Middle Facet Research Articles

Total Arthroscopic Resection of the Talocalcaneal Coalition in Adults: Key Points of Surgical Technique.

Potential disadvantages of open technique for talocalcaneal coalition (TCC) include a risk of wound infection, opioid drug dependence, and prolonged hospitalization. The purpose of this study was to retrospectively evaluate the effectiveness and safety of endoscopic resection of the TCC. A retrospective study from June 2019 to February 2023was conducted on 16 consecutively admitted patients who were diagnosed by imaging to have TCC for whom conservative treatment had failed and who undergone arthroscopic resection. The mean age of this cohort was 31.56 ± 10.39 years (range, 16-57 years). The mean follow-up period was 38.93 ± 15.69 months (range, 11-59 months). The site of the coalition, comorbidities, satisfaction with treatment, visual analog scale (VAS), and American Orthopedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot scale scores were evaluated pre- and postoperatively. Preoperative magnetic resonance imaging (MRI) scans were used to categorize the coalition according to the Lim classification. Postoperative computed tomography (CT) scans were used to assess recurrence. The distribution of TCC cases according to the Lim classification was type I in one case, type II in four cases, and type III in 11 cases. The site of coalition involved the middle facets in seven patients, the posterior facets in three patients, and both the above sites in six patients. All patients underwent total arthroscopic resection of TCC. An auxiliary mini-incision was made for three patients due to serious tibial nerve compression. Radiographics showed that the coalition disappeared and pain was relieved postoperatively. The mean VAS score decreased from 4.31 ± 1.54 to 1.81 ± 0.98 points (p < 0.001). The mean AOFAS ankle-hindfoot score improved from 65.56 ± 5.82 to 87.31 ± 6.30 points (p < 0.001). Fifteen patients were satisfied with the procedure, and one patient experienced numbness after surgery. No recurrence was reported based on CT scan and clinical results up to the end of the study. Surgical reconstruction employing total arthroscopic resection of TCC can achieve significant functional and radiographic improvements and symptom relief in selected patients with TCC. Auxiliary mini-incisions were necessitated in complex situations.

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

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. 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. 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). 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.

Criteria for surgical decision-making in talocalcaneal tarsal coalitions

Assessment and management of talocalcaneal middle facet tarsal coalitions present a complex orthopedic challenge. Various studies have attempted to establish guidelines for surgical intervention based on coalition size and hindfoot alignment. Our paper reviews the historical focus on coalition size, suggesting instead that posterior facet health is a more appropriate consideration for surgical decision making. Additionally, we challenge the traditional method for evaluating hindfoot alignment and propose a more accurate evaluation method. This critical review intends to highlight flaws in historical literature, aiming to trigger a reevaluation of the criteria for surgical intervention in talocalcaneal tarsal coalitions and promote future research studies driven by data and scientifically validated methodologies. Level of evidenceV

Congruency of the TN Joint and Subtalar Joint Middle Facet Under With and Without Weightbearing: A Preliminary Report

Introduction/Purpose: Peritalar subluxation is a key feature of both flatfoot and cavovarus deformities. Our preliminary studies have found that on WBCT there is 20% subluxation of the middle facet of the subtalar joint in normal controls, and &gt;35% in patients with flexible flatfoot deformities; In the spherical talonavicular joint there is physiological uncovering of the talar head regardless of whether the joint is bearing weight or not, since the articular area of the talar head is 1.2 times of the navicular. We hypothesize that there may be a tendency to overestimate the pathological peritalar subluxation on both XR and WBCT. This study aimed to investigate the congruency of each peritalar joint using a weightbearing 3D CT scan remodeling technique. Methods: Five below-knee-amputated fresh frozen cadaveric feet were used (no history of surgery, trauma, arthritis, and deformities). Each specimen was CT scanned using both non-weightbearing and weightbearing protocols. Segmentation on Materialise Mimics software was used to remodel each peritalar bone three dimensionally. Congruency of the restored talonavicular joint and subtalar middle facet was evaluated in the GeoMagic. The total articular surface area for each bone was reconstructed, calculated and recorded. The articulation of each joint with or without weightbearing was restored for analyzing joint uncoverage. Paired t-test (P value ≤0.05) was used to compare the coverage % differences. Results: In the anterior and middle facets of the subtalar joint, There was 16.40% uncoverage of the calcaneus under non- weightbearing, and 30.68% of uncoverage under weightbearing; 17.94% uncoverage of the talus under non-weightbearing, and 24.89% of uncoverage under weightbearing. In the posterior facet of the subtalar joint, the total articular surface on the talus side (683.96±112.07 mm2) was 1.13 times larger than the calcaneus side (606.78±107.23 mm2). In the talonavicular joint, the total articular surface on the talus side (714.18±124.97 mm2) was 1.28 times larger than the navicular side (556.76±97.65 mm2). Conclusion: Our preliminary study in this group of normal cadaver feet has found that in both the talonavicular and middle facet of the subtalar joints, there is physiological uncovering or subluxation regardless of whether the joint is bearing weight or not. Further investigation with a larger sample size is in process.

Reaming for Tibiotalocalcaneal Nailing Removes Only 10% of the Ankle and Subtalar Joints.

Tibiotalocalcaneal (TTC) nailing in the setting of acute ankle trauma has become increasingly popular. No consensus exists as to whether formal joint preparation is necessary, although there is some concern that residual motion at unprepared joints may lead to implant loosening and/or breakage. The objective of this study was to quantify the proportion of tibiotalar and subtalar articular surface destruction that occurs during reaming for TTC nail fixation. Twelve cadaver lower extremities were procured. The specimens were pinned into neutral ankle and hindfoot alignment. A guidewire was inserted under fluoroscopy, followed by a 12-mm opening reamer. The specimens were then dissected, exposing the tibial plafond, talar dome, posterior facet of the talus, and posterior facet of the calcaneus. Images of each joint were obtained, and ImageJ software was used to calculate the total joint surface area and the area of articular destruction. The mean proportion of articular cartilage destruction was 9.3%, 10.3%, 8.9%, and 10.3% for the tibial plafond, talar dome, posterior facets of the talus, and posterior facets of the calcaneus, respectively. No joint destruction was observed in the middle facets of the subtalar joint. Reaming for TTC nail placement violates approximately 10% of each articular surface of the tibiotalar and subtalar joints. Retention of 90% of the articular surface may allow for residual motion at the joints and therefore potentially substantial stress on the implant. Formal joint preparation for the purposes of achieving fusion during TTC nail placement may be beneficial to prevent implant loosening or breakage.

Influence of Talar and Calcaneal Morphology on Subtalar Kinematics During Walking.

Cadaver biomechanical testing suggests that the morphology of articulating bones contributes to the stability of the joints and determines their kinematics; however, there are no studies examining the correlation between bone morphology and kinematics of the subtalar joint. The purpose of this study was to investigate the influence of talar and calcaneal morphology on subtalar kinematics during walking in healthy individuals. Forty ankles (20 healthy subjects, 10 women/10 men) were included. Participants walked at a self-selected pace while synchronized biplane radiographs of the hindfoot were acquired at 100 images per second during stance. Motion of the talus and calcaneus was tracked using a validated volumetric model-based tracking process, and subtalar kinematics were calculated. Talar and calcaneal morphology were evaluated using statistical shape modeling. Pearson correlation coefficients were used to assess the relationship between subtalar kinematics and the morphology features of the talus and calcaneus. This study found that a shallower posterior facet of the talus was correlated with the subtalar joint being in more dorsiflexion, more inversion, and more internal rotation, and higher curvature in the posterior facet was correlated with more inversion and eversion range of motion during stance. In the calcaneus, a gentler slope of the middle facet was correlated with greater subtalar inversion. The morphology of the posterior facet of the talus was found to a primary factor driving multiplanar subtalar joint kinematics during the stance phase of gait. This new knowledge relating form and function in the hindfoot may assist in identifying individuals susceptible to subtalar instability and in improving implant design to achieve desired kinematics after surgery.

Middle Facet Tarsal Coalition in a National Collegiate Athletic Association Basketball Athlete: An Exploration Clinical Case Report

The patient is a 22-year-old female basketball player initially diagnosed with a calcaneal fracture. Five months after the pain began, the patient was referred to a foot and ankle surgeon and diagnosed with middle facet tarsal coalition. The patient received one X-ray-guided subtalar steroid injection and two platelet-rich plasma injections to aid in pain relief while completing her senior year of collegiate basketball. She elected to end her senior season early to have the recommended subtalar fusion surgery. The surgery ended her basketball career but provided pain-free activities of daily living. This case presents unique components compared with available literature on how injury presentation in adult populations can complicate a timely and accurate initial diagnosis. This case is also unique because despite conservative efforts, a surgical fusion was required to optimize pain and function during activities of daily living.

Relationship Between Obesity and Medial Longitudinal Arch Bowing.

There have been reports about the association between obesity and the medial longitudinal arch (MLA) of foot. The purpose of this study is to investigate the change of various parameters related to the MLA according to obesity classification severity by the World Health Organization using weightbearing computed tomography (WBCT). WBCT data of the noninvolved side of patients presenting with unilateral foot and ankle problems or healthy candidates from September 2014 to October 2022 were extracted from a single referral hospital. Forty-four cases in each of 5 obesity classes were selected sequentially. Two orthopaedic surgeons measured foot and ankle offset, forefoot arch angle (FAA), hindfoot moment arm, percentage of uncoverage of the middle facet of the subtalar joint, talonavicular angle (TNA), navicular-medial cuneiform angle, medial cuneiform-first metatarsal angle, talus-first metatarsal angle (TMT1A), first tarsometatarsal subluxation (TMT1S), talonavicular coverage angle, navicular floor distance (NFD), and NFD per height. Positive values indicate plantar collapse. Intra- and interobserver reliabilities were assessed using intraclass correlation coefficients. One-way analysis of variance tests were performed for parametric data with equal variances, and Welch's test for unequal variances. Kruskal-Wallis test was performed for nonparametric data. Post hoc analysis was performed for statistically significant parameters. Correlation analysis between body mass index (BMI) and 12 parameters were performed using Pearson test. Intraobserver and interobserver reliability were excellent, except for TMT1S. The TNA and TMT1A showed a statistically significant difference. FAA (r = -0.2), TNA (r = 0.182), TMT1A (r = 0.296), and NFD (r = -0.173) showed a statistically significant correlation with BMI. In nonsymptomatic feet, we found that the talonavicular joint, as measured by the TNA, to be influenced by obesity classification. Obesity and increased BMI was associated with a negative influence on the MLA. Level III, retrospective cohort study.

Evaluation of Automated Coverage and Distance Mapping Selections to Improve Reliability and Clinical Utility of 3D Weightbearing CT Assessments

Category: Other; Hindfoot Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a complex three-dimensional (3D) deformity where adjacent structures may adopt subtle differences in positioning that result in increased contact or subluxation. Recent studies have highlighted the need for and utility of 3D analyses in PCFD using weightbearing CT (WBCT) and bone segmentation. Beyond the limitations of triplanar imaging, 3D distance and coverage mapping analyses have further highlighted key regional differences like sinus tarsi narrowing ahead of impingement and early middle facet uncoverage ahead of collapse. However, these analyses rely upon manual identification of subregions hindering the utility of 3D mapping clinically. The objective of this study was to compare an automated selection process with manual selections in the context of subtalar regional distance and coverage maps in PCFD. Methods: In this IRB-approved retrospective study, WBCT data of 20 consecutive patients with flexible PCFD and 10 controls were analyzed. Subregions of the peritalar surface (middle and posterior facets of the calcaneus and talus; sinus tarsi area) were manually selected by two experts on manually generated bone surfaces of all 30 feet. An automated algorithm for selecting coverage area was applied to identify the same regions on the semi-automatically generated bones (Figure). A 3D distance mapping (DM) technique was used to create coverage maps (CMs) across the entire peritalar surface where areas with distances less than 4mm were defined as covered. DM and CM percentages were compared using intra-class correlations and t-tests between PCFD and control groups. The Sørensen–Dice index, or Dice coefficient, was used for comparisons of selections on the semi-automated surfaces to evaluate reproducibility of expert selections. Results: The automated process produced identical selections resulting in perfect intra-method ICCs of 1.00 for all regions and Dice coefficients of 1.00. The average Dice coefficient for all manual selections was 0.903 (range: 0.865-0.935) indicating that observers were able to reliably select the same regions with 90% overlap. When assessing reliability of manual selections, intra- observer ICCs ranged from 0.41-0.92 while inter-observer ICCs ranged from 0.47-0.99 were found. Despite strong significant correlations, average coverage was significantly lower in the sinus tarsi region of the automated selections vs the manual selections (34.3±16.8% vs 23.1±12.7%, p&lt; 0.005). However, mean distances in each region were not significantly different in the middle facet or the sinus tarsi regions (p=0.323, p=0.095, respectively). Conclusion: Understanding of the complex 3D deformities that constitute PCFD requires sensitive and reproducible measures. Fully automated 3D assessments of coverage and bone relations can help improve understanding these deformities aiding in diagnosis, staging, and objective evaluation of treatment effects. Prior work with this method has specifically identified the middle facet and sinus tarsi regions as being of particular importance. Compared to manual selections, these regions were well identified by the automated process. This represents a major step toward viable use of fully automated 3D coverage and distance mapping when evaluating PCFD patients.

Assessment of Changes in Hindfoot Alignment of Total Ankle Arthroplasty for Ankle Osteoarthritis on Weightbearing Subtalar X-ray View.

Recovering normal hindfoot alignment and correcting deformity of the ankle joint following total ankle arthroplasty (TAA) in osteoarthritis (OA) is essential for improving clinical outcomes and increasing long-term survival. We aim to evaluate hindfoot alignment following standard TAA compared to TAA with a total talar prosthesis ("combined TAA") in varus-type OA patients. This retrospective study was conducted between 2010 and 2022. We included 27 patients (30 feet) who underwent standard TAA and 19 patients (22 feet) who underwent combined TAA. Hindfoot alignment at the subtalar joint was measured by weightbearing subtalar radiographic view before and after surgery. In the standard TAA, the angle between the tibial shaft axis and the articular surface of the talar dome joint (TTS) changed from 75 to 87 degrees (P < .01), the angle between the tibial axis and the surface on the middle facet (TMC) from 89 to 94 degrees (P < .01), and the angle between the tibial axis and the surface on the posterior facet (TPC) from 80 to 84 degrees (P < .01). The angle between the articular surface of the talar dome and the posterior facet of the calcaneus (SIA) decreased from 4.7 to -2.5 degrees (P < .01). In the combined TAA, TTS angle changed from 77 to 88 degrees (P < .01), TMC angle from 93 to 101 degrees (P < .01), TPC angle from 84 to 90 degrees (P < .05), and SIA from 6.6 to 2.1 degrees (P < .01). Varus deviation to the subtalar joint (TMC, TPC) significantly improved postoperatively in both groups. However, TPC was smaller than TTS and SIA was negative in standard TAA, and TPC was larger than TTS and SIA was positive in combined TAA. The amount of correction of the subtalar joint differed depending on the ligament dissection of the subtalar joint and shape of the talar component. Level III, retrospective cohort study.

Measurements and Protocols Used for Weight-Bearing Cone-Beam CT Scans for Evaluating the Alignment of the Foot and Ankle: A Systematic Literature Review

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Weight bearing CT has been widely used recently to provide detailed 3D information of the foot and ankle. Orthopedic surgeons have been exposed to this new technology, but do not have the equivalent tools to use to explore it. A lot of metrics were directly borrowed from plain radiographic imaging, while some new parameters were developed using traditional axes and angular concepts but on only one specific WBCT view out of hundreds of scans. Some metrics used similar measurement concepts, but on 3D reconstructed bones, while a few new parameters were introduced based on semi 3D and 3D thinking. Small sample sizes, obscure inclusion/exclusion criteria, and skewed validation methods are noted, and a thorough review of WBCT-based measurements used in foot and ankle is warranted. Methods: A literature search was conducted in two databases: PubMed (MEDLINE) and EMBASE (Elsevier). The main search terms and logics were: ((foot) OR (ankle) OR (hindfoot) OR (midfoot) OR (forefoot)) AND ((WBCT) OR (Weightbearing CT) OR (Cone beam CT scan) OR (PedCAT)). A longer string of key words was utilized to further narrow down the results to WBCT imaging associated with foot and ankle pathologies. The terms were expanded using the MeSH and Emtree expansion features of PubMed and EMBASE, respectively. All articles were reviewed by two independent senior foot and ankle surgeons based on pre-designed exclusion criteria. Off-topic articles were removed, and remaining articles were categorized based on measurement techniques. All articles were managed using Zotero. (Figure 1) Results: A total of 216 articles were selected for retrieval and further organized by measurement techniques. Seven groups were set by the type of the methodology used. Among them, 123 studies utilized traditional 2D measurement parameters (eg, hindfoot moment arm, Meary’s angle, talonavicular uncoverage, hallux valgus angle, etc.), 8 introduced new parameters but based on 2D axial/angular concepts (eg, middle facet subluxation percentage and angle), 22 used semi-automated 3D measurement techniques (3D segmentation + 2D axial and angular methods), 19 using semi-3D measurement techniques (Foot and Ankle Offset), 29 measured real 3D parameters (volume evaluation in the syndesmosis and Lisfranc joints, distance mapping), 3 morphological studies used 3D segmentation and sphere fitting. The advantages and disadvantages of each type of measurement were carefully examined and explored. Conclusion: 3D imaging measurements with WBCT appear to be highly variegated. Axial and angular measurements do not apply well to irregular bones and there is a low reproducibility in 3D scenarios. Although inter- and intraobserver reproducibility scores have been reported in multiple studies, they were only part of the validation system that should be done. A high correlation between parameters such as 2D and 3D hindfoot angles has been reported, but debate remains as to whether one method of measurement is more accurate than the other. Furthermore, variations in analytical methods warrant a more uniformly defined coordinate or anatomical system.

Outcomes of the Bone-Block Lapidus Arthrodesis (LapiCotton) in the Treatment of the Collapsed Foot

Category: Midfoot/Forefoot; Bunion Introduction/Purpose: Progressive collapsing foot deformity (PCFD), Hallux Valgus (HV), and Midfoot Arthritis (MA) are diseases that benefit from the Lapidus procedure due to its capability to provide a stable medial column while correcting the underlying deformity. However, the technique does not go without complications. First metatarsal shortening/dorsiflexion are not uncommon, which could be exacerbated by local anatomy/revision surgery settings. Restoring length and sagittal plane position (plantarflexion) of the first ray when treating these pathologies is paramount. Performing a primary distraction and plantarflexion fusion with an allograft wedge (LapiCotton) has been advocated in the literature, potentially allowing improved deformity correction, but with the risk of increased non-union rate. The objective of this study was to report medium-term follow-up results of the LapiCotton in patients with collapsed feet. Methods: This IRB-approved comparative prospective study assessed patients diagnosed with PCFD, HV, and MA undergoing a Lapidus bone-block fusion (LapiCotton) between August 2020 and November 2022. All patients were operated on by a single fellowship-trained foot and ankle surgeon after clinical evaluation and a weight-bearing computed tomography (WBCT). After adequate joint preparation and trials, a Lapidus pre-shaped wedge allograft was placed and fixed using available implants. Adjunctive procedures were carried out as needed. Patients were kept non-weight bearing for six weeks and followed clinically, performing a WBCT at three months and subsequent follow-up. Non-Union and complications were documented. Bone healing was determined by at least 50% of bone trabeculae crossing both graft interfaces at the WBCT. Forefoot arch angle (FFA), Meary’s angle, talonavicular coverage angle (TNCA), middle facet subluxation (MFS), and foot and ankle offset (FAO) were also obtained. Two fellowship-trained readers performed all assessments. P-values &gt;0.05 were considered significant. Results: Fifty-eight patients (60 feet) were included, mean age 53.87 (range:18-77)/BMI 31.70 (SD:7.96). Twenty-four PCFD, 19 HV, and 17 MA had an average 15.47 months (4-31) follow-up. Cuneiform-Post implants were used in 62%, plates/screws in 25%, and Lapidus nails in 13%. Median allograft size was 9mm (mode:8mm,5-19mm). Minor complications were observed in 3% (two superficial dehiscences) and major in 7% (three deep infections [5%], and one EHL contracture [2%]). Healing at the 3-month WBCT occurred in 94.8% and only in 66% at the most-recent WBCT (mean:11.08 months; 6-20). The clinical non-union rate demanding reoperation was eight clinical non-unions 13%. Mean FFA (pre:6.89,SD:6.63; postop:14.21,SD:5.48; p&lt; 0.001), Meary (pre:15.17,SD:8.12; postop:6.31,SD:5.61; p&lt; 0.001), TNCA (pre:26.75,SD:11.77; postop:11.59,SD:7.91; p&lt; 0.001), MFS (pre:36.3,SD:26; postop:23.49,SD:17.35; p&lt; 0.001), and FAO (pre:6.71,SD:5.81; postop:2.2,SD:4.33; p&lt; 0.001) improved after the interventions. Conclusion: Although the Lapidus bone-block arthrodesis (LapiCotton) restored many of the markers associated with foot collapse and alignment, non-union rated was noted in 13% what is on the top range of non-union rates reported in the literature for Lapidus arthrodesis. The use of allograft wedges in the fusion site probably explains our findings. The fact that the sample was heterogeneous and composed of considerably severe deformities should also be considered. Also, important to highlight that WBCT findings of fusion site healing was initially 94% at 3-months and only 66% at most recent follow-up). Additional studies and longer-term follow up are needed.

Prevalence of Progressive Collapsing Foot Deformity in Hallux Valgus Patients

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) and progressive collapsing foot deformity (PCFD) are very common foot and ankle conditions in the adult population. Both could potentially disrupt the tripod construct of the foot which leads to chronic pain and arthritis. Several procedures were described to address HV deformity depending on deformity characteristics. PCFD could alter the management plan for HV if they occur simultaneously. The aim of this study was to detect the prevalence of PCFD in HV patients and study the frequency of individual PCFD classes. Methods: In this retrospective IRB approved study, patients &gt; 18 years old who were evaluated for symptomatic hallux valgus and had a weight bearing computed tomography (WBCT) imaging were included. Patients were considered for further analysis if they have a hallux valgus angle (HVA) &gt; 15° or inter-metatarsal angle (IMA) &gt; 9°. All relevant demographic data were extracted. Two fellowship trained foot and ankle orthopaedic surgeon measured the following parameters: foot and ankle offset (FAO%) (Class A), talo-navicular coverage angle (TNCA) (Class B), Meary’s angle (Class C) and middle facet subluxation (MFS%) (Class D). Cases that showed FAO% &gt; 4.6% and MFS% &gt; 28.7% were diagnosed as PCFD. The prevalence of PCFD classes (A,B,C and D) was calculated using threshold values for its respective radiographic marker. Descriptive statistics were performed. Results: Thirty-four cases were included. 16 cases were females (46.06%) and 16 (46.06%) were right side. The average age was 52.51 years (SD ± 17.75), the average BMI was 30.14 (SD ± 7.15). The average HVA was 26.82 (SD ± 9.98) and the average IMA was 15.41 (SD ± 3.53). 13 patients (38.24%) had MFS% and FAO% above the threshold values. The average FAO was 4.75% (SD ± 4.92) and the average MFS was 29.17% (SD ± 15.89). Prevalence of Class A (FAO%) was 20 (58.82%), Class B (TNCA) was 12 (35.29%), Class C (Meary’s angle) was 15 (44.12%) and Class D (MFS%) was 16 (47.06%). Conclusion: Progressive collapsing foot deformity is prevalent in the hallux valgus population (38.24%). Class C which indicates medial column instability was prevalent in 44.12% of the cases. Given this high prevalence of PCFD, we believe that in addition to the classic hallux valgus parameters, PCFD classes evaluation could favor a surgical approach over another such as first tarsometatarsal joint procedures over isolated distal first metatarsal procedures to correct the HV deformity and simultaneously halt PCFD progression.

How Much Subtalar and Ankle Joint Surface are Actually Destroyed when Reaming for Tibiotalocalcaneal (TTC) Nailing? A Cadaveric Study

Category: Ankle; Trauma Introduction/Purpose: Tibiotalocalcaneal (TTC) nailing in the setting of acute ankle trauma has become increasingly popular over the last decade, with expanding indications. Potential advantages of TTC nailing include: less soft tissue dissection, decreased wound burden, and earlier weightbearing. No consensus exists as to whether formal joint preparation is necessary, and at one or both joints. While some argue that joint preparation is not necessary due to inherent joint destruction from the injury and reaming during TTC nailing, others advocate for preparation to facilitate fusion and ensure no further motion occurs at the joint which could lead to nonunion and/or hardware failure. The purpose of this study was to quantify the proportion of ankle and subtalar joint articular surface destruction associated with reaming for TTC nail fixation. Methods: Twelve cadaver feet from 6 specimens were procured. The specimens were reduced and pinned into neutral ankle dorsiflexion and neutral hindfoot alignment. Prior to reaming, each specimen was secured in a simulated supine position. Per standard TTC nailing technique, a 3.0 millimeter (mm) guide wire was inserted under fluoroscopy, retrograde from the calcaneus, through the talus, and into the tibia, followed by a 12mm opening reamer. The specimens were then dissected, exposing the tibial plafond (TP), talar dome (TD), posterior facet of the talus (PFT), and posterior facet of the calcaneus (PFC). Clinical images of each joint were obtained at an angle of 90 degrees and 12 centimeters (cm) from the joint surface. The images were processed using the ImageJ software platform. The total joint surface area, area of articular destruction, and the remaining joint surface area were calculated. The percentage of joint destruction associated with reaming was then calculated. Results: The mean surface area values and percentages of articular surface destruction are summarized in Table 1. The mean surface area (cm2) after reaming was 11.82, 13.70, 9.23, and 7.79 for the TP, TD, PFT, PFC, respectively. The percentage of articular cartilage destruction was 9.32%, 10.33%, 8.89%, and 10.28% for the TP, TD, PFT, PFC, respectively. No joint destruction was observed in the middle facets of the subtalar joint. Conclusion: This study demonstrates that reaming for TTC nail placement involves only a small portion (roughly 8-10%) of each of the articular surfaces of the ankle and subtalar joints. Violation of the middle facet of the subtalar joint did not occur. These results suggest that a significant portion of hindfoot articular surface remains after reaming for TTC nail. Formal joint preparation may be beneficial to aid with fusion after TTC nail placement, particularly when used in younger, more active individuals who sustain hindfoot and ankle trauma.

Topography and Morphometrics of the Cartilage Surfaces in the Peritalar Joints

Category: Hindfoot; Ankle Introduction/Purpose: Recent studies have highlighted the important role of peritalar joint congruence in maintaining the alignment of the hindfoot. Peritalar subluxation is associated with a variety of pathological deformities including flatfoot, cavovarus foot, clubfoot, as well as foot and ankle stress fractures. To date, studies of peritalar joint congruence have all been performed using either XR, WBCT based direct measurements, or 3D segmentation and analysis. However, none of these techniques can demonstrate the cartilage location nor disruption, nor the exact location of the articulation on the bone surface. Data bias caused by the limitations of these study methodologies is therefore inevitable. This study used 3D surface mapping to assess morphometrics of the cartilage surfaces of the peritalar joints. Methods: 11 fresh-frozen cadaveric feet without trauma nor surgery or significant deformities were dissected to expose the calcaneus, cuboid, talus, and navicular bones, and the articular surfaces. Surface mapping of the articular surfaces and the two bones was completed using an Artec Space Spider 3D scanner and Mmics. Further digital analysis was completed using GeoMagic Studio 10. T-test was used for statistical comparisons, with p&lt; 0.05 as statistically significantly different. Results: Detailed information of the articular surfaces is summarized in Table 1. The average articular area on both sides of the joint matched each other well in the posterior facet of the subtalar joint (4% difference), and calcaneocuboid joint (3% difference) without significant statistical difference, but not in the anterior &amp; middle facets of the subtalar joint, nor the talonavicular joint. In the anterior &amp; middle facets of the subtalar joint, the cartilage articular area on the talar side was 124% of that on the calcaneus (p &lt; 0.05), and in the talonavicular joint the cartilage articular area on the navicular was 138% of that on the talus (p &lt; 0.05). Conclusion: The cartilage articular surfaces in certain peritalar joints do not match its opposing surface in size. In the talonavicular joint, it is easy to understand since area of the socket must be much smaller than that of the ball in order for the joint to glide and rotate. There must be functional reasons for this phenomenon to happen in the anterior and middle facets of the subtalar joint, which need further investigation. This study shows that the extent of subluxation of the peritalar joints may be physiological and should not necessarily be considered as pathological.

Conservative Treatment with Arch Support Inflatable Ankle-Foot Orthosis Does Not Correct Progressive Collapsing Foot Deformity: A Prospective Comparative and Controlled Study

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Progressive Collapsing Foot Deformity (PCFD) can present with independent deformities, characterized by five classes: hindfoot valgus (Class A), midfoot abduction (Class B), forefoot varus (Class C), Peritalar Subluxation (PTS) (Class D) and ankle valgus (Class E). Conservative treatment includes the use of corrective insoles and orthotics. Arch support inflatable Ankle-Foot orthoses (IAFO) can help control symptoms in PCFD patients. However, the ability of IAFOs to correct deformities in PCFD is unknown. The aim of this prospective comparative and controlled study was to assess the ability of arch support IAFOs to correct 3D overall PCFD alignment as well as the five different PCFD classes independently. We hypothesized that IAFOs would correct PCFD 3D overall alignment as well as the five independent classes of deformity. Methods: After IRB approval, we enrolled 24 symptomatic PCFD and 24 controls matched on age, sex, and BMI. Flexible PCFD patients and controls were scanned using Weight-Bearing CT (WBCT) with and without an arch support IAFO. The Foot and Ankle Offset (FAO) was used to assess the 3D foot overall alignment. We measured the Hindfoot moment arm (HMA, Class A), the Talonavicular coverage angle (TNCA, Class B), the Meary’s angle and medial cuneiform-to-floor distance (C1-floor) for the Class C and the middle facet uncoverage (MFunco, Class D). No Class E patients were included. Measurements were performed by two fellowship-trained surgeons. A power-analysis hypothesizing that IAFOs would be two times less efficient than the PCFD surgery in correcting the FAO, the requisite number of subjects was 24 per group. Data normality was assessed by Shapiro-Wilk test. Comparisons used normality based paired T-tests or paired-Wilcoxon tests. P-values &lt; 0.05 were considered significant. Results: PCFD measurements performed in controls were all significantly less pronounced than unbraced PCFD patients, confirming the presence of collapse (ps &lt; 0.0001). Comparing PCFD without and with IAFO, the FAO did not show significant improvement (respectively 6.6+/-3.7% vs 5.5+/-4.2%, p=0.101). The HMA (8.8+/-5.8 vs 8.1+/-5.8, p=0.66), the TNCA (24.2+/-10.6 vs 21.9+/-9.7, p=0.44) and the MFunco (37+/-12% vs 31+/-18%, p=0.17) also did not portray significant improvements when applying the IAFOs. The Meary’s angle (17.6+/-7.2 vs 10.8+/-7.3, p=0.002) and C1-floor (17.2+/-3.3mm vs 24.1+/-5.3mm, p&lt; 0.001) were the only to improve significantly with use of IAFOs. When comparing braced PCFD and controls, the only measurement that improved to normal values, similar to controls, in braced PCFD was the C1-floor (24.1+/-5.3mm in PCFD with IAFO vs 25.7+/- 5.4mm in controls, p=0.31). Conclusion: In this prospective comparative and controlled study, we found that arch support IAFOs was not able to correct overall 3D deformity and most of the specific classes in PCFD. The orthosis did not improve hindfoot valgus (Class A), midfoot abduction (Class B) or peritalar subluxation (Class D) in PCFD. The only deformity pattern to improve with the use of IAFOs was the medial longitudinal arch height (Class C). These improvements were expected by the presence of the inflatable bladder of the IAFO on the plantar aspect of the foot, pushing the longitunal arch up but not correcting the entire PCFD.

Comparing Symptomatic and Asymptomatic Flatfeet Using Known Markers of Progressive Collapsing Foot Deformity (PCFD): A Case Control Study

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Flattening of the longitudinal arch of the foot (Flatfoot) can represent a normal spectrum of foot morphology and alignment. The issue comes when the foot is collapsing progressively, what is now termed Progressive Collapsing Foot Deformity (PCFD). Literature on asymptomatic flatfoot is scarce since asymptomatic patients do not seek medical attention. Alignment differences between asymptomatic flatfoot and PCFD have not been established and might represent a key-step in understanding predictors of PCFD. The objective of this prospective study was to compare established PCFD measures in a cohort of asymptomatic flatfoot, PCFD patients and healthy controls. We hypothesized that asymptomatic flatfeet alignment would differ from both symptomatic PCFD patients and healthy controls. Methods: In this prospective comparative study, patients with asymptomatic flatfeet were recruited to undergo a weight-bearing CT (WBCT) scan. This cohort (22 feet, 10 males, 12 females) was compared to two other prospective cohorts (22 symptomatic PCFD and 22 healthy controls). Along with demographic data, PCFD measurements performed include Foot and Ankle Offset (FAO), Forefoot Arch Angle (FAA), Middle Facet Uncoverage, and the Transverse Arch Plantar (TAP) angle. Normality of variables was assessed using the Shapiro-Wilk test. Chi-squared or analysis of variance (ANOVA) test was performed to compare each parameter between the three groups. A post-hoc Bonferroni test was then performed to assess significance between each group pairing. P-values of &gt;0.05 were considered significant. Results: All three groups were comparable on BMI (p=0.10), Age (p=0.75) and Gender (p=0.78). All measurements taken differed significantly between the symptomatic PCFD and healthy controls (Table 1). FAO was significantly different between controls vs asymptomatic (p &lt; 0.001) and asymptomatic vs symptomatic (p &lt; 0.001). FAA was also significantly different between asymptomatic and both symptomatic (p=0.001) and control groups (p=0.001). Middle facet uncoverage differed between the asymptomatic and control group (p=0.001) but the asymptomatic and symptomatic group were similar (p=0.106). While the TAP angle was significantly different between asymptotic and symptomatic groups (p=0.013), the asymptomatic and control groups failed to reach significance (p=0.061) (Table 1). On average, deformity measurements for asymptomatic flatfeet were in between the values for healthy controls and symptomatic PCFD (Figures 1-3). Conclusion: To our knowledge this is the first prospective study to compare healthy controls, asymptomatic flatfoot and symptomatic PCFD patients. We observed that asymptomatic flatfoot patients usually had measurements of PCFD that would fall in between normal alignment asymptomatic controls and symptomatic PCFD patients. Further, the asymptomatic group differed significantly from both other groups on every measure but two. Our data supports the idea that asymptomatic flatfoot should be considered a risk factor for Progressive Collapsing Foot Deformity. Our data can hopefully shine light in finding predictive markers for the development of PCFD.

Three-Dimensional Distance Mapping to Identify Safe Zones for Lateral Column Lengthening.

Evans (E-LCL) and Hintermann LCL (H-LCL) lateral column lengthening osteotomies are standard surgical solutions for flexible, progressive collapsing feet. E-LCL is performed between the anterior and middle facets and endangers specific os calcis subtalar joint (OCST) subtypes without distinct facets. H-LCL is oriented between the posterior and middle facets and should be suitable for all OCSTs. Both osteotomies are associated with increased subtalar osteoarthritis, indicating iatrogenic damage. Distance mapping (DM) enables visualization of the relative distance between 2 articular surfaces represented by color patterns. This study aims to measure the safe zones for LCL using 3-dimensional (3D) models and DM; we hypothesize that it could be measured with high reproducibility. Two raters categorized 200 feet across 134 patients into OCSTs based on the Bruckner classification. Four angles were measured independently. The proximal and distal extents of the posterior safe zone (PSZ) angles were determined for H-LCL osteotomies; similarly, the proximal and distal extents of the anterior safe zone (ASZ) angles were identified for E-LCL osteotomies. Consequently, the surface available for safe osteotomies were calculated. An interclass correlation was used to assess the agreement between the 2 raters. Additionally, analysis of variance and Mann-Whitney U test were used to compare the safe zones between OCSTs. The mean proximal and distal extents of the PSZ angles were 68 ± 7 and 75 ± 5 degrees from a line parallel to the lateral border of the calcaneus, respectively, and the proximal and distal extent of the ASZ angles were 89 ± 6 and 95 ± 5 degrees, respectively. There were no statistically significant differences between the OCSTs. Two raters measured the angles with good to excellent interrater and intrarater agreement. In 18 cases, we were unable to plan for H-LCL or E-LCL osteotomies. Distance mapping could be used to measure the safe zone, tailor a preoperative plan, and potentially reduce the risk for iatrogenic damage in LCL. 3D models and DM can increase the reliability of preoperative plans in bones with complex 3D structures. Level III, retrospective comparative study.

Strain distribution in the bursal rotator cuff based on whole-muscle and muscle subregion-specific loading: A cadaveric study.

Rotator cuff (RC) tears are common injuries leading to significant dysfunction of the shoulder. Rotator cuff tears alter tension and strain in muscles and tendons. Anatomical studies demonstrated that rotator cuff muscles are comprised of anatomical subregions. However, the strain distribution within the rotator cuff tendons generated from the tension from each anatomical subregion is unknown. We hypothesized that subregions would present distinct 3-dimensional (3D) strain distributions within the rotator cuff tendons, and that the anatomical insertion configuration of the supraspinatus (SSP) and infraspinatus (ISP) tendons might dictate strain, thus tension, transmission. 3D-strains in the bursal side of the SSP and ISP tendons of eight fresh-frozen cadaveric intact shoulders were obtained by applying tension on the whole SSP and ISP muscles, and on their subregions using an MTS system. Strains in the anterior region of the SSP tendon were higher than in the posterior region with whole-SSPanterior-region (p < 0.05) and whole-SSP muscle loading. Higher strains were observed in the inferior half of the ISP tendon with whole-ISP muscle (p < 0.05), middle-subregion (p < 0.01), and superior-subregion (p < 0.05) loading. Tension generating from the posterior-region of the SSP was primarily transmitted to the middle facet via an overlap between the SSP and ISP tendons insertions, while the anterior-region mainly distributed its tension into the superior facet. Tension generating from the middle and superior-regions of the ISP was distributed into the inferior portion of the ISP tendon. These results emphasize the importance of the distinct anatomical subregions of the SSP and ISP muscles in distributing the tension to the tendons.

Decreased Peritalar Subluxation in Progressive Collapsing Foot Deformity with Ankle Valgus Tilting.

Middle facet subluxation (MFS) has been established as an early indicator of peritalar subluxation. However, when progressive collapsing foot deformity (PCFD) affects the ankle leading to a valgus talar tilt (Class E), structures and anatomic relationships distal to the ankle joint may be affected. Therefore, this study aimed to assess radiographic parameters of peritalar subluxation in patients with PCFD who either did or did not have a valgus ankle. Our hypothesis was that these parameters would differ in Class E patients, upsetting their capability to quantify deformity. We performed a prospective comparative study utilizing weight-bearing computed tomography (WBCT) images of 21 feet with PCFD and with valgus of the ankle and 64 with flexible PCFD without ankle involvement. Parameters including MFS, the medial cuneiform-to-floor distance, the forefoot arch angle, the talonavicular coverage angle, the hindfoot moment arm (HMA), the foot-ankle offset (FAO), and the talar tilt angle (TTA) were measured and compared. Variables that influence the presence of ankle valgus and overall alignment were assessed by multivariable regression models. Patients with PCFD and ankle valgus demonstrated a higher mean HMA (20.79 mm [95% confidence interval (CI), 17.56 to 24.02 mm] versus 8.94 mm [95% CI, 7.09 to 10.79 mm]), FAO (14.89% [95% CI, 12.51% to 17.26%] versus 6.32% [95% CI, 4.96% to 7.68%]) and TTA (95% CI, 17.10° [14.75° to 19.46°] versus 2.30° [95% CI, 0.94° to 3.65°]) and lower mean MFS (21.84% [95% CI, 15.04% to 28.63%] versus 38.45% [95% CI, 34.55% to 42.34%]) compared with the group without ankle valgus (p < 0.0001 for all). The FAO was influenced by MFS in the group without ankle valgus (p <0.0001) but not in the group with ankle valgus (p = 0.9161). FAO values of ≥12.14% were a strong predictor (79.2%) of ankle valgus deformity. Subluxation of the middle facet was not as severe and did not influence the overall alignment in patients with PCFD who had valgus of the ankle (Class E). These findings suggest a distal peritalar reduction in the presence of a proximal deformity, making MFS an imprecise disease parameter in this scenario. An FAO value of ≥12.14% was a strong indicator of ankle deformity in patients with PCFD. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.