Sea Urchin Puncture Resulting in PIP Joint Synovial Arthritis:
Case Report and MRI Study
N. Liram, M. Gomori, and M. Perouansky
Of the 600 species of sea urchins, approximately 80
may be venomous to humans. The long spined or black
sea urchin, Diadema setosum may cause damage by the
breaking off of its brittle spines after they penetrate the
skin.
Synovitis followed by arthritis may be an unusual but
apparently not a rare sequel to such injury, when implantation occurs near a joint. In this case report, osseous
changes were not seen by plain x-rays. Magnetic resonance imaging (MRI) was used to expose the more
salient features of both soft tissue and bone changes of
black sea urchin puncture injury 30 months after penetration. In all likelihood, this type of injury may be more
common than the existing literature at present suggests.
It is believed to be the first reported case in this part of
the world as well as the first MRI study describing this
type of joint pathology.
Local and systemic reactions to puncture injuries
from sea urchin spines have been described previously.1
These may range from mild, local irritation lasting a
few days to granuloma formation, infection and on occasions systemic illness.1,2
The sea urchin spines are composed of calcium carbonate with proteinaceous covering. The covering tends
to cause immune reactions of variable presentation.3,4
There are only a handful of reported cases with sea
urchin stings on record, none of them from the Red Sea.
However, this condition is probably more common than
is thought and can present difficulty in diagnosis.3 In this
case report, the inflammation responded well to heat treatment, mobilization and manipulation of the joint in its
post acute and chronic stages. As some subtle changes in
soft tissues and the changes in bone were not seen either
on plain x-rays or ultrasound scan, gadolinium-enhanced
MRI was used to unveil the marked changes in the
joint.
Case Report
An otherwise healthy 42-year-old male Caucasian
scuba diver presented with pain and some swelling in the
proximal interphalangeal joint (PIP) of the left 3rd digit.
There was a 24 hour history of sea urchin puncture
with multiple penetrations of spines into his left hand.
The patient experienced pain, discomfort and stiffness
of the hand initially. The spines in the carpal region
were absorbed within a few days, leaving the 3rd digit
swollen and painful. Flexion of the joint was markedly
reduced and hand gripping power significantly compromised. Plain x-rays revealed soft tissue swelling with
no other changes. Treatment consisted of ultrasound
therapy, hot packs and mobilization. There was improvement over a 3 week period, restoring about 50% of the
normal flexion as compared to the right 3rd digit. The
swelling reduced and hand strength was recovered within
6 weeks.
After 6 months of home application of heat packs
and rehabilitation exercises with physiotherapy squeezeputty, there was residual joint swelling and range of flexion restriction, as well as pain upon lateral pressure of the
joint. X-rays revealed no change as compared to the film
taken after the injury. The patient was referred to a
rheumtologist and was offered local injection of methylprednisolone acetate (Depo Medrol), which he declined.
After 30 months,the swelling and sensitivity persisted,
leaving mild mechanical flexion dysfunction of the digit.
Another anterior-posterior view was taken with no visible change other than soft tissue swelling. Ultrasound scan
of the joint was performed in an attempt to view the soft
tissue changes.
The scan did not show any difference between the
affected joint and other adjacent joints. At that point, the
consulting radiologist suggested an MRI scan with contrast in order to correlate the clinical findings with imaging evidence.
N. Liram, DC: Hadassah University Hospital (HUH),
Department of Orthopaedics, Spine Surgery Unit. Ein-Karem,
Jerusalem, Israel and the Anglo-European Chiropractic
College, Bournemouth U.K; M. Gomori, MD: Hadassah
University Hospital, Department of Radiology, MRI Unit; M.
Perouansky, MD: Hadassah University Hospital, Department
of Anaesthesiology.
Imaging
Reprint requests: N. Liram, DC: Spine Surgery Unit, Dept. of
Orthopaedics, Hadassah University Hospital, Ein Karem
Jerusalem P.O.B. 12000 Jerusalem 91120 Israel.
MRI showed intra articular soft tissue swelling particularly on the medial aspect of the joint. There was moderate hyperintensity on T-1 and T-2 weighted imaging.
J Travel Med 2000; 7:43–45.
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J o u r n a l o f Tr a v e l M e d i c i n e , Vo l u m e 7, N u m b e r 1
Figure 2 “MRI of the left 3rd PIP joint with gadolinium enhancement.” Outlining the surrounding synovitis, degenerative and
soft tissue changes.
Figure 1 “A-P radiogram of the left 3rd PIP joint.” Periarticular swelling seen.
Significant but not intense enhancement after contrast
administration was evident, with good demarcation from
the adjacent soft tissue which did not demonstrate significant surrounding edema.
These findings are consistent with chronic, active synovial inflammation with surrounding fibrosis. There is suggestion of a traction spur laterally and medially and some
cortical remodeling possibly indicating the involvement
of tendon insertions and adjacent cortex. These are visible on both T-1 and T-2 weighted images and may suggest enthesopathy.5
All these findings are consistent with a chronic,
“smouldering” process. These changes were not seen on
radiographic or ultrasound examination.6
However, in the minority of cases this type of marine
animal sting can be a potential cause of severe, irreversible tissue damage. As subaquatic activity is becoming increasingly popular in the 90s and sea urchin
puncture is an everyday event (more common in night
diving), some attention must be paid to avoidance by forethought. Changes in ecosystems render some sea urchin
species more prolific, at the unfortunate expense of other
marine reef inhabitants.8,9
Dreyfus et al. reported two cases in the early 80s
involving articular damage resulting from sea urchin
spine wound.10–12 One case involved an interphalangeal
joint of a male adolescent diver. The second case report
involved a middle aged female diver who developed
extensive arthritis with deformity and palmar fibrositis.
Synovial histology revealed a combination of pasteurellosis infection together with giant cell granulomatous
synovitis.
Discussion
Sea urchin puncture injuries are regarded as unpleasant by recreational and professional divers. Dive instruction and its respective professional literature indicates that
such accidents result in no more than a painful encounter.7
Figure 3 “MRI of the left 3rd PIP joint.” Fibrosis and traction
spurs seen.
L i r a m e t a l . , S e a U r ch i n P u n c t u r e R e s u l t i n g i n P I P J o i n t S y n o v i a l A r t h r i t i s
McHugh and Tweed reported in 1984 a case of a
35-year-old Chatham Island fisherman presenting with
persisting right ankle inflammation following sea urchin
spine penetration. Limitation of movement and swelling
was present, as well as plain x-ray findings of opacities
in the soft tissues anterior to the joint. Upon surgical
exploration, extensive synovitis of the extensor tendons
was noted. There was a finding of microscopic foreign
fragment particulate material from the urchin spine in
the tendon sheath synovial biopsy.3
In the case reported here,arthritic changes to the joint
are observed, with corresponding mechanical defects. It
is unlikely that surgical intervention was indicated in the
initial stages of reactive synovitis. The joint seems to be
stable and it is unlikely that surgery may be required in
the future. It may be assumed that many cases similar to
this one occur without reaching the literature. The moderate clinical consequences and lack of standard bone radiography changes leave this type of injury neglected.
The MRI study in this case report highlights the
changes in the joint following sea urchin spine puncture.
It may be speculated that the synovial irritation
mediated by the immunological and chemical reactions
from the foreign body and its protein covering also led
to direct tissue damage. On reflection of how this case
was managed, some or even most of the long standing
tissue damage might possibly have been avoided with the
early administration of methylprednisolone acetate aqueous suspension by local injection.13 Obviously, precise
determination of such a treatment course must entail several cases and a control group.
Conclusions
There is a tendency to overlook sea urchin spine
injury since it resolves without major discomfort or
consequences. Due to the nature of this marine animal
and human subaquatic limitations, hand and foot injuries
are commonest, the reason being that the poisonous sea
urchin spines penetrate into synovial joints in the carpal
and tarsal regions which are relatively unprotected by a
thicker muscle mass or artificial protection.
This case report with MRI investigation outlines the
dangers of such an accident. It is important that diving
associations and physicians dealing with marine animal
45
stings and bites are informed of the potential long-term
damages resulting from this type of injury.
When imaging joints and their adjacent soft tissues,
MRI is a better diagnostic tool than plain x-rays and ultrasound. X-rays are very limited in showing soft tissues.
Hence, a diagnosis based on subtle changes in synovium
and small muscle-insertions cannot be based on plain radiographs. Ultrasound is better than x-rays at imaging soft
tissues. However, the ultrasound beam does not penetrate
the bone and visualization is adequate only directly
underneath the transducer. MRI does not have these
limitations.
References
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