Multiple factors contributing to the metatarsal head eversion in hallux valgus deformity. A prospective study using weight-bearing CT.

PURPOSE: Recently first tarsometatarsal arthrodesis for hallux abducto valgus (HAV) has been advocated as the sole procedure to correct the multiplanar components of the deformity. However, recent debate suggests other factors such as rearfoot pronation and metatarsal torsion affect frontal plane metatarsal eversion and sesamoid positioning. Using weight-bearing CT, 12 feet (12 subjects) with HAV deformities were placed in positions of maximum rearfoot pronation and supination in order to study the effects on metatarsal eversion, sesamoid rotation/displacement, and secondarily the influence of first metatarsal torsion. Sesamoid displacement was quantified by the novel use of the sesamoid displacement angle. PRINCIPLE RESULTS: Although first metatarsal eversion was nearly double in the pronated versus supinated foot, the difference was not statistically significant. Therefore, the bulk of first metatarsal eversion was not secondary to rearfoot eversion. Conversely, a significant positive correlation was found between metatarsal torsion and metatarsal head eversion angles in both supinated and pronated foot positions, with the strongest correlation with rearfoot pronation. Finally, significant increases in sesamoid displacement angles were noted with pronation. MAJOR CONCLUSIONS: The findings of the present study support the contention that multiple factors are associated with frontal plane first metatarsal eversion and sesamoid displacement. Weight-bearing CT scanning can be used to effectively evaluate the frontal plane components in HAV deformities. The sesamoid displacement angle appears to be a useful adjunct to evaluating the hallucal sesamoids. For surgical correction of the deformity, consideration should be given to pre-operative weight-bearing CT evaluation of the foot. This can illuminate the effects of rearfoot/medial column pronation and the potential influence of metatarsal torsion on the frontal plane components of this triplane deformity. In this way the potential for post-operative HAV recurrence can be minimized.

The distal metatarsal articular angle in hallux valgus deformities. Comparisons of radiographic and weightbearing CT scan measurements with variations in hindfoot position.

BACKGROUND: When evaluating hallux valgus (HV) deformity with anteroposterior (AP) foot radiographs, the distal metatarsal articular angle (DMAA) has been the subject of frequent debate. Although a straightforward indicator of structural alignment of the distal first metatarsal articular surface, inter- and intraobserver measurements can vary widely. Alterations in the radiographic appearance of bony "structure" with positional changes of the foot/foot bones in HV deformities in no small part contributes to these inaccuracies. The aim of this study was to determine the effect of hindfoot position on the DMAA. METHODS: Four different radiologic images were obtained for 15 subjects with HV: three AP foot radiographs (standard weightbearing, foot supinated, foot pronated) and one weightbearing CT (WBCT) scan. For each image, five investigators measured the DMAA in order to assess reliability. RESULTS: Mean DMAA values measured from the images indicated that the angle was highest with the pronated foot (15.3 (95% CI, 10.3-20.3) degrees) and lowest when measured from the CT image (11.6 (95% CI, 7.3-16.0) degrees). For all image types, the intraclass correlation coefficient was greater than 0.9 and statistically significant (P < 0.0005). CONCLUSION: Hindfoot positions affected radiographic DMAA/mean DMAA values, with values highest with feet in pronated attitudes. Unlike radiographic projections, the WBCT appears less likely to overestimate DMAA and is not subject to variations in foot positioning. In the preoperative evaluation of HV deformities, this points to the potential use of WBCT as a reference standard. For markedly severe HV deformities that may present with AP radiographs with marked first metatarsal head "roundness," the use of WBCT is the intuitive choice. The results indicate excellent reliability in measurements of DMAA between all five investigators. As such, the measurement method used to determine DMAA in this study was dependable and reproducible. LEVEL OF EVIDENCE: Level II.

The C-sign in normal feet: a prospective study and novel imaging algorithm for subtalar joint tarsal coalition.

OBJECTIVE: The C-sign on lateral radiographs has been subject to considerable debate with respect to its reliable association to subtalar joint tarsal coalition. The purpose of this study was to determine to what degree subtalar joint pronation factors into (a) the appearance of both complete and incomplete type A C-signs and (b) the conspicuity of the middle facet in both flatfeet and rectus feet. STUDY DESIGN: Forty-seven normal adult volunteers were enrolled into the study with a total of 92 feet, of which 42 were flexible flatfeet and 50 were rectus feet with normal subtalar joint range of motion. Lateral weight-bearing radiographs were taken of each foot in a position of (a) standing and (b) maximum subtalar joint pronation. Investigators evaluated images for the visibility of the middle facet, and the presence or absence of a continuous or interrupted type A C-sign. PRINCIPAL RESULTS: No continuous C-signs were produced with extreme pronation in either the rectus/normal or flatfoot populations. Three incomplete type A C-signs were produced with pronation, two of which were in rectus feet. Two absent middle facet signs were also produced with pronation. Absent visualization of the facet had high positive and negative predictive values (1.00 and 0.99 respectively) for the presence of an incomplete C-Sign. MAJOR CONCLUSIONS: The standard, routine lateral foot/ankle radiographic image protocol for suspected talocalcaneal coalition should be modified routinely positioning the foot maximally supinated, thereby minimizing the possibility of producing C-signs (complete or type A incomplete) and/or absent middle facet signs with pronation in either normal or flatfeet. A novel algorithmic approach can then be simply applied to determine when ancillary CT scanning is warranted for suspected posterior facet coalition.

A Novel Thermochromic Liquid Crystal Fabric Design for the Early Detection of High-Risk Foot Complications

Background: We developed a prototype of a novel thermochromic liquid crystal (TLC)­coated fabric with an extended temperature range and enhanced sensitivity. By incorporating color and pattern recognition into the fabric, rapid determination of the underlying pedal temperature is facilitated. The purpose of this study was to evaluate the accuracy of the TLC fabric as a potential diagnostic aid for identifying complications in the high-risk foot. Methods: The hands of 100 individuals were used to compare the mean maximum temperatures indicated by the fabric versus standard thermal camera images. Findings were statistically analyzed using a paired t test, with significance defined as P < .05. Results: Except for the tip of the thumb and regions in the palm, there were no statistically significant differences between mean maximum temperatures measured with the thermal camera and those detected with the TLC fabric. Minor differences were relatively consistent in all nine regions of the hand and were not considered to be clinically significant. Conclusions: Using direct visual analysis, we demonstrated that a novel TLC fabric could accurately map temperatures in the palmar surface of the hand. The findings support the continued development of a temperature-sensitive sock that can be used in the home to monitor for temperature changes that may indicate the onset of complications in the high-risk foot.

Appearance of osteolysis with melorheostosis: redefining the disease or a new disorder? A novel case report with multimodality imaging.

We present a case report of melorheostosis with the novel radiographic finding of underlying cortical resorption. A number of radiographic patterns of melorheostosis have been described; however, the combination of new bone formation and resorption of the original cortex appears unique. Although the presence of underlying lysis has been postulated in published studies, direct radiographic evidence of bony resorption in melorheostosis has not been reported. These findings can be subtle and might go unnoticed using standard imaging. An in-depth review of the radiographic features is presented, including multimodality imaging with magnetic resonance imaging and computed tomography.

Incidental findings of massive heel spurs in a veteran with a variant of psoriatic arthritis.

A middle-aged man presented for left foot diabetic ulcer care. Pedal radiographs were negative for signs of osteomyelitis. However, asymptomatic incidental osseous findings demonstrated significant plantar and posterior calcaneal spurring possibly consistent with diffuse idiopathic skeletal hyperostosis (DISH). A differential of DISH, psoriatic arthritis, Reiter's, and ankylosing spondylitis was developed. Subsequent spinal imaging and laboratory work-up did not satisfy the diagnostic criteria for DISH. This case illustrates radiographic changes characteristic of multiple seronegative arthropathies. On initial presentation a diagnosis of DISH was most likely, but with further imaging studies a diagnosis of a variant of psoriatic arthritis may be more correct.

Extended pedal imaging via modifications of the traditional forefoot axial radiographic study: teaching new tricks to an old dog? an initial report with case presentations.

BACKGROUND: The plain film forefoot axial radiographic view is a specialized view in podiatric imaging. In everyday office practice, an axial orthoposer is used, and the study is nonweightbearing. Largely useless for imaging functional pathology, the forefoot axial view's main use centers around imaging of the plantar metatarsal heads and the hallucal sesamoid complex. To this end, the name "forefoot" is somewhat of a misnomer, and the view is also known as the sesamoid axial study. METHODS: We report on the initial use of oblique sesamoid or "skyline" axial studies for juxtacortical lesions of the sesamoid bones and more proximal dorsolateral tarsal structures, an area traditionally difficult to assess accurately with plain film imaging. RESULTS: Rather simple, empiric modifications in the forefoot axial technique allowed for 1) "skyline" imaging of exostotic surface lesions involving the dorsal, medial, and lateral midfoot bones, and 2) significant improvement in imaging hallucal sesamoid pathology. CONCLUSIONS: Although the proposed oblique forefoot axial modifications empirically add two additional plain film radiographic studies to a standard forefoot axial study, our initial study suggests that the imaging benefits far outweigh the liabilities. This is especially true when one considers the difficulties encountered when employing standard plain film pedal in an effort to clarify or delineate pathologic processes involving the midfoot bones or metatarsal bases. It is hoped that this study will spawn further use and research of these "novel" views.