The Journal of Bone and Joint Surgery 81:539-48 (1999)
© 1999 The Journal of Bone and Joint Surgery, Inc.
The Effect of Bracing on Varus Gonarthrosis*
A. KIRKLEY, M.D. ,
S. WEBSTER-BOGAERT, M.SC.,
R. LITCHFIELD, M.D.,
A. AMENDOLA, M.D.,
S. MACDONALD, M.D. ,
R. MCCALDEN, M.D. and
P. FOWLER, M.D., LONDON, ONTARIO, CANADA
Investigation performed at the Fowler Kennedy Sport Medicine Clinic, University of Western Ontario, London
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Abstract
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Background: The purpose of this study was to compare a custom-made valgus-producing functional knee (unloader) brace, a neoprene sleeve, and medical treatment only (control group) with regard to their ability to improve the disease-specific quality of life and the functional status of patients who had osteoarthritis in association with a varus deformity of the knee (varus gonarthrosis).
Methods: The study design was a prospective, parallel-group, randomized clinical trial. Patients who had varus gonarthrosis were screened for eligibility. The criteria for exclusion included arthritides other than osteoarthritis; an operation on the knee within the previous six months; symptomatic disease of the hip, ankle, or foot; a previous fracture of the tibia or femur; morbid obesity (a body-mass index of more than thirty-five kilograms per square meter); skin disease; peripheral vascular disease or varicose veins that would preclude use of a brace; a severe cardiovascular deficit; blindness; poor English-language skills; and an inability to apply a brace because of physical limitations such as arthritis in the hand or an inability to bend over.
Treatment was assigned on the basis of a computer-generated block method of randomization with use of sealed envelopes. The patients were stratified according to age (less than fifty years or at least fifty years), deformity (the mechanical axis in less than 5 degrees of varus or in at least 5 degrees of varus), and the status of the anterior cruciate ligament (torn or intact). The patients were randomly assigned to one of three treatment groups: medical treatment only (control group), medical treatment and use of a neoprene sleeve, or medical treatment and use of an unloader brace. The disease-specific quality of life was measured with use of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire (MACTAR), and function was assessed with use of the six-minute walking and thirty-second stair-climbing tests. The primary outcome measure consisted of an analysis of covariance of the change in scores between the baseline and six-month evaluations.
Results: One hundred and nineteen patients were randomized. The control group consisted of forty patients (thirty-one men and nine women; mean age, 60.9 years); the neoprene-sleeve group, of thirty-eight patients (twenty-seven men and eleven women; mean age, 58.2 years); and the unloader-brace group, of forty-one patients (twenty-eight men and thirteen women; mean age, 59.5 years). Nine patients withdrew from the study. At the six-month follow-up evaluation, there was a significant improvement in the disease-specific quality of life (p = 0.001) and in function (p  0.001) in both the neoprene-sleeve group and the unloader-brace group compared with the control group. There was a significant difference between the unloader-brace group and the neoprene-sleeve group with regard to pain after both the six-minute walking test (p = 0.021) and the thirty-second stair-climbing test (p = 0.016). There was a strong trend toward a significant difference between the unloader-brace group and the neoprene-sleeve group with regard to the change in the WOMAC aggregate (p = 0.062) and WOMAC physical function scores (p = 0.081).
Conclusions: The results indicate that patients who have varus gonarthrosis may benefit significantly from use of a knee brace in addition to standard medical treatment. The unloader brace was, on the average, more effective than the neoprene sleeve. The ideal candidates for each of these bracing options remain to be identified.
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Introduction
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Osteoarthritis is the most common disorder affecting synovial joints, with structural changes of osteoarthritis present in approximately half of the adult population1,13,23,30. The knee is the most commonly affected weight-bearing joint30,47, and varus deformity is the most common malalignment of the knee associated with osteoarthritis.
Nonoperative measures that have been shown to be effective for the treatment of osteoarthritis of the knee include education31, telephone contact46, weight loss15, a walking program25,37, a muscle-strengthening program16,17, and analgesics to control pain1,11,12,23. Intra-articular injections of hyaluronic acid, orgotein, and glucocorticosteroids seem to provide short-term relief, but they must be repeated frequently19,28,32.
Two devices that have been evaluated for the treatment of varus gonarthrosis are wedged insoles40,48 and braces21. Two main types of braces, sleeves and unloading braces, are available; each is used in an attempt to decrease loads through the tibiofemoral joint. Although no controlled trials of use of a simple sleeve for patients who have osteoarthritis of the knee have been reported, to our knowledge, good results have been described anecdotally4,18. As the sleeve provides little mechanical support to the knee, it is thought that the feelings of improved stability and reduced pain are largely due to an improvement in joint proprioception.
Lindenfeld et al. evaluated the effects of the unloader brace on the gait of patients who had varus gonarthrosis and found that the adduction moment at the knee was altered when the brace was worn29. This alteration may decrease the load transmitted through the medial compartment, resulting in less pain. Hewett et al. reported that, although use of the unloader brace did not change the adduction moment in their small sample of patients, there was a significant (p = 0.001) decrease in pain and patients were able to more than double their walking time after nine weeks of wearing the brace20. Matsuno et al. reported on twenty patients who had moderate-to-severe varus gonarthrosis and had worn the unloader brace for one year36. The knee-function score for walking improved significantly and, interestingly, there also was a significant increase in the strength of the quadriceps muscle (p < 0.05 for both).
To our knowledge, only one randomized trial of the effectiveness of the unloader brace for the treatment of varus gonarthrosis has been reported21. In that study, Horlick and Loomer used a double crossover design to randomize forty patients to one of four treatment sequences: use of the brace with the knee in neutral followed by use of the brace with the knee in valgus followed by no use of the brace, use of the brace with the knee in neutral followed by no use of the brace followed by use of the brace with the knee in valgus, use of the brace with the knee in valgus followed by no use of the brace followed by use of the brace with the knee in neutral, or use of the brace with the knee in valgus followed by use of the brace with the knee in neutral followed by no use of the brace. After four six-week periods of follow-up, Horlick and Loomer found that use of the brace with the knee in valgus provided modest relief of pain in relatively young patients who had osteoarthritis of the medial compartment. With the numbers available for study, those authors could not detect a significant improvement in function.
The objective of the current study was to compare an unloader brace, a neoprene sleeve, and medical treatment only (control group) with regard to their ability to improve the disease-specific quality of life and the functional status of patients who had varus gonarthrosis.
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Materials and Methods
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Design of the Study
This prospective, parallel-group, randomized clinical trial was carried out at a single university center. The same research assistant (S. W.-B.) assessed all of the subjects.
Subjects
Eligible subjects were recruited from a consecutive sample of patients with varus gonarthrosis who were seen by orthopaedic surgeons at our outpatient orthopaedic clinic or from a group of people who had answered our advertisements in the local newspaper. We included in the study skeletally mature patients of either gender who lived within a two-hour drive of the treatment center and had osteoarthritis of the knee, pain localized primarily to the medial compartment, and mechanical alignment in more than 0 degrees of varus. A patient was considered to have osteoarthritis on the basis of the criteria of Altman et al.2, which included an age of more than eighteen years, pain in the knee, osteophytes seen on radiographs, and at least one of the following: an age of more than fifty years, morning stiffness of more than thirty minutes' duration, or crepitus in association with active motion of the knee, such as weight-bearing or squatting. The criteria for exclusion from our study were arthritides other than osteoarthritis; an operation on the knee within the previous six months; symptomatic disease of the hip, ankle, or foot; a previous fracture of the tibia or femur; morbid obesity (a body-mass index of more than thirty-five kilograms per square meter); skin disease; peripheral vascular disease or varicose veins that would preclude use of a brace; a severe cardiovascular deficit; blindness; poor English-language skills; and an inability to apply a brace because of physical limitations such as arthritis in the hand or an inability to bend over.
Sample Size
The sample size for the study was calculated with use of the standard deviation of the change score (the difference between the baseline score and the score measured at various intervals after treatment) for the pain domain (91.06 millimeters) of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), derived from a sample of patients who had osteoarthritis of the knee10. Using an alpha of 0.05 and a beta of 0.80, we calculated that it was necessary to have thirty-seven subjects in each group in order to demonstrate a clinically important difference of sixty millimeters between the groups on the pain subscale (zero to 500 millimeters)10. An additional eight patients were added to accommodate anticipated withdrawals from the study. Therefore, 119 patients were required for this study.
Randomization
After informed consent had been obtained from all subjects, treatment was assigned according to a computer-generated blocked randomization scheme with use of sealed envelopes. The patients were stratified on the basis of age (less than fifty years or at least fifty years), deformity (the mechanical axis in less than 5 degrees of varus or in at least 5 degrees of varus), and the status of the anterior cruciate ligament (torn or intact). The patients were randomly assigned to one of three treatment groups: medical treatment only (control group), medical treatment and use of a neoprene sleeve, or medical treatment and use of an unloader brace.
Treatment Groups
Control Group
The treatment that was provided to this group represents the standard medical management of patients who have osteoarthritis of the knee. These patients were given an educational pamphlet on osteoarthritis, which described the pathological characteristics of the disease, how the diagnosis is determined, methods of coping, and the medical treatments available; instructions to use plain acetaminophen on an as-needed basis for relief of pain; and instructions on a home program to maintain flexibility. The regimen did not include formal physiotherapy.
Patients who were taking nonsteroidal anti-inflammatory drugs at the time of presentation were asked to continue taking these medications as they had previously. All patients were asked to keep a diary about any medication that they used during the course of the trial.
Neoprene-Sleeve Group
The patients in this group had the same medical treatment as the control group, but they also were fitted with a neoprene sleeve. They were instructed on the appropriate application and maintenance of the sleeve and were directed to wear it while they were awake for activities that had been troublesome to them in the past. They also were asked to keep a diary about their use of the sleeve.
Unloader-Brace Group
The patients in this group had the same medical treatment as the control group, but they also were fitted with a Generation II valgus-producing functional knee (unloader) brace (Generation II Orthotics, Richmond, British Columbia, Canada). The brace is custom-made and consists of a polyethylene thigh shell connected to a polyethylene calf shell through a polyaxial hinge on the medial side. The hinge was altered with use of a calibrated apparatus to allow application of a 4-degree increase in valgus in the anteroposterior plane. The patients were instructed to wear the brace while they were awake for activities that had been troublesome to them in the past and to keep a diary about their use of the brace.
Outcome Measures
Two disease-specific, health-related, quality-of-life measures and two functional scores were used at the baseline and all follow-up evaluations.
The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) is a multidimensional, self-administered health-status instrument for patients who have osteoarthritis of the hip or knee. It has been validated in randomized clinical trials of nonsteroidal anti-inflammatory drugs7,8,10 and also has been shown to be the most responsive tool in trials of orthopaedic operations for the treatment of osteoarthritis of the hip and knee8,26,27. The WOMAC has three domains: pain (five items), stiffness (two items), and physical function (seventeen items). The score can be reported as the sum of the scores for each domain or as an aggregate score.
The McMaster-Toronto Arthritis Patient Preference Disability Questionnaire (MACTAR) is a so-called priority function questionnaire designed to ensure that the outcomes being assessed are those most important to the subject45. Initially, the subject identifies the three most important activities that are adversely affected by osteoarthritis. The subject then quantifies the degree of trouble or distress pertaining to each activity with use of a visual-analog scale. The MACTAR score is generated from the sum of these three scores on the visual-analog scale.
The functional assessment included the six-minute walking test and the thirty-second stair-climbing test. The six-minute walking test is performed to ascertain the maximum distance that the subject can walk in the allotted six minutes. The subject walks thirty meters in shuttle fashion for the period of the test. Standard prompts are given at specific time-points during the walk. Walking aids are permitted. In addition, pain is evaluated on a visual-analog scale at the end of the test. The thirty-second stair-climbing test is used to measure the number of stairs that the subject can climb in a thirty-second period. One flight (twelve risers) is climbed repeatedly, shuttle fashion, in a stairwell. The subject is allowed to use the handrail or a cane, or both, for the duration of the test. Again, pain is evaluated on a visual-analog scale at the end of the test.
Whether the treatment was a clinical success or a clinical failure was determined for each subject. Since pain with walking is the most common symptom of osteoarthritis6,9, we defined success as a change score (the six-month value minus the baseline value) of one centimeter on a ten-centimeter visual-analog scale for the measurement of pain after the six-minute walking test.
The primary outcome was the six-month change in the subjects' WOMAC aggregate scores.
Confounding Measures
The age, gender, degree of varus deformity, status of the anterior cruciate ligament, and grade of osteoarthritis in the involved knee were noted.
The severity of the osteoarthritis was assessed, with use of the grading system of Kellgren and Lawrence (Table I)24, on anteroposterior and lateral radiographs made with the patient standing. Each radiograph was evaluated by two orthopaedic surgeons in a blinded fashion. Whenever the observers differed with regard to their evaluation of a radiograph, they reviewed it again together without knowing their previous scores for that radiograph. They then reached an agreement on the score, which, in all instances, was one of the scores from the previous evaluation.
The angular deformity (mechanical axis) was measured on single-limb-stance hip-to-ankle radiographs with use of the method described by Dugdale et al.14, in which the angle between the weight-bearing line (drawn from the center of the femoral head to the center of the tibiotalar joint) and a line drawn from the center of the knee to the center of the ankle is calculated.
The status of the anterior cruciate ligament (intact or torn) was determined on the basis of the medical history and the physical examination (a difference between sides of one grade on the Lachman test and a positive pivot-shift sign) or the operative notes, if applicable. Because of the severity of the osteoarthritis, it was not always possible to determine accurately if there had been a remote injury of the anterior cruciate ligament.
Protocol
Eligible subjects had a standard physical examination and completed baseline evaluations (the WOMAC, the MACTAR, and six-minute walking and thirty-second stair-climbing tests). Hip-to-ankle radiographs were made, and the angular deformity was measured. The subjects were stratified on the basis of age, the angle of deformity, and the status of the anterior cruciate ligament and then were randomized to one of the three treatment groups.
All patients were given the information pamphlet on osteoarthritis and were instructed on the use of nonsteroidal anti-inflammatory drugs, acetaminophen, and the flexibility regimen. When the unloader brace was to be used, a plaster cast of the involved knee was made and sent to the manufacturer.
Two weeks after the baseline evaluation, the patients returned to have the neoprene sleeve or the unloader brace fitted. The patients in the control group returned as well. This visit was considered to be the starting date of treatment for all three groups.
Follow-up assessments were performed at six weeks, three months, and six months after the starting date of treatment.
Analysis
The primary outcome measure was an analysis of covariance of the change in the WOMAC score at the six-month assessment. Analysis of covariance is performed to determine if there is a significant difference in group variance without identifying the causal group. Simple contrast measures (meaningfully planned comparisons involving pairs of measurements that are used to identify the differences between the treatment groups) were performed to determine significant differences among the means for the three treatment groups. The same analysis was used to compare the change scores for the MACTAR, the six-minute walking test, and the thirty-second stair-climbing test at the six-month assessment. In order to avoid a multiple-comparison bias and to conserve power for the primary outcome, the data for the six-week and three-month periods were evaluated in a descriptive fashion only.
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Results
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Originally, 119 patients were randomized. The control group consisted of forty patients (thirty-one men and nine women; mean age, 60.9 years); the neoprene-sleeve group, of thirty-eight patients (twenty-seven men and eleven women; mean age, 58.2 years); and the unloader-brace group, of forty-one patients (twenty-eight men and thirteen women; mean age, 59.5 years). Nine patients (seven from the control group and two from the neoprene-sleeve group) withdrew from the study. The reasons for withdrawal were dissatisfaction with the group to which they had been randomized (five patients), an inability to attend appointments (two patients), ill health (one patient), and a change in a scheduled date for an operation (one patient).
Thus, the results were evaluated for thirty-three patients in the control group, thirty-six in the neoprene-sleeve group, and forty-one in the unloader-brace group. There were no significant differences with regard to the baseline characteristics among the three groups (Table II).
WOMAC Scores
At the six-month assessment, there was a significant difference among the treatment groups with regard to the mean aggregate change score (p = 0.001), which was -27.9 millimeters for the control group, 97.6 millimeters for the neoprene-sleeve group, and 229.1 millimeters for the unloader-brace group (total worst change score possible, -2400 millimeters). There also was a significant difference with regard to each of the domain change scores. The mean change score for pain (total worst change score possible, -500 millimeters) was -13.1 millimeters for the control group, 13.1 millimeters for the neoprene-sleeve group, and 43.2 millimeters for the unloader-brace group (p = 0.001). The mean change score for stiffness (total worst change score possible, -200 millimeters) was -8.1 millimeters for the control group, 15.5 millimeters for the neoprene-sleeve group, and 28.6 millimeters for the unloader-brace group (p = 0.001). The mean change score for physical function (total worst change score possible, -1700 millimeters) was -6.5 millimeters for the control group, 68.9 millimeters for the neoprene-sleeve group, and 157.2 millimeters for the unloader-brace group (p = 0.004).
Contrast measures of the aggregate score showed a significant difference between the unloader-brace group and the control group (p < 0.001) and a strong trend toward a significant difference between the unloader-brace group and the neoprene-sleeve group (p = 0.062) and between the neoprene-sleeve group and the control group (p = 0.066) (Fig. 1).
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Fig. 1 Graph showing the mean aggregate absolute scores on the WOMAC (Western Ontario and McMaster University Osteoarthritis Index). (The worst score possible is 2400 millimeters.)
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Contrast measures applied to the WOMAC pain domain showed a significant difference between the unloader-brace group and the control group (p < 0.001), a significant difference between the unloader-brace group and the neoprene-sleeve group (p = 0.045), and a trend toward a significant difference between the neoprene-sleeve group and the control group (p = 0.080) (Fig. 2).
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Fig. 2 Graph showing the mean absolute scores of the pain domain of the WOMAC (Western Ontario and McMaster University Osteoarthritis Index). (The worst score possible is 500 millimeters.)
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Contrast measures applied to the WOMAC stiffness domain showed a significant difference between the unloader-brace group and the control group (p < 0.001) and between the neoprene-sleeve group and the control group (p = 0.010). With the numbers available for study, a significant difference could not be detected between the unloader-brace group and the neoprene-sleeve group (p = 0.91).
Contrast measures applied to the WOMAC physical function domain showed a significant difference between the unloader-brace group and the control group (p = 0.001) and a trend toward a significant difference between the unloader-brace group and the neoprene-sleeve group (p = 0.081). With the numbers available for study, no significant difference could be detected between the neoprene-sleeve group and the control group (p = 0.112).
MACTAR Scores
Each patient identified, ranked, and scored the three most important activities affected by the osteoarthritis of the knee. The most commonly identified activities included difficulty walking (fifty patients), difficulty with stairs (forty-one), difficulty participating in sports activities (forty-one), and difficulty sleeping (twenty-one).
At the six-month assessment, the treatment groups differed significantly with regard to the change score for the MACTAR (p = 0.05), which was a mean of 6.9 millimeters for the control group, 25.5 millimeters for the neoprene-sleeve group, and 41.6 millimeters for the unloader-brace group (total worst change score possible, -300 millimeters). Contrast measures showed a significant difference between the unloader-brace group and the control group (p = 0.017). With the numbers available, no significant difference could be detected between the unloader-brace group and the neoprene-sleeve group (p = 0.174) or between the neoprene-sleeve group and the control group (p = 0.308) (Fig. 3).
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Fig. 3 Graph showing the mean absolute scores on the MACTAR (McMaster-Toronto Arthritis Patient Preference Disability Questionnaire). (The worst score possible is 300 millimeters.)
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Six-Minute Walking Test
With the numbers available, no significant difference could be detected among the treatment groups with regard to the mean change score for the distance walked at the six-month assessment, which was 25.5 meters for the control group, 8.6 meters for the neoprene-sleeve group, and 29.6 meters for the unloader-brace group (p = 0.480). There was, however, a significant difference among the treatment groups with regard to the change score for pain as determined immediately after the walking test (mean, -2.6 millimeters for the control group, 7.6 millimeters for the neoprene-sleeve group, and 16.3 millimeters for the unloader-brace group; p 0.001). Contrast measures showed a significant difference between the unloader-brace group and the control group (p < 0.001), between the unloader-brace group and the neoprene-sleeve group (p = 0.021), and between the neoprene-sleeve group and the control group (p = 0.037) (Fig. 4).
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Fig. 4 Graph showing the mean absolute scores for pain on the six-minute walking test. (The worst score possible is 100 millimeters.)
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Thirty-Second Stair-Climbing Test
At the six-month assessment, no significant difference could be detected among the treatment groups with regard to the mean change score for the number of stairs climbed, which was -5.18 steps for the control group, 6.44 steps for the neoprene-sleeve group, and 11.03 steps for the unloader-brace group (p = 0.350). There was, however, a significant difference among the treatment groups with regard to the mean change score for pain as determined immediately after the stair-climbing test (-1.09 millimeters for the control group, 8.1 millimeters for the neoprene-sleeve group, and 20.4 millimeters for the unloader-brace group; p < 0.001). Contrast measures showed a significant difference between the unloader-brace group and the control group (p < 0.001), between the unloader-brace group and the neoprene-sleeve group (p = 0.016), and between the neoprene-sleeve group and the control group (p = 0.043) (Fig. 5).
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Fig. 5 Graph showing the mean absolute scores for pain on the thirty-second stair-climbing test. (The worst score possible is 100 millimeters.)
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Descriptive Data
In order to conserve power for the analysis of the six-month change scores, the change scores at the six-week and three-month time-periods were not analyzed statistically. The pattern over time was similar for all outcome measures that were evaluated (Figs. 1, 2, 3, 4, 5). In both the unloader-brace group and the neoprene-sleeve group, there was an initial improvement during the first three weeks and maintenance of this improvement. In contrast, the control group had a gradual worsening of symptoms and function over time.
Clinical Success and Failure
There was a significant relationship between clinical success and the type of treatment (chi square = 13.747, p = 0.001). Six (18 percent) of the thirty-three patients in the control group, sixteen (44 percent) of the thirty-six patients in the neoprene-sleeve group, and twenty-five (61 percent) of the forty-one patients in the unloader-brace group were considered to have been managed successfully according to our definition.
We examined the relationship between clinical success and the baseline variables for the unloader-brace group only. This study was not designed specifically for these analyses because of insufficient power; therefore, the data should be interpreted cautiously and should be used to generate hypotheses for additional studies (Table III). The baseline values for the WOMAC aggregate score (p = 0.024) and for pain after the six-minute walking test (p = 0.002) were significantly greater (indicating that the patients were more symptomatic) for the patients who were considered to have had a successful clinical outcome compared with those who were considered to have had a failure of treatment. With the numbers available for study, we could not detect a significant relationship between clinical success and age, gender, the severity of the osteoarthritis, the degree of the varus deformity, or the status of the anterior cruciate ligament.
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TABLE III
RELATIONSHIP BETWEEN BASELINE DEMOGRAPHIC VARIABLES AND CLINICAL SUCCESS AND FAILURE IN THE UNLOADER-BRACE GROUP
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Discussion
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The previous work of Horlick and Loomer21 provided the impetus for the current study. Those authors found some decrease in pain but no improvement in function with use of the unloader brace. However, they used a crossover design (a research method whereby the same patient receives both types of treatment, one after the other, with the order being decided randomly44), which is not ideal when blinding is unattainable. In addition, there is an unknown carryover effect (the ongoing effect of a treatment after it has been discontinued) of bracing whereby the effect of the treatment that is given first still may be present well into the period of the second treatment. We believe that a parallel-group randomized clinical trial may be a better design.
We chose to have three treatment groups (control, neoprene sleeve, and unloader brace) for two reasons. First, we are not aware of any previous controlled trial of use of a sleeve only for patients who have osteoarthritis of the knee and we wanted to determine the effectiveness of this treatment. Second, if the current study demonstrated that use of a custom-made unloader brace was effective then we wanted to determine whether this was primarily due to the brace's effect on proprioception (in which case the level of effectiveness would be comparable with that of the sleeve) or whether it was due to proprioception combined with a biomechanical unloading effect (in which case the brace would be more effective than the sleeve). In order to minimize expectation bias, the subjects were unaware of the proposed mechanism of the two bracing options. They were simply informed that it was not known if bracing was useful at all in the treatment of osteoarthritis and that the purpose of the study was to evaluate the effectiveness of two types of braces compared with that of the best available medical treatment.
We included two functional tests in the battery of outcome measures. The timed walking test is commonly used in studies evaluating treatment for osteoarthritis of the knee, but it is difficult to use this test as a measure of improvement as the score rarely improves markedly even when all other outcomes show an important change5. However, patients who have osteoarthritis of the hip or knee have described walking as the most common cause of pain, and pain with stair-climbing has been the signal measurement chosen most frequently by such patients6,9. The MACTAR data in the current study are in agreement with those reported in the literature; difficulty walking and difficulty with stairs were identified as the activities that most often caused the most distress for our patients. Therefore, we believe that measurements of pain on a visual-analog scale at the end of timed walking and stair-climbing tests are very sensitive indicators of the effectiveness of the brace. In the current study, neither the neoprene sleeve nor the unloader brace had any effect on the distance that the patient was able to walk or the number of stairs that the patient was able to climb, but both had a marked effect on pain during these activities.
Several authors have shown that proprioception is decreased in patients who have osteoarthritis of the knee3,22,34,35,41-43. In addition, it has been demonstrated that use of an elastic bandage or a neoprene sleeve markedly improves proprioception in these patients22,33,38. Since a sleeve provides little or no mechanical support to the knee, it is thought that the feelings of improved stability and reduced pain are largely a result of an improvement in joint proprioception. The results of the current study show that a sleeve does, on the average, improve the disease-specific quality of life and reduce the pain associated with activities of daily living as demonstrated by the change scores for pain on the six-minute walking test and the thirty-second stair-climbing test. A sleeve is reasonably comfortable and can be worn for extended periods. Its relatively low cost is attractive to patients who have limited means of paying for a custom-made brace; however, the material loses its elasticity over time, which may result in a loss of effectiveness and necessitate replacement. In addition, some patients cannot tolerate having the neoprene against their skin, especially in hot weather.
The present study clearly showed a decrease in pain and an improvement in the disease-specific quality of life for most of the patients who were managed with the unloader brace. It is not yet clear how the unloader brace produces its effect. Hewett et al. did not find a change in the adduction moment in patients who were wearing an unloader brace20; however, Lindenfeld et al. found a significant difference (p = 0.007) in the adduction moment, which was correlated (r = 0.73) with an improved clinical outcome29. Similarly, Pollo et al. found a decrease in adduction moment in their small group of nine subjects39. It is likely that this brace combines some degree of compartment unloading with an improvement in proprioception. This hypothesis is supported by the findings of Matsuno et al., who noted an improvement in the postural sway of patients who were wearing an unloader brace36. A stabilometer, developed to assess the equilibrium function of the limb, objectively recorded the instability of the center of gravity with the patient standing upright. A significant change in the mean lateral movement (17.5 centimeters before application of the brace compared with 15.7 centimeters afterward; p < 0.05) revealed that the total movement of the center of gravity decreased. Matsuno et al. concluded that this was a result of an improvement in the lateral stability of the knee.
It should be noted that, although the patients in the current study found the unloader brace to be reasonably comfortable, it was more common for them to wear the brace for specific activities rather than for the entire day. This may limit the usefulness of the brace for people who work; however, it is not yet known which patients are ideal candidates for such a brace, and additional studies are required to identify important predictive variables.
The two types of braces used in this study seemed to decrease pain and to improve function for patients who had varus gonarthrosis. The neoprene sleeve, which probably elicits its effect through an improvement in joint-position sense, conferred a modest decrease in symptoms and could be used by any patient who has osteoarthritis of the knee regardless of the degree of deformity. The valgus-producing functional knee (unloader) brace, which probably elicits its effect through a combined improvement in joint-position sense and a decrease in compartment loading, was, on the average, more effective than the simple sleeve.
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Footnotes
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*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Funds were received in total or partial support of the research or clinical study presented in this article. The funding source was Generation II Orthotics Incorporated, Richmond, British Columbia, Canada.
Fowler Kennedy Sport Medicine Clinic, 3M Centre, University of Western Ontario, London, Ontario N6A 3K7, Canada.
Department of Orthopaedic Surgery, London Health Sciences Centre, University Campus, 339 Windermere Road, London, Ontario N6A 5A5, Canada.
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Abstract
Introduction