By ANNE QUISMORIO, MD, MPH
SHUNTARO SHINADA, MD
RICHARD S. PANUSH, MD | October 9, 2011
http://www.musculoskeletalnetwork.com/display/article/1145622/1963047



 The Journal of Musculoskeletal Medicine. Vol. 28 No. 10
PRINCIPLES OF CARE
Goals of therapy include the restoration and preservation of patients' physical independence by providing symptomatic relief and maintaining quality of life and function. The ultimate goals are to halt disease progression (have “disease-modifying” therapy for OA), reverse established disease, achieve “cures,” and prevent disease. However, the current therapies, although usually helpful, are only palliative. Thus, the basic principles for managing OA pain (Table 1) are as follows:
 

•  Confirm the diagnosis. Do not miss calcium pyrophosphate dihydrate crystal deposition disease, inflammatory arthritis, erosive/inflammatory OA, polymyalgia rheumatica (PMR), fibromyalgia syndrome (FMS) (alone or superimposed), associated depression, neurological or vascular disease, endocrinological disease (thyroid or parathyroid), chronic pain syndromes (eg, complex regional pain syndrome), tendinitis/bursitis (do not confuse epicondylitis with elbow disease, de Quervain tenosynovitis with wrist arthritis, anserine bursitis with knee arthritis, or trochanteric bursitis with hip disease), ochronosis, or hemochromatosis. When in doubt, obtain expert consultation.

•  Seek preventable or reversible underlying or primary disease.

FIGURE

The basic principles for managing osteoarthritis (OA) pain include identifying the disease site or sites. Disease may be "generalized" but often is localized to specific joints. As in other joints, local heat, physical measures, and topical therapies may be beneficial for knee OA.

•  Identify the site or sites of OA. Disease may be “generalized” but often is localized to specific joints, such as the distal interphalangeal (DIP), first metacarpophalangeal (MCP), first carpometacarpophalangeal (CMC), axial skeleton, hip, knee (Figure), and first metatarsophalangeal (MTP) joints.

•  Use reasonable clinical judgment in assessing patients. Experienced clinicians usually recognize OA readily without obtaining extensive diagnostic studies. Plain x-ray films usually are sufficient to identify anatomical abnormalities. Serological studies usually are not necessary, and they may simply introduce confusion—rheumatoid arthritis, systemic lupus erythematosus, and other rheumatologic disorders may be excluded with a thoughtful, thorough, informed clinical evaluation without laboratory testing.
•  Begin therapy with patient education, explanation, discussion of prognosis, and nonpharmacological modalities. Many patients feel relieved to learn that their disease is not necessarily rapidly progressive or destructive. Patients can benefit from various nonpharmacological strategies.
Because obesity is a risk factor for the development and progression of OA, patients should be counseled on weight loss. Exercise programs should be tailored to individual patients.
Attention to footwear, gait, and ambulation may result in symptomatic improvement. Patients should be educated about the proper use of walking aids because they may help reduce hip and knee OA pain.
Useful adjuncts to management include help with activities of daily living, activity modification, quadriceps strengthening exercises, patellar taping, and formal programs of occupational and physical therapy. Some patients cope better and some symptoms may be minimized with cognitive-behavioral therapy or formal counseling.

•  Pharmacological therapy, if needed, begins with acetaminophen (up to 4 g/d). NSAIDs also are beneficial but should be used at the lowest effective dose. The advantage of acetaminophen over NSAIDs is its safety profile. Because NSAIDs have been associated with GI and renal adverse effects, they should be used with caution in patients who have underlying cardiovascular, renal, or GI disease. The response to a specific NSAID differs from one patient to another.

Cyclooxygenase (COX)-2 inhibitors, such as celecoxib(Drug information on celecoxib), may be preferable for patients who have a history of GI ulcers, are receiving anticoagulation therapy, or have a bleeding diathesis. NSAIDs may be added as clinically indicated for younger patients and perhaps patients who do not have comorbid medical problems, are also taking corticosteroids or anticoagulants, and did not have previous ulcer disease or GI bleeding. To prevent GI adverse effects, a COX-2 selective inhibitor or a nonselective NSAID together with misoprostol(Drug information on misoprostol) or a proton pump inhibitor may be prescribed. We also might prescribe a nonacetylated salicylate (disalicylate, choline magnesium trisalicylate).
For persistently symptomatic joints for which injections are feasible, intra-articular corticosteroids or hyaluronan may be considered. If there is persistent pain, tramadol(Drug information on tramadol) also should be considered. This regimen should provide satisfactory symptomatic relief for most patients with OA. Additional pharmacological treatments include some topical medications (capsaicin cream and diclofenac(Drug information on diclofenac) patch or ointment) that also may be quite useful for specific painful or tender areas.

•  Whenever possible, manage monarticular or oligoarticular disease with topical or local therapies or both, avoiding unnecessary systemic medications

.
•  Other approaches to treatment that have been suggested to provide benefit include acupuncture, pregabalin(Drug information on pregabalin), gabapentin(Drug information on gabapentin), milnacipran, and duloxetine(Drug information on duloxetine). Many clinicians now consider glucosamine and chondroitin to have no important clinical value, but they are generally safe and well-tolerated and some patients do report benefit. In our opinion, there is insufficient evidence to support nonexperimental use of tidal lavage, platelet-rich plasma therapy, or herbal and other complementary and alternative medicines for patients with OA.

•  We do not recommend routine or long-term use of narcotic analgesics for managing

patients with OA. Although these medications are effective for pain management, they should be used rarely and only in patients who are refractory to other pharmacological treatments. Narcotic analgesics should be prescribed by physicians who are experienced in caring for persons receiving these agents.
•  Some surgical procedures for appropriate joints in select patients can result in dramatic benefit.

GENERAL APPROACHES
How to approach patients with "pain all over"?
OA should not cause diffuse, nonlocalized pain; patients who complain of this should be assessed for other or associated conditions. For patients with OA, the symptoms should be correlated with disease in specified joints.
For example, widespread pain may reflect FMS; PMR; other arthopathies or rheumatologic disease; endocrinological or metabolic disorders; neuropathy; vascular disease; central sensitization syndrome; or OA of the shoulders, knees, hips, or axial skeleton, and there also might be bursitis or tendinitis. A careful evaluation can clarify this. When sites with OA are identified and specific symptoms are related to them, rational and individualized therapeutic approaches can be developed that are most likely to be successful, and the ordering of expensive and extensive imaging studies and then prescribing something such as Tylenol #3 can be avoided.
OA can affect multiple joints, especially the DIP joints, proximal interphalangeal (PIP) joints, CMC joints, MTP joints, cervical and lumbar spine facet joints, knees, and hips. Many patients who have OA of the DIP or PIP joints may have physical abnormalities that are asymptomatic. A few patients may have “inflammatory” OA, usually of the hands, with an elevated erythrocyte sedimentation rate or C-reactive protein level. They may benefit from hydroxychloroquine(Drug information on hydroxychloroquine) or NSAIDs.
How to approach patients with localized or oligoarticular OA?
These patients may be treated initially with nonmedicinal approaches, such as physical therapy and local heat therapy. They also may derive benefit from topical therapies, alternatives to oral NSAIDs that include diclofenac gel and diclofenac patch. Lidocaine(Drug information on lidocaine) patches and topical menthol(Drug information on menthol)- and capsaicin-based creams also may provide relief, albeit temporary.

TABLE 2

Approaches to managing OA

Local injection with corticosteroids may be used for patients who have severe pain in 1 or 2 joints. The goal is to provide short-term, temporary relief of OA pain; this usually does not provide long-lasting, permanent relief. Injection of hyaluronic acid into affected joints also may be beneficial for select patients. Patients who do not respond to these may benefit from systemic medical therapies. Acetaminophen may provide symptomatic relief for patients who have OA pain (Table 2).
APPROACHES FOR SPECIFIC JOINTS
Primary OA affects a typical distribution of joints, such as the cervical spine or lumbar spine. OA of other joints should alert the physician to a possible secondary OA.
Hands/wrists. Although PIP and DIP OA can be unsightly, it usually is asymptomatic and may not cause discomfort, pain, or disability. Conservative therapy with local heat or paraffin(Drug information on paraffin) baths or topical therapies may provide pain relief. Local corticosteroid injections can reduce pain but may be difficult without ultrasonographic guidance to ensure proper localization. Seldom would a patient require joint fusion surgery for severe pain at the PIP or DIP joints. Acetaminophen or NSAID therapy or both may also provide temporary relief, especially when the joints are symptomatic.
The first CMC joint may be problematic because it is used in grasping and pinching and for almost every activity that involves the hand. Patients often lose strength in their fingers and may need assistive devices to complete their activities of daily living. A custom splint worn at nighttime can ease the pain. Local corticosteroid injections usually are of limited benefit. The potential for surgical intervention is limited by the need to use this joint in everyday life.
Shoulders. Primary OA of the shoulder does not occur often. Degenerative changes of the glenohumeral joint should prompt the physician to consider that OA may be the result of another cause (eg, trauma, previous infection, neuropathy or radiculopathy, crystal deposition disease). If corticosteroid injections are ineffective or contraindicated, hyaluronic acid injections may be beneficial for glenohumeral joint arthritis. Ultrasonographic guidance is recommended.
Hips. OA of the hip causes pain and disability for many patients. Corticosteroid and hyaluronic acid injections may be of benefit. When conservative, physical, systemic, and injection therapies are ineffective, surgical intervention with total hip arthroplasty should be considered.

Knees. Knee OA is a common problem. As in other joints, local heat, physical measures, and topical therapies may be beneficial.

We recommend quadriceps strengthening and range of motion exercises, although their value has been questioned. Glucosamine may be only slightly beneficial to patients who have mild knee OA. Corticosteroid and hyaluronic acid injections may provide temporary relief for patients who have contraindications to surgical intervention.
Attention to lower extremity biomechanics is important. Some patients are helped by assisted ambulation, orthoses, and braces. Surgery is indicated when pain becomes severe and diminished function and quality of life become unacceptable to the patient. Radiographic changes associated with knee OA usually are not good indicators for the necessity of surgery; however, when these changes are associated with refractory pain disability, surgical intervention should be considered. Total knee arthroplasty usually is preferable to arthroscopic and partial knee arthroplasties for knee OA.

Feet. OA of the feet usually involves the first MTP joint and presents as a bunion or hallux valgus. This condition can be exacerbated in patients who wear narrow or high-heeled shoes. Wide-fitting shoes or orthoses help reduce the valgus deformity, which may reduce pain. Surgery is indicated when recommended therapeutic measures prove to be ineffective.

Neck/back. The principles of care outlined above apply to OA of the axial skeleton. See the “Bibliography” for more information.

SUMMARY
We counsel patients with OA to have reasonable expectations, and we express confidence that we have therapies that will improve their lives. For patients who have one or a few joints involved, we try largely physical, topical, and injection therapies, sparing them systemic medications. For those who are still symptomatic or have multiple-joint involvement, we include systemic therapy. Most patients can be helped. A few may need referral for more expert consultation.

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JRRD
Volume 47, Number 5, 2010
Pages 419–430
Journal of Rehabilitation Research & Development

ANALYSIS OF BIOMECHANICA EFFECTIVENESS OF VALGUS-INDUCING KNEE BRACE FOR OSTEOARTHRITIS OF KNEE
Thomas Schmalz, PhD;
1*Elmar Knopf, MD;
2Heiko Drewitz, CPO;
1Siegmar Blumentritt, PhD
1–2Bock Healthcare, Department of Research, Duderstadt, Germany;
2Orthopaedic Department, Georg August 
University, Göttingen, Germany
Abstract—The biomechanical effectiveness of a valgus-inducing knee brace was investigatedfor 16 patients with knee
osteoarthritis (mean +/– standard deviation age 56 +/– 10 yr,
height 172 +/– 9 cm, mass 83 +/– 7 kg, body mass index 27.6 +/–
4.5 kg/m
2
). At the time of investigation, all subjects had been
wearing the brace for at least 4 weeks. In addition to conduct-ing standard gait analysis, we calculated the valgus moment
generated by the brace by using a novel system that measured
the actual deformation of the brace during stance phase and
determined the reaction force created by the brace on the leg.
The mean maximum value of the orthotic valgus moment was
0.053 Nm/kg, which represents approximately 10% of the
external genu varus moment without the brace. This finding
may explain the pain relief reported by patients using such
braces in clinical studies. Use of the tested brace also
decreased the magnitude of gaitasymmetry between the braced
and contralateral legs during walking (horizontal ground reac-tion force, external knee flexion moment), presumably because
the subjects’ need to walk abnormally to shield the knee from
pain was reduced.
Key words: biomechanics, gait analysis, knee loading, knee
osteoarthritis, orthopedics, orthotics, pain, rehabilitation, val-gus bracing, visualanalog scale.
INTRODUCTION
Osteoarthritis of the knee isone of the most common
joint diseases. The incidence of painful arthritic knees
increases significantly from the third decade onward [1].
Epidemiological studies showthat approximately 5 to
6 percent of the population present clinically with painful
knee osteoarthritis [1]. Treatment may be by operative
and nonoperative methods. In addition to arthroscopy,
operative treatments includejoint replacements and
osteotomies. Nonoperative treatments are usually offered
in mild to moderate cases or when surgery is not feasible,
and may include drug therapies, physiotherapeutic mea-sures, and orthopedic devices (walking aids, orthopedic
inserts, shoe sole elevations, knee braces). According to
the most recent analysis, less than 1 percent of all
patients with knee osteoarthritis are fitted with a knee
brace [2].
The clinical effectiveness of this medical device has
been reported in previous studies (i.a., [3–8]). However,
studies published to date show conflicting results regard-ing the biomechanical mechanism of the knee brace.
Many studies have shown that the external varus
moment is a suitable indicator of knee joint loading,
Abbreviations: BW = body weight, SD = standard deviation,
VAS = visual analog scale, WB= with brace, WOB = without
brace.
*
Address all correspondence toThomas Schmalz, PhD;
Otto Bock HealthCare GmbH, Forschungs-und Entwick-lungswerkstatt, Labor für Biomechanik, Hermann-Rein-Straße 2a, D-37075 Göttingen, 0551 3075131 Germany;
fax: 0049-551-3075134. Email: schmalz@ottobock.de
DOI:10.1682/JRRD.2009.05.0067
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JRRD, Volume 47, Number 5, 2010
which is increased in the majority of cases with varus
deformities secondary to knee osteoarthritis [9–13]. Sci-entific investigations of the effect of a knee brace on the
external varus moment report either a reduced varus
moment [14–16] or no significant change in this biome-chanical parameter [17–19]. These contradictory results
raise questions about whether or not forces produced by
knee braces are sufficient to significantly alter the exter-nal moment.
A number of researchers have suggested that braces
for treating varus knee osteoarthritis generate a valgus
moment, partially compensating for the external varus
moment [15,20] and, therefore,reducing the need for the
muscles and ligaments to counteract the pathological
forces [21]. This mechanism isalso believed to result in
reduced joint force within  the medial compartment,
reducing pain symptoms [20–21].
Given the contradictory theories and findings, ana-lyzing the external varus moment in the gait laboratory
appears to be inadequate to provide evidence about the in
vivo function of a knee osteoarthritis brace. For this rea-son, previous studies have used specially designed test
braces with highly precise integrated sensors to directly
measure the valgus moment created by the brace
[16,20,22].
In contrast, this article introduces a method for deter-mining the valgus moment without an instrumented test
brace. The approach presented here uses each patient’s
individual brace without modification. Using the pre-scribed, fitted brace worn by each person provides more
direct evidence about the actual effect of the brace in
vivo. The overall goal of this study is to add to the body
of knowledge regarding the biomechanical basis for val-gus-inducing knee braces.
METHODS
Patients
Sixteen patients (eight male, eight female) diagnosed
with medial knee osteoarthritis by orthopedists were
recruited for this study (Table 1). The clinical criteria for
Table 1.
Data for participants with knee osteoarthritis wearing valgus-inducing brace.
Patient Sex Age (yr) Height (cm) Mass (kg) BMI
Wearing
Duration
(wk)
Wearing
Time (h/d)
Walking
Distance
(km/d)
1 M 60 148 78 23.1 4 12.0 6.0
2 M 48 160 94 36.5 4 12.0 7.0
3 F 45 157 57 23.0 6 9.0 6.0
4 F 41 178 72 22.7 4 9.0 8.5
5 F 43 169 77 27.1 4 6.0 4.5
6 F 62 158 67 26.8 6 11.0 2.0
7 F 65 172 65 22.1 164 10.0 7.5
8 F 59 167 100 35.8 4 12.0 7.5
9 F 67 171 94 32.0 4 8.0 5.5
10 M 61 170 92 31.8 8 6.0 3.5
11 M 45 171 93 31.7 4 8.0 7.5
12 M 57 173 84 28.2 6 11.0 3.0
13 M 54 180 91 28.0 7 12.0 4.0
14 M 50 192 92 25.0 21 16.0 6.5
15 F 67 176 82 26.6 60 10.0 5.0
16 M 64 179 86 26.8 52 2.0 1.0
Mean — 56 172 83 27.9 22 9.6 5.3
SD — 9 9 12 4.5 42 3.2 2.2
Min — 41 157 57 22.1 4 2.0 1.0
Max — 67 192 100 36.5 164 16.0 8.5
BMI = body mass index, F = female, M = male, Max = maximum, Min = minimum, SD = standard deviation.
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SCHMALZ et al. Biomechanical effectiveness of valgus-inducing knee brace
diagnosis of osteoarthritis included radiological assess-ment combined with patient reports of knee swelling,
morning stiffness, pain duringambulation, or joint stiff-ness. An experienced orthopedist grouped the patients
according to the osteoarthritis classification system
developed by Kellgren and Lawrence [23]. One patient
was assigned to level 1, five patients to level 2, seven
patients to level 3, and three patients to level 4.
All patients had been previously prescribed by their
treating physician the knee brace used in this study for
treatment of their osteoarthritis and had worn it daily for
a minimum of 4 weeks at the time of testing. The 4-week
period was considered sufficient to verify wearing com-pliance and permit adequate acclimation to the brace
(Table 1). Exclusion criteria for the study included recent
injuries, skin disorders, varicosities, and diseases other
than knee osteoarthritis influencing the gait pattern.
All patients signed an informed consent to participate
in this study. Each recruited patient traveled to the gait
laboratory for one measurement session. In addition to
the biomechanical measurements, they were asked to give
a short subjective assessment of the effect of the brace.
Functional Description and Fitting Procedure of
Tested Knee Brace
The patients used the Genu Arthro knee brace, which
has a unilateral sidebar design (Otto Bock; Duderstadt,
Germany [Figure 1]). The Genu Arthro brace is a prefab-ricated system that is individually adjusted to each
patient’s body measurements. All brace fittings were con-ducted by the same qualified and experienced orthotist.
The pain-relieving function of this brace is based on
the classic three-point pressure principle. Thigh and
shank segments are connected by a single axis joint on
the lateral side of the leg. An adjustment mechanism per-mits variable positioning of the thigh segment in the
coronal plane while the patient is standing (Figure 2).
Once the brace has been individually adjusted, reaction
forces will be generated on the thigh depending on the
magnitude of the adjustment.
At the beginning of the treatment phase, the brace
adjustment was optimized for each patient according to
his or her individual needs. The most important criterion
for this procedure was the patient’s tolerance of the val-gus forces resulting from the coronal plane adjustments,
as illustrated in Figure 2. After the patients were
recruited into this study, the individual adjustment of the
valgus force was evaluated and modified as needed
before the measurement session began.
Subjective Assessment
Before the biomechanical investigations, the patients
were queried about their medical history and perceptions
of the quality of brace fitting. Subjects were asked to
assess the fit of the brace, wearing comfort of the compo-nents, appearance, and ease of use on a scale ranging
from 0 (“very poor”) to 6 (“very good”). Patient self-reports of daily wearing time were recorded to assess
compliance in wearing the brace. Pain while walking was
measured with a visual analog scale (VAS) ranging from
0 (“no pain”) to 10 (“worst pain imaginable”).
Figure 1.
Patient wearing Genu Arthro valgus-inducing knee brace used in study.
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Biomechanics
Standard Gait Analysis
Gait analysis was conducted under two conditions:
without brace (WOB) and with brace (WB), in random
order. For the WB condition, an additional static mea-surement was recorded without the thigh portion of the
brace secured to the leg. Eight to ten walking trials were
recorded for each condition.
Measurement of ground reaction forces during walk-ing was conducted bilaterally with use of two force plates
(measuring frequency 1,080 Hz; Kistler; Winterthur,
Switzerland). Motion kinematics were tracked by an
optoelectronic six-camera system (120 Hz; Vicon;
Oxford, United Kingdom) with use of passive reflective
markers fixed to anatomical reference points. The marker
set used comprises seven markers for each side of the
body (acromioclavicular joint, lateral epicondyle of
elbow, wrist, greater trochanter, lateral femoral condyle,
lateral malleolus, and fifth metatarsal head). External
moments acting on the major joints of the lower limb
were calculated based on kinematic data and ground reac-tion forces with use of Vicon Body Builder 3.5 software.
Determination of Valgus Moment Produced by Brace
The moment created by the brace can be determined
from the reaction force acting on the proximal force
application point of the brace and from the effective lever
arm. The effective lever arm results from the functional
length of the thigh module (Figure 3(a)).
The first step was to determine the relationship
between the reaction force of the brace Fbr
and the result-ing frontal deformation of the brace by means of a simple,
self-developed force-measuring station (Figure 3(a)).
With this station, the force acting at the proximal edge of
the thigh piece (Pin Figure 3(a) and (c)) is transferred
directly by a cord and pulley assembly so it can be mea-sured by a spring dynamometer (SDM, Hahn-Kolb; Stutt-gart, Germany).
Before gait analysis, the displacements Xi
of the
point Presulting from the acting forces were determined
by means of a simple linear scale (Figure 3(c)). After
recording a set of 15 to18 pairs of values for Fbr
and Xi
for each brace, we found the following linear relationship
(Figure 3(b)–(c)):
where X0
= initial position in unloaded condition, Xi=
change in distance compared to unloaded condition, Fbr=
reaction force, and Cbr
= stiffness of brace, i= 1 . . . (15
. . . 18).
Based on this correlation, the stiffness of each individu-ally adjusted brace Cbr
could be defined by means of a
regression calculation (example is shown in Figure 3(b)).
Once the individual value for Cbr
has been deter-mined, the valgus moment of the brace can be determined
from gait laboratory data. Measuring the specific defor-mation of each brace during the WB gait analysis enabled
calculation of the biomechanical effect of the device in
the frontal plane.
Three additional markers wereattached to the brace
for this purpose (uniaxial hinge, proximal, and distal end
of the brace). Based on the three-dimensional coordinates
of these markers, deformation (relative to the static mea-surement taken before the thigh segment was cinched
down) was determined with use of simple trigonometric
calculations. This deformation,combined with the stiffness
COrthpermits calculation of the reaction force and associ-ated moment created by the brace. The brace valgus
moment was calculated during the first 50 percent of the
gait cycle, when knee joint loading is of particular interest.
Figure 2.
Different basic adjustments to Genu Arthro brace. Left: low
deformation = low valgus moment after cinching up thigh section;
right: strong deformation = high valgus moment after cinching up
thigh section.
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SCHMALZ et al. Biomechanical effectiveness of valgus-inducing knee brace
Data Processing
Mean values standardizedto the gait cycle were
derived for all biomechanical parameters for each subject.
Mean group values were then calculated, permitting
Figure 3.
(a) Force measuring station for defining stiffness of brace, (b) individual example demonstrating relation between reaction force of brace leading
to deformation according to equation in main text, and (c) demonstration of measurement principle. Fbr
= force on brace, P= proximal force
application point, SDM = spring dynamometer.
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JRRD, Volume 47, Number 5, 2010
comparison between both conditions and between the
arthritic and contralateral limbs. Significant differences
between the peak values of key biomechanical parame-ters were determined by the Wilcoxon test.
RESULTS
Subjective Assessment
On the basis of the mean ± standard deviation (SD)
8.9 ± 3.4 h/d duration of use reported, we consider these
subjects highly compliant in wearing the brace. The mean ±
SD pain-with-walking VAS score of 6.4 ± 1.7 for the
WOB condition was significantlyreduced to 3.3 ± 1.9 for
the WB condition (p 0.01). Subjective evaluations of
the knee brace—with the exception of wearing comfort at
the thigh—were very favorable, with average scores
ranging between 4.3 (“good”) and 4.9 (“very good”). The
average value of 3.4 for wearing comfort at the thigh may
have resulted from the intermittent feeling of slipping of
the brace reported by six subjects.
Biomechanics
Time-Distance Parameters
The mean walking speed significantly increased from
1.27 m/s WOB to 1.36 m/s WB (p 0.01). Cadence WB
increased significantly compared with WOB, from 107 to
110 steps/min (p 0.01). The step length for the arthritic
limb increased from 0.71 m WOB to 0.73 m WB, while
step length of the contralateral limb reduced from 0.75 to
0.73 m (Table 2).
Ground Reaction Force
The analysis of the vertical component of the ground
reaction force (Figure 4(a)) shows that vertical loading
decreases between 5 and 15 percent of the gait cycle on
the arthritic limb WOB when compared with the con-tralateral leg or with the WB condition. The first vertical
force maximum is also significantly decreased in the
WOB condition compared with the WB condition (104%
vs 109% body weight [BW], respectively, p 0.05).
Significant differences were also observed in the hor-izontal component of the ground reaction force during
early stance phase, sometimes referred to as the “braking
force” (Figure 4(b)). Compared with the contralateral
limb, the horizontal force was significantly reduced
WOB (14.3% vs 17.9% BW, respectively, p 0.01). In
the WB condition, the horizontalforce on the leg affected
by osteoarthritis increased by 16.4 percent BW, which is
comparable to the horizontalforce on the contralateral
limb. No systematic differencescould be identified in the
mediolateral forces under any of the investigated condi-tions (Figure 4(c)).
Biomechanical Characteristics of Knee Joint
The knee flexion moments inthe sagittal plane dur-ing the first part of stance phase are strikingly different
between conditions. The mean maximum flexion moment
for the contralateral knee was 0.45 Nm/kg under condi-tions, while the mean maximum flexion moment for
the arthritic knee WOB was significantly diminished to
0.23 Nm/kg (p 0.01). The maximum flexion moment for
the arthritic knee WB increased to 0.33 Nm/kg, although
this change was not statistically significant. (Figure 5(b)).
The limb loading characteristics of the affected limb
are associated with reduced motion of the knee joint
throughout the stance phase.Both stance phase flexion
and stance phase extension on the affected limb were
both reduced by approximately 3° compared with the
contralateral side (Figure 5(a)). This finding was true
whether or not the brace was being worn.
The mean maximum value of the external varus
moment (0.53 Nm/kg) was the same regardless of the
test condition for the contralateral limb. The mean maxi-mum loading on the arthritic knee WOB increased to
0.63 Nm/kg, although this change was not statistically
Table 2.
Mean time-distance parameters for participants with knee osteoarthritis walking with brace (WB) and without brace (WOB).
Condition Walking Speed (m/s) Cadence (steps/min)
Step Length (m)
Osteoarthritic Limb Nonosteoarthritic Limb
WOB 1.27 107 0.71 0.75
WB 1.36
*
110
*
0.73
†
0.73
†
*
Significant difference between conditions, p 0.01.
†
No significant difference between conditions.
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SCHMALZ et al. Biomechanical effectiveness of valgus-inducing knee brace
significant (Figure 5(c)). Averaged values from gait analy-sis WB did not demonstrate any measurable changes for
this parameter, similar to several prior studies.
Effect on Knee Joint of Moments Created by Brace
The mean curve presented in Figure 6illustrates the
moment created by the braces during the first half of the
gait cycle. The SD reflects important differences between
individual results. The time during stance phase when
maximum loading occurs alsovaried between subjects.
Figure 4.
Mean ground reaction force (F): (a)vertical component (z), (b)horizontal
component (x), and (c)mediolateral component (y). Gray = nonar-thritic contralateral limb (without brace [WOB]), thick black =
arthritic limb with brace, and thin black = arthritic limb WOB. BW =
body weight, t (%GC) = time (% gait cycle).
Figure 5.
Mean biomechanical knee parameters: (a)flexion-extension (Flex-Ext) angle, (b)stance phase external sagittal knee moment (My
), and
(c)stance phase external varus knee moment (Mx
). Gray = nonarthritic
contralateral limb (without brace [WOB]), thick black = arthritic limb
with brace, and thin black = arthritic limb WOB. t (%GC) = time (%
gait cycle).
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JRRD, Volume 47, Number 5, 2010
Overall, the valgus moment generated by the brace
increased during stance phase but only moderately so.
The increase was most obvious between 0 and 10 percent
of the gait cycle, decreasingbetween 10 and 30 percent
of the gait cycle, i.e., during stance phase knee flexion.
Between 30 and 50 percent of the gait cycle, the valgus
effect of the brace increased once again.
Maximum and mean values of the orthotic moment
during stance phase were used as quantitative evaluation
parameters (Table 3). The mean maximum value of
0.053 Nm/kg and the mean value of 0.040 Nm/kg pro-vided by the brace represent 9 and 10 percent, respec-tively, of the external knee moment. Minimum and
maximum percentages fell between 2 and 28 percent for
both parameters, indicating thatthe actual forces applied
to the patient’s leg were quite variable.
DISCUSSION
Measurement of the external genu varus moment of
patients with medial knee osteoarthritis—the standard
parameter for assessing knee loading—very often dem-onstrates an abnormal increase in the varus loading, even
without associated changes in the knee axis [10,13,18]. In
theory, this parameter could be useful for estimating the
prognosis for osteoarthritis inthe future and monitoring
the effectiveness of various treatment methods. The
results in this study correspond to those of earlier studies
that did not show any significant influence on the exter-nal varus moment created by the knee braces [17–19],
supporting the conclusion that the effect of the brace in
the real world is insufficientto significantly reduce this
moment. We believe that the main effect of an unloader
brace, in most cases, is compensation for a portion of the
external load. The consequences of such an effect are
decreased internal moments (those created by the mus-cles and ligaments) resulting indecreased forces on the
medial portion of the knee joint.
Contradictory results from other studies [14–16] may
be an artifact of different investigation approaches (e.g.,
use of instrumented braces, unrealistically tight adjust-ments of the braces). Results from previous studies on
the effect of braces on knee axis movements are also
equivocal. While several studies report positive results
[24–25], Hamann’s study investigating 20 knee osteoar-thritis patients found no relationship between X-ray find-ings and mode of action of the tested knee braces [18].
In our study, the valgus moments created by the
braces were measured for the first time while in use by
the patients. The mean value of 0.040 Nm/kg and the
mean maximum value of 0.053 Nm/kg for this cohort
correlate well with prior studies using different instru-mented braces. Self et al. indicated values of 0.038 and
0.050 Nm/kg [16], the values reported by Pollo et al.
were 0.071 and 0.133 Nm/kg [20], and the latest study
conducted by Fantini Pagani et al. identified values of
0.030 and 0.102 Nm/kg [22]. These absolute values sug-gest that the moment created by the brace varies, with
Self at al. between 7 and 12percent of the external
moment, Pollo et al. between 6 and 20 percent, and Fan-tini Pagani et al. between 7 and 20 percent. These results
Figure 6.
Mean valgus moment of brace (Mbr
) for first 50 percent of gait cycle.
Thick black = mean, thin black = mean ± 1 standard deviation.
t (%GC) = time (% gait cycle).
Table 3.
Moment generated by knee brace (Mbr
) and percentage of external genu varus moment (Mx
).
Evaluation Parameter
Mbr
(N·m/kg) Mbr
(% Mx
)
Mean Min Max Mean Min Max
Max 0.053 0.009 0.121 9 2 28
Mean (10%–50% GC) 0.040 0.001 0.111 10 2 28
GC = gait cycle, Max = maximum, Min = minimum.
427
SCHMALZ et al. Biomechanical effectiveness of valgus-inducing knee brace
compare favorably with the value of 10 percent found in
this study. Larger effects with the brace calculated in
some studies may reflect orthoses tightened so snugly
that they would not be well tolerated by the patients in
real world use.
We therefore suggest that inrealistic situations, the
valgus moment produced by the brace during walking
may compensate on average for approximately 10 per-cent of the external varus moment at the knee despite
considerable deviations from this mean value in individu-al cases. Biomechanical-model calculations suggest that
a moment from the brace of this magnitude would result
in a reduction of joint forceswithin the medial compart-ment on the order of 80 to 100 N [20]. A reduction in
internal knee forces of this magnitude supports the
hypothesis that the pain relief and functional improve-ments reported by osteoarthritis patients may be the
result of the reduction in internal joint loading that the
brace provides.
Alterations in the gait pattern between the WOB and
WB conditions can be influenced by changes in walking
speed. The increase in the vertical ground reaction force
for the affected limb WB could be due to the observed
mean difference of 0.09 m/s in walking speed [26]. This
relatively small change in velocity did not result in sig-nificant differences in most kinetic and kinematic gait
parameters as compared with the unaffected limb. Other
differences between the WB and WOB conditions for the
affected limb, such as the horizontal ground reaction
force and external flexion moment in the first 30 percent
of the gait cycle, cannot be attributed to a walking speed
difference of 0.09 m/s [27]. Therefore, walking without
the brace can be characterized by reduced walking speed
accompanied by significant step-length asymmetry,
reduced brake force of the arthritic limb immediately
after weight acceptance, and reduced sagittal loading
throughout stance phase. These findings correlate well
with the results of an earlier extensive study reporting on
the gait pattern of 139 knee osteoarthritis patients [28].
Gait pattern changes of this sort appear to be a protective
mechanism to reduce joint pain, as illustrated by the
reduction in external flexion moment, which correlates
directly with a reduction in joint contact forces [28]. The
present study shows that a brace can also contribute to a
more symmetrical gait pattern if deviations from normal
in the arthritic limb can besignificantly reduced. Objec-tive measurements of this reduction in asymmetry may
correlate with the pain-reducing effect of these medical
devices.
CONCLUSIONS
The results from this study show that the studied val-gus-inducing knee brace can compensate for approxi-mately 10 percent of the external genu varus moment.
This compensation appears to be the main biomechanical
mechanism that results in a reduction of joint force
within the medial joint compartment. This biomechanical
effect is an essential requirement for the reduced pain and
improved overall function (such as a more symmetrical
gait pattern) that result from the use of such braces.
Orthotic treatment can effectively manage patients at
early and middle stages of osteoarthritis or when other
treatment methods are not applicable.
ACKNOWLEDGMENTS
Author Contributions:
Study concept and design:S. Blumentritt, T. Schmalz, E. Knopf.
Acquisition of data:T. Schmalz, E. Knopf.
Analysis and interpretation of data:T. Schmalz, E. Knopf.
Drafting of manuscript:T. Schmalz.
Critical revision of manuscript for important intellectual content: 
T. Schmalz, S. Blumentritt.
Statistical analysis:E. Knopf, T. Schmalz.
Administrative, technical, or material support:H. Drewitz.
Study supervision:S. Blumentritt, T. Schmalz.
Financial Disclosures: The authors have declared that no competing
interests exist.
Funding/Support: This material was unfunded at the time of manu-script preparation.
Additional Contributions: We gratefully acknowledge Annett Elsner
and John W. Michael for preparation of the manuscript.
Institutional Review: This study was approved by the Medical Fac-ulty on the Research Ethics Committee of the University of Göttingen,
and all investigations were performed in accordance with the
approved protocol to ensure that ethical and humane principles were
followed. Written informed consent was obtained from all participants
for participation and publication, including publication of photo-graphs and other visual depictions of subjects.
Participant Follow-Up: The authors do not plan to inform partici-pants of the publication of this study.
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DOI:10.1682/JRRD.2009.05.0067

Session 42
 - Osteoarthritis II
- VALENCIA B & C, Wed 8:00 AM - 10:00 AM
0262 46th Annual Meeting, Orthopaedic Research Society, March 12-15, 2000, Orlando, Florida

VALGUS BRACING FOR KNEE OSTEOARTHRITIS:
A BIOMECHANICAL AND CLINICAL OUTCOME STUDY
+*Otis, J C (A-Bledsoe Brace Systems and the Clark, Dana and Friese Foundations); *Backus, S I; *Campbell, D A; *Furman, G L (A-Bledsoe Brace Systems);
*Garrison, G (A-Bledsoe Brace Systems); *Warren, R F; *Wickiewicz, T L
+*Hospital for Special Surgery, New York, NY. 535 East 70th St./New York, NY 10021, 212 606-1088, Fax: 212 606-1490, otisj@hss.edu
Introduction:Valgus bracing has been used as a treatment for patients with
medial compartment OA for several years with variable amounts of pain
relief, functional improvement, and changes in medial joint loads. The basic
biomechanical philosophy is to apply a valgus load or correction about the
knee to partially offset the varus moment that the knee is subjected to during
the stance phase of gait. In doing so, joint compressive load is shifted from
the medial compartment to the lateral compartment. The efficacy of valgus
bracing using the Generation II Unloader brace has been previously
documented in an instrumented study of the brace in subjects with isolated
medial compartment osteoarthritis[1]. Patients reported a decrease in pain and
improvement in the performance of functional activities. The degree of pain
relief and functional improvement varied across subjects, however, as did
changes in the calculated medial joint loads.
The common denominator in the design of these braces is that, in theory, they
apply a valgus load about the knee. It is unclear, however, whether or not the
applied valgus load is actually a factor responsible for the clinical success of
valgus bracing. Other factors, e.g., the additional stability offered by the
brace or increased proprioception, may be responsible for the success of the
treatment. This randomized prospective controlled study examines the
hypothesis that valgus loading is responsible for the success observed
clinically. This is accomplished by comparing clinical outcomes of patients
treated with valgus bracing versus outcomes of those treated with sham
bracing (no valgus correction).
Methods:To date, forty-four subjects, 27 males and 17 females, (age 52 ± 11
years, ht 1.8 ± 0.1 m , wt 86 ± 16 kg) have been tested. Inclusion criteria
were: males and females 21 years of age or older; medial compartment knee
OA; and referral for unilateral bracing. Exclusion criteria were: fixed knee
flexion deformity greater than 5°; leg length discrepancy greater than 2 cm;
other neuromuscular deficits; skin or peripheral vascular disease preventing
brace application; and current lower extremity orthopaedic deficits, except for
the contralateral knee.
Subjects received an off-the-shelf, adjustable hinge correction, Bledsoe
Thruster brace at no charge. The braces were fit from the same orthotic
department. Informed consent was obtained, and treatment was randomized
into two groups. The treatment group received the prescribed amount of
valgus correction applied. A control group was fit with the same model brace
with no valgus correction applied (sham bracing). Upon completion of gait
analysis, the braces for these subjects were adjusted to the prescribed amount
of correction. The treatment group assignment was known only to the
orthotist. When a subject received the brace, an initial questionnaire was
completed that included visual analog scales for pain and function during
walking. Subjects used the brace according to physician referral when needed
during activities of daily living and sports. After at least two weeks of brace
use, gait analysis was conducted. Time-distance parameters, knee joint
kinematics and kinetics, and brace loads from instrumented braces were
determined. The questionnaire was also re-administered at this time.
Randomization was done with a block design. Each of the blocks consists of
two treatment cells that contain five subjects. Subjects are randomly assigned
to a cell when recruited for the study. At that time the leg is measured for the
brace, informed consent is obtained and each participant completes the initial
questionnaire. Included in the questionnaire were visual analog scales (VAS)
for pain at rest, during walking, stair negotiation and usual sports activity.
Subjects used the brace according to physician referral when needed during
activities of daily living, walking, exercising and sports. After two weeks, but
less than eight weeks, of using the brace, gait analysis was conducted with the
subject unbraced and braced. Time-distance parameters, knee joint
kinematics and kinetics, brace loads from instrumented braces and calculated
knee joint compartment loads were determined. A follow-up questionnaire
was also completed at the time of testing.
Each of the braces is instrumented to record bending moments. Three-dimensional video based gait analysis using a six-camera system (Motion
Analysis Corporation, Santa Rosa, CA) and two force platforms (Bertec, OH)
was completed at self-selected free speed walking. A minimum of three trials
of force platform contacts was collected for each of two conditions: braced
and unbraced free speed walking. A 2m by 1m by 2m volume was calibrated
and a standard unilateral lower extremity 11 marker set (Cleveland Clinic
configuration) was used. Hip, knee and ankle joint centers were calculated
according to standardized methodology. Pelvis and unilateral lower extremity
(hip, knee and ankle) joint kinematics, and unilateral lower extremity (hip,
knee and ankle) joint kinetics were determined. Only the affected lower
extremity was measured.
Average kinematics, kinetics and brace loads for each subject, for three trials
at each condition were calculated. In order to measure similarity between
treatment groups, two-sample t-test and chi square analysis were used to
compare demographics, time-distance parameters (velocity, cadence, and
stride length), and the pre-braced questionnaire results. Results were analyzed
to determine whether or not clinical success as measured by pain relief was
associated with treatment (t-test). In addition, the degree of load sharing by
the brace was analyzed for the two groups (bootstrapped 90% confidence
interval). A significance level of 0.05 was used.
Results:There were no differences between groups with respect to
demographics or time-distance parameters during braced or unbraced walking.
The unbraced and braced velocities for the control group were 113 and 112
cm/s, respectively. For the treatment group, these values were 113 and 114
cm/s, respectively. Changes in pain score during walking were –2.8 ± 3.0 and
–2.1 ± 2.1 in the control and treatment group respectively. A two-sample t-test demonstrated no difference in the pain relief or function for the two
groups. The average varus moment taken up by the brace during the stance
phase in the control group was –3.3 ± 2.9 Nm versus –2.9 ± 3.0 Nm for the
treatment group. A test of the difference between these means yielded p =
0.66.
Discussion: The results indicated that while load sharing occurred when
wearing the brace for all subjects (-3.3 ± 3.0 Nm, p < 0.001) there was no
difference between groups in the amount of valgus correction. The lack of
differences in pain and function between the two groups was consistent with
the comparable brace loads in both groups. As in previous work, there was
large variability in pain relief although both groups demonstrated significant
improvement between their pre and post visits (p < 0.001). The population is
representative of the spectrum of patients treated with valgus bracing and seen
by physical therapists during the course of conservative management. Valgus
bracing for medial compartment knee OA continues to be another option in
the treatment of these patients. A third group of 25 patients with valgus
correction greater than that used in the current treatment group is currently
being added to the study.
Reference:1. Otis, J.C., et al.: Gait and Posture, Vol. 4, No. 2, p. 189, 1996.

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