DOI:10.2214/AJR.07.3027
AJR 2008; 190:595-598
© American Roentgen Ray Society
Avulsion of the Medial Epicondyle After Ulnar Collateral Ligament Reconstruction: Imaging of a Rare Throwing Injury
Martin L. Schwartz1,
D. Dean Thornton1,
Matthew C. Larrison1,2,
E. Lyle Cain3,
Don G. Aaron3,4,
Kevin E. Wilk5 and
James R. Andrews3
1 Radiology Associates of Birmingham, 2090 Columbiana Rd., Ste. 4400,
Birmingham, AL 35216.
2 Present address: Department of Radiology, University of Alabama at Birmingham,
Birmingham, AL.
3 Andrews Sports Medicine and Orthopaedic Center, Birmingham, AL.
4 Present address: Southeastern Orthopedic Center, Statesboro, GA.
5 Champion Sports Medicine, American Sports Medicine Institute, Birmingham,
AL.
Received August 15, 2007;
accepted after revision September 27, 2007.
Address correspondence to D. D. Thornton.
Abstract
OBJECTIVE. The objective of this article is to report and describe
the clinical and imaging features of an avulsion fracture of the medial
epicondyle after ulnar collateral ligament (UCL) reconstruction.
CONCLUSION. Avulsion fracture of the medial epicondyle is a rare
complication of UCL reconstruction with distinct radiographic and MRI
findings.
Keywords: elbow pain • ligament reconstruction • sports medicine • throwing injuries • ulnar collateral ligament
Introduction
Medial elbow pain is a common symptom in the throwing athlete. The tensile
strength of the ulnar collateral ligament (UCL) is often exceeded by the
thrower especially at the elite (i.e., college and professional) levels of
competition. Due to repetitive microtrauma, the UCL can weaken and can
ultimately tear, causing a disabling injury to the athlete. The treatment of
choice in these cases is UCL reconstruction using graft material from either
the palmaris longus or gracilis tendon. After extensive rehabilitation, many
of these players are able to return to the same level of activity as before
their injury.
There are several techniques for UCL reconstruction, all of which involve
drilling tunnels in the medial epicondyle of the humerus and in the proximal
ulna. Jobe et al. [1] described
the first UCL reconstruction, the so-called "Tommy John surgery,"
named after the first pitcher to undergo the procedure. Their technique was to
detach the common flexor muscle mass and transpose the ulnar nerve in a
submuscular fashion. Then, three tunnels were drilled into the medial
epicondyle and the graft was placed in a figure-of-eight fashion. Ulnar nerve
complications were common in this patient group with several requiring a
second surgery for decompression of the nerve
[2].
Smith et al. [3] modified
the technique proposed by Jobe et al.
[1] by splitting the flexor
muscle mass, thereby avoiding ulnar nerve transposition. Complications were
decreased and still related to the ulnar nerve but were transient in all
patients. Eighty-two percent of elite throwers returned to the same level of
play 2 years after surgery. Azar et al.
[4] modified the technique
proposed by Jobe et al. by retracting the flexor carpi ulnaris anteriorly and
by performing a subcutaneous ulnar nerve transposition. They reported that 79%
of the patients treated with their modified technique returned to the same
level of the sport as before the surgery. Only one patient had transient ulnar
nerve changes.
Rohrbough et al. [5] used a
muscle-splitting technique called the "docking procedure." Instead
of a figure-of-eight graft position, the graft is placed in a triangular
configuration with a single humeral tunnel. Using this technique, they
reported a 92% success rate in patients returning to the preinjury level of
play for at least 1 year [5].
Paletta and Wright [6] reported
a modification to the docking technique using a four-stranded graft for
reconstruction instead of a double-stranded graft. They also reported 92%
success in returning patients to their previous level of competition.
As with any surgical procedure, potential complications are associated with
UCL reconstruction. Most of the reported complications in this patient
population are related to the ulnar nerve and are usually transient. One
report in the literature describes a baseball player with a postoperative
fracture through the ulnar tunnel 7 months after UCL reconstruction while he
was taking batting practice
[5]. A second report involved a
patient with a stress fracture of the ulnar bone bridge 14 months after UCL
reconstruction and after returning to a full schedule of pitching
[6]. To date, we have found no
reports in the literature about avulsion of the medial epicondyle after UCL
reconstruction. We present the imaging findings from seven throwing athletes
with avulsion fracture of the medial epicondyle after UCL reconstruction.
Materials and Methods
The charts of five professional and two collegiate throwing athletes
(baseball players) were retrospectively reviewed. These patients had
previously undergone UCL reconstruction and subsequently presented to the
orthopedic clinic complaining of disabling medial elbow pain. All of the
subjects were male and ranged in age from 22 to 35 years (mean age, 27 years).
The players included five pitchers, one catcher, and one infielder. One
subject, a pitcher, had undergone a second UCL reconstruction before his
avulsion fracture.
The method used for reconstruction in six of the patients was a modified
Jobe technique using a figure-of-eight fixation in the medial epicondyle with
ulnar nerve transposition. This technique utilizes two convergent humeral
tunnels starting at the superior medial epicondyle and ending in a single
tunnel at the anteroinferior margin of the epicondyle
[4]. A palmaris longus tendon
graft was used in three patients, and a gracilis tendon graft was used in
three others. The seventh patient underwent reconstruction at a different
institution; the surgical technique and graft type could not be determined.
Six throwers were right-handed; one was left-handed. The time from
reconstruction to avulsion of the medial epicondyle ranged from 6 weeks to 13
months (mean, 9.7 months). All of the players underwent open reduction and
internal fixation (ORIF) of the epicondylar fracture except one who elected to
be splinted.
After a thorough physical examination of each patient was performed,
conventional and stress radiographs of the injured elbow were obtained in each
individual. Stress radiographs were obtained with the application of 15 kPa of
force using a Telos device (Austin and Associates). A postfracture MRI
examination was performed on one thrower at our institution to determine
whether the UCL graft was still attached to the avulsed medial epicondyle. Two
players had postfracture MRI examinations at outside institutions. All
patients who underwent ORIF of the medial epicondylar fracture underwent
postoperative radiography.
The MRI examinations at our institution were performed on a 3-T system
(Signa Excite, GE Healthcare). Sequences included axial and coronal
T1-weighted spin-echo images (TR range/TE, 600–817/11; field of view,
140 mm; matrix size, 192 x 192; slice thickness, 3 mm; gap, 1 mm); and
axial, coronal, and sagittal T2-weighted fatsaturation images (TR/TE,
3,000/48; field of view, 140 mm; matrix size, 192 x 192; slice
thickness, 3 mm; gap, 1 mm).
Results
Seven patients with a history of UCL reconstruction presented with
debilitating medial elbow pain after injury
(Table 1). Clinical and imaging
evaluations revealed medial epicondyle avulsion fracture in each subject. Six
of the seven underwent successful reattachment of the medial epicondyle
fragment; the seventh patient elected to have nonoperative treatment with
placement of his elbow in a splint. The radiographic and MRI findings in one
individual are presented beginning with his original UCL reconstruction until
ORIF of the avulsed medial epicondyle (Fig.
1A,
1B,
1C,
1D,
1E).
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Fig. 1A —21-year-old male right-handed college baseball pitcher with
medial elbow pain (patient 7 in Table
1). Anteroposterior (AP) radiograph of right elbow shows expected
immediate postoperative appearance of ulnar collateral ligament (UCL)
reconstruction. Note vertically oriented humeral tunnel (arrow) at
base of medial epicondyle.
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Fig. 1B —21-year-old male right-handed college baseball pitcher with
medial elbow pain (patient 7 in Table
1). Twelve months after UCL reconstruction, patient again
presented with severe medial elbow pain after throwing. AP radiograph shows
avulsion fracture of medial epicondyle (arrow) up to humeral
tunnel.
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Fig. 1C —21-year-old male right-handed college baseball pitcher with
medial elbow pain (patient 7 in Table
1). Coronal T2-weighted fat-suppressed MR image shows moderately
displaced medial epicondyle avulsion fracture (curved arrow)
involving humeral tunnel. UCL graft (straight arrow) contains
increased signal but remains intact and attached to avulsed fragment.
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Radiographs were obtained of all players and showed variability in the
appearance of the medial epicondyle avulsion fractures. The severity of the
fractures ranged from displacement of the entire medial epicondyle to avulsion
of a small fragment. All of the patients exhibited some degree of medial
instability as seen on stress radiography, which showed widening of the medial
joint space (Fig. 2A,
2B). The degree of fracture
displacement varied from marked to minimal. The more displaced fracture
fragments tended to exhibit some degree of rotation as well
(Fig. 1B).
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Fig. 2A —22-year-old male baseball player with medial elbow pain 2.5
months after ulnar collateral ligament reconstruction (patient 1 in
Table 1). Stress radiographs
without (A) and with (B) 15 kPa of force depict avulsion
fracture of medial epicondyle (arrow, A). Medial instability
is shown by marked widening of medial joint space (double arrow,
B) with valgus stress. Stress view also shows additional displacement
of medial epicondyle fragment (curved arrow, B).
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Fig. 2B —22-year-old male baseball player with medial elbow pain 2.5
months after ulnar collateral ligament reconstruction (patient 1 in
Table 1). Stress radiographs
without (A) and with (B) 15 kPa of force depict avulsion
fracture of medial epicondyle (arrow, A). Medial instability
is shown by marked widening of medial joint space (double arrow,
B) with valgus stress. Stress view also shows additional displacement
of medial epicondyle fragment (curved arrow, B).
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MRI was performed in three patients. On MRI, we noted that the fractures
occurred at the base of the medial epicondyle, extending to the medial
epicondylar UCL graft tunnels and always involving the convergent distal
tunnel. The fractures were angulated from posterolateral to anteromedial as
seen on axial images (Figs. 1D
and 3A). The fragments were
displaced anteromedially in two cases and medially in one case. In one patient
in our series, the UCL graft contained increased signal on T1- and T2-weighted
images but appeared otherwise intact (Fig.
1A,
1B,
1C,
1D,
1E). In another patient, the
UCL graft appeared thickened with increased signal in the proximal portion of
the graft (Fig. 3B) but was
found to be intact at surgery. In fact, none of the patients in our series
required UCL reconstruction as a result of the avulsion fracture.
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Fig. 3A —29-year-old male baseball player with avulsion of medial
epicondyle after ulnar collateral ligament (UCL) reconstruction (patient 2 in
Table 1). Axial T1-weighted MR
image shows avulsed fragment (circle) and its relationship to humeral
tunnel (arrow). Fragment is displaced anteromedially.
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Fig. 3B —29-year-old male baseball player with avulsion of medial
epicondyle after ulnar collateral ligament (UCL) reconstruction (patient 2 in
Table 1). Coronal T1-weighted
MR image. Despite its irregular, heterogeneous appearance, UCL graft
(arrows) and its attachment to avulsed fragment (circle)
were intact at surgery.
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All but one of the avulsion injuries occurred as a result of throwing. The
exception was in a patient (patient 4 in
Table 1) 6 weeks (1.5 months)
after UCL reconstruction who grabbed his falling child resulting in the
avulsion fracture. One patient (patient 1 in
Table 1) started throwing
before receiving medical clearance; his injury occurred 2.5 months after UCL
reconstruction. The remaining players sustained injury between 6.5 and 13
months after reconstruction. Three of six individuals returned to play at or
above the level they were playing when the avulsion occurred. One pitcher
underwent surgery 4 months before we wrote this article and is undergoing
postoperative rehabilitation.
None of the patients in our series suffered ulnar nerve injury. It is of
interest that the first three patients in our series underwent UCL
reconstruction using palmaris longus tendon autografts, and three of the last
four patients had gracilis tendon autografts. The seventh player had surgery
at an outside institution, and the type of graft could not be determined. The
appearance of the avulsion fracture did not differ relative to the UCL graft
type.
Discussion
We have presented the imaging findings from seven throwing athletes with
avulsion of the medial epicondyle after UCL reconstruction. This injury is a
rare postoperative complication that has not been described previously in the
radiology or orthopedics literature, to our knowledge.
Of nearly 1,100 patients who have undergone UCL reconstruction at our
institution, only six cases of medial epicondyle fracture have occurred. The
seventh player in our series had reconstruction at an outside institution. At
least half of these throwers have returned to the same level of play after
ORIF of the fracture fragment. The findings can be adequately shown using
conventional and stress radiography, but MRI can be helpful in evaluating the
fracture and the UCL graft and its attachment to the avulsed fragment. The
site of the fracture consistently involved the humeral tunnel or tunnels of
the UCL reconstruction, which can act as a stress riser.
Williams et al. [7] stated
that patients who undergo the Jobe technique of reconstruction may be
predisposed to medial epicondylar fracture because three humeral bone tunnels
are required. The normal UCL graft can have a heterogeneous appearance on MRI.
In our experience, the UCL graft can appear even more heterogeneous but
remains intact and attached to the avulsed medial epicondyle. Medial
instability in these patients is purely a function of avulsion of the medial
epicondyle; once the fracture is reduced and fixed, medial stability is
restored.
Orthopedic surgeons and musculoskeletal radiologists should be aware of the
rare possibility of avulsion of the medial epicondyle after UCL reconstruction
in a throwing athlete who has medial elbow pain. This diagnosis should be
straightforward and should allow surgical planning to return the player to the
same level of competition.
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Abstract
Introduction
