The biomechanical relationship between the tendoachilles, plantar fascia and metatarsophalangeal joint dorsiflexion angle

Differences and Similarities in the Feet of Metatarsalgia Patients with and without Rheumatoid Arthritis in Remission

Objectives: Metatarsalgia continues to be a problem in patients with rheumatoid arthritis (RA) in remission (remRA), as well as in the non-rheumatic population, with a mechanical origin. Identify and compare clinical, morphological, disability, synovitis (ultrasound), and radiological osteoarticular damage characteristics in two groups of patients with lesser-ray metar-tarsalgia, with remRA, and without RA. Methods: Cross-sectional study with 84 patients with remRA (mRA) and 60 patients without RA (nmRA). The study evaluated five clinical variables (pain, Foot Function Index (FFI), joint mobility, digital deformities, and foot type), a radiological variable (osteoarticular damage), and an ultrasound variable (metatarsal synovitis). The data were analysed using descriptive and correlational techniques. Results: There were no significant differences in sex, age, body mass index (BMI), or degree of pain. Both groups showed a high prevalence of limited joint mobility for the ankle and first metatarsal phalanx (DF1st MTPJ) and digital deformities, with no statistically significant differences. Similarly, there were no differences in lesser-ray synovitis. On the other hand, there were differences in mRA with greater disability and activity limitation (FFI), LDD (lesser-ray digital deformities) stiffness, first-ray deformities, radiological damage, synovitis in 1st MTPJ, and positive Doppler (five patients). Conclusions: Metatarsalgia presents similarities in both populations. Biomechanical factors may influence the symptoms and presence of synovitis in patients with RA in remission. Other characteristics are more frequent in mRA, which could be related to the disease; thus, future research should include both biomechanical and ultrasound exploration of the foot in the valuation of patients in remission.

Do the fasciae of the soleus have a role in plantar fasciitis?

Plantar fasciitis is a chronic, self-limiting, and painful disabling condition affecting the inferomedial aspect of the heel, usually extending toward the metatarsophalangeal joints. There is compelling evidence for a strong correlation between Achilles tendon (AT) loading and plantar aponeurosis (PA) tension. In line with this, tightness of the AT is found in almost 80% of patients affected by plantar fasciitis. A positive correlation has also been reported between gastrocnemius-soleus tightness and heel pain severity in this condition. Despite its high prevalence, the exact etiology and pathological mechanisms underlying plantar heel pain remain unclear. Therefore, the aim of the present paper is to discuss the anatomical and biomechanical substrates of plantar fasciitis with special emphasis on the emerging, though largely neglected, fascial system. In particular, the relationship between the fascia, triceps surae muscle, AT, and PA will be analyzed. We then proceed to discuss how structural and biomechanical alterations of the muscle-tendon-fascia complex due to muscle overuse or injury can create the conditions for the onset of PA pathology. A deeper knowledge of the possible molecular mechanisms underpinning changes in the mechanical properties of the fascial system in response to altered loading and/or muscle contraction could help healthcare professionals and clinicians refine nonoperative treatment strategies and rehabilitation protocols for plantar fasciitis.

Impact of pronated foot on energetic behavior and efficiency during walking

BACKGROUND

The longitudinal arch of the foot acts like a spring during stance and contributes to walking efficiency. Pronated foot characterized by a collapsed medial longitudinal arch may have the impaired spring-like function and poor walking efficiency. However, the differences in the energetic behavior during walking between individuals with pronated foot and neutral foot have not been considered.

RESEARCH QUESTION

How does the energetic behavior within the foot and proximal lower limb joints in pronated foot affect walking efficiency?

METHODS

Twenty-one healthy young adults were classified into neutral foot and pronated foot based on the Foot Posture Index score. All subjects walked across the floor and attempted to have the rearfoot and forefoot segments contact separate force plates to analyze the forces acting on isolated regions within the foot. Kinematic and kinetic data were recorded by a three-dimensional motion capture system. The hip, knee, ankle, and mid-tarsal joint power was quantified using a 6-degree-of-freedom joint power method. To qualify total power within all structures of the foot and forefoot, we used a unified deformable segment analysis. Additionally, we calculated the center of mass power to quantify the total power of the whole body RESULTS: There is no difference in the mid-tarsal joint work between the pronated foot and neutral foot. On the other hand, pronated foot exhibited greater net negative work at structures distal to the forefoot during walking. Additionally, pronated foot exhibited less net positive work at the ankle and center of mass during walking compared to neutral foot.

SIGNIFICANCE

Individuals with pronated foot generate the mid-tarsal joint work by increasing the work absorbed at structures distal to the forefoot, which results in reduced energy efficiency during walking. That energy inefficiency may reduce positive work at the ankle and affect the walking efficiency in individuals with pronated foot.

Effects of different habitual foot strike patterns on in vivo kinematics of the first metatarsophalangeal joint during shod running-a statistical parametric mapping study

Existing studies on the biomechanical characteristics of the first metatarsophalangeal joint (1st MTPJ) during shod running are limited to sagittal plane assessment and rely on skin marker motion capture, which can be affected by shoes wrapping around the 1st MTPJ and may lead to inaccurate results. This study aims to investigate the in vivo effects of different habitual foot strike patterns (FSP) on the six degrees of freedom (6DOF) values of the 1st MTPJ under shod condition by utilizing a dual-fluoroscopic imaging system (DFIS). Long-distance male runners with habitual forefoot strike (FFS group, n = 15) and rearfoot strike (RFS group, n = 15) patterns were recruited. All participants underwent foot computed tomography (CT) scan to generate 3D models of their foot. The 6DOF kinematics of the 1st MTPJ were collected using a DFIS at 100 Hz when participants performed their habitual FSP under shod conditions. Independent t-tests and one-dimensional statistical parametric mapping (1-d SPM) were employed to analyze the differences between the FFS and RFS groups' 1st MTPJ 6DOF kinematic values during the stance phase. FFS exhibited greater superior translation (3.5-4.9 mm, p = 0.07) during 51%-82% of the stance and higher extension angle (8.4°-10.1°, p = 0.031) during 65%-75% of the stance in the 1st MTPJ than RFS. Meanwhile, FFS exhibited greater maximum superior translation (+3.2 mm, p = 0.022), maximum valgus angle (+6.1°, p = 0.048) and varus-valgus range of motion (ROM) (+6.5°, p = 0.005) in the 1st MTPJ during stance. The greater extension angle of the 1st MTPJ in the late stance suggested that running with FFS may enhance the propulsive effect. However, the higher maximum valgus angle and the ROM of varus-valgus in FFS may potentially lead to the development of hallux valgus.

Effect of painful Ledderhose disease on dynamic plantar foot pressure distribution during walking: a case-control study

BACKGROUND

Plantar pressure distribution during walking in patients with painful Ledderhose disease is unknown.

RESEARCH QUESTION

Do patients with painful Ledderhose disease have an altered plantar pressure distribution during walking compared to individuals without foot pathologies? It was hypothesized that plantar pressure is shifted away from the painful nodules.

METHODS

Pedobarography data of 41 patients with painful Ledderhose disease (cases, mean age: 54.2 ± 10.4 years) was collected and compared to pedobarography data from 41 individuals without foot pathologies (controls, mean age: 21.7 ± 2.0 years). Peak Pressure (PP), Maximum Mean Pressure (MMP) and Force-Time Integral (FTI) were calculated for eight regions (heel, medial midfoot, lateral midfoot, medial forefoot, central forefoot, lateral forefoot, hallux and other toes) under the soles of the feet. Differences between cases and controls were calculated and analysed by means of linear (mixed models) regression.

RESULTS

Proportional differences in PP, MMP and FTI showed increased values for the cases compared to the controls, especially in the heel, hallux and other toes regions, and decreased values in the medial- and lateral midfoot regions. In naïve regression analysis, being a patient was a predictor for increased- and decreased values for PP, MMP and FTI for several regions. When dependencies in the data were taken into account with linear mixed-model regression analysis, the increased- and decreased values for the patients were most prevalent for FTI at the heel, medial midfoot, hallux and other toes regions.

SIGNIFICANCE

In patients with painful Ledderhose disease, during walking, a shift of pressure was found towards the proximal and distal foot regions, while offloading the midfoot regions.

PROMIS Scores for Plantar Fasciitis Before and After Gastrocnemius Recession

BACKGROUND

There has been an established relationship between increased loading on the Achilles tendon and tension on the plantar fascia. This supports the idea that either tight gastrocnemius and soleus muscles or contractures of the Achilles tendon are risk factors for plantar fasciitis. Gastrocnemius recession has gained popularity as a viable surgical intervention for cases of chronic plantar fasciitis due to isolated gastrocnemius contracture. To our knowledge, this is the first study to investigate Patient-Reported Outcome Measurement Information Systems (PROMIS) scores in patients with plantar fasciitis before and after gastrocnemius recession.

METHODS

The Electronic Medical Record was queried for medical record numbers associated with Current Procedural Terminology code 27687 (gastrocnemius recession). Our study included all patients with a preoperative diagnosis of chronic plantar fasciitis with treatment via isolated gastrocnemius recession with 1-year minimum follow-up. Forty-one patients were included in our study. Patient variables were collected via chart review. Preoperative and postoperative PROMIS scores were collected in the clinic.

RESULTS

We followed up 41 patients with a median age of 48 years (interquartile range [IQR] 38-55) and median body mass index of 29.02 (IQR 29.02-38.74) for 1 year post surgery. Preoperative and postoperative PROMIS scores improved for physical function from 39.3 to 44.5 (P = .0005) and for pain interference from 62.8 to 56.5 (P = .0001). PROMIS depression scores were not significantly different (P = .6727). Visual analog scale (VAS) scores significantly decreased from 7.05 to 1.71 (P < .0001).

CONCLUSION

In this case series, we found the gastrocnemius recession to be an effective option for patients with refractory pain in plantar fasciitis. Our PROMIS and VAS data confirm this procedure's utility and highlight its ability to significantly decrease pain and improve physical function in patients with chronic plantar fasciitis, although final median scores did not reach normative standards for the population, suggesting some residual pain and/or dysfunction was, on average, present. Based on the results of this study, the authors conclude that gastrocnemius recession is a reasonable treatment option for chronic plantar fasciitis patients who fail nonoperative management.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Effects of Midsole Hardness on the Mechanical Response Characteristics of the Plantar Fascia during Running

High long-term stress on the plantar fascia (PF) is the main cause of plantar fasciitis. Changes in the midsole hardness (MH) of running shoes are an important factor leading to the alteration of the PF. This study aims to establish a finite-element (FE) model of the foot-shoe, and investigates the effects of midsole hardness on PF stress and strain. The FE foot-shoe model was built in ANSYS using computed-tomography imaging data. Static structural analysis was used to simulate the moment of running push and stretch. Plantar stress and strain under different MH levels were quantitatively analyzed. A complete and valid 3D FE model was established. With an increase in MH from 10 to 50 Shore A, the overall stress and strain of the PF were decreased by approximately 1.62%, and the metatarsophalangeal (MTP) joint flexion angle was decreased by approximately 26.2%. The height of the arch descent decreased by approximately 24.7%, but the peak pressure of the outsole increased by approximately 26.6%. The established model in this study was effective. For running shoes, increasing the MH reduces the stress and strain of PF, but also imposes a higher load on the foot.

Foot shape is related to load-induced shape deformations, but neither are good predictors of plantar soft tissue stiffness

Modern human feet are considered unique among primates in their capacity to transmit propulsive forces and re-use elastic energy. Considered central to both these capabilities are their arched configuration and the plantar aponeurosis (PA). However, recent evidence has shown that their interactions are not as simple as proposed by the theoretical and mechanical models that established their significance. Using three-dimensional foot scans and statistical shape and deformation modelling, we show that the shape of the longitudinal and transverse arches varies widely among the healthy adult population, and that the former is subject to load-induced arch flattening, whereas the latter is not. However, longitudinal arch shape and flattening are only one of the various foot shape-deformation relationships. PA stiffness was also found to vary widely. Yet only a small amount of this variability (approx. 10-18%) was explained by variations in foot shape, deformation and their combination. These findings add to the mounting evidence showing that foot mechanics are complex and cannot be accurately represented by simple models. Especially the interactions between longitudinal arch and PA appear to be far less constrained than originally proposed, most likely due to the many degrees of freedom provided by the structural complexity of our feet.

Achilles tendinopathy and plantar fasciopathy: Are we ignoring calcaneal bone morphology? - A radiological assessment of calcaneal parameters

BACKGROUND

A radiological study was conducted to determine whether calcaneal morphological differences contribute to the pathophysiology of Achilles tendinopathy and plantar fasciopathy. This study is aimed to support our new hypothesis to explain the pathophysiology leading to recalcitrant disease and also to identify the role of calcaneal osteotomy for treating these conditions.

MATERIALS AND METHODS

Calcaneal width and height distance deviation from centre of ankle joint rotation was measured on standardised lateral weight bearing Ankle radiographs. A comparison was made between control group and study group to identify the differences in measured parameters.

RESULTS

Significant difference (P = 0.05) was observed in calcaneal width distance in study group with Achilles tendinopathy. In Plantar fasciopathy the vertical distance was reduced suggesting flattening of arch in study group. However, the difference was not statistically significant.

CONCLUSION

The study identifies the importance of evaluating calcaneal morphology for patients with recalcitrant Achilles tendinopathy and plantar fasciopathy. A new hypothesis is proposed to explain the high stresses produced in entire Achilles -calcaneus -plantar fascia unit which leads to chronic inflammatory response and intra substance degeneration.

Impact of Sex and Velocity on Plantar Pressure Distribution during Gait: A Cross-Sectional Study Using an Instrumented Pressure-Sensitive Walkway

In-shoe systems and pressure plates are used to assess plantar pressure during gait, but additional tools are employed to evaluate other gait parameters. The GAITRite® system is a clinical gait evaluation tool. Extensive literature is available for spatiotemporal parameters, but it is scarce for relative plantar pressure data. Therefore, we investigated whether, when controlling for age, the GAITRite® system is able to distinguish the effects of walking velocity on plantar pressure parameters in six plantar regions in a large sample of adults. Participants (83 women and 87 men, aged 18−85 years) walked at three self-selected velocities (slow, preferred, fast) on a 6-m long GAITRite® walkway. Relative peak pressure, pressure-time integral, peak time and contact area were computed for six zones (lateral and medial heel, mid- and forefoot). The impact of age (covariate), sex, side, velocity, pressure zone and their interactions on pressure variables was evaluated. Velocity affected peak pressure, pressure-time integral, peak time and contact area (p < 0.001). With increasing self-selected gait velocity, medial forefoot peak pressure and pressure-time integral increased (p < 0.001), while heel and lateral forefoot regions displayed a nonlinear plantar pressure evolution. These results suggest lower (heel strike) or more equally distributed (push-off) loads at preferred gait velocity.

Surgical or non-surgical treatment of plantar fasciopathy (SOFT): study protocol for a randomized controlled trial

Background

Plantar fasciopathy is the most common reason for complaints of plantar heel pain and one of the most prevalent musculoskeletal conditions with a reported lifetime incidence of 10%. The condition is normally considered self-limiting with persistent symptoms that often last for several months or years. Multiple treatments are available, but no single treatment appears superior to the others. Heavy-slow resistance training and radiofrequency microtenotomy for the treatment of plantar fasciopathy have shown potentially positive effects on short- and long-term outcomes (> 3 months). However, the effect of heavy-slow resistance training compared with a radiofrequency microtenotomy treatment is currently unknown. This trial compares the efficacy of heavy-slow resistance training and radiofrequency microtenotomy treatment with supplemental standardized patient education and heel inserts in improving the Foot Health Status Questionnaire pain score after 6 months in patients with plantar fasciopathy.

Methods

In this randomized superiority trial, we will recruit 70 patients with ultrasound-confirmed plantar fasciopathy and randomly allocate them to one of two groups: (1) heavy-slow resistance training, patient education and a heel insert (n = 35), and (2) radiofrequency microtenotomy treatment, patient education and a heel insert (n = 35). All participants will be followed for 1 year, with the 6-month follow-up considered the primary endpoint. The primary outcome is the Foot Health Status Questionnaire pain domain score. Secondary outcomes include the remaining three domains of the Foot Health Status Questionnaire, a Global Perceived Effect scale, the physical activity level, and Patient Acceptable Symptom State, which is the point at which participants feel no further need for treatment.

Discussion

By comparing the two treatment options, we should be able to answer if radiofrequency microtenotomy compared with heavy-slow resistance training is superior in patients with plantar fasciopathy.

Trial registration

ClinicalTrials.gov NCT03854682. Prospectively registered on February 26, 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06785-w.

Foot arch rigidity in walking: In vivo evidence for the contribution of metatarsophalangeal joint dorsiflexion

Human foot rigidity is thought to provide a more effective lever with which to push against the ground. Tension of the plantar aponeurosis (PA) with increased metatarsophalangeal (MTP) joint dorsiflexion (i.e., the windlass mechanism) has been credited with providing some of this rigidity. However, there is growing debate on whether MTP joint dorsiflexion indeed increases arch rigidity. Further, the arch can be made more rigid independent of additional MTP joint dorsiflexion (e.g., when walking with added mass). The purpose of the present study was therefore to compare the influence of increased MTP joint dorsiflexion with the influence of added mass on the quasi-stiffness of the midtarsal joint in walking. Participants walked with a rounded wedge under their toes to increase MTP joint dorsiflexion in the toe-wedge condition, and wore a weighted vest with 15% of their body mass in the added mass condition. Plantar aponeurosis behavior, foot joint energetics, and midtarsal joint quasi-stiffness were compared between conditions to analyze the mechanisms and effects of arch rigidity differences. Midtarsal joint quasi-stiffness was increased in the toe-wedge and added mass conditions compared with the control condition (both p < 0.001). In the toe-wedge condition, the time-series profiles of MTP joint dorsiflexion and PA strain and force were increased throughout mid-stance (p < 0.001). When walking with added mass, the time-series profile of force in the PA did not increase compared with the control condition although quasi-stiffness did, supporting previous evidence that the rigidity of the foot can be actively modulated. Finally, more mechanical power was absorbed (p = 0.006) and negative work was performed (p < 0.001) by structures distal to the rearfoot in the toe-wedge condition, a condition which displayed increased midtarsal joint quasi-stiffness. This indicates that a more rigid foot may not necessarily transfer power to the ground more efficiently.

Radiofrequency Plantar Fascia Coblation With and Without Gastrocnemius Recession in the Management of Recalcitrant Plantar Fasciitis

BACKGROUND

Plantar fasciitis is the most common cause of plantar heel pain. Although most are self-limiting, recalcitrant conditions can be debilitating, significantly reducing patient's quality of life. A myriad of surgical procedures are available for the treatment of recalcitrant plantar fasciitis (RPF) with little consensus on best practice. This purpose of this study was to assess the efficacy of radiofrequency coblation with and without gastrocnemius release on the surgical management of RPF.

METHODS

Between June 2013 and June 2019, a total of 128 patients with RPF and tight gastrocnemius were treated surgically. Presence of tight gastrocnemius was assessed clinically by a positive Silfverskiold test. Group A (n = 73) consisted of patients who underwent radiofrequency coblation alone; group B (n = 55) consisted of patients who underwent radiofrequency coblation and endoscopic gastrocnemius recession. The primary outcome measure was visual analog scale (VAS) score. Secondary outcome measures included (1) American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score; (2) physical (PCS) and mental component summaries (MCS) of the 36-Item Short Form Health Survey; (3) overall assessment of improvement, expectation fulfilment, and satisfaction; and (4) complication rates.

RESULTS

Both groups reported significant improvement in VAS, AOFAS, and PCS scores postoperatively at 6 and 24 months. Group B (radiofrequency coblation with gastrocnemius recession) was associated with better VAS at both 6 months (3.0 ± 2.9 vs 1.7 ± 2.6, P < .05) and 24 months postoperatively (1.9 ± 3.1 vs 0.8 ± 2.0, P < .05) compared with group A (radiofrequency coblation without gastrocnemius recession). At 24 months postoperatively, no differences were found in AOFAS, PCS, MCS scores, expectation fulfilment, or overall satisfaction. No wound complications were reported in either group. One patient (group B) has persistent symptoms consistent with tarsal tunnel syndrome.

CONCLUSION

In this retrospective cohort comparative study, treatment of RPF with radiofrequency coblation alone was associated with slightly inferior results than radiofrequency coblation combined with endoscopic gastrocnemius recession in terms of pain relief without an increase in complication rates. However, at 2 years, we did not find a significant difference in other measures of outcome.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

The mechanical role of the metatarsophalangeal joint in human jumping

This study investigated the mechanical role of metatarsophalangeal (MTP) joints in human jumping. Eighteen healthy young men performed three types of single-leg jumps (SJ: squat jump; CMJ: countermovement jump; HJ: standing horizontal jump) on a force plate under barefoot (BARE) and forefoot immobilisation (FFIM) conditions. For FFIM, the forefoot was immobilised around the MTP joints of the dominant leg by a custom-made splint. Force-time components and the centre of pressure (COP) trajectory were measured from the ground reaction force (GRF) in the take-off phase of jumping. The vertical jump heights calculated from the net vertical impulse were lower under FFIM than under BARE during the CMJ (p < 0.05). The HJ distance under FFIM was significantly shorter than that under BARE (p < 0.01). The relative net vertical impulse was lower under FFIM than under BARE during the CMJ (p < 0.05). During the HJ, all the horizontal GRF variables were significantly lower under FFIM than under BARE (p < 0.01), but none of the vertical GRF variables differed between the two conditions. The horizontal relative GRF in the 90–95% of the final take-off phase during the HJ was significantly lower under FFIM than under BARE (p < 0.01). Under FFIM, the COP range in the antero-posterior direction in the take-off phase of the HJ decreased (p < 0.05), whereas its range in the anterior direction for the SJ and CMJ increased (p < 0.05). The results of this study indicate that MTP joint motion can play an important role in regulating force-generating capacities of toe flexor muscles in the take-off phase of human jumping, especially in the horizontal direction of horizontal jumping.

Young females with hallux valgus show lower foot joint movement stability compared to controls: An investigation of coordination patterns and variability

BACKGROUND

A kinematic coupling relationship exists between foot joints during gait. In individuals with hallux valgus, forefoot or hallux kinematics may be affected by adjacent or nonadjacent joint motion. Thus, this study aimed to investigate the foot joint coordination pattern and variability during gait in young females with hallux valgus.

METHODS

Twenty-five young females with hallux valgus and 25 healthy young females without hallux valgus were enrolled. Reflective markers were attached according to a multisegment foot model. Kinematic data were obtained using a three-dimensional motion analysis system. Joint angles between distal and proximal segments were calculated using analysis software. Foot joint coordination pattern and variability were assessed using a vector-coding technique.

FINDINGS

Individuals with hallux valgus had a larger rearfoot relative to shank eversion and forefoot relative to midfoot dorsiflexion during terminal stance and pre-swing compared with those without hallux valgus. There were no significant differences in coordination patterns, but the consistency of coordination between the rearfoot relative to shank motion in the frontal plane and forefoot relative to midfoot motion in the sagittal plane during terminal stance was greater in the hallux valgus group than in the control group.

INTERPRETATION

The soft tissue composing the first ray might suffer from more severe stress due to the large motion that occurred with low variability in individuals with hallux valgus. This finding may suggest that the altered kinematics and coordination variability in foot joints are related to hallux valgus biomechanical etiology.

Development and Clinical Evaluation of a Novel Foot Stretching Robot that Simultaneously Stretches Plantar Fascia and Achilles Tendon for Treatment of Plantar Fasciitis

OBJECTIVE

This paper presents the development and clinical evaluation of a foot stretching robot that simultaneously stretches the plantar fascia and Achilles tendon for the treatment of plantar fasciitis. The therapeutic effectiveness of the robot and feasibility of using metatarsophalangeal joint stiffness as an indicator of recovery were identified through the clinical evaluations.

METHODS

The robot implements an effective foot stretching protocol through a novel mechanism design that simultaneously stretches the plantar fascia and Achilles tendon using a single motor. Thirty patients with plantar fasciitis and fifteen healthy participants volunteered in the cross-sectional clinical evaluation, and nine patients from the patients group participated in the one-month clinical trial. Four main outcomes (Foot Function Index, Visual Analogue Scale-Foot and Ankle, plantar fascia thickness, and metatarsophalangeal joint stiffness) were used for the clinical evaluations.

RESULTS

In the cross-sectional clinical evaluation, the symptomatic feet of patients showed moderate negative correlation between normalized metatarsophalangeal joint stiffness and plantar fascia thickness with statistical significance. In the one-month clinical trial, all the main outcomes showed significant improvement after using the developed robot. Comparing our results with previous studies also indicated a therapeutic superiority of our robot for treating plantar fasciitis.

CONCLUSION

Our foot stretching robot had significant therapeutic effect on plantar fasciitis, and normalized metatarsophalangeal joint stiffness measured by our robot could be used as a monitoring indicator for recovery from plantar fasciitis.

SIGNIFICANCE

This study contributed to practical issues related to treatment of plantar fasciitis, and our results could be applied to effective treatment of plantar fasciitis and progressive monitoring of recovery.

Relationships between Plantar Pressure Distribution and Rearfoot Alignment in the Taiwanese College Athletes with Plantar Fasciopathy during Static Standing and Walking

BACKGROUND

Plantar fasciopathy (PF) is usually related to changes in foot arch, foot shape and rearfoot posture. However, little research has been implemented by using large-scale datasets, and even less has been conducted centering on plantar pressure distributions (PPDs) of different genders of PF athletes. This study aimed to investigate the relationships among the arch index (AI), the PPDs and the rearfoot postural alignment in hundreds of college athletes with PF during static standing and walking.

METHODS

Cross-sectional study of 100 male and 102 female athletes with PF was undertaken. The PF athletes' pain assessment and self-reported health status were examined for evaluating their musculoskeletal painful areas.

RESULTS

The PF athletes' PPDs mainly concentrated on inner feet in static standing, and transferred to lateral forefeet during the midstance phase of walking. The males' PPDs from the static standing to the midstance phase of walking mainly transferred to anterolateral feet. The females' PPDs mainly transferred to posterolateral feet. The PF athletes' static rearfoot alignment matched the valgus posture pattern. The medial band of plantar fascia and calcaneus were the common musculoskeletal pain areas.

CONCLUSIONS

Characteristics of higher plantar loads beneath medial feet associated with rearfoot valgus in bipedal static stance could be the traceable features for PF-related foot diagrams. Higher plantar loads mainly exerted on the lateral forefoot during the midstance phase of walking, and specifically concentrated on outer feet during the transition from static to dynamic state. Pain profiles seem to echo PPDs, which could function as the traceable beginning for the possible link among pronated low-arched feet, PF, metatarsalgia, calcanitis and Achilles tendinitis.

Comparison of Alternative Methods to Improve Weight-Bearing Sagittal Plane Anterior Leg Rotation

ABSTRACT

vonGaza, GL, and Chiu, LZF. Comparison of alternative methods to improve weight-bearing sagittal plane anterior leg rotation. J Strength Cond Res 35(12): 3315-3321, 2021-Promoting rearfoot plantar flexion may permit greater sagittal plane anterior leg rotation in weight-bearing tasks. Anterior leg rotation, where the proximal tibia translates forward, is required for tasks such as squatting and landing from a jump. Twenty-eight individuals with less than 25° anterior leg rotation during a weight-bearing lunge test were enrolled and randomly assigned to self-massage and stretching only (n = 15; 14 subjects retained) or self-massage and stretching plus gastrocnemius exercise (n = 13). Anterior leg rotation was assessed during a weight-bearing lunge test and a partial squat; 95% confidence interval (95% CI) of the change score and Cohen's d effect size were calculated. Anterior leg rotation in the weight-bearing lunge increased in the self-massage and stretching only (left: 95% CI [2.1°-5.4°], d = 1.14; right: 95% CI [2.3°-6.0°], d = 1.22) and self-massage and stretching plus gastrocnemius exercise (left: 95% CI [2.3°-7.5°], d = 1.71; right: 95% CI [4.2°-8.6°], d = 1.48) groups. There were no changes in anterior leg rotation in the partial squat for self-massage and stretching only (left: 95% CI [-1.2° to 2.5°], d = 0.15; right: 95% CI [-0.5° to 2.6°], d = 0.24) or self-massage and stretching plus gastrocnemius exercise (left: 95% CI [-0.2° to 4.8°], d = 0.55; right: 95% CI [-0.2° to 4.0°], d = 0.59) groups. Increases in anterior leg rotation in the weight-bearing lunge may be due to decreased passive stiffness in the plantar structures.

Midfoot and Ankle Mechanics in Block and Incline Heel Raise Exercises

ABSTRACT

Chiu, LZF and Dæhlin, TE. Midfoot and ankle mechanics in block and incline heel raise exercises. J Strength Cond Res 35(12): 3308-3314, 2021-Although the heel raise exercise is performed to strengthen the calf muscles, the combination of calf muscle and ground reaction forces elicits moments that may deform the foot's longitudinal arch. The primary purpose of this investigation was to examine whether the foot muscles contribute to supporting the longitudinal arch during heel raises. The secondary purpose was to compare foot and ankle mechanical efforts between traditional block vs. 22° incline heel raises. Six women and 6 men performed heel raises with body mass plus a barbell loaded with 40% (BM + 40%) and 60% (BM + 60%) of their body mass. Three-dimensional motion analysis and force platform data were collected. The midfoot joint was evaluated from the angle between the forefoot and rearfoot (i.e., arch angle) and net joint moment, which may elevate or reduce the arch height. Midfoot joint arch elevator moment seemed to be greater for BM + 60% than BM + 40% (p < 0.05; Cohen's d = 1.24-1.61), with minimal change in arch angle (p < 0.05; Cohen's d = 0.15-0.19). Midfoot joint arch elevator and ankle plantar flexor moments seemed to be greater in incline vs. block heel raises for both loads (p < 0.05; Cohen's d = 0.58-0.67). The increase in midfoot joint arch elevator moment with trivial change in arch angle supports the hypothesis that the foot muscles contribute to longitudinal arch support during heel raises. Performing incline heel raises may be hypothesized to be more effective to stimulate foot and calf muscle adaptations than block heel raises.

Deformable foot orthoses redistribute power from the ankle to the distal foot during walking

Recently, carbon fiber plates, or orthoses, have been incorporated into footwear to improve running performance, presumably through improved energy storage and return. However, few studies have explored the energetic effects these orthoses have on the distal foot, have utilized such orthoses in walking, and none have sought to specifically harness metatarsophalangeal joint deformation to store and return energy to the ankle-foot complex. To address these gaps, we developed and tested a deformable carbon fiber foot orthosis aiming to harness foot energetics and quantify the resulting effects on ankle energetics during walking in healthy adults. Eight subjects walked under three conditions: barefoot (BF), with minimalist shoes (SH), and with bilateral, deformable foot orthoses in the minimalist shoes (ORTH). Ankle and distal foot energetics, foot-to-floor and ankle angle, stance time, step length, and max center of pressure (COP) position were calculated. When walking with the orthoses, subjects showed 263.6% increase in positive distal foot work along with a 31.9% decrease in ankle work and little to no change in the overall ankle-foot complex work. Step length, stance time, and max anterior COP position significantly increased with orthosis use. No statistical or visual differences were found between BF and SH conditions indicating that our findings were due to the foot orthoses. These results suggest this foot orthosis redistributes power from the ankle to the distal foot for healthy adults, reducing the energetic demand on the ankle. These results lay the foundation for designing orthotics and footwear to improve ankle-foot energetics for clinical populations.

Does the Calcaneus Serve as Hypomochlion within the Lower Limb by a Myofascial Connection?-A Systematic Review

(1) Background: Clinical approaches have depicted interconnectivity between the Achilles tendon and the plantar fascia. This concept has been applied in rehabilitation, prevention, and in conservative management plans, yet potential anatomical and histological connection is not fully understood. (2) Objective: To explore the possible explanation that the calcaneus acts as a hypomochlion. (3) Methods: 2 databases (Pubmed and Livivo) were searched and studies, including those that examined the relationship of the calcaneus to the Achilles tendon and plantar fascia and its biomechanical role. The included studies highlighted either the anatomical, histological, or biomechanical aspect of the lower limb. (4) Results: Seventeen studies were included. Some studies depicted an anatomical connection that slowly declines with age. Others mention a histological similarity and continuity via the paratenon, while a few papers have brought forward mechanical reasoning. (5) Conclusion: The concept of the calcaneus acting as a fulcrum in the lower limb can partially be supported by anatomical, histological, and biomechanical concepts. Despite the plethora of research, a comprehensive understanding is yet to be investigated. Further research exploring the precise interaction is necessary.

Association of Ankle Dorsiflexion With Plantar Fasciitis

This study aimed to compare the mean ankle dorsiflexion range between individuals with and without plantar fasciitis using passive ankle dorsiflexion with consistent pressure, and to identify the prevalence of an isolated gastrocnemius and gastrocnemius soleus complex contracture in 2 groups. 91 participants were prospectively classified into the plantar fasciitis group (45 subjects) and the control group (46 subjects). Ankle dorsiflexion was measured with the knee extended and with the knee flexed 90° using a standard orthopedic goniometer while a consistent force of 2 kg was applied under the plantar surface of the forefoot using a custom-made scale. Intraclass correlation coefficients (ICC) were calculated to determine the interobserver and intraobserver reliability of the current ankle dorsiflexion measurement. The current ankle dorsiflexion measurement revealed excellent interobserver and intraobserver reliability. The mean ankle dorsiflexion in the knee extended was -9.6° ± 8.1° and -11.2° ± 8.2° in the study and control groups, respectively (p = .353). The mean ankle dorsiflexion in the knee flexed was 7.8° ± 6.5° and 5.1° ± 7.4° in the study and control groups, respectively (p = .068). In the study and control groups, 68.9% and 65.2%, respectively, had an isolated gastrocnemius contracture and 24.4% and 30.4%, respectively, had a gastrocnemius-soleus complex contracture (p = .768). The present study demonstrated that there were no significant differences in passive ankle dorsiflexion and in the prevalence of an isolated gastrocnemius or gastrocnemius soleus complex contracture between individuals with and without plantar fasciitis.

The Subtle Cavovarus Foot Deformity: The Nonneurologic Form of Cavus Foot Deformity

Conditions of ankle instability, peroneal tendon tears, and stress fractures of the lateral metatarsals are commonly encountered in a clinical foot and ankle practice. Evaluation of the supporting foot structure is critical to prevent failure of index procedures. The prominence of the subtle cavus foot is now a recognized entity and must be properly diagnosed and addressed surgically.

Elasticity of the Achilles Tendon in Individuals With and Without Plantar Fasciitis: A Shear Wave Elastography Study

The elastic properties of the Achilles tendon (AT) are altered in local injury or other diseases and in response to changes in mechanical load. Recently, elastography has been used to evaluate variations in tendon elastic properties, mainly among healthy individuals or athletes. Therefore, this study evaluated the biomechanical changes in ATs in individuals with and without plantar fasciitis (PF). The purposes were as follows: (1) to evaluate the passive stiffness of three regions of the AT which defined as 0 (AT0 cm), 3 (AT3 cm), and 6 cm (AT6 cm) above the calcaneal tuberosity in participants with and without PF, (2) to investigate the interplay between the passive stiffness in patients with PF and pain, (3) to detect optimal cut-off points of stiffness of the AT in assessing individuals with chronic PF, and (4) to determine the correlation between the plantar fascia thickness (PFT) and pain. This cross-sectional study included 40 participants (mean age = 51 ± 13 years). When the ankle was in a relaxed position, patients with PF experienced increased passive stiffness in AT0 cm (p = 0.006) and AT3 cm (P = 0.003), but not in the neutral position. Significant correlations were observed between pain and stiffness of AT (AT0 cm r = 0.489, P = 0.029; AT3 cm r = 487, P = 0.030; AT6 cm r = 0.471, P = 0.036), but not in the PFT (P = 0.557). Optimal cut-off stiffness was AT (452 kPa) in the relaxed ankle position. The plantar fascia of patients with PF was significantly thicker than that of the controls (P < 0.001). Findings from the present study demonstrate that tendon stiffness is a good indicator of the clinical situation of patients with PF. Monitoring passive tendon stiffness may provide additional information to assess severity of the condition and guide therapeutic. The treatment programs for PF should also be tailored to the distal AT, as conventional therapy might not be targeted to tight tendons.

Effects of age and locomotor demand on foot mechanics during walking

Older adults exhibit reductions in push-off power that are often attributed to deficits in plantarflexor force-generating capacity. However, growing evidence suggests that the foot may also contribute to push-off power during walking. Thus, age-related changes in foot structure and function may contribute to altered foot mechanics and ultimately reduced push-off power. The purpose of this paper was to quantify age-related differences in foot mechanical work during walking across a range of speeds and at a single fixed speed with varied demands for push-off power. 9 young and 10 older adults walked at 1.0, 1.2, and 1.4 m/s, and at 1.2 m/s with an aiding or impeding horizontal pulling force equal to 5% BW. We calculated foot work in Visual3D using a unified deformable foot model, accounting for contributions of structures distal to the hindfoot's center-of-mass. Older adults walked while performing less positive foot work and more negative net foot work (p < 0.05). Further, we found that the effect of age on mechanical work performed by the foot and the ankle-foot complex increased with increased locomotor demand (p < 0.05). Our findings suggest that during walking, age-related differences in foot mechanics may contribute to reduced push-off intensity via greater energy loss from distal foot structures, particularly during walking tasks with a greater demand for foot power generation. These findings are the first step in understanding the role of the foot in push-off power deficits in older adults and may serve as a roadmap for developing future low-cost mobility interventions.

The rise of the longitudinal arch when sitting, standing, and walking: Contributions of the windlass mechanism

The original windlass mechanism describes a one-to-one coupling between metatarsal joint dorsiflexion and medial longitudinal arch rise. The description assumes a sufficiently stiff plantar aponeurosis and absence of foot muscle activity. However, recent research calls for a broader interpretation of the windlass mechanism that accounts for an extensible plantar aponeurosis and active foot muscles. In this study, we investigate the rise of the arch in response to toe dorsiflexion when sitting, standing, and walking to discuss the windlass mechanism’s contributions in static and dynamic load scenarios. 3D motion analysis allowed a kinematic investigation of the rise and drop of the arch relative to the extent of toe dorsiflexion. The results suggest that static windlass effects poorly predict the relationship between arch dynamics and metatarsophalangeal joint motion during dynamic load scenarios, such as walking. We were able to show that toe dorsiflexion resulted in an immediate rise of the longitudinal arch during sitting and standing. In contrast, a decrease in arch height was observed during walking, despite toe dorsiflexion at the beginning of the push-off phase. Further, the longitudinal arch rose almost linearly with toe dorsiflexion in the static loading scenarios, while the dynamic load scenario revealed an exponential rise of the arch. In addition to that, the rate of change in arch height relative to toe motion was significantly lower when sitting and standing compared to walking. Finally, and most surprisingly, arch rise was found to correlate with toe dorsiflexion only in the dynamic loading scenario. These results challenge the traditional perspective of the windlass mechanism as the dominating source of foot rigidity for push-off against the ground during bipedal walking. It seems plausible that other mechanisms besides the windlass act to raise the foot arch.

On the morphological relations of the Achilles tendon and plantar fascia via the calcaneus: a cadaveric study

Current treatments of plantar fasciitis are based on the premise that the Achilles tendon (AT) and plantar fascia (PF) are mechanically directly linked, which is an area of debate. The aim of this study was to assess the morphological relationship between the AT and PF. Nineteen cadaveric feet were x-ray imaged, serially sectioned and plastinated for digital image analyses. Measurements of the AT and PF thicknesses and cross-sectional areas (CSA) were performed at their calcaneal insertion. The fiber continuity was histologically assessed in representative subsamples. Strong correlations exist between the CSA of the AT and PF at calcaneal insertion and the CSA of PF's insertional length (r = 0.80), and between the CSAs of AT's and PF's insertional lengths. Further correlations were observed between AT and PF thicknesses (r = 0.62). This close morphological relationship could, however, not be confirmed through x-ray nor complete fiber continuity in histology. This study provides evidence for a morphometric relationship between the AT and PF, which suggests the presence of a functional relationship between these two structures following the biological key idea that the structure determines the function. The observed morphological correlations substantiate the existing mechanical link between the AT and PF via the posterior calcaneus and might explain why calf stretches are a successful treatment option for plantar heel pain.

The extensibility of the plantar fascia influences the windlass mechanism during human running

The arch of the human foot is unique among hominins as it is compliant at ground contact but sufficiently stiff to enable push-off. These behaviours are partly facilitated by the ligamentous plantar fascia whose role is central to two mechanisms. The ideal windlass mechanism assumes that the plantar fascia has a nearly constant length to directly couple toe dorsiflexion with a change in arch shape. However, the plantar fascia also stretches and then shortens throughout gait as the arch-spring stores and releases elastic energy. We aimed to understand how the extensible plantar fascia could behave as an ideal windlass when it has been shown to strain throughout gait, potentially compromising the one-to-one coupling between toe arc length and arch length. We measured foot bone motion and plantar fascia elongation using high-speed X-ray during running. We discovered that toe plantarflexion delays plantar fascia stretching at foot strike, which probably modifies the distribution of the load through other arch tissues. Through a pure windlass effect in propulsion, a quasi-isometric plantar fascia's shortening is delayed to later in stance. The plantar fascia then shortens concurrently to the windlass mechanism, likely enhancing arch recoil at push-off.

The human foot functions like a spring of adjustable stiffness during running

Like other animals, humans use their legs like springs to save energy during running. One potential contributor to leg stiffness in humans is the longitudinal arch (LA) of the foot. Studies of cadaveric feet have demonstrated that the LA can function like a spring, but it is unknown whether humans can adjust LA stiffness in coordination with more proximal joints to help control leg stiffness during running. Here, we used 3D motion capture to record 27 adult participants running on a forceplate-instrumented treadmill, and calculated LA stiffness using beam bending and midfoot kinematics models of the foot. Because changing stride frequency causes humans to adjust overall leg stiffness, we had participants run at their preferred frequency and frequencies 35% above and 20% below preferred frequency to test for similar adjustments in the LA. Regardless of which foot model we used, we found that participants increased LA quasi-stiffness significantly between low and high frequency runs, mirroring changes at the ankle, knee and leg overall. However, among foot models, we found that the model incorporating triceps surae force into bending force on the foot produced unrealistically high LA work estimates, leading us to discourage this modeling approach. Additionally, we found that there was not a consistent correlation between LA height and quasi-stiffness values among the participants, indicating that static LA height measurements are not good predictors of dynamic function. Overall, our findings support the hypothesis that humans dynamically adjust LA stiffness during running in concert with other structures of the leg.

Finite element method based parametric study of Gastrocnemius-soleus recession: implications to the treatment of midfoot-forefoot overload syndrome

Gastrocnemius-soleus recession has been used to treat midfoot-forefoot overload syndrome and plantar fasciitis induced by equinus of the ankle joint. A controlled and selective amount of recession is imperative to maintain muscle strength and stability. The objective of this study was to conduct a parametric study to quantify the relationship between the level of recession and plantar fascia stress. A finite element model of the foot-ankle-shank complex was reconstructed from magnetic resonance and computed tomography images of a 63-year-old normal female. The model was validated by comparing modeled stresses to the measured plantar pressure distribution of the model participant during balanced standing. The midstance and push-off instants of walking stance were simulated with different levels and combinations of gastrocnemius-soleus recession resembled by different amounts of muscle forces. Halving the muscle forces at midstance reduced the average plantar fascia stress by a quarter while reducing two-third of the muscle forces at push-off reduced the average fascia stress by 18.2%. While the first ray of the plantar fascia experienced the largest stress among the five fasciae, the stress was reduced by 77.8% and 16.9% when the load was halved and reduced by two-third at midstance and push-off instants, respectively. Reduction in fascia stress implicates a lower risk of plantar fasciitis and other midfoot-forefoot overload syndromes. The outcome of this study can aid physicians to determine the amount of gastrocnemius-soleus recession towards patients with vdifferent levels of plantar fascia overstress. A detailed three-dimensional modelling on the plantar fascia is warranted in future study.

Human plantar fascial dimensions and shear wave velocity change in vivo as a function of ankle and metatarsophalangeal joint positions

The plantar fascia (PF), a primary contributor of the foot arch elasticity, may experience slack, taut, and stretched states depending on the ankle and metatarsophalangeal (MTP) joint positions. Since PF has proximodistal site difference in its dimensions and stiffness, the response to applied tension can also be site specific. Furthermore, PF can contribute to supporting the foot arch while being stretched beyond the slack length, but it has never been quantitatively evaluated in vivo. This study investigated the effects of the ankle and MTP joint positions on PF length and localized thickness and shear wave velocity (SWV) at three different sites from its proximal to distal end using magnetic resonance and supersonic shear imaging techniques. During passive ankle dorsiflexion, rise of SWV, an indication of slack length, was observed at the proximal site when the ankle was positioned by 10°-0° ankle plantar flexion with up to 3 mm (+1.5%) increase in PF length. On the other hand, SWV increased at the distal site when MTP joint dorsiflexed 40° with the ankle 30°-20° plantar flexion, and in this position, PF was lengthened up to 4 mm (+2.3%). Beyond the slack length, SWV curvilinearly increased at all measurement sites toward the maximal dorsiflexion angle whereas PF lengthened up to 9 mm (+7.6%) without measurable changes in its thickness. This study provides evidence that the dimensions and SWV of PF change in a site-specific manner depending on the ankle and MTP joint positions, which can diversify foot arch elasticity during human locomotion.NEW & NOTEWORTHY Joint angle dependence and site specificity of the plantar fascial dimensions and SWV were examined by combining sagittal magnetic resonance and supersonic shear imaging techniques. We revealed that the site-specific changes in PF SWV were related to joint angle positions, i.e., PF slackness and elasticity changed in varying combinations of ankle and MTP angle. Our findings suggest that PF can elastically support the foot arch throughout the stance phase of human bipedal locomotion.

Foot stiffening during the push-off phase of human walking is linked to active muscle contraction, and not the windlass mechanism

The rigidity of the human foot is often described as a feature of our evolution for upright walking and is bolstered by a thick plantar aponeurosis that connects the heel to the toes. Previous descriptions of human foot function consider stretch of the plantar aponeurosis via toe extension (windlass mechanism) to stiffen the foot as it is levered against the ground for push-off during walking. In this study, we applied controlled loading to human feet in vivo, and studied foot function during the push-off phase of walking, with the aim of carefully testing how the foot is tensioned during contact with the ground. Both experimental paradigms revealed that plantar aponeurosis strain via the 'windlass mechanism' could not explain the tensioning and stiffening of the foot that is observed with increased foot-ground contact forces and push-off effort. Instead, electromyographic recordings suggested that active contractions of ankle plantar flexors provide the source of tension in the plantar aponeurosis. Furthermore, plantar intrinsic foot muscles were also contributing to the developed tension along the plantar aspect of the foot. We conclude that active muscular contraction, not the passive windlass mechanism, is the foot's primary source of rigidity for push-off against the ground during bipedal walking.

The effectiveness of radial extracorporeal shock wave therapy (rESWT), sham-rESWT, standardised exercise programme or usual care for patients with plantar fasciopathy: study protocol for a double-blind, randomised, sham-controlled trial

Background

Plantar fasciopathy is a common cause of plantar heel pain, with a reported prevalence of up to 10%. The choice of best practice in these patients is debated. Two randomised studies reported that radial extracorporeal shock wave therapy is effective, but a meta-analysis concluded that due to methodological limitations, the evidence is questionable. There are few studies reporting the effect of exercise programs with high-load strength training, despite widespread use. The objective of this placebo-controlled, observer-blinded and partly patient blinded trial is to compare rESWT, sham-rESWT, standardised exercise programme and usual care for alleviating heel pain at 6 and 12 months follow-up.

Methods/design

A double-blind, randomised, sham-controlled trial is conducted at a hospital outpatient clinic of physical medicine and rehabilitation. Patients with chronic (> 3 months) pain due to plantar fasciopathy, aged 18 to 70 years old, are eligible for inclusion in the trial. Patients will be randomly allocated in 1:1 ratio to receive rESWT, sham-rESWT, standardised exercises or usual care. The sample size is estimated to 200 patients, 50 in each group. rESWT or sham-rESWT will be given once a week for 3 weeks. A physiotherapist will supervise the exercises, with a total of 8 sessions over 12 weeks. The patients in the usual care group will receive information, advice and foot orthosis only. All patients, regardless of group, will receive the same information and get an individual customised foot orthosis made by an orthopaedic technician. The primary outcome measure is heel pain intensity during activity in the last week, using a numeric rating scale (NRS, 0 to 10) at the 6 months follow-up adjusted for baseline pain intensity. The secondary outcomes are at the 6- and 12-month follow-up and include Foot Functional Index Revised Short Version (FFI-RS), Patient Global Impression of Change Scale (7-point Likert scale), RAND-12 Health Status Inventory (RAND-12), NRS during rest and NRS during activity (12 months). The patients receiving rESWT/sham-rESWT and the outcome assessor will be blinded to the group assignment.

Discussion

This trial is designed in order to provide results important for future clinical practice.

Trial registration

ClinicalTrials.gov NCT03472989. Registered on 14 March 2018

Influence of different knee and ankle ranges of motion on the elasticity of triceps surae muscles, Achilles tendon, and plantar fascia

Stiffness is a valuable indicator of the functional capabilities of muscle-tendon-fascia. Twenty healthy subjects participated in this study in which the passive elastic properties of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus muscles (SOL), Achilles tendon (AT, at 0 cm, 3 cm and 6 cm proximal to the calcaneus tubercle, corresponding to AT0cm, AT3cm and AT6cm, respectively) and plantar fascia (PF) were quantified when their knee was fully extended or flexed to 90° using shear wave elastography at 25° of dorsiflexion (DF25°), 0° (neutral position) of flexion, and 50° of plantar flexion (PF50°) of the ankle joint. The stiffnesses of the AT, MG, LG, SOL and the fascia with the knee fully extended were significantly higher than those with the knee flexed to 90° (p < 0.05), while the stiffness of the PF showed the opposite relationship (p < 0.05). When the knee was fully extended, the stiffness was higher in the LG than in the MG at PF50° and 0° (p < 0.01), and it was higher in the MG than in the LG at DF25° (p = 0.009). Nevertheless, regardless of the knee angle, the stiffness decreased from AT3cm > AT0cm > AT6cm at PF50° and 0° (p < 0.001), while the stiffness decreased from AT0cm > AT3cm > AT6cm at DF25°. Regardless of the knee and ankle angles, the stiffness of the PF increased in a proximal-to-distal direction (p < 0.001). These insights can be used to gain a more intuitive understanding of the relationships between the elastic properties of the muscle-tendon unit and its function.

Influence of different knee and ankle ranges of motion on the elasticity of triceps surae muscles, Achilles tendon, and plantar fascia

Stiffness is a valuable indicator of the functional capabilities of muscle-tendon-fascia. Twenty healthy subjects participated in this study in which the passive elastic properties of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus muscles (SOL), Achilles tendon (AT, at 0 cm, 3 cm and 6 cm proximal to the calcaneus tubercle, corresponding to AT0cm, AT3cm and AT6cm, respectively) and plantar fascia (PF) were quantified when their knee was fully extended or flexed to 90° using shear wave elastography at 25° of dorsiflexion (DF25°), 0° (neutral position) of flexion, and 50° of plantar flexion (PF50°) of the ankle joint. The stiffnesses of the AT, MG, LG, SOL and the fascia with the knee fully extended were significantly higher than those with the knee flexed to 90° (p < 0.05), while the stiffness of the PF showed the opposite relationship (p < 0.05). When the knee was fully extended, the stiffness was higher in the LG than in the MG at PF50° and 0° (p < 0.01), and it was higher in the MG than in the LG at DF25° (p = 0.009). Nevertheless, regardless of the knee angle, the stiffness decreased from AT3cm > AT0cm > AT6cm at PF50° and 0° (p < 0.001), while the stiffness decreased from AT0cm > AT3cm > AT6cm at DF25°. Regardless of the knee and ankle angles, the stiffness of the PF increased in a proximal-to-distal direction (p < 0.001). These insights can be used to gain a more intuitive understanding of the relationships between the elastic properties of the muscle-tendon unit and its function.

Influence of different knee and ankle ranges of motion on the elasticity of triceps surae muscles, Achilles tendon, and plantar fascia

Stiffness is a valuable indicator of the functional capabilities of muscle-tendon-fascia. Twenty healthy subjects participated in this study in which the passive elastic properties of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus muscles (SOL), Achilles tendon (AT, at 0 cm, 3 cm and 6 cm proximal to the calcaneus tubercle, corresponding to AT0cm, AT3cm and AT6cm, respectively) and plantar fascia (PF) were quantified when their knee was fully extended or flexed to 90° using shear wave elastography at 25° of dorsiflexion (DF25°), 0° (neutral position) of flexion, and 50° of plantar flexion (PF50°) of the ankle joint. The stiffnesses of the AT, MG, LG, SOL and the fascia with the knee fully extended were significantly higher than those with the knee flexed to 90° (p < 0.05), while the stiffness of the PF showed the opposite relationship (p < 0.05). When the knee was fully extended, the stiffness was higher in the LG than in the MG at PF50° and 0° (p < 0.01), and it was higher in the MG than in the LG at DF25° (p = 0.009). Nevertheless, regardless of the knee angle, the stiffness decreased from AT3cm > AT0cm > AT6cm at PF50° and 0° (p < 0.001), while the stiffness decreased from AT0cm > AT3cm > AT6cm at DF25°. Regardless of the knee and ankle angles, the stiffness of the PF increased in a proximal-to-distal direction (p < 0.001). These insights can be used to gain a more intuitive understanding of the relationships between the elastic properties of the muscle-tendon unit and its function.

Influence of different knee and ankle ranges of motion on the elasticity of triceps surae muscles, Achilles tendon, and plantar fascia

Stiffness is a valuable indicator of the functional capabilities of muscle-tendon-fascia. Twenty healthy subjects participated in this study in which the passive elastic properties of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus muscles (SOL), Achilles tendon (AT, at 0 cm, 3 cm and 6 cm proximal to the calcaneus tubercle, corresponding to AT0cm, AT3cm and AT6cm, respectively) and plantar fascia (PF) were quantified when their knee was fully extended or flexed to 90° using shear wave elastography at 25° of dorsiflexion (DF25°), 0° (neutral position) of flexion, and 50° of plantar flexion (PF50°) of the ankle joint. The stiffnesses of the AT, MG, LG, SOL and the fascia with the knee fully extended were significantly higher than those with the knee flexed to 90° (p < 0.05), while the stiffness of the PF showed the opposite relationship (p < 0.05). When the knee was fully extended, the stiffness was higher in the LG than in the MG at PF50° and 0° (p < 0.01), and it was higher in the MG than in the LG at DF25° (p = 0.009). Nevertheless, regardless of the knee angle, the stiffness decreased from AT3cm > AT0cm > AT6cm at PF50° and 0° (p < 0.001), while the stiffness decreased from AT0cm > AT3cm > AT6cm at DF25°. Regardless of the knee and ankle angles, the stiffness of the PF increased in a proximal-to-distal direction (p < 0.001). These insights can be used to gain a more intuitive understanding of the relationships between the elastic properties of the muscle-tendon unit and its function.

Foot flexibility confounds the assessment of triceps surae extensibility in children with spastic paresis during typical physical examinations

Accurate assessment of the talo-crural (ankle) joint angle at physical examination is important for assessing extensibility of m. triceps surae (TS) in children with spastic cerebral paresis (SCP). The main aim of this study was to quantify foot flexibility during standardized measurements of TS muscle-tendon complex extensibility (i.e. based on foot-sole rotation) in SCP children, and typical developed (TD) ones. Additionally, we aim to define a method that minimizes the confounding effects of foot flexibility on estimates of talo-crural joint angles and TS extensibility. Children, aged 6-13 years, with SCP (GMFCS I-III, n = 13) and TD children (n = 14) participated in this study. Externally applied -1 Nm, 0 Nm, 1 Nm and 4 Nm dorsal flexion foot plate moments were imposed. Resulting TS origin-insertion lengths, foot sole (φ_FoSo) rotations, and changes in talo-crural joint angle (φ_TaCr) were measured. Foot flexibility was quantified as Δ(φ_TaCr -φ_FoSo) between the 0 Nm and 4 Nm dorsal flexion conditions. In both groups, φ_FoSo rotations of approximately 20° were observed between 0 Nm and 4 Nm dorsal flexion, of which about 6° (≈30%) was related to foot flexibility. Foot flexibility correlated to φ_FoSo (r = 0.69) but not to φ_TaCr (r = 0.11). For φ_FoSo no significant differences were found between groups at 4 Nm. However, for SCP children the mean estimate of φ_TaCr was 4.3° more towards plantar flexion compared to the TD group (p < 0.05). Normalized TS lengths show a higher coefficient of correlation with φ_TaCr (r² = 0.82) than with φ_FoSo (r² = 0.60), indicating that TS lengths are better estimated by talo-cural joint angles. In both SCP and TD children aged 6-13 year, estimates of TS length and extensibility based on foot sole assessments are confounded by foot flexibility. Assessments of TS extensibility at physical examination will be more accurate when based on measurements of talo-crural joint angles.

Endoscopic plantar fasciotomy for plantar fasciitis: A systematic review and network meta-analysis of the English literature

BACKGROUND

Currently, there is limited evidence on outcomes for endoscopic plantar fasciotomy.

OBJECTIVES

An evidence-based literature review for outcomes of endoscopic plantar fasciotomy for the treatment of plantar fasciitis is provided.

METHODS

A comprehensive evidence-based literature review of PubMed and Cochrane databases was conducted on 9th March 2019, which identified 12 relevant articles assessing the efficacy of endoscopic plantar fasciotomy. The studies were then assigned to a level of evidence (I-IV). Individual studies were reviewed to provide a grade of recommendation (A-C, I) according to the Wright classification in support of or against endoscopic plantar fascia release.

RESULTS

Based on the results of this evidence-based review, there is poor evidence (grade C) to support endoscopic plantar fascia release. Release of the medial 2/3 of the plantar fascia in endoscopic plantar fasciotomy was associated with higher AOFAS score.

CONCLUSION

Although the majority of the level of evidence was low (level IV) and grade of recommendation was poor (grade C), there seemed to be good outcomes for endoscopic plantar fasciotomy. There is a need for more high quality level I randomized controlled trials with validated outcome measures to allow for stronger recommendations to be made.

Effectiveness of Mechanical Treatment for Plantar Fasciitis: A Systematic Review

CONTEXT

Plantar fasciitis is one of the most common foot injuries. Several mechanical treatment options, including shoe inserts, ankle-foot orthoses, tape, and shoes are used to relieve the symptoms of plantar fasciitis.

OBJECTIVES

To investigate the effectiveness of mechanical treatment in the management of plantar fasciitis.

EVIDENCE ACQUISITION

The review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. A systematic search was performed in PubMed, CINAHL, Embase, and Cochrane up to March 8, 2018. Two independent reviewers screened eligible articles and assessed risk of bias using the Cochrane Collaboration's risk of bias tool.

EVIDENCE SYNTHESIS

A total of 43 articles were included in the study, evaluating 2837 patients. Comparisons were made between no treatment and treatment with insoles, tape, ankle-foot orthoses including night splints and shoes. Tape, ankle-foot orthoses, and shoes were also compared with insoles. Follow-up ranged from 3 to 5 days to 12 months. Cointerventions were present in 26 studies.

CONCLUSIONS

Mechanical treatment can be beneficial in relieving symptoms related to plantar fasciitis. Contoured full-length insoles are more effective in relieving symptoms related to plantar fasciitis than heel cups. Combining night splints or rocker shoes with insoles enhances improvement in pain relief and function compared with rocker shoes, night splints, or insoles alone. Taping is an effective short-term treatment. Future studies should aim to improve methodological quality using blinding, allocation concealment, avoid cointerventions, and use biomechanical measures of treatment effects.

Influence of the windlass mechanism on arch-spring mechanics during dynamic foot arch deformation

The function of the human foot is described dichotomously as a compliant structure during mid-stance and a stiff lever during push-off. The arch-spring and the windlass mechanisms, respectively, describe each of these behaviours; however, their interaction has not been quantified to date. We hypothesized that by engaging the windlass mechanism with metatarsophalangeal joint (MTPJ) dorsiflexion, we would observe stiffening of the arch and reduced energy absorption and dissipation during dynamic compressions of the foot. Using a custom apparatus, the MTPJ angle was fixed at 30 degrees of plantarflexion, neutral or 30 degrees of dorsiflexion for nine participants, with the shank positioned similarly to the end of mid-stance. The arch was compressed at two speeds, with the faster speed comparable to walking around 1.5 m s^-1 Six cameras captured the compression and elongation of the arch, along with other kinematic variables, synchronously with the ground reaction force. Combining these measures, we computed the energy absorbed, returned and dissipated in the arch. Contrary to our hypothesis, when the windlass mechanism was engaged, the arch elongated more, and absorbed and dissipated more energy than when it was not engaged. This engagement of the windlass altered the rotational axis of the mid-foot, which probably oriented the arch-spanning structures closer to their resting length, increasing their compliance. This study provides novel evidence for an interplay between the windlass and arch-spring mechanisms that aids in regulation of energy storage within the foot.

Biomechanical effects of rocker shoes on plantar aponeurosis strain in patients with plantar fasciitis and healthy controls

Plantar fasciitis is a frequently occurring overuse injury of the foot. Shoes with a stiff rocker profile are a commonly prescribed treatment modality used to alleviate complaints associated with plantar fasciitis. In rocker shoes the apex position was moved proximally as compared to normal shoes, limiting the progression of the ground reaction forces (GRF) and peak plantarflexion moments during gait. A stiff sole minimizes dorsiflexion of the toes. The aim of this study was to investigate whether the biomechanical effects of rocker shoes lead to minimization of plantar aponeurosis (PA) strain during gait in patients with plantar fasciitis and in healthy young adults. 8 patients with plantar fasciitis (1 male, 7 females; mean age 55.0 ± 8.4 years) and 8 healthy young adults (8 females; mean age 24.1 ± 1.6 years) participated in the study. Each participant walked for 1 minute on an instrumented treadmill while wearing consecutively in random order shoes with a normal apex position (61.2 ± 2.8% apex) with flexible insole (FN), normal apex position with stiff insole (SN), proximal apex position (56.1 ± 2.6% apex) with flexible insole (FR) and proximal apex position with stiff insole (SR). Marker position data of the foot and lower leg and GRF were recorded. An OpenSim foot model was used to compute the change in PA length based on changes in foot segment positions during gait. The changes in PA length due to increases in Achilles tendon forces were computed based on previous data of a cadaver study. PA strain computed from both methods was not statistically different between shoe conditions. Peak Achilles tendon force, peak first metatarsophalangeal (MTP1) joint angle and peak plantarflexion moment were significantly lower when walking with the rocker shoe with a proximal apex position and a stiff insole for all subjects (p<.05). Changes in Achilles tendon forces during gait accounted for 65 ± 2% of the total PA strain. Rocker shoes with a stiff insole reduce peak dorsiflexion angles of the toes and plantar flexion moments, but not PA strain because the effects of a proximal apex position and stiff insole do not occur at the same time, but independently affect PA strain at 80-90% and 90-100% of the stance phase. Rocker shoes with an apex position of ~56% are insufficient to significantly reduce peak PA strain values in patients with plantar fasciitis and healthy young adults.

Properties and Function of the Flexor Hallucis Capsularis Interphalangeus Tendon

INTRODUCTION

The fibrocartilagenous plantar plates of the forefoot are biomechanically important, forming the primary distal attachment for the plantar aponeurosis. They are integral to the function of the windlass mechanism in supporting the arches of the foot in gait. Dissection of the cadaveric hallux revealed an organised sagittal thickening of the dorsal side of the flexor hallucis longus (FHL) sheath, which attached the interphalangeal plantar plate to the metatarsophalangeal (MTP) plantar plate. A description of a similar structure was made in 1984 when it was termed the flexor hallucis capsularis interphalangeus (FHCI) - however, it has not been researched since, and we aim to study it further and identify its characteristics.

METHOD

Eight specimens were dissected from four cadavers. Two were stained and examined under magnification in both polarized and non polarized light. The remaining 6 were subjected to micrometer testing of their tensile properties.

RESULTS

Both the histological features and mechanical properties were consistent with tendon; with cross sectional area, ultimate tensile strength and stiffness varying between specimens.

CONCLUSIONS

Based on its location and properties, the FHCI tendon may be involved in limiting dorsiflexion of the first MTP joint and could have clinical relevance in pathological processes around both the first and second MTP joints. Clin. Anat., 33:689-695, 2020. © 2019 Wiley Periodicals, Inc.

Calcaneal osteochondroma masquerading as plantar fasciitis: An approach to plantar heel pain - A case report and literature review

BACKGROUND

Heel pain is a common orthopaedic complaint, and if left untreated can be a source of chronic morbidity. Accurate diagnosis can be challenging, owing to the complex anatomy and multiple pain generators present in the foot. We aim to share our clinical experience managing an unusual case of chronic heel pain secondary to osteochondroma.

CASE SUMMARY

A 41-year-old obese male who works as a porter presented with a long-standing history of left plantar heel pain. He was assessed to have point tenderness over the plantar insertion of the calcaneus as well as a positive Silfverskiöld test. He was treated for plantar fasciitis and tight gastrocnemius but failed conservative therapies as well as surgical intervention. Magnetic resonance imaging revealed the presence of a pedunculated bony protrusion over the plantar aspect of the calcaneus. The decision was made for excision of the osteochondroma, and the patient has been pain-free since.

CONCLUSION

Osteochondromas are rarely symptomatic in skeletally mature patients. While most are benign with a very low risk of malignant transformation, surgical excision can yield excellent results and significant pain relief in symptomatic patients.

Prediction on the plantar fascia strain offload upon Fascia taping and Low-Dye taping during running

Background

Taping is commonly prescribed to treat plantar fasciitis for runners by virtue of its alleged ability to offload the plantar fascia and facilitate positive injury prognosis. Our study aimed to investigate how different taping methods could change the loading on the plantar fascia during running using computational simulations.

Methods

A finite element foot model was modified from a previous version to fit the study's purpose. The model featured twenty bones, bulk soft tissue, foot muscles, ligaments/tendons, and a solid part representing the plantar fascia. A runner performed several running trials under one untaped condition and two taped conditions—Low-Dye taping and Fascia taping, which were implemented by a physiotherapist using the Kinesio tapes. The captured motion data were processed to drive a scaled musculoskeletal model and calculate segmental kinematics, foot muscle force, and joint reaction force. These variables were then input as the boundary/loading conditions for finite element analyses of running. The principal tensile strain on the plantar fascia, subtalar eversion, and navicular height during the stance phase were averaged across five trials of each condition and compared using Friedman's test.

Results

Maximal subtalar eversion did not differ among conditions (p = 0.449). Fascia taping significantly reduced maximal strains on the fascia band (p = 0.034, Kendall's W = 0.64–0.76) and increased the navicular height (p = 0.013, Kendall's W = 0.84) compared with nontaping. There were no significant differences in all outcome variables between Low-Dye taping and nontaping (p = 0.173–0.618).

Conclusion

From a mechanical point of view, our study provided quantitative evidence to support the application of taping treatments for overstrained plantar fascia. The untensed fascia band by Fascia taping could be a potential indicator of pain relief for the runners. However, a prospective study targeting the patient population would be needed to address the point.

The Translational Potential of this Article

The study quantified the loading status of the plantar fascia during running and provided mechanical evidence to support the usage of taping as a mean to reduce fascial strain, thus possibly controlling injury risks for the runners. The results of the study also highlighted the importance of selecting specific taping methods based on individuals' needs.

The Role of Plantar Fascia Tightness in Hallux Limitus: A Biomechanical Analysis

Restriction of greater toe dorsiflexion without degeneration of the first metatarsophalangeal joint is defined as hallux limitus. We assume that in hallux limitus the limitation of greater toe dorsiflexion takes place in the terminal stance phase because of massive tightening of the calf and plantar structures. The current study investigated the role of a tight plantar fascial structure in impairing dorsiflexion of the greater toe. For the purpose of the study, 7 lower limbs from Thiel-fixated human cadavers were evaluated. To simulate double-limb standing stance, the tibia and fibula were mounted on a materials testing machine and constantly loaded with 350N. Additionally, the tendons of the specimens were loaded using a custom-made system. The plantar fascia was fixed to a clamp and tensioned using a threaded bar. Four different tensile forces were then applied to the plantar fascia (approximately 100, 200, 300, and 350 N) and the extension of the first toe was measured. The results show a significant positive correlation between the decrease in extension of the hallux and the tension applied to the plantar fascia reaching a maximum mean decrease of 4.2° (117% compared with the untightened situation) for an applied tension of 364N.

Anatomical variations of the plantar fascia's origin with respect to age and sex-an MRI based study

The plantar fascia (PF) plays a significant role in ankle movement and anatomical variations of this structure may significantly alter the biomechanical properties of the foot and lower extremity. The aim of this study was to evaluate the changes of the PF's origin point on the calcaneus (CB), and whether these changes are dependent on age and sex. Two independent observers evaluated two hundred and two foot and ankle MRIs and the following measurements was performed: (A) horizontal length of the AT insertion into the posterior aspect of the CB, (B) horizontal length of the CB and (C) horizontal distance from the most anterior point of the CB to the most posterior part of the PF. Statistical analysis was performed with the results obtained to evaluate both sex and age differences. Based on our results, we observed that: (1) changes of the PF's origin point on the CB is independent of age and sex and (2) the continuity between the PF and AT decreases during aging as a result from changes in the AT's insertion point into the CB. This study concludes that the PF's origin point does not change with respect to age or sex, but the continuity between the PF and AT decreases during aging. Knowledge regarding the biomechanical influences caused by changes in the relationship between the AT and PF may be important in terms of treatment and prophylaxis of both PF and AT pathologies. Clin. Anat. 32:597-602, 2019. © 2019 Wiley Periodicals, Inc.