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July2005 Vol.42 Issue:      2 Table of Contents
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Effectiveness of Weightbearing Exercises on Forefoot Planter Pressure in Diabetic Peripheral Neuropathy

G. Mousa, Sherin Fathi2

Departments of Neuromuscular Disorders and its Surgery1,

Faculty of Physical Therapy, Neurology2, Faculty of Medicine, Cairo University



ABSTRACT

The purpose of this study was to determine the effect of weight bearing exercises of the lower extremities on peak forefoot planter pressure in patients with diabetic peripheral neuropathy. Thirty patients(mean age= 44.76±6.1) were randomized into two equal groups. The control group received traditional physical therapy program while the study group received additional weight-bearing exercises for 12 weeks as five times per week. All patients were evaluated with Mat foot scan pressure system prior to treatment program and at the completion of the treatment period. The peak forefoot planter pressure improved significantly in both groups after the treatment program. However, the improvement in the study group was statistically significant compared to the control group and this reduction in peak forefoot planter pressure was associated with improvement in functional performance.

(Egypt J. Neurol. Psychiat. Neurosurg., 2005, 42(2): 351-358).





INTRODUCTION

 

Sensorimotor peripheral neuropathy (PN) is one of the frequent complication of diabetes.1 The sensory impairment identified as a significant worse proprioceptive acuity in ankle inversion and eversion compared to healthy people.2 Impaired ankle joint proprioception has been tentatively identified as closely associated with increased standing sway3. So, these patients are not likely able to perceive ground irregularities and subtle shifts in their centers of mass and are, therefore predisposed to fall4. In addition, motor impairment of the ankle is associated with postural instability and markedly increases risk for falls5.

Neuropathy prevents people from detecting pain, therefore, they are unable to adjust gait to avoid walking on an area where the pressure is causing trauma and necrosis6. There is also atrophy of the intrinsic muscles of the foot which causes instability of the metatarsophalangeal joints and anterior migration and displacement of the fat pad that is normally located directly under the metatarsal heads. Anterior displacement of the fat pad causes abnormally high pressure underneath the forefoot and become more vulnerable to injury from accumulated trauma during walking7.

Limited ankle dorsiflexion range of motion in PN patients has been implicated as a major cause of high planter pressure under the metatarsal heads8. This decrease unimpeded stance time and restrict the leg from progressing over the foot during the late stance phase of walking9. Decreased sensation, muscle weakness and excessive repetitive mechanical pressure lead to breakdown of tissue and formation of plantar ulcers. These lesions often are followed by infection, gangrene and amputation10,11,12. Casts, accommodative orthotic devices, protective footwear and  modification of walking patterns may be useful for reducing forefoot peak plantar pressure in patients with PN13-17.

Foot pressure analysis is becoming more common as technology continues to develop. Benefit of plantar pressure monitoring is that pressure to specific areas of the foot can be measured and visualized18. The purpose of this study was to determine whether weight-bearing exercises are effective for reducing peak forefoot planter pressure and improving functional performance in patients with diabetic peripheral neuropathy.

 

MATERIALS AND METHODS

 

The study was conducted on 30 patients from both sexes (11 male, and 19 female) with clinically diagnosed peripheral neuropathy of diabetic origin and confirmed with electrophysiological examinations.

Inclusion criteria included: (1) Being between 30:50 years old, (2) A known history of diabetes mellitus treated by diet, oral hypoglycemic or insulin therapy, (3) Mild to moderate lower extremities symptoms (grade 2 or 3) consistent with Odusote classification of PN19, (4) Strength of the muscles of the lower limbs were not less than grade 3 and all patients had ability to walk household distances (6 m.) without assistance or an assistive device, (5) No ankle injuries in the six months before application of the study and (6) Willingness to participate in the study and had to be motivated to visit all measurements and treatment sessions.

The criteria for exclusion were as follows: (1) History or evidence on physical examination consistent with central nervous system dysfunction (hemiparesis, myelopathy, or cerebellar ataxia), (2) Severe musculoskeletal deformity such as pes cavus, scoliosis, limitation of ankle inversion/eversion range of motion (<10° combined range), (3) Lower extremities severe arthritis or pain. (4) Electrodiagnostic evidence of any diagnosis other than PN, (5) History of angina or angina equivalent symptoms (palpitation, chest pain, nausea, vomiting, sweating, shortness of breath with exercises), (6) Symptomatic postural hypotension, (7) Gastrointestinal symptoms: recurrent constipation, diarrhea, fecal incontinence, (8) Autonomic bladder symptoms as retention or dribbling of urine, (9) History or evidence on physical examination of planter skin pressure ulcer, (10) Evidence of chronic diabetic complications e.g. ketoacidosis, (11) Severe hypoglycemic attacks, (12) Evidence of any other systemic, malignant diseases, alcohol abuse, neurotoxin medications or signs of autonomic neuropathy or peripheral vascular diseases, (13)  Obesity.

 

Instrumentation:

Mat foot scan pressure assessment system (Tekscan, Inc. USA, 1998) was used to  measure peak forefoot planter pressure. It consists of a force platform based system connected to computer system. The image of foot strike appears on the computer screen.

 

Procedures:

All patients  signed a written informed consent.

[1]           Evaluation protocol:

All patients were subjected to:

1-        Detailed history including: age, duration of diabetes and presence of peripheral neuropathy.

2-        Recording of patient's height and weight.

3-        Full neurological examinations with special emphasis on:

-     Motor examinations including (inspection, muscle strength of the lower limbs, muscle tone and deep reflexes).

-     Sensory examinations including superficial and deep sensations.

4-        Laboratory investigations to assess the diabetic state including: fasting blood sugar, glucosylated haemoglobin, urine analysis besides renal and liver function tests.

5-        Electrophysiological examinations including: sural response and peroneal or tibial responses.

6-        Peak forefoot planter pressure was measured for all patients pre and post treatment program using Mat scan pressure assessment system .Peak pressure (N/Cm2) under forefoot was calculated by averaging three steps, not including the first and last steps. Three successive walking trials were averaged19. The patient was instructed to walk with bare foot and with his own self selected walking speed to more accurately reflect his planter pressure during daily activity. Peak pressure under the forefoot (Rt. & Lt.) was calculated using the peak pressure mode of software and compared pre and post treatment program within each group and between both groups.

7-        Functional abilities were measured pre and post treatment by time scored (second) activities which are a series of reliable, timed items that stimulate a variety of basic activities of daily living including ascending and descending stairs, standing up from a chair, standing up from lying supine on a physical exercise table and walking six meters with comfortable speed and as fast for 50 meters. Low scores indicate better performance.

 

[2]           Treatment protocol:

The patients received exercises program five times a week for 12 weeks. They were divided into two equal groups: control group (G1) and study group (G2). Both groups received traditional physical therapy program in the form of :

1.         Warm-up of ten minutes of ergometer cycling and active free ankle range of motion from setting position.

2.         Stretching exercises for the lower extremities muscles for ten minutes.

3.         Repeated contraction technique for the muscles around the ankle joint for ten repetitions and two minutes rest in between.

4.         Gait training: Instruct the patient to reduce plantar pressure under the forefoot (21) (gait with foot flat throughout the stance phase; with limited toe off and increasing the length of the heel strike and midstance periods) for six meters in front of mirror. This repeated ten times with rest two minutes in between each trail.

 

The study group received additional exercises program (weight-bearing exercises program)22,23 included:

1.      Barbell squat position (via closed chain exercises for thigh muscles): A board of 2 cm. thick elevating the heels of the patient, thus facilitating  increased weight over heels. The patient was instructed to keep the back upright with the feet at approximately 20° of external rotation and shoulder width apart. A mirror was placed two meters in front the patient to enable visual feedback. The patient performed two warm-up squatting and then, was instructed  to squat with knee flexion about 45° and stand without using upper extremities as much as possible. This position is repeated ten times with a set of  two minutes rest.

2.      Bipedal inversion and eversion (closed chain active ankle exercises): In this exercises, patient's center of mass was sifted  to strengthen ankle invertors and evertors. Support was used as necessary. These exercises started with ten repetitions and increased to 15 after five sessions with two minutes rest. 

3.      Bipedal toes raise (lifting the forefoot as one does to balance on a heels). This exercise was performed as quickly as possible, using support as necessary for 12 repetitions with rest of two minutes and increased to 15 after five sessions.

4.      Unipedal toe raises. This is performed quickly for five repetitions and increased to ten repetitions after five sessions and then to two sets of ten after ten exercise sessions.

5.      Unipedal inversion and eversion. The patient inverted and everted the foot while standing on it to challenge balance. This exercise started with one sit of five repetitions in each direction and increased to ten repetitions after five sessions.

6.      Unipedal balance for time. This was performed  three trials on each foot.

 

Statistical analysis:

Data were summarized using mean ± SD. Paired t-test was used for pre and post comparisons within each group. Student's t-test for independent groups was used for comparisons of difference scores between groups. P-values were considered significant if <0.05.

 

RESULTS

 

Table (1) shows some demographic characteristics of the studied sample. Both groups were matched in their age, weight, height, duration of diabetes and peripheral neuropathy and fasting blood glucose level. There were no significant difference between the patients in the two groups.

Results of time scored activities (sec.) of both patient groups are listed in table (2). The values changed significantly from pre to post treatment program in the study group (G2) while there was no significant improvement in the control group (G1) after treatment. Comparisons between both groups indicated that these activities improved statistically in the study group (G2) compared to the control group (G1).

Values of peak forefoot planter pressure (N/cm2) decreased significantly in both groups (G1 & G2) after treatment program. Comparisons of both groups revealed significant reduction of forefoot planter pressure in the study group (G2) compared to the control group (G1) as illustrated in table (3) and fig. (1).


Table 1. The demographic data of the patients (G1 & G2) 

 

 

 

G1

Mean ± SD

G2

Mean ± SD

P-Value

Age (Years)

42.46±5.65

44.64±6.0

0.12

Weight (Kg.)

77.40±9.7

80.40±7.8

0.46

Height (m.)

1.68±0.07

1.73±0.08

0.18

Fasting blood glucose (mg/dl)

200±9.6

196.5±10.1

0.32

Duration of diabetes (years)

8.8±6.10

9.12±7.2

0.22

Duration of peripheral neuropathy (years)

2.8±2.10

1.11±2.3

0.15

 

 SD = Standard deviation                                Significant* at P< 0.05

 Table 2. Outcome measures of functional performance (sec.) changes in both groups (G1 & G2) pre and post treatment program

 

Activity (Sec.)

 

G1

Mean ± SD

G2

Mean ± SD

P-Value

Up and down stairs

Pre

94.30±8.60

91.90±5.90

0.32

P-value

0.10

0.00*

 

Post

80.00±2.10

61.10±5.20

0.01*

Standing up from a chair

Pre

60.10±3.20

58.50±3.80

0.07

P-value

0.10

0.00*

 

Post

52.30±8.60

39.00±10.20

0.01*

Standing up from supine

Pre

70.37±3.70

71.50±2.80

0.10

P-value

0.07

0.00*

 

Post

60.90±1.20

55.7±4.10

0.00*

Walking 6m. (Comfortably)

Pre

101.10±2.80

99.53±1.60

0.18

P-value

0.06

0.00*

 

Post

94.90±1.90

75.80±4.70

0.00*

Walking 50m. (fast)

Pre

142.20±6.10

139.3±6.10

0.20

P-value

0.09

0.00*

 

Post

129.70±2.70

82.30±6.60

0.00*

 

Significant*

at P< 0.05

SD

= Standard deviation

m.

= Meter

Sec..

= Second

Table 3. Comparisons of peak forefoot planter pressure (N/cm2) (Rt. & Lt.) in both groups (G1 & G2) pre and post treatment.

 

 

G1

Mean±SD

G2

Mean±SD

P-Value

Rt.

Pre

66±4.5

69±5.3

0.22

P-value

0.01*

0.000*

 

Post

49±5.3

29±6.7

0.000*

Lt.

Pre

57±6.6

60±7.2

0.35

P-value

0.02*

0.000*

 

Post

40±7.5

21±4.3

0.000*

Significant*  at P< 0.05               SD= Standard deviation

Rt.= Right                                     Lt.= Left

 

 

 

 

Fig. (1): Mean values of forefoot planter pressure (Rt. & Lt) pre and post treatment

in both groups (G1 and G2).

 

 


DISCUSSION

 

Foot ulcers and risk of falls are problems for patients with peripheral neuropathy of diabetic origin which may result in disability and may lead to amputation of the lower extremities24. Reducing forefoot peak planter pressure is a primary focus of prevention of these problems16. This study is a clinical trial to evaluate the effects of weight bearing exercises on forefoot planter pressure in diabetic neuropathy patients. The data showed reduction in peak forefoot planter pressure in both groups (study and control) after treatment program while this reduction was statistically significant in the study group compared to the control group.

Reduction of planter pressure in the study group was associated with improvement in functional performance after weight-bearing exercises program for the muscles of lower limbs. This may be due to neural adaptation such as increased motor unit activity of prime mover muscles and improved co-ordination i.e. appropriate changes in the activation of synergists and antagonists25. Exercises of weight-bearing for the lower extremities maximized firing of Ia muscle spindle afferents thought to mediate joint proprioception and stimulate nociceptive afferents26. This increased threshold to motion sense associated with increased center of pressure variance and improve postural control22.

These results agree with the results of Hickson et al.27, who demonstrated that full motor activation occurs in multi-joint exercises, thus the large gains of strength and functional activities observed in closed chain exercises. In addition, these closed chain exercises proved to increase motor performance tests which is comparable with the improvement by open chain exercises28. Otaviani et al.29, suggested that the nervous system learns how to use the muscle in an optimal way in multi-joint training more rapidly than single joint exercises due to increase stretch sensitivity of muscle spindle network.

Linss et al.12 and Hasting et al.19, concluded that improvement of dorsiflexion range of motion as a result of strengthening of dorsiflexors, evertors, invertors and lengthening of tendoachillis result in reduction in peak forefoot pressure. Furthermore, Salsich et al.30, demonstrated that an increase in muscle cross sectional area and improvement in performance of muscles acting on the ankle joint with completion of resistance program have been reported in individuals who have diabetic peripheral neuropathy without associated complications.

The results of the control group also revealed significant reduction in peak forefoot planter pressures. These results agree with the previous studies6,9,19,21 which reported that gait strategy can influence planter pressure. The heel and midfoot bear no weight of the body during the gait cycle in the diabetic peripheral neuropathy patients and high pressure under the forefoot occur9. One method for reducing peak forefoot planter pressure is to spread weight-bearing forces over the entire planter aspect of the insensitive foot. Modification of gait pattern results in an increase in heel peak planter pressure and decrease forefoot peak planter pressure31.

This significant reduction in peak forefoot planter pressure after gait training may be due to decreased walking speed as walking speed affects the vertical ground reaction force. It was reported that the vertical ground reaction force increased as walking cadence increased32,33.

 

Conclusion

A brief, weight-bearing exercises program designed to improve distal and proximal lower extremities strength reduced peak forefoot planter pressure and improved functional performance in patients with diabetic peripheral neuropathy.

 

REFERENCES

 

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2.      Bosch CG, Gilsing MG, Lee SG, Richardson JK Miller JA; Peripheral neuropathy effect on ankle inversion and eversion detection thresholds, Anch Phys Med Rehbi , 76:850-6, 1995.

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5.      Ducic I, Short kw,  and Dellon AL; Relationship between loss of pedal sensibility, balance, and falls in patients with peripheral neuropathy, Ann Plast Surg,52(6):535-40,2004.

6.      Mueller MJ, Salsich GB and Bastian AJ; Differences in the gait characteristics of people with diabetes and metatarsal ambulation compared with age matched controls, Gait Posture, 7:200-6, 1998.

7.      Deursen V; Mechanical loading and off- loading of the planter surface of the diabetic foot .Clin Infect Dis., 39(2); 87-91, 2004.

8.      Delbridge L., Perry P and Marr S; Limited joint mobility in the diabetic foot: relationship to neuropathy ulceration, J Diabetic Med, 15:113-18, 1998.

9.      Mueller MJ, Minor SD, Sahrmann SA, Schaaf JA, and Strube MJ; Differences in the gait characteristics of patients with diabetes and peripheral neuropathy compared with age matched controls, Phys Ther; 74:299-308, 1994.

10.    Mueller MJ, Diamond JE, Delitto A, and Sinacore DR: In sensitivity, limited joint mobility, and planter ulcers in patients with diabetes mellitus, Phys Ther, 69, 453-9, 1989.

11.    Linss, Lee Th, and Wapner KL; Planter forefoot ulceration with equinus deformity of the ankle in diabetes patients: the effect of tendo-Achilles lengthening and total contact casting, J Orotho, 19: 465-75, 1996.

12.    Defen L, and Liner B; Diffusion of ulcers in the diabetic foot is promoted by stiffening of planter muscular tissue under excessive bone compression, J Ortho.,33(9);999-1012,2004.

13.    Albert S, and Rinoie C; Effect of custom orthotics on planter pressure distribution in the pronated diabetic foot, J. Foot Ankle surgery, 33 (6): 598-604, 1994.

14.    Donaghue VM, Sarnow MR and Giutini JM, Longitudinal in-shoe foot pressure relief achieved by specially designed foot wear in high risk diabetic patients, Diabetes Clin Pract., 11:109-21, 1996.

15.    Chraang G, Patil KM, Parivalavan R, and Visvanathank K; Effect of foot sole hardness, thickness and footwear on foot pressure distribution parameters in diabetic neuropathy, J Diabetes Care ,25(6);1066-70,2002.

16.    Anmstrong DG, Lavery LA, and Bushman TR; Peak foot pressure influence healing time of diabetic ulcer treated with total contact casts, J Diabetes care, 35:1-5, 1998.

17.    Kastenbauer T, Sokal G, Auinger M, and I Rsigler K; Running shoes for relief of planter pressure in diabetic patients, J. Diabet Med, 15:518-522 , 1998.

18.    Boulton AJ: Hardisty CA and Bett, RP; Dynamic foot pressures and other studies as diagnostic aids in diabetic neuropathy, J. Diabetic Care; 32:67-71, 2004.

19.    Hastings MK, Muller MJ, Sinacore DR, Salisch GB, Engrberg IR and Johnson JF; Effects of tendoachilles lengthening procedure on muscle function and gait characteristics in patients with diabetes mellitus, J Orthop Sports Phys Ther; 30 (2): 85-90, 2000.

20.    Moxley RT, Functional testing, Muscle Nerve; 13:526-90, 1990.

21.    Kwon OY and Mucller J Walking patterns used to reduce forefoot planter pressure in people with diabetic neuropathies, Phys Ther, 81 (2), 828-35, 2001.

22.    Augustsson J, Esko A, THomee R and Savntesson U; Weight training of the thigh muscles using Closed VS. Open kinetic chain exercises: A comparison of performance enhancement, JOSPT, 27 (1); 3-8, 1998.

23.    Richarson JK, Sandman D and Vela S; A; Focused exercise regimen improves clinical measures of balance in patients with peripheral neuropathy, Anch Phys Med Rehabil, 82; 205-209, 2001.

24.    Mansour L, Abd El-Kader A, Abd El-Ghaffar S, and Sobhi L; Peripheral nerve dysfunction in children and adolcents with type I diabetes mellitus, Egypt J Neurol Psychiat Neurosurg, 37 (2): 221-228, 2000.

25.    McNevin NH, Wulf G and Carlson C; Effects of attentional focus, self control and dyad training on motor learning: Implications for physical rehabilitation, Phys. Ther., 80 (4); 373-385, 2000.

26.    Schneider SH and Ruderman NB; Exercises for diabetic patients with loss of protective sensation, J. Diabetic Care, 32;76-82, 2004.

27.    Hickson R, Hidakea K and Foster C., Skeletal muscle fiber type, resistance training and strength related performance, Med Sci Sports Exerc, 7; 989-992, 1997.

28.    Sleivert G, Backus R and Wenger H; The influence of strength training sequence on multijoint power output, Med Sci Sports Exerc, 18:1725-31, 1998.

29.    Otaviani RA, Miller IA and Wajtys EM: Inversion and eversion strength in the weight-bearing ankle, Am Sports Med, 29 (2); 219-225, 2001.

30.    Salsich GB, Brown M and Muller M: Relationships between planter flexor muscle stiffness strength and range of motion in subjects with diabetics peripheral neuropathy compared to age matched control, J Ortho Sports Phys The, 30 (8): 473-483 r, 2000.

31.    Mueller MJ, sinacore DR, Hoogestrate S, and Daly L; Hip and ankle walking strategies; effect on peak planter pressure and implications for neuropathic ualceration, Arch Phys Med rehabil, 1994, 75;1996-2000, 1994.

32.    Zhu H, Harries GF and Wertsch II; The effect of walking cadence on planter pressure, Arch Phys Med Rehabil, 72; 1000-5, 1995.

33.    Cook TM Farrell KP and Carey LA; Effects of restricted knee flexion and walking speed on the vertical ground reaction force during walking, J, Ortho Sports Phys Ther; 25:236-244, 1997.

 

 

الملخص العربى

 

تأثير تمرينات تحمل ثقل الجسم على ضغط كف القدم الأمامى فى مرضى اعتلال الأعصاب الطرفية

الناتج عن مرض السكر البولى

 

أجريت الدراسة على ثلاثين مريضا ممن يعانون من اعتلال الأعصاب الطرفية من النوع الحسى الحركى الناتج عن مرض السكر البولى. وقد خضع كافة المرضى للفحص الطبى الشامل مع فحص الجهاز العصبى وكذلك الأبحاث المعملية لاستبعاد الأسباب الأخرى المؤدية لخلل الأعصاب الطرفية. تم تقسيم المرضى الى مجموعتين متساويتين عدديا وتم علاج المجموعتين بمجموعة تمرينات شد وتقوية للعضلات المحيطة بالفخذ والكاحل مع تدريب للمشى لتوزيع الضغط على كافة أجزاء القدم بدلاً من الجزء الأمامى فقط. كما أضيفت مجموعة تمرينات لتحمل ثقل الجسم للمجموعة الثانية وذلك لمدة 12 أسبوع بمعدل 5 أيام فى الأسبوع وتم قياس ضغط كف القدم الأمامى لجميع المرضى قبل وبعد العلاج. وأسفرت النتائج عن تحسن الضغط فى كلا المجموعتين بعد العلاج إلا أنه يوجد فرق إحصائى بين المجوعتين لصالح المجموعة الثانية (مجموعة الدراسة) عنة فى المجموعة الأولى (المجموعة الضابطة) وارتبط هذا الفرق الإحصائى بتحسن فى الأداء.



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