Keywords
Orbital fractures - Enophthalmos - Orbital implants
INTRODUCTION
Orbital fractures are commonly seen with midfacial trauma. In the past, isolated blowout
fractures of the medial orbital wall were often overlooked because they are less symptomatic
than inferior orbital wall fractures. As computed tomography (CT) for facial trauma
patients has become popular, the reported incidence of medial orbital wall fractures
has increased in recent years.
Reconstruction of medial orbital wall fractures is a challenging problem for surgeons
because of the narrow operative field with complicated anatomical structures. In a
limited space, many structures conjoin to form the medial orbit. The medial orbital
wall is formed by the lamina papyracea of the ethmoid, lacrimal, sphenoid, and frontal
bones, along with the anterior and posterior ethmoidal arteries and the optic nerve.
The goal of treatment in patients with a medial orbital wall fracture is appropriate
reconstruction of the deformed orbital structure to restore the balance between the
volume of the orbital soft tissues and the orbital cavity.
The most well-known surgical technique, onlay implantation, involves the onlayed coverage
of bony defects with implant insertion onto the fracture site. The conjunctival approach
is very helpful for performing this procedure. The medial transcaruncular approach
leaves no detectable scars, leading to aesthetically pleasing results [1]. Many surgeon have performed this technique, but it is sometimes difficult for the
surgeon to maintain an optimal view. The limitation of this approach is that the operative
field is less visible, making it difficult to proceed with surgical procedures such
as dissection and the insertion of large alloplastic implants into this complex fractured
area [2]. This conventional onlay technique needs an area of subperiosteal dissection that
is wider than the measured fracture area. It requires that the displaced bone segments
be separated from the soft tissues [2]. To overcome those obstacles, the authors of the present study previously introduced
the inlay implanting method [2], which involves inserting alloplastic implants layer by layer into the ethmoidal
sinus of the fractured site. This inlay implanting technique needs minimal subperiosteal
dissection and can be used in comminuted medial orbital fractures, allowing adequate
reconstruction of orbital continuity without the fear of damaging the optic nerve.
However, both of onlay and inlay implantation require subperiosteal dissection, which
may lead to serious complications, such as bleeding or a nerve injury. Particularly
in patients with old fractures with posttraumatic enophthalmos, the scar tissue surrounding
the fracture site could be adhered with vessels, nerves, or extraocular muscles. Subperiosteal
dissection around the fracture site can therefore be dangerous. The adhesion is random
and unpredictable in a narrow operative field, making subperiosteal dissection more
difficult.
Bone repositioning without subperiosteal dissection can resolve this problem. This
method, in which the fractured bone segment is repositioned into the original position,
is considered ideal and physiologic in that it uses the fractured bone segment itself.
The bone repositioning method was introduced previously, using endoscopy or a balloon
catheter [3]
[4]. Recent advances in endoscopic techniques have allowed fractured medial orbital
walls to be repositioned with excellent visualization and complete dissection of the
circumference through the endoscopic transnasal approach. However, endoscopic equipment
is required, and the surgeon must be quite skillful at endoscopy.
In light of the above considerations, we sought to find a simple and minimally invasive
reconstruction method without subperiosteal dissection. Herein, we describe a modified
inlay implanting method including medial orbitotomy, referred to as the transcaruncular
“push-out” technique.
METHODS
Patients
Among the patients who were diagnosed with a unilateral medial orbital wall fracture
between August 2013 and December 2014, 16 underwent surgery for correction of a medial
orbital wall fracture. We began this study after all patients received information
on the purpose and possible side effects of examinations and signed an informed consent.
All authors have read the Declaration of Helsinki and have followed the guidelines
in this study. Among the 16 patients, 6 suffered from posttraumatic enophthalmos with
an old medial orbital wall fracture (the old fracture group), and 10 had an acute
medial orbital wall fracture (the acute fracture group). The indications for the operation
were as follows: reduced visual acuity, diplopia, abnormal extraocular muscle movement
(EOM), severe fracture (size of fracture greater than 2 cm2 on CT scans) or enophthalmos with a difference of more than 2 mm between the injured
and contralateral orbits.
Preoperative evaluation
Before the operation, all patients were evaluated for the position and symmetry of
the orbits, vision, diplopia, extent of EOM, any accompanying ocular diseases, or
any other symptoms. If necessary, patients were evaluated by an ophthalmologist who
understood the operation. The presence of enophthalmos was assessed with a Hertel
exophthalmometer (Oculus Inc., Wetzlar, Germany). Measurements were performed 3 times
by a single surgeon in each patient, and the mean of the 3 values was used. The orbital
volume was calculated using an Aquarius workstation (iNtuitionaquarius, ver. 4.4.6.,
TeraRecon, San Mateo, CA, USA). In order to plan a precise operation, we analyzed
the axial and coronal views of CT scans to assess the status of orbital structures,
such as the size of the bony defects and the degree of orbital tissue herniation.
We decided to use our push-out method when there was no soft tissue entrapment.
Surgical technique
The preoperative design was marked between the caruncle and plica semilunaris conjunctivae
for a transcaruncular incision. The marked area was incised, and through this incision,
minimal subperiosteal dissection proceeded up to the bony rim of the medial orbit.
Subsequently, a bony hole was created on the anterior wall of the medial orbital rim
using a drill. Then, medial orbitotomy was performed with an osteotome and mallet.
We inserted a thin periosteal elevator into the ethmoidal sinus via the medial orbitotomy
approach and detected the displaced bone segment. When reaching for the fractured
segment, we gently placed pressure on the periosteal elevator and gradually corrected
the fracture ([Fig. 1]). The process we have just described is referred to as the “push-out” technique.
We then inserted and placed porous polyethylene implants in small pieces into the
ethmoidal sinus. Implants were placed under the fractured bone segment to counteract
the tendency for displacement to recur. To confirm ocular mobility, the forced duction
test with toothed forceps was repeatedly conducted. Finally, primary closure at the
incision was performed and postoperative dressing with an ointment was performed.
Fig. 1. Intraoperative photograph of the “push-out” technique
(A-C) Schematic drawing and intraoperative photograph of the “push-out” technique
for reconstruction of the medial orbital wall. (A) The blue arrow indicates the insertion
of a thin periosteal elevator into the ethmoidal sinus via the medial orbitotomy approach.
(B) The blue arrows indicate gentle and gradual correction of the fractured segment
by the periosteal elevator.
Postoperative evaluation
We had a median follow-up period of 9 months, ranging from 6 to 15 months. A Hertel
exophthalmometer (Oculus Inc.) was used to assess the extent of enophthalmos. A postreconstructive
functional assessment was performed as well, with an evaluation of diplopia and EOM
limitations. In order to assess the aesthetic outcomes, preoperative and postoperative
CT scans were reviewed. Postoperative orbital volumetric measurements were made with
an Aquarius workstation.
Statistical analysis
The Wilcoxon signed-rank test was used to analyze perioperative differences in the
orbital volumes measured using the Aquarius workstation and the Hertel scale between
the 2 orbits. P-values <0.05 were considered to indicate statistical significance.
All statistical analyses were performed using SPSS ver. 20.0 (IBM Corp., Armonk, NY,
USA).
RESULTS
All 16 medial orbital wall fracture patients in the current study were adequately
treated. Restoration of the normal orbital cavity shape was identified on the axial
and coronal views of postoperative CT scans in all cases. No complications occurred,
except for 1 patient in whom some of the comminuted fracture was missed on preoperative
imaging; this patient underwent a revisional operation because of newly developed
diplopia after the operation. The patient who underwent the revisional operation showed
improved diplopia symptoms. In patients with an old medial orbital wall fracture,
the median (interquartile range, IQR) orbital volume of the fractured side was 29.22
cm3 (28.31–29.98 cm3) preoperatively, which significantly improved to a postoperative value of 25.13 cm3 (24.41–25.80 cm3). In patients with an acute medial orbital wall fracture, the median (IQR) orbital
volume of the fractured side was 28.73 cm3 (27.86–29.49 cm3) preoperatively, which significantly improved to a postoperative value of 24.90 cm3 (24.33–25.66 cm3) ([Table 1]). In patients with an old medial orbital wall fracture, the median (IQR) difference
on the Hertel scale was 2.13 mm (2.06–2.22 mm) preoperatively, which improved to 0.25
mm (0.22–0.27 mm) postoperatively. In patients with an acute medial orbital wall fracture,
the difference on the Hertel scale was 1.67 mm (1.61–1.74 mm) preoperatively, improving
to 0.33 mm (0.31–0.36 mm) ([Table 2]).
Table 1.
Orbital volume changes measured using the Aquarius workstation
|
Orbital volume
|
Old fracture group (n = 6)
|
Acute fracture group (n = 10)
|
|
Non-fractured orbit (cm3)
|
Fractured orbit (cm3)
|
Non-fractured orbit (cm3)
|
Fractured orbit (cm3)
|
|
Values are presented as median (interquartile range).
a) Postoperative computed tomography scan was performed as soon as the patients left
the recovery room after operation.
|
|
Preoperative
|
24.33 (23.57–24.81)
|
29.22 (28.31–29.98)
|
24.97 (24.07–25.65)
|
28.73 (27.86–29.49)
|
|
Postoperativea)
|
24.33 (23.57–24.98)
|
25.13 (24.41–25.80)
|
24.97 (24.07–25.65)
|
24.90 (24.33–25.66)
|
|
P-value
|
-
|
0.021
|
-
|
0.019
|
Table 2.
Changes on the Hertel scale measured by a Hertel exophthalmometer (Oculus Inc.)
|
Difference of Hertel exophthalmometer scale (mm)
|
Old fracture group (n = 6)
|
Acute fracture group (n = 10)
|
|
Values are presented as median (interquartile range).
a) Postoperative assessment of Hertel exothalmometer scale was performed when the
patient arrived at ward after the operation.
|
|
Preoperative
|
2.13 (2.06–2.22)
|
1.67 (1.61–1.74)
|
|
Postoperativea)
|
0.25 (0.22–0.27)
|
0.33 (0.31–0.36)
|
|
P-value
|
0.010
|
0.018
|
Case descriptions
Case 1
A 38-year-old woman visited the outpatient clinic with enophthalmos on the left side.
She had been in a car accident 1 year ago. At the time of the visit, she did not show
any functional problems related to diplopia, impaired vision, or abnormal ocular movements.
The medial orbital wall fracture and herniated orbital contents on the left side were
identified on a CT scan. She underwent an operation using the push-out technique.
The herniated orbital contents and the fractured bone segment were restored to the
original anatomical position. Three porous polyethylene implants measuring approximately
15 mm×6 mm, with a thickness of 3 mm, were placed in the ethmoidal sinus layer by
layer. Postoperative CT imaging revealed an adequately reconstructed medial orbital
wall ([Fig. 2]). No complications were observed.
Fig. 2. Old fracture case
Computed tomography (CT) scans of the the orbit obtained before and after the operation.
The orbital volume of the fractured side was 28.11 cm3 preoperatively and improved postoperatively to 24.89 cm3. The difference on the Hertel scale was 2.02 mm preoperatively, and improved to 0.20
mm postoperatively. (A) Preoperative and postoperative axial CT scans demonstrating
that the herniated orbital contents were restored completely. (B) Preoperative and
postoperative coronal CT scans demonstrating that the herniated orbital contents were
restored completely. (C) Preoperative and postoperative photographs of the patient
Case 2
A 12-year-old male patient visited the emergency room with midfacial trauma resulting
from a bicycle accident. The midfacial trauma resulted in a pure medial wall fracture
with no other concomitant midfacial fractures. At the time of the visit, he had no
functional problems related to diplopia, impaired vision, or abnormal ocular movements.
The medial orbital wall fracture and herniated orbital contents on the left side were
identified on a CT scan. He underwent an operation using the push-out technique. The
herniated orbital contents and the fractured bone segment were restored to the original
anatomical position. Porous polyethylene implants were placed in the ethmoidal sinus
layer by layer. Postoperative CT imaging revealed an adequately reconstructed medial
orbital wall ([Fig. 3]). No complications were observed.
Fig. 3. Acute fracture case
Computed tomography (CT) scans of the orbit obtained before and after the operation.
The orbital volume of the fractured side was 28.65 cm3 preoperatively, and improved to 25.10 cm3 postoperatively. The difference on the Hertel scale was 1.65 mm preoperatively,
and improved to 0.30 mm postoperatively. (A) Preoperative and postoperative axial
CT scans demonstrating that the herniated orbital contents were restored completely.
(B) Preoperative and postoperative coronal CT scans demonstrating that the herniated
orbital contents were restored completely.
DISCUSSION
The symptoms of medial orbital wall fractures are usually less severe than those of
inferior wall fractures because less muscle incarceration takes place and the bony
structure is multiply overlapped [5]. Since medial orbital wall fractures are often asymptomatic, they have received
less attention in the literature [6]
[7]. However, they may cause complications such as diplopia, enophthalmos, and the entrapment
of extraocular muscles [8]
[9]. In particular, enophthalmos may not appear immediately after the trauma because
soft tissue swelling can last weeks or months. The key to preventing such complications
is not only to make an accurate diagnosis, but also to reconstruct the fractured wall
of patients in whom surgery is indicated. CT scans enable more accurate diagnoses
of orbital fractures, especially the medial wall type [8]
[10]. Surgical correction is generally necessary in patients with the following symptoms
and signs: diplopia lasting over a week, limited EOM, blurred vision resulting from
optic nerve compression, a bone deficit greater than 2 cm, or enophthalmos resulting
from orbital tissue herniation [11].
The medial orbital wall is formed by the lamina papyracea of the ethmoid, lacrimal,
sphenoid, and frontal bones, along with the anterior and posterior ethmoidal arteries,
the optic nerve, and other structures. The anatomical complexity of the periorbital
area is challenging for surgeons and has spurred a constant search for less invasive
methods. To improve surgical outcomes and to reduce complications, various techniques
for reconstructing the medial orbital wall have been introduced. The inlay implanting
technique, in which multiple porous polyethylene implants are inserted into the ethmoid
sinus, has been reported to lead to successful outcomes with few complications. However,
when confirming the defect margin of medial orbital wall fractures and detaching the
bone and soft tissue around the pathologic area, complications remain possible, as
when the conventional method is used. In cases of post-traumatic enophthalmos caused
by a medial orbital wall fracture, adhesion of the bone, periosteum, and soft tissue
makes the dissection of the fractured bone segment difficult.
The purpose of this study was to develop a minimally invasive and simple surgical
method with a reduced range of dissection. Without dissecting and removing the fractured
bone segments by excessive force, herniated orbital tissue alongside the fractured
bone can be repositioned just by “pushing out.” We were able to reduce the operating
time and did not have to worry about complications caused by dissection around the
fracture site, such as bleeding, nerve injuries, and soft tissue injuries.
Only one patient underwent a revisional operation immediately after the operation
because of newly developed diplopia. He had a comminuted fracture, and a tiny fractured
segment was located toward the medial orbital wall, with an orientation that was almost
vertical. We missed it on preoperative CT scans. During repositioning of the fractured
bony wall, the medial rectus muscle was pricked by the fractured segment. We found
the problem on immediate postoperative CT scans, and removed the segment in a revisional
operation. The patient who underwent the revisional operation showed improved diplopia
symptoms.
In cases of the late correction of old medial orbital wall fractures with post-traumatic
enophthalmos, the push-out technique is useful because the mucous membrane surrounding
the fractured orbital wall is intact, making the reduction of a single segment more
feasible. By using the push-out technique, a surgeon can avoid unnecessary subperiosteal
dissection, which may be dangerous due to extensive scar tissue and bleeding from
fibrovascular sources. The push-out technique is also indicated for greenstick fractures
in young, soft bone in which the ethmoid bone bends and breaks. The bone segments
involved with a greenstick fracture are commonly larger and have a low risk of being
broken during the push-out technique. The push-out technique is useful for single-hinged
trapdoor-type fractures when soft tissue is not entrapped.
PATIENT CONSENT
The patient provided written informed consent for the publication and the use of their
images.
