FOOT & ANKLE INTERNATIONAL
Copyright  2004 by the American Orthopaedic Foot & Ankle Society, Inc.
Arthroscopic Treatment for Anterior Impingement Exostosis of the Ankle:
Application of Three-Dimensional Computed Tomography
Masato Takao, M.D., Ph.D.∗ ; Yuji Uchio, M.D., Ph.D.∗ ; Kohei Naito, M.D., Ph.D.∗ ; Taisuke Kono, M.D.; Kazunori Oae, M.D.;
Mitsuo Ochi, M.D, Ph.D.†
Shimane, Japan; Hiroshima, Japan
pain and limit dorsiflexion of the ankle during activity.
The symptoms caused by osteophytes are variously
called athlete’s ankle,8 footballer’s ankle,7 anterior
ankle impingement,2,11,12,14,18 anterior tibiotalar spur,15
anterior ankle osteophytes,3 or anterior impingement
exostosis (AIE).10,13,16 . We use the latter term throughout
this article.
When treating AIE, it is difficult to gain excellent
results consistently with every patient, especially if
they have stage III lesions2 according to Scranton’s
radiological classification.15 One of the reasons for this
difficulty is that the location and number of osteophytes
cannot be conclusively determined preoperatively using
standard radiography. Three-dimensional computed
tomography (3DCT), however, has proved to be an
excellent tool to investigate the morphology and location
of these osteophytes.1,5,6 We used 3DCT to clarify the
location, shape, and size of AIEs preoperatively, and we
performed arthroscopic resection of the osteophytes.
The purpose of this study was to evaluate the operative
results of excision of AIE using 3DCT to assist
preoperatively.
ABSTRACT
The purpose of this study was to evaluate the operative
results of excision of anterior impingement exostoses
of the ankle. Preoperative three-dimensional computed
tomography (3DCT) was used to make the diagnoses.
The authors evaluated 16 ankles of 16 patients who
underwent arthroscopic resection of the osteophytes
of their anterior distal tibia or dorsal talus. They were
followed up for 24–51 months. All 16 patients had 3DCT
preoperatively, which allowed the authors to determine
the exact location, shape, size, and number of the
osteophytes. All of the osteophytes were resected using
arthroscopic techniques. At the time of the most recent
follow-up, the mean AOFAS score was 80.5 ± 4.9 points
at preoperation, and 97.0 ± 3.7 points at the most recent
follow-up. There were significant differences between the
pre- and postoperative AOFAS scores and those of the
most recent follow-up period for each group (p < .0001).
It is necessary to clarify the location, size, shape, and
number of all of the osteophytes preoperatively using
3DCT, and to then resect them all.
Key Words: Ankle; Arthroscopy; Impingement; Osteophytes
MATERIALS AND METHODS
INTRODUCTION
We evaluated 16 ankles of 16 patients who underwent
arthroscopic resection of osteophytes of their anterior
distal tibia or dorsal talus between April 1997 and July
1999. There were nine males and seven females in
the study, and their age at the time of surgery ranged
from 17 to 52 years (mean, 37.1 ± 11.0 years). They
were followed up for 24 – 51 months (mean, 31.8 ± 6.9
months) (Table 1). Plain lateral radiographs of all 16
ankles were examined and were classified according
to Scranton’s classification15 : stage I —osteophyte less
than 3 mm; stage II — osteophyte greater than 3 mm;
stage III —anterior tibial osteophyte with secondary talar
osteophyte (kissing lesion); stage IV—panarthritis. The
study included one case of stage I, nine cases of stage II,
In general, most osteophytes do not cause symptoms
or dysfunction. In some people they cause anterior ankle
∗
Department of Orthopaedic Surgery, Shimane University School of Medicine,
Shimane, Japan
†
Department of Orthopaedic Surgery, Hiroshima University School of Medicine,
Hiroshima, Japan
Corresponding Author:
Masato Takao, M.D., Ph.D.
Assistant Professor
Department of Orthopaedic Surgery
Shimane University School of Medicine
89-1, Enya, Izumo
Shimane 693-8501, Japan
E-Mail: [email protected]
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TAKAO ET AL.
Foot & Ankle International/Vol. 25, No. 2/February 2004
Table 1: Data on the 16 patients who had an
anterior impingement exostosis of the ankle
Case
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Gender
Scranton
Duration of
Age at Op. Classification Follow-up
(yrs)
(mos)
M, 23
M, 43
F, 26
F, 33
M, 52
M, 35
M, 28
F, 51
M, 17
M, 44
F, 26
F, 46
M, 31
F, 45
F, 46
M, 47
I
II
II
II
II
II
II
II
II
II
III
III
III
III
III
III
51
27
28
28
33
34
34
35
38
38
24
24
26
26
31
32
six cases of stage III, and no cases of stage IV (Table 1).
There were no combined disorders.
All 16 patients had 3DCT preoperatively to investigate
the location, shape, size, and number of osteophytes
(Fig. 1A). Based on the 3DCT, we outlined the assumed
anatomical location of all the AIE lesions (Fig. 1B).
We then resected the lesions arthroscopically, using
a motorized shaver according to the 3DCT scan.
Ankle arthroscopy was performed with the patient
under spinal lumbar anesthesia. The patient was placed
in a supine position. The hip was flexed 45◦ in
a leg holder by means of the bandage distraction
technique using a force of 78.4 N.17 The arthroscope
and the motorized steel bar were inserted at the
anterolateral and anteromedial portals so that the dorsal
talus and anterior distal tibia could be observed. The
motorized steel bar with suction was used to resect the
osteophytes on the anterior distal tibia and/or dorsal
talus (Fig. 2). When resecting an osteophyte, the guard
of the steel bar was toward the capsule to protect the
neurovascular structures. Also, the ankle joint was be
kept at a slightly dorsiflexed position to open up the
anterior compartment.18 After resection of all of the
osteophytes as determined preoperatively by 3DCT,
the ankle was dressed with an elastic bandage without
immobilization.
Active range-of-motion exercises of the ankle were
performed beginning 1 day after surgery. Two weeks
after the operation, passive range-of-motion exercises
were added to the patients’ exercise routine. Partial
weightbearing was allowed beginning 2 weeks after
surgery, and full weightbearing after 4 weeks. Physiotherapy, which was supervised by a physical therapist,
was performed every day for 2 weeks and then twice a
day for the next 2 weeks. It included range-of-motion
exercises of the ankle, and strengthening of the anterior tibial muscle, the peroneal muscles, and the calf
muscles. The patients were allowed to resume their
athletic activities 2 months after the operation.
For our control group, we performed arthroscopic
osteophyte resection in AIE patients without preoperative
Fig. 1: A, Preoperative 3DCT of right ankle. Arrowheads show the osteophytes on the distal tibia and the dorsal talus. B, Preoperative 3DCT of
right ankle. Traced areas show the lesions which should be resected.
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Foot & Ankle International/Vol. 25, No. 2/February 2004
ANTERIOR IMPINGEMENT EXOSTOSIS OF ANKLE
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The patients scored 88 points at preoperation and 100
points at the most recent follow-up in stage I; 82.4 ± 4.4
points (75 – 87 points) at preoperation and 96.8 ± 4.1
points (range, 90 – 100 points) at the most recent
follow-up in stage II; and 76.3 ± 1.5 points (75 – 78
points) at preoperation and 96.8 ± 3.7 points (range,
90 – 100 points) at the most recent follow-up in stage
III (Table 2). There were significant differences between
the AOFAS scores at preoperation, and that of the most
recent follow-up period for each group (p < .0001).
In the control group, the mean AOFAS score was
78.4 ± 4.8 points (range, 72 – 84 points) at preoperation
and 93.4 ± 6.1 points (range, 87 – 100 points) at the most
recent follow-up. There were significant differences
between the AOFAS score at the most recent followup of the experimental group and that of the control
group (p = .0053). Postoperative CT scan showed no
recurrent cases (Fig. 3).
Fig. 2: Operative photo showing resection of osteophyte on the distal
tibia using motorized steel bar.
3DCT on five feet of five patients. There were four
males and one female, whose ages at time of surgery
ranged from 26 to 44 years (mean, 35.2 ± 8.3). They were
followed up for 18 – 28 months (mean, 24.2 ± 3.9), and
included three cases in stage II and two in stage III of
Scranton’s classification.
At follow-up, all of the patients including the control
group received the Ankle-Hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS
score)4 and 3DCT. The pre- and postoperative AOFAS
and follow-up scores were compared by means of the
Student t test. The differences between the two groups
were considered to be statistically significant when p
was less than or equal to .05.
RESULTS
The mean AOFAS score was 80.5 ± 4.9 points (range,
75 – 88 points) at preoperation and 97.0 ± 3.7 points
(range, 90 – 100 points) at the most recent follow-up.
Fig. 3: Postoperative 3DCT of right ankle.
Table 2: Outcomes using AOFAS score
Scranton
Classification
Stage I
Stage II
Stage III
Total
AOFAS Score (Mean ± SD)
Patients (16 cases)
Control (5 cases)
Preop
Postop
Preop
Postop
88
82.4 ± 4.4
76.3 ± 1.5
80.5 ± 4.9
100
96.8 ± 4.1
96.8 ± 3.7
97.0 ± 3.7
—
76.7 ± 5.0
81.0 ± 4.2
78.4 ± 4.8
—
96.7 ± 5.8
88.5 ± 2.1
93.4 ± 6.1
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Foot & Ankle International/Vol. 25, No. 2/February 2004
DISCUSSION
Anterior ankle pain and/or limitation of dorsiflexion of
the ankle joint due to the presence of osteophytes on
the anterior tibia and/or dorsal talus was first described
by Morris8 as athlete’s ankle. In the present study, we
used the term anterior impingement exostosis. There
have been several opinions on the cause and origin
of AIE. Nicholas9 reported that osteophytes are the
outcome of an avulsion fracture of the anterior border
of the tibia and the neck of the talus. Parkes et al.12
reported that the chief cause is repeated stretching of
the joint capsule brought about by forced plantarflexion
and hence the deposition of calcium salts along its fiber.
Other authors15 reported that forced dorsiflexion results
in repeated microtraumas on the tibia and talus, leading
to microfractures of the trabecular bone or periosteal
hemorrhage, which then heal with the formation of new
bone. Van Dijk et al.18 reported that in cases where
extensive cartilage damage is already present because
of supination or direct trauma, repetitive kicking of a ball
can explain the development of the AIE. However, the
cause and origin of AIE remains largely unknown.
Scranton and McDermott15 categorized AIEs according to their size and location using standard radiographs.
Branca et al.2 clarified the results of arthroscopic
treatment of AIE according to Scranton’s classification,
and found the best results are obtained in stage I and
II. In stage III and IV, where the damage was extensive,
there were recurrences of the osteophytes, probably
resulting from insufficient removal of the tibial and
talar osteophytes and from degeneration. To improve
results in treating stage III or IV AIEs, it is necessary
to pinpoint the location and number of osteophytes
present, and to resect these osteophytes completely.
We believe that one of the reasons poor results are
obtained in treating stage III or IV AIEs is that it is
difficult to diagnose the location and number of the
osteophytes preoperatively using standard radiography
and, therefore, it is difficult to resect the osteophytes
completely. 3DCT is an excellent tool for investigating
the morphology and location of these osteophytes,1,5,6
because it makes it possible for the diagnostician
to pinpoint the location, shape, size, and number of
the osteophytes preoperatively. This information allows
thorough removal of the osteophytes and can lead to an
excellent operative result. We believe that it is necessary
to clarify all osteophytes preoperatively using 3DCT and
to resect all osteophytes using arthroscopic technique
in order to obtain an excellent clinical result of AIE.
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