Results: 49 patients (43%) submitted responses to the survey. Patient outcomes were collected at an average of 5.50 years postoperatively. There were no significant differences in the rates of complications among any of the variables analyzed. The average PROMIS physical function score was 38.35, the average pain interference score was 61.52, and the average depression score was 49.82. Males and patients with prior foot and ankle procedures had significant increases in PROMIS physical function scores (p <.05). The mean FFI scores were 58.56 for pain, 60.07 for disability, and 48.07 for activity limitation. Patients > 50 years old had significantly higher FFI pain, disability, and total scores (p <.05). VAS scores decreased preoperatively to postoperatively from 5.4 to 2.6. Conclusion: Our study is the first to examine variables significantly impacting PROMIS, FFI and VAS scores for patients undergoing TA for AAFD. Treatment of AAFD with TA appears to be beneficial in long-term reduction of pain. This study is one of the largest to date involving patient reported outcomes following TA and can serve as a prognostic tool for physicians to use when counseling patients prior to this procedure.

A Modified Technique for Lateral Column Lengthening as Part of Adult Acquired Flatfoot Deformity Correction: An Intact Medial Calcaneal Cortex, a Low-Profile Locking Plate With a Combination of Autologous Calcaneal Bone Graft and Demineralized Human Bone Matrix

Adult acquired flatfoot deformity encompasses deformities of the entire foot and ankle, with most clinical presentations comprising of a flexible planovalgus deformity and forefoot abduction. Numerous operative procedures have been proposed, and a lateral column–lengthening procedure is advocated to correct the forefoot abduction. Autologous iliac crest bone graft is routinely inserted into the opening-wedge osteotomy at the anterior calcaneum. Fixation methods are also variable with increasing use of locking plates to achieve stability at this osteotomy. Harvesting the iliac crest graft exposes the patient to significant donor site morbidity. We describe a modified lateral column–lengthening technique, leaving the medial calcaneum cortex intact, packing a combination of autologous calcaneal bone graft, and demineralized bone matrix into the osteotomy site, fixed with a low-profile locking plate. In the short term, our technique offers reduced rates of wound complications, symptomatic hardware, nonunion, and deformity recurrence when compared with published rates. Level of Evidence: Level IV, Case Series (retrospective).

Biomechanical Effects of Medializing Calcaneal Osteotomy on Bones and the Tissues Related to Adult-Acquired Flatfoot Deformity: A Computational Study

Medializing calcaneal osteotomy (MCO) is a flatfoot treatment in stages IIa–IIb. It is true that structural correction is well known, but stress changes in foot tissues have not been sufficiently studied to date. Our objective was to evaluate the stress generated by MCO in both hindfoot and forefoot bones and in some soft tissues that support the arch. A finite element foot model was employed, simulating some situations related to flatfoot development. Results show a higher stress concentration around the osteotomy region when MCO is used in patients with plantar fascia weakness. Additionally, the stress increase found in lateral metatarsals would be the explanation for the long-term pain reported by patients.

Evaluation of the heel external rotation test in soft tissue deficiencies associated with adult acquired flatfoot deformity (AAFD). A cadaver sectioning analysis.

To date, evaluation of the heel external rotation test has not been taken with respect to AAFD. Traditional 'gold standard' tests do not account for the contribution of the midfoot ligaments towards instability. These tests would be flawed as any midfoot instability may produce a false positive result. To evaluate the differential contribution of the spring, deltoid and other local ligaments in external rotation generated at the heel. Serial ligament sectioning was performed on 16 cadaveric specimens, with a 40N-external rotation force applied to the heel. These were divided into four groups with different sequences of ligament sectioning. Measurements of the total amount/range of external, tibiotalar and subtalar rotation were made. The deep component of the deltoid ligament (DD) was the main ligament influencing heel external rotation (P<0.05, in all cases), and acted primarily at the tibiotalar joint (87.9 %). The spring ligament (SL) influenced heel external rotation predominantly (91.2 %) at the subtalar joint (STJ). Greater than 20 degrees external rotation could only be achieved with DD sectioning. The interosseous (IO) and cervical (CL) ligaments did not significantly contribute to external rotation at either joint (P>0.05). Clinically relevant external rotation (>20 degrees) is solely attributable to DD failure in the presence of intact lateral ligaments (LL). This test may improve detection of DD instability and allow clinicians to subclassify patients with Stage 2 AAFD into those where DD may or may not be compromised.

Radiographic Outcomes of Titanium Augment vs Bone Graft in Lateral Column Lengthening for Adult-Acquired Flatfoot Deformity.

Lateral column lengthening (LCL) is a surgical procedure used to manage forefoot abduction and, in theory, also increases the longitudinal arch by plantarflexion of the first ray through tensioning the peroneus longus for patients with stage IIB adult acquired flatfoot deformity (AAFD). This procedure utilizes an opening wedge osteotomy of the calcaneus, which is then filled with autograft, allograft, or a porous metal wedge. The primary aim of this study was to compare the radiographic outcomes of these different bone substitutes following LCL for stage IIB AAFD. We conducted a retrospective review of all patients who underwent LCL from October 2008 until October 2018. Preoperative weightbearing radiographs, initial postoperative radiographs, and 1-year weightbearing radiographs were reviewed. The following radiographic measurements were recorded: incongruency angle, talonavicular coverage angle (TNCA), talar-first metatarsal angle (T-1MT), and calcaneal pitch. A total of 44 patients were included in our study. The mean age of the cohort was 54 (range, 18-74). The study cohort was divided into 2 groups. There were 17 (38.7%) patients who received a titanium metal wedge and 27 (61.5%) that received autograft or allograft. Patients that underwent LCL with the autograft/allograft group were significantly older (59 vs 47 years old, P = .006). Patients who underwent LCL with a titanium wedge had a significantly higher preoperative talonavicular angle (32 vs 27 degrees, P = .013). There were no significant differences in postoperative TNCA, incongruency angle, or calcaneal pitch at 6 months or 1 year. At 6 months and 1 year, no radiographic differences were found between autograft/allograft bone substitutes vs titanium wedge in LCL. Level III, retrospective cohort study.

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

BackgroundPopulation-level data describing patient characteristics and interventions used in surgical treatment of adult acquired flatfoot deformity (AAFD) is lacking. MethodsWe 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. Results625 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. ConclusionsPatients with AAFD have low health-related quality of life before surgery. Treatment in Sweden follows best-available evidence but regional variations exist. Level of evidenceIII

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.

Associated correction of forefoot alignment with hindfoot fusion for pes planovalgus deformity

BackgroundThe present study aimed to investigate changes in hallux alignment after corrective surgery for adult-acquired flatfoot deformity (AAFD). Patients and methodsThe present study retrospectively investigated the changes of hallux alignment in 37 feet (33 patients) which were treated with double or triple arthrodesis of the hindfoot for AAFD between 2015 and 2021 and could be followed up to one year postoperatively. ResultsHallux valgus (HV) angle significantly decreased by a mean 4.1° among the whole 37 subjects and by a mean 6.6° among the 24 subjects who had a preoperative HV angle of 15° or more. Those who had HV correction (HV angle correction ≥ 5°) demonstrated more near-normal postoperative alignment of the medial longitudinal arch and hindfoot than those without HV correction. ConclusionsHindfoot fusion for AAFD could improve preoperative HV deformity to some degree. HV correction was associated with proper realignment of the midfoot and hindfoot. Level of evidenceLevel IV; retrospective case series

Adult acquired flatfoot deformity: an update in classification

Adult acquired flatfoot deformity (AAFD) involves a complex spectrum of pathologies, arising primarily from failure of static restrains, leading to collapse of the medial longitudinal arch and further subsequent deformities in the foot. The landmark paper and classification by Johnson et al. proposed that pathology in the posterior tibial tendon (PTT) was key in the development of AAFD. Since then, the understanding of AAFD has evolved and advanced. Multiple structures aside from the PTT, such as the spring ligament, plantar fascia and deltoid ligament, have been identified to play a similarly key role in disease development and progression. Classification systems have also evolved to incorporate this new understanding. These include modifications to Johnson's classification (Myerson, Bluman) as well as new systems which aim to incorporate modern thinking, capture the wide spectrum of presentations or utilize modern advancements in imaging modalities. Current classification systems continue to aid understanding and management of AAFD, despite their increasing complexity. Future classifications should aim to provide a succinct way to describe and understand AAFD, as well as guiding prognosis and management.

Adult Acquired Flatfoot Deformity: A Narrative Review about Imaging Findings.

Adult acquired flatfoot deformity (AAFD) is a disorder caused by repetitive overloading, which leads to progressive posterior tibialis tendon (PTT) insufficiency. It mainly affects middle-aged women and occurs with foot pain, malalignment, and loss of function. After clinical examination, imaging plays a key role in the diagnosis and management of this pathology. Imaging allows confirmation of the diagnosis, monitoring of the disorder, outcome assessment and complication identification. Weight-bearing radiography of the foot and ankle are gold standard for the diagnosis of AAFD. Magnetic Resonance Imaging (MRI) is not routinely needed for the diagnosis; however, it can be used to evaluate the spring ligament and the degree of PTT damage which can help to guide surgical plans and management in patients with severe deformity. Ultrasonography (US) can be considered another helpful tool to evaluate the condition of the PTT and other soft-tissue structures. Computed Tomography (CT) provides enhanced, detailed visualization of the hindfoot, and it is useful both in the evaluation of bone abnormalities and in the accurate evaluation of measurements useful for diagnosis and post-surgical follow-up. Other state-of-the-art imaging examinations, like multiplanar weight-bearing imaging, are emerging as techniques for diagnosis and preoperative planning but are not yet standardized and their scope of application is not yet well defined. The aim of this review, performed through Pubmed and Web of Science databases, was to analyze the literature relating to the role of imaging in the diagnosis and treatment of AAFD.

Characteristics and Future Direction of Tibialis Posterior Tendinopathy Research: A Scoping Review.

Background and Objectives: Tibialis posterior tendon pathologies have been traditionally categorized into different stages of posterior tibial tendon dysfunction (PTTD), or adult acquired flatfoot deformity (AAFD), and more recently to progressive collapsing foot deformity (PCFD). The purpose of this scoping review is to synthesize and characterize literature on early stages of PTTD (previously known as Stage I and II), which we will describe as tibialis posterior tendinopathy (TPT). We aim to identify what is known about TPT, identify gaps in knowledge on the topics of TPT, and propose future research direction. Materials and Methods: We included 44 studies and categorized them into epidemiology, diagnosis, evaluation, biomechanics outcome measure, imaging, and nonsurgical treatment. Results: A majority of studies (86.4%, 38 of 44 studies) recruited patients with mean or median ages greater than 40. For studies that reported body mass index (BMI) of the patients, 81.5% had mean or median BMI meeting criteria for being overweight. All but two papers described study populations as predominantly or entirely female gender. Biomechanical studies characterized findings associated with TPT to include increased forefoot abduction and rearfoot eversion during gait cycle, weak hip and ankle performance, and poor balance. Research on non-surgical treatment focused on orthotics with evidence mostly limited to observational studies. The optimal exercise regimen for the management of TPT remains unclear due to the limited number of high-quality studies. Conclusions: More epidemiological studies from diverse patient populations are necessary to better understand prevalence, incidence, and risk factors for TPT. The lack of high-quality studies investigating nonsurgical treatment options is concerning because, regardless of coexisting foot deformity, the initial treatment for TPT is typically conservative. Additional studies comparing various exercise programs may help identify optimal exercise therapy, and investigation into further nonsurgical treatments is needed to optimize the management for TPT.

Translated article] Surgical treatment at adult acquired flatfoot stage IIB: Spring ligament repair

Background and aimsThe spring ligament has paramount role in supporting the arches and its fail causes the collapse of the medial longitudinal arc, inducing adult acquired flatfoot deformity. Our aim was to analyze the clinical and radiological outcomes of spring ligament repair and titanium wedges integration used in surgical osteotomies. Material and methodsWe performed a retrospective study of 23 cases with middle ages of 63, diagnosed with adult acquired flatfoot deformity stage IIB in RAM classification after ortho-prosthetic treatment failure, assessing the functional outcomes using the American Orthopedic Foot and Ankle Society scale and the radiological outcomes studying angles variation (talonavicular uncoverage, talo-first metatarsal angle and Meary axis). ResultsThe mean preoperative American Orthopedic Foot and Ankle Society score of the sample was 52±10 and the postoperative 88±6 (p<0.05). The radiological outcomes showed a statistically significant improvement. ConclusionSpring ligament repair associated to bone reconstruction offers large functional and radiological outcomes to adult acquired flatfoot deformity stage IIB treatment. Titanium wedges present an excellent bone integration.

Surgical Correction of Peritalar Subluxation and Subtalar Joint Articular Coverage Improves Patient- Reported Outcomes in Progressive Collapsing Foot Deformity

Category: Hindfoot; Ankle; Midfoot/Forefoot Introduction/Purpose: Optimization of articular joint coverage has been shown to decrease the progression of arthritic degeneration and to improve outcomes in patients with hip and shoulder pathologies. Progressive Collapsing Foot Deformity (PCFD), previously known as Adult-Acquired Flatfoot Deformity, has been demonstrated to advance with peritalar subluxation (PTS), progressively decreased articular coverage of the subtalar joint articular facets (anterior, middle, and posterior), as well as the development of sinus tarsi and subfibular impingements. Outcome assessment in PCFD has focused on improving conventional radiographic measurements such as the talus-first metatarsal angle and the hindfoot moment arm. This study aimed to evaluate improvements of PTS, subtalar joint articular coverage, and extra-articular impingement following PCFD joint-sparing surgical treatment, as well as the influence of these improvements in patient-reported outcomes. Methods: IRB-approved prospective comparative study. Adult PCFD patients that failed conservative treatment for three-months and underwent hindfoot joint-sparing surgical procedures by a single-surgeon were enrolled. Realignment soft-tissue and bony procedures performed were recorded. All patients underwent Weight Bearing CT (WBCT) preoperatively, and at the 3- and 12- months follow-up. Two observers performed traditional WBCT PCFD measurements. The foot bones were segmented, and distance measurements were performed along the entire 3D superior surface of the calcaneus, including the subtalar joint (SJ) articular facets (anterior, middle, and posterior), sinus tarsi and subfibular area. Color-coded coverage maps (CM) were calculated to grade the amount of articular joint coverage and extra-articular impingement. Patient Reported Outcomes (PROs) were recorded at all follow-up time-points. Pre- and postoperative measurements were compared by paired T-Tests/Wilcoxon and a Multivariate regression analysis was utilized to assess the influence of improvements of articular coverage and impingement in PROs. Results: Twenty patients were included (15F/5M), mean age, BMI, and follow-up of respectively 48.1 (22 to 72) years, 33.88 (23.8 to 46.8) kg/m2, and 13.2 (4 to 27) months. Significant improvements in all traditional PCFD WBCT measurements were noted postoperatively. Articular coverage (CM) of the SJ middle and anterior facets improved postoperatively by respectively 13.5% (p=0.02) and 78% (p=0.001). Similarly, improvement in sinus tarsi impingement, with a 69% decrease in sinus tarsi coverage was observed (p&lt;0.001). Significant PROs improvements were also noted, with Pain Catastrophizing Score (PCS) improving from 13.4 to 5.2 (p=0.0032) and the European Foot and Ankle Score (EFAS) from 6 to 8.5 (p=0.036). Improvements in PROs for PCS and EFAS were explained its majority by improvement in SJ articular coverage and sinus tarsi impingement, with R2 values of respectively 84% and 92% for PCS and EFAS. Conclusion: Peritalar subluxation (PTS) is an important marker of Progressive Collapsing Foot Deformity (PCFD). To the author's knowledge, this is the first time that 3D articular coverage maps were utilized to assess deformity correction following surgical treatment in PCFD. We found significant improvements in the subtalar joint (SJ) anterior and middle facet articular coverage as well as significantly decreased sinus tarsi and subfibular impingement. Most importantly, we found that PTS and SJ articular coverage improvements were the most important variables to influence Patient-Reported Outcomes. Three-dimensional evaluation of PTS and joint coverage can hopefully optimize treatment and improve outcomes in PCFD.

A novel implantable mechanism-based tendon transfer surgery for adult acquired flatfoot deformity: Evaluating feasibility in biomechanical simulation.

Adult acquired flatfoot deformity becomes permanent with stage III posterior tibialis tendon dysfunction and results in foot pain and difficulty walking and balancing. To prevent progression to stage III posterior tibialis tendon dysfunction when conservative treatment fails, a flexor digitorum longus to posterior tibialis tendon transfer is often conducted. However, since the flexor digitorum longus only has one-third the force-capability of the posterior tibialis, an osteotomy is typically also required. We propose the use of a novel implantable mechanism to replace the direct attachment of the tendon transfer with a sliding pulley to amplify the force transferred from the donor flexor digitorum longus to the foot arch. In this work, we created four OpenSim models of an arched foot, a flatfoot, a flatfoot with traditional tendon transfer, and a flatfoot with implant-modified tendon transfer. Paired with these models, we developed a forward dynamic simulation of the stance phase of gait that reproduces the medial/lateral distribution of vertical ground reaction forces. The simulation couples the use of a fixed tibia, moving ground plane methodology with simultaneous activation of nine extrinsic lower limb muscles. The arched foot and flatfoot models produced vertical ground reaction forces with the characteristic double-peak profile of gait, and the medial/lateral distribution of these forces compared well with the literature. The flatfoot model with implant-modified tendon transfer produced a 94.2% restoration of the medial/lateral distribution of vertical ground reaction forces generated by our arched foot model, which also represents a 2.1X improvement upon our tendon transfer model. This result demonstrates the feasibility of a pulley-like implant to improve functional outcomes for surgical treatment of adult acquired flatfoot deformity with ideal biomechanics in simulation. The real-world efficacy and feasibility of such a device will require further exploration of factors such as surgical variability, soft tissue interactions and healing response.

Tratamiento quirúrgico del pie plano valgo adquirido del adulto en estadio IIB: papel de la reparación del «spring ligament»

Background and aimsThe spring ligament has paramount role in supporting the arches and its fail causes the collapse of the medial longitudinal arc, inducing adult acquired flatfoot deformity. Our aim was to analyze the clinical and radiological outcomes of spring ligament repair and titanium wedges integration used in surgical osteotomies. Material and methodsWe performed a retrospective study of 23 cases with middle ages of 63, diagnosed with adult acquired flatfoot deformity stage IIB in RAM classification after ortho-prosthetic treatment failure, assessing the functional outcomes using the American Orthopedic Foot and Ankle Society scale and the radiological outcomes studying angles variation (talonavicular uncoverage, talo-first metatarsal angle and Meary axis). ResultsThe mean preoperative American Orthopedic Foot and Ankle Society score of the sample was 52±10 and the postoperative 88±6 (p<0.05). The radiological outcomes showed a statistically significant improvement. ConclusionSpring ligament repair associated to bone reconstruction offers large functional and radiological outcomes to adult acquired flatfoot deformity stage IIB treatment. Titanium wedges present an excellent bone integration.

A Novel Anatomic Reconstruction for Posterior Tibialis Tendon in Treatment of Flexible Adult-Acquired Flatfoot Deformity.

ObjectiveTo present a novel approach for the anatomic reconstruction of the posterior tibialis tendon (PTT) in restoring plantar insertions and evaluate its efficiency in treating flexible adult‐acquired flatfoot deformity (AAFD) caused by PTT dysfunction.MethodsFor AAFD treatment, a novel PTT reconstruction method was presented. The current study involved 16 patients, including three men, and 13 women, from August 2017 to July 2019. The mean age was 43.2 ± 15.1 years (21–64 years). The innovative PTT repair method was used on all patients. The treatment involved performing a traditional Flexor Digitorum Longus (FDL) transfer in the navicular tuberosity and suturing the plantar insertions to FDL as tension was applied to tighten the plantar structures of the foot. The results were retrospectively analyzed. The clinical outcome was assessed using the pain visual analogue scale (VAS), the satisfaction VAS, and the American Orthopedic Foot and Ankle Society ankle–hindfoot scale (AOFAS‐AH). Isokinetic testing was performed using a dynamometer at 60°/s and 120°/s for inversion/eversion and plantarflexion/dorsiflexion, respectively, to determine the mean peak torque. Radiographic measurements were employed to assess the outcomes.ResultsBone surgeries combined with the modified anatomic PTT reconstruction were performed on patients with medializing calcaneal osteotomy in 12 (75%) patients and subtalar joint fusion in four (25%) patients. The branch linking to the plantar insertions was detected in every case, with an average width of 3.5 ± 0.8 mm (3.1–4.3 mm). All patients were followed up for the mean of 16.8 ± 1.8 months (range, 15–20 months). The average postoperative functional scores, including pain VAS, satisfaction VAS, total AOFAS‐AH, and all AOFAS‐AH sub‐scales, steadily improved during the follow‐up. In the last follow‐up, isokinetic testing revealed no loss of plantarflexion strength (p = 0.350 and 0.098) and significant improvement in the inversion strength (p = 0.007 and 0.008) in the operated ankles at 60°/s and 120°/s. Radiographic outcomes, particularly the talar head uncovering, improved significantly after more than a year (p < 0.001 for all).ConclusionsThe novel technique for PTT reconstruction in restoring the plantar insertions serves as an effective procedure in treating AAFD caused by PTT dysfunction in terms of delivering a consistent improvement in ankle inversion strength, medial longitudinal arch restoring, and satisfactory clinical outcomes.