Relationship of frontal plane rotation of first metatarsal to proximal articular set angle and hallux alignment in patients undergoing tarsometatarsal arthrodesis for hallux abducto valgus: a case series and critical review of the literature

A New Paradigm in Foot and Ankle Outcomes?: Away From Radiographs and Toward Patient-Centered Outcomes

Having reasonable outcome measures is essential to unbiased research. For years, provider-measured outcomes have been valued as they are more objective and convenient for investigators. However, with the popularity of patient-centered medical care delivery, patient-reported outcome measures are appropriately becoming more popular in foot and ankle research.

The Lapidus Bunionectomy Revolution: Current Concepts and Considerations

Hallux valgus is a common foot deformity in which many surgical techniques have been introduced. Originally, Paul Lapidus detailed a midfoot arthrodesis technique to address the deformity and medial column instability that served as the foundation for the modified Lapidus bunionectomy. The appreciation of the multiplanar nature of hallux valgus deformity continues to evolve and helps to guide the investigation of the ideal surgical correction to yield more predictable results and reduced complications. Various fixation constructs have been used over the years for the Lapidus bunionectomy without a clear superior fixation technique, and literature supports early weight-bearing with each.

Morphology variations with medial cuneiform in hallux valgus

The hypermobility of the first tarsometatarsal joint has been identified as a key factor in the development of hallux valgus. Previous research found a link between the tarsometatarsal joint obliquity and the hallux valgus angle. Nevertheless, most studies relied on radiographs that lack 3D evidence. This study used 3D analysis to investigate the morphological differences in the medial cuneiform between hallux valgus and normal feet. In this study, twenty-three hallux valgus feet and twenty-three normal feet were scanned with computed tomography and 3D models of medial cuneiforms were reconstructed. Medial cuneonavicular and the first tarsometatarsal joint surfaces of the medial cuneiform were manually extracted. To obtain the obliquity angle of the medial cuneiform and curvature of the medial cuneonavicular joint, the joint surfaces were approximated to planes and spheres. Furthermore, the orientations of two joint surfaces were accessed through a novel positioning method. No significant difference was found in the cuneiform obliquity between hallux valgus and normal feet. Hallux valgus and normal groups did not differ significantly in any of the medial cuneiform joint orientations. The medial cuneiform in hallux valgus had a larger curvature diameter of the medial cuneonavicular joint (P = 0.029), indicating a flatter surface. The results demonstrated that the generally supported atavism (i.e., tarsometatarsal joint obliquity) does not exist in the hallux valgus feet. A flatter medial cuneonavicular joint surface was found in hallux valgus feet. This study contributes to the comprehensive understanding of the etiological factors with hallux valgus.

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.

Rates of Lapidus Procedures in the US Military Before and After the Advent of and Advocacy for Tri-Plane Lapidus Corrective Surgery

Tri-plane corrective Lapidus surgery has been described as advantageous with respect to its anatomic basis and outcomes. Because the procedure has been broadly publicized, changes in overall Lapidus procedure rates due to increased numbers of patients opting for the tri-plane approach could have occurred. Data supporting this possibility appears lacking. We employed official personnel and health records of the total active-duty US military to conduct a retrospective cohort study of Lapidus surgery rates before and after the advent of the tri-plane corrective Lapidus procedure. Least-squares and locally-weighted scatterplot smoother regression functions were used to confirm time trends. Sociodemographic and occupational traits of Lapidus patients were compared using 2-sided t tests and chi square tests. Lapidus surgery rates among hallux valgus patients decreased during 2014 to 2016 and increased during 2017 to 2021. While multiple factors might explain these trends, they coincide with the advent of and advocacy for tri-plane Lapidus surgery. The results support the possibility that its rise influenced overall Lapidus rates in this population. As these findings represent limited evidence of such an influence, further research is required to confirm a causal link. If such a link is found, and if the ongoing research suggests that superior outcomes are associated with tri-plane Lapidus surgery, substantial implications could exist for this population. Benefits might include enhanced medical readiness due to the importance of lower extremity function during military duties. Additional research is needed to confirm the impact of the procedure and to determine whether Lapidus surgery rate patterns in civilian populations mirror these findings.

Investigation on the site of coronal deformities in Hallux valgus

Hallux valgus (HV) is a common foot deformity that is more prevalent in females, characterised by abnormal adduction of the first metatarsal (MT) and valgus deviation of the phalanx on the transverse plane. Increasing evidence indicates that HV is more than a 2D deformity but a 3D one with rotational malalignment. Pronation deformity is seen during clinical examination for HV patients, but the exact origin of this rotational deformity is still unknown. Some attribute it to first tarsometatarsal (TMT) joint rotation, while others attribute it to intra-metatarsal bony torsion. In addition, the correlation between the rotational and transverse plane deformity is inconclusive. Identifying the origin of the rotational deformity will help surgeons choose the optimal surgical procedure while also enhancing our understanding of the pathophysiology of HV. This study aims to (1) develop an objective method for measuring the first MT torsion and first TMT joint rotation; (2) investigate the exact location of the coronal deformity in HV; (3) investigate the relationship between the severity of deformity on the transverse and coronal planes as well as the correlation between deformity severity and foot function/symptoms in HV. Age-matched females with and without HV were recruited at the Foot and Ankle Clinic of the Department of Orthopaedics and Traumatology. Computed tomography was conducted for all subjects with additional weight-bearing dorsal-plantar X-ray examination for HV subjects. Demographic information of all subjects was recorded, with symptoms and functions related to HV evaluated. The intra-class correlation was used to explore the relationship between deformities on different planes and the deformity severity and functional outcomes, respectively. An Independent t-test was used to compare joint rotation and bone torsion degrees. TMT joint rotation is significantly correlated with foot function. HV patients had more TMT joint rotation but not MT torsion compared to normal controls. No relationship was found between the coronal rotation and the 1,2-intermetatarsal angle (IMA) or Hallux valgus angle (HVA) on the transverse plane. Our results indicate that coronal deformities in HV may originate from TMT joint rotation. In addition, the severity of the TMT joint coronal rotation correlates with worse foot function; thus, multi-plane assessment and examination will be necessary for more precise surgical correction.

Mechanical Axis Method to Determine First Intermetatarsal Angle and Tibial Sesamoid Position

Utilizing the mechanical axis can decrease load on the joint and be beneficial when analyzing bony deformities and planning surgical correction with osteotomies. The aim of this study was to identify the normal mechanical axes of the first and second metatarsals and use them to obtain the first/second mechanical intermetatarsal angle (mIMA). The mechanical axis of the first metatarsal was used to obtain the mechanical tibial sesamoid position (mTSP), which provides a mechanical relationship with the sesamoid apparatus. The angular difference between the anatomic and mechanical axis lines (anatomic-mechanical angle [AMA]) was determined for the first metatarsal and for the second metatarsal. The commonly used first/second anatomic intermetatarsal angle (aIMA) and anatomic tibial sesamoid position (aTSP) were also obtained and compared with the first/second mIMA and mTSP. In this retrospective analysis, radiographs of 50 normal feet (40 patients) were assessed. Pearson's correlation coefficients were used to measure reliability between obtained measurements. Mean first/second aIMA was 8.6 ± 3.0 degrees, and first/second mIMA was 8.6 ± 2.6 degrees. First metatarsal AMA was 1.1 ± 1.0 degrees; second metatarsal AMA was 2.0 ± 1.6 degrees. The mTSP was 2.8 ± 1.1, and aTSP was 2.9 ± 1.0. The TSP median was 3 (range, 1-5). Using the mechanical axis method to obtain the first/second mIMA and the mTSP is reproducible and not affected by anatomic changes to the shape of the metatarsal. Unlike the anatomical axis, the mechanical axis does not change, therefore we recommend using the mechanical axis during surgical planning and when obtaining preoperative and postoperative measurements for the long bones of the foot, particularly for forefoot conditions such as hallux valgus.

Radiological and Anatomical Evaluation of First Metatarsal Pronation in Hallux Valgus Deformity: A Comparison Between Three Different Methods

A frontal plane metatarsal rotational (pronation) has been documented in a high percentage of hallux valgus patients. Pathoanatomical concepts leading to pronation are still debated. Nevertheless, there is no consensus on how to measure this component of the deformity. The aim of the present study was to compare three commonly used radiographic methods to measure the frontal plane deformity in hallux valgus deformity, such as 1. Round sign of the lateral edge of the first metatarsal head on anterior-posterior radiograph, 2. Non-weightbearing CT-scan and 3. Bernard's axial projection of the first metatarsal head. Afterwards, feet were dissected, and a direct measurement of the pronation was done. Our data showed that alpha angle measurements made through the Bernard's axial projection were closer with those obtained during the dissection compared to those made through the CT-scan. The main finding of our study is that osteoarthritic changes at the metatarso-sesamoid joint play an important role in severe hallux valgus cases. The proposed radiographic methods allow surgeons to verify whether rotation can be corrected during Hallux Valgus procedures and to determine which procedure may be the best for each patient.

First Tarsometatarsal Joint Arthrodesis for Hallux Valgus With and Without Intermetatarsal Screw Fixation: A Comparison of Correction and Maintenance of Correction

Tarsometatarsal joint arthrodesis is a commonly accepted procedure for hallux valgus associated with severe deformity and first ray hypermobility or medial column instability. This study evaluates the correction of hallux valgus deformity and the maintenance of correction with and without the use of a stabilization screw between the first and second metatarsal bases. Through retrospective review of first tarsometatarsal joint arthrodesis within our institution we evaluated 63 patients. Twenty-seven patients did not have a first to second metatarsal base screw and were placed into the no screw cohort. Thirty-six patients did have a first to second metatarsal base screw and were placed into the screw cohort. This study population had an osseous union rate of 95%. Clinical and radiographic recurrence occurred in 5 of 63 patients (8%). At 1-y postop the measurements demonstrated that the screw cohort had an average intermetatarsal angle correction of 11.6 degrees while the no screw cohort had an average correction of 7.8 degrees. Additionally, at 1-y postop the screw cohort had greater maintenance of the intermetatarsal angle correction with an average change of 0.5 degrees compared to 2.3 degrees in the no screw cohort. We conclude that the addition of the stabilization screw improves the first tarsometatarsal joint arthrodesis construct resulting in a greater degree of realignment and maintenance of correction.

The Effect of Hallux Valgus Surgery on the Transverse Plane Hallux Proximal Phalanx Position

The objective of this investigation was to evaluate the apparent movement of the hallux proximal phalanx in the transverse plane relative to the second metatarsal following hallux valgus surgery. Pre- and postoperative radiographs of a consecutive series of 45 feet undergoing hallux valgus surgery were analyzed. Significant improvements were observed in the first intermetatarsal angle (12.4 vs 7.5 degrees; p < .001), hallux valgus angle (24.3 vs 13.4 degrees; p < .001), tibial sesamoid position (4.6 vs 2.7; p < .001), and second metatarsal-hallux proximal phalanx angle (80.1 vs 84.6 degrees; p < .001). No difference was observed in the distance between the second metatarsal bisection and the medial aspect of the tibial sesamoid (31.7 vs 31.5 mm; p = .756) nor between the second metatarsal bisection and medial aspect of the hallux proximal phalanx base (34.6 vs 34.2 mm; p = .592). Significant differences were observed between the second metatarsal bisection and the central aspect of hallux proximal phalanx base (26.5 vs 23.9 mm; p < .001) and between the second metatarsal bisection and the lateral aspect of the hallux proximal phalanx base (19.3 vs 15.4 mm; p < .001). A statistically significant difference was observed in the change of distance between the second metatarsal bisection and the medial, central, and lateral aspects of the hallux proximal phalanx base (-0.4 vs -2.6 vs -3.9 mm; p = .002). These results indicate that the hallux proximal phalanx does not translocate in the transverse plane following hallux valgus surgery, but instead pivots about the medial aspect of the joint.

The Improved Proximal Phalanx Osteotomy for Reducing Sesamoid in Hallux Valgus Surgery-A Cadaver Study

A metatarsal osteotomy is known to have the effect of reduction of the sesamoid. However, the reduction of the sesamoid is not always completed by a metatarsal osteotomy alone. The purpose of this cadaver study was to show that the improved technique of a modified Akin proximal phalanx osteotomy (MPO) could be helpful for the reduction of the sesamoids in hallux valgus surgery. Ten feet of cadavers were used; the cadavers had hallux valgus on both feet. The first trial of two feet underwent only the MPO. The other eight feet underwent a proximal metatarsal chevron osteotomy and MPO simultaneously. The hallux valgus angle, intermetatarsal angle, Hardy’s grade, and Smith’s grade were measured. To predict possible complications, cadavers were dissected after surgery. In the feet that underwent an MPO only, the hallux valgus angle and sesamoid position were improved. In the feet that underwent an MPO and metatarsal osteotomy, the hallux valgus deformity was completely corrected, and the sesamoid position was improved. Overall, the hallux valgus angle and intermetatarsal angle improved from 30.6 to 8.4 degrees and from 11.2 to 4.1 degrees, respectively. The sesamoid position was reduced from 5.3 to 2.5 (Hardy) and from 1.7 to 0.7 (Smith). The MPO combined with the metatarsal osteotomy were helpful for reducing the sesamoids compared to the metatarsal osteotomy only.

Lapidus Arthrodesis

There has been significant enhancement in surgical management of hallux valgus deformity. Recognition of the role of medial column hypermobility has resulted in better functional outcomes with decreased risk of recurrence. Modern techniques have evolved to include enhanced fixation in a move toward minimal postoperative downtime. Evolution to include true triplane correction, including frontal plane derotation of the first ray, has resulted in optimal functional outcomes. The addition of anatomic triplane restoration, enhanced internal fixation, and early return to weight-bearing activities are combined resulting in lifelong correction with excellent functional outcomes and a high degree of patient satisfaction.

First-Ray Radiographic Changes After Flexible Adult Acquired Flatfoot Deformity Correction

BACKGROUND

Adult acquired flatfoot deformity (AAFD) and hallux valgus (HV) are common foot and ankle deformities. Few studies have reported the changes in radiographic parameters of HV after reconstructive surgery for AAFD. This study aimed to evaluate the changes in radiographic parameters of HV and analyze the risk factors for increased HV after correction of AAFD.

METHODS

Adult patients with flexible AAFD who underwent similar bony procedures including medializing calcaneal osteotomy and Cotton osteotomy were included. Radiographic parameters were measured on weightbearing radiographs preoperatively, postoperatively, and at the final follow-up. Patients were divided into hallux valgus angle (HVA) increased and HVA nonincreased groups; logistic regression analysis was performed to identify risk factors affecting increased HV.

RESULTS

Forty-six feet of 43 patients were included. After AAFD reconstructive surgery, the tibial sesamoid position improved by 1 grade, but the HVA increased 4 degrees in average. Further, 21 of 46 feet (46%) showed an HVA increase ≥5 degrees immediately after AAFD correction surgery. Preoperative talonavicular coverage angle <21.6 degrees was a risk factor associated with HV increase immediately after the surgery.

CONCLUSION

In this case series, using plain radiographs to measure standard parameters of foot alignment, we found the association between AAFD correction and HV deformity measures somewhat paradoxical. Correction of overpronation of the hindfoot and midfoot appears to improve the first metatarsal rotational deformity but may also increase HVA. A lower preoperative talonavicular coverage angle was associated with an increase of the HVA after surgery.

LEVEL OF EVIDENCE

Level IV, case series study.

The Realign-Resect Arthrodesis Technique

During traditional fusion procedures surgeons initially perform a joint resection and then the structures are realigned for correction of deformity. The procedure described herein by the author reverses this traditional surgical approach by first realigning the joint to correct deformity, then after achieving a corrected alignment, joint resection is performed in parallel without wedging. Realigning deformity as an initial step creates the conditions for an in-situ fusion wherein the deformity is corrected simultaneously with parallel bone resection. The purpose of this paper is to review the advantages and technical aspects of a realignment arthrodesis technique in which joint resection begins with the foot in the corrected position. This approach to joint fusion has been shown to simplify bone resection, eliminate post-resection adjustments, create full apposition of fusion surfaces, reliably correct deformity, and result in solid arthrodesis. The technique provides for immediate correction of deformity and is amenable for conditions that require either minimal or significant segmental shortening. There are many areas where the "Realign-resect" approach to joint fusion would be well suited. Full implementation of this technique may be particularly useful to the surgeon who does not have seasoned assistants in the operating room.

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.

First Metatarsal Rotation in Hallux Valgus Deformity

Rotation of the first metatarsal (M1) as a potential etiological factor of hallux valgus (HV) deformity was described relatively early in the description of HV pathoanatomy. However, because biplanar radiographs have been the standard method for imaging HV, clinicians primarily developed measurement methods and corrective operations confined to 2 dimensions, medial-lateral and inferior-superior. Recently, as our understanding of HV pathoanatomy has further developed, aided in part by advanced imaging technology, M1 rotation about its axis ("axial rotation") and its implications for HV deformity and treatment has reemerged. The goal of this review is to summarize M1 rotation in HV from a historical perspective, to present the current understanding of its potential role in the etiology/pathogenesis of HV, and to summarize relevant imaging and operative considerations with respect to M1 rotation.Level of Evidence: Level III, systematic review.

Inaccuracy of Forefoot Axial Radiographs in Determining the Coronal Plane Angle of Sesamoid Rotation in Adult Hallux Valgus Deformity: A Study Using Weightbearing Computed Tomography

BACKGROUND

Hallux abducto valgus is a triplane deformity with recent attention given to the significance of correcting the coronal plane component. This study explored the accuracy of the forefoot axial (FFA) study as a standard radiographic assessment method compared with weightbearing computed tomography (CT).

METHODS

Twelve feet with hallux abducto valgus from 12 individuals were included in this study. Three images of the affected foot were taken: FFA radiograph and weightbearing CT with the foot in maximum pronation (pronated CT) and maximum supination (supinated CT). Five investigators determined the sesamoid rotation angles (SRAs) from each of the images. The measurements from a single investigator were used to compare the SRA means from each of the image types, and those from all five investigators were used to determine reliability.

RESULTS

The mean ± SD SRA was 22.1° ± 7.6° for pronated CT, 10.5° ± 5.0° for supinated CT, and 12.2° ± 9.4° for FFA images. The mean SRA from the pronated CT was significantly greater than the supinated CT (P < .001) and FFA (P < .005) SRAs. There were no significant differences in mean SRA between the FFA and supinated CT images (P > .99). Results indicated high reliability in measurements among investigators.

CONCLUSIONS

Using weightbearing CT, these findings indicate that the sesamoids significantly alter their position in the coronal plane, as determined by the SRA, with changes in weightbearing subtalar joint position. Moreover, the affected foot positioning required for determining the SRA from the FFA radiograph seems to significantly underestimate the true SRA. Thus, use of this image in surgical hallux abducto valgus planning is called into question.

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.

Fixation Principles in Minimal Incision Hallux Valgus Surgery

Minimal incision surgical principals rely on the soft tissue envelope to maintain stability that is supplemented by a variety of clinically recommended fixation methods. The extended distal first metatarsal osteotomy has renewed interest because of the ability to laterally translate, angulate, and rotate the metatarsal head in proper alignment with the sesamoids to a neutral alignment. The soft tissue envelope of capsule, ligaments, and tendons will re-align once the bone deformity is corrected. The periosteum is maintained to provide a biologic scaffold for new bone formation and must be minimally disrupted during the intervention."

Intraoperative and Postoperative Evaluation of Hallux Valgus Correction: What Is Important?

The hallux valgus is one of the most challenging foot and ankle deformities to correct. The current concept is to consider the hallux valgus as a triplane deformity, and the parameters in transverse, sagittal, and frontal planes must be considered. The hallux valgus angle, intermetatarsal angle, tibial sesamoid position, and lateral edge of the first metatarsal head are valuable parameters to evaluate to understand the magnitude of the deformity. Diaphyseal corrections, such as scarf, and proximal interventions, such as crescentic osteotomy and Lapidus arthrodesis, are the most powerful techniques to address triplane deformity, because they are able to correct all misalignments.

Evolution of Thinking of the Lapidus Procedure and Fixation

The evolution of Lapidus fixation has been strongly associated with the understanding of the anatomy and function of the first tarsometatarsal joint, the mechanism of hypermobility of the first tarsometatarsal joint, and cause of the hallux valgus deformity in 3 dimensions. Some methods, such as plantar plating, nitinol staples, and intramedullary fixation, have proven to be stronger biomechanically in cadaveric testing. Theoretically, stable fixation will reduce the rate of complications, in particular, that of nonunion and allow for early postoperative weight-bearing. Further clinical studies are needed to examine whether current biomechanical studies will translate to relevant clinical outcomes.

Three-Dimensional Analysis of the First Metatarsal Bone in Minimally Invasive Distal Linear Metatarsal Osteotomy for Hallux Valgus

BACKGROUND

Modified Bösch osteotomy (distal linear metatarsal osteotomy [DLMO]) is one of the minimally invasive correctional surgeries for hallux valgus. The 3-dimensional correctional angles and distances of the first metatarsal bone in DLMO have not been clarified. The purpose of this study was to analyze the 3-dimensional postoperative morphological changes of the first metatarsal bone in DLMO.

METHODS

Twenty patients (30 feet) who underwent DLMO were enrolled. Preoperative plain radiographs and computed tomography (CT) scans of the feet were examined. Postoperative radiographs and CT scans were also obtained after bone union. The surface data of the pre- and postoperative first metatarsals were reconstructed from the CT data. The positions of the distal ends of the first metatarsals described with respect to the proximal ends were calculated using CT surface-matching technique.

RESULTS

The distal end of the first metatarsal after DLMO was significantly supinated (10.2 ± 6.0 degrees, P < .001), adducted (6.0 ± 11.8 degrees, P = .004), dorsiflexed (11.1 ± 10.9, P < .001), shortened (7.4 ± 2.5 mm, P < .001), elevated (2.3 ± 3.1 mm, P = .001), and laterally shifted (8.2 ± 3.0 mm, P < .001) compared to the preoperative metatarsal distal end. Supination correction demonstrated a significant correlation with adduction correction (r = 0.659, P < .001) on correlation analyses between these parameters.

CONCLUSION

The 3-dimensional corrections of the first metatarsal bone after DLMO were evaluated. Pronation and abduction were successfully corrected. Furthermore, adduction correction might be an important factor affecting correction of pronation.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Incidence of hallux valgus primary surgical treatment. Finnish nationwide data from 1997 to 2014

BACKGROUND

Many surgical procedures have been described for hallux valgus. Evidence provided by the current literature on the different procedures is, however, poor. The purpose of this study was to assess the incidence of HV surgery in Finland between 1997 and 2014 and to find out whether changes in operation techniques of HV have occurred during the study period.

METHODS

The study included all adult patients (≥18 years) who underwent primary HV operation. Patients were included into study if they had been operated with a diagnosis of HV (ICD-10 code M20.1). The data were collected by the Finnish National Hospital Discharge Register (NHDR).

RESULTS

The total incidence of primary HV operations was 66.7 per 100,000 person-years in 1997 and 41.4 per 100,000 person-years in 2014. The incidence of arthroplasty operations of the MTP-1 joint decreased while at the same time the incidence of the MTP-1 joint arthrodesis and TMT-1 arthrodesis increased. The gender difference (13% men, 87% women) is consistent with previous studies.

CONCLUSION

This study shows a significant decreasing trend of HV operations in Finland between 1997 and 2014. During the study period, the incidence of MTP I joint arthroplasty decreased, and since 2005 the incidence of MT-1-osteotomies has almost halved. At the same time, the incidence of MTP-1 joint arthrodesis increased by over 1000% and TMT-1 joint arthrodesis by nearly 2000%.

Relationships Between First Metatarsal and Sesamoid Positions and Other Clinically Relevant Parameters for Hallux Valgus Surgery

Relationships between hallux valgus (HV) and other measurements within the first ray have been extensively studied. It is becoming more popular to correct HV deformity with tarsometatarsal joint arthrodesis while internally (varus) rotating the first metatarsal. This, in turn, reduces the sesamoid position when viewed in the dorsoplantar projection on radiographs. However, it has been shown that not all HV deformities have pathological external (valgus) rotation of the first metatarsal. In this study, we explored the relationships between frontal-plane rotations of the first metatarsal as well as the sesamoids, and other factors not limited to the first ray, to better understand the pathological process of HV deformity and to assist in surgical planning. We found that when adjusting for these covariates, the only factor associated with first metatarsal external rotation was having less metatarsus adductus. Sesamoid rotation, on the other hand, was independently associated with the HV angle, tibial sesamoid position, and medial column collapse. When surgically treating HV, correction of sesamoid rotation may need to be prioritized.

Can We Abandon Saw Wedge Resection in Lapidus Fusion? A Comparative Study of Joint Preparation Techniques Regarding Correction of Deformity, Union Rate, and Preservation of First Ray Length

The traditional joint preparation technique for Lapidus fusion involves wedge resection using a saw to achieve correction of intermetatarsal angular deformity. The main drawback of this approach is undesirable shortening of the first ray, which can predispose to second ray overload that may preclude the procedure for a subset of patients or may necessitate second metatarsal shortening osteotomy. The goal of this study was to determine whether a first ray length-preserving joint preparation technique (curette and bur) achieves equivalent correction of deformity and fusion rate without first ray shortening compared with the standard saw wedge resection technique. A retrospective review of consecutive cases from January 2007 to August 2014 identified 62 patients who underwent 65 Lapidus fusions for hallux valgus correction with crossed-screw fixation. All patients treated from 2007 to 2010 had saw wedge resection, whereas all patients treated from 2011 to 2014 had curette and bur joint preparation without use of a saw. The mean intermetatarsal angle correction was 9.06° (range 5° to 14.7°) in the saw wedge resection group and 8.11° (range 2.8° to 15.5°) in the curette and bur group, a difference that was not statistically significant. The mean amount of first ray shortening was -3.14 (range -6.1 to 0) mm in the saw wedge resection group and -0.86 (range -2.3 to 4.2) mm in the curette and bur group, a result that was statistically significant. Osseous union was confirmed radiographically at 10 weeks postoperatively in all cases. These findings suggest that first ray length can be preserved using a more conservative joint preparation technique regardless of preoperative deformity, without compromising correction of deformity or union rate.

Hallux Pronation in Hallux Valgus: Experimental and Radiographic Study

Toe pronation is a frequent sign in hallux valgus (HV), but it is difficult to assess and quantify. The aim of this study was to evaluate the relation between big toe pronation with both radiological and clinical findings and to determine if toe pronation is an influential factor in severity of HV. Six big toe donor proximal phalanges were used to create a radiographic calibrating system controlling their pronation at 0° to 60°. A linear regression model was used to predict proximal phalanx pronation in radiographs. Big toe pronation in HV was clinically evaluated with a prospective study using 132 patients from our surgical waiting list and a control group of 30 patients without HV. Patients standing barefoot on a rigid platform were used to obtain the nail-floor angle. We obtained the following angles: HV, intermetatarsal, interphalangeal, distal articular set angle, proximal articular set angle, first metatarsal pronation, proximal phalanx pronation, and sesamoid bones displacement. We obtained an equation to predict proximal phalanx pronation according to the proportion of the rotated phalanx (p < .001, r = 0.98), and used an intraclass reliability test to assess the intra-/interobserver reliability (p < .001, intraclass correlation [ICC] = 0.89/p < .001, ICC = 0.82). We found that the relation between HV severity and proximal phalanx pronation, nail-floor angle, and first metatarsal pronation was statistically significant (p < .0001, r = 0.64). Proximal phalanx pronation and nail-floor angle should be considered to classify the severity of HV. Using a mathematical formula, we can predict proximal phalanx pronation on radiographs. Clinical Level of Evidence.

Establishing a common instantaneous center of rotation for the metatarso-phalangeal and metatarso-sesamoid joints: a theoretical geometric model based on specific morphometrics

BACKGROUND

Previous research has identified separate sagittal plane instantaneous centers of rotation for the metatarso-phalangeal and metatarso-sesamoid joints, but surprisingly, it does not appear that any have integrated the distinctive morphological characteristics of all three joints and their respective axes into a model that collectively unifies their functional motions. Since all joint motion is defined by its centers of rotation, establishing this in a complicated multi-dimensional structure such as the metatarso-phalangeal-sesamoid joint complex is fundamental to understanding its functionality and subsequent structural failures such as hallux abducto valgus and hallux rigidus.

METHODS

Based on a hypothesis that it is possible to develop an instantaneous center of rotation common to all four osseous structures, specific morphometrics were selected from a sequential series of 0.5-mm sagittal plane C-T sections in one representative cadaver specimen randomly selected from a cohort of nine, seven which were obtained from the Body Donation Program, Department of Anatomy, University of California, San Diego School of Medicine, and two which were in the possession of one author (MD). All mature skeletal specimens appeared grossly normal, shared similar morphological features, and displayed no evidence of prior trauma, deformity, or surgery. Specific C-T sections isolated the sagittal plane characteristics of the inter-sesamoidal ridge and each sesamoid groove, and criteria for establishing theoretical sesamoid contact points were established. From these data, a geometric model was developed which, to be accurate, had to closely mimic all physical and spatial characteristics specific to each bone, account for individual variations and pathological states, and be consistent with previously established metatarso-phalangeal joint functional motion.

RESULTS

Sequential sagittal plane C-T sections dissected the metatarsal head from medial to lateral and, at approximately midway through the metatarsal head, the circular nature of the inter-sesamoidal ridge (crista) was isolated; other C-T sections defined, respectively, the elliptical characteristics of the tibial (medial) and fibular (lateral) sesamoid grooves in each specimen. A general plane model representing the most basic form of the joint was developed, and its center of rotation was established with a series of tangential and normal lines. Simplified tibial sesamoid and fibular plane models were developed next which, when combined, permitted the development of a spherical model with three separate contact points. Based on the morphometrics of each sesamoid groove and a more distally positioned tibial sesamoid, the model was modified to accurately define the center of rotation and one distinctive sagittal plane geometric and functional characteristic of each groove.

CONCLUSION

Consistent with our hypothesis, this theoretical geometric model illustrates how it is possible to define an instantaneous center of rotation common to all three joints while simultaneously accounting for morphometric and spatial variability. This should provide additional insight into metatarso-phalangeal-sesamoid joint complex functionality and the physical characteristics that contribute to its failure.

Triplane Hallux Abducto Valgus Classification

One of the most common procedures performed in the foot and ankle is correction of hallux abducto valgus deformity or "bunion surgery." Most foot and ankle surgeons recognize the challenges associated with defining each patient's individual deformity and selecting the optimal procedure for the best long-term results. Using current 2-dimensional algorithms that focus on the severity of the transverse plane deformity, surgical outcomes have varied. In the past 10 years, high recurrence and complication rates for popular procedures have been reported. In the same period, the reported data have elucidated an evolving anatomic understanding of the bunion deformity, with an expansion to 3 dimensions, including the frontal/coronal plane. We present a new classification and approach for the evaluation and procedure selection for bunion surgery. We hope this conceptual treatise on hallux abducto valgus based on clinical consensus and current data will stimulate academic discussion and further research. This anatomic classification is based on the 3-dimensional anatomy of the first ray.

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

Although hallux abductovalgus (HAV) is widely considered to be a triplanar deformity involving the transverse, sagittal, and frontal planes, most of the published literature has focused on evaluating the deformity in only the transverse plane, and we are unaware of any investigation objectively evaluating the relationship among the 3 planes in the setting of HAV deformity. The objective of this investigation was to quantitatively evaluate radiographic measurement of the relationship between the transverse, sagittal, and frontal planes in the HAV deformity. Anteroposterior, lateral, and sesamoid axial radiographs from 42 consecutive feet were evaluated with measurement of the first intermetatarsal angle, hallux abductus angle, metatarsal sesamoid position, first metatarsal inclination angle, sesamoid rotation angle, and tibial sesamoid grade. Variables were graphically depicted against each other on frequency scatter plots with calculation of a regression line and Pearson's correlation coefficient. As transverse plane deformity increased, the frontal plane deformity also tended to increase and the first metatarsal inclination angle tended to decrease. And as frontal plane deformity increased, the first metatarsal inclination angle tended to decrease. To our knowledge, these are the first quantitative and objective data in support of a triplanar component to the HAV deformity, and we believe this reinforces the evaluation of this deformity with emphasis on all 3 planes.

Association of Vitamin D Receptor Gene TaqI, BsmI, FokI, and ApaI Polymorphisms and Susceptibility to Hallux Valgus in the Chinese Population

Previous studies have indicated that vitamin D receptor (VDR) TaqI, BsmI, FokI and ApaI gene polymorphisms are associated with the risk of skeletal malformations with inflammation. However, the potential association of VDR gene polymorphisms with the susceptibility to hallux valgus remains unclear. To clarify this association, we compared the genotypes of 228 patients with hallux valgus with those of 200 controls using the Multiplex SNaPshot system. The χ² test was used to compare the allele and genotype frequencies between groups, and p ≤ .05 was considered statistically significant. The frequencies of the mutant allele C in TaqI (p= .036; odds ratio [OR] 1.57; 95% confidence interval [CI] 1.03-2.39) and mutant allele A in BsmI (p= .036; OR 1.33; 95% CI 1.02-1.74) were significantly greater in the patients than in the controls. In addition, after adjusting for sex and age, TaqI (p= .047; OR 1.61; 95% CI 1.00-2.58) and BsmI (p= .025; OR 1.67; 95% CI 1.06-2.61) were associated with the risk of hallux valgus through a dominant genetic model. A homozygous genetic model of BsmI was also significantly associated with the risk of hallux valgus (p= .033; OR 1.81; 95% CI 1.05-2.57). However, neither ApaI nor FokI were associated with increased susceptibility. To the best of our knowledge, we have reported for the first time that VDR gene TaqI and BsmI polymorphisms might contribute to the increased risk of hallux valgus in Chinese population.

The change of first metatarsal head articular surface position after Lapidus arthrodesis

BACKGROUND

The Lapidus procedure has been used for hallux valgus deformity correction since 1931. In some cases, the arthrodesis results in an unfavourable lateral inclination of first metatarsal head articular surface. The objective of our study was to evaluate the change of orientation of this articular surface in relation to the second metatarsal axis by comparing pre- and postoperative radiographs. The secondary target was to evaluate possible benefits of combination of Lapidus and Akin procedures in the reduction of hallux valgus deformity.

METHODS

We evaluated 449 pre- and postoperative radiographs of 134 operations from 2010 to 2015. Routinely used angle measurements were performed on all X-rays. A sum of tangential angle to the second axis and distal articular set angle values was chosen as the best indicator for the deformity correction success.

RESULTS

The mean value of these angles total was 5.2° ±9.3° before and 14.2° ±7.8° after the operation. In the group of patients, where the additional Akin osteotomy was used, the mean value was 5.3° ±8.4° before and 6.9° ±10.2° after the surgery. The mean difference in values between the two groups (with and without Akin procedure) was 7.3° of extra correction in favour of the group with the Akin osteotomy.

CONCLUSIONS

The mean worsening of the tangential angle after Lapidus operation was 6.1° ±6.9°, which counts for significant deterioration after a surgery. The Akin osteotomy was found to be a valuable addition to the Lapidus arthrodesis, which improves the position of articular surfaces in first metatarsophalangeal joint.

Comparison of Tibial Sesamoid Position on Anteroposterior and Axial Radiographs Before and After Triplane Tarsal Metatarsal Joint Arthrodesis

We reviewed the radiographic results of a group of patients who had undergone triplane correctional tarsometatarsal arthrodesis for symptomatic hallux abducto valgus with metatarsus primus abducto valgus. Of the 21 feet included in the present review, 17 (81%) displayed radiographic findings of metatarsal pronation preoperatively based on axial sesamoid views and positive lateral round sign on anteroposterior radiographs. At a mean follow-up period of 5.2 ± 1.6 months, a significant improvement in the tibial sesamoid position (TSP) on both anteroposterior (AP) and axial radiographs was measured. A negative metatarsal round sign, indicating correction of coronal plane metatarsal rotation, was observed in 20 of the 21 feet (95.2%) on AP radiographic evaluation. All 21 patients (100%) had obtained resolution of sesamoid subluxation on the sesamoid axial view at the final follow-up examination. The sesamoid axial position was consistently normal when the round sign was absent, and the TSP was in the normal range of 1 to 3 on the AP radiograph. Sesamoid subluxation from the normal position with the tibial sesamoid on or lateral to the crista was noted in 4 feet (19%) preoperatively and 0 feet postoperatively. This confirmed that lateral round sign of the first metatarsal head and a high TSP noted on the AP radiograph are both related to metatarsal pronation and can be corrected concurrently with coronal plane varus rotation of the first metatarsal as a part of the procedure.

Mobility of the First Ray in Patients With or Without Hallux Valgus Deformity: Systematic Review and Meta-Analysis

The hypermobility theory of the first ray is the reason for the popularization of procedures such as the modified Lapidus procedure involving arthrodesis of the first tarsal-metatarsal joint for correction of hallux valgus deformity. Although many studies have involved motion of the first ray in hallux valgus patients, the presence and clinical significance of hypermobility in the first ray remains controversial. We performed a systematic review and meta-analysis to evaluate the difference in the first ray range of motion between patients with or without hallux valgus deformity. The databases used for the present review included Ovid EMBASE, Ovid MEDLINE, CINAHL, and the Cochrane Database. We searched for comparative studies that had evaluated the motion of the first ray in patients with or without hallux valgus. After screening for inclusion and exclusion criteria, we identified 3 studies that were relevant to our study question. All 3 studies showed more first ray motion in the hallux valgus group. Our quantitative synthesis showed a mean difference in the range of motion of the first ray of 3.62 mm (95% confidence interval 2.26 to 4.98) between those with and without hallux valgus deformity. Thus, we found statistically significantly increased first ray motion in patients with hallux valgus deformity compared with those without hallux valgus deformity. However, the clinical significance of this small amount of increased sagittal plane motion as a response to or a cause of hallux valgus remains unanswered.

Proximal Supination Osteotomy of the First Metatarsal for Hallux Valgus

Postoperative recurrence of hallux valgus is a relatively common complication and is associated with unsatisfactory surgical outcomes. Risk factors for postoperative recurrence include a round lateral edge of the first metatarsal head (a positive round sign) and incomplete reduction of the sesamoids. These risk factors may relate to residual pronation of the first metatarsal following surgery. A novel technique of a proximal supination osteotomy, in which varus and pronation of the first metatarsal can be corrected simultaneously, can achieve significant correction in moderate or severe hallux valgus deformity and a low rate of hallux valgus recurrence.

Hallux Valgus Deformity and Treatment: A Three-Dimensional Approach: Modified Technique for Lapidus Procedure

In a hallux valgus deformity, the problem is deviation of the hallux at the metatarsophalangeal joint and of the first metatarsal at the tarsometatarsal joint. Although anterior-posterior radiograph findings have been prioritized, deviation in the other planes can substantially change visible cues. The modified technique for Lapidus procedure procedure, uses all 3 planes to evaluate and correct the deformity, making radiographic measurements less useful. Using a triplane framework and focusing on the apex of the deformity, all bunions become the same modified technique for Lapidus procedure can be performed regardless of the degree of deformity, always includes triplane correction, and deformity size becomes irrelevant.

Sesamoid Position in Hallux Valgus in Relation to the Coronal Rotation of the First Metatarsal

Hallux valgus (HV) is not a simple two-dimensional deformity but is instead a three-dimensional deformity that is closely linked to sesamoid position and first metatarsal (MT) pronation. HV may or may not be accompanied by sesamoid subluxation and/or first MT head pronation. Each of these scenarios should be assessed using weighted computed tomography scan preoperatively, and the necessary corrections should be performed accordingly.

Hallux Valgus/Medial Column Instability and Their Relationship with Posterior Tibial Tendon Dysfunction

Historically, bunions have focused on the coronal plane; however, there is tension and compression failure in the sagittal plane of the midfoot during arch collapse. Correction of all 3 planes of deformity, coronal, sagittal, and rotational, can be achieved in several ways. Taking a big picture of global foot mechanics by recognizing the common types of conditions associated with arch collapse, including hallux valgus deformities, can serve as a useful roadmap for navigating more complicated deformities where hallux valgus exists.

Comparison between Simple Radiographic and Computed Tomographic Three-Dimensional Reconstruction for Evaluation of the Distal Metatarsal Articular Angle

The hallux valgus is a pathologic condition in the forefoot that often causes pain and functional limitations. Assessing all deformity components, such as the distal metatarsal articular angle (DMAA) is essential to hallux valgus treatment. Nevertheless, interobserver agreement of DMAA is poor on plain radiographs. The present study compared computed tomographic (CT) 3-dimensional (3D) reconstruction with plain radiographic measurements for measuring the DMAA. We included 43 consecutive patients (77 feet), diagnosed with hallux valgus at the orthopedic outpatient clinic at Hospital de Clínicas de Porto Alegre (Porto Alegre, Brazil) from April 2014 to June 2015 in our prospective study. The DMAAs were measured by 2 observers using CT 3D reconstruction. The results were compared between observers and with the plain radiographic measurements using the concordance correlation coefficient and the Bland-Altman plot to determine the agreement between the 2 methods. The interobserver agreement of the CT 3D measurements was high (concordance correlation coefficient 0.90; p < .001). Significant agreement was found between the plain radiographic and CT measurements (concordance correlation coefficient 0.667; p < .001). The Bland-Altman plot showed that the difference between the plain radiographic and CT measurements increased when greater DMAA values were associated with the presence of metatarsal rotation. The interobserver agreement of DMAA measurements was greater on CT 3D reconstruction than on plain radiography. The poor interobserver agreement of the radiographic DMAA might have resulted from metatarsal rotation.

The relationship between the distal metatarsal articular angle and intersesamoidal crista: An osteological study

BACKGROUND

As hallux valgus (HV) progresses, the first metatarsal drifts medially and the subsequent lateral drift of the sesamoids results in intersesamoidal crista erosion. This study aimed to provide a novel method of assessing crista erosion and determine if there is a relationship between that erosion and an increase in the distal metatarsal articular angle (DMAA).

METHODS

The DMAA and size of the intersesamoidal crista was measured on the first metatarsals of 120 adult modern human individuals. There was an equitable spread of both sexes, a wide age range (18-88 years), from three South African population groups (Zulu, Sotho, "European"). The following non-metric features were observed: intersesamoidal crista appearance, metatarsal head shape, and first intermetatarsal facet. Correlation tests, t-tests and Analyses of Variance (ANOVA) were used to determine relationships between variables.

RESULTS

The Pearson correlation test showed no significant correlation between the DMAA and crista ratio (r=0.092, p=0.154, α=0.05). DMAA: there was a significant difference between sides (p=0.009), right side larger; there was a significant difference between Zulu and "European" samples (p=0.036) but not between "Europeans" and Sotho (p=0.270); and there was a slight positive correlation with an increase in age. Crista: there was a significant difference between the sexes (p=0.044), with females having less erosion.

CONCLUSIONS

There is no significant relationship between the DMAA and crista erosion. Severe cartilaginous erosion is present before osteological changes occur, and the unexpected result may be reflected in skeletal specimens in which no cartilaginous changes can be observed. A novel, experimental method of assessing HV in modern human skeletal material is proposed.

First Metatarsal Head and Medial Eminence Widths with and Without Hallux Valgus

BACKGROUND

Resection of the medial eminence in hallux valgus surgery is common. True hypertrophy of the medial eminence in hallux valgus is debated. No studies have compared metatarsal head width in patients with hallux valgus and control patients.

METHODS

We reviewed 43 radiographs with hallux valgus and 27 without hallux valgus. We measured medial eminence width, first metatarsal head width, and first metatarsal shaft width in patients with and without radiographic hallux valgus.

RESULTS

Medial eminence width was 1.12 mm larger in patients with hallux valgus (P < .0001). Metatarsal head width was 2.81 mm larger in patients with hallux valgus (P < .001). Metatarsal shaft width showed no significant difference (P = .63).

CONCLUSIONS

Metatarsal head width and medial eminence width are significantly larger on anteroposterior weightbearing radiographs in patients with hallux valgus. However, frontal plane rotation of the first metatarsal likely accounts for this difference.

The influence of the Peroneus Longus muscle on the foot under axial loading: A CT evaluated dynamic cadaveric model study

BACKGROUND

Subtle hypermobility of the first tarsometatarsal joint can occur concomitantly with other pathologies and may be difficult to diagnose. Peroneus Longus muscle might influence stability of this joint. Collapse of the medial longitudinal arch is common in flatfoot deformity and the muscle might also play a role in correcting Meary's angle.

METHODS

A radiolucent frame was used to simulate weightbearing during CT examination. Eight pairs fresh-frozen lower legs were imaged in neutral position under non-weightbearing (75N), weightbearing (700N) and with 15kg weights hung from Peroneus Longus tendon. Measurements included first metatarsal rotation, intermetatarsal angle, first tarsometatarsal joint subluxation and Meary's angle.

FINDINGS

Weightbearing significantly increased Meary's angle and significantly decreased first tarsometatarsal joint subluxation (both P<0.01). Pulling Peroneus Longus tendon significantly increased first metatarsal rotation (P<0.01), significantly decreased the intermetatarsal angle (P<0.01) and increased non-significantly Meary's angle (P=0.52).

INTERPRETATION

A considerable effect weightbearing has on the medial longitudinal arch and first tarsometatarsal joint was observed. Pulling Peroneus Longus tendon improved first metatarsal subluxation but increased its rotation. The study calls into question the importance of this tendon in maintaining the medial longitudinal arch and raises concerns about rotational deformity of the first metatarsal following hallux valgus correction without first tarsometatarsal arthrodesis.

CLINICAL RELEVANCE

Study outcomes will provide more insight in foot pathology.

WHAT IS KNOWN ABOUT THE SUBJECT

Weightbearing affects anatomy of the foot. No reliable information is available concerning the influence of the Peroneus muscle.

WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE

This study investigates the influence of weightbearing and the impact the Peroneus muscle on the anatomy of the foot.

Proximal Intermetatarsal Divergence in Distal Chevron Osteotomy for Hallux Valgus: An Overlooked Finding

The goal of distal chevron osteotomy for hallux valgus is to restore proper first-toe joint alignment by performing lateral translation of the distal first metatarsal fragment (the metatarsal head). We hypothesized that in some patients this procedure might also result in involuntary medial translation of the proximal first metatarsal fragment, which we called proximal intermetatarsal divergence. The aim of the present study was to compare the pre- and postoperative radiographs of patients with hallux valgus to determine whether we could identify proximal intermetatarsal divergence. We retrospectively compared the pre- and postoperative radiographs of 29 feet in 28 patients treated with distal chevron osteotomy. Two different methods were used to measure the intermetatarsal angles: the anatomic intermetatarsal angle (aIMA) and the mechanical intermetatarsal angle (mIMA). The maximum intermetatarsal distance (MID) was also measured. We defined proximal intermetatarsal divergence as a postoperative increase in the aIMA or MID, coupled with a decrease in the mIMA. For data analysis, we divided the patients into low-angle (mild deformity) and high-angle (severe deformity) groups, according to their preoperative mIMA. The mean ± standard deviation patient age was 41 ± 14 years. In the low-angle group, the mean mIMA decreased (from 10.91° to 7.00°), the mean aIMA increased (from 11.80° to 13.55°), and the mean MID increased (from 17.97 mm to 20.60 mm; p = .001, for all). In the high-angle group, the mean mIMA decreased (from 14.30° to 6.90°; p = .001), the mean aIMA decreased (from 14.77° to 13.54°; p = .06), and the mean MID decreased (from 20.74 mm to 20.37 mm; p = .64). The results of our study suggest that proximal intermetatarsal divergence might occur after distal chevron osteotomy for hallux valgus, primarily in patients with a low preoperative mIMA.

Quantitative Analysis of the Degree of Frontal Rotation Required to Anatomically Align the First Metatarsal Phalangeal Joint During Modified Tarsal-Metatarsal Arthrodesis Without Capsular Balancing

The data from 35 consecutive patients with hallux valgus undergoing triplane arthrodesis at the first tarsal metatarsal joint were studied to determine the amount of first metatarsal frontal plane rotation (supination) needed to anatomically align the first metatarsal phalangeal joint on an anterior posterior radiograph without soft tissue balancing at the first metatarsal phalangeal joint. Radiographs were measured both pre- and postoperatively to assess the 1-2 intermetatarsal angle, hallux abductus angle, and tibial sesamoid position (TSP). The mean amount of varus (supination) rotation performed during correction was 22.1° ± 5.2° and the mean amount of intermetatarsal angle reduction achieved after completion of the procedure was 6.9° ± 3.0°. The TSP changed by a mean of 3.3° ± 1.2°. A series of univariate linear regression analyses was performed to analyze the relationship between the frontal plane rotation of the first metatarsal performed during the operation and the preoperative intermetatarsal angle, hallux abductus angle, and TSP. Greater preoperative TSP scores were associated with greater intraoperative varus (supination) rotation required for joint alignment. Direct observation of the alignment changes at the first metatarsal phalangeal joint after metatarsal rotation without distal procedures strengthened the notion that the frontal plane rotational position plays an important role in the bunion deformity.

A New Measure of Tibial Sesamoid Position in Hallux Valgus in Relation to the Coronal Rotation of the First Metatarsal in CT Scans

BACKGROUND

We aimed to find a new radiographic measurement for evaluating first metatarsal pronation and sesamoid position in hallux valgus (HV) deformity.

METHODS

Data from a clinical study of 19 control patients (19 feet) with no HV deformity were compared with preoperative data of 138 patients (166 feet) with HV deformities. Using a weightbearing plain radiograph in anteroposterior (AP) view, the intermetatarsal angles (IMAs) and the hallux valgus angles (HVAs) of the control and study groups were measured. Using a semi-weightbearing coronal computed tomography (CT) axial view, the α angle was measured in the control and study groups. In addition, the tibial sesamoid grades in plain radiograph tangential view and the CT axial view were measured. The tibial sesamoid position in an AP view was checked preoperatively. Based on these measurements, 4 types of HV deformities were defined.

RESULTS

The mean values of the α angle in the control and HV deformity groups (control group µ = 13.8 degrees, study group µ = 21.9 degrees) was significantly different. Among 166 HV feet, 145 feet (87.3%) had an α angle of more than 15.8 degrees, which is the upper value of the 95% confidence interval of the control group, indicating the existence of abnormal first metatarsal pronation in HV deformity. Four types of HV deformities were defined based on their α angles and tibial sesamoid grades in CT axial view (CT 4 position). Among 25.9% (43/166) of the study group, abnormal first metatarsal pronation with an absence of sesamoid deviation from its articular facet was observed. The prominent characteristic of this group was that they had high grades in the AP 7 position (≥5); however, in the CT 4 position, their grade was 0. This group was defined as the "pseudo-sesamoid subluxation" group.

CONCLUSIONS

Patients with HV deformities had a more pronated first metatarsal than the control group, with a greater α angle. Pseudo-subluxation of the sesamoids existed in 25.9% of our study group. From our results, we suggest that the use of the CT axial view in assessments of HV deformity may benefit surgeons when they make operative choices to correct these deformities. With regard to the pseudo-sesamoid subluxation group, the use of the distal soft tissue procedure is not surgically recommended.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Is our current paradigm for evaluation and management of the bunion deformity flawed? A discussion of procedure philosophy relative to anatomy

Of the >100 procedures that have been proposed to treat hallux valgus or the "bunion" deformity, most have focused on correction through metatarsal osteotomies at various levels combined with soft tissue balancing procedures at the first metatarsophalangeal joint. This paradigm of metatarsal osteotomy and soft tissue balancing has been so commonplace, any argument for a fundamental change to the approach becomes uncomfortable and seems unwarranted to most foot and ankle surgeons. However, the simple fact that so many procedures exist, with so many modifications of these procedures, can be interpreted as a failure of our basic paradigm of metatarsal osteotomy and soft tissue balancing. We have observed that failure to recognize frontal plane rotation of the first metatarsal and our willingness to ignore deformity correction principles and create osteotomies outside the center of rotation of angulation are factors that can result in inconsistent outcomes. Our current multiprocedural mindset drives the search for yet more procedures and modifications in an attempt to reduce the incidence of complications. We present an anatomic analysis of hallux abducto valgus and metatarsus primus adducto valgus and critically analyze some of the shortcomings of currently popular corrective procedures. We also review the available data regarding frontal plane rotation of the first metatarsal and propose a new paradigm that considers frontal plane rotation of the first metatarsal as a priority in choosing the most appropriate procedure for bunion correction.

Biodynamics of hallux abductovalgus etiology and preoperative evaluation

Hallux abductovalgus (HAV) is a common but complex deformity. HAV is a combination of deformities and abnormalities. Because HAV is not from a single cause or pathologic process, controversies in description and potential treatments exist. Although many HAV deformities appear similar, no two are the same and thus cannot be treated the same surgically.

Observed changes in radiographic measurements of the first ray after frontal and transverse plane rotation of the hallux: does the hallux drive the metatarsal in a bunion deformity?

It is well known that the pathologic positions of the hallux and the first metatarsal in a bunion deformity are multiplanar. It is not universally understood whether the pathologic changes in the hallux or first metatarsal drive the deformity. We have observed that frontal plane rotation of the hallux can result in concurrent positional changes proximally in the first metatarsal in hallux abducto valgus. In the present study, we observed the changes in common radiographic measurements used to evaluate a bunion deformity in 5 fresh frozen cadaveric limbs. We measured the tibial sesamoid position, 1-2 intermetatarsal angle, and first metatarsal cuneiform angle on anteroposterior radiographs after frontal and transverse plane manipulation of the hallux. When the hallux was moved into an abducted and valgus position, a statistically significant increase was found in the tibial sesamoid position (p = .016). However, we did not observe a significant increase in the intermetatarsal angle (p = .070) or medial cuneiform angle (p = .309). When the hallux was manipulated into an adducted and varus position, a statistically significant decrease in the intermetatarsal angle (p = .02) and a decrease in the tibial sesamoid position (p = .016) was seen, with no significant change in the medial cuneiform angle (p = .360). We also observed a consistent rounding of the lateral aspect of the first metatarsal head and an increase in the concavity of the lateral metatarsal shaft, with valgus rotation of the hallux. From these observations, it is possible that the hallux could drive the proximal changes in the first ray that lead to metatarsus primus adducto valgus deformity.