An Examination of the Selective
Tissue Tension Scheme, With
Evidence for the Concept of a
Capsular Pattern of the Knee
Background and Purpose. The purpose of this study was to examine
whether there is evidence to support 2 elements of the passive-rangeof-motion (PROM) portion of Cyriax's selective tissue tension scheme
for patients with knee dysfunction: a capsular pattern of motion
restriction and the pain-resistance sequence. Subjects. O n e hundred
fifty-two subjects with unilateral knee dysfunction participated. The
subjects had a mean age of 40.0 years (SD=15.9, range=13-82).
Methods. Passive range of motion of the knee and the relationship
between the onset of pain and resistance to PROM (pain-resistance
sequence) were measured, and 4 tests for inflammation were used.
Interrater reliability was assessed on 35 subjects. Results. Kappa values
for the individual inflammatory tests ranged from .21 to .66 for
categorization of the joint as inflamed, based on at least 2 positive
inflammatory tests ( K = .76). Reliability of PROM measurements was
indicated by intraclass correlation coefficients of .72 to .97. Reliability
of measurements of the pain-resistance sequence was indicated by a
weighted kappa of .28. A capsular pattern, defined as a ratio of loss of
extension to loss of flexion during PROM of between 0.03 and 0.50,
was more likely than a noncapsular pattern in patients with an
inflamed knee or osteoarthrosis (likelihood ratio=3.2). An association
was found between a capsular pattern and arthrosis or arthritis.
Conclusion and Discussion. These findings provide evidence to support
the concept of a capsular pattern of motion restriction in persons with
inflamed knees or evidence of osteoarthrosis. [Fritz JM, Delitto A,
Erhard RE, Roman M. An examination of the selective tissue tension
scheme, with evidence for the concept of a capsular pattern of the
knee. Phys Ther. 1998;78:1046-1061.1
Key Words: Clinical decision making, Knee, Tests and measurements.
Julie M Fritz
Anthony Delitto
Richard E Erhard
Matthew Roman
Physical Therapy. Volume 7 8 . Number 10 . October 1998
he selective tissue tension scheme of James
Cyriaxl is an evaluation method commonly used
by physical therapists. Cyriax's scheme consists
of active-range-of-motion (AROM), passiverange-of-motion (PROM), and resistive tests, followed by
palpation of anatomical structures. According to Cyriax,
active movements indicate the patient's willingness to
move. the available AROM, and the muscular power
available. Resistive movements can be used, according to
Cyriax, to assess the status of the contractile structures
(muscle, tendon) around the j o i n t . l ( ~ p ~ ~Passive
-~~)
movements are supposed to test noncontractile structures. In Cyriax's scheme, palpation is performed to
detect any deformity or inflammatory signs, including
warmth or swelling. ( P ~ ~ )
In the assessment of PROM, Cyriax contended that the
examiner should assess the available PROM, the nature
of the end-feel for the motion, and the relationship of
the onset of pain with the onset of resistance during
PROh4 (pain-resistance sequence [PRS]). The PRS purportedly reflects the acuity of the inflammatory process.
Cyriax contended that pain occurring prior to resistance
to movement indicates an acutely inflamed joint, that
pain that is synchronous with resistance indicates a less
acutely inflamed joint, and that pain occurring after
resistance indicates a noninflamed joint.l(pi7) Cyriax
proposed that, by evaluating the PRS, the clinician can
judge the acuity of the patient's condition and can
determine how aggressively to proceed with treatment.
For example, if manual stretching of ajoint is to be used
to regain lost motion, an aggressive approach would be
indicated with a judgment of "pain after resistance,"
according to Cyriax's concept of the PRS.
Cyriax further recommended assessing passive motion
for each movement of ajoint in order to discern patterns
of motion restrictions. A "capsular pattern" is a proportional motion restriction unique to each joint that
indicates irritation of the entire synovial membrane or
joint capsule, as occurs with an active inflammatory
process (arthritis) o r degenerative joint changes
( a r t h r ~ s i s ) . ~ (According
p~~)
to Cyriax, motion restrictions in proportions other than the capsular pattern are
supposed to occur in lesions that are capable of restricting motion, but that are localized in such a way that the
whole joint is not involved. Cyriax stated that "noncapsular patterns" fall into 1 of 3 categories: ligamentous
adhesions (eg, posttraumatic medial collateral ligament
adhesion at the knee), internal derangements
(eg, meniscal tear), and extra-articular lesions (eg, bursitis, muscle i n j ~ r y ) . l ( p p ~H- e~ ~did
) not, however, s u p
ply any evidence to support this contention.
JM Fritz, PhD, PT, ATC, is Assistant Professor, Department of Physical Therapy, School of Health and Rehabilitation Sciences, Univerrity of
Pittsburgh, 6035 Forbes Tower, Pittsburgh, Pa 15260 (USA) (jfritz@pitt.edu).Address all correspondence to Dr Fritz.
A Delitto, PhD, PT, is Associate Professor and Chair, Department of Physical Therapy, School of Health and Rehabilitation Sciences, University
of Pittsburgh, Director of Research, Comprehensive Spine Center, University of Pittsburgh Medical Center, and Vice President for Education and
Research, CORE Network, Limited Liability Corporation, McKeesport, Pa.
RE Erhard, DC, PT, is Assistant Profrssor. Department of Physical Therapy, School of Health and Rehabilitation Sciences, University of Pittsburgh,
and Director of Physical Therapv and Chiropractic Senices, Comprehensive Spine Center, University of Pittsburgh Medical Center.
M Roman, PT, is Senior Physical Therapist, Rehability Center, Raleigh, NC.
This article was submitted August 18, 1997, and was accpPted May 7, 1998.
Physical Therapy . Volume 78 . Number 10 . October 1998
Fritz et al . 1047
Cyriax stated that the purposes of the selective tissue
tension scheme are (1) to clarify the acuity (or severity)
of the injury1(pi7)and (2) to identify the structure most
responsible for the patient's pain.l(p7" The degree of
severity is based largely on the PRS. According to Cyriax,
in order to identity the structure involved, the examiner
should consider whether a contractile structure or a
noncontractile structure is involved.l(pfi" If a noncontractile structure is thought to be involved, the
examiner is supposed to judge whether the pain arises
from a generalized involvement of the entire joint (ie,
the joint capsule or synovium) or from a more localized
pathology not involving the entire joint (eg, a ligamentous adhesion). ( ~ ~ ' ~ -Cyriax
7v
proposed that the later
decision is aided by the particular pattern of passive
motion restriction found on examination. According to
Cyriax, a capsular pattern of restriction is more indicative of involvement of the whole joint (eg, arthritis or
arthrosis), and a noncapsular pattern of restriction indicates involvement of specific structures around the joint,
such as soft tissue contracture or internal derangement.
For example, Cyriax defined the capsular pattern of the
knee as "great limitation of flexion and slight limitation
of e x t e n s i ~ n . " ~ (He
p ~did
~ ~ )not, however, operationally
define "great limitation" or "slight limitation." According to Cyriax, a patient with a substantial loss of flexion
and no loss of extension during PROM of the knee
would have a noncapsular pattern, and the limitation
would more likely be caused by a contracture of the
knee's extensor mechanism or an internal derangement
than by involvement of the whole joint (ie, capsule,
synovium). A patient with a capsular pattern of the knee
(gross loss of flexion, with a slight limitation of extension) would have pathology more likely involving the
joint capsule or synovium. According to Cyriax, joint
mobilization would be indicated for the patient with a
capsular pattern, with aggressiveness dictated by the
acuity of the inflammatory status, as determined by the
PRS. For the patient with a noncapsular pattern, treatment is supposed to be directed toward the pathology,
and techniques such as cross-friction massage or stretching of the contracted extensor mechanism would be
indicated. Cyriax supplied no data to support the effectiveness of these techniques.
There are 2 recent reports of attempts to evaluate
Cyriax's selective tissue tension scheme, and the results
vary. Pellecchia et a12 reported on the interrater reliability of examiners' classifications of patients with shoulder
pain, Active range of motion, PROM, and resistive range
of motion (ROM) were evaluated, and the therapists
placed the patients into a diagnostic category based on
the results. The authors reported agreement between
the 2 therapists regarding the diagnostic classification of
19 of the 21 patients tested, and they concluded that the
.
1048 Fritz et al
Cyriax evaluation scheme was highly reliable in the
assessment of shoulder pain.Wayes et al:3 evaluated
the passive component of Cyriax's scheme in patients
with osteoarthritis of the knee. The authors concluded
the validity of the passive components for identifying
patients with osteoarthritis of the knee was questionable."
The primary purpose of this study was to examine the
relationship between the ratio of PROM restrictions of
the knee and the expectation of a capsular pattern based
on Cyriax's definitions and, therefore, to examine one of
the premises of Cyriax's classification scheme. According
to Cyriax, a capsular pattern (ie, a great limitation of
flexion, with a slight limitation of extension'(^^^^)), is
expected in patients with either an acutely inflamed
joint based on the presence of classic inflammatory signs
(arthritis) or a diagnosis of degenerative changes of the
joint (arthrosis). We explored the ratio of loss of extension to loss of flexion during PROM in patients with and
without e ~ l d e n c eof arthritis or arthrosis. We hypothesized that patients with evidence of arthritis or arthrosis
will tend to demonstrate a capsular pattern of PROM
restriction (ie, a great loss of flexion, with a slight loss of
extension). Based on an examination of the data, we
selected a definition of a capsular pattern that maximizes the discrimination between patients with and
without evidence of arthritis and arthrosis. After this
definition was determined from the data, we performed
statistical tests to determine whether there was an association between arthritis or arthrosis and the presence of
a capsular pattern of PROM restriction.
A s e c o n d a ~purpose of the study was to evaluate the
relationship between the inflammatory status of the joint
and the PRS, as well as the chronicity (ie, time from
injury or surgery) of the subjects' condition and the PRS.
We hypothesized that the PRS would be associated with
the inflammatory status of the joint, but would not be
associated with the chronicity of the subjects' condition.
Method
Inclusion Criteria
Subjects eligible for this study were individuals referred
to physical therapy centers for treatment of unilateral
knee dysfunction. The subjects were questioned regarding prior injuries to the contralateral knee. Any patient
reporting previous injuries or surgeries involving the
contralateral knee were excluded. No patient was
excluded based on diagnosis, chronicity, or surgical
status of the involved knee. The diagnosis made by the
referring physician was noted by the subjects' physical
therapist. All subjects were questioned by their physical
therapist whether radiographs of the knee were taken.
All data were collected during the subjects' initial evaluation prior to beginning physical therapy.
Physical Therapy . Volume 7 8 . Number 10 . October 1998
Procedure
Data for this study were collected in 15 centers by 33
participating therapists. Each therapist was proklded
with instructions for performing the measurement of
PROM and tests of inflammation. Operational definitions of the PRS were problded, based on the descriptions given by C y r i a ~ . ' ( p NO
~ ~ )additional training was
provided to the therapists. The subjects' diagnosis,
involved knee, surgical history, history of present injury,
the patient-reported results of any diagnostic imaging
studies performed, and date of onset or the date of
surgery were recorded.
Range-of-motion measurements. Extension PROM of
the knee joint was measured with the subject positioned
supine. The heel was elevated on a bolster to allow for
full hyperextension, if present. Flexion PROM was measured rvith the subject positioned supine and the hip
initially in extension. Measurements of PROM for flexion and extension were recorded for each knee. Difference scores for flexion and extension were calculated by
subtracting the measurement of the uninvolved knee
from the measurement of the involved knee. The ratio of
extension loss to flexion loss was calculated by dividing
the difference score for extension by the difference
score for flexion. Subjects with a difference score for
flexion of zero were considered to have a ratio of zero to
avoid undefined values in the data analysis. Subjects with
a difference score for extension of zero would also have
a ratio of zero. If the involved knee had greater motion
than the uninvolved knee in either flexion or extension,
the ratio of the difference scores had a negative value.
Assessment of the pain-resistance sequence. The PRS
was assessed during the measurement of flexion PROM.
The examiner first asked each subject to rate his or her
baseline level of pain from 0 to 10, rvith 0 representing
no pain and 10 representing the worst pain imaginable,
with the knee relaxed in an extended position. The
examiner then moved the knee passively into flexion,
and the subject was asked when the pain increased above
the baseline level during this motion. If the limitation of
PROM for flexion was encountered before the subject
reported an increase in pain, mild pressure was applied
over the subject's anterior tibia to move the knee farther
into flexion. The subject was again asked whether the
pain had increased above the baseline level. The examiner recorded whether the point of increased pain
occurred before, during, or after the limitation of passive motion was encountered.
The cardinal signs of
inflammation are pain, redness, warmth, and swelling.
All subjects in this study had some degree of pain;
therefore, other methods were used to assess for the
presence of the 3 inflammatory signs other than pain.l
Assessment of inflammatory status.
Physical Therapy . Volume 7 8 . Number 10 . October 1998
These methods were (1) visual inspection for redness,
(2) palpatory assessment for warmth, (3) a patellar tap
test, and (4) a fluctuation test. Each of these tests was
judged by the examiner as either positive or negative for
the presence of signs of inflammation.
The examiner first visually examined the involved knee
for the presence of redness as compared with the
uninvolved knee. The examiner then palpated the anterior aspect of the involved knee for the presence of
increased temperature as compared with the uninvolved
knee. The patellar tap and the fluctuation test were
described by Cyriax as tests for the presence of swelling
~ ~ ~patellar
'
tap is performed
in the knee j o i n t . l ( ~ The
with the subject positioned supine. The examiner
presses on the suprapatellar pouch, then taps on the
patella. If swelling is present, the patella will, in theory,
be lifted off the femur and can be tapped down onto the
femur. If swelling is not present, the patella should
remain in contact with the femur. The fluctuation test is
also performed with the subject positioned supine. The
examiner places the thumb and finger of one hand
around the patella. The other hand is used to push any
fluid from the suprapatellar pouch. If swelling is present,
the finger and thumb should be pushed apart. If swelling
is not present, no movement is supposed occur. We
anticipated that the reliability of judgments made with
these tests indikidually could be questionable. MTetherefore considered the joint to be inflamed when 2 or more
of the tests were judged to be positive for signs of
inflammation. This was done to avoid the classification
of a joint as inflamed based o n a single, potentially
unreliable judgment.
Categorization of the joint. An inflamed joint was considered to have "arthritis," as the term was used by
C y r i a ~ . l ( p Subjects
~~)
with 2 or more tests that were
positive for signs of inflammation, therefore, were
defined as having arthritis. Subjects whose referring
physician diagnosed them as having unilateral knee
osteoarthritis, as confirmed by radiographs, were
defined as having arthrosis. These 2 groups of subjects
(subjects with arthritis and subjects with arthrosis)
should have a capsular pattern, according to Cyriax.'(pi7)
All other subjects (subjects without evidence of arthritis
or arthrosis) would not be expected, according to
Cyriax, to have a capsular pattern.
Interrater reliability. Reliability is a precursor to validity.
Interrater reliability of the 4 inflammation tests, the
categorization of a subject's knee as inflamed or noninflamed, the PRS, the measurements of knee flexion and
extension during PROM, and the ratio of extension loss
to flexion loss, therefore, was determined on a subset of
35 subjects. These subjects were examined by their
treating therapist and then examined by one of the
Fritz et al
. 1049
Table 1.
lnterrater Reliability for 35 Subjects for Judgments on
Categorical Variables
of extension loss to flexion loss were determined by
examining the histogram and selecting cutoff points that
appeared
to maximize the differentiation of subjects
-categorized as with or without arthritis or arthrosis of
the knee.
Variable
Kappa
Percentage of
Agreement
Fluctuation test
Patellar tap test
Palpation for warmth
Visual inspection for redness
categorization of the
inflammatory status of the ioint
Pain-resistance sequence
.37"
.2 1 "
.66"
.2 1 "
.71
.7 1
.83
.85
selecting the cutoff points, subjects were divided into 4
mutually exclusive groups:
.76"
.2Bb
.89
.74
1. True positive: subjects with evidence of arthritis or
arthrosis with a capsular pattern.
"Coefficient represenh use of the kappa statistic. '
"Coefficient represenh use of the weighled kappa statistic."
researchers (JMF) during the same session, without any
treatment or further evaluation in the intenrening
period. The results of the first examination were not
available to the second therapist. Eight different therapists at 2 centers participated in the collection of reliahilitv data. No additional instructions or training were
provided to these therapists.
Interrater reliability for the 4 inflammation tests
(warmth, redness, patellar tap, and fluctuation), the
PRS, and the categorization of the involved knee as
inflamed or not inflamed was analyzed with Cohen's
kappa coeficients.5 Interrater reliability of the PRS
measurements was analyzed using a weighted kappa with
symmetrical kappa weights."nterrater
reliability for
measurements of PROM and for the ratio of extension
loss to flexion loss was analyzed using intraclass correlation coefficients (ICC[2,1]) .'
Interrater reliability values for categorical variables are
given in Table 1. Kappa coefficients for the inflammatory tests ranged from .21 to .66. Categorization of the
joint as inflamed or noninflamed based o n the presence
of 2 or more inflammatory signs showed substantial
clinical agreement ( ~ = . 7 6 )Judgments
.~
of the PRS
showed a weighted kappa of .28. Interrater reliability
values and standard errors of measurement for the
PROM measurements are presented in Table 2. The
mean ratio of PROM loss for these 35 subjects was 0.3
(SEM=0.16, ICC=.85). Intraclass correlation coefficients for PROM measures ranged from .72 to .97.
Data Analysis
We followed a step-by-step process outlined by Sackett
et alYfor interpreting clinical test results.
Histogram construction. The first step was construction
of a histogram showing the number of subjects with and
without the target disorder (arthritis or arthrosis), given
a certain value of the test result (ratio of extension loss
to flexion loss). T h e upper and lower limits of the ratio
1050 . Fritz et al
Receiver operating characteristic curve construction. After
2. False positive: subjects without evidence of arthritis o r
arthrosis with a capsular pattern.
3. False negative: subjects with evidence of arthritis or
arthrosis with a noncapsular pattern.
4. True negative: subjects uithout evidence of arthritis
or arthrosis with a noncapsular pattern.
The number of subjects in each group was displayed in
a contingency table (Fig. I ) , allowing for the calculation
of sensitivity and specificity values. Sensitivity (true-positive rate) describes the test's ability to detect the target
disorder when present. Specificity (true-negative rate)
describes the test's ability to identi5 the absence of the
target disorder when not present."
The sensitivity and specificity values for given levels of
the test result are used to validate the choice of cutoff
points by calculating sensitivity and specificity values for
different levels of the test result and by graphing the
pairs of values as a receiver operating characteristic
(ROC) curve.1° An ROC curve has the sensitivity values
expressed as a proportion along the Y axis and the 1 specificity values expressed as a proportion on the X
axis. A perfect test (100% specific and 100% sensitive)
would be located in the upper left-hand corner of the
graph. The point on the ROC cunre closest to the upper
left-hand corner, therefore, is considered the "best"
cutoff point for the test r e ~ u l tWe
. ~ graphed the sensitivity and specificity values as a ROC cunre for the ratios of
ROM loss at interval widths of 0.10, and we used the ratio
closest to the upper left-hand corner as the cutoff point
for defining a capsular pattern.
Contingency table construction. Using this cutoff point,
a contingency table was constructed, sensitivity and
specificity values were calculated, and a positive likelihood ratio (sensitivity/ 1-specificity) was determined.
Likelihood ratios are becoming increasingly popular for
characterizing the value of test r e ~ u l t s . l l -The
~ ~ positive
likelihood ratio describes the odds that a given test result
would be expected in a subject with (as opposed to
Physical Therapy . Volume 7 8 . Number 10 . October 1998
Table 2.
Reliability Coefficients for
35 Subjects for Continuous Variables
Variable
X
SD
Range
lCCb
Flexion (~~ninvolved
side)
Flexion (involved side)
Extension (uninvolved side)
Extension (involved side)
Ratio (extension loss/flexion loss)
138"
118"
6.8"
20.6"
3.l o
6.9"
0.4
95"-155"
46"-151 "
-9"-15"
-34"-15"
-3.0-6.6
.80
.97
.72
.94
.85
4"
0"
0.3
SEM~
"l~itraclasscorrelation coefficient calculated using equatiorl ( 2 , l ) fro111Shrout and Fleiss.'
"Standard elrror of rneasurenle~itcalculated as SD(1 - ICC)1'2.
Figure 1.
Example 01: general format of a 2 x 2 table for the description of the
diagnostic value of a test result, with formulas for the calculation of
sensitivity, specificity, and predictive values.
without) the target d i s ~ r d e rA. ~positive likelihood ratio
of 1 indicates a test that is of no value because it does not
change the odds of finding the target disorder. Ratios of
greater than 1 indicate a test that increases the likelihood of correctly classifying a subject based on the test
result, and ratios of less than 1 indicate a test in which
more subjects will be classified incorrectly after the test
result is known."l1.l4 Confidence intervals were determined for the sensitivity, specificity, and likelihood ratio
according to the method of Simel et al."
Chi-square tests of association. Chi-square tests of asso-
ciation were used to test the hypotheses concerning the
association between (1) subjects with arthrosis or arthritis and the presence of a capsular pattern of PROM
restriction, (2) the inflammatory status of the joint and
the PRS, and (3) the chronicity of the condition and the
PRS. The: value of a chi-square test statistic can be greatly
influenced by large sample sizes.l5 We therefore set the
significance level at .O1 for each of the 3 chi-square tests.
2 / [ ~ (-qI)],
Cramer contingency coefficients ( v ' = ~
where q is either the number of rows or the number of
columns, whichever is smaller) were calculated for each
chi-square test as a measure of the degree of association
between row and column data in each contingency
table.'" Chi-square analyzes were conducted using the
SPSS statistical package.*
Results
Data were collected on 152 subjects. Table 3 shows the
descriptive subject data. The average age of the sample
SPSS Inc, 444 N Michigar1 Ave, Chicago, 11. 6061 1.
Physical Therapy . Volume
78 . Number 10 . October 1998
was 40.0 years (SD= 15.9, range= 13-82). The right side
was involved in 71 subjects (46.7%),and the left side was
involved in 81 subjects (53.3%). Seventy-seven subjects
(50.7%) had undergone knee surgery, and 75 subjects
(49.3%) had not undergone knee surgery. Chronicity
was divided into 3 categories: acute (<2 weeks from
onset of pain or surgery), subacute (2-6 weeks
from onset of pain or surgery), and chronic (>6 weeks
from onset of pain or surgery). Forty-five subjects
(29.6%) were classified as acute, 56 subjects (36.8%)
were classified as subacute, and 51 subjects (33.6%) were
classified as chronic.
Descriptive statistics for the 4 inflammatory tests and the
categorization of the inflammatory status of the involved
knee are also given in Table 3. Based on the definition of
inflammatory status used in this study (2 or more
positive tests), 71 knees (46.7%) were considered
inflamed, and 81 knees (53.3%) were considered
noninflamed.
A capsular pattern of restriction was expected for subjects categorized as having inflamed knees (arthritis) or
diagnosed with arthrosis. Seventy-one subjects were categorized as having an inflamed joint, and 12 subjects
were diagnosed with arthrosis by radiographs. Four of
these 12 subjects were also categorized as having an
inflamed joint. Thus, 79 subjects were categorized as
having arthritis or arthrosis, and 73 subjects were categorized as not having arthritis or arthrosis.
Histogram Construction
The histogram constructed showing the number of
subjects with and without arthritis or arthrosis, given
different levels of the ratio of PROM loss, is presented in
Figure 2. According to Cyriax's definition of a capsular
pattern, subjects with a negative ratio of extension loss to
flexion loss, indicating greater motion of the involved
knee, or a ratio of zero, indicating equal motion in
flexion or extension, would be considered to have a
noncapsular pattern and would not be expected to have
arthritis or arthrosis. Negative ratios or a ratio of zero,
therefore, had to fall outside the range of ratios of
PROM loss defining a capsular pattern. It was clear from
Fritz et al
. 105 1
Table 3.
Descriptive Data of Subjects"
Capsular Noncapsular
PaHern
Sample Paitern
(N=152) (n=76)
(n=76)
Total
Receiver Operating Characteristic Curve Construction
Ag_e (Y)
X
SD
Range
40.0
15.9
13-82
41.84
16.6
21-82
38.0
14.5
13-77
Involved side
Right
Left
71
81
37
39
34
42
41
17
20
15
21
2
15
12
12
5
10
4
10
2
8
11
25
19
4
6
12
7
19
7
56
71
25
31
39
6
25
32
19
Diagnosis
Arthroscopic
surgery
ACL reconstruction
Patellofemoral
dysfunction
Osteoarthritis
ACL deficiency
Internal
derangement
Other (nonsurgical]
Other (postsurgical)
Pain-resistance
sequence
Before
During
After
Chronicity
Acute (<2 wk)
Subacute (2-6 wk)
Chronic (>6 wk)
Inflammatory test
Warmth
Redness
Patellar tap
Fluctuation
Categorization of
joint status
Inflamed
Noninflamed
45
56
51
30
20
26
15
36
25
82
27
51
85
50
21
35
57
32
6
16
28
The ROC curve constructed from the sensitivity and
specificity values for each 0.10 interval of the ratio of
PROM loss is shown in Figure 3. The lower bound was
maintained at 0.03 because this value clearly maximized
the discrimination between knees with and without
arthritis or arthrosis. This lower bound, in our opinion,
also was consistent with Cyriax's definition of a capsular
pattern because ratios of zero indicate no loss of either
flexion or extension during PROM and negative ratio
values indicate an excess of flexion or extension during
PROM on the involved side. The ratio closest to the
upper left-hand corner of the graph coincided with the
upper limit value (0.50) determined from the histogram.
The capsular pattern of the knee, therefore, was defined
as a ratio of extension loss to flexion loss between 0.03
and 0.50. Descriptive statistics of the subjects with a
capsular or noncapsular pattern of PROM restriction are
given in Table 3.
Contingency Table Construction
The contingency table constructed using this definition
of a capsular pattern (ie, 0.03-0.50) is shown in Table 4.
Sensitivity was calculated as 74.7%, and specificity was
calculated as 76.7%, with a likelihood ratio of 3.20.
Based on these results, a subject with a capsular pattern
was 3.2 times more likely than not to have evidence of
arthritis or arthrosis of the knee.
Chi-square Tests of Association
71
81
59
17
12
64
Pain-resistance sequence is based on the nlrasuremcnt of flexion range of
rnotion. A capsular parrern xas defined ;B a ratio of extension loss to flexion
loss beween the \alurb of 0.03 and 0.50. Categorization ofjoint status is based
on the presence o f 2 or more inflammatory tesrs. .iCL=anrerior cmciate
li~?!nent.
"
the histogram that small positive ratios were associated
with a greater likelihood of arthritis or arthrosis. Small
posithe ratios indicate a much higher loss of flexion
than extension and, therefore, are consistent with Cyriax's definition. The smallest positive ratio found in any
subject was 0.03. We therefore selected a ratio of 0.03 as
the lower limit defining a capsular pattern. The choice
of an upper limit was not as clear from the histogram. X
ratio of 0.50 (flexion loss twice as great as extension loss)
was selected. From the histogram, it appeared that
defining a capsular pattern as a ratio of extension loss to
flexion loss between 0.03 and 0.50 maximized discrimi1052 . Fritz et al
nation behveen subjects with and without evidence of
arthritis or arthrosis. We believe that these limits are also
consistent with Cyriax's definition of a capsular pattern
(great limitation of flexion, with a slight limitation of
extension).
The hypothesis of an association between arthritis or
arthrosis and the presence of a capsular pattern was
confirmed (X2=10.09, P<.000001, v'= .264). The pattern of PROM restriction explained 26.4% of the ~rariability in the presence or absence of arthritis or arthrosis
(Tab. 4).
The associations between the PRS and chronicity and
between the PRS and inflammatory status are shown in
Table 5. The hypothesis of no association between the
PRS and chronicity was rejected (X 2 = 16.10, P= .0029,
v 2 =.053). The hypothesis of an association between the
PRS and the inflammatory status of the joint was confirmed (X"18.74, P< .00001, v'=. 123). The chronicity
and inflammatory status explained 5.3% and 12.3% of
the variability in the PRS, respectively.
Discussion
The results of our study provide evidence for the existence of a capsular pattern as we have defined i t and for
Physical Therapy . Volume 7 8 . Number 10 . October 1998
Figure 2.
Histogram showing the number of subjects with and without evidence of arthritis or arthrosis at different levels of the ratio of extension loss to flexion
loss for passive range of motion. Based on this histogram, the best definition of a capsular pattern appears to be between the ratios of 0.03 and 0.50
because these values encompassed the majority of subjects with arthritis or arthrosis (no subjects had ratios between the values of 0.00 and 0.03).
its use in identifying arthritis and arthrosis in patients
with unilateral knee dysfunction. Our data do not necessarily support the existence of a capsular pattern as
defined in any other way. The definition of a capsular
pattern that best differentiated between subjects with
and without arthritis or arthrosis appears to be a ratio of
extension loss to flexion loss between 0.03 and 0.50. We
believe that this definition appears to be consistent with
Cyriax's original description of the capsular pattern of
the knee as a "gross limitation of flexion, with slight
limitation of extension."1 ( P 80) Previous research examining the capsular pattern of the knee was unable to
identify a proportional definition of a capsular pattern
in a group of patients with osteoarthrosis of the knee. 3
We believe that our methods, including the subject
population studied, and the method of determining
cutoff points defining a capsular pattern allowed for this
proportional definition to emerge. We did not use
Cyriax's original formulation of the pattern or those
definitions suggested by other authors, but rather we
Physical Therapy . Volume 78 . Number 10 . October 1998
developed our own formulation based on observed
ratios of motion loss.
In our study, we expanded the patient population
beyond those with arthrosis to include patients with
more "arthritic" conditions (implying an inflammatory
process) as well as patients without evidence of arthritis
or arthrosis. A study attempting to examine the usefulness of a diagnostic test should include a spectrum of
subjects, including those with and without the disorder
that the researchers are attempting to identify.9 Without
the inclusion of subjects without the target disorder, it is
not possible to estimate the specificity of a test, nor is it
possible to calculate likelihood ratios. It is difficult to
ascertain the diagnostic usefulness of a test without these
values.
As mentioned earlier, Cyriax stated that the capsular
pattern of the knee joint is a "gross limitation of flexion,
with slight limitation of extension." 1 ( P 80) He also pro-
Fritz et al . 1053
"a proportional definition of a capsular
pattern should be abandoned, but the
concept of a pattern of ROM loss may
be useful."Vhe authors also pointed
out that had the strict proportional
definition of a capsular pattern not
been used, 96% of their subjects with
arthrosis of the knee would have had a
capsular at tern.^
1.00 0.9 -
We believe that therapists evaluating
patients with knee joint dysfunction
tend to interpret a capsular pattern in
terms of a pattern of PROM loss, and
not a strict proportional definition
based on one example provided by
I
I
I
I
Cyriax, but we have no evidence for this
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00
assumption. We therefore used a different approach to determining the cutoff
1 Specificity
points defining a capsular pattern in
patients
with knee joint dysfunction.
Figure 3.
Receiver operating characteristic curve constructed from the sensitivity and specificity values at We chose not to use the example p r e
different intervals of the ratio of extension loss to flexion loss. The interval of 0.03 to 0.50
vided by Cyriax, but instead focused on
produced the point nearest the upper left-hand corner and, therefore, represents the best
the definition of a capsular pattern as a
interval of ratios defining a capsular pattern of the knee.
great limitation in flexion and a slight
limitation in extension. We sought to
analyze the data in a manner that
Table 4.
allowed the boundaries defining a capsular pattern to be
Relationship Between the Presence of Arthritis or Arthrosis and a
refined prior to any statistical analysis.
-
Capsular Pattern of Restriction of Range of Motion0
Capsular pattern present
Noncapsular pattern present
Arthritis or
Arthrosis
Present
Arthritis or
Arthrosis
Not Present
20
56
" A capsular pattern was defined as a ratio of extension loss tu flexion loss
henveen the values of 0.03 and 0.50. Values in parentheses represent the 95%
confidence intenal." Signiiicanre set at P<.01. V2=Cramer contingency
roefficienr.
vided an example: "5 or 10 degrees limitation of extension corresponds with 60 to 90 degrees limitation of
f l e x i ~ n . " ~ ( pIn~ al ~previous
~j
study examining the diagnostic utility of a capsular pattern of the knee, Hayes
et al' adopted a definition of a capsular pattern based on
the values provided in this example. Based on this
definition, which corresponded to a ratio of extension
loss to flexion loss between the values of 0.06 and 0.1 1 ,
the authors found vely few subjects with arthrosis of the
knee exhibited a capsular pattern.They concluded that
1054 . Fritz et al
We first used a histogram and a ROC curve analysis to
determine the best cutoff points for defining a capsular
pattern. Using this approach, a ratio of extension loss to
flexion loss was identified, with sensitivity and specificity
values approaching or exceeding 75% and with a positive likelihood ratio of 3.2. These values provide some
evidence for the diagnostic usefulness of distinguishing
between patients with and without arthritis or arthrosis.
The positive likelihood ratio value found in this study
means that a patient exhibiting a capsular pattern,
defined as a ratio of extension loss to flexion loss
between 0.03 and 0.50, is 3.2 times more likely than not
to have arthritis or arthrosis of the knee. Only after these
cutoff points were determined was a chi-square test of
association performed. Although the results of this chisquare analysis were significant, we believe that the
sensitivity, specificity, and positive likelihood ratio values
are more clinically meaningful and do more to attest to
the diagnostic usefulness of a capsular pattern of the
knee.
The PRS is proposed to be a test of the acuity of ajoint's
inflammatory status and a guide to the vigor with which
treatment should p r o ~ e e d . ~Hayes
( ~ ~ et
~ jal' used c h r e
nicity (days from onset of inflammation) as a measure of
acuity and found no correlation with the PRS. Other
Physical Therapy . Volume 78 . Number 10 . October 1998
Table 5.
Association Between the Pain-Resistance Sequence and Chronicity
and Between the Pain-Resistance Sequence and the Inflammatory
Status of the Jointo
Pain
Before
Resistance
Chronicity versus
pain-resistance
sequence
Acute
Subacute
Chronic
Pain With
Resistance
Pain After
Resistance
27
17
12
14
30
27
4
9
12
38
18
28
43
5
20
x2=16.10
P=l3029
V2=.053
lnflammatory
status versus
pain-resistance
sequence
Inflamed
Not inflamed
2 = 18.74
P < .oooo 1
V2=.123
was improved by additional training (including providing adequate operational definitions). The inflammation tests and ROM measures were not specific to this
study. The inflammation tests were done as we believe
Cyriax described them. What was specific to this stiidy
were the definitions of an inflamed joint versus a noninflamed joint and of a capsular pattern versus a noncapsular pattern.
Several topics for future investigation are suggested by
our study. We recognize the need to replicate the results
of this study regarding the capsular pattern of the knee
o n other data sets and the possibility that this replication
may result in further refinement of the definitions used
in our study. Furthermore, the validity of measurements
obtained for the other passive motion components of
Cyriax's selective tissue tension scheme needs to be
addressed at the knee and for otherjoints. The reliability
and validity of measurements obtained for the PRS and
of judgments of end-feel with passive motion need
further examination. The best definitions of capsiilar
patterns at other joints need to be explored.
We acknowledge several potential limitations of our
study. The measurement of PROM and the calculation
of ratios involve a degree of measurement error. Even
researcher^^^.^* have suggested that, given the cycle of
though we found acceptable ICC values for these meaexacerbation and remission common in musculoskeletal
surements (ICC=.'72-.9'7), the standard errors of meainjuries, acuity might be more accurately judged by a
surement demonstrate a need for cautious interpretapatient's signs and symptoms than by time from onset of
tion of the precision of these measurements. We
inflammation. We compared both chronicity and inflamrecognize that the error inherent in the measurements
matory status with the results of the PRS. Although both
used to calculate ratios of PROM loss make a strict
chi-square statistics reached significance, the inflammainterpretation of these ratios unwarranted. In addition,
toly status of the joint explained more than twice the
not all patients had undergone diagnostic testing; therevariability in the PRS than did chronicity (12.3% versus
fore, some patients may have had undiagnosed arthrosis
5.3%). Similar to Hayes et al,"owever,
we found only
and could have been misclassified. Furthermore,
fair clinical agreement for the PRS (weighted ~ = . 2 8 ) , because we relied o n patient-reported results of imaging
making any conclusions regarding the validity of the PRS
studies, errors in recall o r understanding on the part of
suspect.
the patient also may have resulted in misclassification of
some patients.
We believe that this finding points to a need for further
work to refine clinical judgments of the acuity of a
We identified subjects with unilateral knee dysfunction
patient's condition. One option is the development of a
by questioning the individual regarding prior involvecomposite measure of several examination procedures
ment of the other knee. It is possible that some subjects
as a basis for the judgment of acuity. Other researchers1"
may not have recalled a prior injury or may not have
have improved reliability when a composite of tests was
believed the injury to be serious enough to report.
used instead of a single test. In our study, we were able to
Additionally, the use of the presence of 2 out of 4
improve the reliability of categorization of a joint as
inflammatory signs as a method for categorizing a joint
inflamed or noninflamed to a level of substantial agreeas inflamed has not been reported by other researchers
ment ( ~ = . 7 6 )whereas
,
the individual inflammatory tests
or subjected to studies of concurrent validity with other
demonstrated lower levels of clinical agreement ( K =
measures of inflammatory status. MTe chose this tech.21-.66). Another method for improving reliability is
nique to take advantage of the improved reliability of a
provision of additional training for clinicians and
composite measure as opposed to an individual test to
improvement of the operational definitions of terminoldetermine inflammatory status. The use of the uninogy used in judgment of the PRS. Although we recognize
volved limb limits the generalizability of our results to
the limitations of this approach with respect to generalpatients with unilateral knee dysfunction. We recognize
izability, other investigators2" have found that reliability
"Significance set at P <.Ill. VY=cramrrcontingrnc). coefficient
Physical Therapy
. Volume 78 . Number 10 . October 1998
Fritz et al . 1055
that arbitrary "normal" values may need to be considered in patients with bilateral involvement.
4 Reed B, Zarro VJ. Inflammation and repair and the use of thermal
agents. In: Michlovitz SL, ed. Thermal Agents in Rehabilitation. 2nd ed.
Philadelphia, Pa: FA Davis Co; 1990:3-17.
In addition, in studies of the accuracy of diagnostic tests
that use a comparison with a "gold standard," it is
recommended that the individual assessing the gold
standard (arthritis or arthrosis in our study) be blinded
to the diagnostic test results (PROM loss)." In our study,
the same clinician performed both tests of inflammation
used in determining the gold standard and the PROM
measurements. We used this method because it was not
clinically feasible to have different therapists assess these
2 variables independently. The clinicians, however, were
not aware that a joint would be classified as inflamed
based on 2 or more positive findings, nor did they know
the ratios of PROM loss that would eventually be selected
as cutoff points for determining a capsular pattern.
5 Cohen J. A coefficient of agreement for nominal scales. Educational
and Pr~chologicalMeasurement. 1960;20:37-46.
Conclusion
This study examined 2 elements of the PROM portion of
the selective tissue tension scheme described by Cyriax:
the PRS and a capsular pattern of motion restriction.
The PRS measurements were not found to be reliable.
Examination of the capsular pattern began by examining the ratios of extension ROM loss to flexion ROM loss
in those subjects who either were or were not expected
to have a capsular pattern based on Cyriax's definitions.
Cutoff points for the ratios of ROM loss defining a
capsular pattern were determined to be 0.03 and 0.50 by
examining a histogram and an ROC curve constructed
from these data. Using this definition, which differs in
detail but not in concept from that originally put forward by Cyriax, a capsular pattern was found to be 3.2
times more likely to be present in patients with either
arthritis or arthrosis of the knee joint. Although the
precision of ROM measurements taken with a goniometer make a strict interpretation of the cutoff points
determined in this study unwarranted, the results provide evidence for a proportional definition of a capsular
pattern of the knee as a great limitation of flexion ROM
with a slight limitation of extension ROM.
6 Cohen J. Weighted kappa: nominal scale agreement with provision
for scaled disagreement or partial credit. Psyrhol Bull. 1968;70:213-220.
7 Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rater
reliability. Pssrhol Bull. 1979;86:420-428.
8 Landis JR, Koch
The measurement of obsemer agreement for
categorical data. Biometlics. 1977;33:139-1 74.
9 Sackett DL, Haynes RB, Guyatt GH, Tugwell P. Clinical Epidemiology
A B a ~ i cScience Jor Clinicccl Medicine. 2nd ed. Boston, Mass: Little, Brown
and Co Inc; 1992:69-152.
10 Hanley JA, McNeil BJ. The meaning and use of the area under a
receiver operating characteristic (ROC) cume. Radioloa. 1982;143:
29-36.
11 Dujardin B, Van den Ende J , Van Compel A, et al. Likelihood ratios:
a real improvement for clinical decision making? Eur J Epidemiol.
1994;10:29-36.
12 Simel DL, Samba GP, Matchar DB. Likelihood ratios with confidence: sample size estimation for diagnostic test studies. J Clin Epidemiol. 1991;44:763-770.
13 Lacher DA. Predictive value derived from likelihood ratios: a
superior technique to interpret quantitative laboratory results. Am J
Clin Pathol. 1987;87:673- 676.
14 Simel DL, Feussner JR, DeLong ER, Matchar DB. Intermediate,
indeterminate, and uninterpretable diagnostic test results. Mrd Derzs
Making. 1987;7:107-114.
15 Glass GV, Hopkins KD. Statistiral Mrthods in Psyrholoa and Eduration.
3rd ed. Boston, Mass: Allyn and Bacon; 1996333-338.
16 Conover U'J. Prartiral Nonparnmrtnr Stntirtirs. 2nd ed. New York, NY:
John Wiley & Sons Inc; 1980:178-184.
17 Delitto A, Erhard RE, Bowling RM'. A treatment-based classification
approach to low back syndrome: identifying and stagmg patients for
consemative treatment. Phys Thm. 1995;75:470-485.
18 Von Korff M, Deyo Rh,Cherkin D, Barlow W. Back pain in primary
care: outcomes at 1 year. Spit~r.1993;18:855-862.
19 Cibulka MT, Delitto A, Koldehoff RM. Changes in innominate tilt
after manipulation of the sacroiliac joint in patients with low back pain:
an experimental stiidy. Phys Thm. 1988;68:1359-1 363.
20 Diamond ,JE, Mueller MJ, Delitto A, Sinacore DR. Reliability of a
diabetic foot evaluation. Phys Thm. 1989;69:797-802.
References
1 Cyriax J. Tpxthook oJ Orthopardir iMedicir~e,Volume I : Diagnosis of Soft
Tissue Lpsions. 6th ed. London, England: BailliPre Tindall; 1982.
21 Sackett DL, Richardson WS, Rosenberg UT,Haynes RB. EvidenreBased ~M~dzrinr:
How to Prartirc and T ~ a r EBM.
h
New York, NY: Churchill
Livingstone Inc; 1997:81-84.
2 Pellecchia GL, Paolino J, Connell J. Intertester reliability of the
(:yriax evaluation in assessing patients with shoulder pain. J Orihop
Sports Phys Thm. 1996;23:34-38.
3 Hayes KM', Petersen C, FalconerJ. An examination of Cyiax's passive
motion tests 5~1thpatients ha\1ng osteoarthritis of the knee. Phys Thm.
1994;74:697-707.
1056 . Fritz et a1
Physical Therapy . Volume 78 . Number 10 . October 1998