Coronal Plane Rotation of the Medial Column in Hallux Valgus: A Retrospective Case-Control Study

BACKGROUND

We previously reported an increase in pronation of the first metatarsal (M1) head relative to the ground in hallux valgus (HV) patients compared to controls. Still, the origin and location of this hyperpronation along the medial column is unknown. Recent studies showed that presence of progressive collapsing foot deformities (PCFDs), which is a condition frequently associated with HV, can strongly influence the medial column coronal plane alignment. The objective of this study was to assess the coronal rotation of the medial column bones in HV feet, HV feet with radiologic markers of PCFD, and controls. We hypothesized that hyperpronation in HV will originate from a combination of M1 intrinsic torsion and first tarsometatarsal joint malposition.

METHODS

The same cohort of 36 HV and 20 controls matched on age, gender, and body mass index was used. Previously, a validation of the measurements was carried out through a cadaveric study. Using these metrics, we assessed the coronal plane rotation of the navicular, medial cuneiform, and the M1 at its base and head with respect to the ground using weightbearing CT images. We measured the Meary angle and the calcaneal moment arm in our 36 HV subjects. We subdivided our cohort into an HV group and a potential PCFD HV group according to these measurements. Comparisons on medial column bones coronal rotation were performed between HV, PCFD HV, and control groups.

RESULTS

Twenty-two HV cases were included in the HV group and 14 in the PCFD HV group. Both groups presented an increase in pronation of the first metatarsal head relative to the ground when compared to the control group (P < .001). Comparing HV and controls showed an 8.3 degrees increase in pronation of M1 intrinsic torsion (P < .001) and a 4.7 degrees pronated malposition of the first tarsometatarsal joint (P = .02) in HV. A 9.7 degrees supinated malposition of the first naviculocuneiform joint (P < .001) was also observed in HV. Comparing PCFD HV and controls showed a significant increase in pronation of the navicular (respectively, 17.2 ± 5.4 and 12.3 ± 3.4 degrees, P = .007) and a 5.5 degrees increase in pronation of M1 intrinsic torsion (P = .02) in PCFD HV, without malposition of the first tarsometatarsal and naviculocuneiform joints.

CONCLUSION

Hyperpronation of the M1 head relative to the ground originated from both increases in pronation of M1 intrinsic torsion and first tarsometatarsal joint malposition in HV, although partially counterbalanced by a supinated malposition of the first naviculocuneiform joint. On the other hand, PCFD HV patients showed a generalized pronated position throughout the medial column from the navicular to the M1 head and may be related to the midfoot and hindfoot deformities frequently present in PCFD.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Should Diastatic Syndesmosis be Stabilized in Advanced Pronation-External Rotation Ankle Injuries? A Retrospective Cohort Comparison

OBJECTIVE

With or without screw stabilization for diastatic syndesmosis in advanced pronation-external rotation (PE) ankle injuries has not yet been well-determined. Both techniques were retrospectively compared to investigate the superiority of either of the two.

METHODS

A retrospective cohort study was carried out. From January 1, 2008, to December 31, 2017, 81 consecutive adult patients (average, 42 years; range, 18-78 years; 44 men and 37 women) with advanced PE ankle injuries (stage 3 or 4 PE type) were treated. After malleolar fractures were internally stabilized with screws and plates, the syndesmotic stability was rechecked by external rotation and hook tests. The necessity of cortical screw insertion to stabilize diastatic syndesmosis was decided by the individual orthopaedic surgeon. Postoperatively, a short leg splint was used for 6 weeks. The syndesmotic screw was removed based on the surgeon's policy. The removal of internal fixation for malleolar fractures was required after 1 year. The outcomes of both approaches were compared clinically, and ankle function was compared using the American Orthopaedic Foot and Ankle Society (AOFAS) score. For statistical comparison, the chi-square test was used for categorical data and the Mann-Whitney U test was used for numerical data.

RESULTS

Seventy-one patients (average, 40 years; range, 18-78 years; 40 men and 31 women) were followed for at least 1 year (87.7%; average, 2 years; range, 1-11 years). Group 1 (with syndesmotic stabilization) had 22 patients and Group 2 (without syndesmotic stabilization), 49 patients. The union rate in Group 1 patients was 100% (22/22), and in Group 2 patients, 91.8% (45/49; p = 0.17). One deep wound infection occurred in Group 1 patients and two in Group 2 patients. Syndesmosis re-diastasis occurred in 13.6% (3/22) of Group 1 patients and 30.6% (15/49) of Group 2 patients (p = 0.13). One syndesmotic screw broke at 6 months. Satisfactory ankle function according to the AOFAS score was noted in 86.4% (19/22) of Group 1 patients and 65.3% (32/49) of Group 2 patients (p = 0.07).

CONCLUSION

Insertion of syndesmotic screws to promote ligament healing after internal fixation of malleolar fractures in advanced PE ankle injuries may be reasonable.

Side-to-Side Difference of Metatarsal Rotation in Normal Individuals

BACKGROUND

A previous study defined the normal first metatarsal pronation angle (MPA) as <16 degrees and normal α angle as <18 degrees. The primary purpose of this study was to assess the side-to-side variation in first metatarsal pronation between feet in normal individuals.

METHODS

MPA and α angles were measured on standardized coronal weightbearing computed tomography slices. Pairedt tests were used to test significance of mean side-to-side differences in a population of 63 normal, asymptomatic individuals.

RESULTS

The mean side-to-side difference in first metatarsal pronation was 4.3 degrees (95% CI 3.3, 5.2 degrees) for MPA and 4.9 degrees (95% CI 3.8, 6.0 degrees) for α angle. The normative range for side-to-side difference was calculated as 12 degrees for MPA and 14 degrees for α angle, as defined by 2 SDs from the mean.

CONCLUSION

In a cohort of normal patients, the mean difference in first metatarsal pronation between sides was approximately 4 to 5 degrees based on MPA and α angle. However, considerable variation in differences was observed. These findings may be considered when assessing first metatarsal pronation using population-based values as it may influence thresholds for identifying pathology in an individual.

Imaging Findings and First Metatarsal Rotation in Hallux Valgus

BACKGROUND

Failure to identify and correct malrotation of the first metatarsal may lead to recurrent hallux valgus deformity. We aimed to identify the proportion of hallux valgus patients with increased first metatarsal pronation using weightbearing computed tomography (WBCT) and to identify the relationship with conventional radiographic measurements.

METHODS

WBCT scans were analyzed for 102 feet with a hallux valgus angle (HVA) and intermetatarsal angle (IMA) greater than or equal to 16 and 9 degrees, respectively. Metatarsal pronation angle (MPA), alpha angle, sesamoid rotation angle (SRA), and sesamoid position were measured on standardized coronal WBCT slices. Pronation was recorded as positive. Hindfoot alignment angle (HAA) was assessed using dedicated software. Pearson correlation and multiple regression analyses were used to assess differences between groups.

RESULTS

Mean HVA was 29.8±9.4 degrees and mean IMA was 14.1±3.7 degrees. Mean MPA was 11.9±5.8 (range 0-26) degrees and mean alpha angle was 11.9±6.8 (range -3 to 29) degrees. In a previous study, we demonstrated the upper limit of normal MPA as 16 degrees and alpha angle as 18 degrees. Based on these criteria, we identified abnormal metatarsal pronation in 32 feet (31.4%). We found a strong positive correlation between SRA and HVA/IMA (R = 0.67/0.60, respectively, P < .001). IMA and HAA weakly correlated with MPA and alpha angle (IMA: R = 0.26/0.27, respectively, P < .01; HAA: R = 0.26/0.27, respectively, P < .01). Regression analyses suggested that increasing IMA was the most significant radiographic predictor of increased pronation. In this cohort, there was no correlation between HVA or sesamoid position and MPA / alpha angle (HVA: P = .36/.12, respectively, sesamoid position, P = .86/.77, respectively).

CONCLUSION

In this cohort of 102 feet that met plain radiographic criteria for hallux valgus deformity, first metatarsal pronation was found abnormal in 31.4% of patients. We found a weak association between the IMA and hindfoot valgus, but not the HVA.

Distal Metatarsal Articular Angle in Hallux Valgus Deformity. Fact or Fiction? A 3-Dimensional Weightbearing CT Assessment

BACKGROUND

The Distal Metatarsal Articular Angle (DMAA) was previously described as an increase in valgus deformity of the distal articular surface of the first metatarsal (M1) in hallux valgus (HV). Several studies have reported poor reliability of this measurement. Some authors have even called into question its existence and consider it to be the consequence of M1 pronation resulting in projection of the round-shaped lateral edge of M1 head.Our study aimed to compare the DMAA in HV and control populations, before and after computer correction of M1 pronation and plantarflexion with a dedicated weightbearing CT (WBCT) software. We hypothesized that after computerized correction, DMAA will not be increased in HV compared to controls.

METHODS

We performed a retrospective case-control study including 36 HV and 20 control feet. In both groups, DMAA was measured as initially described on conventional radiographs (XR-DMAA) and WBCT by measuring the angle between the distal articular surface and the longitudinal axis of M1. Then, the DMAA was measured after computerized correction of M1 plantarflexion and coronal plane rotation using the α angle (3d-DMAA).

RESULTS

The XR-DMAA and the 3d-DMAA showed higher significant mean values in HV group compared to controls (respectively 25.9 ± 7.3 vs 7.6 ± 4.2 degrees, P < .001, and 11.9 ± 4.9 vs 3.3 ± 2.9 degrees, P < .001).Comparing a small subset of precorrected juvenile HV (n=8) and nonjuvenile HV (n=28) demonstrated no significant difference in the measure DMAA values. On the other hand, the α angle was significantly higher in the juvenile HV group (21.6 ± 9.9 and 11.4 ± 3.7 degrees; P = .0046).

CONCLUSION

Although the valgus deformity of M1 distal articular surface in HV is overestimated on conventional radiographs, comparing to controls showed that an 8.6 degrees increase remained after confounding factors' correction.

CLINICAL RELEVANCE

After pronation computerized correction, an increase in valgus of M1 distal articular surface was still present in HV compared to controls.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Association of First Metatarsal Pronation Correction With Patient-Reported Outcomes and Recurrence Rates in Hallux Valgus

BACKGROUND

The purpose of this study was to determine if a postoperative decrease in first metatarsal pronation on 3-dimensional imaging was associated with changes in patient-reported outcomes as measured by the Patient-Reported Outcomes Measurement Information System (PROMIS) physical function, pain interference, and pain intensity domains or recurrence rates in patients with hallux valgus (HV) who undergo a first tarsometatarsal fusion (modified Lapidus procedure).

METHODS

Thirty-nine consecutive HV patients who met the inclusion criteria and underwent a modified Lapidus procedure had preoperative and ≥2-year postoperative PROMIS scores and had first metatarsal pronation measured on preoperative and at least 5-month postoperative weightbearing CT scans were included. Multivariable regression analyses were used to investigate differences in the change in PROMIS domains preoperatively and 2 years postoperatively between patients with "no change/increased first metatarsal pronation" and "decreased first metatarsal pronation." A log-binomial regression analysis was performed to identify if a decrease in first metatarsal pronation was associated with recurrence of the HV deformity.

RESULTS

The decreased first metatarsal pronation group had a significantly greater improvement in the PROMIS physical function scale by 7.2 points (P = .007) compared with the no change/increased first metatarsal pronation group. Recurrence rates were significantly lower in the decreased first metatarsal pronation group when compared to the no change/increased first metatarsal pronation group (risk ratio 0.25, P = .025).

CONCLUSION

Detailed review of this limited cohort of patients who underwent a modified Lapidus procedure suggests that the rotational component of the HV deformity may play an important role in outcomes and recurrence rates following the modified Lapidus procedure.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Repeatability of Weightbearing Computed Tomography Measurement of First Metatarsal Alignment and Rotation

BACKGROUND

Weightbearing computed tomography (WBCT) can be used to assess alignment and rotation of the first metatarsal. It is unknown whether these measures remain consistent on sequential WBCTs in the same patient when a patient's standing position may be different. The aim of this study was to establish the repeatability (test-retest) of measurements of first metatarsal alignment and rotation in patients without forefoot pathology on WBCT.

METHODS

We retrospectively identified 42 feet in 26 patients with sequential WBCT studies less than 12 months apart. Patients with surgery between scans, previous forefoot surgery or hallux rigidus were excluded. Hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured using digitally reconstructed radiographs. Two methods of calculating metatarsal rotation (metatarsal pronation angle [MPA] and alpha angle) were measured on standardized coronal CT slices. Interobserver agreement and test-retest repeatability were assessed using intraclass correlation coefficients (ICCs). Standard error of measurement (SEM) and minimally detectable change (MDC95) were calculated.

RESULTS

Interobserver agreement was excellent for HVA and IMA (ICC 0.96 and 0.90, respectively) and was good for MPA and alpha angle (ICC 0.81 and 0.80, respectively). There was excellent test-retest repeatability for HVA (ICC=0.90) and good test-retest repeatability for IMA (ICC=0.77). There was excellent test-retest repeatability for MPA (ICC=0.91) and good test-retest repeatability for alpha angle (ICC=0.87). The MDC95 was 4.6 degrees for MPA and 6.1 degrees for alpha angle. Five percent of patients had a difference outside of the MDC95 for the alpha angle, compared with 2% for the MPA.

CONCLUSION

Measurements of first metatarsal alignment and rotation are reliable between assessors and repeatable between sequential WBCTs in patients without forefoot pathology. Subtle differences in patient positioning during image acquisition do not significantly affect measurements, supporting the validity of this method of assessment in longitudinal patient care.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

The Effect of Forearm Shortening on Forearm Range of Motion

PURPOSE

Osseous shortening of the forearm is performed during forearm replantation; however, no large clinical reviews have discussed its effects on patient outcomes. A recent cadaver study demonstrated the progressive loss of forearm pronation/supination ranges of motion with increased shortening lengths using external fixation. Our study aimed to quantify the effects of shortening on passive forearm motion using internal fixation after 2, 4, and 6 cm of mid-forearm shortening.

METHODS

A volar Henry approach and direct approach to the ulna were used on 8 cadaveric specimens. The forearms were sequentially shortened by 2, 4, and 6 cm. Fixation was performed on the volar surfaces of the radius and ulna. Pronation and supination of the forearms were tested by applying 1 Nm of torque at baseline and after the fixation of both the radius and ulna using osteotomy. Radiographs and measurements were obtained at each phase to determine the maximum radial bow and radioulnar gap. Data were analyzed using a linear mixed-effects model.

RESULTS

Greater shortening of the radius and ulna led to progressively greater reductions in both pronation and supination range of motion. Larger differences were seen in supination at 2-4 cm of shortening and in pronation at 4-6 cm of shortening. Changes in supination were found to be associated with the radial bow and radioulnar gap; changes in pronation were found to be associated with the radial bow and radial bow's location.

CONCLUSIONS

This study demonstrates that quantifiable effects on passive forearm motion occur after osseous shortening of the forearm.

CLINICAL RELEVANCE

This information may improve surgeons' and patients' understanding of the changes in forearm motion expected after shortening in the setting of replantation or tumor resection or in the setting of limb salvage of a mangled extremity.

Assessing the Rotation of the First Metatarsal on Computed Tomography Scans: A Systematic Literature Review

BACKGROUND

Hallux valgus is a multiplanar deformity that is often treated on the basis of 2-dimensional (2D) parameters and radiographs. Recurrence rates after surgical correction remain high, and failure to correct pronation of the metatarsal is increasingly stipulated as being part of the problem. Multiple methods of assessing metatarsal pronation have been proposed.

METHODS

We performed a systematic literature review identifying studies that measured metatarsal pronation and torsion on computed tomography (CT) scans. Specific methodology, patient groups, results, and reliability assessments were all reported.

RESULTS

We identified 14 studies that fulfilled the inclusion criteria. Eleven studies measured 2D values on CT scan, and 3 studies used computer-based 3-dimensional (3D) modeling and artificial intelligence systems to help calculate pronation. Metatarsal pronation angle, α angle, sesamoid rotation angle, and measurements for torsion were the most commonly used methods. All angles and measurements were performed as 2D measurements, but the metatarsal pronation angle was also performed with 3D modeling. Reliability and reproducibility of the α angle and metatarsal pronation angle were excellent, despite being performed on studies with small numbers.

CONCLUSION

Multiple methods have been reported to demonstrate first metatarsal pronation on CT, of which the α angle and the metatarsal pronation angle are the most pragmatic and useful in a clinical setting. Further work is needed to further validate the reliability of these measurements in larger series and to identify normal pronation and metatarsal torsion on weightbearing imaging. Further work is required to determine whether addressing pronation reduces recurrence rates and improves outcomes in surgery for hallux valgus.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Effect of Systematic Corrective Exercises on the Static and Dynamic Balance of Patients with Pronation Distortion Syndrome: A Randomized Controlled Clinical Trial Study

Background:

The purpose of this study was to determine the effect of systematic corrective exercises on the static and dynamic balance of students with pronation distortion syndrome.

Methods:

In this randomized controlled clinical trial study, 30 volunteers were selected and randomly divided into the control and experimental groups (15 subjects per group). The experimental group performed systematic corrective exercises for 12 weeks, while the control group performed the routine exercise. Static and dynamic balance was evaluated before and after the interventions. The data were analyzed using independent and paired t-tests (P < 0.05).

Results:

The results showed significant improvement (P < 0.05) in the static and dynamic balance in the experimental group, but not in the control group. A significant difference was evident between the experimental and control groups in terms of static and dynamic balances, in static balance including Flamingo balance test (42.26 ± 5.35 vs. 10.13 ± 1.92) stabilometr (1.23 ± 0.48 vs. 3.71 ± 1.02), and in dynamic balance including star excursion balance test (anterior direction 82.4 ± 6.2 vs. 66.7 ± 6.9, Posterior-internal direction 87.8 ± 4.7 vs. 69.6 ± 6.3, posterior-external direction 86.06 ± 6.93 vs. 67.2 ± 6.2), stabilometr (3.8 ± 0.6 vs. 11.18 ± 1.8) (P < 0.05 for all variables).

Conclusions:

It can be concluded that systematic corrective exercises improve static and dynamic balance in students with pronation distortion syndrome and it could be recommended as modalities for these people.

Results after treatment of congenital radioulnar synostosis: a systematic review and pooled data analysis

Congenital radioulnar synostosis (CRUS) is one of the most common congenital disorders affecting the elbow and forearm, with the forearm being fixed in a range of positions usually varying from neutral rotation to severe pronation. The aim of this study, apart from a systematic review of all surgical procedures described for CRUS, is to derive any correlation between various influencing factors, outcomes and complications. This review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format by an electronic literature search of Ovid, MEDLINE and the Cochrane Library databases. Grading was according to the Newcastle-Ottawa scale and the Modified Coleman Methodology Score. Demographic data, surgical procedures, outcomes and complications were analyzed. Outcome data were pooled to establish means and ranges across all studies. Spearman correlations were performed. A total of 23 articles, showing a poor overall study quality (all Level of Evidence IV), met the inclusion criteria. A total of 374 forearms with a mean age of 6.7 years (2.0-18.8) were analyzed. Derotational surgeries were more commonly performed (91%) than motion-preserving surgeries (9%). The mean deformity improved from 64.8° pronation (-75° to 110°) to a mean of 2.8° pronation (-50° to 80°). In total, 17.9% of patients presented with complications. A significant correlation was noted between age and major complications, proximal osteotomies and complications, and postoperative loss of reduction and double level osteotomies as the primary treatment modality. Most of the complications occurred above the threshold of 65-70° of correction and in children 7 years and above. Surgery is essential to improve the quality of life of children with CRUS. However, each type of surgery is associated with complications, along with the respective hardware being used in rotation osteotomies. Caution is, nevertheless, warranted in interpreting these results in view of the inherent limitations of the included studies.

The Assessment of First Metatarsal Rotation in the Normal Adult Population Using Weightbearing Computed Tomography

BACKGROUND

The importance of the rotational profile of the first metatarsal is increasingly recognized in the surgical planning of hallux valgus. However, rotation in the normal population has only been measured in small series. We aimed to identify the normal range of first metatarsal rotation in a large series using weightbearing computed tomography (WBCT).

METHODS

WBCT scans were retrospectively analyzed for 182 normal feet (91 patients). Hallux valgus angle, intermetatarsal angle, anteroposterior/lateral talus-first metatarsal angle, calcaneal pitch, and hindfoot alignment angle were measured using digitally reconstructed radiographs. Patients with abnormal values for any of these measures and those with concomitant pathology, previous surgery, or hallux rigidus were excluded. Final assessment was performed on 126 feet. Metatarsal pronation (MPA) and α angles were measured on standardized coronal computed tomography slices. Pronation was recorded as positive. Intraobserver and interobserver reliability were assessed using intraclass correlation coefficients (ICCs).

RESULTS

Mean MPA was 5.5 ± 5.1 (range, -6 to 25) degrees, and mean α angle was 6.9 ± 5.5 (range, -5 to 22) degrees. When considering the normal range as within 2 standard deviations of the mean, the normal range identified was -5 to 16 degrees for MPA and -4 to 18 degrees for α angle. Interobserver and intraobserver reliability were excellent for both MPA (ICC = 0.80 and 0.97, respectively) and α angle (ICC = 0.83 and 0.95, respectively). There was a moderate positive correlation between MPA and α angle (Pearson coefficient 0.68, P < .001).

CONCLUSION

Metatarsal rotation is variable in normal feet. Normal MPA can be defined as less than 16 degrees, and normal α angle can be defined as less than 18 degrees. Both MPA and α angle are reproducible methods for assessing rotation. Further work is needed to evaluate these angles in patients with deformity and to determine their significance when planning surgical correction of hallux valgus.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

A Three-Dimensional Printed Foot Orthosis for Flexible Flatfoot: An Exploratory Biomechanical Study on Arch Support Reinforcement and Undercut

The advancement of 3D printing and scanning technology enables the digitalization and customization of foot orthosis with better accuracy. However, customized insoles require rectification to direct control and/or correct foot deformity, particularly flatfoot. In this exploratory study, we aimed at two design rectification features (arch stiffness and arch height) using three sets of customized 3D-printed arch support insoles (R+U+, R+U-, and R-U+). The arch support stiffness could be with or without reinforcement (R+/-) and the arch height may or may not have an additional elevation, undercutting (U+/-), which were compared to the control (no insole). Ten collegiate participants (four males and six females) with flexible flatfoot were recruited for gait analysis on foot kinematics, vertical ground reaction force, and plantar pressure parameters. A randomized crossover trial was conducted on the four conditions and analyzed using the Friedman test with pairwise Wilcoxon signed-rank test. Compared to the control, there were significant increases in peak ankle dorsiflexion and peak pressure at the medial midfoot region, accompanied by a significant reduction in peak pressure at the hindfoot region for the insole conditions. In addition, the insoles tended to control hindfoot eversion and forefoot abduction though the effects were not significant. An insole with stronger support features (R+U+) did not necessarily produce more favorable outcomes, probably due to over-cutting or impingement. The outcome of this study provides additional data to assist the design rectification process. Future studies should consider a larger sample size with stratified flatfoot features and covariating ankle flexibility while incorporating more design features, particularly medial insole postings.

Percutaneous Bunionette Correction Without Fixation: Clinical Results and Radiographic Evaluations Including Rotation of Metatarsal Head and Sagittal Angle Change of Fifth Metatarsal

Bunionette deformities have been treated as an analog of hallux valgus, and the surgical techniques are similar. Most commonly anteroposterior image is evaluated pre- and postoperatively. To our knowledge, only one study has evaluated changes on the lateral radiograph and no study has evaluated changes in rotation of the fifth metatarsal head postoperatively. In percutaneous bunionette correction using a burr for osteotomy, shortening of the fifth metatarsal and elevation of the metatarsal head are inevitable. Without fixation, there is also a possibility of rotational change to the metatarsal head. We measured parameters on anteroposterior and lateral weightbearing radiographs in 18 feet pre- and postoperatively. Rotation of the fifth metatarsal head was graded according to the medial tubercle location. We also evaluated angular change of the fifth metatarsal on weightbearing lateral radiographs. Percutaneous bunionette correction without fixation could achieve satisfactory clinical and radiographic results, with less complication, when compared with previously published outcomes of open and percutaneous surgery with fixation. In this surgical method, bunionette is corrected in 3 dimensions. To our knowledge, this is the first study to evaluate rotation of the metatarsal head and change in the sagittal angle of the fifth metatarsal after bunionette correction.

Correlation of Different Methods of Measuring Pronation of the First Metatarsal on Weightbearing CT Scans

BACKGROUND

There is no consensus in the foot and ankle literature regarding how to measure pronation of the first metatarsal in patients with hallux valgus. The primary purpose of this study was to compare 2 previously published methods for measuring pronation of the first metatarsal and a novel 3-dimensional measurement of pronation to determine if different measurements of pronation are associated with each other.

METHODS

Thirty patients who underwent a modified Lapidus procedure for their hallux valgus deformity were included in this study. Pronation of the first metatarsal was measured on weightbearing computed tomography (WBCT) scans using the α angle with reference to the floor, a 3-dimensional computer-aided design (3D CAD) calculation with reference to the second metatarsal, and a novel method, called the triplanar angle of pronation (TAP), that included references to both the floor (floor TAP) and base of the second metatarsal (second TAP). Pearson's correlation coefficients were used to determine if the 3 calculated angles of pronation correlated to each other.

RESULTS

Preoperative and postoperative α angle and 3D CAD had no correlation with each other (r = 0.094, P = .626 and r = 0.076, P = .694, respectively). Preoperative and postoperative second TAP and 3D CAD also had no correlation (r = 0.095, P = .624 and r = 0.320, P = .09, respectively). However, preoperative and postoperative floor TAP and α angle were found to have moderate correlations (r = 0.595, P = .001 and r = 0.501, P = .005, respectively).

CONCLUSION

The calculation of first metatarsal pronation is affected by the reference and technique used, and further work is needed to establish a consistent measurement for the foot and ankle community.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Frontal Plane Rotation of the First Ray in Hallux Valgus using Standing Computerized Tomography (CT)

The purpose of the present study was to analyze the difference in frontal plane rotation of the entire first ray in patients with and without hallux valgus using standing weightbearing computed tomography (CT). Ten feet of 10 patients with hallux valgus and 36 feet of 36 patients without hallux valgus were examined. Standing weightbearing CT scans and radiographs were taken for all subjects. Frontal plane measurements of the sesamoid apparatus, first metatarsal head, first metatarsal base, and medial cuneiform were performed. Frontal plane rotation of the first tarsometatarsal joint and intrinsic first metatarsal torsion was calculated. An independent 2 sample t test was used to compare means of outcomes of interest across control and treatment groups. Statistical significance was set at an alpha level of 0.05. There was a significant increase in pronation of the sesamoid apparatus (23.49° vs 6.60°) and first metatarsal head (17.79° vs 9.81°) in patients with hallux valgus. There was a significant increase in first metatarsal torsion toward pronation in patients with hallux valgus (22.28° vs 13.52°). No significant difference was detected in the rotation at the first tarsometatarsal joint or the frontal plane orientations of the first metatarsal base and medial cuneiform. By examining the frontal plane position of the entire first ray during weightbearing using standing CT in patients with and without hallux valgus, we determined the level at which pronation originates to be within the first metatarsal bone rather than the first tarsometatarsal joint.

Custom-Made Foot Orthoses as Non-Specific Chronic Low Back Pain and Pronated Foot Treatment

Excessive foot pronation has been reported as being related to chronic low back pain symptoms and risk factors in sports-specific pathologies. Compensating custom-made foot orthotics treatment has not been entirely explored as an effective therapy for chronic low back pain (CLBP). This study aims to observe the effects of custom-made foot orthoses, in subjects with foot pronation suffering from CLBP. A total of 101 patients with nonspecific CLBP and a pronated foot posture index (FPI) were studied. They were randomized in two groups: an experimental one (n = 53) used custom-made foot orthotics, and the control group (n = 48) were treated with non-biomechanical effect orthoses. The CLBP was measured using the Oswestry Disability Index (ODI) Questionnaire and a visual analogue scale (VAS), both for lower back pain. The symptoms were evaluated twice, at first when the subject was included in the study, and later, after 4 weeks of treatment. The analysis of outcomes showed a significant decrease in CLBP in the custom-made foot orthoses participants group (p < 0.001 ODI; p < 0.001 VAS). These findings suggest that controlling excessive foot pronation by using custom-made foot orthoses may significantly contribute to improving CLBP.

The Assessment of First Metatarsal Rotation in the Normal Adult Population Using Weightbearing Computed Tomography

BACKGROUND

The importance of the rotational profile of the first metatarsal is increasingly recognized in the surgical planning of hallux valgus. However, rotation in the normal population has only been measured in small series. We aimed to identify the normal range of first metatarsal rotation in a large series using weightbearing computed tomography (WBCT).

METHODS

WBCT scans were retrospectively analyzed for 182 normal feet (91 patients). Hallux valgus angle, intermetatarsal angle, anteroposterior/lateral talus-first metatarsal angle, calcaneal pitch, and hindfoot alignment angle were measured using digitally reconstructed radiographs. Patients with abnormal values for any of these measures and those with concomitant pathology, previous surgery, or hallux rigidus were excluded. Final assessment was performed on 126 feet. Metatarsal pronation (MPA) and α angles were measured on standardized coronal computed tomography slices. Pronation was recorded as positive. Intraobserver and interobserver reliability were assessed using intraclass correlation coefficients (ICCs).

RESULTS

Mean MPA was 5.5 ± 5.1 (range, -6 to 25) degrees, and mean α angle was 6.9 ± 5.5 (range, -5 to 22) degrees. When considering the normal range as within 2 standard deviations of the mean, the normal range identified was -5 to 16 degrees for MPA and -4 to 18 degrees for α angle. Interobserver and intraobserver reliability were excellent for both MPA (ICC = 0.80 and 0.97, respectively) and α angle (ICC = 0.83 and 0.95, respectively). There was a moderate positive correlation between MPA and α angle (Pearson coefficient 0.68, P < .001).

CONCLUSION

Metatarsal rotation is variable in normal feet. Normal MPA can be defined as less than 16 degrees, and normal α angle can be defined as less than 18 degrees. Both MPA and α angle are reproducible methods for assessing rotation. Further work is needed to evaluate these angles in patients with deformity and to determine their significance when planning surgical correction of hallux valgus.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Assessment of Selected Spatio-Temporal Gait Parameters on Subjects with Pronated Foot Posture on the Basis of Measurements Using OptoGait. A Case-Control Study

Walking is part of daily life and in asymptomatic subjects it is relatively easy. The physiology of walking is complex and when this complex control system fails, the risk of falls increases. As a result, gait disorders have a major impact on the older adult population and have increased in frequency as a result of population aging. Therefore, the OptoGait sensor is intended to identify gait imbalances in pronating feet to try to prevent falling and injury by compensating for it with treatments that normalize such alteration. This study is intended to assess whether spatiotemporal alterations occur in the gait cycle in a young pronating population (cases) compared to a control group (non-pronating patients) analyzed with OptoGait. Method: a total of n = 142 participants consisting of n = 70 cases (pronators) and n = 72 healthy controls were studied by means of a 30 s treadmill program with a system of 96 OptoGait LED sensors. Results: Significant differences were found between the two groups and both feet in stride length and stride time, gait cycle duration and gait cadence (in all cases p < 0.05). Conclusions: pronating foot posture alters normal gait patterns measured by OptoGait; this finding presents imbalance in gait as an underlying factor. Prevention of this alteration could be considered in relation to its relationship to the risk of falling in future investigations.

Functional Morphology of the Feeding Apparatus of the Snaggletooth Shark, Hemipristis elongata (Carcharhiniformes: Hemigaleidae)

The anatomy of the feeding apparatus of the snaggletooth shark, Hemipristis elongata (Klunzinger, 1871) is illustrated in detail from the dissection of three heads. Two new muscles are described: the Adductor mandibularis internus and the Levator mandibularis. A subdivision of the Levator palatoquadrati is described and named the Pronator subdivision of the Levator palatoquadrati. Also, eight new anatomical features associated with the mandibular arch and with the chondrocranium (CR) are described. Three are cartilages: the suprapalatine cartilages, the craniopalatoquadrate cartilage and the calcified Meckelian dental fold. The remaining five features are processes: the Pronator process of the palatoquadrate (PQ), the Levator palatoquadrati alpha process, the proquadrate process, the ectorbital process (ECP) and the Meckelian Intermandibularis ridge. Some of them are not restricted to H.elongata. The function of these new muscles and anatomical features is discussed and a hypothesis about the functional morphology of the feeding apparatus of the snaggletooth shark is proposed. The extent and the assumptive importance of the pronation of the mandibular arch in the snaggletooth shark feeding behaviour is described and discussed. An alternative for the main function of the Levator palatoquadrati as hypothesized by Motta et al. (1997) and Wilga et al. (2001) is proposed for the families Hemigaleidae, Carcharhinidae and Sphyrnidae. We anticipate this muscle is more involved in the pronation rather than in the protrusion of the mandibular arch.

Crosstalk in Mechanomyographic Signals From Elbow Flexor Muscles During Submaximal to Maximal Isometric Flexion, Pronation, and Supination Torque Tasks

This study analyzed the crosstalk in mechanomyographic (MMG) signals from elbow flexors during isometric muscle actions from 20% to 100% maximum voluntary isometric contraction (MVIC). Twenty-five young, healthy, male participants performed the isometric elbow flexion, forearm pronation, and supination tasks at an elbow joint angle of 90 deg. The MMG signals from the biceps brachii (BB), brachialis (BRA), and brachioradialis (BRD) muscles were recorded using accelerometers. The cross-correlation coefficient was used to quantify the crosstalk in MMG signals, recorded in a direction transverse to muscle fiber axis, among the muscle pairs (P1: BB and BRA, P2: BRA and BRD, and P3: BB and BRD). In addition, the MMG RMS and MPF were quantified. The mean normalized RMS and mean MPF exhibited increasing (r > 0.900) and decreasing (r < -0.900) trends, respectively, with increases in the effort levels in all three tasks. The magnitude of crosstalk ranged from 0.915% to 21.565% in all three muscle pairs. The crosstalk was found to exhibit high positive correlations with submaximal to maximal flexion [P1 (r = 0.970), P2 (r = 0.951), and P3 (r = 0.824)], pronation [P1 (r = 0.811), P2 (r = 0.763), and P3 (r = 0.901)] and supination [P1 (r = 0.898), P2 (r = 0.838), and P3 (r = 0.852)] torque levels (eight out of nine p-values were < 0.05). Regardless of the high positive correlation between crosstalk and level of effort, the crosstalk remained at a low range (0.915-21.565%) with increases in the torque levels.

The Rotational Positioning of the Bones in the Medial Column of the Foot: A Weightbearing CT Analysis

BACKGROUND

Malrotation of medial column bones of the foot has been advocated as an important factor in foot conditions such as hallux valgus and progressive collapsing foot deformity. Although stated as a deformity component, variances of normality in the general population are not completely understood. This study intended to describe the rotational profile of all medial column bones using weightbearing computed tomography (WBCT) images in a cohort of patients with different foot and ankle problems.

METHODS

In this retrospective study, 110 feet of 95 consecutive patients that received a WBCT for assessment of different foot and ankle pathologies were included. Measurements were performed by a blinded fellowship-trained orthopedic foot and ankle surgeon. Rotation of the navicular, medial cuneiform, proximal and distal first metatarsal as well as proximal phalanx of the first toe were recorded. Positive values were considered pronation and negative values were considered supination. Rotational profile of each bone/ segment was assessed by ANOVA and comparison between each segment was performed using Wilcoxon Each-Pair analysis. P-values of less than 0.05 were considered significant.

RESULTS

On average, a rotational positioning in pronation (internal rotation) was observed for all medial column bones. The navicular (43.2°, CI 41.1°-45.3°) and the proximal metatarsal (33.9°, CI 31.8°-36.0°) showed the highest mean rotation values. The medial cuneiform presented the lowest mean pronation (6.1°, CI 4.0°-8.3°). Comparison between each bone segment demonstrated statistically significant differences of rotational alignment for the different bones (p<0.0001), with the exception of the distal metatarsal and proximal phalanx, that had similar amounts of pronation. A zig-zag rotational pattern of alignment was observed from proximal to distal, with relative supination/pronation of adjacent medial column bones.

CONCLUSION

The overall rotational profile of medial column bones was found to be in absolute pronation, most pronounced at the navicular and proximal first metatarsal, with significant differences in the amount of pronation when comparing most of the medial column bones. The presented data may be utilized as reference/ baseline values of medial column rotation, supporting future prospective, comparative and controlled studies.Level of Evidence: IV.

Feature Analysis of Smart Shoe Sensors for Classification of Gait Patterns

Gait analysis is commonly used to detect foot disorders and abnormalities such as supination, pronation, unstable left foot and unstable right foot. Early detection of these abnormalities could help us to correct the walking posture and avoid getting injuries. This paper presents extensive feature analyses on smart shoes sensor data, including pressure sensors, accelerometer and gyroscope signals, to obtain the optimum combination of the sensors for gait classification, which is crucial to implement a power-efficient mobile smart shoes system. In addition, we investigated the optimal length of data segmentation based on the gait cycle parameters, reduction of the feature dimensions and feature selection for the classification of the gait patterns. Benchmark tests among several machine learning algorithms were conducted using random forest, k-nearest neighbor (KNN), logistic regression and support vector machine (SVM) algorithms for the classification task. Our experiments demonstrated the combination of accelerometer and gyroscope sensor features with SVM achieved the best performance with 89.36% accuracy, 89.76% precision and 88.44% recall. This research suggests a new state-of-the-art gait classification approach, specifically on detecting human gait abnormalities.

Finite Element Analysis of Generalized Ligament Laxity on the Deterioration of Hallux Valgus Deformity (Bunion)

Hallux valgus is a common foot problem affecting nearly one in every four adults. Generalized ligament laxity was proposed as the intrinsic cause or risk factor toward the development of the deformity which was difficult to be investigated by cohort clinical trials. Herein, we aimed to evaluate the isolated influence of generalized ligament laxity on the deterioration using computer simulation (finite element analysis). We reconstructed a computational foot model from a mild hallux valgus participant and conducted a gait analysis to drive the simulation of walking. Through parametric analysis, the stiffness of the ligaments was impoverished at different degrees to resemble different levels of generalized ligament laxity. Our simulation study reported that generalized ligament laxity deteriorated hallux valgus by impairing the load-bearing capacity of the first metatarsal, inducing higher deforming force, moment and malalignment at the first metatarsophalangeal joint. Besides, the deforming moment formed a deteriorating vicious cycle between hallux valgus and forefoot abduction and may result in secondary foot problems, such as flatfoot. However, the metatarsocuneiform joint did not show a worsening trend possibly due to the overriding forefoot abduction. Controlling the deforming load shall be prioritized over the correction of angles to mitigate deterioration or recurrence after surgery.

Randomized Clinical Trial: The Effect of Exercise of the Intrinsic Muscle on Foot Pronation

Background: There is little scientific evidence regarding the effectiveness of strengthening exercises on the foot's intrinsic musculature in improving the lower limb on the statics and dynamics in healthy individuals. Method: To evaluate the effect on foot posture with regard to the reinforcement of the short foot exercise (SFE) compared to another without a recognized biomechanical action, which we called the "non-biomechanical function" (NBF) exercise. A randomized clinical trial was carried out with 85 asymptomatic participants with a bilateral Foot Posture Index (FPI) greater than 6 points. An experimental group (n = 42) did SFE training and a control group (n = 43) carried out NBF exercises. The foot posture was evaluated twice via the navicular drop (ND) test, and the FPI was assessed on the day of inclusion in the study (pre-intervention) and after four weeks of training (post-intervention). Results: Statistically significant values were not found in foot posture between the experimental and the control groups when comparing before and after the training. However, the foot posture was modified in both groups with respect to its initial state, and the ND value decreased. Conclusions: SFE could be considered a useful tool to deal with pathologies whose etiology includes excessive pronation of the foot.