Australian Doctor Australian Doctor 15th December 2017 | Page 20

How to Treat – Psoriatic arthritis
Investigations
Serology
HLA B27 is positive in 25% of
patients with psoriatic arthritis,
while RF and CCP are negative in
95% of patients. It is important to
note that the ESR and CRP, even in
patients with active disease, are not
elevated in 60% of patients. 18
Imaging
Radiographs can assist diagno-
sis if there are classic changes of
joint resorption, eccentric ero-
sions and new bone formation
(see figure 6). 19 However, normal
radiographs do not exclude the
diagnosis.
Ultrasound is useful particularly
in characterising tenosynovitis
and synovitis, and Power Doppler
ultrasound is valuable in identify-
ing active disease.
In patients with presentations
involving entheseal attachments,
Power Doppler can provide blood
flow information and assist in dif-
ferentiating inflammatory from
non-inflammatory causes. 20
MRI has a role in diagnosing
psoriatic arthritis and sacroiliitis
(see figures 7, 8 and 9) in patients
with suspected psoriatic arthritis. 21
The most important lesion in
the sacroiliac joints is osteitis
(formerly bone marrow oedema),
a lesion best appreciated on T2
weighted images using a fat sup-
pressions sequence (usually STIR).
Ligament and tendon attach-
ment sites are frequently involved
and can be identified on the T2
weight sequence.
Synovitis within the sacroiliac
joint is visible on post Gadolinium
Figure 7. Psoriatic arthritis of the spine.
Signs of active inflammation are seen
at several levels (arrows). In particular,
anterior spondylitis is seen at level L1/
L2 and an inflammatory Andersson
lesion at the upper vertebral endplate
of L3.
from page 18
Source: Arthritis Research & Therapy
2006; 8:207. See:bit.ly/2g5EHz9
Figure 6. Anteroposterior X-rays of
left hand in a patient with psoriatic
arthritis.
T1 weight images but is not essen-
tial for diagnosis and gadolinium
is not required routinely.
Sclerosis, erosions and fat
metaplasia are chronic lesions
best appreciated on T1 weighted
images. These lesions represent
damage (erosions) and chronicity
(sclerosis and fat metaplasia).
In the peripheral joints, MRI is
useful in differentiating inflamma-
tory lesions (entheseal pain) from
non-inflammatory lesions, imag-
ing tenosynovitis and detecting
hallmarks of inflammatory dis-
ease, including osteitis and syno-
vitis. 22
Differential diagnosis
Differentiating psoriatic arthritis
from other forms of joint disease
is important in stratifying therapy.
Key differentiating features are
summarised in table 4.
Figure 8. Sacroiliitis on MRI.
Source: Arthritis Research & Therapy 2006, 8:207.http://bit.ly/2zaCIye
Management
MANAGING psoriatic arthritis
includes not only the joint symp-
toms, but skin and nail disease
and any comorbidities. Treat-
ments are tailored to the patient
based upon the severity of joint
and skin symptoms as well as the
severity of comorbidities.
Education and exercise
Figure 9. Psoriatic arthritis of the fingers.
MRI (a) precontrast and (b) postcontrast coronal images of the fingers in a patient with psoriatic arthritis. Enhancement
of the synovial membrane at the third and fourth proximal interphalangeal and distal interphalangeal joints is seen,
indicating active synovitis (large arrows). There is joint space narrowing with bone proliferation at the third PIP joint and
erosions are present at the fourth distal interphalangeal joint (white circle). Extracapsular enhancement (small arrows)
is seen medial to the third and fourth PIP joints, indicating probable enthesitis. Note that this particular slice does not
allow optimal visualisation of all of the mentioned pathologies.
Source: Arthritis Research & Therapy 2006, 8:20 http://bit.ly/2xsTLyi
Table 4. Summary of differentiating features among forms of arthritis
Psoriatic arthritis Rheumatoid arthritis Osteoarthritis Gout
Onset joint
distribution Asymmetric Symmetric Asymmetric Asymmetric
Most common
patterns Oligoarticular, mono or
polyarticular Polyarticular Mono – or
oligoarticular Mono – or oligoarticular
Sacroiliitis Common Uncommon Absent Absent
Erythema
accompanying
joint swelling Common Rare Absent Common
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Patient education and support is
vital in the management of pso-
riatic arthritis. Having a diagno-
sis is an important first step for
patients. Education should include
an explanation of the nature of the
condition and the importance of
medical therapy, combined with
management of comorbidities (for
example, weight loss).
Prednisolone
Prednisone can be used to control
acute symptoms utilising low-
dose therapy (10-20mg daily)
and tapering slowly, usually with
the introduction of conventional,
synthetic disease-modifying anti-
rheumatic drugs (csDMARDs) to
reduce the risk of psoriasis flare
ups as steroids are tapered. 23
Conventional synthetic
DMARDs
Methotrexate, salazopyrine and
leflunomide are standard, conven-
tional synthetic DMARD therapies
for psoriatic arthritis. Although
widely utilised in clinical practice,
evidence for the efficacy of each of
these agents is minimal.