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FAMILY PHYSICIAN 279
asymmetric joint cartilage loss, subchon-dral sclerosis
(increased bone density),marginal osteophytes and subchondralcysts
is the same in younger and olderadults.1 Primary osteoarthritis is
themost common form and is usually seenin weight-bearing joints
that have under-gone abnormal stresses (e.g., from obe-sity or
overuse).13-16 The precise etiologyof osteoarthritis is unknown,
but bio-chemical and biomechanical factors arelikely to be
important in the etiology andpathogenesis.1 Biomechanical
factorsassociated with osteoarthritis includeobesity, muscle
weakness and neurologicdysfunction. In primary osteoarthritis,the
common sites of involvement in-clude the hands, hips, knees and
feet13,17
(Figure 1). Secondary osteoarthritis is acomplication of other
arthropathies orsecondary to trauma. Gout, rheumatoidarthritis and
calcium pyrophosphatedeposition disease are correlated with
theonset of secondary osteoarthritis.
Clinical ManifestationsOsteoarthritis is primarily assessed
through a history and physical examina-tion. The cardinal
symptom of osteo-arthritis is pain that worsens during
Worldwide, osteoar-thritis is the mostcommon form ofarthritis.1
It is amongthe most prevalent
and disabling chronic conditions in theUnited States.2 The
prevalence increaseswith age, and by the age of 65, approxi-mately
80 percent of the U.S. population isaffected.3-5 The functional
impairmentssecondary to osteoarthritis also occurmore frequently in
older adults. Pain andlimitation of motion restrict the
indepen-dence of older adults by impairing theirperformance of
activities of daily living.6,7
As a result, dependence is especially com-mon for ambulation,
stair climbing andother lower-extremity functions.8
Costs directly attributable to osteo-arthritis are considerable
in the UnitedStates, with work loss accounting for morethan one
half of the estimated annualexpense of $155 billion (in 1994
dollars).9
Another major expense is the number ofjoint arthroplasties
performed in patientsin the advanced stage of the disease.10-12
Etiology and Risk FactorsAlthough osteoarthritis is
especially
common in older adults, its pathology of
Osteoarthritis is one of the most prevalent and disabling
chronic conditions affecting olderadults and a significant public
health problem among adults of working age. As the bulkof the U.S.
population ages, the prevalence of osteoarthritis is expected to
rise. Althoughthe incidence of osteoarthritis increases with age,
the condition is not a normal part of theaging process. More severe
symptoms tend to occur in the radiographically moreadvanced stage
of the disease; however, considerable discrepancy may exist
betweensymptoms and the radiographic stage. Roentgenograms of
involved joints may be usefulin confirming the diagnosis of
osteoarthritis, assessing the severity of the disease, reas-suring
the patient and excluding other pathologic conditions. The
diagnosis ofosteoarthritis is based primarily on the history and
physical examination, but radiographicfindings, including
asymmetric joint space narrowing, subchondral sclerosis,
osteophyteformation, subluxation and distribution patterns of
osteoarthritic changes, can be helpfulwhen the diagnosis is in
question. (Am Fam Physician 2001;64:279-86.)
Radiographic Assessment of OsteoarthritisDANIEL L. SWAGERTY,
JR., M.D., M.P.H., and DEBORAH HELLINGER, D.O.University of Kansas
Medical Center, Kansas City, Kansas
COVER ARTICLERADIOLOGIC DECISION-MAKING
Coordinators of this series areMark Meyer, M.D., at the
Uni-versity of Kansas School ofMedicine, Kansas City, Kan.,
andWalter Forred, M.D., Universityof Missouri-Kansas City Schoolof
Medicine, Kansas City, Mo.
The editors of AFP welcome thesubmission of manuscripts forthe
Radiologic Decision-Makingseries. Send submissions to JaySiwek,
M.D., following theguidelines provided in Informa-tion for
Authors.
ILLU
STR
ATI
ON
BY
SC
OTT
S. B
OD
ELL
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activity and improves with rest. Instability ofjoints is a
common finding, especially of theknees and first carpometacarpal
joints. Earlymorning stiffness is common and characteris-tically
lasts one hour or more, depending onseverity. Stiffness may occur
following periodsof inactivity. Musculoskeletal examinationmay
reveal swelling, deformities, bony over-growth (referred to as
Heberdens nodes wheninvolving the distal interphalangeal joints
andBouchards nodes when involving the proxi-mal interphalangeal
joints of the hands),crepitus and limitation of motion.
Musclespasm, and tendon and capsular contracturesalso may be
observed, depending on the siteand duration of involvement.
Pain caused by osteoarthritis may develop inany part of the
involved joint or tissue. Typi-cally, pain progresses gradually
over time andincreases with weight bearing. A patient withprimary
osteoarthritis seldom has any attribut-able systemic symptoms
(e.g., fatigue or gener-alized weakness). The progression of
symp-toms in patients with osteoarthritis is fairlyconsistent. Mild
discomfort first occurs in ajoint when it is in high use, but the
pain isrelieved by rest. Symptoms progress to constantpain on use
of the affected joint and finally,with more advanced joint
involvement, painoccurs at rest and at night. Generally, little
ten-derness occurs outside the joint, but pain canoccur with
extremes in range of motion. Limi-tation of motion is often
prominent.
Other pathologic processes should not beoverlooked when
evaluating patients withpainful joints. Osteoarthritis can often be
dif-ferentiated from other processes by the historyand physical
examination (Table 1),6 as well aslaboratory studies and
radiographic findings.
Cervical and lumbar pain may result fromarthritis of the
apophyseal joints, osteophyteformation, pressure on surrounding
tissueand muscle spasm. Nerve root impingementcauses radicular
symptoms. Cervical and lum-bar stenosis develop when facet joints
hyper-trophy, the disc degenerates and bulges, andthe ligamentum
flavum becomes lax and
280 AMERICAN FAMILY PHYSICIAN www.aafp.org/afp VOLUME 64, NUMBER
2 / JULY 15, 2001
FIGURE 1. Common sites of involvement in primary
osteoarthritis.
ILLU
STR
ATI
ON
BY
D
AV
ID M
. KLE
MM
The Authors
DANIEL L. SWAGERTY, JR., M.D., M.P.H., is associate professor in
the Departments ofFamily Medicine and Internal Medicine, and
associate director (Education) of the Cen-ter of Aging at the
University of Kansas School of Medicine, Kansas City, Kan.
Hereceived his medical degree and completed a family practice
residency and a fellow-ship in geriatric medicine at the University
of Kansas School of Medicine.
DEBORAH HELLINGER, D.O., is assistant professor and chief of
musculoskeletal radiol-ogy in the Department of Radiology at the
University of Kansas School of Medicine.She received her medical
degree from the University of Health SciencesCollege ofOsteopathic
Medicine, Kansas City, Mo. Dr. Hellinger completed a residency in
diag-nostic radiology at Tulsa Regional Medical CenterOSU.
Address correspondence to Daniel L. Swagerty, Jr., M.D., M.P.H.,
Department of FamilyMedicine, University of Kansas Medical Center,
3901 Rainbow Blvd., Kansas City, KS66160-7370 (e-mail:
[email protected]). Reprints are not available from the
authors.
-
widens. The spinal canal narrows and com-presses the cord.
Posterior vertebral osteo-phytes may also contribute to cord
compres-sion. Patients may develop lumbar pain,extremity weakness,
gait ataxia or abnormalneurologic findings. Pseudoclaudication is
acharacteristic feature of lumbar stenosis and isdescribed as pain
in the buttocks or thighsoccurring with ambulation and relieved
byrest. Hip pain is usually felt in the groin or themedial aspects
of the thigh; however, it can bereferred to the knee or buttocks
and may bemisdiagnosed as lumbar stenosis.
Radiographic FindingsThe diagnosis of osteoarthritis is often
sug-
gested on physical examination. Plain film
radiographs are usually adequate for initialradiographic
evaluation to confirm the diag-nosis or assess the severity of
disease if surgi-cal intervention is being considered. Twoviews of
the involved joint should beobtained, with the possible exception
of thesacroiliac joints and the pelvis. The two viewsshould be
obtained in orthogonal planes to
Osteoarthritis
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FAMILY PHYSICIAN 281
The radiographic hallmarks of primary osteoarthritis
includenonuniform joint space loss, osteophyte formation, cyst
formation and subchondral sclerosis; however, in
earlyosteoarthritis, minimal nonuniform joint space narrowingmay be
the only radiographic finding.
TABLE 1
Clinical Findings Differentiating Osteoarthritis from Other
Causes of Painful Joints
Condition History Physical
Primary Gradual progression of pain Bony enlargement of joints:
DIP, PIP, first osteoarthritis Morning stiffness of one hour or
more carpometacarpal, hips, knees, feet
Pain increasing with weight bearing Usually no wrist, elbow,
ankle or involvement Night pain of MCP No systemic symptoms
Bursitis / Pain increased with movement No joint abnormality or
swellingtendonitis Pain worse at night Certain passive maneuvers
produce pain
No systemic symptoms Pain on resisted active range of motion of
Pain on some maneuvers, not others affected muscles
Mechanical Recurrent joint swelling Pain and limitation at
certain points of flexion intra-articular Joint locks or
extensionconditions Joint gives way Pain on combined rotation and
extension of
Intermittent pain with pain-free intervals the knee
Rheumatoid Often insidious onset Involvement of MCP, wrist,
elbows, anklesarthritis Morning stiffness of one hour or more
Synovial thickening
Systemic symptoms Classic deformities:Associated symptoms (e.g.,
Raynauds Swan neck
syndrome, skin rash) BoutonniereUlnar deviation
Loss of range of motion of wrist, elbows
DIP = distal interphalangeal joint; PIP = posterior
interphalangeal joint; MCP = metacarpal phalangeal joint.
Information from Bagge E, Bjelle A, Eden S, Svanberg A. A
longitudinal study of the occurrence of joint com-plaints in
elderly people. Age Ageing 1992;21:160-7.
-
one another (i.e., anteroposterior [AP] andlateral). Additional
views of weight-bearingjoints (knees, hips) may be necessary.
Corre-lation of radiographic evidence of degenera-tive joint
changes and symptoms described bypatients vary by joint.
Abnormalities detectedin the knees correlate with pain in 85
percent
of patients, the fingers and carpometacarpaljoints in
approximately 80 percent and thehips in 75 percent.6
The radiographic hallmarks of primaryosteoarthritis include
nonuniform joint spaceloss, osteophyte formation, cyst formationand
subchondral sclerosis. The initial radi-ographs may not show all of
the findings. Atfirst, only minimal, nonuniform joint
spacenarrowing may be present. The involved jointspaces have an
asymmetric distribution. Asthe disease progresses, subluxations
mayoccur and osteophytes may form. Subchon-dral cystic changes can
occur. These cysts mayor may not communicate with the joint
space,can occur before cartilage loss and have a scle-rotic border.
Subchondral sclerosis or sub-chondral bone formation occurs as
cartilageloss increases and appears as an area ofincreased density
on the radiograph. In theadvanced stage of the disease, a collapse
of thejoint may occur; however, ankylosis does notusually occur in
patients with primaryosteoarthritis.
KNEE
When evaluating patients with osteoarthri-tis of the knee, AP
and lateral radiographsallow an adequate evaluation of the
medialand lateral joint spaces. To adequately assessthe joint
space, the AP view should be obtainedwith the patient in a standing
position. The lat-eral view also allows evaluation of
thepatellofemoral joint; however, an additionalview, known as the
sunrise view, can offer evenmore information about this joint
space.
Radiographic findings in patients withosteoarthritis include
medial tibiofemoraland patellofemoral joint space narrowing, aswell
as subchondral new bone formation.18,19
Next, lateral subluxation of the tibia occurs,and osteophyte
formation is most prominentmedially. Lateral joint space narrowing
canalso occur but not as prominently as themedial narrowing
(Figures 2a and 2b). Carti-lage is lost, and subchondral bone
formationoccurs. Marked osteophyte formation also
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FIGURE 2. Osteoarthritis of the knees. (A) Anteroposterior view
of theleft knee of patient 1 shows medial joint space narrowing
(arrow). (B) Lateral view of the left knee shows sclerosis with
marked osteo-phyte formation (arrows). The osteophytes are best
seen in this view.(C) Patient 2 has marked osteoarthritic changes
with medial jointspace narrowing (white arrow) causing a varus
deformity of the kneeand collapse of the joint space with
destruction of the medial cartilageand the subchondral cortex (open
arrowheads). (D) Subchondral cysts(solid arrowhead) are noted.
A
B
C
D
-
occurs (Figures 2c and 2d), and osteophytesare seen anteriorly
and medially at the distalfemur and proximal tibia, and posteriorly
atthe patella and the tibia.
HAND
The hand can be evaluated with AP andoblique views; however,
more detail is evidentwith magnified views of the entire hand or
ofa specific joint. Magnification views are par-ticularly helpful
in evaluating the soft tissuesand the fine detail of specific bone.
The mostcommonly involved joints in the hand andwrist are the first
carpometacarpal joints, thetrapezionavicular joint and the
proximalinterphalangeal and distal interphalangealjoints. Joint
space loss is nonuniform andasymmetric (Figure 3). Erosive changes
arenot seen in primary osteoarthritis. In caseswhere an underlying
disease process (such asan inflammatory arthropathy) is present,
sec-ondary osteoarthritis can occur. Post-menopausal women may have
a variant ofosteoarthritis, known as erosive arthritis.20
Only erosive osteoarthritis has erosions andankylosis. The
distribution in the hands andthe feet is similar to that of
osteoarthritis.
HIPS AND PELVIS
AP views of the pelvis can be used to assessarthritic changes in
the hips as well as thesacroiliac joints (Figure 4). Changes
associatedwith the hip include superolateral joint spacenarrowing
with subchondral sclerosis. Thesuperolateral portion of the joint
is theweight-bearing portion. Cystic changes canoccur, and the
femoral head can appear to beirregular.
The true synovial joint space of thesacroiliac joint occurs
anteriorly and inferi-orly. In osteoarthritis, bridging
osteophytesdevelop and extend from the ilium to thesacrum.
Sclerotic changes are also noted, butankylosis or erosions do not
usually developas they do in spondyloarthropathies such
asankylosing spondylitis, psoriasis or Reiterssyndrome.
SPINE
Lateral and AP lumbar spine radiographsare adequate to allow
identification of osteo-arthritic changes in the apophyseal
joints.Decreased joint space is noted between thesuperior and
inferior facets. Sclerosis and cystformation occur in
osteoarthritis of the spine.Neural foraminal narrowing may result
fromthe osteophyte formation. These changes canbe seen on computed
tomographic (CT)
Osteoarthritis
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FAMILY PHYSICIAN 283
Postmenopausal women may have a variant of osteoarthritisknown
as erosive arthritis; the distribution in the hands andfeet is
similar to that of osteoarthritis.
FIGURE 3. Oblique (left) and AP (right) views of the hand
demonstratedecreased joint space and subchondral sclerosis at the
first carpalmetacarpal joint (white arrows). There is old joint
space loss at the PIPand DIP joints with relative sparing of the
MCP joints. Osteophyte for-mation with soft tissue swelling and
subchondral sclerosis is noted atthe 2nd and 3rd DIP joints
compatible with Heberdens nodes (openarrows). (PIP = proximal
interphalangeal; DIP = distal interphalangeal;MCP = metacarpal
phalangeal)
-
scans. Figure 5 illustrates neural foraminalnarrowing caused by
facet osteophyte forma-tion. Similar changes are seen in the
cervicalspine. Primary osteoarthritic changes are notcommonly seen
in the thoracic spine. Osteo-arthritis of the spine is often
associated withdegenerative joint disease.
FOOT
In the foot, AP and lateral radiographs areadequate to assess
osteoarthritic changes, butoblique and magnified views may be
helpfulif a detailed view of a joint space is required.The most
common joint involved is the firstmetatarsophalangeal joint. Again,
subchon-dral sclerosis, osteophyte formation and cys-tic changes
are common. Lateral subluxationof the great toe results in a hallux
valgusdeformity. Osteoarthritic changes elsewherein the foot, such
as the subtalar joint, are usu-ally caused by altered mechanics
from con-genital or acquired abnormalities (e.g., pesplanus, fusion
of two bones) or are secondaryto another underlying arthropathy
(e.g., pso-riasis, Reiters syndrome).
Disease ProgressionFollow-up radiographs are unnecessary in
evaluating progression of the disease but canbe helpful,
especially if surgical intervention isplanned or a fracture is
suspected. Imagingbeyond plain films is not warranted for rou-tine
follow-up; however, in the appropriateclinical situation,
additional types of imagingmay be useful. Nuclear medicine bone
scanscan show radiopharmaceutical localizationbut are nonspecific
in areas of increased boneproduction. Tomography is only helpful if
anoccult fracture is suspected, but routinetomography is not
indicated to monitorosteoarthritis.
While a CT scan is not indicated for an ini-tial evaluation or
as routine follow-up, it maybe helpful in the evaluation of the
lumbarspine to check facet hypertrophy in the man-agement of low
back pain and spinal stenosis.This evaluation can also be
accomplished with
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FIGURE 4. Serial anteroposterior views of the pelvis
demonstrating pro-gressive osteoarthritic changes of the hips.
(Top) The first film,obtained in 1997, demonstrates bilateral,
superolateral joint space nar-rowing (arrows) at the hips that is
worse on the left side. Subchondralsclerosis (solid arrowhead) and
cyst (open arrowhead) formation arealso noted on the left side.
(Center) The March 1999 film shows theinterval increase in joint
space loss (arrow) and sclerosis (solid arrow-head). (Bottom) A
third film, obtained in December 1999, reveals lefthip arthroplasty
(arrow).
-
magnetic resonance imaging (MRI) studies,although the osseous
detail is better appreci-ated with CT scan. MRI also can be helpful
inevaluating cartilage loss but often is unneces-sary because plain
films provide adequateinformation. MRI studies should not be
rou-tinely performed in diagnosing osteoarthritisunless additional
pathology is suspected (e.g.,post-traumatic injuries, malignancy,
neuralforaminal impingement, infectious process).Ultrasonography
can be helpful in diagnosingcystic changes in the soft tissue about
the
joints but is not useful in the initial diagnosisof
osteoarthritis.
Differential considerations are based, inpart, on which joint is
being examined. Ingeneral, the major differential diagnosisincludes
rheumatoid arthritis, psoriaticarthritis, calcium pyrophosphate
depositiondisease, ankylosing spondylitis and diffuseidiopathic
skeletal hyperostosis (Table 2).20
The authors indicate that they do not have any con-
flicts of interest. Sources of funding: none reported.
Osteoarthritis
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FAMILY PHYSICIAN 285
FIGURE 5. (Left) Axial computed tomographic images of the lumbar
spine at the level of L4-5demonstrating hypertrophy of the facets
(solid arrowhead) with sclerosis (black arrow). (Right)Facet
hypertrophy, with or without a disc bulge, can cause stenosis of
the neural foramina (openarrowhead) and nerve root impingement.
Subchondral cyst formation (white arrow) is evident.
TABLE 2
Radiographic Findings Differentiating Osteoarthritis from Other
Causes of Painful Joints
Condition Bone density Erosions Cysts Joint space loss
Distribution Bone production
Osteoarthritis Normal overall No, unless Yes, Nonuniform
Unilateral and/or Yes; osteophytes; erosive subchondral bilateral;
asymmetric subchondral sclerosisosteoarthritis
Rheumatoid Decreased Yes Yes, synovial Uniform Bilateral;
symmetric Noarthritis
Psoriatic Normal Yes No Yes Bilateral; asymmetric
Yesarthritis
CPPD Normal No Yes Uniform Bilateral Yes; osteophytes;
chondrocalcinosis; subchondral
Ankylosing Earlynormal Yes No Yes Bilateral; symmetric
Yesspondylitis Latedecreased
DISH Normal No No No Sporadic Flowing osteophytes; ossification
oftendon, ligaments
CPPD = calcium pyrophosphate deposition disease; DISH = diffuse
idiopathic skeletal hyperostosis.
Information from Brower AC. Arthritis in black and white.
Philadelphia: Saunders, 1998:23-57.
-
Osteoarthritis
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