DOI:10.2214/AJR.07.3739
AJR 2008; 191:727-729
© American Roentgen Ray Society
Osborne-Cotterill Lesion: An Osseous Defect of the Capitellum Associated with Instability of the Elbow
In-Ho Jeon1,
Ivan D. Micic2,
Nobuyuki Yamamoto3 and
Bernard F. Morrey3
1 Department of Orthopaedic Surgery, School of Medicine, Kyungpook National
University, 50, Samduk, Chung-gu, Daegu, Korea 700-721.
2 Clinic for Orthopaedic Surgery and Traumatology, Faculty of Medicine, Nis,
Serbia.
3 Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN.
Received January 28, 2008;
accepted after revision March 26, 2008.
Address correspondence to I. H. Jeon
(jeonchoi{at}chol.com).
Abstract
OBJECTIVE. Posterolateral rotatory instability of the elbow is a
diagnosis largely made by clinical examination; no relevant radiographic signs
have been reported. We have seen four patients with an osseous defect and
detachment of a fragment of bone in the posterolateral margin of the
capitellum. These patients had chronic posterolateral rotatory instability of
the elbow.
CONCLUSION. An osseous defect of the posterolateral corner of the
capitellum is an uncommon finding that in each instance was associated with
chronic posterolateral rotatory instability of the elbow. We termed this
lesion the "Osborne-Cotterill lesion." We report our findings in
these patients; when this lesion is diagnosed, clinicians should consider
posterolateral rotatory instability.
Keywords: capitellum • elbow • osteochondral defect • posterolateral rotatory instability
Introduction
Posterolateral rotatory instability of the elbow is the most common pattern
of instability [1,
2], the pathology of which has
been well described, as has the corrective surgical reconstruction. Studies of
the anatomy, mechanism of injury, and clinical presentation have documented
lateral ulnar collateral ligament failure as the cause
[2,
3]. Recurrent posterolateral
dislocation usually occurs after simple traumatic dislocation, but associated
intraarticular fracture may occur.
In 1966, Osborne and Cotterill
[4] reported recurrent
dislocation of the elbow and described "an osteochondral fracture in the
posterolateral margin of the capitellum with or without a crater or
shovel-like defect in the radial head" as the main abnormality of this
condition. They did not recognize the essential ligamentous pathology to the
lateral ulnar collateral ligament.
We have treated four patients with an osseous lesion associated with
detachment of a bone fragment occurring in the posterolateral margin of the
capitellum in chronic posterolateral rotatory instability of the elbow. We
suggest terming this injury the "Osborne-Cotterill lesion" and
believe it is indicative of posterolateral rotatory instability of the
elbow.
Materials and Methods
We retrospectively reviewed the records of patients with posterolateral
rotatory instability of the elbow admitted to our institutionbetween 2003 and
2007 and found four patients in whom an osseous defect at the posterolateral
aspect of the capitellum was detected on radiographic assessment.
Three patients were men and one was a woman; their average age was 22 years
(range, 18–25 years). All patients were initially referred for elbow
pain and intermittent painful subluxation of several months' duration (range,
3–10 months). All had sustained a dislocation of the elbow 24–60
months before the present symptoms developed. All patients underwent
radiography and CT of the elbow with 3D reconstruction images, and one patient
underwent MRI preoperatively (Table
1). All patients underwent a reconstruction procedure for the
elbow instability, two within 3 years and two within 4 years after injury.
Results
Three patients sustained elbow dislocation after a fall from a significant
height and one from martial arts combat. All were immobilized with a splint
for 3–4 weeks after closed reduction. At referral, all patients had
symptomatic instability. The pivot shift test specific for posterolateral
rotatory instability was positive only when the patient was under general
anesthesia.
Radiographs in three patients showed a bone fragment detached from the
posterolateral aspect of the lateral epicondyle. In one patient, the osseous
fragment had apparently resorbed because no fragment was visualized on the
radiograph.
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Fig. 1A —23-year-old man who had intermittent painful subluxation of
elbow during military training. He had a history of dislocation of his elbow 4
years earlier and had splint immobilization for 3–4 weeks. Radiographs
show nonunited lateral condyle fracture fragment posterolateral to radial
head, which lost its normal contact with capitellum.
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Fig. 1B —23-year-old man who had intermittent painful subluxation of
elbow during military training. He had a history of dislocation of his elbow 4
years earlier and had splint immobilization for 3–4 weeks. Radiographs
show nonunited lateral condyle fracture fragment posterolateral to radial
head, which lost its normal contact with capitellum.
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Fig. 1C —23-year-old man who had intermittent painful subluxation of
elbow during military training. He had a history of dislocation of his elbow 4
years earlier and had splint immobilization for 3–4 weeks. Radiographs
show nonunited lateral condyle fracture fragment posterolateral to radial
head, which lost its normal contact with capitellum.
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Fig. 1D —23-year-old man who had intermittent painful subluxation of
elbow during military training. He had a history of dislocation of his elbow 4
years earlier and had splint immobilization for 3–4 weeks. Radiographs
show nonunited lateral condyle fracture fragment posterolateral to radial
head, which lost its normal contact with capitellum.
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Fig. 1E —23-year-old man who had intermittent painful subluxation of
elbow during military training. He had a history of dislocation of his elbow 4
years earlier and had splint immobilization for 3–4 weeks.
Reconstructions from CT images show bone defect in posterolateral aspect of
joint that involved distal and lateral corners of capitellum.
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Fig. 1F —23-year-old man who had intermittent painful subluxation of
elbow during military training. He had a history of dislocation of his elbow 4
years earlier and had splint immobilization for 3–4 weeks.
Reconstructions from CT images show bone defect in posterolateral aspect of
joint that involved distal and lateral corners of capitellum.
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CT was performed in all patients and showed a shear fracture fragment off
the posterolateral capitellum, including bone fragments from the site of the
humeral attach ment of the posterolateral capsule. A depressed fracture
involving the postero lateral part of the lateral condyle and capitellum was
the predominant observation. The radial head was enlarged compared with the
opposite side.
Three-dimensional reconstruction CT was performed in all patients and
showed shell-like bone fragments of various sizes (average, 12 x 14 mm)
posterolateral to the radio capitellar joint. All lesions violated the
posteroinferior aspect of the capitellum, thereby providing poor coverage of
the radial head by the capitellum in extension (Fig.
1A,
1B,
1C,
1D,
1E,
1F). In three patients, the
radial head was relatively enlarged compared with the opposite side, and a
small fracture at the anterior margin of the head was seen in one patient.
Discussion
Posterolateral rotatory instability of the elbow is an entity that was
described at the Mayo Clinic in 1991
[1]. This instability was shown
to be caused by insufficiency of the lateral collateral ligament complex
[2,
5]. Most series in the
literature have a documented posttraumatic or iatrogenic origin
[6]. Ligamentous insufficiency
typically results in multiple episodes of instability during which the ulna
and radius rotate externally and then posteriorly as the forearm displaces
into a valgus position. Symptoms range from catching or locking of the elbow
to subjective instability to frank recurrent dislocation.
The diagnosis of posterolateral rotatory instability can be delayed if it
is not suspected clinically and explicitly investigated. When in doubt, the
elbow should be examined under fluoroscopic control and occasionally with the
patient under anesthesia.
Baseline imaging has not been described as helpful in the past.
Confirmation of a tear of the lateral ulnar collateral ligament of the elbow
on MRI can be complicated and sometimes misleading
[7,
8] as a result of the relative
lack of understanding of the nature and complexity of the lateral ligament
complex. In 1985, Morrey and An
[3] first described the
specialized band originating from the humerus and inserting on the tubercle of
the supinator crest. They termed the structure the "lateral ulnar col
lateral ligament." However, this band was not recognized in all
dissections [3]. Subsequently,
in an MRI study by Terada et al.
[9], the lateral ulnar
collateral ligament was identified in only 50% of asymptomatic
cases—hence the value of this current observation of an easily
identified osseous lesion. On CT, a depressed fracture involving the posterior
lateral part of the lateral condyle and capitellum has been the predominant
observation. We believe the value of CT in this condition is investigating the
fragment size and exact location.
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Fig. 2 —Proposed pathoanatomy of osteochondral defect we call
"Osborne-Cotterill lesion." Drawings show normal articulation of
radiocapitellar joint (A), hyperextension of elbow joint loading shear
force at posterior capitellum (B), and radial head engaged in bone
defect with injury to lateral ulnar collateral ligament (C).
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Osborne and Cotterill [4]
first described a capitellar defect in recurrent elbow dislocation as similar
to the glenoid defect (bony Bankart lesion) observed in recurrent shoulder
dislocation. Detachment of the capsulo ligamentous structure with
osteochondral defect of the glenoid observed in recurrent shoulder dislocation
is analogous to the osseous defect occurring at the posterolateral capitellum,
which is associated with posterolateral rotatory instability of the elbow
(Fig. 2). Although it was not
mentioned in the original article
[4], we found an enlarged
radial head in the affected elbow that we termed the "caput magna
radii." We were unable to explain the exact pathology of this phenomena,
which has been reported after radial head fracture during growth and is
somewhat similar to the caput magnum in dysplastic hip joints. In our series,
all patients sustained the dislocation between the ages of 18 and 25 years.
One patient underwent MRI postoperatively that showed reattachment of the
graft collateral ligament complex and restoration of the capitellar contour.
MRI can be used for investigation of associated ligamentous injuries and of
the osteochondral nature of the lesion.
We suggest calling this abnormality an Osborne-Cotterill lesion because
those authors were the first to describe the lesion. However, this precise
lesion is not truly a nonunited lateral epicondyle, as they had described, but
rather represents a shear or depression fracture of the capitellum and the
lateral condyle.
Ours is the first description of an osseous lesion distinguishable on
radiographs that show the full abnormality of the posterolateral rotatory
instability. Knowledge of this Osborne-Cotterill lesion can be important when
diagnosing patients with posterolateral rotatory instability. The surgical and
preoperative implications of this finding are yet to be determined.
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Abstract
Introduction
