Volume 87, Issue 5 , Pages 710-716, May 2006
Effects of Ankle-Foot Orthoses on Ankle and Foot Kinematics in Patient With Ankle Osteoarthritis
Article Outline
Abstract
Huang Y-C, Harbst K, Kotajarvi B, Hansen D, Koff MF, Kitaoka HB, Kaufman KR. Effects of ankle-foot orthoses on ankle and foot kinematics in patient with ankle osteoarthritis.
Objective
To determine if different foot orthoses have a similar effect on foot kinematics in subjects with ankle osteoarthritis (OA) when walking on various ground conditions.
Design
Within-subject comparisons study.
Setting
Biomechanics research laboratory.
Participants
Thirteen subjects with unilateral ankle OA.
Interventions
Custom-made ankle-foot orthosis (AFO), rigid hindfoot orthosis (HFO-R), and articulated hindfoot orthosis (HFO-A) were used by subjects when walking on level, ascending and descending ramp, and side-slope conditions.
Main Outcome Measures
The range of motion of the hindfoot (calcaneus relative to tibia) and forefoot (metatarsal relative to calcaneus) was measured using an 8-camera motion analysis system.
Results
The AFO and HFO-R provided the best sagittal plane hindfoot motion restriction over all ground conditions (P<.001). The HFO-R allowed the greatest sagittal plane forefoot motion when walking over level (P=.01) and side-slope (P<.02) conditions, the greatest frontal plane forefoot motion walking down the ramp (P=.003), and the greatest transverse plane forefoot motion when walking over level (P=.011) and ramp-ascending conditions (P=.005). The HFO-A restricted motion of the unaffected joint and did not effectively restrict hindfoot motion.
Conclusions
The HFO-R not only provides selective restriction to the ankle-hindfoot motion, but also allows sufficient forefoot motion compared with the AFO. We consider the HFO-R to be the best option of all tested orthoses for treating patients with ankle OA pain arising from ankle motion.
Key Words: Ankle , Orthotic devices , Osteoarthritis , Range of motion, articular , Rehabilitation
OSTEOARTHRITIS IS AMONG THE MOST common disabilities in the United States. In a study of 500 patients, osteoarthritis (OA) was found in 41% of knees, 19% of hips, and 4% of ankles.1 Although the incidence of ankle OA is lower than the hip or knee OA, patients with ankle OA have significant problems with ambulation.2
Patients with ankle OA usually complain about pain located over the anterior aspect of the ankle joint and morning stiffness.3 Conservative treatments for arthritic pain consist of nonsteroidal anti-inflammatory medications, intra-articular steroid injections, shoe modification, ambulatory aids, and foot orthoses.3, 4, 5 A standard nonsurgical treatment indicated for ankle arthritis is the use of an ankle-foot orthosis (AFO). An AFO controls joint motion and alignment of the foot and ankle and reduces OA pain.5, 6
Sources of ankle OA pain are stretching of the joint capsule, increased pressure in subchondral bone, and anterior impingement induced by osteophytes which are related to ankle joint motion.5, 7 When the talus is kept in neutral position during gait, the maximal contact area of the ankle joint is achieved and the pressure of the joint is decreased.8, 9 According the pathogenesis of OA pain, overloading is an important factor to induce the arthritic pain.5 Thus, the use of an optimal AFO to support the talus in the neutral position and to limit the ankle motion during gait is a reasonable treatment alternative to reduce OA pain arising from ankle motion.
Previous studies have evaluated the effect of the AFO on gait in healthy subjects, subjects diagnosed with rheumatoid arthritis (RA), and subjects with pedal OA. Kavlak et al10 proved the positive effects of foot orthoses on pain relief, step and stride length, and energy expenditure in patients with RA. Nester et al11, 12 quantified the effects of orthoses that reduced either supination or pronation on gait kinematics and kinetics during normal gait. Woodburn et al13, 14 showed that foot orthosis intervention resulted in pain reduction and deformity correction for RA patients. Thompson et al15 investigated orthotic therapy to treat pedal OA patients with pain. They concluded that OA patients could get longer pain relief by wearing orthotic devices. None of these previous studies has quantified the motion restriction imposed by different types of orthoses in patients with ankle OA.
The purpose of this study was to evaluate the triplanar ankle range of motion (ROM) restriction in patients with ankle OA who wore 3 different types of AFOs (custom-made AFO, rigid hindfoot orthosis [HFO-R], articulated hindfoot orthosis [HFO-A]) compared with those wearing a shoe without an orthosis (unbraced) and walking over various ground conditions. We hypothesized that these orthotic devices provided a similar ROM restriction of the ankle and foot. The results from this study may be useful for clinical decision-making concerning the optimal orthosis for treating patients with OA pain related to ankle motion.
Methods
Participants
We enrolled 13 subjects (7 men, 6 women; average age, 51±17y; range, 27–78y) in this study: 10 subjects had posttraumatic ankle OA and 3 subjects had primary degenerative ankle OA. These subjects were included if they had unilateral ankle OA without any concomitant arthritis in any other lower-extremity joints. They were diagnosed by clinical symptoms and radiographic findings with osteophytes or ankle joint space narrowing. These patients were referred from physicians in the Department of Orthopedic Surgery at Mayo Clinic. Patients who had previous arthrodesis, joint replacement of the lower extremity, or other systemic or neuromuscular disorders affecting gait were excluded from the study.
Procedures
We tested all subjects over the following ground conditions: walking on a level surface of 10-m length, ascending and descending a 10° ramp of 2.4-m length, walking on a 10° side slope of 6-m length having the ankle with arthritis lower than the unaffected side (side-slope low), and walking on the 10° side slope having the ankle with arthritis higher than the unaffected side (side-slope high). We chose these multisurface ground conditions to simulate everyday walking conditions. Subjects walked over these ground conditions while wearing a standard shoea without an orthosis and also while wearing 3 types of AFOs within this shoe. The braces tested in this study were a solid AFO, an HFO-A, and an HFO-R (fig 1). All orthoses were custom made for each subject by a certified orthotist.b The proximal trim line of AFO was inferior to the popliteal fossa and the distal trim line was proximal to the metatarsal heads. The proximal trim line of the HFO-R was inferior to the bulk of the gastrocnemius muscle bellies and distal trim line at the distal end of the heel fat pad. The proximal trim line of the HFO-A was inferior to the bulk of the gastrocnemius muscle bellies, while the distal trim line was proximal to the metatarsal heads. Gait analysis for each ground condition and shoe and orthosis condition was performed on each subject. The order of testing of shoe and orthosis (shoe alone, AFO, HFO-A, HFO-R) and ground conditions (level, ramp-up, ramp-down, side-slope high, side-slope low) was randomized. Kinematics were measured using retro-reflective markers based on the Akron marker set.16 Eleven markers were placed over bony landmarks on the distal tibial crest (4 and 6cm proximal to the medial malleolus), medial and lateral malleoli, calcaneus (posterior process, the medial and lateral sides), and the bases and the heads of the first and fifth metatarsals rays (fig 2). We made three holes in each orthosis and in the shoe to allow placement of the calcaneal and metatarsal markers directly on the skin. Mechanical tests of the orthoses demonstrated that the holes did not significantly alter orthosis stiffness.17 A static calibration test was taken before the walking trials to establish an anatomic neutral position.18 The subjects then ambulated at least 3 times for each ground condition at their self-selected walking velocity. During ambulation, an 8-camera motion analysis systemc was used to track the position of the markers. The video system was configured and calibrated for each ground condition.
Fig 1.
Three different types of custom-made foot orthoses (from left to right): an AFO, an HFO-R, and an HFO-A, were evaluated in this study.
Fig 2.
A modification of the Akron marker set was used to track foot motion while wearing orthotic devices evaluated in the study.
Data Analysis
We used custom-written software to calculate 3-dimensional kinematics between the tibia and hindfoot and between the hindfoot and forefoot. The stance phase of 1 gait cycle from each of the 3 data trials was averaged and used in the statistical analysis.
For statistical analysis, we performed a repeated-measures analysis of variance (ANOVA) to evaluate any differences in ROM enabled by each orthotic device.d The repeated-measures component of the statistical analysis was necessary because each subject used each orthotic device when walking on each ground condition. Statistical significance was set at P less than .05. A post hoc Student-Neuman-Keuls multiple comparison test was performed for all orthoses evaluated for each ground condition when statistical significance was achieved.
Results
In the statistical analysis, we found that no single orthotic device consistently constrained the hindfoot motion in all planes while not impeding forefoot motion, for each ground condition. The total joint ROMs of the hindfoot and forefoot segments are given in Fig 3, Fig 4, Fig 5, Fig 6, Fig 7. Each figure displays the ROM (average ± standard deviation [SD]) of these 2 segments for the sagittal, frontal, and transverse planes, for each orthosis, and for 1 ground condition. The results from the post hoc Student-Neuman-Keuls tests are displayed on the figures if significance was found from the ANOVA analyses.
Fig 3.
The sagittal, frontal, and transverse planes ROM (average ± standard deviation [SD]) of the (A) hindfoot and (B) forefoot in ankle OA patients using 3 types of orthoses when walking on a level walkway. *Significant difference (P<.05).
Fig 4.
The sagittal, frontal, and transverse planes ROM (average ± SD) of the (A) hindfoot and (B) forefoot in ankle OA patients using 3 types of orthoses when walking down a ramp. *Significant difference (P<.05).
Fig 5.
The sagittal, frontal, and transverse planes ROM (average ± SD) of the (A) hindfoot and (B) forefoot in ankle OA patients using 3 types of orthoses when walking up a ramp. *Significant difference (P<.05).
Fig 6.
The sagittal, frontal, and transverse planes ROM (average ± SD) of the (A) hindfoot and (B) forefoot in ankle OA patients using 3 types of orthoses when walking on the side-slope high condition. *Significant difference (P<.05).
Fig 7.
The sagittal, frontal, and transverse planes ROM (average ± SD) of the (A) hindfoot and (B) forefoot in ankle OA patients using 3 types of orthoses when walking on the side-slope low condition. *Significant difference (P<.05).
Level Ground Condition
The AFO allowed the least sagittal hindfoot motion. The ROM of the AFO was significantly less than that of the standard shoe and the HFO-A (P=.000). No significant differences were found in the frontal and transverse planes among the shoe and orthosis conditions (see fig 3A).
The HFO-R allowed the greatest sagittal plane forefoot motion (P=.01) and a significantly larger ROM than the HFO-A and AFO in the transverse plane (P=.011). No significant differences were found in the frontal plane among the shoe and orthosis conditions (see fig 3B).
Ramp-Down Ground Condition
When descending the ramp, the sagittal plane hindfoot motion was similar in the HFO-R and AFO conditions, but the motion was significantly less than in the standard shoe and the HFO-A conditions, which were similar to each other (P<.000). All orthoses significantly reduced the frontal plane hindfoot motion relative to the standard shoe (P=.014). No significant differences were found in the transverse plane among the shoe and orthosis conditions (see fig 4A).
When descending the ramp, the HFO-R allowed the largest sagittal plane forefoot motion. This was significantly greater than the HFO-A condition (P=.01). In addition, the HFO-R was associated with the greatest frontal plane forefoot motion (P=.003). Transverse plane forefoot motion was decreased in the HFO-A and AFO conditions as compared with the shoe-only condition (P=.022) (see fig 4B).
Ramp-Up Ground Condition
When ascending the ramp, the sagittal plane hindfoot motion in the HFO-R condition was similar to the AFO condition. Both conditions were significantly less than the sagittal plane hindfoot motion of the standard shoe and the HFO-A conditions, which were similar to each other (P<.000). All orthoses significantly reduced frontal plane hindfoot motion relative to the standard shoe (P=.009). No significant differences in hindfoot motion were found in the transverse plane among the shoe and orthosis conditions (see fig 5A).
When ascending the ramp, the HFO-R allowed significantly greater sagittal plane forefoot motion than the HFO-A (P=.01). The HFO-R was also associated with a significantly greater transverse plane forefoot motion than the HFO-A and AFO (P=.005). No significant differences were found among the shoe and orthosis conditions in the frontal plane forefoot motion (see fig 5B).
Side Slope Having the Arthritic Ankle Higher Than the Normal Side
In the side-slope high condition, the sagittal plane hindfoot motions associated with the HFO-R and AFO conditions were similar and significantly less than the motions associated with the standard shoe and the HFO-A, which were similar to each other (P<.000). All orthoses significantly reduced frontal plane hindfoot motion relative to the standard shoe (P<.000). No significant differences in the transverse plane hindfoot motion were found in any shoe and orthosis conditions (see fig 6A).
In the side-slope high condition, the HFO-R allowed the greatest sagittal plane forefoot motion (P=.018). Transverse plane forefoot motion was similar in the standard shoe and HFO-R conditions were significantly greater than the HFO-A and AFO conditions, which were similar to each other (P=.004). No significant differences were found in the frontal plane forefoot motion among the shoe and orthosis conditions (see fig 6B).
Side Slope Having the Arthritic Ankle Lower Than the Normal Side
In the side-slope low condition, the sagittal plane hindfoot motion was similar in the HFO-R and AFO conditions and was significantly less than the standard shoe and the HFO-A conditions, which were similar to each other (P<.000). No significant differences were detected in the frontal and transverse plane hindfoot motion in any shoe and orthosis condition (see fig 7A).
In the side-slope low condition, the HFO-R allowed the greatest sagittal plane forefoot motion in all shoe and orthosis conditions (P=.001) and significantly greater transverse plane motion when compared with the AFO condition (P=.036). No significant differences in the frontal plane forefoot motion were associated with any shoe and orthosis condition (see fig 7B).
Rigid Hindfoot Orthoses
In the level condition (see fig 3), the HFO-R and AFO provided similar restriction of the hindfoot. The HFO-R allowed the greatest sagittal forefoot motion (P=.01) and significantly greater transverse plane forefoot motion than the AFO and HFO-A (P=.011). We recommend the HFO-R as the best choice for selectively restricting ankle motion when walking on level surfaces.
In the descending ramp condition (see fig 4), the HFO-R and AFO were the best at restricting sagittal hindfoot motion (P<.000). All orthoses were effective in limiting frontal plane forefoot motion (P=.014). The HFO-R allowed the greatest frontal plane forefoot motion (P=.003), and significantly greater sagittal plane forefoot motion than the HFO-A (P=.01). We recommend the HFO-R as the best option for selectively restricting ankle motion when walking down the ramp.
In the ascending ramp condition (see fig 5), the HFO-R and AFO restricted sagittal hindfoot motion the most (P<.000). All orthoses were effective in limiting frontal plane hindfoot motion (P=.009). The HFO-R provided significantly greater transverse plane forefoot motion than the AFO (P=.005) and also allowed significantly greater transverse (P=.005) and sagittal plane (P=.01) forefoot motion than the HFO-A. We recommend the HFO-R as the best choice for selectively restricting ankle motion when walking up the ramp.
In the side-slope high condition (see fig 6), the HFO-R and AFO restricted sagittal plane motion of the hindfoot segment the most (P<.000), while all 3 orthoses decreased range in the frontal plane (P=.000). The HFO-R allowed the greatest motion of the forefoot segment in the sagittal plane (P=.018). The HFO-R and shoe provided the greatest motion of the forefoot segment in the transverse plane (P=.004). We recommend the HFO-R as the best choice for selectively restricting ankle motion when walking on the side-slope high condition.
In the side-slope low condition (see fig 7), the HFO-R and AFO provided the greatest restriction of hindfoot sagittal plane motion (P<.000), without any significant change in the frontal and transverse motions. The HFO-R allowed the greatest sagittal plane forefoot motion (P=.001) and allowed significantly greater transverse plane forefoot motion than the AFO (P=.036). We recommend the HFO-R as the best choice for selectively restricting ankle motion when walking on the side-slope low condition.
Based on these findings, the HFO-R has been supported as the optimal choice among the 3 orthoses evaluated in this study because it provides not only the best restriction of the hindfoot segment but also allows the greatest motion of the forefoot segment in all ground conditions.
Articulated Hindfoot Orthoses
In Fig 3, Fig 4, Fig 5, Fig 6, Fig 7, the HFO-A restricted sagittal hindfoot motion the least compared with the other braces in all ground conditions. Sagittal plane hindfoot motion using the HFO-A was larger than with the shoe alone, and no significant differences were found between the shoe and HFO-A conditions. The HFO-A significantly reduced the frontal plane hindfoot motion relative to the standard shoe in both the ramp (P=.014 and P=.009) and side-slope high (P<.000) conditions. The HFO-A provided similar forefoot motion restriction as provided by the AFO in all planes and ground conditions. The HFO-A restricted forefoot transverse plane motion to a greater extent when compared with walking with the shoe alone in the ramp-descending (P=.022) and the side-slope high conditions (P=.004). Therefore, the data demonstrated that the HFO-A not only restricted the unaffected adjacent joints, but also provided limited motion restriction of the hindfoot segment.
Discussion
In this study, we measured the kinematics of 3 types of orthoses and standard shoes worn by patients with ankle OA walking on level, side-slope, and ramp conditions. We compared the hindfoot and forefoot motion between the orthosis and shoe-only conditions to determine which orthosis could selectively restrict ankle joint motion.
Previous studies have proven that foot orthoses have decreased arthritic pain in patients with OA.15, 19 There are various sources for ankle OA pain. One previous study7 divided ankle OA pain sources into 2 categories: articular and nonarticular pain. The articular sources of ankle OA pain are related to joint motion, particularly at the end ROM of the affected ankle joint.5, 7, 20 Therefore, ankle OA pain arising from joint motion will be reduced when keeping the ankle and talus in the neutral position that provides the largest contact area and decreases articulating surface pressure in the ankle joint.5, 9, 21 We consider that limiting the ankle motion and keeping the ankle and talus in the neutral position could be achieved by using an optimal orthotic device.
Raikin et al22 studied the effect of different casts and braces on the ankle and hindfoot immobilization by using the prosthetic model. They found that molded AFO could provide the best sagittal and frontal motion resistance to ankle and hindfoot among all tested braces. Eils et al23 evaluated passive and rapidly induced stability of different ankle braces in patients with chronic ankle instability. The results of this study revealed that all tested ankle braces provided significantly greater triplanar hindfoot ROM restriction than the shoe-only condition. Our present study found a similar result. The rigid AFO (AFO, HFO-R) significantly restricted sagittal and frontal plane hindfoot motion compared with the shoe-only condition in patients with ankle OA for nearly all tested ground conditions.
Orthotic devices that not only limit motion of the affected joint but also allow normal motion of adjacent joints would be considered an ideal orthotic device for treatment of ankle OA. A custom-molded AFO immobilizes multiple joints of the foot, hindfoot, midfoot, and forefoot in a nonselective manner. Although a custom AFO is effective for relieving arthritic pain, some patients have difficulty with wearing compliance because of impaired foot function and proximal joint strain sensation.24 In addition, immobilization of the unaffected midtarsal joints and restricted forefoot motions may adversely affect sagittal and frontal plane balance during gait. Therefore, other orthoses have been designed, such as the HFO-R, to improve foot function.24 In our study, the results showed the HFO-R provided as good restriction of the hindfoot motion as the AFO in all ground conditions and also allowed better forefoot motion than the AFO in patients with ankle OA.
Crevoisier et al25 evaluated the effectiveness of the same 3 types of AFOs tested in the present study. Crevoisier evaluated the orthoses only on normal subjects walking on a level surface. The study found that the AFO and the HFO-R significantly restricted sagittal plane hindfoot motion when compared with the HFO-A and the shoe alone. Their result compares favorably with the present study, even though we evaluated subjects with ankle OA. However, the previous study also found that all 3 orthoses significantly restricted frontal plane hindfoot motion relative to the shoe-only condition. We did not have a similar result for the ankle OA subjects. An explanation of this difference may be that the hindfoot frontal plane ROM was already decreased due to the natural course of ankle OA before using the orthosis.
Conclusions
Gait analysis has been used to study the effects of different orthosis designs. These data can be used to offer the clinician objective evidence of which orthosis can provide better restriction to the ankle joint and less restriction to adjacent joints. In this study, we demonstrated that the HFO-A could not provide the same amount of restriction at the hindfoot as the AFO, but had a restriction to the forefoot segment similar to the AFO. The data also demonstrated that the HFO-R not only provides selective restriction to hindfoot motion but also allows sufficient forefoot segment motion relative to the AFO. This is beneficial if limiting ankle joint motion is desired without impeding overall foot function. We consider the HFO-R to be the optimal orthosis of all braces evaluated in this study for treating ankle OA pain related to ankle motion.
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- a New Balance 572; New Balance Athletic Shoe Inc, Brighton Landing, 20 Guest St, Boston, MA 02135-2088.
- b Prosthetic Laboratories of Rochester Inc, 121 23rd Ave SW, Rochester, MN 55902.
- c Motion Analysis Corp, 3617 Westwind Blvd, Santa Rosa, CA 95403-8227.
- d SAS Institute Inc, 100 SAS Campus Dr, Cary, NC 27513.
Supported by the National Institutes of Health (grant no. AR 44513).No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.
PII: S0003-9993(06)00050-5
doi:10.1016/j.apmr.2005.12.043
© 2006 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.
Volume 87, Issue 5 , Pages 710-716, May 2006
