Slipping Rib Syndrome - Journal of Ultrasound in Medicine

Slipping Rib Syndrome
A Place for Sonography in the Diagnosis
of a Frequently Overlooked Cause of
Abdominal or Low Thoracic Pain
Abbreviations
SRS, slipping rib syndrome
Received August 8, 2001, from the Department of
Diagnostic and Interventional Radiology, University
Hospital, Lausanne, Switzerland. Revision requested
September 20, 2001. Revised manuscript accepted
for publication October 22, 2001.
Address correspondence and reprint requests to
Jean-Yves Meuwly, MD, Department of Diagnostic
and Interventional Radiology, University Hospital,
rue du Bugnon 46, 1011 Lausanne, Switzerland.
Jean-Yves Meuwly, MD, Stephan Wicky, MD,
Pierre Schnyder, MD, Domenico Lepori, MD
Case Series
Objective. To describe the sonographic appearance of a poorly recognized cause of low thoracic or
upper abdominal pain. Methods. Three sonographic descriptions of slipping rib syndrome are presented.
Results. The 3 patients had abnormal mobility of a cartilaginous rib, which could slip over an
adjacent rib during abdominal muscle contraction. Conclusions. Slipping rib syndrome should be considered
in patients with histories of upper abdominal or low thoracic pain of unknown origin. We suggest
that high-resolution sonography of the costal margin should be added to abdominal sonography
in cases of nonspecific abdominal pain. Key words: abdominal pain; chest pain; joint diseases; ribs;
sonography.
lipping rib syndrome (SRS) is a mechanical
cause of pain of the upper abdomen or lower
chest. First reported in 1919 by Cyriax, 1 this disorder
may account for 1% to 5% of all causes of
consultation in a general medical practice. 2 Despite
this high prevalence, this syndrome remains frequently
missed, and patients are often exposed to extensive
and unnecessary investigations for unclear symptoms. 3
Slipping rib syndrome has been reported as a pure clinical
diagnosis, and to our knowledge, no diagnostic test
had been available to corroborate the clinical finding
until now. This lack has been considered one of the reasons
for overlooking the syndrome4 S
Here we describe 3
cases in which, in an unclear clinical context, the diagnosis
of SRS was established by sonography.
© 2002 by the American Institute of Ultrasound in Medicine • J Ultrasound Med 21:339–343, 2002 • 0278-4297/02/$3.50

Slipping Rib Syndrome
Case Reports
Case 1
A 20-year-old cricketer was admitted to the
emergency department with acute pain in the
upper right abdomen. This pain occurred
abruptly after abdominal wall overstretching
during a cricket match. At clinical examination,
the right upper abdomen and the inferior anterior
border of the thoracic wall were painful.
Neither a mass nor skin discoloration could be
observed. Biological test results were normal,
and the patient had no fever. An abdominal wall
sonographic examination was performed to rule
out a tear of the abdominal muscles. Sonography
with a high-frequency linear probe (L12-5 with
SonoCT and HDI 5000 systems; Philips Ultrasound,
Bothell, WA) showed slipping of the
eighth costal cartilage on the lower edge of the
seventh rib, repeatedly triggered by Valsalva
maneuvers (Fig. 1). During contraction of the
rectus muscle, the eighth rib was initially displaced
against the anterior aspect of the lower
border of the seventh rib. As the contraction
increased, the eighth rib was suddenly pushed
in. Simultaneously, a rebound effect was perceptible
under the probe at the very moment the
patient felt pain. Because the symptoms did not
improve with conservative treatment, surgical
removal of the extremity of the eighth rib was
performed. The rib was totally normal at pathologic
examination. The symptoms disappeared
after the procedure.
Case 2
A 36-year-old nurse had chronic dull pain in the
left upper abdomen for 4 months. The pain
increased during work and subsided at night.
The patient reported that moving patients was
particularly painful. She had no history of trauma
or excessive muscular activity. Physical examination
proved inconclusive. Neither biological
abnormalities nor fever was observed. The
patient had a sonographic examination of the
abdomen, performed with the high-frequency
linear probe and systems described above. As the
patient performed a Valsalva maneuver during
real-time sonography, slipping of the left ninth
rib around the eighth rib was obvious, precisely
in the area of tenderness. The displacement of
the ninth rib was closely and repeatedly related
to the Valsalva maneuver and contraction of the
rectus muscle. A clicking of the rib as it slipped
was perceptible with the probe. The patient perfectly
understood the explanation about the origin
of her pain and the symptoms improved
within 2 weeks after the sonographic examination
without any further treatment.
Case 3
A 53-year-old man had right upper abdominal
pain, worsened by coughing, for 3 months.
Physical examination findings were normal, and
there was no biological abnormality. Previous
investigations included gastroscopy, computed
tomography of the abdomen, and chest radiography.
Sonography was ordered to rule out a gallbladder
or biliary tree abnormality. During
sonographic examination of the abdomen,
which revealed neither cholelithiasis nor biliary
disease, the abdominal wall was also explored
with the high-frequency transducer described
above. Slipping of the eighth rib around the seventh
rib was visible during the Valsalva maneuver
at the moment when the patient felt pain. This
phenomenon was repeatedly reproducible during
contraction of the abdominal wall muscles.
The diagnosis of SRS was made, and the mechanism
was explained and shown to the patient by
real-time sonography. Reassurance and explanation
were sufficient for this patient, whose symptoms
disappeared without further treatment.
Discussion
Among causes of upper abdominal or lower thoracic
pain, wall disorders are not infrequent. 5–7
They have to be recognized so that correct treatment
can be planned rapidly and unnecessary
explorations can be avoided.
Despite the fact that SRS has been described for
decades in adults 3,4,8 and children, 9,10 it remains
poorly recognized. Classically, the pain occurs in
the upper abdomen or lower chest, above the
costal margin. Although it is often related to
minor trauma, constrained posture, or previous
abdominal surgery, the etiology of SRS remains
unclear, because many patients, such as the
patient in case 3, did not recall any such
event. 3,8,11 Slipping rib syndrome is usually located
on the right side but may also be noticed on
the left or bilaterally. Variation in the intensity of
pain is frequently related to mechanical conditions,
such as coughing or bearing loads in our
cases. Slipping rib syndrome is produced by
impingement of an intercostal nerve between 2
340 J Ultrasound Med 21:339–343, 2002

costal cartilages, secondary to the luxation of an
interchondral articulation. Indeed, contrary to
the first 7 ribs, which are firmly linked to the
sternum by sternocostal joints, the 8th, 9th, and
10th ribs are attached by interchondral weak
joints (Fig. 2). 12,13 According to the original
mechanical description, this allows a rib to slip
behind the rib above it. 1 Our sonographic
observations showed that an overlapping
movement occurred first, followed by a sudden
slipping in depth of the lower rib, with shearing
stress. In a comparative series of 6 volunteers
without symptoms, we had never seen this kind
of movement. Indeed, the contraction of
abdominal wall muscle by the Valsalva maneuver
induced a slow driving of the ribs in the wall,
with preservation of the anatomic relationships
(Fig. 3).
At physical examination, the most common
finding in a case of SRS is tenderness above the
costal margin. During the Valsalva maneuver, it
is possible to palpate the slipping of the rib as
the abdominal muscles contract. The hooking
maneuver described by Heinz and Zavala, 14
Meuwly et al
Figure 1. High-resolution sonographic longitudinal views of the lower right thoracic wall in a patient with SRS, with transverse sections of the seventh
(*) and eighth (#) ribs, which appear as hypoechoic rounded structures. The arrows depict the movements of the ribs. A, At rest, the 2 cartilages lie at
about the same level. B, When rectus muscle (rm) contraction is initiated, the eighth rib moves cranially and overlaps the seventh rib (curved arrow).
C, As the muscle contraction increases, the ribs are slowly pushed down. Suddenly the eighth rib slips along the margin of the seventh rib (arrow). This
movement is felt as a click under the fingers of the examiner. D, At maximal contraction, the 2 ribs are at the same depth, below the rectus muscle.
E, As the contraction decreases, the eighth rib jumps away from the seventh rib (arrow). F, At rest, the ribs return to their initial locations.
Figure 2. Illustration of the anterior view of the sternocostal (SCJ), costochondral
(CCJ), and interchondral (ICJ) joints. Articulations between costal cartilages of the
sixth and seventh, seventh and eighth, and eighth and ninth ribs are plane synovial
joints with a synovial cavity and a weak articular capsule. Articulation between
costal cartilages of the 9th and 10th ribs is fibrous. The position of the transducer,
as used in Figures 1 and 2 is shown (T).
J Ultrasound Med 21:339–343, 2002 341

Slipping Rib Syndrome
Figure 3. High-resolution sonographic longitudinal views of the lower right thoracic wall in a healthy volunteer, with transverse sections of the seventh
(*) and eighth (#) ribs. The arrows depict the movements of the ribs. A, At rest, the 2 cartilages lie at the same level. B, When rectus muscle (rm) contraction
is initiated, the seventh and eighth ribs move down jointly (arrows). C, As the muscle contraction increased, the ribs continue to be pushed
down together (arrows). D, At maximal contraction, the 2 ribs are at the same depth, below the rectus muscle. E, As the contraction decreases, the 2
ribs move up jointly (arrow). F, At rest, the ribs return to their initial locations.
consisting of manual hooking of the costal margin
and anterior stretching, generally produces
a characteristic clicking sound and reproduces
the pain.
To our knowledge, until now there has been no
paraclinical procedure available for assessment
of the diagnosis of the SRS. This lack was reported
by several authors as the main cause of
delayed diagnosis, 2,15 which can result in unnecessary
and sometimes invasive investigations
and prolonged periods of ineffective treatment.
The normal anatomic characteristics of costal
cartilages on sonography has been described
well by Choi et al. 16 They showed that interchondral
joints could be precisely depicted with
sonography and that sequential scanning
allowed an accurate count of them. Furthermore,
we observed that, with high-resolution
sonography of the thoracic wall, the luxation of
the cartilaginous rib can be shown accurately.
Sonography may also exclude other causes of
thoracic pain, such as rib fractures, 17 Tietze syndrome,
18 abscesses, 19 metastases, 20 muscle tears,
pleuritis, and abdominal diseases.
Because SRS usually does not require any treatment
other than comforting and explanation of
the physiopathologic process, real-time sonography
can be used as an informative tool, which
helps the patient understand the mechanism of
the disorder. In 2 cases reported here, the
patients were completely reassured by the explanation
and the real-time visual demonstration of
their slipping rib phenomenon. However, if the
clinical condition does not improve, single or
repeated local anesthetic treatment is usually
curative. 15 In a case of failure of the medical treatment,
as in case 1, surgical removal of the rib may
be necessary. 21
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