Tendon shift in hallux valgus: observations at MR imaging

Are sesamoids and proximal phalanx of metatarsus primus varus deformity of hallux valgus feet displaced? A radiological study

BACKGROUND

The hallux valgus deformity is made up of misaligned first metatarsal, hallux, and sesamoids. Their angular deformities are well-studied, but not their positional displacements. A few available reports claimed the proximal end of the proximal phalanx and sesamoids were not shifted medially along with the first metatarsal head. However, the general observation is otherwise. This study revisits the issue.

METHODS

A radiological study of 189 feet with and without the hallux valgus deformity was carried out to analyze the first metatarsal, hallux, and sesamoid positional changes in relation to the second metatarsal and among themselves. A total of 194 X-ray images with all relevant measurements that formed the raw database for this study were submitted for online viewing and reference.

RESULTS

There was a statistically significant change in the first metatarsal, hallux, and sesamoid positions of feet with hallux valgus deformity compared to normal feet. All have migrated medially but to different degrees. It was contrary to the past findings of no change in sesamoid and hallux positions.

CONCLUSIONS

We agree with past findings that the metatarsus primus varus deformity is directly related to the failed medial metatarsosesamoid ligament. We also believe in the failure of the deep 1-2 transverse metatarsal ligament responsible for the sesamoid migration.

Distribution, prevalence, and impact on the metatarsosesamoid complex of first metatarsal pronation in hallux valgus

BACKGROUND

Previous simulated weight-bearing CT (WBCT) studies classifying first metatarsal (M1) pronation suggested a high prevalence of M1 hyper-pronation in hallux valgus (HV). These findings have prompted a marked increase in M1 supination in HV surgical correction. No subsequent study confirms these M1 pronation values, and two recent WBCT investigations suggest lower normative M1 pronation values. The objectives of our WBCT study were to (1) determine M1 pronation distribution in HV, (2) define the hyperpronation prevalence compared to preexisting normative values, and (3) assess the relationship of M1 pronation to the metatarso-sesamoid complex. We hypothesized that the M1 head pronation distribution would be high in HV.

METHODS

We retrospectively identified 88 consecutive feet with HV in our WBCT dataset and measured M1 pronation with the Metatarsal Pronation (MPA) and α angles. Similarly, using two previously published methods defining the pathologic pronation threshold, we assessed our cohort's M1 hyper-pronation prevalence, specifically (1) the upper value of the 95% confidence interval (CI95) and (2) adding two standard deviations at the mean normative value (2 SD). Sesamoid station (grading) was assessed on the coronal plane.

RESULTS

The mean MPA was 11.4+/-7.4 degrees and the α angle was 16.2+/-7.4 degrees. According to the CI95 method, 69/88 HV (78.4%) were hyperpronated using the MPA, and 81/88 HV (92%) using the α angle. According to the 2 SD method, 17/88 HV (19.3%) were hyperpronated using the MPA, and 20/88 HV (22.7%) using the α angle. There was a significant difference in MPA among sesamoid gradings (p = 0.025), with a paradoxical decrease in MPA when metatarsosesamoid subluxation was increased.

CONCLUSION

M1 head pronation distribution in HV was higher than in normative values, but threshold change demonstrated contradictory hyper-pronation prevalences (85% to 20%), calling into question the previously reported high prevalence of M1 hyper-pronation in HV. An increase in sesamoid subluxation was associated with a paradoxical decrease in M1 head pronation in our study. We suggest that a greater understanding of the impact of HV M1 pronation is warranted before routine M1 surgical supination is recommended for patients with HV.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Positional and dimensional relation of tendons around the first metatarsal bone with hallux valgus

PURPOSE

It was aimed to reveal whether the positions and dimensions of the extrinsic and intrinsic muscle tendons related to the hallux around the first metatarsal bone are affected by the severity of hallux valgus (HV) and whether tendon positional changes and tendon sizes affect each other.

METHODS

In formalin-fixed 46 feet, three HV angle subgroups (normal, mild, and moderate/severe) were defined. Width, thickness, and cross-sectional area (CSA) of tendons of the extensor hallucis longus (EHL) and brevis (EHB), abductor hallucis (AH), and flexor hallucis longus (FHL) were measured. On the clock model created in coronal plane, positional variations of each tendon were determined.

RESULTS

In the moderate/severe HV group, thickness and CSA of the EHB, width and CSA of the AH were smaller, compared to mild HV. Width and CSA of the FHL were smaller in moderate/severe HV than in the normal. Regardless of HV, the width and CSA of the FHL were greater in cases where the FHL was located more lateral, and the width of both FHL and AT were greater in cases where AH located was more plantar.

CONCLUSION

The smaller tendon size of two intrinsic (one plantar and one dorsal) and one extrinsic muscle in the moderate/severe HV group indicates that changes in the tendons are evident in cases of high severity of HV but not in cases of mild HV. Accordingly, the changes do not appear to be due to a factor limited to only one aspect of the foot. It is recommended to consider the possible biomechanical effects of AH, FHL, and EHB tendon dimensional weakness in surgical planning in moderate/severe HV cases.

Intra- and Inter-rater Reliability of a Magnetic Resonance Imaging-Based Volumetric Analysis of the Abductor Hallucis Muscle

Background: The muscle volume considerably changes with aging, pathologies, mechanical loading and exercise, and immobilization. It is recognized as an important parameter that can be measured by various methods to evaluate the effectiveness of interventions focusing on muscle strengthening and function. However, before the application of any measurement method, their reliability needs to be investigated and established. Objectives: This study aimed to evaluate the inter- and intra-rater reliability of the manual measurement method of the abductor hallucis muscle volume in feet with hallux valgus deformities using magnetic resonance imaging (MRI). Patients and Methods: The MRI images of the feet of 15 samples with a hallux valgus deformity were selected in this study. The cross-sectional areas of the abductor hallucis muscle were measured in the cuts along the entire length of the foot and multiplied by slice thickness. Two trained raters performed the measurements. The second rater repeated the measurements after five days to eliminate the memory effect. The intra-rater reliability and inter-rater reliability were assessed based on the intraclass correlation coefficient [ICC (2, 1)] to evaluate the extent of agreement between the raters at a 95% confidence interval. Results: The between- and within-rater ICCs were 0.92 (0.79 - 0.97) and 0.99 (0.97 - 0.99), respectively. The standard error of measurements was also small in both inter-rater (6.2%) and intra-rater (2.1%) reliability analyses. Conclusion: The manually outlined slice-by-slice volume measurement of the abductor hallucis muscle based on MRI images showed excellent inter- and intra-rater reliability. The excellent intra-rater reliability, besides the lower standard error percentage of measurements, indicates the superiority of measurements by a single person. However, further studies with a larger sample size are recommended.

Impact of First Metatarsal Hyperpronation on First Ray Alignment: A Study in Cadavers

BACKGROUND

There is increased evidence of first metatarsal hyperpronation in patients with hallux valgus, but its impact on the stability of the first metatarsophalangeal and metatarsosesamoid joints is unknown. A previous biomechanical study showed that an increase in hallucal pronation might lead to medial soft tissue failure of the first metatarsophalangeal joint. Conversely, dynamic studies on hallux valgus have shown that the first tarsometatarsal joint moves in supination during weightbearing, and supination was associated with an increase in the intermetatarsal angle (IMA) and hallux valgus angle (HVA).

QUESTIONS/PURPOSES

(1) Does an increase in first metatarsal pronation cause an increase in hallucal pronation? (2) Can an intrinsic increase in first metatarsal pronation lead to first ray supination during weightbearing? (3) Can a combination of intrinsic first metatarsal hyperpronation and first metatarsophalangeal medial soft tissue failure increase supination of the first ray during weightbearing? (4) Is first ray supination during weightbearing associated with an increase in the IMA and HVA?

METHODS

Twelve transtibial, nonpaired cadaver specimens without deformities were used. Each specimen underwent six weightbearing CT scans under different conditions. The first three CT examinations were performed without any osteotomy of the first metatarsal. The first was a simulated nonweightbearing condition. The second was a simulated weightbearing condition. The third was a simulated weightbearing condition with medial soft tissue release. Subsequentially, a 30° pronation osteotomy of the first metatarsal was performed, and the same sequence of weightbearing CT images was obtained. On each weightbearing CT image, the HVA, IMA, sesamoid rotation angle, metatarsal pronation angle (MPA), metatarsosesamoid rotation angle, and hallucal pronation (HP) were measured. Motions were calculated based on the differential values of these angular measurements produced by the six different conditions (weightbearing, medial soft tissue release, 30° pronation osteotomy, and combinations of these conditions). We compared means using a t-test for normally distributed variables and the Mann-Whitney U test for nonnormally distributed variables. Correlations were assessed with Pearson product-moment correlation coefficients.

RESULTS

We found that 30° pronation osteotomy of the first metatarsal increased the MPA and HP by 28° ± 4° and 26° ± 6°, respectively, in the nonweightbearing condition. No differences between the increase in MPA and the increase in HP were noted (mean difference 2° [95% CI -1° to 5°]; p = 0.20). Therefore, an increase in first metatarsal pronation caused an increase in hallucal pronation. When a 30° pronation osteotomy of the first metatarsal was performed, the first ray motion during weightbearing went from pronation to supination (4° ± 2° in pronation without osteotomy versus 4° ± 2° in supination after the osteotomy, mean difference 8° [95% CI 6° to 9°]; p < 0.001). Therefore, an intrinsic increase in pronation of the first metatarsal led to a first ray supination motion during weightbearing. When a first metatarsophalangeal medial soft tissue release was performed in addition to the 30° osteotomy of the first metatarsal, the supination motion of the first ray increased (4° ± 2° without medial soft tissue release versus 11° ± 7° after the release, mean difference 8° [95% CI 3° to 12°]; p = 0.003). Therefore, a combination of intrinsic first metatarsal hyperpronation and first metatarsophalangeal medial soft tissue failure increased supination of the first ray during weightbearing. Regarding static angular measurements, the HVA and IMA were not correlated with the MPA (ρ = 0.20; p = 0.09 and ρ = 0.22; p = 0.07, respectively). Regarding motions, as the HVA and IMA increased from nonweightbearing to weightbearing the pronation decreased, with strong correlations (ρ = -0.82; p < 0.001 and ρ = -0.77; p < 0.001, respectively). Therefore, a first ray supination during weightbearing was associated with an increase in the HVA and IMA.

CONCLUSION

The combination of first metatarsal intrinsic hyperpronation and first metatarsophalangeal medial soft tissue failure led to a hallux valgus deformity in this cadaveric study. The static measurement of first metatarsal head pronation relative to the ground (MPA) did not reflect the real intrinsic pronation of the first ray, and foot and ankle specialists should be careful when interpreting these measurements. Hallux valgus is a dynamic condition, and the deformity could be more correlated with motions during weightbearing than with plain static measurements.

CLINICAL RELEVANCE

First ray supination compensating for first metatarsal intrinsic hyperpronation might be an important factor in the hallux valgus pathogenesis. Further in vivo studies involving nonweightbearing and weightbearing comparative assessments of hallux valgus and controls should be performed to confirm this pathomechanism.

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.

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.

The functional capacity and morphological characteristics of the intrinsic foot muscles in subjects with Hallux Valgus deformity: A systematic review

BACKGROUND

The intrinsic foot muscles are vital for maintaining normal foot function. This study was conducted to systematically review the literature on the functional capacity and morphological characteristics of the intrinsic foot muscles in subjects with Hallux Valgus (HV) deformity.

METHODS

A search was carried out in all available electronic databases, including Pub Med, Scopus, Embase and Web of Science, for identifying any relevant studies published from 1990 to October 2018.

RESULTS

Three studies had investigated intrinsic foot muscle size using ultrasound imaging; two had reported electromyography parameters and four had measured the muscle force capacity. The results of the present review suggested that the functional capacity and morphological characteristics of intrinsic foot muscles are different in subjects with HV compared to those without this deformity.

CONCLUSION

This review found scientific evidence on muscle performance impairment in the abductor hallucis and flexor hallucis brevis in subjects with HV deformity.

Immediate effect of neuromuscular electrical stimulation on the abductor hallucis muscle: A randomized controlled trial

Hallux valgus (HV) is a foot deformity with deviation of the greater toe and the first metatarsal. There is little evidence on training the abductor hallucis muscle (AbdH) to treat HV because of the difficulty in implementing the necessary interventions. Although neuromuscular electrical stimulation (NMES) has been used to induce voluntary exercise, there is currently no study on NMES for AbdH. We aimed to verify the immediate effect of NMES on the AbdH muscle function. For the NMES group (n = 15), electrical stimulation was applied for 20 min. In the sham group (n = 15), the stimulating device was set but not turned on. Electromyogram, HV angle (HVA) at rest and during abduction of the big toe, and strength of the AbdH were evaluated. Analysis of covariance was used to investigate differences within groups using the baseline as the covariate. NMES significantly improved the maximal voluntary isometric contractions (%MVIC), HVA at exercise, and muscle strength (%MVIC: p = .00, HVA exercise: p = .00, AbdH strength: p = .00). HVA at rest showed no change (p = .12). Application of NMES on the AbdH muscle immediately improved its activity output, muscle strength, and HVA during exercise.

Muscle Activity Detectors-Surface Electromyography in the Evaluation of Abductor Hallucis Muscle

Despite the high availability of surface electromyography (sEMG), it is not widely used for testing the effectiveness of exercises that activate intrinsic muscles of foot in people with hallux valgus. The aim of this study was to assess the effect of the toe-spread-out (TSO) exercise on the outcomes of sEMG recorded from the abductor hallucis muscle (AbdH). An additional objective was the assessment of nerve conduction in electroneurography. The study involved 21 patients with a diagnosed hallux valgus (research group A) and 20 people without the deformation (research group B) who performed a TSO exercise and were examined twice: before and after therapy. The statistical analysis showed significant differences in the third, most important phase of TSO. After the exercises, the frequency of motor units recruitment increased in both groups. There were no significant differences in electroneurography outcomes between the two examinations in both research groups. The TSO exercise helps in the better activation of the AbdH muscle and contributes to the recruitment of a larger number of motor units of this muscle. The TSO exercises did not cause changes in nerve conduction. The sEMG and ENG are good methods for assessing this exercise but a comprehensive assessment should include other tests as well.

Hallux valgus assessment on X-ray and Magnetic resonance Imaging (MRI): Correlation with qualitative soft tissue and internal derangement findings on MRI

AIM

Radiographs (X-rays) are used for the preoperative assessment of hallux valgus (HV). Our purpose was to determine how well quantitative measurements of HV on radiographs and MRI correlate with the qualitative soft tissue and internal derangement findings on MRI.

MATERIALS AND METHODS

After IRB approval, 56 consecutive patients with MRI and radiographs of the foot were retrospectively reviewed. Two trained readers independently evaluated radiographs, measuring hallux valgus angle (HVA) and intermetatarsal angle (IMA). Two separate readers assessed qualitative MRI data by evaluating 21 different soft tissue and bony features. Statistical analysis included inter-reader reliability (IRR) and correlation of quantitative and qualitative findings.

RESULTS

Excellent IRR (ICC = 0.89-0.96) was observed for radiograph and MRI measurements of the hallux valgus severity. For qualitative assessments on MRI, IRR was good to excellent for all features (ICC = 0.63-0.9). No significant difference was found for HVA or IMA between normal and abnormal qualitative MRI features. No statistically significant correlation between the severity of hallux valgus and injury to hallux joints and supporting structures was found.

CONCLUSION

Hallux valgus measurements are reliable on x-rays and MRI and qualitative findings of 1st MTP joint show good to excellent inter-reader agreement on MRI. No statistically significant correlations exist between the severity of hallux valgus and qualitative MRI findings.

How I Use a Three-Dimensional Approach to Correct Hallux Valgus with a Distal Metatarsal Osteotomy

The role of uniplanar osteotomy in correction of multiplanar deformity in hallux valgus is a developing and promising concept. Careful consideration should be given to the literature when considering the concept of preexisting pronation of the metatarsal. Recent weight-bearing computed tomography studies contradict the existing literature and state that there is little or no rotation of the metatarsal; therefore, a multiplanar osteotomy should aim to correct the rotation caused by soft tissue imbalance at the tarsometatarsal and metatarsophalangeal joints rather than in the metatarsal itself. A minimally invasive technique used by the senior author to achieve this correction is reported.

Imaging of Hallux Valgus: How to Approach the Deformity

This article describes the pathogenesis of hallux valgus (HV) and the traditional ways to image the deformities. It also discusses up-to-date advances and research in the field of imaging in HV. This includes weight-bearing computed tomography (CT) scanning, MRI, ultrasound and intraoperative imaging.

The study of surface electromyography used for the assessment of abductor hallucis muscle activity in patients with hallux valgus

BACKGROUND

Hallux valgus is a common foot disorder. In patients with hallux valgus, the anatomy and biomechanics of foot is subject to alterations.

OBJECTIVE

The aim of this clinical and neurophysiological study is to compare the activity of abductor hallucis (AbdH) muscle between the group of patients with hallux valgus and control group of healthy people, with the use of surface electromyography.

METHODS

The study involved 44 feet with diagnosed hallux valgus (research group) and 42 feet without deformation (control group). The X-ray images, measurements of range of motion in the first metatarsophalangeal joint and in hallux interphalangeal joint, and the surface electromyography study recorded from AbdH muscle were performed.

RESULTS

Considering the amplitude of motor unit action potential, study participants with hallux valgus demonstrate significantly less activity of AbdH muscle than people without hallux valgus deformity. This activity is not dependent on the severity of valgus, age, or range of motion.

CONCLUSIONS

It is speculated that the changes of the AbdH function may occur in the period before clinical appearance of hallux valgus deformity, or at the onset of distortion development. Further studies are needed for a comprehensive assessment of AbdH muscle in patients with hallux valgus.

[Soft tissue techniques in hallux valgus surgery]

The hallux valgus represents combined bony and soft tissue pathology. In addition to known bony surgical procedures, addressing the soft tissue with regard to the anatomical structures, the surgical technique and the extent of correction are discussed.The goal of the operation is the restoration of the physiological balance between the active and passive stabilizing factors of the MTP-I-joint. The joint capsule, the ligaments and the tendons of the first ray act directly as stabilizing structures, whereas the hind foot and the position of the upper ankle have an indirect influence on the MTP-I-joint.The present work gives an overview of the pathoanatomy of the MTP-I-joint in the hallux valgus pathology. The individual anatomical structures are presented with regard to their physiological and pathological influence and the possible therapeutic options.

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.

The effect of age on muscle characteristics of the abductor hallucis in people with hallux valgus: a cross-sectional observational study

Background

The abductor hallucis muscle plays an important role in maintaining alignment of the first metatarsophalangeal joint. The aims of this study were (1) to determine differences in abductor hallucis muscle characteristics in people with hallux valgus between three age groups (20–44 years, 45–64 years, and 65+ years); and (2) to determine the association between age and abductor hallucis size and quality.

Methods

Characteristics of the abductor hallucis muscle were measured in 96 feet with hallux valgus using musculoskeletal ultrasound. Muscle characteristics included width, thickness, cross-sectional area and echo-intensity. A one-way ANCOVA was conducted to compare the mean muscle characteristic values between the three age groups while adjusting for hallux valgus severity as a covariate. A Bonferroni post-hoc was used to adjust for multiple testing (p < 0.0167). Spearman’s rho correlation coefficient was used to determine the association between age and the abductor hallucis muscle parameters.

Results

There was a significant difference in dorso-plantar thickness (p = 0.003) and cross-sectional area (p = 0.008) between the three age groups. The Bonferroni post hoc analysis revealed a significant difference in mean thickness and mean cross-sectional area between the 20–44 age group (p = 0.003) and the 65+ age group (p = 0.006). No significant differences were noted between the three age groups for medio-lateral width (p > 0.05) or echo-intensity (p > 0.05). Increasing age was significantly associated with a reduction in dorso-plantar thickness (r = −0.27, p = 0.008) and cross-sectional area (r = −0.24, p = 0.019) but with small effect sizes. There was no significant correlation between age and medio-lateral width (r = −0.51, p = 0.142) or echo intensity (r =0.138, p =0.179).

Conclusion

Increasing age is associated with a greater reduction in size of the abductor hallucis muscle in people with hallux valgus. People over the age of 65 years old with hallux valgus display a significant reduction in abductor hallucis muscle size compared to those aged less than 45 years old. This is consistent with age-related changes to skeletal muscle.

Scarf osteotomy

The term scarf osteotomy was first used by Weil when presenting his results from more than 1000 cases. Scarf is a carpentry term describing beveling the ends of 2 pieces of wood and securely fastening them so that they overlap to create one continuous piece. This technique was popularized by Weil and Barouk as a versatile method of correcting hallux valgus while maintaining the blood supply to the metatarsal head. It also has rigid fixation, allowing early mobilization. This article addresses the surgical technique of the scarf osteotomy together with the results and complications of hallux valgus correction.

Ultrasonic evaluation of the abductor hallucis muscle in hallux valgus: a cross-sectional observational study

BACKGROUND

The aim of the study was to investigate the abductor hallucis muscle characteristics, defined as dorso-plantar (DP) thickness, medio-lateral (ML) width, and cross-sectional area (CSA) in relation to the severity of hallux valgus using musculoskeletal ultrasound. One hundred and two feet, mean (SD) age of 60.3 (20.54) years old, displaying varying severities of hallux valgus were stratified into four groups representing the four grades of the Manchester Scale (grade 0: no deformity, grade 1: mild deformity, grade 2: moderate deformity and grade 3: severe deformity).

METHODS

The abductor hallucis muscle was imaged in each foot using a portable ultrasound system. The mean (SD) DP thickness, ML width, and CSA measurements were compared across the four Manchester Scale grades using a one-way ANOVA.

RESULTS

Significant differences in DP thickness were found between feet with no hallux valgus (grade 0) and feet with hallux valgus grade 2 (p=0.001) and 3 (p<0.001). Significant differences were also found in ML width between feet with no hallux valgus (grade 0) and feet with grade 2 hallux valgus (p=0.010). Significant differences in CSA were found between feet with no hallux valgus (grade 0) and feet with grade 2 (p<0.001) and grade 3 (p<0.001) hallux valgus. No significant differences in these three muscle characteristics were found between grades 1, 2 and 3 (p>0.0125).

CONCLUSIONS

We speculate that morphological changes to the abductor hallucis muscle occur early in the development of the deformity.

Characteristics of foot structure and footwear associated with hallux valgus: a systematic review

OBJECTIVE

Factors associated with the development of hallux valgus (HV) are multifactorial and remain unclear. The objective of this systematic review and meta-analysis was to investigate characteristics of foot structure and footwear associated with HV.

DESIGN

Electronic databases (Medline, Embase, and CINAHL) were searched to December 2010. Cross-sectional studies with a valid definition of HV and a non-HV comparison group were included. Two independent investigators quality rated all included papers. Effect sizes and 95% confidence intervals (CIs) were calculated (standardized mean differences (SMDs) for continuous data and risk ratios (RRs) for dichotomous data). Where studies were homogeneous, pooling of SMDs was conducted using random effects models.

RESULTS

A total of 37 papers (34 unique studies) were quality rated. After exclusion of studies without reported measurement reliability for associated factors, data were extracted and analysed from 16 studies reporting results for 45 different factors. Significant factors included: greater first intermetatarsal angle (pooled SMD = 1.5, CI: 0.88-2.1), longer first metatarsal (pooled SMD = 1.0, CI: 0.48-1.6), round first metatarsal head (RR: 3.1-5.4), and lateral sesamoid displacement (RR: 5.1-5.5). Results for clinical factors (e.g., first ray mobility, pes planus, footwear) were less conclusive regarding their association with HV.

CONCLUSIONS

Although conclusions regarding causality cannot be made from cross-sectional studies, this systematic review highlights important factors to monitor in HV assessment and management. Further studies with rigorous methodology are warranted to investigate clinical factors associated with HV.

Multisegmental foot and ankle motion analysis after hallux valgus surgery

BACKGROUND

Gait changes in patients with hallux valgus, including altered kinematic and temporal-spatial parameters, have been documented in the literature. Although operative treatment can yield favorable clinical and radiographic results, restoration of normal gait in this population remains unclear. Segmental kinematic changes within the foot and ankle during ambulation after operative correction of hallux valgus have not been reported. The aim of this study was to analyze changes in multisegmental foot and ankle kinematics in patients who underwent operative correction of hallux valgus.

METHODS

A 15-camera Vicon Motion Analysis System was used to evaluate 24 feet in 19 patients with hallux valgus preoperatively and postoperatively. The Milwaukee Foot Model was used to characterize segmental kinematics and temporal-spatial parameters (TSPs). Preoperative and postoperative kinematics and TSPs were compared using paired nonparametric methods; comparisons with normative data were performed using unpaired nonparametric methods. Outcomes were evaluated using the SF-36 assessment tool.

RESULTS

Preoperatively, patients with hallux valgus showed significantly altered temporal-spatial and kinematic parameters. Postoperatively, kinematic analysis demonstrated restoration of hallux position to normal. Hallux valgus angles and intermetatarsal angles were significantly improved, and outcomes showed a significant increase in performance of physical activities. Temporal-spatial parameters and kinematics in the more proximal segments were not significantly changed postoperatively.

CONCLUSION

Postoperative results demonstrated significant improvement in foot geometry and hallux kinematics in the coronal and transverse planes. However, the analysis did not identify restoration of proximal kinematics.

CLINICAL RELEVANCE

Further investigation is necessary to explore possible causes/clinical relevance and appropriate treatment interventions for the persistently altered kinematics.

The pathogenesis of hallux valgus

The first ray is an inherently unstable axial array that relies on a fine balance between its static (capsule, ligaments, and plantar fascia) and dynamic stabilizers (peroneus longus and small muscles of the foot) to maintain its alignment. In some feet, there is a genetic predisposition for a nonlinear osseous alignment or a laxity of the static stabilizers that disrupts this muscle balance. Poor footwear plays an important role in accelerating the process, but occupation and excessive walking and weight-bearing are unlikely to be notable factors. Many inherent or acquired biomechanical abnormalities are identified in feet with hallux valgus. However, these associations are incomplete and nonlinear. In any patient, a number of factors have come together to cause the hallux valgus. Once this complex pathogenesis is unraveled, a more scientific approach to hallux valgus management will be possible, thereby enabling treatment (conservative or surgical) to be tailored to the individual.

[A special soft tissue procedure for treatment of hallux valgus]

OBJECTIVE

Maintaining the corrected position of the first metatasophalangeal axis. Reducing postoperative stiffness by forgoing a medial capsular shift.

INDICATIONS

Hallux valgus deformities or recurrent hallux valgus deformities.

CONTRAINDICATIONS

Existing osteoarthritis, joint stiffness, large bone defects, osteonecrosis. General medical contraindications to surgical interventions and anesthesiological procedures.

SURGICAL TECHNIQUE

Operation under regional anesthesia (foot block) or general anesthesia. Tourniquet. Longitudinal skin incision medial over the pseudexostosis of the first metatarsal bone. Preparing the tendon of the Musculus abductor hallucis. Detaching the tendon from the capsule. Incision of the joint capsule with protection of the extensor hallucis longus tendon and the dorsal neurovascular bundle in an L-wise manner. Osteotomy of the first metatarsal bone. Lax sutures of the capsule in correct position and reattachment of the Musculus abductor hallucis tendon shifted toward distal and dorsal, regarding the rotation of the hallux.

POSTOPERATIVE MANAGEMENT

Postoperative elevation of the operated foot. Analgesia with nonsteroidal antiinflammatory drugs. Postoperative weight-bearing according to the osteotomy. Passive mobilization of the metatarsophalangeal joint. Dressing for 4 weeks postoperatively in the corrected position. Radiologic control after 6 weeks. Hallux valgus orthosis at night and a toe spreader for a further 6 weeks.

RESULTS

A total of 30 isolated hallux valgus deformities with a mean preoperative intermetatarsal (IMA) angle of 12.9° (range 11-15°) were operated with a chevron osteotomy. The mean follow-up was 14.4 (range 8-17) months. The mean dorsiflexion at the last follow-up was 44° (range 20-60°). Only 2 patients had a dorsiflexion <40°. The mean reduction of the IM angle was 5.6° (range 3-7°). One patient required wound revision. There was no infection or avascular necrosis of the metatarsal head observed in the patients. At follow-up, 20 (67%) patients were completely satisfied, 9 (30%) satisfied, and 1 (3%) was not satisfied.

Ultrasound evaluation of the abductor hallucis muscle: Reliability study

Background

The Abductor hallucis muscle (AbdH) plays an integral role during gait and is often affected in pathological foot conditions. The aim of this study was to evaluate the within and between-session intra-tester reliability using diagnostic ultrasound of the dorso-plantar thickness, medio-lateral width and cross-sectional area, of the AbdH in asymptomatic adults.

Methods

The AbdH muscles of thirty asymptomatic subjects were imaged and then measured using a Philips HD11 Ultrasound machine. Interclass correlation coefficients (ICC) with 95% confidence intervals (CI) were used to calculate both within and between session intra-tester reliability.

Results

The within-session reliability results demonstrated for dorso-plantar thickness an ICC of 0.97 (95% CI: 0.99–0.99); medio-lateral width an ICC: of 0.97 (95% CI: 0.92–0.97) and cross-sectional area an ICC of 0.98 (95% CI: 0.98–0.99). Between-session reliability results demonstrated for dorso-plantar thickness an ICC of 0.97 (95% CI: 0.95 to 0.98); medio-lateral width an ICC of 0.94 (95% CI 0.90 to 0.96) and for cross-sectional area an ICC of 0.79 (95% CI 0.65 to 0.88).

Conclusion

Diagnostic ultrasound has the potential to be a reliable tool for evaluating the AbdH muscle in asymptomatic subjects. Subsequent studies may be conducted to provide a better understanding of the AbdH function in foot and ankle pathologies.

Insertion of the tendon of the tibialis anterior muscle in feet with and without hallux valgus

The insertion of the tendon of the tibialis anterior muscle may be related to pathologic changes of the foot and, in particular, hallux valgus. Morphologic data should enable evaluation of such a relationship and perhaps offer a basis for improved therapy. One hundred fifty-six embalmed feet, including 27 with hallux valgus, were examined. The tendon of the tibialis anterior muscle was dissected and measurements were made, including the width of the insertion on the first metatarsal and medial cuneiform. Distal-superficial and proximal-deep slips of the tendon twisted around each other. Two specimens presented with an insertion only on the medial cuneiform; in two other cases the insertion was limited to the first metatarsal; in one case the tendon inserted into the navicular and the medial cuneiform; in all other cases, the tendon inserted into the medial cuneiform and first metatarsal. The insertion was mainly located along the plantar margin of the medial side of the foot; some of the proximal-deep fibers also passed onto the plantar surface. Fibers inserting on the first metatarsal bone can outwardly rotate the first ray, which is opposite to the inward rotation of the first ray in hallux valgus. In all feet with hallux valgus these fibers were present. Therefore, it is unlikely that this deformity develops because of a specific type of insertion of the tendon of the tibialis anterior muscle, and any therapeutic approach altering the attachment of the tibialis anterior tendon would cause no biomechanical improvement.

Hallux valgus and hallux rigidus: MRI findings

The purpose of this article is to describe the MR findings of Hallux Valgus (HV) and Hallux Rigidus (HR). Twenty-four patients (11 with HV, 4 with HR, and 9 with both HV and HR) were studied at 1.5 Tesla MRI. Two separate observers evaluated the first ray blindly for the following signs: sesamoid position, sesamoid proliferation, hypertrophy of the median eminence, presence of a lateral facet, presence of an adventitial bursa, shape of the first metatarsal head, relative length of the first metatarsal, joint space loss, osteophytes (dorsalor lateral), marrow edema, geodes, subchondral sclerosis, intra-articular ossicle, and pes planus. The most common findings observed in HV were a hypertrophic medial eminence (95%), sesamoid proliferation (90%) and adventitial bursitis (70%). The most common findings observed in HR were osteophytes (77% and 69%), geodes, and marrow edema. We conclude that traditional routine radiograph signs of HV and HR may be applied to MR images.

Insertion of the abductor hallucis muscle in feet with and without hallux valgus

Textbooks of human anatomy present different opinions on the insertion of the abductor hallucis muscle which is concerned in etiology as well as in therapy of hallux valgus. In plastic and reconstructive surgery the muscle is taken as a graft for flap-surgery. In this study 109 feet (58 right, 51 left) were examined, 18 of these with clinical hallux valgus. The tendon of the muscle may attach to the tendon of the medial head of the short flexor hallucis muscle where a subtendineous bursa can be found. At the head of the first metatarsal bone the joint capsule is reinforced by fibres arising from the medial sesamoid bone which may be called "medial sesamoidal ligament." The tendon passes the first metatarsophalangeal joint plantarily to its transverse axis. Three types of insertion could be distinguished: type A, insertion at the proximal phalanx (N = 42); type B, insertion at the medial sesamoid ligament and at the medial sesamoid bone (N = 65); type C, insertion at the medial sesamoid bone (N = 2). In all types superficial fibres of the tendon extended to the medial and plantar sides of the base of the proximal phalanx, running in a plantar to dorsal direction. Statistical analysis exposed neither significant differences between both sides nor significant difference between normal feet and feet with hallux valgus. Therefore, a specific pattern of insertion of the abductor hallucis muscle in hallux valgus cannot be stated.