Influence of Tibial Component Design Features and Interference Fit on Implant-Bone Micromotion in Total Ankle Replacement: A Finite Element Study.

BACKGROUND: Implant survivorship in uncemented total ankle replacement (TAR) is dependent on achieving initial stability. This is because early micromotion between the implant and bone can disrupt the process of osseointegration, leading to poor long-term outcomes. Tibial implant fixation features are designed to resist micromotion, aided by bony sidewall retention and interference fit. The goal of this study was to investigate design-specific factors influencing implant-bone micromotion in TAR tibial components with interference fit. METHODS: Three implant designs with fixation features representative of current TAR tibial components (ARC, SPIKES, KEEL) were virtually inserted into models of the distal tibias of 2 patients with end-stage ankle arthritis. Tibia models were generated from deidentified patient computed tomography scans, with material properties for modeling bone behavior and compaction during press-fit. Finite element analysis (FEA) was used to simulate 2 fixation configurations: (1) no sidewalls or interference fit, and (2) sidewalls with interference fit. Load profiles representing the stance phase of gait were applied to the models, and implant-bone micromotions were computed from FEA output. RESULTS: Sidewalls and interference fit substantially influenced implant-bone micromotions across all designs studied. When sidewalls and interference fit were modeled, average micromotions were less than 11 µm, consistent across the stance phase of gait. Without sidewalls or interference fit, micromotions were largest near either heel strike or toe-off. In the absence of sidewalls and interference fit, the amount of micromotion generally aligned inversely with the size of implant fixation features; the ARC design had the largest micromotion (~540 µm average), whereas the KEEL design had the smallest micromotion (~15 µm). CONCLUSION: This study presents new insights into the effect of TAR fixation features on implant-bone micromotion. With sidewalls and interference fit, micromotion is predicted to be minimal for implants, whereas with no sidewalls and no interference fit, micromotion depended primarily on the implant design. CLINICAL RELEVANCE: This study presents new insights into the effect of TAR primary fixation features on implant-bone micromotion. Although design features heavily influenced implant stability in the model, their influence was greatly diminished when interference fit was introduced. The results of this study show the relative importance of design features and interference fit in the predicted initial stability of uncemented TAR, potentially a key factor in implant survivorship.

Trends in the Use of Weightbearing Computed Tomography.

Background: This review aimed to critically appraise the most recent orthopedic literature around cone beam weightbearing computed tomography (WBCT), summarizing what evidence has been provided so far and identifying the main research trends in the area. Methods: This scoping review was performed on studies published between January 2013 and December 2023 on the Pubmed database. All studies (both clinical and nonclinical) in which WBCT had been used were critically analyzed to extract the aim (or aims) of the study, and the main findings related to the role of this imaging modality in the diagnostic pathway. Results: Out of 1759 studies, 129 were selected. One hundred five manuscripts (81%) dealt with elective orthopedic conditions. The majority of the analyses (88 studies; 84%) were performed on foot and ankle conditions, while 13 (12%) studies looked at knee pathologies. There was a progressive increase in the number of studies published over the years. Progressive Collapsing Foot Deformity (22 studies; 25%) and Hallux Valgus (19 studies; 21%) were frequent subjects. Twenty-four (19%) manuscripts dealt with traumatic conditions. A particular interest in syndesmotic injuries was documented (12 studies; 60%). Conclusions: In this review, we documented an increasing interest in clinical applications of weightbearing CT in the orthopedic field between 2013 and 2023. The majority of the analyses focused on conditions related to the foot and the ankle; however, we found several works investigating the value of WBCT on other joints (in particular, the knee).

Cone-Beam Weight-Bearing Computed Tomography of Ankle Arthritis and Total Ankle Arthroplasty.

Weight-bearing computed tomography has multiple advantages in evaluating the hindfoot and ankle. It can assess hindfoot and ankle alignment, pathology in ankle arthritis, and complications related to total ankle replacements. It is an essential tool in ankle osteoarthritis diagnostic, preoperative planning, and total ankle replacement outcomes. It allows for better accuracy and reproducibility of alignment and implant size. In addition, it has the potential to more assertively detect complications related to weight bearing.

Magnetic Resonance Imaging of Total Ankle Arthroplasty: State-of-The-Art Assessment of Implant-Related Pain and Dysfunction.

Total ankle arthroplasty (TAA) is an effective alternative for treating patients with end-stage ankle degeneration, improving mobility, and providing pain relief. Implant survivorship is constantly improving; however, complications occur. Many causes of pain and dysfunction after total ankle arthroplasty can be diagnosed accurately with clinical examination, laboratory, radiography, and computer tomography. However, when there are no or inconclusive imaging findings, magnetic resonance imaging (MRI) is highly accurate in identifying and characterizing bone resorption, osteolysis, infection, osseous stress reactions, nondisplaced fractures, polyethylene damage, nerve injuries and neuropathies, as well as tendon and ligament tears. Multiple vendors offer effective, clinically available MRI techniques for metal artifact reduction MRI of total ankle arthroplasty. This article reviews the MRI appearances of common TAA implant systems, clinically available techniques and protocols for metal artifact reduction MRI of TAA implants, and the MRI appearances of a broad spectrum of TAA-related complications.

Multiaxial 3D MRI of the Ankle: Advanced High-Resolution Visualization of Ligaments, Tendons, and Articular Cartilage.

MRI is a valuable tool for diagnosing a broad spectrum of acute and chronic ankle disorders, including ligament tears, tendinopathy, and osteochondral lesions. Traditional two-dimensional (2D) MRI provides a high image signal and contrast of anatomic structures for accurately characterizing articular cartilage, bone marrow, synovium, ligaments, tendons, and nerves. However, 2D MRI limitations are thick slices and fixed slice orientations. In clinical practice, 2D MRI is limited to 2 to 3 mm slice thickness, which can cause blurred contours of oblique structures due to volume averaging effects within the image slice. In addition, image plane orientations are fixated and cannot be changed after the scan, resulting in 2D MRI lacking multiplanar and multiaxial reformation abilities for individualized image plane orientations along oblique and curved anatomic structures, such as ankle ligaments and tendons. In contrast, three-dimensional (3D) MRI is a newer, clinically available MRI technique capable of acquiring high-resolution ankle MRI data sets with isotropic voxel size. The inherently high spatial resolution of 3D MRI permits up to five times thinner (0.5 mm) image slices. In addition, 3D MRI can be acquired image voxel with the same edge length in all three space dimensions (isotropism), permitting unrestricted multiplanar and multiaxial image reformation and postprocessing after the MRI scan. Clinical 3D MRI of the ankle with 0.5 to 0.7 mm isotropic voxel size resolves the smallest anatomic ankle structures and abnormalities of ligament and tendon fibers, osteochondral lesions, and nerves. After acquiring the images, operators can align image planes individually along any anatomic structure of interest, such as ligaments and tendons segments. In addition, curved multiplanar image reformations can unfold the entire course of multiaxially curved structures, such as perimalleolar tendons, into one image plane. We recommend adding 3D MRI pulse sequences to traditional 2D MRI protocols to visualize small and curved ankle structures to better advantage. This article provides an overview of the clinical application of 3D MRI of the ankle, compares diagnostic performances of 2D and 3D MRI for diagnosing ankle abnormalities, and illustrates clinical 3D ankle MRI applications.

Ankle osteoarthritis: Toward new understanding and opportunities for prevention and intervention.

The ankle infrequently develops primary osteoarthritis (OA), especially when compared to the hip and the knee. Ankle OA instead generally develops only after trauma. The consequences of end-stage ankle OA can nonetheless be extremely debilitating, with impairment comparable to that of end-stage kidney disease or congestive heart failure. Disconcertingly, evidence suggests that ankle OA can develop more often than is generally appreciated after even low-energy rotational ankle fractures and chronic instability associated with recurrent ankle sprains, albeit at a slower rate than after more severe trauma. The mechanisms whereby ankle OA develops after trauma are poorly understood, but mechanical factors are implicated. A better understanding of the prevalence and mechanical etiology of post-traumatic ankle OA can lead to better prevention and mitigation. New surgical and conservative interventions, including improved ligamentous repair strategies and custom carbon fiber bracing, hold promise for advancing treatment that may prevent residual ankle instability and the development of ankle OA. Studies are needed to fill in key knowledge gaps here related to etiology so that the interventions can target key factors. New technologies, including weight bearing CT and biplane fluoroscopy, offer fresh opportunities to better understand the relationships between trauma, ankle alignment, residual ankle instability, OA development, and foot/ankle function. This paper begins by reviewing the epidemiology of post-traumatic ankle OA, presents evidence suggesting that new treatment options might be successful at preventing ankle OA, and then highlights recent technical advances in understanding of the origins of ankle OA to identify directions for future research.

Utilization of telemedicine for diagnosis and follow-up within foot and ankle orthopaedic surgery: A narrative review of the literature.

BACKGROUND: Telemedicine has seen increasing adoption in healthcare over the past two decades, with proven clinical efficacy in several medical specialties. Orthopedics surgery has shown potential benefits from telemedicine implementation. OBJECTIVE: This review aims to evaluate the impact of telemedicine on clinical outcomes and patient and physician preferences in foot and ankle orthopedics, providing insight into the potential role of telemedicine within this subspecialty. METHODS: Multiple databases were searched for relevant articles on telemedicine in foot and ankle orthopedics. Inclusion criteria encompassed articles on telemedicine use and foot and ankle orthopedic care. Data included patient demographics, reasons for visits, duration of telemedicine, and outcomes. Analysis involved descriptive statistics, and a narrative approach to describe outcomes. RESULTS: Out of 218 articles, 12 met the inclusion criteria, comprising a total of 1,535 patients. Telemedicine visits were used for follow-up care, opinion consultations, monitoring, postoperative care, and treatment of various orthopedic conditions. Clinical outcomes demonstrated equivalence to in-person care. Patients expressed satisfaction with telemedicine but preferred in-person visits for future appointments. Physicians held neutral attitudes towards telemedicine, with concerns about the lack of physical examination. CONCLUSION: This review highlights the benefits of telemedicine in foot and ankle orthopedics. Telemedicine provides an alternative to in-person visits, improving patient access to care and offering cost and time savings. However, patient and physician preferences for in-person visits suggest a need to address concerns related to physical examination limitations. Telemedicine can supplement traditional care, but further research is required to explore its applicability in new patient consultations and optimize physician engagement.

Hindfoot Alignment in Flexible Cavovarus Deformity Under Orthostatic and Coleman Block Test Positions: A Weightbearing Computed Tomography Study.

BACKGROUND: Flexible cavovarus deformity is prevalent and the Coleman block test is frequently used to assess the first ray plantarflexion malpositioning in the overall deformity as well as the flexibility of the hindfoot. The objective was to assess and compare the weightbearing computed tomography (WBCT) 3-dimensional (3D) changes in clinical and bone alignment in flexible cavovarus deformity patients when performing the Coleman block test when compared to normal standing position and to controls. METHODS: Twenty patients (40 feet) with flexible cavovarus deformity and 20 volunteer controls (40 feet) with normal foot alignment underwent WBCT imaging of the foot and ankle. Cavovarus patients were assessed in normal orthostatic and Coleman block test positions. Foot and ankle offset (FAO), hindfoot alignment angle (HAA), talocalcaneal angle (TCA), subtalar vertical angle (SVA) and talonavicular coverage angle (TNCA) and a CT-simulated soft tissue envelope image, WBCT clinical hindfoot alignment angle (WBCT-CHAA), were evaluated by 2 readers. Measurements were compared between cavovarus nonstressed and stressed positions and to controls. P values of .05 or less were considered significant. RESULTS: The intra- and interobserver intraclass correlation coefficient were good or excellent for all WBCT measurements. Cavovarus patients demonstrated significant correction of WBCT-CHAA (9.7 ± 0.4 degrees), FAO (2.6 ± 0.4%), and TNCA (8.8 ± 1.8 degrees) when performing the Coleman block test (all P values <.0001). However, WBCT-CHAA and FAO measurements were still residually deformed and significantly different from controls (P values of .001 and <.0001, respectively). TNCA values corrected to values similar to healthy controls (P = .29). No differences were observed in cavovarus patients during Coleman block test for the coronal measures: HAA, TCA, and SVA measurements. CONCLUSION: In this study, we observed improvement in the overall 3D WBCT alignment (FAO), axial plane adduction deformity (TNCA), as well as CT simulated clinical hindfoot alignment (WBCT-CHAA) in flexible cavovarus deformity patients when performing a Coleman block test. However, we did not find improvement in measures of coronal alignment of the hindfoot, indicating continued varus positioning of the hindfoot in these patients.

Quantification of First Metatarsal Joint Surface Interactions in Hallux Rigidus Using Distance and Coverage Mapping: A Case-Control Study.

BACKGROUND: Weightbearing cone-beam computed tomography (WBCT) has proven useful for analysis of structural changes of the foot and ankle when compared to conventional radiographs. WBCT allows for extraction of distance and coverage mapping metrics, which may provide novel insight into hallux rigidus (HR). This study retrospectively assessed HR joint space using distance and coverage mapping in a case-control study. METHODS: WBCT images of the foot and ankle for 20 symptomatic HR and 20 control patients were obtained. Three-dimensional models were created and analyzed using a custom semiautomatic measurement algorithm. Distance and coverage mapping metrics for the first metatarsophalangeal and metatarsosesamoid joints were extracted from the models and compared between cohorts. Relationships between these metrics and visual analog scale (VAS) scores, a patient-reported outcome of pain, were assessed in HR patients. RESULTS: Overall first metatarsophalangeal joint space narrowing was noted in HR patients when compared to controls by an average of 11.8% (P = .02). However, no significant changes in the overall coverage of the joint were noted. Decreased joint space width and increased surface-to-surface coverage were only and particularly observed at the plantar medial quadrant of the first metatarsal head in HR patients relative to controls. VAS score was significantly but weakly correlated with dorsolateral quadrant coverage (R2 = 0.26, P = .03). CONCLUSION: Distance and coverage mapping serve as a complementary option to current techniques of quantifying HR changes. These metrics can expand the scope of future work investigating joint articulation changes in HR.

Correction of progressive collapsing foot deformity classes after isolated arthroscopic subtalar arthrodesis.

INTRODUCTION: Subtalar osteoarthritis in the context of flatfoot (recently renamed Progressive Collapsing Foot Deformity (PCFD)) may be treated through subtalar joint (SJ) arthrodesis with anticipated consequences on three-dimensional bony configuration. This study investigates the correction of PCFD-related deformities achieved after Anterolateral Arthroscopic Subtalar Arthrodesis (ALAPSTA). METHODS: In this retrospective study, we evaluated pre- and post-operative (at 6 months) weight bearing computed tomography (WBCT) images of patients diagnosed with PCFD with a degenerated SJ (2 A according to PCFD classification) and/or peritalar subluxation (2D) with or without associated flexible midfoot and/or forefoot deformities (1B, 1 C and 1E) which underwent ALAPSTA as a standalone procedure between 2017 and 2020. Multiple measurements were used to assess and compare pre and post-operative PCFD classes. RESULTS: Thirtythree PCFD (33 patients, median age 62) were included in the study. Preoperative medial facet subluxation was 28.3 % (IQR, 15.1 to 49.3 %). Overall PCFD 3D deformity improved with a reduction of the foot and ankle offset from 9.3 points (IQR, 7.8 to 12) to 4 (IQR, 0.9 to 7) (p < 0.001). Class A-hindfoot valgus (median tibiocalcaneal angle and median calcaneal moment arm improved by 9.4 degrees (p < 0.001) and 11 mm (p < 0.001), respectively), class B-midfoot abduction (median talonavicular coverage angle improved by 20.5 degrees, p < 0.001) and class C-forefoot varus (median sagittal talo-first metatarsal angle improved by 10.2 degrees (p < 0.001)) were significantly corrected after surgery. Class D was difficult to assess due to the fusion procedure. No patient had a pre-operative valgus deformity at the ankle (no class E), and no significant change of the talar tilt was observed (p = 0.12). CONCLUSION: In this series, ALAPSTA performed as a standalone procedure to treat patients diagnosed with PCFD with a degenerated subtalar joint and/or peritalar subluxation was effective not only at correcting hindfoot alignment but also flexible midfoot abduction and flexible forefoot varus. LEVEL OF EVIDENCE: Level IV, case series.

Spontaneous Reduction in the Intermetatarsal Angle in Distal First Metatarsal Osteotomies with No Lateral Head Displacement in Hallux Valgus.

BACKGROUND: The outcomes of first metatarsal (M1) distal osteotomies in hallux valgus (HV) can be improved, especially for intermetatarsal angle (IMA) correction, which is mainly based on lateral displacement of the M1 head (i.e., translation) through the osteotomy. Conversely, there is a spontaneous reduction in the IMA in first metatarsophalangeal joint (MTP1) arthrodesis. But we do not know whether this can be applied to distal osteotomies. We propose a distal osteotomy, called 3D chevron, which combines supination and varization of the M1 head. This might realign soft tissues around the MTP1, potentially leading to a spontaneous reduction in the IMA by an analogous mechanism to MTP1 fusion. Therefore, our study aimed to assess whether spontaneous reductions in IMAs exist in distal M1 osteotomies in the absence of lateral translations of M1 heads. METHODS: A prospective continuous series of 25 3D chevrons was performed. Two groups were formed during surgery. Patients requiring no M1 head lateral displacement were included in the "successful correction without translation" group, and patients requiring M1 head lateral displacement were included in the "failed correction without translation" group. Radiographic analysis was performed preoperatively and at 1 year postoperatively. RESULTS: Twenty-two women and three men, with a mean age of 44.8 ± 14.2 years and a mean body mass index of 22.6 ± 4.1 kg/m2, underwent follow-up at one year after surgery. The "successful correction without translation" group was composed of HV with milder deformities (13/25 HVs, median preoperative IMA = 13 (IQR 2)) compared to the "failed correction without translation" group (median IMA = 16 (IQR 2.25) p < 0.001). Spontaneous reductions in IMAs were observed in the "successful correction without translation" group, with a median decrease in the IMA of 6 degrees (CI95%[5.5; 8.0]; p < 0.001) between preoperative and 1-year radiographs. CONCLUSION: Distal osteotomies allow for spontaneous reduction in the IMA in HV. First metatarsal head translation through an osteotomy should not be considered as the only procedure to correct IMAs in distal osteotomies.

The role of computed tomography with external rotation and dorsiflexion in decision making for acute isolated non-displaced posterior malleolar fractures Bartonícek and Rammelt type II: a prospective study.

PURPOSE: Our objective was to evaluate the syndesmotic and fracture instability using conventional ankle computed tomography (CT) with stress maneuvers. METHODS: A consecutive sample of 123 individuals with an ankle sprain was assessed for eligibility. In total, 33 patients met the inclusion criteria. All patients underwent a magnetic resonance imaging (MRI) and CT scan with stress maneuvers (CTSM). The patterns of ligament tears f were classified using West Point grades I, IIA, IIB, III. Mann-Whitney test was used to test the differences in the numerical variables between injured and uninjured syndesmoses. The Spearman correlation tested the strength of the association between the tibial joint surface involved in posterior malleolus fracture and syndesmotic instability. RESULTS: In MRI, two patterns of syndesmotic ligament injury predominated. A completely torn anterior inferior tibiofibular (AITFL) and interosseous tibiofibular ligaments (ITFL) and a completely torn AITFL were combined with a partially torn ITFL. In the neutral phase CTSM and during the stress phase the median difference of the narrowest tibiofibular distance between injured and uninjured syndesmoses was 0.2 mm (P = 0.057) and 2.3 mm (P < 0.0001), respectively. There was no association between the percentage of involvement of the posterior tibial joint surface in the posterior malleolar fracture and syndesmotic instability as measured with CTSM. CONCLUSION: The conventional computed tomography with external rotation and dorsiflexion represents a reproducible and accurate diagnostic option for detecting syndesmosis instability and fracture instability in acute isolated non-displaced posterior malleolar fractures Bartonícek and Rammelt type II. LEVEL OF EVIDENCE: Prospective study among consecutive patients (Diagnosis); Level of evidence, 2.

Influence of sidewall retention and interference fit in total ankle replacement on implant-bone micromotion: A finite element study.

The success of uncemented total ankle replacement (TAR) is linked to initial stability because bony ingrowth depends upon limited early micromotion. Tibial implant design fixation features resist micromotion aided by bony sidewall retention and interference fit. Our goal was to investigate factors influencing implant-bone micromotion in TAR. Two TAR tibial components were virtually inserted into CT-derived computer models of two distal tibias from patients with end-stage ankle arthritis. Density-based inhomogeneous material assignment was used to model bone compaction during press-fit. Finite element analysis (FEA) was used to simulate three fixation cases: (1) no sidewalls + line-to-line fit, (2) sidewalls + line-to-line fit, and (3) sidewalls + 50, 100, or 200 µm interference fit. Kinetic profiles from the stance phase of gait were simulated and micromotions computed from FEA output. Without sidewalls or interference fit, micromotions were largest in early and late stance, with largest micromotions (averaging ~150-250 µm) observed near heel strike. Micromotions decreased 39%-62% when sidewalls were retained. When interference fit was also modeled, micromotions decreased another 37%-61% to ~10 µm. Micromotion differences between patients persisted with sidewall retention but largely disappeared with interference fit. This study presents new insights into the effects of TAR fixation features on implant-bone micromotion. Stability appeared to be influenced by surrounding bone quality, but this influence was greatly diminished when interference fit was introduced. More complete understanding of TAR implant features and performance is needed, but our results show the importance of bone quality and interference fit in the stability of uncemented TAR.

Socioeconomic Status and Race Are Rarely Reported in Randomized Controlled Trials for Achilles Tendon Pathology in the Top 10 Orthopaedic Journals: A Systematic Review.

Background: Randomized controlled trials (RCTs) are crucial in comparative research, and a careful approach to randomization methodology helps minimize bias. However, confounding variables like socioeconomic status (SES) and race are often underreported in orthopaedic RCTs, potentially affecting the generalizability of results. This study aimed to analyze the reporting trends of SES and race in RCTs pertaining to Achilles tendon pathology, considering 4 decades of data from top-tier orthopaedic journals. Methods: This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and used PubMed to search 10 high-impact factor orthopaedic journals for RCTs related to the management of Achilles tendon pathology. The search encompassed all articles from the inception of each journal until July 11, 2023. Data extraction included year of publication, study type, reporting of SES and race, primary study location, and intervention details. Results: Of the 88 RCTs identified, 68 met the inclusion criteria. Based on decade of publication, 6 articles (8.8%) reported on SES, whereas only 2 articles (2.9%) reported on race. No RCTs reported SES in the pre-1999 period, but the frequency of reporting increased in subsequent decades. Meanwhile, all RCTs reporting race were published in the current decade (2020-2030), with a frequency of 20%. When considering the study location, RCTs conducted outside the United States were more likely to report SES compared with those within the USA. Conclusion: This review revealed a concerning underreporting of SES and race in Achilles tendon pathology RCTs. The reporting percentage remains low for both SES and race, indicating a need for comprehensive reporting practices in orthopaedic research. Understanding the impact of SES and race on treatment outcomes is critical for informed clinical decision making and ensuring equitable patient care. Future studies should prioritize the inclusion of these variables to enhance the generalizability and validity of RCT results.

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.

Normal Values for Distal Tibiofibular Syndesmotic Space With and Without Subject-Driven External Rotation Stress.

BACKGROUND: The diagnosis and treatment of distal tibiofibular syndesmosis (DTFS) injury can be challenging, especially in cases of subtle instability that may be masked on 2-dimensional conventional radiographs. Weightbearing computed tomography (WBCT) has recently emerged as a useful diagnostic tool allowing direct assessment of distal tibiofibular area widening. The purpose of the current study was to examine and report normal threshold values for DTFS area measurements in a cohort of healthy volunteers, assessing the ankles in natural weightbearing position and under subject-driven external rotation stress. METHODS: In this prospective study, we enrolled 25 healthy volunteers without a history of DTFS injury or high ankle sprain, previous foot and ankle surgery, or current ankle pain. Subjects with any prior ankle injuries were excluded. Study participants underwent bilateral standing nonstress and external rotation stress WBCT scans. The DTFS area (mm2) was semiautomatically quantified on axial-plane WBCT images 1 cm proximal to the apex of the talar dome using validated software. Syndesmosis area values were compared between "unstressed" and "stressed" ankles, as well as left and right ankles. Statistical analysis was performed using independent t tests/Wilcoxon analysis with statistical significance defined as P <.05. RESULTS: The study cohort consisted of 50 ankles in 25 patients (12 males, 48%) with a mean age of 28.7 ± 9.3 years. In the unstressed ankle, the mean pooled DTFS area was determined to be 103.8 + 20.8 mm2. The mean syndesmosis area of unstressed left ankles (104.2 + 19.5 mm2) was similar to unstressed right ankles (109.2 + 17.2 mm2) in the cohort (P = .117). With external rotation stress, the DTFS area of left ankles (mean difference -0.304 mm2, CI -12.1 to 11.5; P = .082), right ankles (mean difference -5.5 mm2, CI 16.7-5.7; P = .132), and all ankles (mean difference -2.9 mm2, CI -10.8 to 5.1; P = .324) remained similar. CONCLUSION: This study presents normal values and range for DTFS area calculation. In uninjured ankles with expected intact ligaments, subject-driven external rotation stress did not result in significant widening of the DTFS space as imaged on with WBCT. LEVEL OF EVIDENCE: Level II, cross-sectional study.

Weightbearing Computed Tomography vs Conventional Tomography for Examination of Varying Degrees of Lisfranc Injures: A Systematic Review of the Literature.

Background: Lisfranc injuries, if not accurately diagnosed, can result in chronic pain and instability. Previous studies have examined ultrasonographs, radiographs, magnetic resonance imaging (MRI), and conventional computed tomography (CT) scan to differentiate Lisfranc instability, but they focused on a healthy/injured scale without differentiating subtle injury. Weightbearing CT (WBCT) has emerged as a diagnostic tool for detecting subtle Lisfranc injuries. This systematic review aimed to compare WBCT with conventional CT in diagnosing Lisfranc injury, and the ability to differentiate injuries of varying severities. Methods: The review encompassed PubMed, CINAHL, MEDLINE, SPORTDiscus, and Web of Science databases from inception until July 5, 2023. Inclusion criteria involved studies on CT and/or WBCT for Lisfranc injuries and nonoperative studies. Exclusion criteria composed case reports, commentaries, postoperative imaging studies, pediatric patients, studies with nonobjective radiographic measurements, studies exclusively focused on injury classification, and studies with fewer than 5 patients because of poor statistical power. Data extraction focused on radiographic measurements of the Lisfranc complex, categorized into conventional CT, partial WBCT, and total WBCT. Results: Out of the initially retrieved 489 articles, 9 met the inclusion criteria. Several studies consistently demonstrate that WBCT provides a higher level of accuracy in measuring the Lisfranc area, offering enhanced sensitivity to detect subtle alterations in joint structure. Moreover, WBCT exhibits superior sensitivity in distinguishing between healthy Lisfranc joints and those with injuries, particularly when identifying dorsal ligament damage. This imaging modality allows for the detection of significant variations in critical measurements like first-second metatarsal (M1-M2) distance, first cuneiform (C1)-M2 distance, and joint volumes, enabling a more comprehensive assessment of Lisfranc joint health especially with subtle instability. Conclusion: This review evaluates the extant literature on WBCT's utility in diagnosing Lisfranc injuries and compares its effectiveness to CT in distinguishing between injuries of varying severity. WBCT, with reliable measurement techniques, appears more adept at detecting subtle Lisfranc instability compared to CT, likely by allowing the assessment of injury under load.

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

Background: 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. Methods: 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. Results: 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. Conclusions: 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. Level of Evidence: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Relationship Between Obesity and Medial Longitudinal Arch Bowing.

BACKGROUND: 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). METHODS: 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. RESULTS: 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. CONCLUSION: 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 OF EVIDENCE: Level III, retrospective cohort study.