DOI:10.2214/AJR.07.3705
AJR 2008; 190:W380-W381
© American Roentgen Ray Society
Reply
Liem T. Bui-Mansfield1 and
Seth D. O'Brien2
1 San Antonio Uniformed Services Health Education Consortium, Brooke Army
Medical Center, Fort Sam Houston, TX, Wake Forest University, Winston-Salem,
NC, Uniformed Services University of the Health Sciences, Bethesda,
MD
2 San Antonio Uniformed Services Health Education Consortium, Brooke Army
Medical Center, Fort Sam Houston, TX
WEB—This is a Web exclusive article.
The opinions and assertions contained herein are those of the authors and
should not be construed as official or as representing the opinions of the
Department of the Army or the Department of Defense.
We thank Dr. Kassarjian [1]
for his interest in our article
[2]. We agree that high signal
intensity within muscle is a nonspecific finding with a long differential
[3]. Dr. Kassarjian offered an
interesting explanation for the high signal within the quadratus femoris
muscle in patients presenting with chronic symptoms: impingement of the muscle
between the ischial tuberosity and lesser trochanter. Although this is a
potential cause for the muscle edema, we and our orthopedic colleagues are not
familiar with this diagnosis.

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Fig. 1A —43-year-old woman with partial tear of left quadratus femoris
muscle. Axial T2-weighted fat-suppressed image shows edema and small focal
fluid-hemorrhage within muscle belly of left quadratus femoris muscle located
between ischial tuberosity (i) and lesser trochanter (t).
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Fig. 1B —43-year-old woman with partial tear of left quadratus femoris
muscle. Sagittal proton-density fat-suppressed image shows edema within muscle
belly of quadratus femoris muscle posterior to lesser trochanter (t).
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Fig. 1C —43-year-old woman with partial tear of left quadratus femoris
muscle. Axial T2-weighted fat-suppressed image obtained 13 months after
A and B shows significant decrease in muscle edema
(arrow) within left quadratus femoris muscle.
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Fig. 1D —43-year-old woman with partial tear of left quadratus femoris
muscle. Sagittal proton-density fat-suppressed image obtained 13 months after
A and B shows minimal muscle edema posterior to lesser
trochanter (t).
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Fig. 2C —35-year-old woman with right hip pain. Axial T2-weighted
fat-suppressed image obtained 11 months after A and B shows no
muscle edema between lesser trochanter (t) and ischial tuberosity (i).
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We conducted a search on PubMed and could not find a single article on this
topic [4]. Consequently, we are
not aware of the clinical or imaging criteria for the diagnosis of quadratus
femoris muscle impingement. In contrast, quadratus femoris muscle tear or
strain has been reported in sports medicine literature
[5-8].
None of our cases had a narrow space between the ischial tuberosity and lesser
trochanter as depicted in Figures
2A,
2B,
2C and
2D of Dr. Kassarjian's letter
[1].
Finally, after the publication of our article
[2], two of our patients had
follow-up MR examinations that showed decreased edema within the muscle,
suggestive of healing (Figs.
1A,
1B,
1C,
1D,
2A,
2B,
2C and
2D). Because impingement of the
quadratus femoris muscle is a chronic process, we would expect the edema to be
the same or worse with time. Without surgical correlation or clinical criteria
for the diagnosis of quadratus femoris muscle impingement, it would be
impossible to prove definitively whether our cases are due to muscle tear or
impingement.
We agree with Dr. Kassarjian
[1] that if a patient presents
acutely, quadratus femoris muscle tear is more likely than impingement.
Dynamic MRI may also be helpful to distinguish the two causes. In either case,
we believe that conservative therapy is still the treatment of choice. Again,
we appreciate the writer for proposing an interesting potential cause for
muscle edema within the quadratus femoris muscle.
References
- Kassarjian A. Signal abnormalities in the quadratus femoris muscle:
tear or impingement? (letter) AJR 2008;190
:[web] W379[Free Full Text]
- O'Brien SD, Bui-Mansfield LT. MRI of quadratus femoris muscle tear:
another cause of hip pain. AJR 2007;189
: 1185-1189[Abstract/Free Full Text]
- May DA, Disler DG, Jones EA, Balkissoon AA, Manaster BJ. Abnormal
signal intensity in skeletal muscle at MR imaging: patterns, pearls, and
pitfalls. RadioGraphics 2000;20
[spec no]:S295
-S315[Abstract/Free Full Text]
- PubMed Website.
www.ncbi.nlm.nih.gov/sites/entrez.
Accessed December 31, 2007
- Klinkert P Jr, Porte RJ, de Rooij TP, de Vries AC. Quadratus
femoris tendinitis as a cause of groin pain. Br J Sports
Med 1997; 31:348
-349[Free Full Text]
- Peltola K, Heinonen OJ, Orava S, Mattila K. Quadratus femoris
muscle tear: an uncommon cause for radiating gluteal pain. Clin J
Sport Med 1999; 9:228
-230[Medline]
- Willick SE, Lazarus M, Press JM. Quadratus femoris muscle strain.
Clin J Sport Med 2002;12
: 130-131[CrossRef][Medline]
- Askling CM, Tengvar M, Saartok T, Thorstensson A. Acute first-time
hamstring strains during slow-speed stretching: clinical, magnetic resonance
imaging, and recovery characteristics. Am J Sports Med2007; 35:1716
-1724[Abstract/Free Full Text]

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