www.elsevier.com/locate/diabres

Diabetes Research and Clinical Practice 77 (2007) 203–209

Daily-life activities and in-shoe forefoot plantar pressure

in patients with diabetes

Nick A. Guldemond a,*, Pieter Leffers b, Antal P. Sanders c, Nicolaas C. Schaper d,Fred Nieman e, Geert H.I.M. Walenkamp a

a Department Orthopaedic Surgery, University Hospital Maastricht, P.O. Box 5800, 6202 AZ Maastricht, The Netherlandsb Department of Epidemiology, Fac. Medicine, Maastricht University, The Netherlands

c Department Rehabilitation Medicine, University Hospital Maastricht, The Netherlandsd Department Internal Medicine, University Hospital Maastricht, The Netherlands

e Department Clinical Epidemiology and Medical Technology Assessment, University Hospital Maastricht, The Netherlands

Received 21 April 2006; accepted 17 November 2006

Available online 21 December 2006

Abstract

Objective: To assess differences regarding in-shoe forefoot plantar pressure (PP) in patients with diabetes during various daily-life

activities.

Research design and methods: In-shoe PP was measured in 93 patients during: level walking, ramp and stair walking, turning in

different settings and while performing the Up & Go test. Separate PPs were determined for the big toe and metatarsal (mt) regions

one to five.

Results: Across all activities, similar PPs were measured in the big toe and mt-1 to mt-3 region. Lower PPs were measured in mt-4

and mt-5 region. PPs during level walking were mostly higher when compared to the other activities ( p � .030). Turning while level

walking resulted in higher PPs than turning while performing the other activities ( p � .033). Higher PPs were measured for both

ramp and stair ascending when compared to descending ( p � .001). In the big toe region, stair descending resulted in higher PPs

than ascending ( p � .001). Across all activities, patients with neuropathy had lower PPs (overall mean 28 kPa) than patients without

neuropathy.

Conclusions: Level walking resulted in the highest forefoot PPs during daily-life activities. Patients with neuropathy had lower PPs

than patients without neuropathy.

# 2006 Elsevier Ireland Ltd. All rights reserved.

Keywords: Daily activities; Diabetic foot; Plantar pressure; Screening

1. Introduction

Since the introduction of electronic equipment for

plantar pressure measurement, the majority of research

* Corresponding author. Tel.: +31 43 3875031;

fax: +31 43 3874893.

E-mail addresses: ngu@orthop.unimaas.nl, ngu@sort.azm.nl

(N.A. Guldemond).

0168-8227/$ – see front matter # 2006 Elsevier Ireland Ltd. All rights re

doi:10.1016/j.diabres.2006.11.006

regarding the biomechanics of the diabetic foot has been

performed with pressure sensitive platforms and has

been focused mainly on plantar bare foot loading. The

application of pressure sensitive platforms is limited to

laboratory settings and most platforms allow only one

step per run for recording. At the beginning of the

1990s, commercial equipment for in-shoe pressure

measurement became available and is now commonly

used in research as well as in clinical settings. In-shoe

served.

N.A. Guldemond et al. / Diabetes Research and Clinical Practice 77 (2007) 203–209204

plantar pressure measurement provides the opportunity

for collecting multiple steps per run.

In-shoe plantar pressure is usually measured during

walking straight on level ground. In previous reports, it

was questioned whether such plantar pressures were

representative for plantar pressures during activities of

daily living [1–3]. Until now, only a few studies have

evaluated in-shoe plantar pressures under more real life

circumstances [2–6]. Only one of these studies was

performed in patients with diabetes and peripheral

neuropathy. Several results of these small sample size

studies were conflicting, e.g. one found that plantar

pressures were lower during turning than straight level

walking [2], while others found the opposite [3,5]. The

primary objective of the present study was to determine

differences between various activities regarding fore-

foot in-shoe plantar pressures in diabetic patients. The

secondary objective was to evaluate whether there were

differences for these activities as far patients with and

without peripheral neuropathy were concerned. We

compared straight level walking with turning, with the

Up & Go test and with ramp and stair walking.

2. Materials and methods

2.1. Patients

Diabetic patients were selected from the medical outpa-

tient clinic of the University Hospital Maastricht. Inclusion

criteria were diabetes mellitus type 1 (longer than 10 years

after date of diagnosis) or type 2 (at least 1 year after date of

diagnosis); age between 30 and 75 years and able to perform

daily-life activities without supporting devices. Exclusion

criteria were a history of rheumatoid arthritis, foot trauma

Table 1

Patient characteristics

n

Gender (female/male)

Type of DM (1/2)

Female Male

Mean S.D. Min–max Mean S.D. Mi

Age (years) 56.3 9.06 34–69 50.9 9.52 3

Duration diabetes

(years)

13.8 10.16 3–39 11.6 7.70

HBa1c (%) 8.31 1.51 5.9–10.7 8.15 1.08 5.

Body mass index

(kg/m2)

28.9 5.17 19.8–39.6 28.2 4.83 20.

VPT 12.3 4.06 5.2–20.5 13.9 5.18 5.

Walking speed (m/s) 1.04 0.11 0.91–1.28 1.08 0.16 0.7

PNP+, peripheral polyneuropathy; PNP�, no peripheral polyneuropathy; D

hemoglobin A1c.

surgery of the foot and/or severe deformity. The latter included

pes cavus, i.e. an excessively elevated foot arch, hallux valgus

more than 158 and severe toe deformity. The degree of hallux

valgus was measured according to the guidelines of the

American Academy of Orthopaedic Surgeons [7]. The pre-

sence of claw toe, mallet toe, curly toe or hammer toe

deformity, was scored according to the definitions of Myerson

and Shereff [8]. The degree of toe deformity was arbitrarily

defined as less (minor), the same (significant) or more (severe)

than the definitions described by Myerson and Shereff,

whereas ‘normal toe’ was recorded if there was no malalign-

ment present. In addition, the medial arch height was sub-

jectively classified as: no arch; lowered arch; normal arch;

elevated arch and excessively elevated arch. Before the start of

the study, patients were informed about all study procedures

and their possible risks. The Research Ethical Committee of

the University Hospital Maastricht approved the study.

Ninety-three eligible patients were screened for peripheral

neuropathy through determination of the vibration perception

thresholds (VPT) at the apex of the hallux with a biothesi-

ometer (Biomedical, Newbury OH) [9–11]. AVPT higher than

25 V was used as the diagnostic criterion for peripheral

neuropathy: �25 V = PNP�, >25 V = PNP+. Table 1 con-

tains descriptive data with respect to gender, age, body mass

index (BMI), duration of diabetes, VPT, HBa1c and walking

speed.

2.2. Procedures

The following timed activities were evaluated: level walk-

ing, the Up & Go test, ascending and descending a ramp and a

flight of stairs (Table 2). Level walking: patients walked two

lengths of 10 m (turn excluded) indoors on a concrete floor in

one single run. Ascending and descending a ramp: patients

ascended and descended a 15% grade ramp of 4 m and turned

on a platform of 62 cm length by 81 cm width. This was a

PNP� PNP+

49 44

30/19 29/15

18/31 9/35

Female Male

n–max Mean S.D. Min–max Mean S.D. Min–max

2–70 64.9 8.79 49–75 58.8 10.42 34–72

1–32 18.1 11.35 2–40 16.3 11.39 3–45

1–9.7 8.25 1.29 6.3–11.8 8.16 1.25 5.7–12.0

1–38.0 31.2 7.37 20.0–45.7 29.6 6.44 19.8–45.3

7–23.3 41.9 9.79 24.8–50.0 41.3 11.84 14.5–50.0

1–1.50 0.85 0.13 0.67–1.09 1.05 0.20 0.60–1.38

M, diabetes mellitus; VPT, vibration perception threshold; HbA1c,

N.A. Guldemond et al. / Diabetes Research and Clinical Practice 77 (2007) 203–209 205

Fig. 1. Peak pressures during daily-life activities. L, level walking; U,

Up & Go test; RA, ramp ascending; RD, ramp descending; SA, stair

ascending; SD, stair descending; LT, turning while level walking; UT,

turning while performing Up & Go test; RT, turning while ramp

walking; ST, turning while stair walking; mt, metatarsal; kPa, kilo-

Pascal.

Table 2

Information about activities, number of steps used for analysis and groups of comparison for statistical testing

Activity Trials per patient Distance per trial Turns clockwise Turns counter-clockwise Average number of steps

per patient used for analysis

Straight on performance Turns

Level walking 4 2 m � 10 m 2� 2� 40 8

Up & Go test 2 2 m � 3 m 1� 1� 8 4

Ramp ascending 2 2 m � 4 m 1� 1� 6 4

Ramp descending 2 2 m � 4 m 1� 1� 6

Stair ascending 2 2 m � 3 m 1� 1� 14 4

Stair descending 2 2 m � 3 m 1� 1� 14

Groups of comparison

Level walking vs. other activities L vs. U L vs. RA L vs. SA L vs. LT

Turning while level walking vs. turning during other activities LT vs. UT LT vs. RT LT vs. ST UT vs. RT UT vs. ST RT vs. ST

Ascending vs. descending RA vs. RD SA vs. SD

L, level walking; U, Up & Go test; RA, ramp ascending; RD, ramp descending; SA, stair ascending; SD, stair descending; LT, turning while level

walking; UT, turning while performing Up & Go test; RT, turning while ramp walking; ST, turning while stair walking.

typical a situation in which a subject would turn at a low speed

with a small perimeter. Upstairs and downstairs walking:

patients were asked to ascend and descend 10 stairs in their

usual manner (step height 18 cm; board depth 27 cm; 33 grade

inclination). Unilateral use of a handrail was obligatory and

they turned on the landing of the stairwell. For the aforemen-

tioned activities patients were instructed to walk and turn at a

safe and comfortable pace. Timed Up & Go test: patients were

asked to rise from a standard chair (seat height 45 cm), walk to

and turn around a pylon, which was placed 3 m from the chair,

and return to a sitting position in the chair [12]. Patients were

instructed to ‘‘perform the activity as quickly as you can

without overexerting yourself’’. This was a typical test situa-

tion in which a subject would accelerate and decelerate at a

relatively high speed in combination with a turn around a

small perimeter.

During all activities plantar peak pressures were measured

with a frequency of 50 Hz per sensor with the Pedar Insole-

system1 (Novel, Munich Germany). The Pedar insoles con-

sisted of a matrix of 99 sensors with an average individual

sensor effective area of approximately 1.5 cm2 and were

placed in both shoes between the socks and shoes. For patient

measurement, the insoles were calibrated to absolute values

using the Trublu1 calibration device (Novel, Munich Ger-

many). A ‘relative or zero calibration’ was performed imme-

diately before each trial by unloading each insole. The Pedar

processing unit was worn in a waist pocket. Plantar pressure

data were recorded with a computer through a 15 m umbilical

cable which was guided during the measurements. All patients

performed the activities in a randomized order in standard

socks and shoes of various widths and neutral fore-/rear foot

height (males: Van Lier: outer sole hardness, i.e. shore type A:

68, No 814 Loon op Zand, Netherlands and females: Durea

Greenway: outer sole shore type A: 63, No 6548 Drunen

Netherlands). These shoes are oxford style shoes with a

relatively stiff innersole material (Shore A higher than 60

[13]) They were used in order to minimize the influence of

‘cushioning’ on plantar pressure loading and without any

specific adaptation they are not necessarily appropriate for

diabetic feet. This type of shoe is close to what is commonly

worn in the Dutch elderly population. The shoe fitting was

checked according the guidelines described by Shor [14].

Time was measured to the nearest 1/10 of a second using a

stopwatch with interval memory storage.

2.3. Data processing

Pedar Expert1 software (Novel, Munich Germany) was

used to select steps from the raw data files. The assignment of

steps to walking or turning was made by using the recording

time in the data files and the stopwatch intervals. The evalua-

tion was focused on six forefoot regions: big toe and meta-

tarsal one (mt-1) to five (mt-5). The mask for these ‘regions of

N.A. Guldemond et al. / Diabetes Research and Clinical Practice 77 (2007) 203–209206T

able

3

Pea

kp

ress

ure

sd

uri

ng

dai

ly-l

ife

acti

vit

ies

(kP

a)

Big

toe

Met

atar

sal

1M

etat

arsa

l2

Met

atar

sal

3M

etat

arsa

l4

Met

atar

sal

5

MS

.E.

Min

–m

axM

S.E

.M

in–

max

MS

.E.

Min

-Max

MS

EM

in–

max

MS

.E.

Min

–m

axM

S.E

.M

in–

max

L2

49

8.9

88

–48

12

48

8.7

61

–61

52

75

9.8

12

7–5

99

26

41

0.4

11

0–6

74

18

77

.65

3–

39

31

34

4.2

47

–2

39

U2

08

7.5

73

–44

52

13

7.4

48

–49

52

23

7.7

71

–45

62

14

8.1

64

–51

11

57

6.1

60

–33

71

18

3.7

50

–2

11

RA

24

19

.68

6–

53

22

51

9.8

68

–60

22

68

10

.09

8–

57

62

53

10

.47

9–

65

21

79

7.4

68

–42

81

30

4.4

32

–2

69

RD

21

78

.56

0–

48

22

02

9.1

21

–53

92

09

7.9

81

–42

31

96

7.8

76

–41

81

47

5.9

56

–33

41

19

5.0

42

–2

52

SA

15

61

0.4

8–

513

22

78

.08

1–

46

32

50

9.1

94

–51

22

34

9.6

76

–57

91

74

8.7

34

–42

21

44

5.5

42

–2

95

SD

18

79

.95

7–

50

02

26

8.2

43

–52

42

25

7.5

58

–41

72

15

7.9

70

–42

61

53

6.2

62

–33

71

26

4.9

47

–2

85

LT

22

57

.99

2–

45

92

29

8.4

66

–53

62

44

8.5

93

–45

42

35

8.9

92

–49

21

74

6.9

54

–34

31

34

4.7

48

–2

75

UT

21

68

.37

4–

41

82

17

8.6

45

–55

02

27

7.9

60

–43

52

13

8.1

77

–51

31

61

6.4

53

–34

51

27

4.4

45

–2

98

RT

16

86

.24

1–

33

81

65

6.9

29

–51

81

61

5.9

50

–34

81

59

6.8

59

–34

81

27

4.6

54

–29

31

08

4.4

28

–2

28

ST

16

86

.85

9–

34

31

78

7.0

39

–48

31

71

5.7

70

–36

31

64

6.2

70

–35

31

33

4.7

59

–27

21

13

4.2

27

–2

43

L,l

evel

wal

kin

g;U

,Up

&G

ote

st;R

A,r

amp

asce

nd

ing

;RD

,ram

pd

esce

nd

ing

;SA

,sta

iras

cen

din

g;S

D,s

tair

des

cen

din

g;L

T,t

urn

ing

wh

ile

level

wal

kin

g;U

T,t

urn

ing

wh

ile

per

form

ing

Up

&G

ote

st;

RT

,tu

rnin

gw

hil

era

mp

wal

kin

g;

ST

,tu

rnin

gw

hil

est

air

wal

kin

g;

M,

mea

n;

S.E

.,st

and

ard

erro

r;M

in,

min

imu

m;

Max

,m

axim

um

.

interest’ was designed using Novel ‘create any mask1’ soft-

ware and verified by individual anterior-posterior radiographs

of the foot [15]. Peak pressure was estimated by calculating

the mean over the total number of steps per activity collected

from various trials Table 2. The mean speed during level

walking was based on the time required to traverse 10 m; per

patient an average of eight measurements was used: 2 � 10 m

lengths (turn excluded) per trial with a total of four trials.

2.4. Statistical analysis

At first plantar pressure data of all activities were inves-

tigated for normal distribution by the Kolmogorov–Smirnov

test. Repeated measures ANOVA design was used for ana-

lysis with one between- and two within-factors: The

between-factor was defined as ‘neuropathy’ with two cate-

gories (patients with and without neuropathy). The within-

factors were defined as ‘activity’ with 10 categories (all

aforementioned activities) and ‘side’ with 2 categories (left

and right foot). For each factor, overall F-ratio tests were

corrected for sphericity violations in the variance–covar-

iance matrix by using the Greenhouse–Geisser degrees of

freedom making the tests more conservative. Mauchly’s test

of sphericity was used to decide whether this correction was

necessary. Specific category differences were investigated

using reversed Helmert contrasts. The following compari-

sons were made: level walking versus the Up & Go test, ramp

ascending, stair ascending and turning while level walking.

Also, we wanted to know whether various styles of turning

would result in different forefoot pressures. Finally, we were

interested in the differences in peak pressure between

ascending and descending for both ramp and stair walking

(Table 2). All comparisons in the analysis were performed

with the peak pressure calculated for the six forefoot regions.

Statistical analysis was carried out with SPSS 12.011 soft-

ware (SPSS Inc.). An alpha level of 0.05 was chosen to judge

statistical significance.

3. Results

Because the conceptual and statistical problems

associated with analysing both feet of one subject,

repeated measures ANOVA, with side as within factor,

was used for statistical testing. In the overall F-ratio test

this analysis showed no statistically significant differ-

ence in peak pressure between left and right foot.

Therefore, the values for each region over both left and

right feet were averaged. The peak pressures for all

activities per forefoot region are presented in Fig. 1 and

Table 3.

For most activities the mt-2 region had the highest

peak pressure. However, for all activities peak pressures

measured in the mt-1 to mt-3 and the big toe regions

were fairly similar. The only deviation from this pattern

is that the peak pressure for the big toe was lower during

N.A. Guldemond et al. / Diabetes Research and Clinical Practice 77 (2007) 203–209 207

stair walking. Across all activities, lower peak pressures

were measured in mt-4 and mt-5 region compared to the

other regions.

In most forefoot regions, peak pressure during level

walking was higher compared to the other activities

( p � .030). Only for the mt-1 and the mt-5 region,

differences in peak pressure between level walking and

turning while level walking, and between level walking

and ramp ascending were not statistically significant.

For all forefoot plantar regions, turning while level

walking resulted in higher peak pressures, than turning

while performing the Up & Go test, ramp walking and

stair walking ( p � .033). Also, turning while perform-

ing the Up & Go test resulted in higher peak pressure,

compared to turning while ramp and stair walking

( p � .001).

A higher peak pressure was measured for both ramp

and stair ascending in most forefoot regions when

compared to ramp and stair descending ( p � .001). For

the mt-1 regions the difference was not statistically

significant. In the big toe region, stair descending

resulted in a higher peak pressure than ascending

( p � .001).

Across all activities, patients with neuropathy had

lower peak pressures than patients without neuropathy.

Repeated measures ANOVA showed that the overall

effect was 28 kPa (difference of sample means) with a

standard error of the difference of 19.4 (F (1,91) 6.78,

p = .011). The ranking of the activities from the highest

to lowest peak pressure, as shown in Fig. 1, was the

same for patients with and without neuropathy.

4. Discussion

We studied in-shoe forefoot plantar pressure

during simulated daily-life activities in diabetic

patients. The highest peak pressures for all activities

were measured in the mt-1 to mt-3 regions. In these

regions, level walking and ramp ascending resulted in

the highest peak pressure. Peak pressures were lower

in patients with neuropathy than in patients without

neuropathy.

Our finding that level walking and ascending a ramp

resulted in the highest forefoot peak pressure compared

to the other activities contradicts previous studies that

report that activities like turning, ramp and stair walking

result in higher peak pressure than straight level

walking [3,5] and are similar to those of Maluf et al. [2].

Rozema et al. found that the plantar pressures during

rising from and sitting down on a chair were much lower

than during level walking [3]. These measurements

were performed from and to a ‘static standing position’.

We expected that a more real-life approach of the

transfer from walking to sitting and vice versa would

lead to higher peak pressures. Although patients in our

study were encouraged to perform the Up & Go test as

quickly as possible, this test did not lead to higher

plantar pressures when compared to level walking. We

averaged peak pressures during sitting down and rising

from a chair, consequently no comparisons between

these activities were made.

As reported in other studies, stair walking resulted in

lower plantar pressures than did level walking [2,3]. The

peak pressure in the big toe region was surprisingly low

compared to level walking and ramp ascending.

Contrary to other forefoot regions the big toe was

more loaded during stair descending than stair

ascending.

Our study shows that turning resulted in lower peak

pressures, which supports the results of Maluf et al. [2].

Rozema et al. reported that plantar pressure was higher

during turning when compared to straight level walking

[3]. In this study turning was performed while ‘‘walking

between two concentric circles’’ at a constant speed of

1.6 m/s, which is a much faster then the straight level

walking speed of our patients. Our impression is that

patients mostly slow down before turning and then turn

at a lower speed. Such anticipative turning related gait

was also found in a recent study with elderly subjects

[16]. Additionally, peak pressures further decreased

during turning while ramp and stair walking where a

slower speed was required than during level walking.

Even when we tried to provoke high plantar pressures

with swift ‘pivot’ turning as in the Up & Go test, peak

pressures were lower than level walking. Unfortunately

we have no adequate data on walking speed during this

test. We made no differentiation between in and outside

feet for the analysis of turning activities. Consequently,

small differences for in and outside foot peak pressure,

as have been found in previous studies [2,3], were

possibly averaged out. Also, from a real-life perspec-

tive, it is not to be expected that daily cumulative plantar

stress becomes asymmetrical through turning, since it is

unlikely that people will consistently turn in one

direction.

Patients with neuropathy showed slightly lower peak

pressures (about 10%) during all activities than patients

without neuropathy. The relatively large standard errors

indicate that the spread of peak pressures in both groups

is very large.

It is commonly thought that patients with neuropathy

experience higher plantar pressures during daily-life

activities than diabetic patients without neuropathy

[17,18]. This idea is based on results from bare foot

N.A. Guldemond et al. / Diabetes Research and Clinical Practice 77 (2007) 203–209208

plantar pressure studies, which showed that patients

with neuropathy have higher plantar pressure than

patients without neuropathy or healthy controls [19–

26]. Our study shows that in-shoe plantar pressure

during daily life activities is lower in neuropathic

patients. The present analysis was not focused on the

causal mechanism for the explanation of the difference

in plantar pressure between patients with and without

neuropathy. The slower walking speed of patients with

neuropathy probably explains at least part of the

difference in peak pressure, while also adaptive gait

style may play a role. We studied diabetic patients

without severe deformities, limited joint mobility and

gait abnormalities. Some of the results might well be

different in patients with these complications of

diabetes. Further studies in such patient groups are

warranted.

The present study is an added piece in the puzzle of

how foot ulcers develop. In general, daily plantar foot

loading has four determinants: (1) footwear, (2)

performed activity, (3) number of loading cycles and

(4) the temporal pattern of activities.

It is obvious that activity patterns between indivi-

duals vary a lot. Armstrong et al. [27] showed that intra-

individual activity fluctuates; periods of inactivity are

punctuated by relatively sudden pulses of activity over a

short time frame. From the study of Maluf et al. [2] and

our own study it appears that straight level walking for a

longer period of time seems to be less favourable

activity than ‘moving around the house’. Because of the

large variation in used personal footwear and plantar

loading characteristics, inter-individual differences

must be considered in estimating risk for ulceration

in an ‘every day’ perspective.

5. Conclusions

Level walking and ascending a ramp resulted in the

highest forefoot peak pressure compared to other

simulated daily-life activities such as ramp descending,

stair walking, rising from and sitting down on a chair.

Compared to descending, ascending a ramp or stairs

resulted in higher peak pressures. An exception is the

big toe region which had a lower pressure during stair

ascending. Across all activities and plantar regions,

peak pressures were lower for patients with neuropathy

than patients without neuropathy.

Acknowledgement

This study was supported by the Dutch Diabetes

Research Foundation.

References

[1] P. Cavanagh, F. Hewitt, J. Perry, In shoe plantar pressure

measurement: a review, Foot 2 (1992) 185–194.

[2] K.S. Maluf, R.E. Morley Jr., E.J. Richter, J.W. Klaesner, M.J.

Mueller, Foot pressures during level walking are strongly asso-

ciated with pressures during other ambulatory activities in

subjects with diabetic neuropathy, Arch. Phys. Med. Rehabil.

85 (2) (2004) 253–260.

[3] A. Rozema, J.S. Ulbrecht, S.E. Pammer, P.R. Cavanagh, In-shoe

plantar pressures during activities of daily living: implications

for therapeutic footwear design, Foot Ankle Int. 17 (6) (1996)

352–359.

[4] J. Grampp, J. Willson, T. Kernozek, The plantar loading varia-

tions to uphill and downhill gradients during treadmill walking.,

Foot Ankle Int. 21 (3) (2000) 227–231.

[5] S. Lundeen, K. Lundquist, M.W. Cornwall, T.G. McPoil, Plantar

pressures during level walking compared with other ambulatory

activities, Foot Ankle Int. 15 (6) (1994) 324–328.

[6] A. Szczepaniak, B. Dredrup, A. Guttmann, H.H. Wetz, Plantar

loading pattern in step-to level and stair climbing, in: Biome-

chanics of The Lower Limb in Health, Disease and Rehabilita-

tion, University of Salford, Salford (Greater Manchester),

2003 .

[7] AAOS, Joint Motion: Method of Measuring and Recording.

Churchill-Livingstone 1965. Chicago. ISBN: 0892030909.

[8] M.S. Myerson, M.J. Shereff, The pathological anatomy of claw

and hammer toes, J. Bone Joint. Surg. Am. 71 (1) (1989) 45–49.

[9] R.W. van Deursen, M.M. Sanchez, J.A. Derr, M.B. Becker, J.S.

Ulbrecht, P.R. Cavanagh, Vibration perception threshold testing

in patients with diabetic neuropathy: ceiling effects and relia-

bility, Diabet. Med. 18 (6) (2001) 469–475.

[10] S. Bloom, S. Till, P. Sonksen, S. Smith, Use of a biothesiometer

to measure individual vibration thresholds and their variation in

519 non-diabetic subjects, Br. Med. J. (Clin. Res. Ed.) 288

(6433) (1984) 1793–1795.

[11] P.J. Dyck, P.C. O’Brien, Quantitative sensation testing in epi-

demiological and therapeutic studies of peripheral neuropathy,

Muscle Nerve 22 (6) (1999) 659–662.

[12] D. Podsiadlo, S. Richardson, The timed ‘‘Up & Go’’: a test of

basic functional mobility for frail elderly persons, J. Am. Geriatr.

Soc. 39 (2) (1991) 142–148.

[13] G. Charanya, K.M. Patil, V.B. Narayanamurthy, R. Parivalavan,

K. Visvanathan, Effect of foot sole hardness, thickness and

footwear on foot pressure distribution parameters in diabetic

neuropathy, Proc. Inst. Mech. Eng. [H] 218 (6) (2004) 431–443.

[14] R. Shor, Shoe fitting for the at-risk diabetic patient: a proper

fitting shoe leads to better treatment results, Podiat. Manage

(October) (2003).

[15] R.E. Weijers, G.H. Walenkamp, H. van Mameren, A.G. Kessels,

The relationship of the position of the metatarsal heads and peak

plantar pressure, Foot Ankle Int. 24 (4) (2003) 349–353.

[16] P. Meinhart-Shibata, M. Kramer, J.A. Ashton-Miller, C. Persad,

Kinematic analyses of the 180 degrees standing turn: effects of

age on strategies adopted by healthy young and older women,

Gait Posture 22 (2) (2005) 119–125.

[17] P.R. Cavanagh, G.G. Simoneau, J.S. Ulbrecht, Ulceration,

unsteadiness, and uncertainty: the biomechanical consequences

of diabetes mellitus, J. Biomech. 26 (Suppl. 1) (1993) 23–40.

[18] A. Veves, H.J. Murray, M.J. Young, A.J. Boulton, The risk of foot

ulceration in diabetic patients with high foot pressure: a pro-

spective study, Diabetologia 35 (7) (1992) 660–663.

N.A. Guldemond et al. / Diabetes Research and Clinical Practice 77 (2007) 203–209 209

[19] R.M. Stess, S.R. Jensen, R. Mirmiran, The role of dynamic

plantar pressures in diabetic foot ulcers, Diab. Care 20 (5) (1997)

855–858.

[20] J.E. Shaw, C.H. van Schie, A.L. Carrington, C.A. Abbott, A.J.

Boulton, An analysis of dynamic forces transmitted through the

foot in diabetic neuropathy, Diab. Care 21 (11) (1998) 1955–

1999.

[21] I.A. Stokes, I.B. Faris, W.C. Hutton, The neuropathic ulcer and

loads on the foot in diabetic patients, Acta Orthop. Scand. 46 (5)

(1975) 839–847.

[22] E.C. Katoulis, A.J. Boulton, S.A. Raptis, The role of diabetic

neuropathy and high plantar pressures in the pathogenesis of foot

ulceration, Horm. Metab. Res. 28 (4) (1996) 159–164.

[23] R.G. Frykberg, L.A. Lavery, H. Pham, C. Harvey, L. Harkless, A.

Veves, Role of neuropathy and high foot pressures in diabetic

foot ulceration, Diab. Care 21 (10) (1998) 1714–1719.

[24] G.C. Ctercteko, M. Dhanendran, W.C. Hutton, L.P. Le

Quesne, Vertical forces acting on the feet of diabetic patients

with neuropathic ulceration, Br. J. Surg. 68 (9) (1981) 608–

614.

[25] L. Uccioli, A. Caselli, C. Giacomozzi, V. Macellari, L. Giurato,

L. Lardieri, et al., Pattern of abnormal tangential forces in the

diabetic neuropathic foot, Clin. Biomech. (Bristol, Avon) 16 (5)

(2001) 446–454.

[26] Z. Pataky, J.-P. Assal, P. Conne, H. Vuagnat, A. Golay, Plantar

pressure distribution in type 2 diabetic patients without periph-

eral neuropathy and peripheral vascular disease, Diabet. Med. 22

(6) (2005) 762–767.

[27] D.G. Armstrong, L.A. Lavery, K. Holtz-Neiderer, M.J. Mohler,

C.S. Wendel, B.P. Nixon, et al., Variability in activity may

precede diabetic foot ulceration, Diab. Care 27 (8) (2004)

1980–1984.