The Journal of Foot & Ankle Surgery 54 (2015) 449–453
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Influence of a Metatarsus Adductus Foot Type on Plantar Pressures During Walking in Adults Using a Pedobarograph William D. Fishco, DPM, MS, FACFAS 1, 2, Mark B. Ellis, DPM 3, Mark W. Cornwall, PT, PhD 4 1
Faculty, The Podiatry Institute, Decatur, GA Private Practice, Anthem, AZ 3 Postgraduate Third Year Resident, Maricopa Medical Center, Phoenix, AZ 4 Professor of Physical Therapy, Department of Physical Therapy and Athletic Training, Northern Arizona University, Flagstaff, AZ 2
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 3
Metatarsus adductus is a relatively common congenital foot deformity that is often unrecognized at birth. Thus, the adult foot with metatarsus adductus is prone to pathologic entities that have been theorized to result from lateral column overload. We present a descriptive study comparing plantar foot pressure distribution during gait in subjects with and without metatarsus adductus. A total of 65 subjects were recruited for the study: 28 subjects with and 37 subjects without metatarsus adductus. An EMEDÒ pedobarograph was used to collect the data. The analysis of the peak pressure and pressure-time integral in each of the 8 regions of the plantar surface of the foot showed significant (p < .05) differences between each of the regions and a significant (p < .05) interaction effect between the 8 regions and the 2 groups. A series of independent Student’s t tests were therefore performed to determine which of the plantar regions showed a significant difference between the 2 groups. The result of those t tests showed that the peak pressure and pressure-time integral were significantly different (p < .05) between the 2 groups for the “heel,” “lateral midfoot,” and “lateral forefoot.” The results of the present study support the concept that during gait, the adult foot with metatarsus adductus has increased peak plantar pressures on the lateral side of the foot. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: EMEDÒ gait analysis metatarsus adductus peak plantar pressures pedobarographic measures
The current definition of metatarsus adductus (MA) is a uniplanar transverse plane deformity in which the metatarsals are angulated at the Lisfranc joint causing adduction of the forefoot in relation to the midfoot and hindfoot (1,2). Other terms in the medical data have included metatarsus varus (3), metatarsus adductovarus (4), pes adductus, metatarsus supinatus, forefoot adductus, and hooked forefoot (5), less precise terms that include frontal plane deviation (6). The occurrence of MA in live births has been reported on consensus to be 1 to 2 cases per 1000 (7,3) and sometimes as high as 3 per 1000 (1). It is the most common congenital foot deformity in newborns (7), with a male predilection as great as 80% (3). The prevalence is believed to be greater than reported, because recognition is clinician dependent and sensitive to the assessment method (8). Fetal constraint has often been cited as etiologic factor, because of compression of the forefoot with the legs crossed across the body in late gestation, as evidenced by its sparse incidence in premature
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: William D. Fishco, DPM, MS, FACFAS, 41818 North Venture Drive, No. 110, Anthem, AZ 85086. E-mail address: wfi[email protected] (W.D. Fishco).
infants delivered before 30 weeks of gestation (3). Other etiologic hypotheses include abnormal tendon insertions or osseous deformity. MA can be occur independently or with associated other deformities. Also, 1% to 5% of patients with MA will have developmental dysplasia of the hip or acetabular dysplasia (2), and 5% to 10% will have congenital hip dislocation (3,9). Neurologic associations have included spina bifida occulta and spinal muscular atrophy (10). It is a common cause of in-toeing in children and a component of talipes equinovarus; residual MA can persist after conservative or surgical treatment of clubfoot (2). Insufficient appreciation can also lead to greater recurrence of hallux abductovalgus owing to underestimation of the intermetatarsal angle (11). Bleck’s clinical classification of MA focused on severity and flexibility. Extension of the plantar longitudinal heel bisection can define the relationship of the heel to the forefoot. Severity is dictated by the point at which the heel bisector crossed the digits. The grade is considered normal, mild, moderate, or severe if the line bisects the second interdigital space, the third digit, the third interdigital space, or the fourth interdigital space, respectively (12). The clinical examination must also differentiate between rigid and dynamic, with the former an indication of fixed positioning and the latter suggesting an imbalance of the anterior tibial tendon during
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W.D. Fishco et al. / The Journal of Foot & Ankle Surgery 54 (2015) 449–453
Fig. 2. Nontraumatic arthrosis often seen with metatarsus adductus.
Fig. 1. Jones fracture commonly seen with metatarsus adductus.
gait (2). The amount of flexibility of the forefoot is a high prognostic indicator (13). Mild cases often go unnoticed unless symptomatic in later years. One of the most common causes for seeking medical attention is when the child begins to walk with an in-toeing gait (14). Reliable radiographic identification is necessary for the initial diagnosis and classification, monitoring progression, preoperative planning, and evaluation of the outcome. The Sgarlato technique, a modified Sgarlato technique, Engle’s angle, a modified Engle’s angle, the talar-first metatarsal angle, calcaneus-fifth metatarsal angle, Lepow’s angle, and Kilmartin’s angle have all been proposed in published studies for radiographic calculation of the MA angle (8). Most of the published data on the topic of MA has been related to the pediatric condition. However, a paucity of data is available on the clinical manifestations of MA in the adult population. Because the incidence of MA is relatively common, and only the most severe cases are treated at birth, many adults with the unrecognized condition will seek medical care for foot pain. The Jones fracture has often been associated with MA (Fig. 1). It has been postulated that the Jones fracture is ultimately a stress fracture, leading to a frank fracture occurring with overuse or injury (15,16). Studies have also described varus influence of the hindfoot leading to the Jones fracture and MA as a common finding in lateral metatarsal stress fractures (17). An association of increased lateral column overloading of the foot is the principle theory. Simoneau (18) described the center of pressure moving laterally in gait in subjects with MA. No reports describing the plantar pressure distribution during gait in the MA foot type (MAFT) have been published, which was confirmed by searching PubMed and MEDLINE using the key words “metatarsus adductus,” “metatarsus varus,” “plantar pressures,” and “pedobarograph.” Clinical observations and features of the adult MAFT can include a prominent fifth metatarsal base, hallux valgus, and a C-shaped foot print. The senior author (W.D.F.) has observed that the adult MAFT has
the propensity to experience lateral column pain in the region of the fourth and fifth metatarsocuboid joint region and generalized dorsal foot pain in the region of the central metatarsals. Commonly, when the foot is examined, pain to palpation of the dorsal central metatarsals will be present; however, no clinical evidence of a stress fracture, such as a patch of dorsal erythema or edema, or radiographic findings of a fracture will be found. We consider this condition a stress syndrome of the foot. Another clinical manifestation of MA in the adult foot includes nontraumatic arthrosis of the second and third tarsometatarsal joints (Fig. 2). The main goal of the present study was to describe the plantar foot pressure distribution during gait in adults with the MAFT. This information could help explain why the MAFT is predisposed to certain pathologic conditions. Patients and Methods A total of 65 subjects (21 [32.3%] males, 44 [67.7%] females) were included in the present study. The subjects were evaluated clinically by a licensed podiatrist (W.D.F.) to determine whether the subject had MA using plain film radiographic measurements. Of the 65 subjects, 28 (11 males, 17 females) were classified as having the MAFT and 37 (10 males, 27 females) were classified as not having the MAFT (control group). The demographic features of the 2 groups are listed in Table 1. The subjects were excluded from the study if they had had previous foot or ankle surgery, had compound deformities such as tibial vacuum or valgum, skew foot, pes cavus deformity, or if they had pain or dysfunction in their feet or lower extremities that would alter their ability to ambulate normally. The subjects were examined during gait to assess for obvious signs of an antalgic gait or limping. Moreover, the subjects were asked whether they would be able to walk on the test runway without out pain or favoritism to an extremity. Patients with a diagnosis of inflammatory conditions such as a sprain, strain, plantar fasciitis, tendinitis, capsulitis, periostitis, and fracture were excluded. During recruitment, 61 patients were identified as having the MAFT and 33 were excluded. The institutional review board at Northern Arizona University approved the present study, Table 1 Demographic information (N ¼ 65) Variable
Metatarsus Adductus Group
Age (y) Height (cm) Weight (kg) BMI (kg/m2) Metatarsus adductus angle ( )
43.3 168.1 78.7 27.74 21.9
16.7 10.9 19.9 6.0 4.0
Abbreviation: BMI, body mass index. Data presented as mean standard deviation.
Control Group 43.0 168.5 74.2 26.05 11.5
17.3 9.9 16.6 4.9 5.2
W.D. Fishco et al. / The Journal of Foot & Ankle Surgery 54 (2015) 449–453
and all subjects read and signed an informed consent form before participating in the study. After the patients had provided written informed consent, the subjects’ height and weight were recorded, and 3 standard weightbearing foot radiographic views were obtained from each limb. The MA angle was measured using the modified Sgarlato method (6). Radiographs were processed using TigerView Digital Imaging Software (Televere Systems, Janesville, WI). A measurement tool within the software was used to obtain the angular data. Patients with a MA angle of 15.0 were included in the MAFT group. Each radiographic angle was measured 3 times and averaged by the same investigator (M.B.E.). The subjects were then asked to walk barefoot 3 times over an EMEDÒ pedobarograph (Novel, Munich, Germany) using the 2-step method. This method has been shown to be reliable and valid (19,20). Three types of analyses were conducted with the resulting plantar pressure data using the Novel analysis software (Novel, Munich, Germany). Tests of statistical significance was performed using a series of independent t tests or 2-way analysis of variance tests to determine whether differences were present between the 2 groups for any of the measured plantar pressure variables. An a level of 0.05 was used for all the tests as the criterion for statistical significance. The overall shape of the subject’s plantar footprint was first analyzed using the EMEDÒ “geometry” analysis program (Novel). This analysis calculates the number of angles from the plantar pressure plot that are indicative of the plantar shape. These angles are the “long plantar angle,” “lateral plantar angle,” “medial plantar angle,” “subarch angle,” “forefoot angle,” and “hallux angle” (Fig. 3). The statistical significance between the 2 groups of subjects for each of these variables was determined using an independent t test. The medial-lateral displacement of the subject’s gait line during walking was analyzed using “Gaitline” analysis software (Novel GmbH, Munich, Germany). This analysis calculates the plantar surface area on the medial and lateral sides of the person’s gait line. It also calculates a ratio of this medial and lateral area. Again, statistical significance between the two groups of subjects was determined using an independent t test. The final analysis involved dividing the plantar surface of the foot into 8 regions according to the fixed percentages of the width and length of the foot. These regions
Fig. 3. The plantar angles calculated using the Novel “geometry” analysis software.
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were (1) heel, (2) medial midfoot, (3) lateral midfoot, (4) medial forefoot, (5) central forefoot, (6) lateral forefoot, (7) hallux, and (8) toes (Fig. 4). The magnitude of pressure or the pressure-time integral was then calculated for each of the regions. The pressuretime integral was defined by the area under the curve of pressure and time. It is valuable because it accounts for both variables. For example, the pressure might not be excessively high; however, it if it is applied for an extended period, it could be detrimental. A 2-way mixed-effect analysis of variance test was used to determine whether differences were present in either pressure or the pressure-time integral among the 8 different plantar regions, between the 2 different groups, and whether an interaction was present between the regions and groups. If a statistically significant interaction effect was found, a series of independent t tests were performed to determine whether differences existed between the 2 groups for a particular plantar region.
Results No statistically significant difference was found between the 2 groups of subjects for any of the demographic variables (Table 1). However, a statistically significant difference was found between the 2 groups of subjects for the MA angle, indicating that the clinical evaluation (including confirmatory radiographs) was able to correctly identify those with MA. The statistical analysis of the plantar angles measured from the plantar pressure patterns recorded during walking showed that the medial plantar, lateral plantar, and long plantar angles were significantly different (p < .05) between the 2 groups. None of the other angles, however, were significantly different (Table 2). That these angles were significantly different, but the forefoot and heel width
Fig. 4. Illustration of the 8 regions of the plantar surface of the foot used in the analysis of the peak pressure and pressure-time integral analysis in each region.
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Table 2 Plantar angles calculated using the Novel “geometry” analysis software Variable
MAFT Group (n ¼ 28)
Long plantar angle ( ) Lateral plantar angle ( ) Medial plantar angle ( ) Subarch angle ( ) Forefoot angle ( ) Hallux angle ( ) Forefoot width (cm) Heel width (cm)
16.5 8.3 8.3 105.6 114.2 4.5 9.8 5.5
1.4 0.7 0.7 11.5 3.5 6.9 0.7 0.6
Control Group (n ¼ 37) 15.7* 7.8* 7.8* 107.6 113.6 3.2 9.5 5.4
2.2 1.1 1.1 1.1 2.8 6.3 0.7 0.6)
Abbreviation: MAFT, metatarsus adductus foot type. Data presented as mean standard deviation. * Statistically significantly different (p < .05).
were not would indicate that those with the MAFT have a wider forefoot relative to the heel compared with those with a normal foot type. This most likely results directly from the adducted position of the first metatarsal in those with the MAFT; however, its magnitude is not sufficient to result in a significantly wider forefoot in this group of subjects. The p value for the forefoot width was .054, indicating that with a slightly larger sample size, the differences in the forefoot width would have been statistically significant. The analysis of the area on the medial and lateral sides of the gait line during walking showed no statistically significant difference between the 2 groups of subjects. As such, the gait line for those with the MAFT did not appear altered (Table 3). The analysis of the peak pressure and pressure-time integral in each of the 8 regions of the plantar surface of the foot showed that a statistically significant (p < .05) difference was present among each of the regions and a significant (p < .05) interaction effect among the 8 regions and the 2 groups of subjects. A series of independent t tests were, therefore, performed to determine which of the plantar regions showed a significant difference between the 2 groups. The result of those t tests showed that the peak pressure and pressure-time integral was significantly different (p < .05) between the 2 groups for the “heel,” the “lateral midfoot,” and the “lateral forefoot” (Figs. 5 and 6). Discussion A descriptive study of plantar pressures of the MAFT has been presented. Statistically significant greater peak plantar pressures and pressure-time integrals were found in the region of the heel, lateral midfoot, and lateral forefoot in the MAFT compared with those subjects without MA. It has been theorized that the MAFT leads to lateral column overload, which leads to pain syndromes on the dorsolateral foot. The results of the present study are in accordance with this theory, because increased pressures were noted on the lateral border of foot. Because the adult MAFT is a common finding in the clinical setting, perhaps better screening of newborns should be performed. In addition, it might be prudent to be more aggressive in the treatment of the younger population with MA owing to the treatment challenges that face adults with lateral column overload conditions.
Fig. 5. Analysis of peak pressure in each of the 8 regions of the plantar surface of the foot during walking.
Moreover, from a surgical standpoint, large hallux valgus deformities have been commonly seen, for which few options are available without a pan-metatarsal osteotomy procedure (Fig. 7). An adult with a Z-foot deformity is yet another example of a surgical challenge, because when the flat foot component is addressed, the MA worsens. We recognize that the present study had some serious limitations, including a relatively small sample size. Also, some of the subjects might have had mild pain, because they were seen in a clinic setting for care, and, most importantly, they might have had other mechanical or structural influences that were not assessed but might have affected their plantar pressures. Additional research should be undertaken, including a complete biomechanical examination to assess for ankle equinus, total subtalar joint range of motion, frontal plane deformities of the forefoot, calcaneus, and tibia, and limb length discrepancy. Although subjects with grossly visible deformities were excluded, mild or subtle conditions of ankle equinus, limb length discrepancy, tibial rotation, hallux valgus, hammertoes, and other frontal plane deformities could have been present that could have altered the plantar pressures measured. Our study did, however, demonstrate a significant change in plantar pressures between
Table 3 Force-time integral on the lateral and medial sides of the gait line during walking Force-Time Integral (N-s)
MAFT Group (n ¼ 28)
Laterally Medially Difference Ratio
248.4 213.1 35.4 0.06
77.5 61.0 50.0 0.08
Abbreviation: MAFT, metatarsus adductus foot type. Data presented as mean standard deviation.
Control Group (n ¼ 35) 255.2 224.9 30.3 0.07
76.8 66.5 41.2 0.09 Fig. 6. Analysis of the pressure-time integral in each of the 8 regions of the plantar surface of the foot during walking.
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pressures. Moreover, it would of great importance to clinicians to be able to determine which parameters might be a common denominator contributing to pain syndromes in the MAFT. An analysis of the degree of MA, arch height, other varus influences of the foot, and arch height stiffness should also be considered. References
Fig. 7. Severe hallux valgus deformity with underlying metatarsus adductus. Surgical correction can be challenging and often requires a pan-metatarsal osteotomy procedure.
subjects with MA and those without using the parameter of a weightbearing anteroposterior radiograph. Additional studies are necessary to analyze other structural conditions and biomechanical influences that can affect the MAFT plantar
1. Dawoodi AIS, Perera A. Radiological assessment of metatarsus adductus. Foot Ankle Surg 18:1–8, 2012. 2. Kelly DM. Congenital anomalies of the lower extremity. In: Campbell’s Operative Orthopaedics, ed 4, pp. 980–1078, edited by ST Canale, JH Beaty, Elsevier Mosby, Philadelphia, 2013. 3. Graham JM Jr, Graham JM. Smith’s Recognizable Patterns of Human Deformation, ed 3, WB Saunders, Philadelphia, 2007. 4. Lloyd-Roberts GC. Ball and socket ankle joint in metatarsus adductus varus (Sshaped or serpentine foot). Lloyd-Roberts. J Bone Joint Surg Br 55:193–196, 1973. 5. Rushforth C. The natural history of hooked forefoot. J Bone Joint Surg Br 60:530– 532, 1978. 6. Castellano BD, Smith TF. Metatarsus Adductus. The Podiatry Institute Update 1989, The Podiatry Institute, Decatur, GA, 1989. 7. Williams CM, James AM, Tran T. Metatarsus adductus: development of a nonsurgical treatment pathway. J Paediatr Child Health 49:E428–E433, 2013. 8. Dawoodi AIS, Perera A. Reliability of metatarsus adductus angle and correlation with hallux valgus. Foot Ankle Surg 18:180–186, 2012. 9. Ladino Torres MF. Developmental dysplasia of the hip. Ultrasound Clin 4:445–455, 2009. 10. Fixsen JA. The foot. In: Children’s Orthopaedics and Fractures, pp. 523–539, edited by M Benson, J Fixsen, M MacNicol, K Parsch, Springer London, London, 2009. 11. Belczyk R, Stapleton JJ, Grossman JP, Zqonis T. Complications and revisional hallux valgus surgery. Clin Podiatr Med Surg 26:475–484, 2009. 12. Bleck EE. Metatarsus adductus: classification and relationship to outcomes of treatment. J Pediatr Orthop 3:2–9, 1983. 13. Nemeth B. The diagnosis and management of common childhood orthopedic disorders. Curr Probl Pediatr Adolesc Health Care 41:2–28, 2011. 14. Jacobs B. Toe walking, flat feet and bow legs, in-toeing and out-toeing: practice points. Paediatr Child Health 20:221–224, 2010. 15. Kavanaugh JH, Brower TD, Mann RV. The Jones fracture revisited. J Bone Joint Surg 60:776–782, 1978. 16. Yoho RM, Carrington S, Dix B, Vardaxis V. The association of metatarsus adductus to the proximal fifth metatarsal Jones fracture. J Foot Ankle Surg 51:739–742, 2012. 17. Raikin SM, Nicholas S, Ratigan B. The association of a varus hindfoot and fracture of the fifth metatarsal metaphyseal-diaphyseal junction: the Jones fracture. Am J Sports Med 36:1367–1372, 2008. 18. Simoneau G. Kinesiology of walking. In: Kinesiology of the Musculoskeletal System: Foundations for Physical Rehabilitation, pp. 523–551, edited by DA Neuman, Mosby, St Louis, 2002. 19. McPoil TG, Cornwall MW, Dupuis L, Cornwell M. Variability of plantar pressure data: a comparison of the two-step method and midgait methods. J Am Podiatr Med Assoc 89:495–501, 1999. 20. Ramachandra P, Maiya AG, Kumar P. Test-retest reliability of the Win-Track platform in analyzing the gait parameters and plantar pressures during barefoot walking in healthy adults. Foot Ankle Spec 5:306–312, 2012.
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery journal homepage: www.jfas.org
Influence of a Metatarsus Adductus Foot Type on Plantar Pressures During Walking in Adults Using a Pedobarograph William D. Fishco, DPM, MS, FACFAS 1, 2, Mark B. Ellis, DPM 3, Mark W. Cornwall, PT, PhD 4 1
Faculty, The Podiatry Institute, Decatur, GA Private Practice, Anthem, AZ 3 Postgraduate Third Year Resident, Maricopa Medical Center, Phoenix, AZ 4 Professor of Physical Therapy, Department of Physical Therapy and Athletic Training, Northern Arizona University, Flagstaff, AZ 2
a r t i c l e i n f o
a b s t r a c t
Level of Clinical Evidence: 3
Metatarsus adductus is a relatively common congenital foot deformity that is often unrecognized at birth. Thus, the adult foot with metatarsus adductus is prone to pathologic entities that have been theorized to result from lateral column overload. We present a descriptive study comparing plantar foot pressure distribution during gait in subjects with and without metatarsus adductus. A total of 65 subjects were recruited for the study: 28 subjects with and 37 subjects without metatarsus adductus. An EMEDÒ pedobarograph was used to collect the data. The analysis of the peak pressure and pressure-time integral in each of the 8 regions of the plantar surface of the foot showed significant (p < .05) differences between each of the regions and a significant (p < .05) interaction effect between the 8 regions and the 2 groups. A series of independent Student’s t tests were therefore performed to determine which of the plantar regions showed a significant difference between the 2 groups. The result of those t tests showed that the peak pressure and pressure-time integral were significantly different (p < .05) between the 2 groups for the “heel,” “lateral midfoot,” and “lateral forefoot.” The results of the present study support the concept that during gait, the adult foot with metatarsus adductus has increased peak plantar pressures on the lateral side of the foot. Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved.
Keywords: EMEDÒ gait analysis metatarsus adductus peak plantar pressures pedobarographic measures
The current definition of metatarsus adductus (MA) is a uniplanar transverse plane deformity in which the metatarsals are angulated at the Lisfranc joint causing adduction of the forefoot in relation to the midfoot and hindfoot (1,2). Other terms in the medical data have included metatarsus varus (3), metatarsus adductovarus (4), pes adductus, metatarsus supinatus, forefoot adductus, and hooked forefoot (5), less precise terms that include frontal plane deviation (6). The occurrence of MA in live births has been reported on consensus to be 1 to 2 cases per 1000 (7,3) and sometimes as high as 3 per 1000 (1). It is the most common congenital foot deformity in newborns (7), with a male predilection as great as 80% (3). The prevalence is believed to be greater than reported, because recognition is clinician dependent and sensitive to the assessment method (8). Fetal constraint has often been cited as etiologic factor, because of compression of the forefoot with the legs crossed across the body in late gestation, as evidenced by its sparse incidence in premature
Financial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: William D. Fishco, DPM, MS, FACFAS, 41818 North Venture Drive, No. 110, Anthem, AZ 85086. E-mail address: wfi[email protected] (W.D. Fishco).
infants delivered before 30 weeks of gestation (3). Other etiologic hypotheses include abnormal tendon insertions or osseous deformity. MA can be occur independently or with associated other deformities. Also, 1% to 5% of patients with MA will have developmental dysplasia of the hip or acetabular dysplasia (2), and 5% to 10% will have congenital hip dislocation (3,9). Neurologic associations have included spina bifida occulta and spinal muscular atrophy (10). It is a common cause of in-toeing in children and a component of talipes equinovarus; residual MA can persist after conservative or surgical treatment of clubfoot (2). Insufficient appreciation can also lead to greater recurrence of hallux abductovalgus owing to underestimation of the intermetatarsal angle (11). Bleck’s clinical classification of MA focused on severity and flexibility. Extension of the plantar longitudinal heel bisection can define the relationship of the heel to the forefoot. Severity is dictated by the point at which the heel bisector crossed the digits. The grade is considered normal, mild, moderate, or severe if the line bisects the second interdigital space, the third digit, the third interdigital space, or the fourth interdigital space, respectively (12). The clinical examination must also differentiate between rigid and dynamic, with the former an indication of fixed positioning and the latter suggesting an imbalance of the anterior tibial tendon during
1067-2516/$ - see front matter Ó 2015 by the American College of Foot and Ankle Surgeons. All rights reserved. http://dx.doi.org/10.1053/j.jfas.2014.11.007
450
W.D. Fishco et al. / The Journal of Foot & Ankle Surgery 54 (2015) 449–453
Fig. 2. Nontraumatic arthrosis often seen with metatarsus adductus.
Fig. 1. Jones fracture commonly seen with metatarsus adductus.
gait (2). The amount of flexibility of the forefoot is a high prognostic indicator (13). Mild cases often go unnoticed unless symptomatic in later years. One of the most common causes for seeking medical attention is when the child begins to walk with an in-toeing gait (14). Reliable radiographic identification is necessary for the initial diagnosis and classification, monitoring progression, preoperative planning, and evaluation of the outcome. The Sgarlato technique, a modified Sgarlato technique, Engle’s angle, a modified Engle’s angle, the talar-first metatarsal angle, calcaneus-fifth metatarsal angle, Lepow’s angle, and Kilmartin’s angle have all been proposed in published studies for radiographic calculation of the MA angle (8). Most of the published data on the topic of MA has been related to the pediatric condition. However, a paucity of data is available on the clinical manifestations of MA in the adult population. Because the incidence of MA is relatively common, and only the most severe cases are treated at birth, many adults with the unrecognized condition will seek medical care for foot pain. The Jones fracture has often been associated with MA (Fig. 1). It has been postulated that the Jones fracture is ultimately a stress fracture, leading to a frank fracture occurring with overuse or injury (15,16). Studies have also described varus influence of the hindfoot leading to the Jones fracture and MA as a common finding in lateral metatarsal stress fractures (17). An association of increased lateral column overloading of the foot is the principle theory. Simoneau (18) described the center of pressure moving laterally in gait in subjects with MA. No reports describing the plantar pressure distribution during gait in the MA foot type (MAFT) have been published, which was confirmed by searching PubMed and MEDLINE using the key words “metatarsus adductus,” “metatarsus varus,” “plantar pressures,” and “pedobarograph.” Clinical observations and features of the adult MAFT can include a prominent fifth metatarsal base, hallux valgus, and a C-shaped foot print. The senior author (W.D.F.) has observed that the adult MAFT has
the propensity to experience lateral column pain in the region of the fourth and fifth metatarsocuboid joint region and generalized dorsal foot pain in the region of the central metatarsals. Commonly, when the foot is examined, pain to palpation of the dorsal central metatarsals will be present; however, no clinical evidence of a stress fracture, such as a patch of dorsal erythema or edema, or radiographic findings of a fracture will be found. We consider this condition a stress syndrome of the foot. Another clinical manifestation of MA in the adult foot includes nontraumatic arthrosis of the second and third tarsometatarsal joints (Fig. 2). The main goal of the present study was to describe the plantar foot pressure distribution during gait in adults with the MAFT. This information could help explain why the MAFT is predisposed to certain pathologic conditions. Patients and Methods A total of 65 subjects (21 [32.3%] males, 44 [67.7%] females) were included in the present study. The subjects were evaluated clinically by a licensed podiatrist (W.D.F.) to determine whether the subject had MA using plain film radiographic measurements. Of the 65 subjects, 28 (11 males, 17 females) were classified as having the MAFT and 37 (10 males, 27 females) were classified as not having the MAFT (control group). The demographic features of the 2 groups are listed in Table 1. The subjects were excluded from the study if they had had previous foot or ankle surgery, had compound deformities such as tibial vacuum or valgum, skew foot, pes cavus deformity, or if they had pain or dysfunction in their feet or lower extremities that would alter their ability to ambulate normally. The subjects were examined during gait to assess for obvious signs of an antalgic gait or limping. Moreover, the subjects were asked whether they would be able to walk on the test runway without out pain or favoritism to an extremity. Patients with a diagnosis of inflammatory conditions such as a sprain, strain, plantar fasciitis, tendinitis, capsulitis, periostitis, and fracture were excluded. During recruitment, 61 patients were identified as having the MAFT and 33 were excluded. The institutional review board at Northern Arizona University approved the present study, Table 1 Demographic information (N ¼ 65) Variable
Metatarsus Adductus Group
Age (y) Height (cm) Weight (kg) BMI (kg/m2) Metatarsus adductus angle ( )
43.3 168.1 78.7 27.74 21.9
16.7 10.9 19.9 6.0 4.0
Abbreviation: BMI, body mass index. Data presented as mean standard deviation.
Control Group 43.0 168.5 74.2 26.05 11.5
17.3 9.9 16.6 4.9 5.2
W.D. Fishco et al. / The Journal of Foot & Ankle Surgery 54 (2015) 449–453
and all subjects read and signed an informed consent form before participating in the study. After the patients had provided written informed consent, the subjects’ height and weight were recorded, and 3 standard weightbearing foot radiographic views were obtained from each limb. The MA angle was measured using the modified Sgarlato method (6). Radiographs were processed using TigerView Digital Imaging Software (Televere Systems, Janesville, WI). A measurement tool within the software was used to obtain the angular data. Patients with a MA angle of 15.0 were included in the MAFT group. Each radiographic angle was measured 3 times and averaged by the same investigator (M.B.E.). The subjects were then asked to walk barefoot 3 times over an EMEDÒ pedobarograph (Novel, Munich, Germany) using the 2-step method. This method has been shown to be reliable and valid (19,20). Three types of analyses were conducted with the resulting plantar pressure data using the Novel analysis software (Novel, Munich, Germany). Tests of statistical significance was performed using a series of independent t tests or 2-way analysis of variance tests to determine whether differences were present between the 2 groups for any of the measured plantar pressure variables. An a level of 0.05 was used for all the tests as the criterion for statistical significance. The overall shape of the subject’s plantar footprint was first analyzed using the EMEDÒ “geometry” analysis program (Novel). This analysis calculates the number of angles from the plantar pressure plot that are indicative of the plantar shape. These angles are the “long plantar angle,” “lateral plantar angle,” “medial plantar angle,” “subarch angle,” “forefoot angle,” and “hallux angle” (Fig. 3). The statistical significance between the 2 groups of subjects for each of these variables was determined using an independent t test. The medial-lateral displacement of the subject’s gait line during walking was analyzed using “Gaitline” analysis software (Novel GmbH, Munich, Germany). This analysis calculates the plantar surface area on the medial and lateral sides of the person’s gait line. It also calculates a ratio of this medial and lateral area. Again, statistical significance between the two groups of subjects was determined using an independent t test. The final analysis involved dividing the plantar surface of the foot into 8 regions according to the fixed percentages of the width and length of the foot. These regions
Fig. 3. The plantar angles calculated using the Novel “geometry” analysis software.
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were (1) heel, (2) medial midfoot, (3) lateral midfoot, (4) medial forefoot, (5) central forefoot, (6) lateral forefoot, (7) hallux, and (8) toes (Fig. 4). The magnitude of pressure or the pressure-time integral was then calculated for each of the regions. The pressuretime integral was defined by the area under the curve of pressure and time. It is valuable because it accounts for both variables. For example, the pressure might not be excessively high; however, it if it is applied for an extended period, it could be detrimental. A 2-way mixed-effect analysis of variance test was used to determine whether differences were present in either pressure or the pressure-time integral among the 8 different plantar regions, between the 2 different groups, and whether an interaction was present between the regions and groups. If a statistically significant interaction effect was found, a series of independent t tests were performed to determine whether differences existed between the 2 groups for a particular plantar region.
Results No statistically significant difference was found between the 2 groups of subjects for any of the demographic variables (Table 1). However, a statistically significant difference was found between the 2 groups of subjects for the MA angle, indicating that the clinical evaluation (including confirmatory radiographs) was able to correctly identify those with MA. The statistical analysis of the plantar angles measured from the plantar pressure patterns recorded during walking showed that the medial plantar, lateral plantar, and long plantar angles were significantly different (p < .05) between the 2 groups. None of the other angles, however, were significantly different (Table 2). That these angles were significantly different, but the forefoot and heel width
Fig. 4. Illustration of the 8 regions of the plantar surface of the foot used in the analysis of the peak pressure and pressure-time integral analysis in each region.
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Table 2 Plantar angles calculated using the Novel “geometry” analysis software Variable
MAFT Group (n ¼ 28)
Long plantar angle ( ) Lateral plantar angle ( ) Medial plantar angle ( ) Subarch angle ( ) Forefoot angle ( ) Hallux angle ( ) Forefoot width (cm) Heel width (cm)
16.5 8.3 8.3 105.6 114.2 4.5 9.8 5.5
1.4 0.7 0.7 11.5 3.5 6.9 0.7 0.6
Control Group (n ¼ 37) 15.7* 7.8* 7.8* 107.6 113.6 3.2 9.5 5.4
2.2 1.1 1.1 1.1 2.8 6.3 0.7 0.6)
Abbreviation: MAFT, metatarsus adductus foot type. Data presented as mean standard deviation. * Statistically significantly different (p < .05).
were not would indicate that those with the MAFT have a wider forefoot relative to the heel compared with those with a normal foot type. This most likely results directly from the adducted position of the first metatarsal in those with the MAFT; however, its magnitude is not sufficient to result in a significantly wider forefoot in this group of subjects. The p value for the forefoot width was .054, indicating that with a slightly larger sample size, the differences in the forefoot width would have been statistically significant. The analysis of the area on the medial and lateral sides of the gait line during walking showed no statistically significant difference between the 2 groups of subjects. As such, the gait line for those with the MAFT did not appear altered (Table 3). The analysis of the peak pressure and pressure-time integral in each of the 8 regions of the plantar surface of the foot showed that a statistically significant (p < .05) difference was present among each of the regions and a significant (p < .05) interaction effect among the 8 regions and the 2 groups of subjects. A series of independent t tests were, therefore, performed to determine which of the plantar regions showed a significant difference between the 2 groups. The result of those t tests showed that the peak pressure and pressure-time integral was significantly different (p < .05) between the 2 groups for the “heel,” the “lateral midfoot,” and the “lateral forefoot” (Figs. 5 and 6). Discussion A descriptive study of plantar pressures of the MAFT has been presented. Statistically significant greater peak plantar pressures and pressure-time integrals were found in the region of the heel, lateral midfoot, and lateral forefoot in the MAFT compared with those subjects without MA. It has been theorized that the MAFT leads to lateral column overload, which leads to pain syndromes on the dorsolateral foot. The results of the present study are in accordance with this theory, because increased pressures were noted on the lateral border of foot. Because the adult MAFT is a common finding in the clinical setting, perhaps better screening of newborns should be performed. In addition, it might be prudent to be more aggressive in the treatment of the younger population with MA owing to the treatment challenges that face adults with lateral column overload conditions.
Fig. 5. Analysis of peak pressure in each of the 8 regions of the plantar surface of the foot during walking.
Moreover, from a surgical standpoint, large hallux valgus deformities have been commonly seen, for which few options are available without a pan-metatarsal osteotomy procedure (Fig. 7). An adult with a Z-foot deformity is yet another example of a surgical challenge, because when the flat foot component is addressed, the MA worsens. We recognize that the present study had some serious limitations, including a relatively small sample size. Also, some of the subjects might have had mild pain, because they were seen in a clinic setting for care, and, most importantly, they might have had other mechanical or structural influences that were not assessed but might have affected their plantar pressures. Additional research should be undertaken, including a complete biomechanical examination to assess for ankle equinus, total subtalar joint range of motion, frontal plane deformities of the forefoot, calcaneus, and tibia, and limb length discrepancy. Although subjects with grossly visible deformities were excluded, mild or subtle conditions of ankle equinus, limb length discrepancy, tibial rotation, hallux valgus, hammertoes, and other frontal plane deformities could have been present that could have altered the plantar pressures measured. Our study did, however, demonstrate a significant change in plantar pressures between
Table 3 Force-time integral on the lateral and medial sides of the gait line during walking Force-Time Integral (N-s)
MAFT Group (n ¼ 28)
Laterally Medially Difference Ratio
248.4 213.1 35.4 0.06
77.5 61.0 50.0 0.08
Abbreviation: MAFT, metatarsus adductus foot type. Data presented as mean standard deviation.
Control Group (n ¼ 35) 255.2 224.9 30.3 0.07
76.8 66.5 41.2 0.09 Fig. 6. Analysis of the pressure-time integral in each of the 8 regions of the plantar surface of the foot during walking.
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pressures. Moreover, it would of great importance to clinicians to be able to determine which parameters might be a common denominator contributing to pain syndromes in the MAFT. An analysis of the degree of MA, arch height, other varus influences of the foot, and arch height stiffness should also be considered. References
Fig. 7. Severe hallux valgus deformity with underlying metatarsus adductus. Surgical correction can be challenging and often requires a pan-metatarsal osteotomy procedure.
subjects with MA and those without using the parameter of a weightbearing anteroposterior radiograph. Additional studies are necessary to analyze other structural conditions and biomechanical influences that can affect the MAFT plantar
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