Full text of DOI:10.1007/s00402-002-0414-7

Arch Orthop Trauma Surg (2002) 122:469–471
DOI 10.1007/s00402-002-0414-7
CASE REPORT
Hirokazu Kobayashi · Shaw Akizuki ·
Tsutomu Takizawa · Yukihiro Yasukawa · Jyun Kitahara
Three cases of pseudogout complicated
with unicondylar knee arthroplasty
Received: 7 August 2001 / Published online: 21 June 2002
© Springer-Verlag 2002
(Fig.1and 2). No calcium deposits were seen macroscopically in
Abstract Pseudogout is an uncommon complication of
arthroplasty, so it is important to distinguish pseudogout
from infection. We experienced three patients with the
acute onset of pseudogout after unicondylar knee arthro-
plasty (UKA). Treatment with nonsteroidal anti-inflam-
matory drugs (NSAID) and cooling improved the symp-
toms of all three patients, and there have been no further
episodes. Because there is a large area uncovered by the
UKA prosthesis, it is necessary to keep in mind the possi-
bility of pseudogout affecting the operated knee.
the joint on inspection during the operation. The synovial fluid was
cloudy and pale yellow in color, and calcium pyrophosphate dihy-
drate (CPPD) crystals were detected that were refraction negative
on polarized microscopy. Culture for bacteria was negative. Histo-
logical examination showed CPPD crystals within the synovial
membrane resected during the operation in this patient (Fig.3).
There was a sudden increase of the C-reactive protein (CRP) level
in this patient during the pseudogout attack, but the white blood
cell count (WBC) remained within the normal range. CRP returned
to normal within 1 week (Fig.4). He was diagnosed as having
pseudogout and showed marked improvement of symptoms after
treatment with a nonsteroidal anti-inflammatory drug (NSAID)
and cooling. This patient has continued on a low dose of NSAID
over the long term and has not experienced any repeat attacks.
Keywords Complication · Pseudogout · Unicondylar
knee arthroplasty
Introduction
We report three cases of pseudogout with symptoms re-
sembling infection after unicondylar knee arthroplasty
(UKA). When complications occur after UKA, this prob-
lem should be kept in mind, since it is important for
pseudogout to be distinguished from infection.
Case reports
Case 1
The patient was a 74-year-old man with osteoarthrosis (OA) who
underwent UKA of the left knee joint on April 5, 1994. Four weeks
after surgery, severe pain, swelling, redness, and heat were sud-
denly noted in the left knee. Antibiotics were administered for sus-
pected postoperative infection but did not produce any improve-
ment of his symptoms. No calcium deposits were evident in the
joints of this patient on X-ray films taken before and after surgery
H. Kobayashi · S. Akizuki (✉) · T. Takizawa · Y. Yasukawa ·
J. Kitahara
Department of Orthopaedic Surgery and Rehabilitation,
Nagano Matsushiro General Hospital,
Matsushiro183 Nagano, Japan
e-mail: sakizuki@hosp.nagano-matsushiro.or.jp,
Fax: +81-26-2789167
Fig. 1 X-ray findings before surgery (case 1). No calcium de-
posits were evident in the joint of this patient on X-ray films taken
before surgery

470
Fig. 2 X-ray findings after surgery (case 1). No calcium deposits
were evident in the joint of this patient on X-ray films taken after
surgery
Fig. 4 An electrolyte change. There was a sharp rise of the C-reac-
tive protein level in all of the patients during the pseudogout attack,
but the white blood cell count remained within the normal range
agnosed as having pseudogout and showed marked improvement
of symptoms after treatment with NSAID and cooling.
Case 3
The patient was an 82-year-old man with OA who underwent bi-
lateral UKA on April 7, 1998. Two weeks after surgery, he sud-
denly developed severe pain, swelling, and heat in both knees
without any predisposing factors. He was given antibiotics for sus-
pected infection, but showed no response. No calcium deposits were
evident in the joints on X-ray films obtained before and after sur-
gery. No calcium deposits were seen macroscopically in the joints
on inspection during the operation. The synovial fluid was cloudy
and pale yellow. It contained CPPD crystals that were refraction
negative on polarized microscopy, while culture for bacteria was
negative. Histological examination showed no CPPD crystals in the
synovial membrane resected at the time of operation. There was
again a sudden increase of CRP in this patient during the pseudogout
attack, but the WBC remained normal. CRP decreased markedly
after 3 days and returned to the normal range within 1 week (Fig.4).
He showed marked improvement of his symptoms after NSAID
therapy and cooling.
Fig. 3 Histological findings (hematoxylin and eosin, ×50). Histolog-
ical examination showed calcium pyrophosphate dihydrate (CPPD)
crystals in the synovial membrane in case 1
Case 2
The patient was a 79-year-old man with OA who underwent UKA
of the right knee joint on May 24, 1995. No symptoms occurred
postoperatively for several years, but suddenly severe pain, swelling,
and redness of the right knee developed in January 1998. The sy-
novial fluid was reddish-brown and bloody. It contained CPPD
crystals that were refraction negative on polarized microscopy.
Culture for bacteria was negative. Histological examination showed
no CPPD crystals in the synovial membrane resected during the
operation in this case. There was also a sudden increase in the CRP
level in this patient during the pseudogout attack, but the WBC re-
mained within the normal range. CRP decreased markedly after
Discussion
Postoperative infection is the most serious complication
of arthroplasty and requires careful attention.
Pseudogout differs from septic arthritis and postopera-
tive infection in that the patient’s general condition is good
relative to the local findings, and tapping of the joint fluid
3 days and returned to normal within 1 week (Fig.4). He was di- results in rapid improvement of symptoms. A definitive di-

471
agnosis of pseudogout can be made if CPPD crystals are nor were CPPD crystals seen postoperatively in pathology
detected in the joint fluid by polarized microscopy and if specimens from cases 2 and 3. The three patients described
synovial fluid cultures are negative [4]. It is important to here accounted for 3% of our series of UKA cases and
keep the possibility of postoperative pseudogout in mind, show that pseudogout can occur even when preoperative
since symptoms improve dramatically in response to cool- radiographs give no indication of the disease. Pseudogout
ing and NSAID administration [1].
is a very rare complication of arthroplasty according to the
Pseudogout is classified into the following clinical literature. Compared with TKA, there are some features
types: A (pure pseudogout attacks), B (pseudorheumatoid predisposing to attacks of pseudogout after UKA: (1) the
arthritis), C (OA with pseudogout attacks), D (OA without large area of unreplaced joint surface, (2) preservation of
pseudogout attacks), E (asymptomatic), F (pseudoneuro- the meniscus and cruciate ligaments, and (3) the relatively
pathic OA), G (monoarthritis), G+ (type G with attacks af- good knee function as a result of a greater range of mo-
ter trauma or surgery), H (hemarthrosis), I (isolated masses), tion. The disease is easily mistaken for postoperative in-
Das (pseudoankylosing spondylitis), and Dp (spinal com- fection because the symptoms (local pain, swelling, and
pression) [2, 6]. Cases 1 and 3 appeared to be type G+, heat) and the characteristics of the synovial fluid resemble
while case 2 was type H.
those found in infection [3, 5]. Therefore, it is important
Pseudogout attacks can occur during the treatment of to keep in mind the possibility of postoperative pseudo-
trauma as well as before or after surgery. We had 1 patient gout when diagnosing and treating arthroplasty patients.
who experienced pseudogout in the knee after surgery
among 150 patients who underwent total hip arthroplasty,
as well as 2 patients with pseudogout of the knee on the References
operated side before surgery and one with involvement of
the contralateral knee after surgery among 300 patients
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experienced pseudogout in the operated joint. In the series
of 98 patients (134 knees) who underwent UKA at our
hospital, we encountered 3 who developed pseudogout in
the operated knee after surgery. Intraarticular calcium de-
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tients before surgery in our hospital. However, no such
deposits were observed on preoperative radiographs in
any of the three patients described in the present report,
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