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Is there an alternative to the full-leg radiograph for determining knee joint alignment in osteoarthritis.

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Arthritis & Rheumatism (Arthritis Care & Research)
Vol. 55, No. 2, April 15, 2006, pp 306 –313
DOI 10.1002/art.21836
© 2006, American College of Rheumatology
ORIGINAL ARTICLE
Is There an Alternative to the Full-Leg Radiograph
for Determining Knee Joint Alignment in
Osteoarthritis?
RANA S. HINMAN, RACHEL L. MAY,
AND
KAY M. CROSSLEY
Objective. To assess the concurrent validity of alternative measures of frontal plane knee alignment, namely the
radiographic anatomic axis and 5 clinical measures, in medial compartment knee osteoarthritis (OA) as compared with
the mechanical axis on radiograph.
Methods. Forty individuals (mean ⴞ SD age 64.7 ⴞ 9.4 years) with symptomatic medial knee OA participated. Knee
alignment was measured according to the following methods: lower-limb mechanical axis on radiograph, lower-limb
anatomic axis on radiograph, visual observation, distance between medial knee joint lines or medial malleoli using a
calliper, distance between a plumb line and medial knee joint line or malleolus using a calliper, tibial alignment using
a gravity inclinometer, and lower-limb alignment using a goniometer. Data were analyzed using Pearson’s correlation
coefficient or Spearman’s rho correlation coefficient and simple linear regression.
Results. The anatomic axis best correlated with the mechanical axis (r ⴝ 0.88), followed closely by the inclinometer
method (r ⴝ 0.80). Other clinical measures of alignment that were significantly associated with the mechanical axis were
the calliper method, the plumb-line method, and visual observation (r ⴝ 0.76, 0.71, and ⴚ0.52, respectively). However,
the goniometer method failed to correlate.
Conclusion. The anatomic axis on radiograph and the inclinometer method appear to be valid alternatives to the
mechanical axis on full-leg radiograph for determining frontal plane knee alignment in medial knee OA. These
alternative methods of measuring knee alignment may increase the assessment of this parameter by clinicians and
researchers alike, given that malalignment is an important indicator of disease progression and treatment outcome.
KEY WORDS. Knee; Osteoarthritis; Alignment; Validity; Radiograph.
INTRODUCTION
Knee osteoarthritis (OA) is a common affliction in the
elderly population worldwide, affecting approximately
one-third of individuals ⬎60 years of age (1). Typical
consequences for the patient with knee OA include pain,
reduced physical function, disability, and ultimately decreased quality of life. A range of musculoskeletal impairSupported by funding from The University of Melbourne
and the Arthritis Foundation of Australia.
Rana S. Hinman, BPhysio(Hons), PhD, Rachel L. May, Kay
M. Crossley, BAppSci(Physio), GradDip(Physio), PhD: Centre for Health, Exercise and Sports Medicine, School of
Physiotherapy, The University of Melbourne, Victoria, Australia.
Address correspondence to Rana S. Hinman, BPhysio(Hons), PhD, Centre for Health Exercise and Sports Medicine, School of Physiotherapy, The University of Melbourne,
Parkville, Victoria, 3010, Australia. E-mail: ranash@
unimelb.edu.au.
Submitted for publication May 20, 2005; accepted in revised form August 26, 2005.
306
ments are also associated with the condition. These may
include, but are not limited to, muscle weakness, impaired
proprioception, altered gait patterns, and joint laxity (2–
6). Because there is no cure for OA, current management
strategies aim to relieve symptoms and slow the progression of the disease (7,8).
Joint malalignment in the frontal plane is a frequent
manifestation of knee OA, but it is not clear whether it
precedes disease onset or occurs as a consequence. Varus
malalignment appears to be the most common deformity,
and has been reported in 53–76% of individuals with knee
OA (9 –11). This is probably a result of the high prevalence
of medial tibiofemoral OA relative to lateral compartment
disease (12,13), whereby progressive cartilage loss on the
medial side may lead to increasing varus deformation of
the knee joint. Frontal plane malalignment has important
biomechanical consequences because it influences loading
across the knee joint during weight bearing. In the neutrally aligned knee, the ground reaction force vector passes
medially to the joint center, creating an adduction moment
that increases medial compartment forces relative to lat-
Determining Knee Alignment in OA
eral (14). When the knee is malaligned in the varus direction, the moment arm for ground reaction force vector is
increased, resulting in a higher adduction moment than
that observed in the neutral knee. Valgus malalignment
results in a more laterally positioned ground reaction force
vector and increases forces across the lateral knee compartment.
OA is believed to result from the interplay between
alterations in loading across the knee joint surfaces and
genetic susceptibility (15). Although many factors, such as
obesity and repetitive activity (16), may increase joint
loading and lead to the development or progression of
knee OA, malalignment is a strong predictor of disease
progression. In a study of 230 individuals with knee OA,
Sharma et al (17) demonstrated that varus malalignment at
baseline was associated with a 4-fold increase in the risk of
medial compartment progression at 18 months as measured by joint space narrowing on radiograph. Valgus malalignment was associated with an almost 5-fold increase in
the risk of lateral compartment progression. These findings
are supported by findings from other studies (11,18). Similar associations between malalignment and risk of OA
progression have also been reported for the patellofemoral
joint (9). No study to date has evaluated the effect of knee
malalignment on incident knee OA.
In knee OA, malalignment in both knees of ⬎5° in either
a varus or valgus direction is associated with significantly
greater functional decline over time when compared with
less malaligned knees (17). Malalignment adversely influences the outcome of surgical interventions for knee OA,
such as arthroplasty and high tibial osteotomy (19,20). It
also mediates the effect of body weight on disease progression, whereby the detrimental effect of body mass index on
progression appears to be limited only to knees with moderate malalignment (11).
Despite the importance of identifying malalignment in
patients with knee OA, assessment of malalignment remains problematic. The gold standard for assessment is
the weight-bearing full-leg radiograph, which allows the
mechanical axis of the lower limb to be determined. This
procedure is costly, exposes the patient’s pelvis to ionizing
radiation, and is not feasible for many health care professionals and researchers who are unable to directly request
radiographs funded by national health care systems. Furthermore, the evaluation of alignment from the radiograph
requires extrapolation of the femoral and tibial mechanical
axes using bony landmarks, thus it is somewhat time consuming for the clinician or researcher to determine. Determination of knee alignment using the anatomic axis
(21,22) is possible from a single knee radiograph. This is a
cheaper alternative, exposes the patient to less radiation,
and is a routine test ordered for many patients with knee
OA; however, the validity of this technique for measuring
the mechanical axis in knee OA has only been reported in
abstract form (23). Several clinical measures of knee alignment have been reported in the literature, including goniometry (24), visual observation (25), and calliper methods
of measurement (26). Although such methods offer great
clinical application with regard to cost, simplicity of use,
307
and speed of result, no clinical measure of knee alignment
has been validated against the mechanical axis determined
by radiography.
This study assessed the concurrent validity of the radiographic anatomic axis and 5 clinical measures of frontal
plane knee alignment in medial compartment knee OA.
The aim of this study was to determine the correlation
between these measures and the mechanical axis on radiograph, which is considered the gold standard for determining knee alignment.
PATIENTS AND METHODS
Participants were recruited for a cohort study evaluating
laterally wedged insoles. Forty participants ⬎50 years of
age with medial compartment knee OA were recruited
from the community by newspaper advertisements. Diagnosis was based on the American College of Rheumatology
classification criteria (27). Participants were included if
they had osteophytes in the medial tibiofemoral joint compartment on radiograph, experienced knee pain on most
days of the past month, and reported an average pain while
walking of ⬎3 on an 11-point Likert scale in the last
month. Participants were excluded if they reported a previous hip or knee joint replacement, hip or lumbar spine
arthritis or other joint pathology causing lower-limb pain,
a knee injection in the preceding 6 months, knee surgery in
the preceding 6 months, use of shoe orthotics in the preceding 6 months, a body mass index ⬎36 kg/m2, use of gait
aid, or an inability to understand English.
Ethics approval was obtained from the University of
Melbourne’s Human Research Ethics Committee, and from
the Department of Human Services’ Radiation Advisory
Committee. All participants provided written informed
consent prior to entering the study.
Knee joint alignment as determined by mechanical axis.
A single full-leg, anteroposterior, weight-bearing radiograph of the symptomatic lower limb was obtained. Either
a 35.6 ⫻ 91.4 – cm graduated-grid cassette or a standard
(nongraduated) 35.6 ⫻ 129.5– cm cassette was used, depending on the height of the participant. Care was taken
when using the nongraduated cassette, such that clarity of
the femoral head, knee joint, and talus was achieved on all
images. Participants stood barefoot with the knee in full
extension, and were positioned with the tibial tuberosity
facing the x-ray beam (17). Weight was distributed equally
over both feet. The x-ray tube was positioned at a distance
of 2.44 meters from the cassette, and depending on individual limb characteristics, a setting of ⬃25 mA/second
and 100 kilovolts was applied. Foot maps were drawn for
each participant to enable exact lower limb repositioning
for the subsequent clinical alignment measures.
Alignment was defined as the angle of intersection of the
femoral and tibial mechanical axes according to the
method of Sharma et al (17). To determine the mechanical
axis of the femur, a line was drawn from the center of the
femoral head to the center of the femoral intercondylar
notch. The femoral head center was located using a series
of concentric circular hip templates. A second line from
308
Hinman et al
Figure 1. Determination of knee alignment using A, the calliper method (for a varus
knee), B, the plumb-line method (for a varus knee), C, the inclinometer method, and
D, the goniometer method.
the center of the tibial spines to the center of the ankle
talus established the mechanical axis of the tibia. Alignment was recorded to the nearest half degree. Varus and
valgus malalignment are indicated by values ⬍180° and
⬎180°, respectively. The mechanical axis was determined
by a single investigator (RSH) who was blinded to scores
that were obtained with all other measures of alignment. In
a sample of 14 radiographs randomly selected from the
study cohort, intrarater reliability for determining mechanical axis was high (intraclass correlation coefficient
[ICC] 0.98).
Knee joint alignment as determined by anatomic axis.
Using the full-leg radiograph, the anatomic axis was determined based upon the methods of Moreland et al (22). The
femoral anatomic axis was found by drawing a line from
the center of the tibial spines to a point 10 cm above the
tibial spines, midway between the medial and lateral femoral surfaces. For the tibial anatomic axis, a line was
drawn from the center of the tibial spines to a point 10 cm
below the tibial spines, midway between the medial and
lateral tibial surfaces. The angle of intersection of the axes
was determined by the same investigator (RSH) who found
an ICC of 0.95 with this measure.
Knee joint alignment as determined by clinical measures. A single investigator (RLM) blinded to radiographic
measures performed 5 clinical measures of alignment in
all patients (except the goniometer method, which was
only performed on 26 participants). For all measures, participants stood with their weight distributed equally between the lower limbs, with knees extended to replicate
positioning for mechanical alignment via radiograph. Varus malalignment was scored negatively and valgus positively. Reliability of the clinical measures was evaluated in
a separate cohort of 10 participants (mean age 64 years, 5
women) with symptomatic knee OA recruited from the
community prior to the study.
Magee’s method. The method described by Magee (25)
categorizes varus, valgus, or neutral alignment based on
visual observation (␬ ⫽ 1 in our laboratory). Participants
adducted their lower limbs slowly until either the knees or
ankles touched. When the medial malleoli touched first,
the participant was classified as having varus malalignment. If the knees touched first, the participant was classified as having valgus malalignment. If knees and ankles
touched simultaneously, alignment was recorded as neutral.
Calliper method. Malalignment that was evident using
Magee’s method was quantified using a calliper marked in
Determining Knee Alignment in OA
1-mm increments (recorded in cm to 1 decimal place)
based on the methods of Cibere et al (24). In participants
with varus knees, the distance between the medial knee
joint lines was recorded (Figure 1A). For valgus knees, the
distance between the medial malleoli was recorded. This
method was found to be reliable in our laboratory (ICC
0.97).
Plumb-line method. Because the calliper method is influenced by the alignment of both knee joints, a modification of this method was used to more accurately assess
alignment of the affected knee only, based on the methodology of Jonson and Gross (26). A plumb line was positioned between the lower limbs. For varus knees, the distance between the plumb line and the symptomatic medial
knee joint line was measured using a calliper (recorded in
cm to 1 decimal place) (Figure 1B). For valgus knees, the
distance between the plumb line and the medial malleolus
of the symptomatic side was measured using a calliper.
This method was found to be reliable in our laboratory
(ICC 0.95).
Inclinometer method. This novel methodology was devised by the authors to assess orientation of the tibia with
respect to the vertical. A gravity inclinometer (Acuangle,
Isomed, Portland, OR) was attached to a set of callipers.
Participants were positioned on the foot map, and the
tibial tuberosity and neck of talus were identified. The
calliper arms were placed on these landmarks (Figure 1C).
The angle of the tibia with respect to the vertical (180°)
was recorded. This method was found to be reliable in our
laboratory (ICC 0.94).
Goniometer method. Alignment determined by a standard long-arm goniometer was based on the method described by Cibere et al (24). Participants stood on the foot
maps. The axis of the goniometer was positioned over the
center of the patella, and the arms were aligned with the
mid-thigh above the knee and with the patella tendon
below the knee (Figure 1D). Angles were recorded to the
nearest degree, with 180° regarded as neutral. This method
was found to be reliable in our laboratory (ICC 0.84).
Descriptive characteristics. Severity of pain, stiffness,
and limitation in physical function were assessed using
the Western Ontario and McMaster Universities Osteoarthritis Index, a reliable and valid disease-specific questionnaire (28). Severity of OA on the radiograph was assessed
using the Kellgren and Lawrence grading system, whereby
0 ⫽ normal; 1 ⫽ possible osteophytes; 2 ⫽ minimal osteophytes and possible joint space narrowing; 3 ⫽ moderate
osteophytes, some narrowing, and possible sclerosis; and
4 ⫽ large osteophytes, definite narrowing, and severe sclerosis (29).
Statistical analysis. Data were analyzed using the SPSS
version 11.0 (SPSS, Chicago, IL). Descriptive statistics
were used for participant characteristics and scores obtained on all alignment measures. Correlations between
mechanical alignment and the tested alignment methods
were determined using Pearson’s correlation coefficients,
excluding the Magee method, which was analyzed using
Spearman’s rho. Simple linear regression was used to de-
309
velop regression equations for statistically significant relationships (excluding the Magee method). Correlation coefficients of 0.5– 0.75 were regarded as good, and values
⬎0.75 were regarded as excellent (30). P values less than
0.05 were regarded as significant.
RESULTS
Participant characteristics are presented in Table 1. The
cohort comprised more women than men. Participants
were generally overweight (31) and reported moderate levels of pain, stiffness, and physical limitation. A range of
radiographic severity was evident, with the majority (68%)
of participants demonstrating moderate-severe changes on
radiograph (grade 3 or 4).
Thirty-six (90%) participants had a varus mechanical
axis, 3 were valgus (8%), and 1 was neutral (2%). The
entire cohort demonstrated a mean varus malalignment of
5.8° from the neutral position, based on the mechanical
axis on radiograph. Alignment characteristics of the cohort
according to each measurement technique utilized are presented in Table 2.
There was an excellent correlation between the anatomic axis and the mechanical axis (r ⫽ 0.88, P ⬍ 0.001)
(Figure 2). Regression analysis defined this relationship
according to the following equation: mechanical axis ⫽
0.915(anatomic axis) ⫹ 13.895. The anatomic axis accounted for 77% of the total variance in mechanical axis
scores.
Of the 5 clinical measures, the inclinometer method
demonstrated the strongest correlation with the mechanical axis, with a correlation coefficient of 0.80 (P ⬍ 0.001)
(Figure 3). Regression analysis defined this relationship
with the following equation: mechanical axis ⫽ 1.153(inclinometer angle) ⫺ 28.716. The inclinometer angle accounted for 64% of the total variability in mechanical axis
Table 1. Participant characteristics*
Characteristic
Value
Age, years
Height, meters
Weight, kg
Body mass index, kg/m2
Reported symptom duration, years
WOMAC score†
Pain subsection
Stiffness subsection
Physical function subsection
Sex, male:female
Osteoarthritis severity, no.‡
Grade 1
Grade 2
Grade 3
Grade 4
64.7 ⫾ 9.4
1.64 ⫾ 0.09
79.1 ⫾ 12.0
29.6 ⫾ 4.2
8.8 ⫾ 7.9
9⫾3
4⫾1
30 ⫾ 11
16:24
3
10
11
16
* Values are the mean ⫾ SD unless otherwise indicated. WOMAC ⫽
Western Ontario and McMaster Universities Osteoarthritis Index.
† Score range includes pain (0 –20), stiffness (0 – 8), and physical
function (0 – 68). Higher scores indicate worse symptoms.
‡ Radiographic severity according to Kellgren and Lawrence grading system, where higher grades indicate more severe disease.
310
Hinman et al
Table 2. Alignment characteristics of the cohort
according to each measurement procedure*
Method
Value
Mechanical axis, °†
Anatomic axis, °†
Calliper method, cm†
Plumb-line method, cm†
Inclinometer, °†
Goniometer, °†
Magee’s method, no. (%)
Varus
Valgus
Neutral
174.2 ⫾ 4.9 (164.5–186.0)
175.2 ⫾ 4.7 (166.0–185.5)
⫺0.8 ⫾ 3.5 (⫺7.6–7.5)
⫺0.4 ⫾ 1.9 (⫺3.3–3.9)
176 ⫾ 3 (169–182)
180 ⫾ 6 (167–192)
25 (63)
13 (33)
2 (4)
* Values are the mean ⫾ SD (range) unless otherwise indicated.
† Lower values represent a more varus knee alignment.
Figure 3. Scatterplot depicting the relationship between the inclinometer and the mechanical axis (n ⫽ 40).
The mechanical axis, as determined by the full-leg radiograph, is regarded as the gold standard for measuring knee
joint alignment in the frontal plane. This study evaluated
the criterion-related validity of 6 alternative measures for
assessing malalignment, as compared with the mechanical
axis. An alternative radiographic measure, the anatomic
axis, was tested, as were 5 clinical measures of alignment
(the Magee, calliper, plumb-line, inclinometer, and goniometer methods). Not surprisingly, the anatomic axis best
correlated with the mechanical axis, accounting for 77% of
the total variance in mechanical axis score. Importantly, 2
clinical measures were shown to be valid indicators of the
mechanical axis, namely the inclinometer and calliper
methods. Although the plumb-line and Magee methods
correlated significantly with the mechanical axis, these
relationships were weaker than those demonstrated by the
former clinical methods. The goniometer method used in
this study was not found to be a valid measure of mechanical axis.
Participants in this study were symptomatic and demonstrated medial tibiofemoral joint osteophytes. The authors believe the study cohort accurately reflects the wider
knee OA population given the predominance of women in
the sample, the fact that participants were generally overweight with moderately severe symptoms, and the wide
range of radiographic severity of disease that was evident.
The study sample demonstrated a mean mechanical axis of
174.2°, indicating an average varus malalignment of 5.8°.
This is greater than that of healthy individuals who generally demonstrate only a slight varus angulation of 1–2°
(21,22,32). These findings are in agreement with other
studies involving knee OA participants. Miyazaki et al (33)
reported a mean varus malalignment of 6.5° in their sam-
Figure 2. Scatterplot depicting the relationship between the anatomic axis and mechanical axis (n ⫽ 40).
Figure 4. Scatterplot depicting the relationship between the calliper method and the mechanical axis (n ⫽ 40).
scores. An excellent correlation with the mechanical axis
was also observed for the calliper method (r ⫽ 0.76, P ⬍
0.001) (Figure 4), which accounted for 58% of the total
variation in mechanical axis score. The relationship between the calliper reading and the mechanical axis was
defined with the following equation: mechanical axis ⫽
1.049(calliper reading) ⫹ 175.049. A good correlation was
evident between the mechanical axis and the plumb-line
method (r ⫽ 0.71, P ⬍ 0.001) (Figure 5), generating a
relationship defined with the following equation: mechanical axis ⫽ 1.803(plumb-line score) ⫹ 175.006. The plumbline method accounted for 50% of total variance in mechanical axis. In contrast, Magee’s method (visual
observation) was found to have a weaker, although still
statistically significant, relationship with the mechanical
axis (r ⫽ ⫺0.52, P ⫽ 0.001), accounting for only 27% of the
total variability in mechanical axis. No relationship was
observed between the goniometer method and the mechanical axis (r ⫽ 0.32, P ⫽ 0.12) (Figure 6).
DISCUSSION
Determining Knee Alignment in OA
Figure 5. Scatterplot depicting the relationship between the
plumb-line method and the mechanical axis (n ⫽ 40).
ple of 106 patients with medial knee OA, Sharma et al (34)
reported a mean varus malalignment of 5.1° in their group
of 236 patients with tibiofemoral OA, and Cooke et al (32)
reported a mean varus angulation of 3.95° in their 167
participants with symptomatic OA.
Few studies have investigated the validity of methods
for measuring knee alignment in patients with knee OA.
One study, reported in abstract form, also compared the
anatomic axis and a goniometer method with the mechanical axis in a cohort with symptomatic knee OA (23). In
contrast to the present study, anatomic axis was measured
using a semiflexed knee radiograph. Similar to the present
findings, the authors demonstrated a significant correlation between the anatomic and mechanical axes (r ⫽ 0.74).
In comparison, the present study revealed a much stronger
correlation between anatomic and mechanical axes on the
full-leg radiograph (r ⫽ 0.88), which is probably due to the
fact that the lower-limb position on radiograph was identical for the calculation of each angular measure. Predictive validity of the anatomic axis on an extended-knee
radiograph has previously been demonstrated by Cicuttini
et al (18) who demonstrated that baseline anatomic axis
was correlated with change in cartilage volume over time.
The goniometer method utilized by McDaniel et al (23)
was also slightly different from that used in the present
study. The lower goniometer arm was positioned along the
tibial shaft, in contrast to the present study, which aligned
the arm with the patellar tendon (selected because of the
high reliability reported with this method in knee OA
[24]). Whereas McDaniel et al (23) reported a strong corre-
Figure 6. Scatterplot depicting the relationship between the goniometer method and the mechanical axis (n ⫽ 26).
311
lation between their goniometer method and the mechanical axis (r ⫽ 0.72), we were unable to demonstrate a
significant correlation using the present methodology (r ⫽
0.32). During data collection, it was observed that the
patellar tendon did not always align with the tibial shaft.
One possible explanation for this phenomenon may be the
presence of patellar subluxation (35), which may alter the
angle of the patellar tendon with respect to the tibial shaft,
thus generating goniometer scores that do not accurately
reflect underlying skeletal alignment.
Results of this study demonstrated that both the inclinometer and calliper methods are valid measures of alignment in knee OA. A novel methodology using a gravity
inclinometer was devised by the authors based on the
assumption that tibial alignment with respect to the vertical reflects the tibial mechanical axis. Obtained results (r ⫽
0.80) appear to support this assumption. The calliper
method was also observed to be a valid measure of the
mechanical axis. This method has been reported with respect to knee OA in terms of its reliability (24) but not
validity; therefore, comparison of the present findings
with others is not possible. Compared with the inclinometer and calliper methods, the plumb-line and Magee
methods were not as valid for the measurement of knee
alignment. These latter methods have been reported as
reliable in young healthy individuals (26), but to the authors’ knowledge, they have not previously been validated
in any population. The somewhat more complex setup for
the plumb-line measure, which allows greater capacity for
measurement error, probably accounts for this method’s
slightly poorer validity compared with the more simple
calliper method. Magee’s method is dependent upon the
patient and investigator accurately identifying the first
point of soft tissue contact between either the medial malleoli or the medial knees. Excess soft tissue at the medial
knee may lead to a false classification of valgus malalignment, even though the underlying skeletal structure may
indicate a varus malalignment.
There are several limitations to this study. Due to the
differing soft tissue properties across the lower limb from
the hip to the ankle, a graduated-grid cassette is advocated
for full-leg radiographs to ensure clarity of image (22). The
35.6 ⫻ 91.4 – cm graduated-grid cassette available for use
in this study was adequate for shorter participants but not
for their taller counterparts. Unfortunately, a longer graduated-grid cassette was not available, therefore taller participants underwent radiography using a nongraduated
cassette. Although all radiographs of taller participants
were carefully monitored for image clarity, it is possible
that mechanical axes determined from these films may not
have been as accurate as those determined for shorter
participants. The general unavailability of sufficiently long
graduated-grid cassettes further supports the need for alternative measures of knee alignment, such as the anatomic axis, which requires only a standard nongraduated
cassette to image the knee joint. Only 3 participants demonstrated valgus mechanical malalignment, probably because the selection criteria were biased towards medial
tibiofemoral joint OA. Therefore, the present findings pertain primarily to the validity of methods for measuring
varus malalignment. It is unlikely that results should differ
312
for valgus malalignment; however, future research should
focus on evaluating the validity of the anatomic axis, the
inclinometer, and calliper methods for patients with knee
OA with valgus malalignment.
The findings in this study have important clinical implications. Several alternative methods for evaluating frontal plane knee alignment in OA have been identified, including the use of an extended anteroposterior knee
radiograph (which allows visualization of the lower limb
10 cm above and below the knee), an inclinometer, or
callipers. Advantages of the knee radiograph over the the
full-leg radiograph, which is the gold standard method,
include reduced cost to the patient, researcher, and/or
health care system; reduced exposure of the patient to
ionizing radiation (particularly around the pelvis); and no
problem with lack of a long graduated-grid cassette hampering determination of bony landmarks. The knee radiograph forms part of the standard radiographic examination
for knee OA, therefore extra radiographs just to determine
knee alignment are not needed. Unfortunately, calculation
of alignment from the knee radiograph is just as cumbersome and time consuming as that from a full-leg radiograph, requiring the clinician/researcher to carefully locate 4 bony landmarks, draw lines to identify the tibial and
femoral axes, and finally measure the angle of intersection
between the axes. In contrast to radiographic methods, the
inclinometer and calliper methods of measuring alignment
generate instant results, are quick to administer, are inexpensive (involving no cost to the patient/health care system and only a small outlay by the clinician/researcher to
purchase the equipment required initially), and do not
expose the patient to radiation. The inclinometer offers
advantages over the calliper method because it is less
likely to be adversely influenced by soft tissue characteristics of the lower limb, hence its slightly greater correlation with the mechanical axis. However, there is a greater
risk of misclassification when using these clinical measures of alignment rather than the anatomic axis, given the
lower correlation observed with the mechanical axis
(0.76 – 0.80 versus 0.88). Further studies are needed to
determine whether significant misclassification does in
fact occur, and to determine its consequences. Clinical
measures of alignment are probably no substitute for radiographic measures in surgical procedures where precise
measures of frontal plane malalignment are required for
optimal outcome.
In conclusion, this study demonstrated that the anatomic axis, inclinometer, and callipers are valid measures
of determining knee alignment in OA. Clinically, such
methods may increase assessment by clinicians and researchers of this important parameter in patients with
knee OA. Future research should evaluate the predictive
validity of the clinical measures with regard to disease
progression and functional decline over time.
ACKNOWLEDGMENTS
The authors would like to thank Tim Wrigley for his technical input, Ben Metcalf and Georgie Kemp for their assistance with data collection, and Phil Wood and the radiol-
Hinman et al
ogy staff at Royal Melbourne Hospital for their help with
the radiographs.
REFERENCES
1. Felson DT, Naimark A, Anderson J, Kazis L, Castelli W,
Meenan RF. The prevalence of knee osteoarthritis in the
elderly: The Framingham Osteoarthritis Study. Arthritis
Rheum 1987;30:914 – 8.
2. Hassan BS, Mockett S, Doherty M. Static postural sway, proprioception, and maximal voluntary quadriceps contraction
in patients with knee osteoarthritis and normal control subjects. Ann Rheum Dis 2001;60:612– 8.
3. Messier SP, Loeser RF, Hoover JL, Semble EL, Wise CM.
Osteoarthritis of the knee: effects on gait, strength, and flexibility [published erratum appears in Arch Phys Med Rehabil
1992;73:252]. Arch Phys Med Rehabil 1992;73:29 –36.
4. O’Reilly SC, Jones A, Muir KR, Doherty M. Quadriceps weakness in knee osteoarthritis: the effect on pain and disability.
Ann Rheum Dis 1998;57:588 –94.
5. Sharma L. Proprioceptive impairment in knee osteoarthritis.
Rheum Dis Clin North Am 1999;25:299 –314.
6. Sharma L, Lou C, Felson DT, Dunlop DD, Kirwan-Mellis G,
Hayes KW, et al. Laxity in healthy and osteoarthritic knees.
Arthritis Rheum 1999;42:861–70.
7. Jordan KM, Arden NK, Doherty M, Bannwarth B, Bijlsma JW,
Dieppe P, et al. EULAR recommendations 2003: an evidence
based approach to the management of knee osteoarthritis:
report of a task force of the Standing Committee for International Clinical Studies Including Therapeutic Trials (ESCISIT). Ann Rheum Dis 2003;62:1145–55.
8. American College of Rheumatology Subcommittee on Osteoarthritis Guidelines. Recommendations for the medical management of osteoarthritis of the hip and knee: 2000 update.
Arthritis Rheum 2000;43:1905–15.
9. Cahue S, Dunlop D, Hayes K, Song J, Torres L, Sharma L.
Varus–valgus alignment in the progression of patellofemoral
osteoarthritis. Arthritis Rheum 2004;50:2184 –90.
10. Cooke TD, Li J, Scudamore RA. Radiographic assessment of
bony contributions to knee deformity. Orthop Clin North Am
1994;25:387–93.
11. Felson DT, Goggins J, Niu J, Zhang Y, Hunter DJ. The effect of
body weight on progression of knee osteoarthritis is dependent on alignment. Arthritis Rheum 2004;50:3904 –9.
12. Ledingham J, Regan M, Jones A, Doherty M. Radiographic
patterns and associations of osteoarthritis of the knee in patients referred to hospital. Ann Rheum Dis 1993;52:520 – 6.
13. McAlindon TE, Snow S, Cooper C, Dieppe PA. Radiographic
patterns of osteoarthritis of the knee joint in the community:
the importance of the patellofemoral joint. Ann Rheum Dis
1992;51:844 –9.
14. Schipplein OD, Andriacchi TP. Interaction between active
and passive knee stabilizers during level walking. J Orthop
Res 1991;9:113–9.
15. Creamer P, Hochberg MC. Osteoarthritis. Lancet 1997;350:
503– 8.
16. Cooper C, Snow S, McAlindon TE, Kellingray S, Stuart B,
Coggon D, et al. Risk factors for the incidence and progression
of radiographic knee osteoarthritis. Arthritis Rheum 2000;43:
995–1000.
17. Sharma L, Song J, Felson DT, Cahue S, Shamiyeh E, Dunlop
DD. The role of knee alignment in disease progression and
functional decline in knee osteoarthritis [published erratum
appears in JAMA 2001;286:792]. JAMA 2001;286:188 –95.
18. Cicuttini F, Wluka A, Hankin J, Wang Y. Longitudinal study
of the relationship between knee angle and tibiofemoral cartilage volume in subjects with knee osteoarthritis. Rheumatology (Oxford) 2004;43:321– 4.
19. Ritter MA, Faris PM, Keating EM, Meding JB. Postoperative
alignment of total knee replacement: its effect on survival.
Clin Orthop Relat Res 1994;299:153– 6.
20. Yasuda K, Majima T, Tsuchida T, Kaneda K. A ten- to 15-year
follow-up observation of high tibial osteotomy in medial com-
Determining Knee Alignment in OA
21.
22.
23.
24.
25.
26.
27.
28.
partment osteoarthrosis. Clin Orthop Relat Res 1992;282:186 –
95.
Hsu RW, Himeno S, Coventry MB, Chao EY. Normal axial
alignment of the lower extremity and load-bearing distribution at the knee. Clin Orthop Relat Res 1990;255:215–27.
Moreland JR, Bassett LW, Hanker GJ. Radiographic analysis of
the axial alignment of the lower extremity. J Bone Joint Surg
Am 1987;69:745–9.
McDaniel GE, Vail TP, Kraus VB. Comparison of knee alignment angle by x-ray and goniometer [abstract]. Arthritis
Rheum 2004;50 Suppl 9:S343.
Cibere J, Bellamy N, Thorne A, Esdaile JM, McGorm KJ,
Chalmers A, et al. Reliability of the knee examination in
osteoarthritis: effect of standardization. Arthritis Rheum
2004;50:458 – 68.
Magee D. Orthopedic physical assessment. 2nd ed.
Philadelphia: W.B. Saunders; 1992.
Jonson SR, Gross MT. Intraexaminer reliability, interexaminer
reliability, and mean values for nine lower extremity skeletal
measures in healthy naval midshipmen. J Orthop Sports Phys
Ther 1997;25:253– 63.
Altman R, Asch E, Bloch D, Bole G, Borenstein D, Brandt K, et
al. Development of criteria for the classification and reporting
of osteoarthritis: classification of osteoarthritis of the knee.
Arthritis Rheum 1986;29:1039 – 49.
Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt
LW. Validation study of WOMAC: a health status instrument
313
29.
30.
31.
32.
33.
34.
35.
for measuring clinically important patient relevant outcomes
to antirheumatic drug therapy in patients with osteoarthritis
of the hip or knee. J Rheumatol 1988;15:1833– 40.
Kellgren JH, Lawrence JS. Radiological assessment of osteoarthrosis. Ann Rheum Dis 1957;16:494 –502.
Portney L, Watkins M. Foundations of clinical research: applications to practice. 2nd ed. Upper Saddle River (NJ): Prentice Hall Health; 2000.
National Health and Medical Research Council. Dietary
guidelines for older Australians. Canberra: Commonwealth of
Australia; 1999. p. 1– 40.
Cooke D, Scudamore A, Li J, Wyss U, Bryant T, Costigan P.
Axial lower-limb alignment: comparison of knee geometry in
normal volunteers and osteoarthritis patients. Osteoarthritis
Cartilage 1997;5:39 – 47.
Miyazaki T, Wada M, Kawahara H, Sato M, Baba H, Shimada
S. Dynamic load at baseline can predict radiographic disease
progression in medial compartment knee osteoarthritis. Ann
Rheum Dis 2002;61:617–22.
Sharma L, Cahue S, Song J, Hayes K, Pai YC, Dunlop D.
Physical functioning over three years in knee osteoarthritis:
role of psychosocial, local mechanical, and neuromuscular
factors. Arthritis Rheum 2003;48:3359 –70.
Harrison MM, Cooke TD, Fisher SB, Griffin MP. Patterns of
knee arthrosis and patellar subluxation. Clin Orthop Relat Res
1994;309:56 – 63.
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