Triplanar Quantitative Radiographic Analysis of the First Metatarsal-Phalangeal Joint in the Hallux Abductovalgus Deformity

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.

Hallucal sesamoiditis on a bipartite sesamoid bone: An uncommon cause of chronic great toe pain

The pathologies and lesions affecting the sesamoid bones of the hallux are uncommon and can be easily overlooked. Among them, sesamoiditis is a relatively rare condition known to cause severe great toe pain; lack of awareness of this particular entity leads to misdiagnosis, delayed treatment, and contributes to significant morbidity. Herein, we present a chronic sesamoiditis case occurring on a medial bipartite sesamoid bone, presenting as chronic great toe pain. The main purpose of this work is to discuss the role of magnetic resonance imaging and X-rays in the diagnosis process. To the best of our knowledge, no cases of great toe sesamoiditis occurring on a bipartite bone in no-athletic patients have yet been reported.

Multiplanar, Multivariate Analyses of Hallux Valgus Radiographic Parameters

Hallux valgus is a complex condition understood to involve pathomechanics in all 3 of the cardinal planes. Despite this, the bulk of its historical evaluation has been in the transverse plane, and one might argue that the traditional and more commonly performed univariate and bivariate analyses within the literature do not comprehensively describe the potential interrelationships between the planes during perioperative assessment. Therefore this investigation aimed to evaluate relationships between common radiographic parameters measured in the three cardinal planes by means of a multivariate regression analysis. Serial analyses utilizing the first intermetatarsal angle, hallux valgus angle, tibial sesamoid position, proximal articular set angle, Engel's angle, first metatarsal inclination angle, and the sesamoid rotation angle were performed with varying dependent and independent variables. The tibial sesamoid position (p < .001) and proximal articular set angle (p = .014) were found to be independently associated with the first intermetatarsal angle, while the hallux valgus angle (p = .712), Engel's angle (p = .646), first metatarsal inclination angle (p = .097), and sesamoid rotation angle (p = .099) were not. The tibial sesamoid position (p = .003), proximal articular set angle (p < .001), Engel's angle (p = .006), and sesamoid rotation angle (p = .003) were found to be independently associated with the hallux valgus angle, while the first intermetatarsal angle (p = .712) and first metatarsal inclination angle (p = .400) were not. The first intermetatarsal angle (p < .001), hallux valgus angle (p = .003), and proximal articular set angle (p = .015) were found to be independently associated with the tibial sesamoid position, while Engel's angle (p = .400), the first metatarsal inclination angle (p = .088), and the sesamoid rotation angle (p = .649) were not. These findings appear to question a direct relationship between the first intermetatarsal angle and hallux valgus angle, as well as potentially infer a relationship between the frontal plane with the hallux valgus angle.

Multivariate Analysis of Hallux Valgus Radiographic Parameters

This investigation aimed to better understand the complex relationship of common radiographic measurements performed during the perioperative evaluation of the hallux valgus deformity while accounting for interactions and potential interdependence. Several analyses utilizing the first intermetatarsal angle, hallux valgus angle, tibial sesamoid position, Engel's angle, subject age and subject gender were performed with varying independent and dependent variables. The hallux valgus angle (p < .001), tibial sesamoid position (p < .001), and Engel's angle (p < .001) were found to be independently associated with the first intermetatarsal angle. The first intermetatarsal angle (p < .001), tibial sesamoid position (p < .001), and Engel's angle (p < .001) were found to be independently associated with the hallux valgus angle. This suggests that there is significant interdependence of these variables during a preoperative radiographic examination. However, only the change in tibial sesamoid position (p < .001) was found to be independently associated with the change in the first intermetatarsal angle following surgical correction, while no studied variables were found to be independently associated with the change in hallux valgus angle following surgical correction. This suggests that correction of the intermetatarsal angle and tibial sesamoid position might not always reliably predict correction of the hallux valgus angle following surgical intervention. It might also suggest that additional procedures beyond metatarsal osteotomies are required to reliably correct the hallux valgus angle in some deformities. It is hoped that this investigation adds to the body of knowledge with respect to the perioperative radiographic evaluation of the hallux valgus deformity.

The Rotational Effect of Scarf Osteotomy With Transarticular Lateral Release on Hallux Valgus Correction

The purpose of this study was to explore the rotational effect of scarf osteotomy with transarticular lateral release (TALR) on hallux valgus correction. From January 2016 to January 2018, 28 consecutive patients (30 feet) were included in this study. The first intermetatarsal angle (IMA), hallux valgus angle (HVA), and round-shaped lateral edge of the first metatarsal head (R sign), and sesamoid rotation angle (SRA) were recorded prior to and 3 months after the surgery. The rotation of the capital fragment of the first metatarsal was termed the capital rotation angle (CRA) and was measured intraoperatively after the completion of scarf osteotomy. The IMA, HVA, and SRA were significantly reduced from 13.9 ± 4.9°, 34.6 ± 7.4°, and 28.7 ± 9.8° to 2.4 ± 2.3°, 7.3 ± 4.7°, and 13.4 ± 8.8°, respectively (p < .01 for all). The mean CRA was 7.0 ± 3.4° and was not significantly correlated with the reduction of IMA and SRA (p > .05 for all); nor was it significantly correlated with IMA preoperatively and postoperatively (p > .05 for all) or the reduction of SRA and IMA (p > .05). The R sign was positive in 40% (12/30) of the feet preoperatively compared to 13.3% (4/30) postoperatively (p < .001). Scarf osteotomy produced a supination effect on the capital fragment of the first metatarsal and supinated the sesamoids via lateral translation of the first metatarsal head. These changes may contribute to the correction of the pronation component of hallux valgus deformity.

Comparison of Radiographic Measurements Before and After Triplane Tarsometatarsal Arthrodesis for Hallux Valgus

We present a comparison of preoperative and final postoperative first ray measurements in 109 feet after triplane tarsometatarsal arthrodesis at a mean follow-up time of 17.4 months. Preoperative and final postoperative first ray variables including intermetatarsal angle (IMA), hallux valgus angle (HVA), tibial sesamoid position (TSP), distal metatarsal articular angle (DMAA), Seiberg index, metatarsal rotation angle (MRA), sesamoid subluxation, osseous union, and hardware failure were evaluated. Measurements were made by consistently using the mid-diaphyseal line of the bone segments for both preoperative and postoperative assessments. The mean preoperative HVA, IMA, and TSP were 22.9°, 13.3°, and 4.6. The mean differences (95% confidence interval) in preoperative and postoperative values were -14.9° (-16.3° to -13.4°) for HVA, -7.7° (-8.2° to -7.2°) for IMA, and -2.6 (-2.8 to -2.3) for TSP. Among bunions with MRA measurements, the mean difference was -12.3° (-14.5° to -10.0°). The preoperative to postoperative DMAA decreased by a mean of -14.2° (-15.9° to -12.6°). The results of this study suggest that triplane tarsometatarsal arthrodesis produces appropriate correction of hallux valgus radiographic parameters.

Triplanar Chevron Osteotomy: A Newly Proposed Method to Treat Hallux Valgus Deformities

Objective

To present a novel method called triplanar chevron osteotomy to treat hallux valgus (HV).

Methods

This is a retrospective study. In this study, the CT data of HV patients with painful callosities were evaluated retrospectively between 1 June 2018 and 1 June 2020. CT data from 49 consecutive patients (59 feet) with HV were evaluated. The average age at the time of surgery was 49.6 years (range, 30–63 years). The apex of the chevron osteotomy procedure was located at the center of the first metatarsal and was defined as the line formed by the central point perpendicular to the fourth metatarsal bone. The cut planes of the plantarward oblique chevron osteotomy (POCO) were defined as follows: chevron osteotomy along with 20° of plantarward obliquity. The triplanar osteotomy incision was made using the POCO method, with the direction inclined by 10° distally. The intermetatarsal angle (IMA), the HV angle (HVA), the projection of the second metatarsal (PSM), the metatarsal protrusion index (MPI), and the metatarsal protrusion distance (MPD) were all calculated before and after the operations. The length of the first metatarsal was measured and calculated with an equation.

Results

The results showed that the HVA was significantly decreased after surgery (32.7° ± 4.6° vs 14.9° ± 2.1°, t = 25.583, P < 0.001) in the triplanar, traditional, and POCO groups. The IMA was also significantly decreased (14.7° ± 2.0°) compared with the results before surgery (8.0° ± 1.1°, t = 22.739, P < 0.001) in these groups. Compared with traditional osteotomy and POCO, there were no differences in correcting deformities on axial planes for the HVA (14.5° ± 1.7° vs 14.9° ± 2.1°, t = 1.835, P = 0.072) and IMA (8.1° ± 1.1° vs 8.0° ± 1.1°, t = −0.97, P = 0.336). There was a statistically significant decrease following surgery in terms of the PSM, MPI, and MPD after triplanar osteotomy. The length of the first metatarsal increased (10.9 ± 1.3 mm), as measured through three‐dimensional images in the triplanar osteotomy group. The length was calculated as follows: H = L2 * Tan θ ≈ L/COS β * Tan θ.

Conclusion

The new triplanar osteotomy technique is safe and effective for treating HV, and in simulation experiments reveals potential benefits of correction and preventing transfer metatarsalgia.