2.CASE PRESENTATION
A previously healthy 28-year-old Tunisian man was admitted to our
Department of internal medicine on april 2022 with a painful swelling of
her right knee with more than twelve month history of persistent pain,
stiffness and functional disability. Her history revealed that symptoms
occured two weeks after the second shot of coronavirus mRNA BNT162b2
(Comirnaty Pfizer–BioNTech) COVID-19 vaccine (the first dose was also
Comirnaty)
He was treated with nonsteroidal anti-inflammatory drugs (NSAIDs)
without any relief. His pain and disability were worsened to the point
that his daily activities were restricted (walk, managing
stairs…), and his work was badly compromised.
He reported that pain and weakness were evident the night with an
average intensity of 9 on a numeric rating scale (NRS) of 0 to 10.
On examination, the right knee showed mild not pitting edema with
tactile allodynia, extreme restriction of knee joint on active and
passive movement and major atrophy of the right muscles. There was
tactile allodynic response to any palpation on anterior and medial area
of the knee The left knee and the upper limbs were both normal.
Blood screening which include a sedimentation rate (4 mm first hour),
C-reactive protein (18 mg/l), full blood counts (white blood cell count
, hemoglobin level and platelet level) , electrolytes, creatinine,
fasting glucose, liver function tests (including Total bilirubin , ASAT
and ALAT GGT), creatine phosphokinase were all normal. Serum rheumatoid
factor, anti-citrullinated peptides, antinuclear antibodies (ANA),
Anti-neutrophil cytoplasmic antibodies (ANCA) and hepatitis B and C
viral screening were all negative. The Thyroid stimulating hormone (TSH)
value was normal at 0,69 mUI/L. 25-hydroxy vitamin D level was found to
be low (17 ng/mL). There was no evidence of obvious infectious and all
bacteriological studies were negative. An electromyography of the lower
limbs was performed and did not show any pathologic findings.
MRI of the right knee was performed and showed extensive patchy bone
marrow edema with high signal within the femur , the tibia and the
patella in proton density weighted fat saturated sequences , with a mild
joint effusion without fractures lines (Figures 1 and 2).
Therefore, the diagnosis of CRPS of the right knee after COVID-19
vaccination was made.
Many treatments were tried with unsatisfactory pain relief :
intra-articular knee injections, pregabalin, opioids. The patient was
was managed with extensive and regular physiotherapy including muscle
strengthening and functional training. He was started alendronate 70 mg
orally twice a week , calcium carbonate - cholecalciferol
supplementation with psychotherapy to reduce anxiety
The patient responded very slowly to the treatment and began to show
marked improvement in pain, range of movement and function but without
complete recovery.
A second MRI was performed 8 months after the diagnosis (Figure
3). It showed a mild dicrease of the signal of the bone marrow edema
within the femur and tibia, marked improvement of the edema within the
patella; Persistance of the joint effusion. A bone
resorption and muscle hypotrophy were observed.