Download Intra-articular Saucerization of the Acetabular Cotyloid Fossa

■ Case Report
Hip Arthroscopy: Intra-articular Saucerization
of the Acetabular Cotyloid Fossa
JAMES K. BRANNON, MD, FAAOS
abstract
Full article available online at ORTHOSuperSite.com. Search: 20120123-23
Hip arthroscopy is increasingly recognized as a treatment option for patients with hip
pain and labral tears. When emphasis is placed on labral tears as a primary clinical
finding in the peripheral compartment, a broader view of the pathophysiology of these
tears may be missed. Therefore, it is imperative to gain arthroscopic surgical access to
the central compartment and determine if its contents affect the congruency of the hip
joint. Abnormal bone and fibro-fatty tissue in the cotyloid fossa decrease the space
available for the ligamentum teres, leading to lateral subluxation of the femoral head
and rim loading of the acetabulum at the chondrolabral junction. Rim loading of the
acetabulum may induce articular-sided labral tears due to hip incongruency. Although
these labral tears may require refixation, the congruency of the hip joint should be
restored to the best extent possible. Arthroscopic intra-articular saucerization and debridement of space-occupying lesions in the cotyloid fossa increase the space available for the ligamentum teres, improve the congruency of the hip joint, and mitigate
against acetabular rim loading. This article describes a case of arthroscopic intra-articular saucerization of the cotyloid fossa in a 25-year-old man with chronic hip pain.
Figure: Arthroscopic image showing a tear in the
ligamentum teres as it enters the femoral head at
the fovea (arrow).
Dr Brannon is from Orthopedic Sciences, Inc, Seal Beach, California.
Dr Brannon patented the hip scope used in this case and has 90% stock ownership of Orthopedic
Sciences, Inc.
Correspondence should be addressed to: James K. Brannon, MD, FAAOS, Orthopedic Sciences, Inc,
3020 Old Ranch Pkwy, Ste 325, Seal Beach, CA 90740 ([email protected]).
doi: 10.3928/01477447-20120123-23
e262
ORTHOPEDICS | ORTHOSuperSite.com
INTRA-ARTICULAR SAUCERIZATION OF THE ACETABULAR COTYLOID FOSSA | BRANNON
T
he space available for the ligamentum teres in the cotyloid fossa allows the femoral head to remain
congruent in the acetabulum as the ligamentum teres becomes taut or lax during
external and internal rotation of the hip,
respectively. Congruency of the hip joint
may be compromised if the available
space for the ligamentum teres is insufficient. This article describes a case of
arthroscopic decompression of the cotyloid fossa to improve the space available
for the ligamentum teres to promote congruency of the hip joint and to mitigate
against articular-sided labral tears.
CASE REPORT
A 25-year-old man presented with a
3-year history of right hip pain that he described as a deep ache and rated as a 10/10
on the visual analog scale. He reported no
mechanical symptoms or instability while
walking. The patient located the pain deep
posteriorly in the hip joint and in the sciatic nerve region. The pain frequently
woke him at night, and he was unable to
sleep comfortably, particularly when lying on the affected side. On occasion, the
pain prevented him from ascending stairs
and sitting for ⬎30 minutes. He reported
no history of trauma or prior hip treatment,
and he did not participate in sports.
Physical examination demonstrated
normal external rotation and extension,
and the straight-leg raise test was negative.
However, the patient had moderate to severe
pain localized to the hip joint during internal
rotation, with the hip in 0° of flexion while
in a supine position. This pain was substantially exacerbated with direct axial impact
loading of the foot while the hip remained
internally rotated with 0° of flexion (cotyloid test). Flexion, adduction, and internal
rotation, the test for femoroacetabular impingement was negative. Flexion, abduction, and external rotation (FABER maneuver) relieved his symptoms.
The patient’s history and physical examination were not suggestive of infection,
and plain radiographs revealed coxa valga
FEBRUARY 2012 | Volume 35 • Number 2
1A
1B
Figure 1: Preoperative anteroposterior radiograph showing a valgus neck. Mild osteopenia (dashed arrow).
Acetabular sourcil (short arrow) (A). Preoperative lateral radiograph showing bony confluens between a
thickened medial wall and the medial margin of the acetabular sourcil, which represents the heterotopic
bony in the cotyloid fossa compromising the space available for the ligamentum teres (solid arrow). Mild
osteopenia (dashed arrows). Acetabular sourcil (short arrow) (B).
2B
2A
Figure 2: Coronal T1-weighted magnetic resonance image showing bony confluens between the medial margin
of the acetabular sourcil and heterotopic bone in the cotyloid fossa (dashed arrow). Medial wall (dashed arrow)
(A). Axial T1-weighted magnetic resonance image showing the medial wall (dashed arrow). The heterotopic
bone (solid arrow) occupying the cotyloid fossa is in contact with the ligamentum teres (short arrow) (B).
with a thickened medial wall that appeared
to be contiguous with the acetabular sourcil.
At the superior margin of the cotyloid fossa
on the anteroposterior view, mild osteopenia
was observed, which suggested the presence
of bone bruising due to abnormal weight
bearing at the apex of the cotyloid fossa.
A possible crossover sign was observed
but considered insignificant in the absence
of intraoperative labral findings (Figure 1).
Magnetic resonance imaging (MRI) without
contrast did not reveal a labral tear; howev-
er, heterotopic bone occupying the cotyloid
fossa was in contact with the ligamentum
teres, inducing a lateral translation force on
the femoral head and causing rim loading
of the acetabulum, which causes articularsided labral tears at the chondral labral junction. If a labral tear is identified, disease
within the central compartment should be
evaluated (Figure 2). We did not offer the
patient a diagnostic injection.
Due to the mechanical consequences of
the heterotopic bone in the cotyloid fossa,
e263
■ Case Report
the patient underwent hip arthroscopy. The
suction-seal typically provided by the labrum
was not present during primary distraction of
the hip joint. We used a 7.0-mm clear cannula and established the anterolateral portal.
A 3.0-mm 30° scope with a 5-mm sheath
was passed through the clear cannula into
the hip joint. Through this portal, in-flow
and out-flow was achieved. Through the
anterolateral portal, we identified a hypertrophic ligamentum teres, heterotopic bone,
and fibro-fatty tissue in the cotyloid fossa
(Figure 3). Lesions in the cotyloid fossa
impede a more normal medial position of
the ligamentum teres and impart a lateral
force on the femoral head during rotation
of the acetabulum.
A visual perspective of the joint was obtained, extending from the cotyloid fossa
in the central compartment to the labrum
in the peripheral compartment (Figure 4).
This maneuver allowed us to determine the
presence of an articular-sided labral tear in
relation to the heterotopic bone in the cotyloid fossa (ie, contrecoup lesion). We then
examined the area of the cotyloid fossa that
made contact with the femoral head. This
area was contiguous with the medial margin
of the articular surface of the acetabulum. In
view of the location of this heterotopic bone,
a posterolateral portal was established. An
anterior portal was not required. Through the
posterolateral portal, the cotyloid fossa was
saucerized (ie, decompressed and reshaped)
(Figure 5).
Saucerization of the cotyloid fossa relieved the abnormal area of contact with
the femoral head and increased the space
available for the ligamentum teres (Figure
6). The ligamentum teres demonstrated a
tear that was probably due to abnormal
contact with the superior apex of the floor
of the cotyloid fossa, which was debrided
as it entered the femoral head at the fovea (Figure 7). To successfully decompress and reshape the cotyloid fossa, we
confirmed that the tips of our scope and
shaver created a triangular apex deep in
the central compartment, not the peripheral compartment as is normally achieved
e264
4
3
Figure 3: Arthroscopic image showing fibrous tissue overlying the heterotopic bone within the cotyloid fossa (dashed arrow) and hypertrophic ligamentum teres (solid arrow).
Figure 4: Arthroscopic image showing an intact labrum (arrow), observed through the clear cannula,
directly lateral to the lesion in the cotyloid fossa. The
labrum and acetabular rim were intact.
5B
5A
Figure 5: Arthroscopic image showing the Nitinol wire touching the heterotopic bone (solid arrow). The
Nitinol wire was inserted through the posterolateral portal. Fluoroscopy was obtained simultaneously
and showed that this area was confluent with the medial margin of the acetabular sourcil (A). Complete
saucerization of the cotyloid fossa where the ligamentum teres will rest (solid arrow). The medial margin
of the acetabular sourcil (short arrow) (B).
6
Figure 6: Arthroscopic image showing the floor
of the cotyloid fossa with a thickened medial wall
(dashed arrow) where the residual pulvinar and
inferior extent of the ligamentum teres will rest.
Area of the cotyloid fossa that has been saucerized
where the superior apex of the floor of the cotyloid
fossa was separated from the medial margin of the
acetabular sourcil, improving the space available
for the ligamentum teres (solid arrow).
7
Figure 7: Arthroscopic image showing a tear in the
ligamentum teres as it enters the femoral head at
the fovea (arrow).
ORTHOPEDICS | ORTHOSuperSite.com
INTRA-ARTICULAR SAUCERIZATION OF THE ACETABULAR COTYLOID FOSSA | BRANNON
8A
8B
8C
Figure 8: Anteroposterior (A) and lateral (B) radiographs showing the normal relationship at the superior
apex of the cotyloid fossa between the medial margin of the acetabular sourcil with the medial wall (solid
arrows). A step-off is well observed. Acetabular sourcil (solid arrow). Sufficient space for the ligamentum
teres in the cotyloid fossa (dashed arrow) (C).
9B
9A
Figure 9: Postoperative anteroposterior radiograph showing the medial margin acetabular sourcil (solid
arrow) separated from the floor of the cotyloid fossa (dashed arrow) (A). Postoperative frog-lateral radiograph showing the medial margin of the acetabular sourcil (solid arrow). Sufficient space is available for
the hypertrophic ligamentum teres (B).
during labral repairs. Placement of the
second arthroscopic portal was based
on the location of the visible disease observed through the single anterolateral
portal. The hip joint was reduced and extensively ranged under direct arthroscopic
visualization.
A small cystic adenomatoid malformation (CAM) lesion was also found intraoperatively on the anterolateral femoral
neck that appeared to impinge against the
superolateral rim of the acetabulum during flexion. Arthroscopic removal of the
CAM lesion was performed through the
posterolateral portal using an arthroscopic
FEBRUARY 2012 | Volume 35 • Number 2
burr. A beaver blade was not used to perform an arthrotomy of the hip joint to
avoid compromising the stability of the
hip joint provided by the joint capsule.
At 6-week follow-up, the patient was fully ambulatory and demonstrated full range
of motion, with the complete absence of hip
pain during activities of daily living.
DISCUSSION
The indications for hip arthroscopy
continue to expand. When an articularsided labral tear is identified, its refixation
after acetabular rim trimming is often performed. However, it is important to deter-
mine if pain in these hips is also due to
disease in the central compartment. This
concern may be more ominous when heterotopic bone in the cotyloid fossa causes
abnormal weight bearing against the medial wall.
Our case demonstrated evidence of mild
acetabular dysplasia, where a periacetabular osteotomy may have been considered as
a treatment option.1 Although a thickened
medial wall may be a common finding in
acetabular dysplasia, developmental dysplasia of the hip (Legg-Calve-Perthes), the
heterotopic bone seen on MRI in the cotyloid fossa, was a significant finding because
this bone was contiguous with the medial
margin of the acetabular sourcil. Figure 8
shows the normal relationship between the
acetabular sourcil and the cotyloid fossa.
Hip arthroscopy and intra-articular saucerization of the cotyloid fossa (reshaping
and decompression of the cotyloid fossa)
was selected for this patient to eliminate
abnormal weight bearing of the medial wall
and increase the space available for the ligamentum teres. The absence of preoperative
femoroacetabular impingement symptoms
and a labral tear allowed us to focus on the
findings in the central compartment as a
source of pain and to further contemplate
these findings potentially being present in
the nondysplastic hip with a labral tear.2
A positive cotyloid test does not exclude the presence of a labral tear; however, arthroscopic access to the central
compartment provided a specific instrument trajectory that positioned potential
peripheral compartment disease in the operative field of the arthroscopic triangle.
It is important to understand the normal
anatomic relationship of the acetabular
sourcil to the medial wall. Abnormal findings must be correlated with the preoperative physical examination.
Our patient’s preoperative physical examination did not correlate with the small
CAM lesion observed on MRI; however,
clear impingement was present on arthroscopy, suggesting that in the absence
of repetitive trauma to the labrum that may
e265
■ Case Report
be observed in the young athlete, labral pathology and CAM and pincer lesions in
nonathletes may be induced by or associated with disease in the central compartment. Consequently, CAM lesions may
not contribute to preoperative pain, or may
do so to varying degrees. Regardless, clinical findings attributable to CAM lesions
should not exclude the diagnostic evaluation of the central compartment. When
more advanced disease exists in the central
compartment, patients may report instability and grinding sensations during ambulation, particularly if the ligamentum teres is
torn. Figure 9 shows postoperative radiographs at 6-week follow-up.
Removal of the heterotopic bone in
the cotyloid fossa eliminated the source
of hip pain and a potential translation
force imparted on the femoral head during gait. This translation force may in-
e266
duce lateral subluxation of the femoral
head and is most likely to occur during
midstance through toe-off (ie, internal rotation and axial loading of the hip
joint). Furthermore, in the presence of a
contained hip, lateral subluxation of the
femoral head could cause articular-sided
labral tears and blistering of the adjacent
acetabular cartilage due to rim loading of
the acetabulum.
Arthroscopic intra-articular saucerization of the cotyloid fossa defines the true
medial margin of the acetabulum and its
floor. When combined with acetabular rim
trimming, normal weight bearing of the
acetabular articular cartilage is facilitated
postoperatively. Although it is important
to address peripheral compartment disease during hip arthroscopy, it is imperative to reshape and decompress the cotyloid fossa in areas of abnormal femoral
head contact. Computed tomography may
be useful in defining the extent of heterotopic bone. However, if the operative clinical criteria have been met, a single, wellplaced anterolateral portal, alternating
between a 30° and 70° scope, will allow a
complete diagnostic evaluation of the central compartment. Preoperative radiographs and MRI should be used to fully
characterize the relationship of the sourcil
to the cotyloid fossa to improve surgical
planning.
REFERENCES
1. Kain MSH, Novals EN, Vallim C, Millis MB,
Kim Y-J. Periacetabular osteotomy after failed
hip arthroscopy for labral tears in patients with
acetabular dysplasia. J Bone Joint Surg Am.
2011; 93(suppl 2):57-61.
2. Wenger DE, Kendell KR, Miner MR, Trousdale RT. Acetabular labral tears rarely occur
in the absence of bony abnormalities. Clin
Orthop Relat Res. 2004; (426):145-150.
ORTHOPEDICS | ORTHOSuperSite.com