Graphic analysis of forces acting upon a simplified model of the foot

Application of a graphical technique to analyse internal forces on a simplified model of the foot in various external loading patterns. The method is applied when the external load is acting purely upon the forefoot, the hindfoot and on both locations. The pes planus situation and the effect of the "rocker" and inlay sole are studied.     

The relationship between the hindfoot angle and the medial longitudinal arch of the foot

INTRODUCTION: The relationship of hindfoot valgus and the medial longitudinal arch (MLA) is a well-known parameter for the evaluation of the foot deformities. In this study, we evaluated the relationship between the hindfoot angle and the MLA and the effect of these parameters on the development and general joint laxity of the subjects. METHODS: Two-hundred-sixty-one volunteers who had no foot pain or major foot deformity were examined. The age range of the volunteers was 4 to 20 years. For each subject, the right foot was evaluated for the clinical hindfoot angle and footprint analysis. General ligamentous laxity also was recorded. Arch index and valgus index were used for the evaluation of the footprint analysis, and the valgus angle was measured clinically. RESULTS: The average heel valgus angle for all subjects was 5.2 (SD 3.3) degrees. The means of valgus index and arch index were 3.34 (SD, 5.6) and 0.7 (SD, 0.2), respectively. Although there was a positive correlation between the valgus angle and valgus index (p = 0.027), the arch index was not found to be correlated with these values. Positive correlation between joint laxity and arch height also was demonstrated (p < 0.05). CONCLUSIONS: We concluded that the hindfoot angle and MLA height must be considered separately in clinical practice, particularly in the management of childhood pes planus.     

Arthrodesis of the subtalar and talonavicular joints for correction of symptomatic hindfoot malalignment

BACKGROUND: Triple arthrodesis has long been used for the treatment of painful malalignment or arthritis of the hindfoot. However, the effect of fusion on adjacent joints has sparked interest in a more limited arthrodesis in patients without involvement of the calcaneocuboid joint. METHOD: Results of 16 feet in 14 patients who had a modified double arthrodesis for symptomatic flatfoot, cavovarus deformity, or hindfoot arthritis were reviewed retrospectively with a minimum followup of 18 (range 18 to 93) months. The most common diagnosis contributing to the hindfoot deformity was pes planovalgus. All operations were done with a consistent technique using rigid internal fixation with screws. In 15 feet, a concomitant gastrocnemius recession for equinus contracture was done at the time of the primary surgery. Clinical evaluation was based on the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale in addition to subjective assessments of pain, function, shoewear, cosmesis, and overall satisfaction. Radiographic evaluation included measurements of the anterior-posterior talo-second metatarsal angle, lateral talocalcaneal angle, and lateral talo-first metatarsal angle, and notation of arthritic changes of the ankle, calcaneocuboid, and midfoot joints, as well as an assessment of time to union of all arthrodeses. RESULTS: The average AOFAS Ankle-Hindfoot Scale improved from 44.7 preoperatively to 77.0 postoperatively (p < 0.01). Subjectively, patients experienced improvements in pain, function, cosmesis, and shoewear. Overall, all patients were satisfied and would have the procedure again under similar circumstances. Radiographically, all parameters statistically improved. There was an increase in arthritic scores for six ankle, six calcaneocuboid, and five midfoot joints. One talonavicular joint nonunion occurred in a rheumatoid patient, requiring revision arthrodesis. CONCLUSIONS: We have concluded that simultaneous arthrodesis of the talonavicular and subtalar joints is a reasonable treatment in the subset of patients with symptomatic hindfoot malalignment whose calcaneocuboid joints are not involved in the primary disease.     

Clinical biomechanics of the peritalar joint

The peritalar joint includes the articulations between the talus and calcaneus and the talus and navicular. Motion between the talus and calcaneus is described most often as rotation about an axis that points medially, anteriorly, and superiorly. This motion is considered to be triplanar, with inversion, plantar flexion, and adduction occurring together, whereas eversion, dorsiflexion, and abduction are associated. Similar motions have been described between the talus and navicular. Foot deformity, such as a pes planus or a pes cavus foot type, and hindfoot or midfoot joint fusion can alter the biomechanics of the peritalar joint.     

The correlation between pes planus and anterior knee or intermittent low back pain

BACKGROUND: Anterior knee pain and intermittent low back pain are among the most common orthopedic complaints of adolescents. However, little is known about pes planus and its relative risk for these symptoms. The goal of the study was to track the prevalence of pes planus in adolescents, and examine its associated risk to anterior knee pain and intermittent low back pain, respectively. MATERIALS AND METHODS: A retrospective study of 97,279 military recruits presenting to recruitment centers was conducted. Pes planus was graded by an orthopedist as mild, moderate or severe according to the flattening of the plantar arch and its rigidity to standing on one's toes. Anterior knee pain was diagnosed when symptoms were attributed to the patellofemoral joint. Intermittent low back pain was diagnosed when there was pain but neither abnormal clinical nor radiographic findings. RESULTS: Pes planus was present in 15,698 (16%) individuals. 11,549 (74%), 3,341 (21%) and 808 (5%) were diagnosed as having mild, moderate and severe pes planus, respectively. The prevalence of intermittent low back pain was 5% in both the control and mild pes planus groups, while it was 10% in the moderate and severe pes planus groups (p < 0.0001). The prevalence of anterior knee pain was 4% in both the control and mild pes planus groups, while it was 7% in the moderate and severe pes planus groups (p < 0.0001). CONCLUSION: Moderate and severe pes planus was associated with nearly double the rate of anterior knee pain and intermittent low back pain, while mild pes planus was associated with no higher rate for these problems. Prophylactic measures may be helpful only in those adolescents with moderate and severe pes planus.     

Cadaveric flatfoot model: Ligament attenuation and Achilles tendon overpull

Flatfoot deformity is characterized by loss of the medial longitudinal arch, forefoot abduction, hindfoot eversion, and often Achilles tendon contracture. Our objectives were to validate a cadaveric flatfoot model that involves selective ligament attenuation and to determine if Achilles tendon overpull is associated with increased pes planus severity. We measured the three‐dimensional (3D) orientation of the bones of interest in the unloaded, loaded, and Achilles tendon overpull conditions. A flatfoot model was created by attenuating ligaments involved in the pes planus deformity followed by cyclic axial loading, and bone orientations were acquired in the three conditions. Significant differences seen between normal feet and flat feet were consistent with those seen with the pes planus deformity. The first metatarsal dorsiflexed and abducted relative to the talus. The navicular abducted relative to the talus. The calcaneus everted relative to the tibia. The talus plantar flexed and adducted. Achilles overpull resulted in first metatarsal‐to‐talus dorsiflexion and navicular‐to‐talus abduction. Thus, selective ligament attenuation followed by cyclic axial loading can create a cadaveric flatfoot model consistent with the in vivo deformity. Longitudinal arch depression, hindfoot eversion, talonavicular joint abduction, forefoot abduction, and talar plantar flexion were seen. Simulated Achilles tendon contracture increased the severity of the deformity, particularly in arch depression and forefoot abduction. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1547–1554, 2009     

Weightbearing CT scan of severe flexible pes planus deformities

BACKGROUND: The three-dimensional relationships of the bones in the foot in a flatfoot deformity are difficult to assess with standard radiographs. CT scans demonstrate these relationships but are typically made in a nonweightbearing mode. Our objective was to assess the use of a weightbearing CT apparatus to image the feet in patients with severe flexible pes planus deformities and to better define the anatomical changes that occur. MATERIALS AND METHODS: A specialized device was designed and constructed to simulate weightbearing to the feet during CT examination. Eighteen normal feet and 30 painful severe and flexible pes planus feet were imaged in both the non weightbearing and weightbearing states, set at 50% of body weight. Several measurements of intertarsal relationships were made of the pes planus and normal feet. Navicular floor to skin distance, forefoot arch angle, and subtalar joint subluxation were measured in the coronal plane in both the weightbearing and nonweightbearing states. T-tests were used to analyze measurements of navicular floor to skin distance and forefoot arch angle. RESULTS: The weightbearing device had a significant effect on foot configuration for both normal and pes planus feet (p = 0.0008) and (p < 0.0001) respectively for both floor to skin distance and forefoot arch angle. There was a significant difference between normal feet and pes planus feet with regard to the forefoot arch angle in the nonweightbearing (p = 0.02) and weightbearing states (p = 0.01). Four of the pes planus patients had evidence of subtalar joint subluxation which was more pronounced in the weightbearing state. There was no significant difference between the navicular floor to skin distance in the normal versus pes planus feet in either the non weightbearing (p = 0.05) or the weightbearing states (p = 0.07). CONCLUSION: A device was designed and constructed to apply a weightbearing load equal to that of 50% body weight with minimal to no patient discomfort. The resultant effects on foot configuration were significant, and are useful for assessment of degree of flexible flat foot deformity, thus guiding clinical management. The measure which most significantly differed between pes planus patients and normal volunteers was the forefoot arch angle. Forefoot arch angle may therefore be the most useful measure for the imaging diagnosis of flexible pes planus, and the degree of planus deformity.     

What went wrong in triple arthrodesis? An analysis of failures in 21 patients

Three hundred seven triple arthrodeses were done on 282 patients with rheumatic diseases between 1995 and 1999. Solid and painless fusion was achieved in 261 patients (93%, 286 arthrodeses). Twenty-one arthrodeses (in 21 patients) that failed were analyzed. Fourteen (66%) malunions, six (29%) nonunions, and one (5%) painful foot without malunion or nonunion were found. Of the failed procedures, valgus alignment was present in 13 feet and varus alignment was present in eight feet. The most common cause of failure was a misjudgment in the surgical technique, which occurred in 12 of 21 (57%) patients based on inadequate correction and repositioning of hindfoot deformity. In four (19%) patients, additional ankle destruction and instability was overlooked as a cause of malalignment. Revision triple arthrodesis was successful in 18 of 21 (86%) patients. Triple fusion offers challenges in surgical technique, postoperative treatment, and rehabilitation. Understanding the complexity of the rheumatic hindfoot is important when performing triple arthrodesis in patients with severe deformities manifesting typically as calcaneovalgus and pes planus.     

Impact of pes planus on clinical outcomes of hallux valgus surgery

BackgroundPes planus is associated with hallux valgus development. This study evaluated the impact of pes planus on clinical outcomes following hallux valgus surgery.Methods191 patients underwent Scarf osteotomy for hallux valgus. Pes planus angles including talonavicular coverage angle, lateral talus-first metatarsal angle (Meary’s angle) and lateral talocalcaneal angle were measured. The cohort was stratified into control (0°–4.0°), mild (4.1°–14.9°), moderate (15.0°–30.0°) and severe (> 30.0°) pes planus groups according to Meary’s angle. Clinical outcomes were compared at baseline, 6 months and 24 months.ResultsThere were 78 controls, 95 mild and 18 moderate cases of pes planus. Meary’s angle was independently associated with preoperative hallux valgus angle. Pes planus angles were not associated with pain, AOFAS, SF-36 physical or mental scores. All three groups had similar clinical outcomes and patient satisfaction.ConclusionCompared to patients with neutral foot arches, those with pes planus presented with more severe hallux valgus deformity but had similar clinical outcomes following surgical correction.     

Tarsal coalition resection with pes planovalgus hindfoot reconstruction

Tarsal coalitions often present in young adults as a painful pes planovalgus hindfoot deformity. Resection of moderate and even large coalitions has become accepted as an alternative to arthrodesis. A review of the literature, however, suggests that coalitions with severe preoperative planovalgus malposition treated with resection are associated with continued disability and deformity. The authors believe that malposition contributes to persistent pain and disability after simple coalition resection. The hypothesis is that resection of the coalition with simultaneous hindfoot reconstruction can improve clinical and radiographic outcomes. Seven consecutively treated patients (eight feet) were retrospectively reviewed from the senior author's practice. Clinical exam, American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scores, and radiographic measurements were evaluated after talocalcaneal coalition resection with simultaneous hindfoot reconstruction. All patients were satisfied and would have the same procedure again. All patients were either active students or gainfully employed at last follow-up. Clinical and radiographic hindfoot alignment was corrected reliably. The average increase in medial longitudinal arch height was 8.7 mm. After 2 years the average AOFAS hindfoot score was 88. Most patients had only mildly progressive arthrosis. There were two postoperative complications that resolved (superficial wound breakdown and calf deep vein thrombosis). This hindfoot reconstruction with coalition resection increased motion, reliably corrected malalignment, and improved pain. The authors believe that coalition resection and concomitant hindfoot reconstruction is a better option than resection alone or hindfoot fusion in patients with talocalcaneal coalition and painful pes planovalgus hindfoot deformity. Triple arthrodesis should be reserved as a salvage procedure.     

The Effect of Customized and Silicon Insoles on Mid- and Hindfoot in Adult Flexible Pes Planovalgus

BackgroundFlexible flat foot or pes planovalgus is a common foot deformity, and silicone and customized insole are commonly used as a non-operative treatment modality of flexible planovalgus. However, there are inadequate data and limited evidence available regarding the immediate effects of their use in midfoot and hindfoot of adults. The aim of this study is to quantify and compare the radiological parameters immediately on weightbearing with silicon and customized insoles and without them to assess the effect on midfoot and hindfoot of the flexible planovalgus in adults.MethodsA total number of 11 (8 females and 3 males) subjects with flexible pes planovalgus deformity without any other foot deformity were included in the study. Each patient was assessed three times in a random sequence without and with use of either silicon insoles or customized insole. The radiographic parameters without insole, with silicon insole, and with customized insole conditions were calculated using online available computer software Kinovea.ResultsOne-way ANOVA analysis was performed between groups (without insole, with silicone insole and with customized insole). The hindfoot parameters depicted that calcaneal inclination angle (CIA) was significant increased (P = 0.000) and talar declination angle (TDA) was significantly decreased (P = 0.003) only with the use of customized insole compared to without insole. The midfoot parameters depicted that the first metatarsal angle (FMA) and talonavicular coverage angle (TCA) were significantly lower with customized insole (P = 0.00) as compared to other two groups and significantly lower with silicone insole (P = 0.00) as compared to without insole group.ConclusionThe results imply that the compressibility of the insole material affects the forefoot and hindfoot biomechanics differently. This study concludes that silicone insole affects only the midfoot which bears 45% of bodyweight and customized insole affects both midfoot and more importantly the hindfoot which bears 55% of bodyweight.     

Defining flatfoot.

Pes planus is a term frequently used in describing flatfoot; however, no study has objectively defined flatfoot. We evaluated the single leg stance footprint of 40 feet in 21 people with no history of foot problems, using pressure-sensitive film and a Harris mat. The medial and lateral aspects of the forefoot, midfoot, and hindfoot were assessed. The midfoot was further analyzed by dividing the medial midfoot force by the total midfoot force. The mean medial midfoot force/total midfoot force was 11.1% (SD = 6.5%). Pes planus was defined as the medial midfoot force/total midfoot force > 24.0% (mean + 2 SD). A population associated with pes planus (124 feet in 63 patients with Marfan syndrome) was then evaluated in the same fashion. Although the mean medial midfoot force/total midfoot force was not statistically different (16.0%), a distinct group of patients (25%) had forces that were outside the range of normal midfoot forces.     

Arthroerisis of the subtalar joint

Arthroerisis of the subtalar joint can be a valuable tool for the foot and ankle surgeon in treating flexible pes planus deformity in adults, as well as in children. Whether by itself, or in conjunction with other procedures, such as Achilles tendon lengthening (to allow dorsiflexion to at least neutral), midfoot or hindfoot osteotomies (to correct significant bony deformities), and posterior tibial tendon advancements (with associated symptomatic accessory navicular), arthroerisis can be helpful to correct deformity. When compared with procedures that involve osteotomy or arthrodesis, there is less morbidity to the patient who undergoes arthoerisis during surgery as well as postoperatively. There is no risk of nonunion, less immobilization is usually required, and arthroerisis is technically easy to perform. As with all surgical procedures, proper patient selection is extremely important.     

The developmental anatomy of pes valgo planus

Pes planus or flatfoot becomes a medical problem only when symptoms develop. The mere absence of a well-formed medial longitudinal arch does not necessarily imply pathology. Many apparently "flat feet" demonstrate congruent joints, and the extremities function normally. The size and shape, as well as the angles of declination for the talus or astragulers and the calcaneus or os calcis, are most often determined at the moment of fertilization by the genes of the patients. The zygote or fertilized ovum is a first totipotent. Cell division normally occurs as development proceeds, but the embryo is vulnerable to alterations of the cell cycle. Teratogenic substances can induce death or substantial structural modifications to the developing fetus. The post-World War II tragedy of the medical use of the drug thalidomide in pregnant mothers resulting in amelia is testimony as to how the lower extremity can be adversely affected. Early chromosomal aberrations including duplication, deletion, breakage, inversion, translocation, and mosaicism have been shown to be involved in faulty development of the foot, and there is no reason not to implicate pes valgo planus to these events. Intrauterine development apart from the genetic considerations just mentioned place the fetus under additional jeopardy. Even extraembryonic membranes can form strands of tissue that can entangle the delicate developing foot plate, and calcaneovalgus deformities could conceivably be established. The developing embryo and fetus first demonstrate a blastema that forms limb buds on the ventral caudal aspect. Anlage of the scleroblastema and myoblastema of the prospective leg and foot develop in the presence of nerve trunks. Such nerves are related to the lumbosacral plexus and they are thought to exert inductive developmental influences. Interference with any of these events may be implicated in pedal deformities such as pes valgo planus. This is also true of subsequent morphogenetic events involving embryonic rotations, osteogenesis, and myogenesis. Many pedal deformities have congenital basis and it is clear that pes valgo planus is one of them. Post-natal structural changes further accentuate underlying etiologies. For example, the calcaneus normally exhibits a varus position at birth, but this feature diminishes until the cessation of bone growth. The adult talar neck-calcaneal angle is normally about 24 degrees, representing a 6-degrees reduction from that of 30 degrees, which is demonstrated at birth.(ABSTRACT TRUNCATED AT 400 WORDS)     

Long-term results of in situ subtalar arthrodesis

Isolated subtalar disorders often require subtalar arthrodesis. In this retrospective study of 28 in situ subtalar arthrodeses reviewed with a median follow-up of 56 months (range, 20–115), the authors attempted to detail the outcomes of in situ subtalar fusion, the consequences on adjacent joints and to determine clinical or radiological factors of failure. Clinical evaluation was realised with the AOFAS (American Orthopaedic Foot and Ankle Society) ankle hindfoot score. Radiographic evaluation included assessment of hindfoot alignment, subtalar fusion and arthritic evolution in the adjacent joints. The median functional score was 76.5/94 (range, 36–94). All 28 arthrodeses achieved union. Mild arthritic changes occurred in 43–65% in the different adjacent joints. These changes were not symptomatic. Varus malunion and clinical nonunion seem to be the most important causes of failure.     

Utility outcome assessment of pes planus deformity

Background

Despite being a common condition, there are no objective measures in the literature to reflect the burden of pes planus on affected individuals. Our primary objective was to evaluate this burden by recruiting a sample from the general population using validated utility outcome measures.

The oblique talus deformity. What is it, and what is its clinical significance in the scheme of pronatory deformities?

The advantage for maintaining oblique talus deformity as a diagnostic entity is obvious. It describes a deformity that is somewhere between the severe form of flexible pes planus and congenital convex pes valgus. It is important to recognize that the two subsets (oblique talus deformity with maintenance of the calcaneal inclination angle and oblique talus deformity with reversal of the calcaneal inclination) differ from congenital convex pes valgus by the absence of dislocation of the talonavicular joint. In many cases, the talonavicular joint is merely pushed to its maximum range, and does not even meet the definition of subluxation. Maintaining these distinctions prevents overdiagnosis of congenital convex pes valgus. Additionally, better evaluation of treatment for congenital convex pes valgus results because those cases with better prognosis and better response to nonsurgical intervention are not included in the data for the management of congenital convex pes valgus.     

Relationship between Hallux Valgus and Pes Planus in Adult Patients

This study aimed to determine whether the degree of pes planus was associated with hallux valgus severity and hallux valgus surgery outcomes. A total of 122 feet were retrospectively analyzed after hallux valgus surgery. The hallux valgus angle, inter-metatarsal angle, lateral talo-first metatarsal angle, calcaneal pitch, and talonavicular coverage angle were measured. The Foot and Ankle Outcome Score and Foot Function Index were evaluated. A significant correlation between radiographic parameters of pes planus and hallux valgus severity, radiographic outcomes, Foot and Ankle Outcome Score, and Foot Function Index were not noted. The hallux valgus angle and inter-metatarsal angle changed significantly after the surgery (p < .001 and p < .001, respectively); however, a significant difference was not noted between the pes planus and non-pes planus groups (p = .279 and p = .632, respectively). A significant interaction between the time points and groups was not observed with respect to the hallux valgus angle (p = .311) and inter-metatarsal angle (p = .417). Multivariable logistic regression revealed that none of the radiographic parameters for pes planus affected hallux valgus recurrence. Pes planus in adult patients is not significantly associated with hallux valgus severity and recurrence, radiographic outcomes, or clinical scores.