Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
2004
Minimally Invasive Orthopaedic Trauma Surgery
A Review of the Latest Techniques
Kenneth A. Egol, M.D.
T
raditional plate and screw constructs are placed under
direct fracture exposure with anatomic reduction
of fracture fragments. These techniques in the past
have often required extensive periosteal stripping of bony
comminution under direct visualization. The problems associated with this approach include the potential for delayed
and non-union secondary to fracture site devascularization.
In order to minimize these potential problems, orthopaedic
surgeons have moved away from direct exposure of comminuted non-articular fracture segments and toward minimally
invasive and bridge plating techniques for diaphyseal and
meta-diaphyseal fractures. Along with this new surgical
philosophy, a new series of implants has been developed in
order to achieve these goals.
Minimally invasive surgery is currently a buzzword in all
fields of surgery.1-12 However, it is actually a concept that
has been used in orthopaedics for a long time. In his book
in 1989, Mast highlighted the delicate balance between the
degree of bony stabilization and surgical trauma imparted to
the soft tissues.13 We have been using many types of limited
or minimally invasive and biologically friendly techniques
in orthopaedic surgery. These concepts have included use
of the bridge plate, closed intramedullary nailing, external
fixation, cannulated screws, and more recently percutaneous plating. The common denominator between all of these
types of biological fixation is preservation of the soft tissue
attachments to the comminuted fracture fragments. The tenants of fracture surgery still include an anatomic reduction of
the articular surfaces, application of stable internal fixation
devices, preservation of the blood supply, and early active
pain-free mobilization of the limb. Advancements of these
Kenneth A. Egol, M.D., is an Assistant Professor of Orthopaedic
Surgery in the NYU-Hospital for Joint Diseases Department of
Orthopaedic Surgery, New York, New York.
Correspondence: Kenneth A. Egol, M.D., Hospital for Joint Diseases, 301 E 17th Street, New York, New York 10003.
techniques and the development of newer implants that minimize vascular damage have contributed to the development
of biologic internal fixation. By using indirect reduction, by
using longer plates to improve the mechanical leverage, and
by applying fewer screws to avoid unnecessary damage to
the bone, fracture union rates have improved. In a diaphysis
we are concerned about length, rotation, and mechanical axis,
and in these regions we have used intramedullary nails to achieve
the aforementioned goals. In the epiphyseal or articular regions,
anatomic reduction is mandatory and here, commonly, plate and
screw fixation is used to ensure stability.
Experimental Basis
The experimental basis for minimally evasive surgery is
based on the work of Rhinelander, who showed that twothirds of the blood supply to the bone is via the nutrient artery
and one-third comes from the inflow of the periosteum.14,15
The newer plating methods championed by Farouk and
Krettek5,7,11,16 spare the blood supply by limiting dissection
of the periosteum. Cadaveric femurs underwent lateral
conventional plate osteosynthesis (CPO) through a standard
lateral approach on one side and minimally invasive plate osteosynthesis (MIPO) through two three-centimeter incisions
on the contralateral side. Injection studies were performed
bilaterally to identify the femoral perforating and nutrient
arteries. The authors found that the MIPO specimens showed
intact perforating and nutrient arteries, whereas the CPO
specimens had a variable incidence of vessel disruption. The
MIPO group demonstrated better periosteal perfusion in each
of the cadavers and improved medullary perfusion in 70° of
the MIPO specimens compared with the CPO specimens.7 In
addition, Perrin has introduced limited contact plates or point
contact PC fix plates to achieve these same goals.17 Minimal
additional surgical trauma and flexible fixation allow prompt
healing when the blood supply to bone is maintained. The
biomechanical aspects principally address the degree of
Bulletin • Hospital for Joint Diseases
instability that may be tolerated by fracture healing under
different biological conditions. The strain theory of fracture
healing offers an explanation for the maximum instability
that can be tolerated and the minimal degree required for
induction of callus formation. The biological aspects of
damage to the periosteal blood supply, cortical necrosis, and
temporary cortical porosity help to explain the importance of
avoiding extensive contact of the implant with bone.17
Indications
The indications for minimally invasive fracture surgery
include all fractures amenable to these techniques. Limited incision or biological plating is used for periarticular
fractures with a metaphyseal/diaphyseal extension or those
extraarticular fractures not amenable to intramedullary nailing. Furthermore, percutaneous plating is favored in situations where there has been a compromise in the soft tissue
envelope secondary to the initial insult of the trauma. For
example, compartment syndrome, contused skin, fracture
blisters, or poor circulation.
Intramedullary nails, already biologically friendly,
are now being placed through smaller skin incisions with
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Volume 62, Numbers 1 & 2
2004
specially designed insertion guides and reduction tools that
allow for less exposure. The majority of long bone fractures
and hip fractures treated with IM nails can be done in a
percutaneous manner.
Techniques
The techniques involved in minimally invasive surgery may
involve the use of standard plate and screw constructs. These
plates can be pre-bent on bone models prior to surgery and
then placed through small incisions sliding them down submuscularly, but extraperiosteally, followed by percutaneous
placement of screws through image intensification (Fig.
1). In addition, new remodeled plates are pre-contoured to
anatomically fit various regions of the extremities. Devices
such as the fracture table, femoral distractor, or external
fixator aid the surgeon in obtaining an indirect reduction and
generalized alignment with respect to the mechanical and
anatomic axes prior to placement of the implants.13 Finally,
good radiographic visualization is imperative to be able to
perform these procedures in an efficient and skilled manner.
Image intensification with views at 90° to one another is
mandatory. Percutaneous plating is achieved by obtaining
B
Figure 1 A 45-year-old male with a distal fourth tibia-fibula
fracture. A, Radiograph of injury; B, Pre-bent plate placed percutaneously reduces the fracture; C, Surgical incisions after all
screws have been placed.
Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
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2004
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Figure 2 A, PCCP hip fixation device. B, Intra-operative photograph demonstrating placement through minimal incisions.
an indirect reduction prior to placement of the plate. Several
small incisions are made outside the zone of injury. The plate is
pre-contoured and slid into its position, which is confirmed by
x-ray image intensification, and either clamped or K-wired in
place. Next, screws are placed through several small incisions
without disruption of deep periosteum (Fig. 1).
The LISS plate is a new generation of implant designed
to treat meta-diaphyseal fractures. It is a locking plate
designed to be an internal/external fixator by the screws
locking to the plate.18-21 Angular stability is increased, thus
enhancing anchorage into metaphyseal bone, which may
improve fixation strength in osteoporotic bone. Insertion and
placement of the implant is performed via small incisions
by submuscularly sliding the plate along the bone. Screw
placement is performed via an attached targeting jig. The
screws are self-drilling, self-tapping, locking screws, which
are placed in unicortical fashion.
Femur
In the hip region, the PCCP is a newly designed hip implant
that allows for percutaneous placement and minimal additional muscular trauma for inter-trochanteric hip fractures
(Fig. 2A).22,23 Again, the wire is placed under image intensification into a center-center position within the head. The
plate is slid in a submuscular position and clamped to the
bone through stab incisions and all the screws are placed to
target devices (Fig. 2B). Implants of older design work well
with a percutaneous technique. A dynamic condylar screw
A
B
C
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Figure 3 A 71-year-old female who sustained a supracondylar periprosthetic femur fracture. A, Fixation with a DCS screw and long side
plate placed submuscularly; B, Skin incisions; C, AP radiograph at 8-months follow up; D, Lateral radiograph at 8-months follow up.
Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
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B
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Figure 4 A 40-year-old male who sustained a Schatzker VI tibial plateau fracture. A, Skin incisions used for LISS plate and screws; B,
AP radiograph reveals healing of the fracture at 6 months; C, Lateral radiograph reveals healing at 6 months.
can be used for periprosthetic or distal femur fractures, in
which a small incision is made into the distal segment. The
lag screw is drilled and placed into the distal fragment. The
side plate is then slid submuscularly and attached distally
over a guide wire onto the lag screw and clamped through
stab incisions to the femoral shaft (Fig. 3). Results reported
in the literature with minimally evasive techniques about
the proximal femur are encouraging. Kinast compared two
groups of patients, both treated with a 95° condylar blade
plate.24 One used standard open plating techniques and the
other minimally evasive with no stripping and percutaneous
plate placement. The authors found a six week decrease in
the healing time. The nonunion rate decreased from 16.6%
to 0%. They had a lower infection rate and there was no
difference in functional results. In the distal femur, Krettek
reported on the use of minimally evasive osteosynthesis
with distal femur fractures using a percutaneously placed
retrograde plate.16 He reported on 16 patients with 18 distal
femur fractures, 5 were OTA 33-A’s and 13 with OTA 33-C’s.
The mean ISS score was 19. The average follow-up was 33
months. All patients healed by 3 months and only 1 patient
healed with a valgus malunion of greater than 10°.
the LISS to a double plating construct.26 These investigators
found that 22 of the 24 fractures healed at 3 months and 2
required supplemental bone grafting. There were no infections and the range of motion of the knee was 1° to 110°
degrees of flexion. Furthermore, the biomechanical aspect of
the study showed that the unilateral locked plate was a stable
construct when compared to the double plating construct,
which had historically been used to treat these injuries.
The distal tibia is in a subcutaneous region, which makes
plating and open surgery in this region more risky. Often
the fibula can be used to gain length and indirectly reduce
the tibia fracture. Once again pre-bent plates or contoured
plates can be slid along the anteromedial border of the tibia
with screws placed subcutaneously (Fig. 5). Articular splits
can be stabilized with cannulated screws (Fig. 5). Helfet and
associates reported on 20 patients who underwent percutaneous plating of the distal tibia.6 All patients healed at 11 weeks
and good functional results were seen in all. However, four
patients in the series healed in a malunion of greater than
10°. These patients all underwent treatment with tubular
plates. These investigators have recommended against using
one third tubular plates in this region.
Tibia
Minimally invasive techniques have been used in the proximal tibia as well. Once again, for tibial plateau fractures, the
high-energy Schatzker type V’s and VI’s, anatomic articular
reconstruction is mandatory. These techniques are beneficial
in cases in which the fractures are extraarticular, but too
proximal to nail. The concepts remain the same. A lateral
incision is made. The plate is slid below the anterior tibialis
muscle, bypassing areas of fracture and comminution, and
stabilized with screws proximal and distal to the fracture
(Fig. 4).20,25 Egol and colleagues reported on 24 Schatzker
type V’s and VI’s, all treated using the LISS plate and compared this with a laboratory experiment, which compared
Pelvis and Acetabulum
Gaining popularity, iliosacral screw fixation affords a
minimally invasive avenue for stabilization of some complex
pelvic ring injuries27-32 (Fig. 6). The technique is technically
demanding and requires good image intensification as well
as the ability to anatomically reduce the sacroiliac joint
or sacral fracture. This can be accomplished via traction,
Schanz pins, or indirect reduction of the back by anterior
symphyseal plating. One must understand the anatomy of
the pelvis as well as the contraindications to this technique,
which include the presence of a dysmorphic pelvis, physician
unfamiliarity, and the inability to visualize under fluoroscopy secondary to contrast material, obesity, or bowel gas.
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Bulletin • Hospital for Joint Diseases
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Volume 62, Numbers 1 & 2
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Figure 5 A 49-year-old male who sustained a distal tibia fracture with intra-articular extension. A, CT scan reveals intra-articular extension; B, AP radiograph; C, Plate slid through a small distal incision above the periosteum; D and E, Percutaneous clamp placement aids
in reduction of the fracture; F, Percutaneous screw placement; G, Final radiograph at 6 months demonstrating healing.
Anterior pelvic fixation can be performed via percutaneous
methods, retrograde pubic rami screws are currently being
placed to minimize the approaches needed for anterior pelvic ring fixation (Fig. 7). Once again, it requires physician
comfort and good image intensification.
Spine
Vertebral compression fractures are a source of pain and
morbidity in the elderly. Some of these patients are too frail
to undergo traditional fusion surgery for multilevel fractures.
The advent of vertebroplasty or kyphoplasty provides a minimally invasive technique for treatment of these fractures with
reduction and stabilization through minimal incisions under
fluoroscopy.10,33-35 The injection of polymethylmetacrylate
(PMMA) is often a final attempt at therapeutic treatment of
complications due to such fractures. Vertebroplasty involves
injection of cement under high pressure via one or both
pedicles, thus filling and stabilizing the vertebra without
reduction of the fracture. Extravertebral cement leakage is
a common complication; an intact posterior wall normally
Bulletin • Hospital for Joint Diseases
Volume 62, Numbers 1 & 2
2004
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Figure 6 Percutaneous placement of an iliosacral screw: A, outlet view; B, Inlet view.
Figure 7 A, Schematic representation of the placement of a retrograde pubic ramus screw. B, Surgical technique for placement of a
retrograde ramus screw.
prevents cement leakage into the epidural space. Kyphoplasty involves transpedicular inflation of balloon tamps,
thus creating a cavity which is then filled with PMMA under
low pressure. Restoration of vertebral height is possible and
the potential for extravertebral cement leakage lessened.
Summary
Computer assisted fluoroscopic surgery is at the forefront of the ability to continue and pursue minimally
invasive surgical options in orthopaedic surgery. Many
systems afford the surgeon three-dimensional views and
biplanar imaging for placement of orthopaedic implants
in difficult areas.
The current literature regarding these techniques is
limited. The indications are poorly defined. The common
thread of all techniques, however, is the preservation of
the soft tissue attachments and the biology of the fracture hematoma. Currently we are using first generation
implants. It appears that malalignment is the biggest
problem with any of these techniques and long-term
prospective studies will be required to evaluate whether
or not these theoretical advantages become clinically
viable and functional for patient care.
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