Keywords
Anaerobes - computed tomography - emphysematous osteomyelitis -
Enterobacteriaceae
- intraosseous gas
Introduction
Presence of intraosseous gas in appendicular skeleton in the absence of a history
of surgery, trauma, or degenerative changes is highly suggestive of emphysematous
osteomyelitis. However, the presence of intraosseous in vertebral bodies is generally
due to a noninfectious cause, most commonly being degenerative process.[1],[2] We present two cases of this rare entity aged 56 years and 25 years diagnosed with
emphysematous osteomyelitis of bilateral, mid, distal foot and left hip joint, respectively.
Case Reports
Case 1
A 56-year-old male admitted to our hospital with complaints of burning micturition
and severe pain and swelling in both the feet. He had a medical history relevant for
Type 2 diabetes mellitus and chronic alcohol consumption. He had an irregular intake
of the oral hypoglycemic drugs prescribed from a local physician. No history of trauma
or surgery was given.
On examination, he was febrile with body temperature of 38.4°C. Lower extremity examination
revealed swelling and tenderness over both dorsal and plantar aspects, more on the
plantar aspect. Posterior tibial pulse was normal; however, dorsalis pedis pulse could
not be elicited due to severe tenderness and swelling. Laboratory findings revealed
leukocytosis (30 × 109 L−1 with 80% neutrophils), elevated C-reactive protein (>2.8 mg/L), HbA1c was ~8.3%.
Liver and renal function tests were within the normal limits. His urine examination
revealed pus cells (15–20), 1 + sugar, trace albumin, and no casts/crystals. Red blood
cells were 0–1per high power field.
Specimens for urine culture were obtained prior to start of empirical antibiotic –
ciprofloxacin. His blood glucose levels were managed with intravenous insulin. Sensitivity
testing later revealed growth of Escherichia coli after 24-h incubation sensitive to ciprofloxacin, gentamicin, and piperacillin. Gram
stain revealed growth of gram-negative bacilli.
He was then referred to the Radio-diagnosis Department for X-ray of both of his feet,
which did not reveal any significant abnormality, but his excruciating pain prompted
us for further evaluation. Color Doppler study of lower limb was performed, which
revealed mild intimal wall thickening of the arteries and normal color flow and spectral
pattern in femoral artery, popliteal artery, and anterior and posterior tibial arteries.
Dorsalis pedis artery could not be assessed because of excessive swelling over the
feet. Further during his course of hospital stay, computed tomography (CT) angiography
of lower limb vessels was planned, which did not reveal any vascular pathology. However,
multiple gas pockets were seen in tarsals, metatarsals, as well as phalanges of both
feet. Air locules were also noted in the surrounding soft tissues. Possibility of
emphysematous osteomyelitis with necrotizing fasciitis was considered and the patient
was urgently planned for bilateral below ankle amputation [Figure 1]A,[Figure 1]B,[Figure 1]C,[Figure 1]D. Patient was started on piperacillin and tazobactam postoperatively. Tissue specimens
obtained from the amputated part were sent for gram stain and culture, which again
revealed growth of E. coli, thus pointing toward possible source of infection being urinary tract. No further
complications occurred on follow-up.
Figure 1 (A-D): (A) Plain radiography of foot (lateral view) of 56 year old male depicting soft tissue
thickening along dorsal and plantar aspect. (B) CT lateral view of foot showing presence
of gas in metatarsal, tarsal bones (white arrow), phalanges and in soft tissues (blue
arrow). (C) CT axial view of both feet depicting presence of intraosseous gas in metetarsal,
tarsal bones (white arrow) and in soft tissues. (D) CT axial view of metatarsal bones
depicting intraosseous gas (white arrow) and gas in soft tissues (red arrow)
Case 2
A 25-year-old female was admitted to the emergency department complaining of left
hip pain and difficulty walking since 3 days. She was diagnosed with acquired immunodeficiency
syndrome about 2 months ago and was taking prescribed highly active antiretroviral
therapy. She gave no history of trauma or surgery. On examination, she was afebrile
with normal vitals. Her neurological examination was normal and her lower limb examination
revealed mild tenderness over the left gluteal region; however, deep tendon reflexes
and power were within the normal limits. Laboratory examination showed normal blood
cell counts. Her CD4+ T-cell count was 300 (within normal limits). She was referred
to Department of Radio-diagnosis for plain radiograph of pelvis, which did not reveal
any significant abnormality. She was subsequently discharged with a prescription of
antiinflammatory drugs.
She returned a week later with the same complaints. On examination, she was tachycardic
and febrile with a body temperature of 38.2°C. Her lower examination revealed pain
on flexion and extension of left hip joint. The lower limb pulses were within the
normal limits.
She was then referred to Radio-diagnosis Department. Since her plain radiographs were
within the normal limits in the initial visit, she was investigated with a CT scan
of the lower abdomen. Multiple air locules were noted in the left iliac blade and
acetabulum with multiple ill-defined hypodense areas in periarticular muscles of left
hip joint with surrounding fat stranding [Figure 2]A,[Figure 2]B,[Figure 2]C. A possibility of emphysematous osteomyelitis was considered and she was subjected
for a fine needle aspiration cytology, a specimen of which was also sent for culture
and sensitivity tests. She was empirically started on metronidazole and piperacillin.
Her gram stain revealed gram-negative rod-shaped bacteria. Culture and sensitivity
revealed growth of Klebsiella pneumoniae sensitive to piperacillin, amikacin, and ciprofloxacin. She was put on piperacillin
and tazobactam, and metronidazole was discontinued. No complications were noted on
follow-up.
Figure 2 (A-C): (A) Plain radiograph of pelvis AP view depicting no significant abnormality. (B)
CT axial of hip joint showing presence of intraosseous gas in left acetabulum (white
arrow) and ill-defined hypodense areas in periarticular muscles of left hip joint
(blue arrow) (C) CT axial view of pelvis depicting few air locules in left iliac blade
(white arrow)
Discussion
Emphysematous osteomyelitis is a rare and potentially fatal condition characterized
by the presence of intraosseous gas.[3] Only 25 cases have been reported in the literature so far with common locations
being pelvis, femur, tibia, fibula, thoracolumbar vertebra.[1] Mautone et al.[4] reported the first case of emphysematous osteomyelitis of midfoot, in 2014, which
is an unusual location for its occurrence. To the best of authors’ knowledge, we reported
the second case of emphysematous osteomyelitis of midfoot with associated involvement
of the distal foot. Also, we believe this is the first reported case of involvement
of bilateral feet. There is no gender predilection for its occurrence.
Hematogenous dissemination is the most common route of spread of infection.[5],[6] However, McDonnell et al. have also reported rare modes of disease spread, such as an extension of intraabdominal
infection, intraabdominal, or spinal surgery, or from skin or soft tissue infection.[2]
Presence of intraosseous gas in intravertebral space is generally a feature of disc
degeneration; however, extensive intraosseous gas, bone marrow edema, and/or adjacent
fluid collections should raise the possibility of emphysematous osteomyelitis, which
was the possible scenario in our second case that showed evidence of intraosseous
gas with adjacent fluid collection in the pelvis.[5]
Monomicrobial or polymicrobial infection by anaerobes or members of Enterobacteriaceae
family is generally the cause of infection,[1],[3],[7] which was the same in all of our cases.
Certain differential diagnoses, such as penetrating wounds, open fractures, postbiopsy,
lymphangiomatosis of bone, need to be excluded before diagnosing a case with emphysematous
osteomyelitis.[7],[8]
A radiologist plays a critical role in diagnosing a case of emphysematous osteomyelitis
as prompt management is required once a case is confirmed. Plain films can be helpful
in detecting the air pockets in bone and soft tissues, but did not provide any clue
to point to this diagnosis in both of our cases. CT detection of intraosseous gas
was first described by Ram et al. in 1981.[7] Our CT findings diagnosed our cases with sufficient confirmation and also described
the entire extent of the spread. Ultrasonography has a very limited role as it is
difficult to diagnose air in soft tissues. Magnetic resonance imaging can also detect
the presence of gas, but there is paucity of literature on its correlation with CT
in detection of intraosseous gas.
The patients in our study were referred to surgical department for their management,
with one of them being managed with combined surgical and medical treatment and the
other responded to antibiotic therapy.
Conclusion
Emphysematous osteomyelitis is a rare condition, which if not diagnosed early has
significant morbidity and can even prove fatal. CT plays a vital role in the diagnosis
and extent of this condition, thus emphasizing indispensable role of a radiologist.
