AJR 2005; 185:397-399
© American Roentgen Ray Society
MRI, Arthroscopy, and Histologic Observations of an Annular Ligament Causing Painful Snapping of the Elbow Joint
Guo-Shu Huang1,
Chian-Her Lee2,
Herng-Sheng Lee3 and
Cheng-Yu Chen1
1 Department of Radiology, Tri-Service General Hospital, National Defense
Medical Center, 325, Section 2, Cheng-Kung Rd., Neihu 114, Taipei, Taiwan,
Republic of China.
2 Department of Orthopedic Surgery, Tri-Service General Hospital, National
Defense Medical Center, Taipei, Taiwan, Republic of China.
3 Department of Pathology, Tri-Service General Hospital, National Defense
Medical Center, Taipei, Taiwan, Republic of China.
Received August 2, 2004;
accepted after revision September 25, 2004.
Address correspondence to G.-S. Huang
(gsh5{at}seed.net.tw).
Introduction
Snapping of the elbow joint is a pathologic condition in which an
interposed or impinged tissue in the elbow joint clicks when the elbow is
flexed and extended. The causes of snapping elbow have been attributed to
intraarticular loose bodies, instability, synovial plicae
[1], and a torn or loose
annular ligament [2]. Diagnosis
and monitoring of treatment regimens is most commonly done using arthroscopy
[1].
The noninvasive nature and internal resolution power of MRI make it an
attractive technology to evaluate internal derangements of joints. However, no
reports to our knowledge have shown the value and usefulness of MRI in
identifying the causes and interposed tissues for snapping elbow. We report a
case of painful snapping of the elbow joint caused by a torn or loose annular
ligament. MRI clearly showed the interposed tissue of a loose annular ligament
in the radiocapitellar joint. The MRI findings correlated well with
arthroscopic and histologic data.
Case Report
A 21-year-old man came to our orthopedic surgery outpatient clinic for
relief of pain and a snapping sensation in the lateral aspect of his right
elbow. He reported that he first became aware of the clicking sound in the
right elbow during flexion and extension some years previously, when he was in
junior high school. The snapping sensation had persisted over the intervening
years. Two years before his admission, he began to experience pain in the
lateral aspect of the right elbow. The patient then visited the local medical
clinic for help. Lateral epicondylitis was diagnosed. The pain persisted and
was not relieved by regular oral doses of nonsteroidal antiinflammatory drugs.
Although he had played baseball occasionally and recreationally since
elementary school, the patient was not a pitcher or a participant in an
organized league. This activity had ceased since the development of the
lateral elbow pain.
The patient was right-handed. No history of trauma to the right elbow was
reported. Physical examination confirmed a snapping sound in the right elbow
that occurred when the elbow was in pronation and passively flexed 110°.
The snapping reoccurred when the pronated elbow was passively extended to
70°. No instability or limitation of the range of motion of the right
elbow joint was present. Mild tenderness without redness or swelling of the
lateral aspect of the right elbow was present. Anteroposterior and lateral
radiographs of the right elbow were normal. MRI examination showed a
meniscuslike tissue of low signal intensity outlined by a small effusion of
high signal intensity in the anterolateral aspect of the radiocapitellar joint
and interposed between the radial head and capitellum on T2-weighted coronal
(Fig. 1A) and sagittal
(Fig. 1B) images. The
meniscuslike tissue, which was attached to the capsule at its periphery,
showed a region of high signal intensity considered to be myxoid change within
the tissue substance. The interposed meniscuslike tissue was like a thickened
synovial fold. A slightly wavy ligamentlike tissue of low signal intensity was
present around the anterolateral aspect of the radial head and neck and in the
corresponding course of the annular ligament (Figs.
1A and
1B). This tissue was positioned
close to the capsule and the outer margin of the interposed meniscuslike
tissue.
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Fig. 1A —21-year-old man with annular ligament causing painful
snapping of elbow joint. Coronal fat-suppression fast-spin-echo T2-weighted
(TR/TE, 2,900/99) (A) and sagittal spin-echo T2-weighted (1,800/80)
(B) MR images show meniscuslike tissue (large arrow) of torn
or loose annular ligament with low signal intensity interposed between radial
head and capitellum in periphery of anterolateral aspect of radiocapitellar
joint. Small region of high signal intensity is considered myxoid change
within tissue substance. Annular ligament (small arrows) is torn or
loose and presents wavy appearance, closing to outer margin of interposed
meniscuslike tissue. Note chondral defects of radial head and capitellum, with
subchondral marrow edema of radial head and mild sclerosis of capitellum.
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Fig. 1B —21-year-old man with annular ligament causing painful
snapping of elbow joint. Coronal fat-suppression fast-spin-echo T2-weighted
(TR/TE, 2,900/99) (A) and sagittal spin-echo T2-weighted (1,800/80)
(B) MR images show meniscuslike tissue (large arrow) of torn
or loose annular ligament with low signal intensity interposed between radial
head and capitellum in periphery of anterolateral aspect of radiocapitellar
joint. Small region of high signal intensity is considered myxoid change
within tissue substance. Annular ligament (small arrows) is torn or
loose and presents wavy appearance, closing to outer margin of interposed
meniscuslike tissue. Note chondral defects of radial head and capitellum, with
subchondral marrow edema of radial head and mild sclerosis of capitellum.
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At the time of the MRI examination, a torn or loose annular ligament was
thought to be present. In addition, on T2-weighted MRI, a kissing lesion of
radiocapitellar cartilage was identified. The lesion displayed chondral
defects of the radial head and capitellum, with a marrow edema of the radial
head and mild sclerosis of the capitellar subchondral bone (Figs.
1A and
1B). The interposed
meniscus-like tissue was not conspicuously shown on T1-weighted MRI (images
not shown).
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Fig. 1C —21-year-old man with annular ligament causing painful
snapping of elbow joint. Images obtained on arthroscopic examination show
meniscuslike tissue (arrow) of torn or loose annular ligament
slipping out of (C) and over (D) radial head with visible
snapping in elbow flexed to 110° and extended to 70°, respectively. RH
= radial head, HC = humeral capitellum.
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Fig. 1D —21-year-old man with annular ligament causing painful
snapping of elbow joint. Images obtained on arthroscopic examination show
meniscuslike tissue (arrow) of torn or loose annular ligament
slipping out of (C) and over (D) radial head with visible
snapping in elbow flexed to 110° and extended to 70°, respectively. RH
= radial head, HC = humeral capitellum.
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Arthroscopy was performed from the posterolateral approach. The examination
showed a white, hard meniscuslike band (Figs.
1C and
1D) attached to the capsule.
The band was located in the anterolateral aspect of the radiocapitellar joint
and was interposed between the radial head and capitellum.
At surgery, intraoperative physical examination of the right elbow joint
verified that the snapping originated from the interposed tissue slipping out
of the radiocapitellar joint when the elbow was passively flexed to 110°
and when the interposed tissue fell into the radiocapitellar joint when the
elbow was passively extended to 70°. The interposed meniscuslike tissue
was excised. The associated erosions and defects of the cartilage of the
radial head and capitellum were found and shaved. No intraarticular bodies
were found. Histologic examination of the removed tissue showed a ligamentous
tissue containing oriented collagen fibers and focal regions of myxoid change
(Figs. 1E and
1F). No fibrocartilage or
chondroid component was present within the removed tissue. No synovial layer
on the surface of the removed tissue was found. Based on the MRI findings,
arthroscopy, and histology, the interposed meniscuslike tissue in the
radiocapitellar joint was thought to be a torn or loose annular ligament.
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Fig. 1E —21-year-old man with annular ligament causing painful
snapping of elbow joint. Photomicrograph of tissue removed from right elbow
joint. Light microscopic examination (H and E, x 200) reveals ligament
structure containing oriented collagen fibers consistent with annular
ligament. Note focal regions of myxoid change (arrow). No
fibrocartilage or chondroid metaplasia was found.
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Fig. 1F —21-year-old man with annular ligament causing painful
snapping of elbow joint. Examination of similarly prepared tissue (x 40)
reveals absence of synovial layer on surface of removed tissue.
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After surgery, the snapping sensation of the right elbow joint immediately
disappeared, and the lateral elbow pain was improved at an 8-month follow-up
examination.
Discussion
Snapping of the elbow joint can be painful, inconvenient, and persistent.
The condition more commonly occurs laterally than medially
[1,
2]. Painful lateral elbow
caused by elbow snapping can be misdiagnosed as lateral epicondylitis or
tennis elbow, since many clinicians are not familiar with this pathologic
condition [1].
Snapping of the elbow joint has been attributed to the interposition of a
lateral synovial fold [1] and a
torn or loose annular ligament in the radiocapitellar joint
[2]. The fold is a remnant of
embryonic septa, similar to that in the knee joint. Chronic impingement and
irritation of the interposed tissue during elbow motion leads to inflammation,
fibrosis, degeneration, and hardening of the synovial fold and the annular
ligament, which is a prelude to the snapping and pain that occurs on flexion
and extension [3].
Lateral snapping of the elbow is thought to arise from a torn or loose
annular ligament, as initially documented in one case by Wrightman
[4]. In that case, a torn
annular ligament displaced in the radiocapitellar joint, causing a visible
click in the lateral part of the elbow. The author observed that when the
elbow extended, tightening of the anterior capsule tended to pull the annular
ligament proximally, and this caused the separated band to slip over and cover
the radial head. When the elbow flexed, the separated band slipped distally
and uncovered the radial head. In our case, intraoperative examination
confirmed that the snapping arose from slippage of the ligamentous band out of
the radial head at elbow flexion and from the ligamentous band slipping over
the radial head at extension.
Imaging evaluation used to establish the causes of snapping elbow has been
thought to be of limited value
[1,
2]. The use of MRI in this
regard has not been widely considered
[1,
2]. In one report
[1], MRI performed on six
patients with synovial plicae causing painful snapping elbow was interpreted
as normal in five patients and showed mild edema of the annular ligament in
one patient. Another report [2]
documented two patients with snapping annular ligament of the elbow joint in
which MRI showed no abnormal findings in one case and only slight effusion in
the other case. The underestimation of MRI in demonstrating the snapping
tissue may have been due to inadequate joint effusion outlining the snapping
tissue in the radiocapitellar joint. In addition, unfamiliarity with this
clinical entity may have led the radiologists to misdiagnose the nature of the
images. In this patient, the snapping annular ligament over the radial head
delineated by joint effusion was clearly identified on T2-weighted coronal and
sagittal images. MRI arthrography would be helpful for patients with no
obvious effusion in the elbow joint. Associated chondral lesions of the radial
head and capitellum may occur and have been described in patients with
snapping synovial fold [1].
T2-weighted MRI identified the chondral defects and bone marrow abnormalities
of the radial head and capitellum.
In conclusion, a torn or loose annular ligament as a cause of painful
snapping of the lateral elbow joint has been described. Familiarity with this
entity may obviate the misdiagnosis in patients with lateral elbow pain. In
our experience, MRI with T2-weighted sequence or MRI arthrography is useful in
identifying the snapping annular ligament and other interposed tissue in the
elbow joint.
References
- Antuna SA, O'Driscoll SW. Snapping plicae associated with
radiocapitellar chondromalacia. Arthroscopy2001; 17:491
–495[Medline]
- Aoki M, Okamura K, Yamashita T. Snapping annular ligament of the
elbow joint in the throwing arms of young brothers.
Arthroscopy 2003;19
: E4–E7
- Akagi M, Nakamura T. Snapping elbow caused by the synovial fold in
the radio-humeral joint. J Shoulder Elbow Surg1999; 7:427
–429
- Wrightman JAK. Clicking elbow from a torn annular ligament: report
of a case. J Bone Joint Surg Br 1963;45
: 380–381
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Introduction
Case Report
