FOOT & ANKLE INTERNATIONAL Copyright 2003 by the American Orthopaedic Foot & Ankle Society, Inc.
Outcome of Orthoses Intervention in the Rheumatoid Foot Yasemin Kavlak, P.T., Ms.C.∗ ; Fatma Uygur, P.T., Ph.D.∗ ; Cengiz Korkmaz, M.D.† ; Nilgün Bek, P.T., Ph.D.∗ Ankara, Turkey; Eskisehir, Turkey
The instability at the hind part of the foot may be accompanied by deformity in the forefoot, specifically hallux valgus and depression of metatarsal heads.3,5,9,24 The metatarsal heads are often the site of inflammation and eventually the metatarsophalangeal (MTP) joints dislocate; the proximal phalanges come to rest dorsally on the metatarsals and force the metatarsal heads downward. The fat pad under the metatarsal heads migrates dorsally, no longer providing protection for the metatarsal heads. Thick callouses may develop in this area. These are painful with weightbearing and may lead to ulceration. The long flexor and extensor muscles of the toes lose their normally balanced position and claw and hammer toe deformities may develop.5,9,24 In patients with rheumatoid arthritis, gait velocities are usually slower and periods of single limb stance are often shortened.6 It is usually possible to observe excessive eversion of the heel in midstance, indicating that the subtalar joint is remaining in excessive pronation. With a hallux valgus deformity, the patient tends to keep body weight posterior, causing a late heel rise and shortened single limb support. It is painful for the patient with hammer or claw toes and metatarsal head subluxation to perform the push-off phase of terminal stance. If the patient has subplantar spur and tendocalcaneal bursitis, he or she will complain of pain at initial heel contact.8 Orthoses are externally applied devices to support a joint or enhance its function. In arthritis, orthoses are prescribed to stabilize joints, provide better positioning, reduce pain, prevent deformity, and improve function.12 The general indications for prescription of orthoses in arthritis are: 1) joint stabilization, 2) joint positionings to avoid excessive stress, 3) pain reduction, 4) prevention of deformity, 5) improvement of function, 6) joint rest, 7) reduction of inflammation, 8) improved range of motion, and 9) pressure distribution. This study was carried out in a group of patients with rheumatoid arthritis to determine how the use of foot
ABSTRACT This study was carried out to determine the effect of foot orthoses on pain, gait, and energy expenditure in patients with rheumatoid arthritis. Eighteen patients were evaluated for these parameters. Each patient was given a foot insert or shoe modification suitable for his or her foot deformity. Following 3 months of orthosis use, a significant difference was found in regards to pain (p < .05), step length and stride length (p < .05), and physiological cost index (p < .05). The results suggest that foot orthoses are an important feature in the rehabilitation of the rheumatoid foot. Key Words: Rheumatoid Arthritis; Foot Deformity; Orthoses; Observational Gait Analysis INTRODUCTION
Rheumatoid arthritis (RA) affects between 0.3% and 1.5% of the population worldwide.20 Individuals frequently develop foot deformities unique to this disease. Weightbearing stresses through the pathologic tissue and joints may produce deformity and pain.5 The patient may not be able to tolerate ambulation activities. If treatment can be initiated to correct or stabilize deformities and provide relief, ambulation may be restored.1,5,15,16,21 In the foot affected by rheumatoid arthritis, as the midtarsal and subtalar joints become less stable, the head of talus shifts in a plantar and medial direction. ∗
Hacettepe University, School of Physical Therapy and Rehabilitation, Department of Orthotics and Biomechanics, Ankara, Turkey † Osmangazi University, Faculty of Medicine, Department of Rheumatology, Eskisehir, Turkey Corresponding Author: Nilgün Bek Hacettepe Universitesi Fizik Tedavi ve Rehabilitasyon Yüksekokulu Ortez ve Biomekanik Unitesi 06100 Samanpazari, Ankara, Turkey E-mail: nilgunbek@hotmail.com For information on prices and availability of reprints call 410-494-4994 X226.
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orthoses affects pain. The time – distance characteristics and energy expenditure of gait were also studied. MATERIALS AND METHODS
The subjects of this study were chosen among patients undergoing treatment in a rheumatology clinic on an outpatient basis. Criteria for patient selection were: 1) community walker, 2) treatment by rheumatologist, 3) no foot surgical procedures, 4) no exacerbation of disease for 3 months, and 5) informed consent to take part in this study. Eighteen patients with RA, 6 men and 12 women with a mean age of 49.7 ± 12.6 years, participated in the study. The demographic characteristics of the subjects are given in Table 1. The extra-articular findings of the patients are given in Table 2. The deformities were found by means of observational posture analysis and podoscopy. Podoscopy uses a sheet of plate glass on which a patient stands. A mirror, angled at 45◦ underneath, displays the weightbearing pattern (Table 3). The degree of pes planus was clinically assessed by means of grading the position of the scaphoid tubercle relative to a hypothetical line which extends from below the medial malleolus to the point where the metatarsophalangeal joint of the great toe rests on the floor (Feiss line).27 The hallux valgus angle of our patients ranged between 2◦ and 56◦ . Thirteen patients had hallux valgus exceeding 15◦ . The degree of Table 1: Demographic characteristics of subjects (N = 18) X ± SD Age (year) Height (cm) Body weight (kg) Education (years) Disease duration (years)
50 ± 13 162 ± 12 66 ± 13 7±4 8±7
Table 2: Extra-articular findings of subjects (N = 18)
Edema Erythema Metatarsophalangeal joint sensitivity Morning stiffness Rheumatoid nodule Fatigue (in activity) Fatigue (in rest) Callouses
n
%
13 3 15 15 2 14 9 8
72 17 83 83 11 78 50 45
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Table 3: Foot deformities of subjects (N = 18) Deformities
Unilateral n %
Bilateral n %
Pes planus Hallux valgus Hammer toe Forefoot inversion Forefoot eversion Splayed foot Metatarsophalangeal depression Pronation
1 4 1 — — — 2
6 22 6 0 0 0 11
14 5 3 — 3 8 7
78 28 17 0 17 44 39
—
0
10
56
hallux valgus was measured by radiographic evaluation. The hallux-metatarsophalangeal angle is formed by the intersection of the midlongitudinal axis of the first metatarsal and the proximal phalanx.19 Calluses were seen on the proximal interphalangeal joints and under the second, third, and fourth metatarsal heads. Following evaluation of the foot, patients were given orthoses made to meet their specific needs. The foot problems and orthoses applied for each patient are given in Table 4. Fifteen patients were given bilateral medial longitudinal arch supports with the aim of increasing the surface area of weightbearing and reducing tension under the plantar aponeurosis. This was also designed to shift weight towards the lateral side of the foot, consequently reducing pressure under the first metatarsal head. The medial longitudinal arch support was made from resilient material. The apex was located from under the sustentaculum tali to the navicular tuberosity and had a maximum height of 9 mm. Patients with flexible calcaneal and forefoot eversion were given medial wedges for the forefoot and heel. One patient used a medial heel wedge and three patients used medial heel and sole wedges to invert the heel and foot, thus relaxing the plantar aponeurosis and realigning the foot for even weightbearing. Patients with depression of the second, third, and fourth metatarsal heads were given metatarsal pads to relieve pressure from the metatarsal heads and to transfer the body weight to the commonly painless necks and shafts of the metatarsals. Nine patients were given metatarsal pads; in one patient, when this was not sufficient to relieve pain, a metatarsal bar was given under the shoe, and one patient was relieved of pain with a rocker bar which transferred the toe rocker function from the foot to the footwear ground interforce. Four patients who had flexible hammer/claw toes were treated with a bar lying on the proximal phalanges of the feet similar to using an extensor stop assembly for
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Table 4: Foot problems and orthoses applied for each patient No.
Problem
1
Pes planus, hammer toe, splayed foot, depression of second, third, and fourth metatarsal heads Pes planus, hallux valgus, splayed foot, depression of second, third, and fourth metatarsal heads Splayed foot Pes planus, hammer toe, splayed foot, hallux valgus, depression of second, third, and fourth metatarsal heads, calcaneal and forefoot eversion Hammer toe, hallux valgus, depression of second, third, and fourth metatarsal heads Pes planus, hammer toe, splayed foot, hallux valgus, depression of second, third, and fourth metatarsal heads, calcaneal and forefoot eversion Pes planus, hallux valgus, depression of second, third, and fourth metatarsal heads Pes planus, hallux valgus Pes planus, depression of second, third, and fourth metatarsal heads Pes planus, hallux valgus, splayed foot, depression of second, third, and fourth metatarsal heads, calcaneal and forefoot eversion Pes planus Pes planus, Pes planus, splayed foot Pes planus Pes planus Pes planus Pes planus, hallux valgus, splayed foot, depression of second, third, and fourth metatarsal heads, calcaneal eversion
2
3 4
5
6
7
8 9 10
11 12 13 14 15 16 17
Orthotic Approaches MLAS, metatarsal pad, dorsal bar MLAS, metatarsal pad
Metatarsal bar MLAS, metatarsal pad, dorsal bar, medial heel-forefoot wedge Metatarsal pad, dorsal bar
MLAS, metatarsal pad, dorsal bar, medial heel-forefoot wedge, custom-made shoes MLAS, metatarsal pad
MLAS MLAS, rocker bar, metatarsal pad MLAS, metatarsal pad, medial heel and forefoot wedge MLAS MLAS MLAS MLAS MLAS MLAS MLAS, metatarsal pad, medial heel wedge, custom-made shoes
MLAS, medial longitudinal arch support.
intrinsic minus deformity.7 The bar, made of polyform of about 1 cm in depth was installed into the inner surface of the vamp of the shoe. Finding the exact location took some time, but once it was established patients expressed instant relief (Fig. 1).25 All of the orthoses were custom-made. Thirteen patients were able to wear their inserts with normal shoes. Two patients were given extra-depth shoes. For two patients who were not relieved of their pain with extra-depth shoes and soft insoles, it was not possible
to use regular lasts; therefore, a plaster model of the feet of the patients was given to the shoemakers for manufacturing custom-made shoes to accommodate the ďŹ xed deformity. Procedure
The intensity of pain was assessed through the pain subscale of foot function index and the visual analogue scale. The patient was asked to mark the severity of foot pain along a horizontal visual analogue scale
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Fig. 1: Bar for metatarsophalangeal hyperextention.
for seven situations. Patients were asked how severe their pain was at its worst, before getting up in the morning, standing barefoot, walking barefoot, walking while wearing shoes, standing with shoes, and at the end of the day. The score for each item was based on the position of the patient’s mark along a horizontal 10-cm-long visual analogue scale (VAS) anchored by ‘‘no pain’’ and ‘‘worst pain imaginable.’’ The item scores were summed and then divided by the maximum number of items that the patient indicated were applicable. All patients were required to walk with the footwear to which they were accustomed for a distance of 15 m. Temporal distance values were obtained through footprints (Fig. 2). Subjects walked at a self-selected comfortable speed along a 15-m walkway. The measures were recorded from the center 7 m of the walkway to ensure a constant walking velocity. Three successive right and left footprints were analyzed. These six footprints were used to obtain four measurements of stride length, four measurements of step width, two measurements of right step length, two measurements of left step length, and six measurements of foot angle. The measurements were averaged for statistical analysis. We chose to count the number of steps taken in 1 minute to estimate cadence. This procedure was repeated three times and averaged for statistical analysis. Velocity can be calculated by Step Length × Cadence/60, but we chose to calculate velocity as the
time required for the subjects to walk a 100-m walkway. For calculating the physiologic cost index (PCI), patients were asked to walk with their regular footwear for a distance of 100 m at a brisk pace that did not cause strain and was perceived as comfortable by the subjects. A chronometer was used to measure the time that was required to walk 100 m. The subjects’ heart rate was recorded before starting to walk and during the last meter of walking. PCI is formulated as: PCI = (Heart Rate Walking − Heart Rate Resting)/ Velocity The unit of heart rate is beats per minute and velocity is meters per minute. Consequently PCI is measured in net beats per meter. The temporal distance characteristics of gait, pain severity, and PCI were evaluated when the patients first came to our unit and 3 months after they started using their custom-made orthosis. Data Analysis
Student t test for repeated measurements was used and p value was set up as .05 for statistical analysis of data with the SPSS for Windows Release 6.0 statistical packet program. RESULTS
There was a significant decrease in pain intensity reported by the patients following 3 months of orthosis
Fig. 2: Time distance characteristics of gait.
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Table 5: pre- and post-treatment assessment results
Right step length Left step length Stride length Right foot angle Left foot angle Step width Physiologic energy cost index (PCI) Visual analogue scale (VAS) wear (p < .05). When the pre- and post-treatment values of time –distance characteristics of gait obtained through footprints were compared, a statistically significant difference was found in regards to right and left step lengths and stride length in favor of post-treatment values (p < .05). No difference was found in regards to foot angle and base of support width (p > .05). Statistically significant difference was found in PCI values in favor of post-treatment values (p < .05) (Table 5). DISCUSSION
Estimating the energy expenditure of ambulation is essential for assessing gait efficiency and the potential benefits of lower limb orthoses.2,4,14 Energy consumption is related to the difference in heart rate between the resting condition and that measured during exercise.26 The PCI has been documented to demonstrate the same trend as VO2 and heart rate with walking velocity. It has been shown to be a reliable measurement of energy expenditure.17,22 Following a trial period of 3 months, a statistically significant decrease in the PCI was seen. Since the inserts and shoe modifications provided shock absorption, pain reduction, and support, it was possible to achieve comfortable forward progression of the extremities, resulting in a more energy-efficient gait. This result supports the use of inserts and shoe modifications in patients with RA for reducing the energy demands of gait. There was also an increase in step length, stride length, and consequently in walking velocity. The difference between pre- and post-orthoses intervention values in regards to step and stride length was significant (p < .05). This result is in accordance with similar studies.5,6,9,11,18,23 Locke et al. reported that arthritic patients demonstrated slower gait velocity and less single limb support time and a significant increase occurred in these values upon wearing an orthosis.11 In a study on healthy subjects, Volashin has shown that with viscoelastic shoe supports a decrease is
Before X ± SD
After X ± SD
p
41 ± 11 41 ± 11 76 ± 26 12 ± 4 12 ± 4 12 ± 4 0.3 ± 0.2 61 ± 25
51 ± 13 51 ± 15 102 ± 28 12 ± 4 12 ± 5 11 ± 4 0.2 ± 0.1 43 ± 22
< .05 < .05 < .05 > .05 > .05 > .05 < .05 < .05
attained in base of support area during gait.12 We did not find a decrease in step width. The base of support was not affected from use of modifications or inserts. Although the choice of shoe modifications and inserts are different in each of these reports, the common consequence is that appropriate orthosis intervention favorably alters time –distance characteristics of gait. The results of our study are consistent with former findings. There was a significant decrease in pain intensity reported by the patients following 3 months of using the orthosis (p < .05). These results show that orthoses intervention and shoe modifications can diminish the mechanical stresses on the afflicted parts of the foot and ankle and therefore give pain relief. This result is in accordance with other studies evaluating the effect of orthosis intervention on pain.10 – 13,18 CONCLUSION
Adequately designed foot orthoses combined with appropriate shoe modifications can bring functional improvement and pain relief to many patients with rheumatoid arthritis affecting the foot. REFERENCES 1. Benjamin, A; Hirschowitz, D: Surgery in rheumatoid arthritis. In: B Helal, D Wilson, eds, The Foot, Edinburgh, Livingstone, 1988, pp. 535 – 541. 2. Butler, P; Engelbrecht, M; Major, RE; Stallard, J; Patrick, JH: Physiological cost index of walking for normal children and its use as an indicator of physical handicap. Dev. Med. Child. Neurol. 26:607 – 612, 1984. 3. Cracchiolo, A: Rheumatoid arthritis. hindfoot disease. Clin. Orthop. 340:58 – 68, 1997. 4. Davies, JB: Use of heart rate in assessment of orthosis. Physiotherapy 63:112 – 114, 1977. 5. Dimonte, P; Light, H: Pathomechanics, gait deviations, and treatment of the rheumatoid foot. Phys. Ther. 62(8):1148 – 1156, 1982. 6. Fransen, M; Heussler, J; Margiotta, E; et al.: Quantitative gait analysis — comparison of rheumatoid arthritic and non-arthritic subjects. Austral. Physiother. 40(3):191 – 199, 1994.
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