Static Range of Motion of the First Metatarsal in the Sagittal and Frontal Planes

Evaluation of first ray instability using the double dorsiflexion test: A prospective observational case-controlled study

BACKGROUND

First-Ray (FR) stability allows for foot propulsion in-stance, taking 60% weight. First-ray instability (FRI) is associated with middle column overload, synovitis, deformity and osteoarthritis. Clinical detection can still be challenging. We propose to develop a clinical test that helps identify FRI using two simple manual manoeuvres.

METHODS

10 patients with unilateral FRI were recruited. Unaffected contralateral feet were used as controls. Stringent exclusion criteria were applied including hallux MTP pain, laxity, inflammatory arthropathy and collagen disorders. A Klauemeter directly measured the sagittal plane dorsal first metatarsal head translation of affected vs unaffected feet. Maximum passive proximal phalanx 1st MTP joint dorsiflexion was measured using a video capture and Tracker motion software analysis with and without applying a dorsal force at the 1st metatarsal head using a Newton meter. Proximal phalanx motion was compared in affected vs unaffected feet with and without dorsal metatarsal head force application and compared to direct measurements using the Klaumeter. P value of < 0.05 was considered significant.

RESULTS

FRI feet had dorsal translation greater than 8 mm (median, 11.94; interquartile range [IQR], 10.23-13.81) vs 1.77 for unaffected control feet was (median, 1.77; interquartile range [IQR], 1.23-2.96) using the Klauemeter. The percentage reduction in 1st MTP joint dorsiflexion ROM when applying the double dorsiflexion test FRI (mean reduction of 67.98%) when compared to control feet (mean reduction of 28.44%)(P < 0.01). Receiver operating characteristic (ROC) analysis showed that a 50% reduction in dorsiflexion ROM of 1st MTPJ when performing the double dorsiflexion test achieved a specificity of 100% and sensitivity of 90% (AUC =0.990, 95%CI [0.958-1.000], P > 0.0001).

CONCLUSION

The double dorsiflexion (DDF) is easy to perform with two relatively simple manual manoeuvres that avoids the need for complex instrumented and radiation-based assessment. Greater than 50% decrease in proximal phalanx motion has an over 90% sensitivity in identifying feet with FRI.

LEVEL OF EVIDENCE

This was a prospective case-controlled study of consecutive cases of a level II evidence.

An Operational Definition of First Ray Hypermobility

BACKGROUND

The first ray (metatarsocuneiform) behaves as a load-bearing strut in supporting weight. Due to its functional importance, stress-testing techniques are used to assess the stability of the first ray and objectify evidence of hypermobility. The test and measurement of first ray hypermobility (FRH) is of interest to clinicians and researchers. The condition itself, however, has proven elusive to diagnose. This article defines FRH for the purpose of improving the consistency by which the diagnosis is made. Currently, the lack of a consensus definition prevents research from determining the incidence rates and prevalence of FRH, a commonly reported medical condition.

THE DEFINITION

Symptomatic FRH presents as dorsal displacement that measures greater than 8 mm, accompanied with signs and symptoms consistent with loading insufficiency of the first ray. The operational definition is objective and if adopted across health care professions, the criterion could become the standard for identifying FRH in patients and research participants.

LEVEL OF EVIDENCE

Level V, expert opinion.

Pathophysiological Behaviour of the Climber's Foot versus the General Population: A Prospective Observational Study

Sport climbing is becoming increasingly popular, with people of all types and ages practising it. The feet suffer a lot of pressure with the sport climbing gesture, which in the long run can produce alterations in the first metatarsophalangeal joint or in the first radius of the foot. Objective: To observe and quantify the behaviour of the foot in climbing subjects compared to a group of non-climbing subjects, comparing the pressures, first metatarsophalangeal joint and first radius of the foot. Method: This is a non-experimental and observational, cross-sectional, descriptive and prospective research. The study sample consisted of 105 subjects (42 males and 63 females). The control group consisted of 52 subjects and the climbing group consisted of 53 subjects. Different exploratory tests were carried out on all the subjects, such as: mobility of the metatarsophalangeal joint and first radius of the foot and the study of plantar pressures in different areas of the study. Results: No significant difference was found between left and right foot measurements (p > 0.05). The pressures of the same foot are significant, both at static and dynamic stages for both groups. The maximum pressure in the climbing group was under the first metatarsal head, while in the control group it was under the second metatarsal head. There were significant differences in the mobility of the first metatarsal joint and the first radius between the two groups. Conclusion: It can be seen that the group of climbers has less plantar pressure than the control group. They also have altered mobility of the first radius and the first metatarsophalangeal joint.

Is the Planus Foot Type Associated With First Ray Hypermobility?

Background:

Many foot pathologies have been associated with foot type. However, the association of first ray hypermobility remains enigmatic. The purpose of this study was to investigate first ray hypermobility among participants with planus and rectus foot types and its influence on static measures of foot structure.

Methods:

Twenty asymptomatic participants with planus (n = 23 feet) and rectus (n = 17 feet) foot types were enrolled. Several parameters of static foot structure (arch height index, arch height flexibility, first metatarsophalangeal joint flexibility, and first ray mobility) were measured. Participants were further stratified into groups with nonhypermobile (n = 26 feet) and hypermobile (n = 14 feet) first rays. First ray mobility ≥8 mm was used to define “first ray hypermobility”. Generalized estimating equations, best-fit regression lines, and stepwise linear regression were used to identify significant differences and predictors between the study variables

Results:

Overall, 86% of subjects categorized with first ray hypermobility exhibited a planus foot type. Arch height flexibility, weightbearing first ray mobility, and first metatarsophalangeal joint flexibility showed no significant between-group differences. However, weightbearing ray mobility and first metatarsophalangeal joint laxity were associated with partial weightbearing first ray mobility, accounting for 38% of the model variance.

Conclusion:

The planus foot type was found to be associated with first ray hypermobility. Furthermore, weightbearing first ray mobility and first metatarsophalangeal joint laxity were predictive of partial weightbearing first ray mobility, demonstrating an interaction between the translation and rotational mechanics of the first ray.

Clinical Relevance:

Association of first ray hypermobility with foot type and first metatarsophalangeal joint flexibility may help understand the sequela to symptomatic pathologies of the foot.

Surrogate lower limb design for ankle-foot orthosis mechanical evaluation

Purpose

This study designs and provides a pilot evaluation of a novel surrogate lower limb (SLL) that provides anatomically realistic three-dimensional (3D) foot motion, based on a literature consensus of passive lower limb motion. This SLL is intended to replace single axis surrogates currently used in mechanical testing of ankle-foot orthoses (AFO).

Material and Methods

The SLL design is inspired by the Rizzoli foot model, with shank, hindfoot, midfoot, forefoot, and toe sections. Ball and socket joints were used between hindfoot-midfoot (HM)-forefoot sections. Forefoot-toes used a hinge joint. Three-dimensional printed nylon, thermoplastic polyurethane (TPU) and polylactic acid (PLA), as well as casted silicone rubber were used to re-create foot components. After fabrication, motion capture was performed to measure rotation using fiducial markers. The SLL was then loaded under both static and cyclic loads representing a 100 kg person walking for 500,000 cycles.

Results

Most joints were within 5° of target angles. The SLL survived static loads representing 1.5 times body weight for both static and cyclical loading.

Conclusions

This SLL moved as designed and survived testing loads, warranting further investigation towards enabling essential mechanical testing for AFO currently on the market, and helping to guide device prescription.

Comparative Reliability of a Novel Electromechanical Device and Handheld Ruler for Measuring First Ray Mobility

BACKGROUND

Quantifying first ray mobility is crucial to understand aberrant foot biomechanics. A novel device (MAP1^st) that can perform measurements of first ray mobility in different weightbearing conditions, foot alignments, and normalization was tested. The reliability of these measurement techniques was assessed in comparison to a handheld ruler considered representative of the common clinical examination.

METHODS

The study included 25 participants (50 feet). Two independent raters performed baseline, test-retest, and remove-replace measurements of first ray mobility with MAP1^st and the handheld device. The effects of non-, partial, and full weightbearing in subtalar joint neutral and the resting calcaneal stance position were assessed. Measurement normalization relative to foot size was also investigated. Intra- and interclass correlation coefficients (ICCs) were calculated for each device between the 2 raters. In addition, Bland-Altman plots were constructed to determine if fixed biases or substantial outliers were present.

RESULTS

Similar intrarater ICC values were found for both devices (≥0.85). However, interrater ICC values were substantially improved by MAP1^st compared with the handheld device (0.58 vs 0.06). Bland-Altman plots demonstrated biases of 1.27 mm for the handheld ruler, and 2.88 to 0.05 mm and -1.16 to 0.00 for linear and normalized MAP1^st measurements, respectively. Improved reliability was achieved with MAP1^st for normalized assessments of first ray mobility while the foot was placed in partial- and full-weightbearing resting calcaneal stance positions.

CONCLUSION

MAP1^st provided reliable assessments of partial- and full-weightbearing first ray mobility. It should help investigators to explore the potential relationships between first ray function and aberrant foot biomechanics in future research.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Hypermobility of the First Ray: the Cinderella of the measurements conventionally assessed for correction of Hallux Valgus

Background and aim of the work:

hypermobility of the first ray (FRH) began to be considered as a pathological entity from Morton’s studies and was associated as a primary cause of hallux valgus (HV). Currently, this relationship is in discussion, and various authors consider FRH as a consequence of the deformity. The purpose of this narrative review is to summarise the most influential publications relating to First Ray Mobility (FRM) to increase knowledge and promote its conventional assessment during clinical practice.

Methods:

papers of the last century were selected to obtain a homogeneous and up-to-date overview of I-MTCJ mobility and HV, as well as their relationship and management.

Results:

in recent years, FRH was studied from a biomechanical and pathophysiologic point of view. There is still not enough data regarding the aetiology of FRM. The higher rate of instability found in HV lacks an explanation of which is the cause and which is the effect. However, the Lapidus arthrodesis is still a valid method in cases of FRH and HV, even if is not rigorously indicated to treat both. When approaching FRH, radiographic or clinical findings are mandatory for the right diagnosis.

Conclusions:

FRM is an important factor that must be considered in routine clinical practice and prior and post HV surgery, as much as the conventional parameters assessed. Surgeons should consider performing I-MTCJ arthrodesis only if strictly necessary, also paying attention to soft tissue balancing. Improving the measurement of FRH could be useful to determine if it is a cause or effect of the HV deformity. (www.actabiomedica.it)

The Validity and Reliability of a New Simple Instrument for the Measurement of First Ray Mobility

Several methods have been described to quantify the first ray mobility. They all have certain disadvantages (great size, sophistication, or lack of validation). The objective of this work was to study the validity and reliability of a new instrument for the measurement of first ray mobility. Anterior-posterior radiographs were obtained from 25 normal feet and 24 hallux valgus feet, with the first ray in a neutral position, maximally dorsiflexed and maximally plantarflexed. The first ray mobility was radiographicaly measured in both groups, and was also manually examined with the new device. A cluster analysis determined whether normal and hallux valgus feet were correctly classified, and a graphic analysis of Bland-Altman was performed to compare the radiographic and manual measurement techniques. Based on the radiographs, the first ray mobility only showed significant differences in dorsiflexion between both groups (P = 0.015). First ray dorsiflexion, plantarflexion and total range of motion measured with the new device were different between both groups (P = 0.040, P = 0.011 and P = 0.006, respectively). The silhouette measure of the cohesion and separation coefficients from the cluster analysis was greater than 0.50 for the dorsiflexion, plantarflexion and total range of motion obtained from the radiographs and from the new device. The Bland-Altman graph suggested that 96% of the data presented agreement between both measurement methods. These results suggested that the new instrument was valid and reliable.

Immediate and short-term radiological changes after combining static stretching and transcutaneous electrical stimulation in adults with cavus foot: A randomized controlled trial

BACKGROUND

Cavus foot is a deformity represented by an increased and rigid medial longitudinal arch, and it is often associated with persistent pain and gait disturbances. None of the conservative conventional treatments for cavus foot have shown conclusive evidence of effectiveness, and so further is research needed to understand how to manage this condition better. This study aimed to assess the immediate and short-term radiological changes after combining static stretching and transcutaneous electrical stimulation of the plantar fascia in adults with idiopathic cavus foot.

METHODS

A randomized, single-blinded clinical trial was conducted. Sixty-eight participants with idiopathic cavus foot, as determined by an internal Moreau-Costa-Bertani angle (MCBA) less than 125° in a lateral weight-bearing foot radiograph, were equally distributed into a neuromuscular stretching group (NSG) or a control group (no intervention). The NSG underwent a single session, combining transcutaneous electrical nerve stimulation with static stretching of the plantar fascia. Primary measurements of 3 angles were taken using a lateral weight-bearing foot radiograph: the internal MCBA; the calcaneal pitch angle (CPA); and the first metatarsal declination angle (FMDA). Outcomes were collected at baseline, immediately postintervention, and 1 week after intervention.

RESULTS

Analysis of variance revealed a significant group effect for all angles (all, P < .05). NSG participants showed a significant increase in the internal MCBA (P = .03), and a significant decrease in the CPA (P = .01) and FMDA (P = .04) from baseline to immediately postintervention. These changes remained statistically significant 1 week after the intervention (all, P < .05).

CONCLUSION

The combination of static stretching and transcutaneous electrical stimulation of the plantar fascia, compared with no treatment, achieved immediate and short-term changes in the internal MCBA, the CPA, and the FMDA, which resulted in flattening the medial longitudinal plantar arch in adults with idiopathic cavus foot.

Measurement of Dorsal First Ray Mobility: A Topical Historical Review and Commentary

Despite evidence that instability of the first ray (first metatarsal and medial cuneiform) alters the loading mechanics of the foot, surprisingly few studies have linked the condition with disorders of the foot. A factor limiting this research is the difficulty associated with measuring first ray mobility (FRM). To quantify dorsal FRM, clinicians and researchers have devised a variety of methods that impose a dorsally directed load, and record displacement. The methods include manual examination, radiographs, mechanical devices, and handheld rulers. Since different methods yield different results; each of these methods is worthy of scrutiny. This article reviews the methods used to quantify dorsal FRM and offers commentary on how the testing procedures could be standardized. The measurement of dorsal FRM informs surgical decisions, orthotic prescriptions, and research design strategies mostly as it pertains to the identification and treatment of first ray hypermobility. This review found sufficient support to recommend continued use of radiographs and mechanical devices for quantifying dorsal displacement, whereas measurements acquired with handheld rulers are prone to the same subjective error attributed to manual examination procedures. Since measures made with radiographs and existing mechanical devices have their own drawbacks, the commentary recommends ideas for standardizing the testing procedure and calls for the development of a next-generation device to measure dorsal FRM. This future device could be modeled after arthrometers that exist and are used to quantify stability at the knee and ankle. Level of Evidence: Level V, expert opinion.