G Model
GAIPOS-4072; No. of Pages 4 Gait & Posture xxx (2013) xxx–xxx
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Comparison of plantar pressures and contact area between normal and cavus foot Lourdes M. Ferna´ndez-Seguı´n a,1,*, Juan Antonio Diaz Mancha a,1, Raquel Sa´nchez Rodrı´guez b,2, Elena Escamilla Martı´nez b,2, Beatriz Go´mez Martı´n b,2, Javier Ramos Ortega c,1 a
Physiotherapy Department, University of Seville, Spain Nursing Department, University of Extremadura, Spain c Podology Department, University of Seville, Spain b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 4 February 2013 Received in revised form 13 October 2013 Accepted 21 October 2013
Background: In pes cavus, the medial longitudinal arch elevation reduces the contact surface area and consequently increases the corresponding plantar pressure measurements. This poor distribution of loads may produce associated pathology and pain in this or other areas of the body. Normal reference values need to be established in order to determine which patterns are prone to pathology. Objectives: To compare the plantar pressures and weight-bearing surface in a population with pes cavus to a population with neutral feet. Method: The sample comprised 68 adults, 34 with pes cavus and 34 with neutral feet. The Footscan USB Gait Clinical System1 was used as a platform to measure the total contact area and plantar pressure under the forefoot, midfoot, hindfoot, each metatarsal head, and the overall metatarsal area. A statistical analysis of the data was performed using Student’s t-test for independent samples. Results: The pes cavus subjects showed a significant reduction in their weight-bearing area [neutral feet: 165.04 (20.68) cm2; pes cavus: 118.26 (30.31) cm2; p < 0.001] and significantly increased pressures under all zones of the forefoot except the fifth metatarsal [metatarsal pressure: in neutral feet 503,797 (9.32) kPa; in pes cavus 656.12 (22.39) kPa; p < 0.001]. Conclusions: Compared to neutral feet, pes cavus feet show a reduction in total contact surface and the load under the first toe. A significant increase is present in the load under the metatarsal areas, but the relative distribution of this load is similar in both groups. ß 2013 Elsevier B.V. All rights reserved.
Keywords: Cavus foot Normal foot Plantar pressure Contact surface Baropodometry
1. Introduction Foot pain is highly prevalent and may be associated with foot deformities, leg pain and lower back pain [1]. Estimates indicate that about 10–15% of the general population have cavus feet [2,3] and 60% of these have suffered pain, which is presumed to be related to excessive pressure, at some time in their lives [4,5]. The main feature of pes cavus, in so far as plantar pressure is concerned, is that the contact zone of the midfoot is reduced compared to neutral feet, resulting in increased pressure in this
* Corresponding author at: Facultad de Enfermerı´a, Fisioterapia y Podologı´a, Centro Docente de Fisioterapia y Podologı´a, c/Avicena s/n, 41009 Sevilla, Spain. Tel.: +34 954486505. E-mail address: [email protected] (L.M. Ferna´ndez-Seguı´n). 1 Facultad de Enfermerı´a, Fisioterapia y Podologı´a, Centro Docente de Fisioterapia y Podologı´a, c/Avicena s/n, 41009 Sevilla, Spain. 2 Centro Universitario, Avenida Virgen del Puerto, numero 2, 10600 Plasencia, Ca´ceres, Spain.
area. This increased pressure may lead to the occurrence of foot pathologies and pain. However, in order to determine whether or not this is a reasonable assumption, a comparison with the baropodometry of neutral feet is required, so as to observe whether or not there are large differences in the recorded pressure values. In reviewing the literature, a lack of agreement was found regarding plantar pressure distribution in neutral feet. Some suggest that the loads are evenly distributed between the forefoot and the hindfoot [6], others that the ratio is three parts on the forefoot and five parts on the hindfoot [7], and yet others describe a variety of comfortable standing positions with the heel bearing between one and three times as much load as the forefoot [8]. Recent studies with current baropodometric platforms agree that, in normal feet, the pressure is slightly higher on the heel than on the forefoot, although without reaching the margins described historically [9,10]. There is also general agreement that, in the forefoot, the second and third metatarsal heads are the ones subjected to the greatest loads [11–13].
0966-6362/$ – see front matter ß 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gaitpost.2013.10.018
Please cite this article in press as: Ferna´ndez-Seguı´n LM, et al. Comparison of plantar pressures and contact area between normal and cavus foot. Gait Posture (2013), http://dx.doi.org/10.1016/j.gaitpost.2013.10.018
G Model
GAIPOS-4072; No. of Pages 4 L.M. Ferna´ndez-Seguı´n et al. / Gait & Posture xxx (2013) xxx–xxx
2
In pes cavus, the zone under the greatest load is the forefoot [4,5,14,15]. However, the distribution of this load beneath the forefoot has not yet been investigated. Therefore, the aim of this study was to measure and compare the plantar pressure in two populations; one comprising subjects classified as pes cavus and the other involving individuals with a neutral foot posture, paying particular attention to the metatarsal zone. 2. Methods We conducted a descriptive study based on a cross-sectional series of cases divided into two groups. The first stage involved collecting baropodometric measurements in a group of subjects with pes cavus. This group was comprised of 34 subjects with a mean age of 24.21 (5.18) years, and a BMI of 22.10 (2.64) kg/m2. The diagnosis of pes cavus was defined radiologically as an internal Bartani Costa angle less than 125 [16]. These measurements were undertaken at the Clinical Podiatry Area of the University of Seville. The second stage of the study was devoted to performing the corresponding baropodometric measurements in subjects with neutral feet. This second group also comprised 34 subjects with a mean age of 27.88 (10.49) years and a BMI of 22.28 (3.02) kg/m2. All these measurements were undertaken at the Podiatric Clinic of the University of Extremadura (Centro Universitario de Plasencia). The diagnosis of a ‘‘neutral foot’’ was made on the basis of the foot posture index (FPI) [17]. For these measurements, the subjects were asked to stand in their relaxed stance position with double limb support, their arms relaxed at their sides and looking straight ahead. Considering that the FPI has demonstrated good intra-observer reliability but only moderate inter-observer reliability [18], all the measurements were made by the same examiner. The six criteria used in the FPI were talar head palpation, supra and infra malleolar curvature, calcaneal frontal plane position, prominence in the region of the talonavicular joint, congruence of the medial longitudinal arch, and abduction/adduction of the forefoot on the rearfoot. Each criterion is scored on a scale ranging between 12 and +12, with the foot considered to be neutral when the score was between 2 and +2, pronated between +2 and +12, and supinated between 2 and 12 [17]. The selection criteria for the subjects in both groups were to be of legal adult age, no degenerative bone or joint disease, no foot surgery or trauma, and not reporting any area of pain in the lower limbs that might induce a compensatory abnormal gait. The baropodometry platform used in measuring plantar pressure was the Footscan USB Gait Clinical System1 (2 m 0.4 m 0.02 m, 16,384 sensors, 500 Hz, and 3 sensors per cm2). All the subjects were asked to walk barefoot on the platform at their normal walking pace and cadence. The variables studied were: contact surface area, pressure under each metatarsal head, pressure under the forefoot including the toes (sum of the pressures under each metatarsal head area and the zone of the toes), pressure under the metatarsal zone (sum of the pressures under each metatarsal head), pressure under the midfoot, and pressure under the heel. The subjects were asked to walk across the platform several times. The value recorded for each variable was the mean of the random measurements corresponding to six steps with the dominant foot. Statistical analyses were performed using the SPSS 17.0 software package. The Student’s t-test for independent samples was applied to determine whether the differences in the variables between the two groups were significant. The significance level was taken to be p < 0.05. 3. Results Table 1 shows the mean values and standard deviations in the plantar pressures records (kPa) for the different zones of the foot
and the support surface area in both groups. Pressures are greater for the pes cavus group under the metatarsal area as a whole and under each metatarsal head separately, with a significant difference in all these zones except under the 5th metatarsal. The differences in the rest of the zones are not significant, except for lower pressure under the toes. The reduction in the contact surface area in the pes cavus group is also significant. Table 2 lists the percentages of the load borne by each zone of the foot in both groups. 4. Discussion Knowledge of the baropodometry in neutral feet makes it possible to analyze the pressure distribution under pathological conditions. The present results have shown that most of the load in pes cavus individuals is borne by the forefoot (Table 2). The differences with neutral feet were only significant in the region of the forefoot (Table 1). No studies have been found in the literature providing evidence to explain these findings, but we hypothesize that, in the pes cavus subjects, the increased metatarsal verticality produces a greater transmission of the load to the forefoot [19], especially in the first metatarsal area. Besides, the reduction of the weight-bearing surface area (Table 1) does not lead to a redistribution of the pressure over all the zones of the foot as it was initially expected. Instead, it produces an overload only on the anterior zone. While some studies on subjects with neutral feet report that the zone of the forefoot subjected to the greatest load is the second metatarsal [11–13], others disagree [20–22]. Many factors need to be taken into account to judge whether these results do really reflect a lack of uniformity. There is a need to know whether the study was conducted with the individuals barefoot or shod and, in the latter case, the design and height of the shoe heel and the cushioning and hardness of the sole, since all these factors may have an influence upon the reported differences. Further factors are the use of different measuring systems and how the various parameters involved in the measurements are controlled [12]. This is why this study was designed with the same method and the same protocol for both groups. The results showed that, in both groups, the second and third metatarsal heads bore the greatest pressure. Doncker and Kowalski found that this is due to the anatomical structure of this zone, with the second and third metatarsal bones being wedged between the cuneiform joints, and thus have less freedom of movement. Consequently, they are also less able to dissipate the load they receive [23]. It was observed that, in pes cavus, all the metatarsal heads bear more load than in neutral feet, the difference being significant in all but the fifth metatarsal. This is why we consider that the most vulnerable area in cavus feet is the forefoot [6,22]. Burns and Table 1 Comparison of plantar pressure mean values (kPa) in the various areas of the foot and of the contact area (cm2 in normal feet and pes cavus. Significance level p < 0.05.
Pressure 1st toe Pressure other toes Pressure 1st metatarsal Pressure 2nd metatarsal Pressure 3rd metatarsal Pressure 4th metatarsal Pressure 5th metatarsal Pressure forefoot Pressure metatarsal Pressure midfoot Pressure hindfoot Contact area
Normal foot (n = 34)
Pes cavus (n = 34)
p
100.14 (3.46) 27.51 (2.41) 55.56 (3.53) 123.03 (4.86) 157.44 (3.06) 114.98 (3.22) 52.89 (2.66) 631.36 (9.61) 503.79 (9.32) 28.62 (1.48) 270.13 (6.15) 165.04 (20.68)
56.69 (3.05) 15.95 (1.53) 99.12 (4.25) 158.36 (6.08) 186.44 (6.72) 147.21 (7.26) 65.01 (4.26) 728.69 (24.14) 656.12 (22.39) 34.08 (2.48) 300.45 (8.07) 118.26 (30.31)
GAIPOS-4072; No. of Pages 4 Gait & Posture xxx (2013) xxx–xxx
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Comparison of plantar pressures and contact area between normal and cavus foot Lourdes M. Ferna´ndez-Seguı´n a,1,*, Juan Antonio Diaz Mancha a,1, Raquel Sa´nchez Rodrı´guez b,2, Elena Escamilla Martı´nez b,2, Beatriz Go´mez Martı´n b,2, Javier Ramos Ortega c,1 a
Physiotherapy Department, University of Seville, Spain Nursing Department, University of Extremadura, Spain c Podology Department, University of Seville, Spain b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 4 February 2013 Received in revised form 13 October 2013 Accepted 21 October 2013
Background: In pes cavus, the medial longitudinal arch elevation reduces the contact surface area and consequently increases the corresponding plantar pressure measurements. This poor distribution of loads may produce associated pathology and pain in this or other areas of the body. Normal reference values need to be established in order to determine which patterns are prone to pathology. Objectives: To compare the plantar pressures and weight-bearing surface in a population with pes cavus to a population with neutral feet. Method: The sample comprised 68 adults, 34 with pes cavus and 34 with neutral feet. The Footscan USB Gait Clinical System1 was used as a platform to measure the total contact area and plantar pressure under the forefoot, midfoot, hindfoot, each metatarsal head, and the overall metatarsal area. A statistical analysis of the data was performed using Student’s t-test for independent samples. Results: The pes cavus subjects showed a significant reduction in their weight-bearing area [neutral feet: 165.04 (20.68) cm2; pes cavus: 118.26 (30.31) cm2; p < 0.001] and significantly increased pressures under all zones of the forefoot except the fifth metatarsal [metatarsal pressure: in neutral feet 503,797 (9.32) kPa; in pes cavus 656.12 (22.39) kPa; p < 0.001]. Conclusions: Compared to neutral feet, pes cavus feet show a reduction in total contact surface and the load under the first toe. A significant increase is present in the load under the metatarsal areas, but the relative distribution of this load is similar in both groups. ß 2013 Elsevier B.V. All rights reserved.
Keywords: Cavus foot Normal foot Plantar pressure Contact surface Baropodometry
1. Introduction Foot pain is highly prevalent and may be associated with foot deformities, leg pain and lower back pain [1]. Estimates indicate that about 10–15% of the general population have cavus feet [2,3] and 60% of these have suffered pain, which is presumed to be related to excessive pressure, at some time in their lives [4,5]. The main feature of pes cavus, in so far as plantar pressure is concerned, is that the contact zone of the midfoot is reduced compared to neutral feet, resulting in increased pressure in this
* Corresponding author at: Facultad de Enfermerı´a, Fisioterapia y Podologı´a, Centro Docente de Fisioterapia y Podologı´a, c/Avicena s/n, 41009 Sevilla, Spain. Tel.: +34 954486505. E-mail address: [email protected] (L.M. Ferna´ndez-Seguı´n). 1 Facultad de Enfermerı´a, Fisioterapia y Podologı´a, Centro Docente de Fisioterapia y Podologı´a, c/Avicena s/n, 41009 Sevilla, Spain. 2 Centro Universitario, Avenida Virgen del Puerto, numero 2, 10600 Plasencia, Ca´ceres, Spain.
area. This increased pressure may lead to the occurrence of foot pathologies and pain. However, in order to determine whether or not this is a reasonable assumption, a comparison with the baropodometry of neutral feet is required, so as to observe whether or not there are large differences in the recorded pressure values. In reviewing the literature, a lack of agreement was found regarding plantar pressure distribution in neutral feet. Some suggest that the loads are evenly distributed between the forefoot and the hindfoot [6], others that the ratio is three parts on the forefoot and five parts on the hindfoot [7], and yet others describe a variety of comfortable standing positions with the heel bearing between one and three times as much load as the forefoot [8]. Recent studies with current baropodometric platforms agree that, in normal feet, the pressure is slightly higher on the heel than on the forefoot, although without reaching the margins described historically [9,10]. There is also general agreement that, in the forefoot, the second and third metatarsal heads are the ones subjected to the greatest loads [11–13].
0966-6362/$ – see front matter ß 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gaitpost.2013.10.018
Please cite this article in press as: Ferna´ndez-Seguı´n LM, et al. Comparison of plantar pressures and contact area between normal and cavus foot. Gait Posture (2013), http://dx.doi.org/10.1016/j.gaitpost.2013.10.018
G Model
GAIPOS-4072; No. of Pages 4 L.M. Ferna´ndez-Seguı´n et al. / Gait & Posture xxx (2013) xxx–xxx
2
In pes cavus, the zone under the greatest load is the forefoot [4,5,14,15]. However, the distribution of this load beneath the forefoot has not yet been investigated. Therefore, the aim of this study was to measure and compare the plantar pressure in two populations; one comprising subjects classified as pes cavus and the other involving individuals with a neutral foot posture, paying particular attention to the metatarsal zone. 2. Methods We conducted a descriptive study based on a cross-sectional series of cases divided into two groups. The first stage involved collecting baropodometric measurements in a group of subjects with pes cavus. This group was comprised of 34 subjects with a mean age of 24.21 (5.18) years, and a BMI of 22.10 (2.64) kg/m2. The diagnosis of pes cavus was defined radiologically as an internal Bartani Costa angle less than 125 [16]. These measurements were undertaken at the Clinical Podiatry Area of the University of Seville. The second stage of the study was devoted to performing the corresponding baropodometric measurements in subjects with neutral feet. This second group also comprised 34 subjects with a mean age of 27.88 (10.49) years and a BMI of 22.28 (3.02) kg/m2. All these measurements were undertaken at the Podiatric Clinic of the University of Extremadura (Centro Universitario de Plasencia). The diagnosis of a ‘‘neutral foot’’ was made on the basis of the foot posture index (FPI) [17]. For these measurements, the subjects were asked to stand in their relaxed stance position with double limb support, their arms relaxed at their sides and looking straight ahead. Considering that the FPI has demonstrated good intra-observer reliability but only moderate inter-observer reliability [18], all the measurements were made by the same examiner. The six criteria used in the FPI were talar head palpation, supra and infra malleolar curvature, calcaneal frontal plane position, prominence in the region of the talonavicular joint, congruence of the medial longitudinal arch, and abduction/adduction of the forefoot on the rearfoot. Each criterion is scored on a scale ranging between 12 and +12, with the foot considered to be neutral when the score was between 2 and +2, pronated between +2 and +12, and supinated between 2 and 12 [17]. The selection criteria for the subjects in both groups were to be of legal adult age, no degenerative bone or joint disease, no foot surgery or trauma, and not reporting any area of pain in the lower limbs that might induce a compensatory abnormal gait. The baropodometry platform used in measuring plantar pressure was the Footscan USB Gait Clinical System1 (2 m 0.4 m 0.02 m, 16,384 sensors, 500 Hz, and 3 sensors per cm2). All the subjects were asked to walk barefoot on the platform at their normal walking pace and cadence. The variables studied were: contact surface area, pressure under each metatarsal head, pressure under the forefoot including the toes (sum of the pressures under each metatarsal head area and the zone of the toes), pressure under the metatarsal zone (sum of the pressures under each metatarsal head), pressure under the midfoot, and pressure under the heel. The subjects were asked to walk across the platform several times. The value recorded for each variable was the mean of the random measurements corresponding to six steps with the dominant foot. Statistical analyses were performed using the SPSS 17.0 software package. The Student’s t-test for independent samples was applied to determine whether the differences in the variables between the two groups were significant. The significance level was taken to be p < 0.05. 3. Results Table 1 shows the mean values and standard deviations in the plantar pressures records (kPa) for the different zones of the foot
and the support surface area in both groups. Pressures are greater for the pes cavus group under the metatarsal area as a whole and under each metatarsal head separately, with a significant difference in all these zones except under the 5th metatarsal. The differences in the rest of the zones are not significant, except for lower pressure under the toes. The reduction in the contact surface area in the pes cavus group is also significant. Table 2 lists the percentages of the load borne by each zone of the foot in both groups. 4. Discussion Knowledge of the baropodometry in neutral feet makes it possible to analyze the pressure distribution under pathological conditions. The present results have shown that most of the load in pes cavus individuals is borne by the forefoot (Table 2). The differences with neutral feet were only significant in the region of the forefoot (Table 1). No studies have been found in the literature providing evidence to explain these findings, but we hypothesize that, in the pes cavus subjects, the increased metatarsal verticality produces a greater transmission of the load to the forefoot [19], especially in the first metatarsal area. Besides, the reduction of the weight-bearing surface area (Table 1) does not lead to a redistribution of the pressure over all the zones of the foot as it was initially expected. Instead, it produces an overload only on the anterior zone. While some studies on subjects with neutral feet report that the zone of the forefoot subjected to the greatest load is the second metatarsal [11–13], others disagree [20–22]. Many factors need to be taken into account to judge whether these results do really reflect a lack of uniformity. There is a need to know whether the study was conducted with the individuals barefoot or shod and, in the latter case, the design and height of the shoe heel and the cushioning and hardness of the sole, since all these factors may have an influence upon the reported differences. Further factors are the use of different measuring systems and how the various parameters involved in the measurements are controlled [12]. This is why this study was designed with the same method and the same protocol for both groups. The results showed that, in both groups, the second and third metatarsal heads bore the greatest pressure. Doncker and Kowalski found that this is due to the anatomical structure of this zone, with the second and third metatarsal bones being wedged between the cuneiform joints, and thus have less freedom of movement. Consequently, they are also less able to dissipate the load they receive [23]. It was observed that, in pes cavus, all the metatarsal heads bear more load than in neutral feet, the difference being significant in all but the fifth metatarsal. This is why we consider that the most vulnerable area in cavus feet is the forefoot [6,22]. Burns and Table 1 Comparison of plantar pressure mean values (kPa) in the various areas of the foot and of the contact area (cm2 in normal feet and pes cavus. Significance level p < 0.05.
Pressure 1st toe Pressure other toes Pressure 1st metatarsal Pressure 2nd metatarsal Pressure 3rd metatarsal Pressure 4th metatarsal Pressure 5th metatarsal Pressure forefoot Pressure metatarsal Pressure midfoot Pressure hindfoot Contact area
Normal foot (n = 34)
Pes cavus (n = 34)
p
100.14 (3.46) 27.51 (2.41) 55.56 (3.53) 123.03 (4.86) 157.44 (3.06) 114.98 (3.22) 52.89 (2.66) 631.36 (9.61) 503.79 (9.32) 28.62 (1.48) 270.13 (6.15) 165.04 (20.68)
56.69 (3.05) 15.95 (1.53) 99.12 (4.25) 158.36 (6.08) 186.44 (6.72) 147.21 (7.26) 65.01 (4.26) 728.69 (24.14) 656.12 (22.39) 34.08 (2.48) 300.45 (8.07) 118.26 (30.31)
