Biomechanics of the first ray part V: The effect of equinus deformity. A 3-dimensional kinematic study on a cadaver model

Special Considerations in Podiatric Science: Translational Research, Cadavers, Gait Analysis, Dermatology, and Databases

The objective of this article is to provide a brief overview of the critical analysis and design of unique and perhaps less common methodologies in podiatric science. These include basic science translational designs, cadaveric investigations, gait analyses, dermatologic studies, and database analysis. The relative advantages, disadvantages, and inherent limitations are reviewed with an intention to improve the interpretation of results and advance future foot and ankle scientific endeavors.

Midfoot width changes after first metatarsal osteotomy in hallux valgus surgery: A biomechanical effect?

Hallux valgus is a challenging pathology characterized by a valgus deformity in the metatarsophalangeal area of the first ray. The aim of this study was to analyze the influence of first metatarsal osteotomy on the relationship between midfoot bones in patients with hallux valgus. The sample consisted of patients from the orthopedics and traumatology outpatient clinic who underwent surgical treatment for hallux valgus. Preoperative and postoperative X-rays were compared regarding the width of the midfoot and the tarsometatarsal joint. The sample consisted of 17 women, with 22 feet assessed in each group. The distance from the medial cuneiform to the cuboid, the distance from the intermediate cuneiform to the cuboid, the distance between the first and fifth metatarsals, and the distance between the second and fifth metatarsals reduced significantly between pre- and postoperative assessments. Hallux valgus correction through osteotomy of the first metatarsal leads to a structural change in the midfoot. Further studies should determine whether these changes persist over time.

The Application of Morton's Observations to Contemporary Treatment of Foot Dysfunction

Understanding the evolution of the human foot from a flexible grasping structure to one that is designed for upright posture and locomotion is paramount to treating patients with foot pain and dysfunction. Almost 100 years ago, Dudley Morton observed that certain retained atavistic traits are responsible for pathologic breakdown of the modern foot. Cadaveric research under the direction of Jeffrey Christensen provided evidence that lengthening the gastrocnemius and stabilizing the medial column helped correct the faulty biomechanics associated with Morton foot and corroborated Hansen's blueprint for reconstructive surgery of the foot and ankle.

Characteristics of Pressure on the Apophysis in the Course of Paediatric Heel Pain-Preliminary Report

Increased pressure on the heel apophysis is often implicated as a cause of paediatric heel pain. However, there are few reports on the causes of the increased pressure and its origin. Therefore, the aim of this study was to analyse the distribution of pressure on the feet in children with heel pain. The study included 33 paediatric patients with non-traumatic heel pain, i.e., 24 boys (73%) and 9 girls (27%), aged on average 11.2 years (±3 years). Pedobarographic diagnostics proved a decrease in the pressure on the heels in relation to the ground and the transfer of the projection of the centre of gravity to the forefoot. While standing, the average contribution of the pressure on the heel was 0.52, SD = 0.14 in children with normal and reduced weight. In overweight children, the average pressure on the heel was higher (0.60, SD = 0.08), but the small number of children with this characteristic (n = 4) did not allow conclusions to be drawn in this area. Heel underload was also demonstrated during gait. However, the assessment of this aspect requires additional observational analyses in the field of propulsion and gait phases. The reduced pressure on the heel promotes apophysis traction, causing intracanal compression. Studies have shown that the causes of apophysis traction may be postural defects (in particular, forward inclination of body posture) and overpronation of the foot, or defects in the metatarsal area.

Addressing Medial Column Instability in Flatfoot Deformity

A stable medial column is important to the normal function of the foot and ankle. Medial column instability and forefoot varus can result in compensatory hindfoot motion leading to stress along the medial soft-tissue structures. Medial column stabilization should therefore be considered when (1) forefoot varus deformity is identified following hindfoot realignment; (2) pronounced medial column instability is present, even in the absence of forefoot varus; and (3) when degenerative changes are present within the medial column articulations. Common surgical procedures include arthrodesis of the talonavicular joint, naviculocuneiform joint, and first tarsometatarsal joint, as well as osteotomy of the medial cuneiform (Cotton osteotomy).

Improved Gait and Radiological Measurements After injection of Botulinum Toxin Into Peroneus Longus in Young Children With USCP and Equinovalgus Gait

BACKGROUND

Children with cerebral palsy develop foot deformities due to a combination of factors including muscle shortening, hypertonia, weakness, and cocontraction of muscles acting at the ankle joint resulting in an altered gait pattern. We hypothesized these factors affect the peroneus longus (PL) and tibialis anterior (TA) muscles couple in children who develop equinovalgus gait first followed by planovalgus foot deformities. Our aim was to evaluate the effects of abobotulinum toxin A injection to the PL muscle, in a cohort of children with unilateral spastic cerebral palsy and equinovalgus gait.

METHODS

This was a prospective cohort study. The children were examined within 12 months before and after injection to their PL muscle. Twenty-five children of mean age 3.4 (S.D.: 1.1) years were recruited.

RESULTS

We found significant improvement in foot radiology measures. Passive extensibility of the triceps surae did not change, whereas active dorsiflexion increased significantly. Nondimensional walking speed increased by 0.1 (95% confidence interval [CI], [0.07, 0.16]; P < 0.001), and the Edinburgh visual gait score improved by 2.8 (95% CI, [-4.06, -1.46]; P < 0.001). Electromyography showed increased recruitment for gastrocnemius medialis (GM) and TA but not for PL during the reference exercises (standing on tip toes for GM/PL, active dorsiflexion for TA) and decreased activation percentages for PL/GM and TA across sub-phases of gait.

CONCLUSIONS

One key advantage of treating the PL muscle only might be to address foot deformities without interfering with the main plantar flexors that are instrumental to support body weight during gait.

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

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

Effect of the First Tarsometatarsal (Modified Lapidus) Arthrodesis on Hindfoot Alignment

The purpose of this study is to demonstrate the effect of first tarsometatarsal (modified Lapidus) arthrodesis on hindfoot alignment. We reviewed the radiographs of 39 patients, 40 feet (16 right feet and 24 left feet in 6 males and 34 females; mean age 43 years) who underwent hallux valgus reconstruction and isolated first tarsometatarsal arthrodesis. Patients who had ancillary osseous procedures were excluded from the study, with the exception of proximal phalangeal osteotomy to address hallux interphalangeus. The mean time to follow up was 33.78 weeks (8.45 months), median 21.5 weeks. Statistically significant differences were found between preoperative and postoperative measurements for talar declination (-3.3 ± 3.5), lateral talocalcaneal angle (-3.1 ± 3.9), lateral Meary's angle (-4.2 ± 4.9), medial cuneiform height (3.5 ± 4.6), medial cuneiform to fifth metatarsal distance (4.7 ± 4.5), AP talocalcaneal angle (-2.8 ± 5.3), and percentage of talar head uncovering (-6.6 ± 7.6). Our results suggest that first tarsometatarsal arthrodesis can affect hindfoot alignment on AP and lateral radiographs.

Medial Column Biomechanics: Nonsurgical and Surgical Implications

Understanding of medial column biomechanics is paramount to a successful outcome in both conservative and surgical treatment. Dysfunctions of the dynamic stabilizers as well as the static stabilizers of the medial column play a role in pathomechanics. Conservative options for addressing the medial column include custom foot orthotics and bracing. Options for addressing the medial column surgically with the goal to restore a stable tripod configuration, include first tarsometatarsal joint arthrodesis, opening plantarflexory medial cuneiform osteotomy, and naviculocuneiform arthrodesis.

Lower Extremity Biomechanical Examination of Athletes

A comprehensive lower extremity examination is a critical examination component for any type of injury in an athlete but should also be part of a preseason or preventive care program. Identification and treatment of biomechanical abnormalities and association with evidence-based risk factors for lower extremity disorders can be incorporated to potentially reduce risk or prevent acute and chronic injuries.

The Lateral Column

Lower extremity biomechanics is the cornerstone of podiatric medicine and surgery. The foot and ankle act as the interface between the ground and proximal segments, mediating internal and external moments Although the medial longitudinal arch has been widely researched, the details of the lateral longitudinal arch are less extensively delineated. The purpose of this review is to analyze the biomechanics of the lateral column as it relates to lower extremity biomechanics and function.

Sex Differences in the Footprint Analysis During the Entire Gait Cycle in a Functional Equinus Condition: Novel Cross Sectional Research

Some studies suggest that gender is related to gait. Females show significantly higher ankle motion and vertical ground reaction forces. Males have significantly larger plantar contact surface areas in all regions of the foot than females in most, but not all, prior studies. However, there is no research on sex differences in a functional equinus condition. In this study, 119 individuals, including 59 females (29.7 ± 5.15 years, 58.74 ± 6.66 kg, 163.65 ± 5.58 cm) and 60 males (31.22 ± 6.06 years, 75.67 ± 9.81 kg, 177.10 ± 6.16 cm), with a functional equinus condition walked onto a pressure platform. In two separate testing sessions, five trials of each foot were conducted for the first, second, and third steps. We measured the contact surface areas for each of the three phases of the stance phase. We computed the intraclass correlation coefficient and standard error of the mean to assess the reliability. We found significantly greater contact surface areas in males than females in the first, second, and third steps in all phases of the stance phase: heel strike, mid-stance, and take-off. This is important information for the design of footwear and orthotics and gender knowledge. In a functional equinus condition, males have registered greater contact surface areas than females in all phases of the dynamic footprint of the stance phase.

Hallux Valgus

Hallux valgus is a common condition that results from a complex positional deformity of the first ray. The bunion or medial prominence that results from the lateral deviation and pronation of the hallux is only one component of the 3-dimensional deformity. Hallux valgus can lead to considerable pain and altered joint mechanics. The precise biomechanical etiology remains under debate. Predisposing factors include female sex, age, constricting footwear, and family history. Metatarsus adductus, equinus contracture, hammertoe deformity, and pes planus often coexist with hallux valgus. Nonoperative treatment involves patient education, shoe modifications, toe pads and positioning devices, and activity modifications. Surgery is considered in patients who fail nonoperative treatment with the goal of pain relief, correction of the deformity, improved first ray stability, and improved quality of life. More than 100 different procedures have been described to treat hallux valgus; they include combinations of soft tissue balancing, metatarsal osteotomies, and fusion of either the metatarsophalangeal (MTP) or tarsometatarsal (TMT) joint. The choice of procedures depends on the severity and location of the deformity as well as surgeon preference. Recent advances in operative techniques include minimally invasive surgery and correction of rotational deformity.

Effects of Compressive Stockings and Standard Stockings in Skin Temperature and Pressure Pain Threshold in Runners with Functional Ankle Equinus Condition

OBJECTIVE

To assess clinical differences in the Achilles tendons of runners with ankle equinus wearing either compressive or standard stockings.

DESIGN

Case⁻control study.

METHODS

In this study, we conducted clinical examinations of 98 sportsmen (runners) with equinus, before and after 30 min of running on a treadmill; 49 runners wore compressive stockings and 49 wore standard stockings. Clinical assessments of the runners' Achilles tendons were based on the pressure pain threshold (PPT) and skin temperature analysis.

RESULTS

Achilles tendon evaluations identified significant differences in skin temperature modification and PPT between the compressive and standard stocking groups.

CONCLUSIONS

Based on our findings, we propose that higher skin temperatures are associated with lower pressure pain thresholds in the Achilles tendons of runners with ankle equinus.

The Gradual and Acute Correction of Equinus Using External Fixation

Equinus is one of the most common deformities noted in foot and ankle biomechanics that, at times, if not identified and managed properly may lead to significant lower extremity pathology. With that being said, this deformity is also one that may be both underdiagnosed and undertreated. Treatment for equinus can range from conservative therapy to more aggressive surgical therapy. The purpose of this article is to review the clinical workup to properly identify the deformity and to explore the various treatment options for its timely management, which include gradual or acute correction of equinus using external fixation.

To Evaluate the Effectiveness of TBTS - A Novel Device to do Self-Stretching of Gastroc-Soleus Muscle in Patients with Equinus Deformity

INTRODUCTION

Various methods have been used for management of equinus deformity. However, stretching gastroc-soleus muscle and achilles tendon is a difficult task. It is labour intensive, which makes the provision of treatment difficult for many patients.

AIM

To study the effectiveness of Tension Bar Tendon Stretch (TBTS) compared to conventional stretching in patients with equinus deformity in terms of improvement in equinus angle and spasticity.

MATERIALS AND METHODS

A prospective randomised case control study was done on 16 patients of both the sexes in the age group four years to 56 years. Patients were stratified based on presence or absence of spasticity. Patients were further randomly allotted to the study or control group. Study group received stretching with TBTS in addition to the conventional rehabilitation programme. Patients were assessed in terms of improvement in equinus deformity and spasticity (modified Ashworth scale). These indices were measured at 0 month (pre-treatment), 1 month (post-treatment), and 6 months (follow up).

RESULTS

Equinus deformity in patients with spastic equinus changed from 22.4° to 12° in study group while in control group change was from 21° to 17°. The difference was statistically significant with p-value of 0.001. Non-spastic (post accidental) changed from 30° to 15° in study group while in control group change was from 31° to 23° with p-value of 0.001. Modified Ashworth Score (MAS) was assessed only in spastic equinus, while in study group MAS changed from 2.8 to 1.5 and MAS change was 2.6 to 2 in control group; this difference after six months of therapy was statistically significant with a p-value of 0.001.

CONCLUSION

TBTS can be an effective tool in rehabilitation of patients having equinus deformity; it provides an effective and patient controlled stretching and no need for a physical therapist. TBTS is a novel but simple instrument that can be made locally by the patient or the family.

Equinus and Lengthening Techniques

Equinus is linked to most lower extremity biomechanically related disorders. Defining equinus as ankle joint dorsiflexion less than 5° of dorsiflexion with the knee extended is the basis for evaluation and management of the deformity. Consistent evaluation methodology using a goniometer with the subtalar joint in neutral position and midtarsal joint supinated while dorsiflexing the ankle with knee extended provides a consistent clinical examination. For equinus deformity with an associated disorder, comprehensive treatment mandates treatment of the equinus deformity. Surgical treatment of equinus offers multiple procedures but the Baumann gastrocnemius recession is preferred based on deformity correction without weakness.

The relationship between foot posture index, ankle equinus, body mass index and intermetatarsal neuroma

Background

The main purpose of this study was to investigate the presence of an association between intermetatarsal neuroma and foot type, as measured by the Foot Posture Index. The study also examined whether there was a relationship between foot type and the interspace affected with intermetatarsal neuroma, and whether ankle equinus or body mass index had an effect.

Methods

In total, 100 participants were recruited from The University of Western Australia’s Podiatry Clinic, 68 of whom were diagnosed with inter-metatarsal neuroma from 2009 to 2015. There were 32 control participants recruited from 2014 to 2015. The age of subjects was recorded, as were weight and height, which were used to calculate body mass index. The foot posture index and ankle dorsiflexion were measured using standard technique. Independent t-tests and Kruskal-Wallis tests were used to compare differences in foot posture index, body mass index and ankle dorsiflexion between the inter-metatarsal neuroma and control groups. Multivariable logistic regression was also used to model relationships for outcome.

Results

The 68 intermetatarsal neuroma subjects had a mean age of 52 years (range 20 to 74 years) and comprised of 56 females and 12 males. The 32 control subjects had a mean age of 49 years (range 24 to 67 years) with 26 females and six males. There were no significant differences between the control and the intermetatarsal neuroma groups with respect to the mean foot posture index scores of the left and right foot (p = 0.21 and 0.87, respectively). Additionally no significant differences were detected between the affected intermetatarsal neuroma interspace and foot posture index (p = 0.27 and 0.47, respectively). There was no significant difference in mean body mass index between the intermetatarsal neuroma (26.9 ± 5.7) and control groups (26.5 ± 4.1) (p = 0.72). There was, however, a significant difference in mean ankle dorsiflexion between the intermetatarsal neuroma and control groups (p < 0.001 for both feet). Logistic regression models, adjusted for age, sex, foot posture index and body mass index estimated that the odds of having an intermetatarsal neuroma in the right foot increased by 61% (OR 1.61; 95% CI 1.32–1.96) with each one degree reduction of ankle dorsiflexion, and in the left foot by 43% (OR 1.43; 95% CI 1.22–1.69).

Conclusion

No relationships were found between foot posture index and body mass index with intermetatarsal neuroma, or between foot posture index and the interspaces affected. However, a strong association was demonstrated between the presence of intermetatarsal neuroma and a restriction of ankle dorsiflexion.

Subtalar Arthroereisis Implant Removal in Adults: A Prospective Study of 100 Patients

Subtalar joint arthroereisis (STA) can be used in the management of adult acquired flatfoot deformity (AAFD), including posterior tibial tendon dysfunction. The procedure is quick and normally causes little morbidity; however, the implant used for STA often needs to be removed because of sinus tarsi pain. The present study evaluated the rate and risk factors for removal of the implant used for STA in adults treated for AAFD/posterior tibial tendon dysfunction, including patient age, implant size, and the use of endoscopic gastrocnemius recession. Patients undergoing STA for adult acquired flatfoot were prospectively studied from 1996 to 2012. The inclusion criteria were an arthroereisis procedure for AAFD/posterior tibial tendon dysfunction, age >18 years, and a follow-up period of ≥2 years. The exclusion criteria were hindfoot arthritis, age <18 years, and a follow-up period of <2 years. A total of 100 patients (average age 53 years) underwent 104 STA procedures. The mean follow-up period was 6.5 (range 2 to 17) years. The overall incidence of implant removal was 22.1%. Patient age was not a risk factor for implant removal (p = .09). However, implant size was a factor for removal, with 11-mm implants removed significantly more frequently (p = .02). Endoscopic gastrocnemius recession did not exert any influence on the rate of implant removal (p = .19). After STA for AAFD, 22% of the implants were removed. No significant difference was found in the incidence of removal according to patient age or endoscopic gastrocnemius recession. However, a significant difference was found for implant size, with 11-mm implants explanted most frequently.

Threshold of equinus which alters biomechanical gait parameters in children

The main aim of this study was to define the threshold angle of equinus beyond which significant changes in 3D lower limb kinematics and kinetics occur in typically developing children and to describe these changes.A customized orthosis was fitted on the right ankle of 10 typically developing children and was adjusted to +10° ankle dorsiflexion, 0°, -10°, -20° plantarflexion and maximum plantarflexion. Gait was analyzed using an optoelectronic system. A gait velocity of 1m/s was imposed.Most of the kinematic and kinetic changes were significantly altered from the -10° condition. In the sagittal plane, the results showed increased knee flexion at initial contact, increased knee flexion or hyperextension in stance, increased hip flexion at initial contact and increased anterior pelvic tilt. Other changes included increased knee varus, reduced hip adduction and more internal foot progression. The ankle plantarflexion moment was bi-phasic during stance, peak ankle power generation was reduced, peak knee extension moment was decreased and hip extension moments increased. On the contralateral side, there was a significant increase in ankle plantarflexion at initial contact and a significant decrease in knee flexion during swing phaseat maximum plantarflexion.Although slight modifications occurred for smaller degrees of equinus, the results suggest that significant kinematic and kinetic changes occurred during gait in both limbs from 10° of plantarflexion. The results of this study also provide some indications regarding the primary causes of gait deviations and secondary compensatory strategiesin children with a clinical dorsiflexion limitation.

Biofeedback baropodometry training evaluation: a study with children with equinus foot deformity

The lack of perception in the hindfoot increases the plantar flexion, causing irregular posture due to the foot position, a disability known as equinus foot deformity. A portable device, named baropodometer, that measures the pressure at the forefoot and hindfoot regions was built to help this population in terms of balance and posture correction. Ten hemiparetic teenager volunteers with equinus foot participated in the experiments. The results demonstrated that the proposed device increased the weight-bearing in upright stance in the paretic side, decreasing the weight in the non-paretic side. After 10 experimental sessions, performed along 6 months, the distribution of the pressure in the lower limbs was very similar. The baropodometer facilitates the rehabilitation, by biofeedbacking the pressure of the calcaneus, using the volunteer's audiovisual system. The rehabilitation using the proposed device was able to recover the balance by posture correction, facilitating future gait training of these volunteers.

Dynamic equinus with hindfoot valgus in children with hemiplegia

In children with hemiplegia, it is important to distinguish between equinus with hindfoot varus (equinovarus) or valgus (equinovalgus). Premature onset of medial gastrocnemius (GM) EMG in individuals with equinus is well documented. Premature onset of Peroneus longus (PL) EMG has been described in neurologically impaired adults with equinovalgus, but not in children. Our aim was to record the onset of PL and GM activity on the hemiplegic side of children with equinovalgus deformity. Fifteen children GMFCS 1 (3.8 yrs ± 2) with hemiplegia had a goniometric assessment of passive ankle range of motion and assessment of ankle function from video and surface EMG recording during gait. The clinical and video observations were used to determine the equinovalgus, as defined by Wren, at initial contact (IC). The premature onset of muscle activity was normalised as a swing (SW) percentage prior to IC of the following stance (ST). A paired T-test compared the onset of muscle activity between PL and GM. The ankle passive dorsiflexion was 13° ± 12° (hemiplegic side) versus 18° ± 10° (non-involved side) (p<0.05). For the non-involved limb, the onset of GM activity was at 14% of the gait cycle (midstance), the onset of PL activity was at 19% (p<0.05). For the hemiplegic limb with equinovalgus, there was a premature onset activity of PL (-24%) and GM(-8%) (p<0.001). On the non involved side, the onset of PL activity occurred, as in adults, after the onset of GM activity, during ST. On the hemiplegic side, there was no triceps surae contracture and the onset of PL activity occurred prior to the onset of GM activity, during terminal SW. This study confirmed the overactivity of PL in hemiplegic children with equinovalgus.

Effect of the posterior tibial and peroneal longus on the mechanical properties of the foot arch

BACKGROUND

The mechanical properties of the foot are controlled by many structures including muscles, tendons, ligaments, tarsal joints and bones. Among them, muscles make the dynamic changes of foot alignment, especially the posterior tibial (PT) and peroneal longus (PL) which contribute to maintaining the foot arch. The purpose of this study was to quantify the effect of PT and PL on the foot mechanical properties.

METHODS

The mechanical properties with a longitudinal load to the tibia was measured in eight cadaveric feet. The measurement was carried out with absence of tendon traction (control), the presence of isolated traction of each tendon of the PT or PL, and finally after simultaneous traction of both tendons.

RESULTS

The bone displacement significantly decreased with tendon traction. The stiffness significantly increased with PT traction compared to control, and significantly decreased with PL traction and with traction of both tendons. Among the four testing conditions, the energy during loading was least with isolated PT traction. The energy dissipation rate was significantly increased with PL traction and with traction on both tendons, whereas no significant difference existed with PT traction compared to control.

CONCLUSIONS

The PT increased the stiffness and reduces the energy stored in the foot. The PT acted to improve the energy efficiency of the load transmission. The PL decreased the stiffness and increased the energy stored.

CLINICAL RELEVANCE

PT and PL muscles affect the foot arch. Excessive or insufficient traction may cause some foot disorders.

Simulation of unilateral equinus using an adjustable orthosis in children: design, feasibility and biomechanical effects

BACKGROUND AND AIM

In order to increase understanding of the biomechanical consequences of equinus foot on gait, we developed an orthosis to induce an adjustable degree of unilateral equinus. The aim of this study was to evaluate its feasibility and consequences on 3D ankle kinematics and kinetics.

TECHNIQUE

3D gait analysis was carried out in 10 healthy children without the orthosis, with the non-adjusted orthosis and with the orthosis adjusted to +10°, 0°, -10°, -20° of ankle dorsiflexion and maximum plantarflexion (MP). The amount of dorsiflexion at initial contact was close to the goniometric measurement. Significant kinematic and kinetic changes occurred at -10°, -20° and MP. The mean maximum equinus at initial contact -21.65° ± 4.17 and during stance -11.61° ± 4.82 were larger than those obtained with previous described devices.

DISCUSSION

Our device was easy-to-use and induced an adjustable, well tolerated equinus. It provides a new way to simulate equinus and its biomechanical consequences on gait.

Evaluation and biomechanics of the first ray in the patient with limited motion

Adequate first ray function is essential to healthy human gait. Controversies still exist about aspects of human structure and function and many newer answers and theories have been proposed by a new generation of experts. Examples include the sagittal plane facilitation, tissue stress, and preferred movement pathway theories. This article also presents a summary of how to provide a thorough, detailed, and accurate first ray examination on the individual with limited motion. This article explores functional first ray mechanics in both a theoretic and biomechanical perspective, as well as a practical, hands-on examination perspective.

Radiographic outcomes of adult acquired flatfoot corrected by medial column arthrodesis with or without a medializing calcaneal osteotomy

Medial column arthrodesis and calcaneal osteotomies are commonly used for adult acquired flatfoot surgical reconstruction. In this retrospective study, 41 patients (47 feet) with a mean age of 55 ± 13.5 years underwent a medial column arthrodesis, with or without calcaneal osteotomy, between 1999 and 2007. The indication for surgery was a painful flatfoot deformity with peritalar subluxation, and a fault in the naviculocuneiform joint. At a mean of 9.6 (range 3-43) months postoperatively, in patients who underwent a medial column arthrodesis, radiographs showed a mean decrease in the talonavicular coverage angle of 10.2° ± 8.7° (P < .001), and mean increases in the lateral talometatarsal and calcaneal inclination angle of 10.7° ± 5.1° (P < .001) and of 3.2° ± 2.7° (P < .001), respectively. In patients who underwent a combined medial column arthrodesis and a medializing calcaneal osteotomy, the talonavicular coverage angle decreased by a mean of 12.1° ± 6.1° (P < .001), while the lateral talometatarsal angle and calcaneal inclination angle increased by a mean of 12.3° ± 6.1° (P < .001) and 3.1° ± 2.7° (P < .001), respectively, from preoperative values. Four nonunions (4 of 47, 8.51%) occurred at the naviculocuneiform joint and 1 nonunion (1 of 32, 3.13%) occurred at the tarsometatarsal joint. These findings demonstrate marked improvement of radiographic flatfoot parameters following a medial column arthrodesis with or without a medializing calcaneal osteotomy.

The role of an extended medial column arthrodesis for Charcot midfoot neuroarthropathy

The etiology of diabetic Charcot neuroarthropathy involving the midfoot often includes an inciting traumatic event or repetitive micro-trauma from an uncompensated biomechanical imbalance that potentiates an incompletely understood pathway leading to a rocker-bottom foot deformity and ulceration. In the setting of a severe Charcot foot fracture and/or dislocation with obvious osseous instability, diagnostic delay can potentiate the limb-threatening sequelae of infected midfoot ulcerations in this patient population. In this article, the authors discuss the thought process as well as the advantages of performing an extended medial column arthrodesis for selected Charcot midfoot deformities.

Introduction: The first metatarsal: it's importance in the human foot

For the past 100 years or so, the approach foot and ankle surgeons have taken too often has been to make compensating deformities or to do dysfunctional fusions. There is now a much improved understanding of the foot and attempt to restore normal anatomy, alignment, muscle balance, and function whenever possible. In a way, clinicians try to complete the evolutionary goal for the ideal foot for a biped. The first metatarsal is the key structure in this effort.

Subtalar joint arthroereisis in adult-acquired flatfoot and posterior tibial tendon dysfunction

The concept of subtalar arthroereisis seems to be gaining popularity in adult-acquired flatfoot surgery. There is wide acceptance of this approach in the pediatric population, but the use of these devices in the adult population is still controversial. Care needs to be taken to select the proper patients and to avoid overuse of these devices. The authors believe these implants will continue to provide a significant benefit to certain patients when selected properly.

In vitro study of foot kinematics using a dynamic walking cadaver model

There is a dearth of information on navicular, cuboid, cuneiform and metatarsal kinematics during walking and our objective was to study the kinematic contributions these bones might make to foot function. A dynamic cadaver model of walking was used to apply forces to cadaver feet and mobilise them in a manner similar to in vivo. Kinematic data were recorded from 13 cadaver feet. Given limitations to the simulation, the data describe what the cadaver feet were capable of in response to the forces applied, rather than exactly how they performed in vivo. The talonavicular joint was more mobile than the calcaneocuboid joint. The range of motion between cuneiforms and navicular was similar to that between talus and navicular. Metatarsals four and five were more mobile relative to the cuboid than metatarsals one, two and three relative to the cuneiforms. This work has confirmed the complexity of rear, mid and forefoot kinematics. The data demonstrate the potential for often-ignored foot joints to contribute significantly to the overall kinematic function of the foot. Previous emphasis on the ankle and sub talar joints as the principal articulating components of the foot has neglected more distal articulations. The results also demonstrate the extent to which the rigid segment assumptions of previous foot kinematics research have over simplified the foot.