Abstract
Background: Locked-plate fracture-fixation techniques and designs
continue to evolve. Polyaxial locking plates that allow screw angulation and
end-point locking have become available; however, there are no clinical data
documenting their strength and efficacy, to our knowledge. The purpose of this
study was to evaluate the clinical performance of a variable-axis locking
plate in a multicenter series of periarticular fractures about the knee.
Methods: Between 2003 and 2005, fifty-four patients with a total of
fifty-six fractures were treated with a polyaxial locked-plate fixation system
(DePuy, Warsaw, Indiana). There were twenty male patients and thirty-four
female patients with a mean age of fifty-seven years. There were twenty-five
distal femoral fractures and thirty-one proximal tibial fractures. Twelve of
the fractures were open. Clinical and radiographic data, including changes in
alignment, hardware breakage, or other mechanical complications of the device,
were retrospectively reviewed. Function was assessed with use of the Knee
Society scores. One patient with a bilateral fracture died less than three
months postoperatively, and two patients were lost to follow-up prior to
union. Fifty-two fractures in fifty-one patients were followed to union or for
a minimum of six months; the mean duration of follow-up was nine months
(range, six to twenty-five months).
Results: Forty-nine (94%) of the fifty-two fractures united. There
were no mechanical complications. Most importantly, there was no evidence of
varus collapse as a result of polyaxial screw failure. There were three deep
infections and one aseptic nonunion. No plate fractured, and no screw cut
out.
Conclusions: The variable-axis locking plates performed well, with a
high rate of fracture union and no evidence of varus collapse due to failure
of the polyaxial screw fixation, in a series of complex fractures about the
knee. Complication rates were similar to those for historical controls treated
with fixed-trajectory locking plates. Polyaxial locking plates offer more
fixation versatility without an apparent increase in mechanical complications
or loss of reduction.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.
Over the last decade, locked-plate fixation has become popular for the
treatment of complex fractures of the distal part of the femur and the
proximal part of the
tibia1-14.
This technology, coupled with the biological advantages of percutaneous
insertion, has resulted in high union rates and generally good outcomes in
patients with fractures that historically have been difficult to
treat15. Locked
plates allow multiple points of fixed angle support, thereby increasing the
likelihood of excellent periarticular
fixation5,16.
One of the major shortcomings of first-generation locked plates is the
inability to angle the screw in the threaded
hole5. Although the
predetermined angle of the threaded hole is often adequate, obstacles to
periarticular fixation, such as lag screws, fracture planes, or the components
of a total knee arthroplasty, can be
encountered5,17,18.
These situations necessitate the use of a shorter locked screw or an unlocked
screw placed through the threaded hole, both of which are undesirable when
periarticular fixation needs to be
maximized5,19.
Variable-axis, or so-called polyaxial, screws have been used for fixation
constructs in spine surgery for many
years20. The
ability to angle a screw and then lock it at that chosen angle is an obvious
advantage when, for example, pedicle screws are being placed in a patient with
excessive lumbar lordosis. This technology relies on hoop stresses as the
screw head engages a corresponding bushing. The application of this
proprietary polyaxial technology has recently been extended to plates intended
for fixation of periarticular fractures. The theoretical advantage is the
ability to avoid obstacles to fixation that would not be avoidable with the
insertion of screws at a predetermined angle. However, we are not aware of any
clinical data documenting the strength and utility of these new devices.
A polyaxial screw has less resistance to bending forces than a fixed
locking screw by virtue of the additional interface that relies on friction
from hoop stresses rather than from threads. Therefore, there is trade-off
between versatility and strength. It is unknown, however, what construct
strength is required for successful treatment of complex fractures about the
knee without loss of reduction and alignment.
The purpose of this retrospective study of a series of periarticular
fractures about the knee treated with a polyaxial locking plate was to
document the mechanical performance of the device and to compare it with that
in historical controls treated with fixed-trajectory locking plates.
Between 2003 and 2005, fifty-four patients with a total of fifty-six
fractures of the distal part of the femur or the proximal part of the tibia
were treated with the POLYAX plate (DePuy, Warsaw, Indiana). The patients were
treated at five level-I trauma centers by one of five traumatologists
experienced in locking-plate techniques. Institutional review board approval
for a multicenter retrospective review was obtained. Indications for fixation
with a polyaxial locking plate included a fracture that required coronal plane
stability and/or support of articular fragments in osteoporotic bone. There
were twenty male patients and thirty-four female patients with a mean age of
fifty-seven years (range, fifteen to ninety-nine years). There were
twenty-five distal femoral fractures (four OTA type 33A1, one type 33A2, ten
type 33A3, eight type 33C2, and two type 33C3) and thirty-one proximal tibial
fractures (five OTA type 41A3, seven type 41B3, and nineteen type
41C3)21. Forty-four
fractures were closed and twelve (21%) were open. Ten were periprosthetic
fractures. Two patients were lost to follow-up prior to fracture union, and
one patient with a bilateral distal femoral fracture died prior to the
three-month follow-up point. Therefore, fifty-two fractures in fifty-one
patients were followed until fracture union or for a minimum of six months;
the mean duration of clinical follow-up was nine months (range, six to
twenty-five months).
High-energy proximal tibial fractures were treated with a staged protocol
consisting of temporary short-term external fixation followed by delayed open
reduction and internal fixation after soft-tissue recovery. Some distal
femoral fractures, such as those in polytraumatized patients, and open distal
femoral fractures were also treated with temporary external fixation. Patient
data are summarized in a table in the Appendix. The decision regarding the
timing of delayed open reduction and fixation was made by the treating
traumatologist. Open fractures were treated with emergent débridement,
prophylaxis against tetanus, and intravenous antibiotics. All patients were
given prophylactic intravenous antibiotics and mechanical and pharmacologic
prophylaxis against deep venous thrombosis.
Forty (71%) of the fifty-six fractures were treated with a percutaneous
technique and sixteen were treated with a traditional open technique
(visualization of the entire plate during implantation), with the technique
determined at the discretion of the treating surgeon. Additional posteromedial
plate fixation of the tibia was performed in seven patients who had a
displaced coronal split component of the posterior aspect of the medial tibial
plateau. This was the only indication for the use of double plates. Secondary
plates were not used to secure coronal plane stability but to neutralize shear
forces on displaced coronal fractures of the medial condyle. All available
periarticular screw holes were filled, and an average of four diaphyseal
screws were used.
Bone-grafting (with allograft croutons) of tibial metaphyseal defects was
performed for eleven fractures. Bone-grafting with allograft was performed for
five distal femoral fractures, four acutely and one at three months
postoperatively after a severe open fracture resulting in metaphyseal bone
loss. All patients with metaphyseal comminution or an intra-articular fracture
were limited to touch-down weight-bearing with crutches or a walker for twelve
weeks. Patients with a very proximal extra-articular tibial fracture were
typically allowed to progress to weight-bearing at six weeks if evidence of
progressing union was noted radiographically.
Radiographs were made at regular intervals and evaluated for
fracture-healing and any change in alignment (with use of a goniometer), screw
breakage, or screw back-out. Femoral alignment was assessed by measuring the
angle created by a line drawn along the femoral shaft and one drawn parallel
to the femoral condyles, with 5° of valgus considered to be normal. The
lateral radiograph was evaluated for procurvatum or recurvatum with use of
lines drawn along the main fragments. Tibial alignment in both planes was
measured by comparing lines drawn along the tibial shaft and parallel to the
articular surface. Attention was focused on whether there was any change in
the immediate postoperative alignment. Initial malalignment was defined as
angulation of >5° in any plane. Specific attention was given to the
immediate postoperative and final follow-up radiographs to identify any change
in periarticular fragment alignment suggestive of polyaxial screw drift.
Weight-bearing radiographs were made at the time of the last follow-up. The
articular reduction was also scrutinized for any visible settling or shift by
comparing the immediate postoperative and follow-up radiographs. A change of 2
mm was considered abnormal.
Clinical union was defined as a painless fracture site during full
weight-bearing. Radiographic union was defined as bridging trabeculation
across the fracture line(s) on three of four cortices seen on orthogonal
projections in the absence of migration, loosening, or breakage of
hardware.
Function at the time of follow-up was assessed with the Knee Society
criteria and reported as knee scores and function
scores22.
Specifics of Implant Design
The POLYAX distal femoral plate (Figs.
1 and
2) is composed of TiMAX
titanium alloy (titanium-6aluminum-4vanadium) (DePuy Trauma, Warsaw, Indiana)
manufactured with a proprietary anodization process. The head of the plate
contains a large, central, 8-mm fixed locking, cannulated screw. It is
designed to be inserted over a calibrated guide pin placed parallel to the
articular surface to provide 5° of valgus femoral alignment. Around the
periphery of this large central fixed-angle screw are multiple 5.5-mm
polyaxial screw holes that each contain a threaded bushing. These allow an
approximately 40° cone of angulation prior to end-point locking. As the
conical threaded head of the screw engages the bushing, the bushing expands,
placing hoop stresses on the surrounding hole and effectively locking the
screw. The shaft portion of the plate contains threaded round holes that can
accommodate fixed locking or standard large-fragment screws. A targeting
handle and specialized reduction instruments are provided for accurate
percutaneous insertion, if chosen. Diaphyseal screws can be unicortical or
bicortical, locked or unlocked.
The POLYAX proximal tibial plate is composed of the same titanium alloy. No
fixed locking screws are used; they are all polyaxial. The most proximal row
consists of three 4.0-mm solid polyaxial screws designed to provide
subchondral support in comminuted articular fractures by virtue of their
proximity to the articular surface. In the neck of the plate are 5.5-mm solid
polyaxial screws designed to provide coronal plane stability. The shaft
portion of the plate also accepts fixed locking or standard nonlocking screws.
Percutaneous instruments and targeting are available.
Forty-nine (94%) of fifty-two fractures had united at the time of the last
follow-up. There was one delayed union, of a closed bicondylar fracture of the
tibial plateau in a seventy-four-year-old man. That fracture was treated with
ultrasound stimulation (Exogen; Smith and Nephew, Memphis, Tennessee), and it
united by nine months. No polyaxial screw failed, and there were no cases of
varus collapse due to the loss of periarticular fixation. There were no plate
fractures. There was also no evidence of loss of fixation of any polyaxial
screw (i.e., no backing out and no change in the immediate postoperative
angulation).
One patient with massive metaphyseal bone loss from an open distal femoral
fracture underwent a planned delayed bone-grafting procedure at three months
after the injury. A distal femoral nonunion developed in another patient, who
had symptomatic preexisting knee arthritis, and that patient chose conversion
to total knee arthroplasty with an intramedullary stem instead of additional
attempts to secure fracture-healing. In this patient, the plate was well fixed
at the time of removal, with no evidence of screw loosening, toggle, or loss
of distal fixation.
No fractures were seen to be malaligned on the postoperative radiographs,
and only two demonstrated malalignment at the time of the last follow-up.
Lateral joint line collapse and a deep infection resulting in a nonunion and a
10° valgus deformity developed in a patient with an open bicondylar
fracture of the tibial plateau. Other than that patient, no patient (who
required joint elevation and reduction) exhibited settling of elevated
articular fragments. One patient, an alcoholic who did not comply with
postoperative instructions, fell postoperatively and bent the femoral plate in
an area of metaphyseal comminution. The distal fixation remained unchanged,
the alignment was felt to be acceptable, and the fracture healed in 5° of
varus. One patient who fell postoperatively and sustained a fracture proximal
to the femoral plate was treated successfully with an antegrade nail. No screw
cut out or broke. It should be noted that neither of the two patients who had
malalignment had evidence of failure of a polyaxial screw (Figs.
3-A and 3-B and
3-C, 3-D and 3-E).
Deep infection developed in three patients. An early postoperative
infection developed on one side in a seventy-seven-year-old woman with a
bilateral periprosthetic distal femoral fracture. This infection was treated
successfully with serial débridements. A deep infection also developed
in two patients with a bicondylar (OTA type 41C3) fracture of the tibial
plateau. One of them, a sixty-year-old patient with insulin-dependent diabetes
mellitus and a severe peripheral neuropathy, had an early postoperative deep
infection and chose an above-the-knee amputation instead of limb salvage. The
second patient initially had a Gustilo and
Anderson23 grade-3A
open fracture; a deep infection developed and was treated with wound
débridement, removal of hardware, and eventually osteoarticular
allograft reconstruction.
Therefore, overall, only three fractures failed to heal (two tibial
fractures with infection and one distal femoral fracture that was converted to
a total knee arthroplasty). Thus, the rate of aseptic nonunion in our series
was one (1.9%) of fifty-two and the rate of deep infection was three (5.8%) of
fifty-two, despite a high proportion of complex bicondylar, open, and
high-energy injuries. Two patients with a tibial plateau fracture exhibited
radiographic signs of lateral degenerative joint disease of the knee
(joint-space narrowing) at the time of the last follow-up.
The mean Knee Society knee score at the time of follow-up was 89 points
(range, 59 to 100 points), and the mean Knee Society function score was 82
points (range, 0 to 100 points).
There continue to be improvements in plate contour, specialized reduction
instruments, and surgeon experience with the techniques of percutaneous
locked-plate fixation of
fractures5,24.
Previously published series of fractures about the knee treated with
locked-plate technology demonstrated union and complication rates similar to
those in the current
study1,3,7-9,12,13,17,25-27.
Our results, in part, may have been due to the fact that experienced trauma
surgeons performed the operations. All of the surgeons had had extensive
experience with locked-plate fixation and were aware of the radiographic
vigilance necessary to obtain excellent intraoperative reductions. Immediately
after reduction and fixation, no fractures were malaligned and, other than in
the patient who fell and bent the plate and in the patient with an infected
tibial nonunion with lateral joint collapse, no malalignments were noted after
union had been achieved. It is intuitive that a well-aligned, well-reduced
fracture with hardware placed accurately in a biologically beneficial manner
should heal well, regardless of whether fixed-trajectory locking or polyaxial
screw technology is used. We do not know, for example, how forgiving polyaxial
technology would be if it was used for a fracture with massive metaphyseal
bone loss and malreduced in varus. It is unlikely, however, that any plate,
regardless of its strength, would fare well in this situation.
It should be noted that we did not select the POLYAX device for specific
fracture types for which we thought angulation of a screw would be necessary.
We used it as our locked plate of choice instead of a fixed-trajectory locked
plate. The purpose of this retrospective study was not to prove superiority of
polyaxial technology over fixed-trajectory locking technology, but to
determine whether a plate with polyaxial bushings that offers the opportunity
to angle a locking screw would perform as well as devices used in historical
controls without mechanical failure (i.e., varus drift or other potential
failure modes).
Another factor that perhaps contributed to our results was the ability that
this device offers to maximize periarticular fragment fixation by using
multiple screws or the ability to disperse screws in the end segment.
Fixed-trajectory locking screw-holes may be placed in areas of the plate
remote from the fragment that the surgeon wishes to stabilize. For example,
once a periarticular fixed-trajectory-angle plate is applied to the lateral
aspect of the tibia to treat a short bicondylar fracture of the tibial
plateau, the surgeon may be able to obtain purchase with only a few proximal
screws, since many of the screw-holes in the neck of the plate would be distal
to the primary fracture line. Polyaxial screws in the neck of the plate,
however, can be angled cephalad into the medial condylar component. This was
done frequently in the current series to maximize medial condylar fixation.
Additionally, polyaxial plates allow the surgeon to change the angle of the
locking screws in this region to accommodate patients of various sizes.
This series included a large proportion of high-energy fractures. We chose
locked plates for these fractures because of severe articular impaction and
the need for subchondral support in patients with poor bone quality. Simple
unicondylar fractures of the tibial plateau in patients with good bone stock
were treated with traditional unlocked plates. Nearly 80% of the proximal
tibial fractures treated in this study were bicondylar or comminuted. Despite
this fact, our union rates were quite high and our complication rates were
similar to those in earlier
series3,25-27.
It should be noted that only one patient exhibited settling of articular
fragments (the one with an infected bicondylar tibial nonunion). This may have
been due, in part, to the proximity of small-fragment polyaxial screws placed
in a subchondral support, or so-called raft, fashion. All bicondylar fractures
that demonstrated a displaced coronal medial condylar component were
approached with a two-incision technique. A posteromedial antiglide
small-fragment plate was typically applied first, followed by use of a lateral
locking plate. It is unlikely that any lateral device could neutralize the
shear forces on a posteromedial fragment during knee-flexion rehabilitation.
Recent data suggest that a coronal split is frequently present medially in
bicondylar tibial plateau
fractures28. It is
unlikely that a lateral locking plate alone will adequately stabilize a
posteromedial fragment. It is important to note that a posteromedial plate was
used to prevent fragment shear in flexion, not to provide coronal plane
stability. It is likely that the medial plates provided some coronal plane
support; however, these were small-fragment plates placed in antiglide mode,
and they probably provided only minimal off-loading of the lateral plate.
Additional studies are necessary to define the ideal fixation construct for
such coronal plane fractures.
Controversy will continue to surround the issue of what constitutes the
appropriate strength of any locked plate used for periarticular fixation. It
is likely, however, that, in the vast majority of cases, the implanted plate
is much stronger than the surrounding
bone5,29.
Compared with stainless steel, modern titanium alloys have demonstrated a
modulus of elasticity that is much closer to that of human bone, with an
improved fatigue life. These are both desirable features for periarticular
fixation. Zlowodzki et al. demonstrated, in a cadaver model, that the titanium
LISS plate (Synthes, Paoli, Pennsylvania) had more elastic deformation and a
greater maximum load to failure than did stainless-steel
plates30. The case
of our only patient with femoral fracture malalignment—i.e., the patient
who fell and bent the plate—confirms their conclusion that titanium
plates will bend before distal fixation is lost. This characteristic of
titanium-alloy plates may effectively unload some of the stresses on the
periarticular screws during loading; however, this theory remains unproven.
There have been reports of stiff stainless-steel locked plates with breakage
of cannulated periarticular locking screws. This is not surprising, given the
magnitude of cyclic implant loading during the healing and rehabilitation
phase of fractures around the
knee7,11,31.
Cannulation substantially weakens a screw, especially at the neck-shaft screw
junction. The shear forces experienced by multiple fixed-angle locked screws
stress this junction and may result in implant
breakage5,29.
The superior fatigue strength of anodized titanium alloy and the fact that the
polyaxial screws are not cannulated probably contributed to the absence of
hardware breakage in the current series.
This study had several shortcomings. The fact that multiple surgeons
treated various fracture types as well as the retrospective methodology make
it difficult to draw definitive conclusions. The femoral plate provides a
fixed locking large central screw, which may off-load the polyaxial screws to
some extent. Additionally, some tibial plateau fractures were treated with
double plates, and although the posteromedial plate was used to support
coronal articular fragments it undoubtedly provided some additional support
for the laterally placed fixation. Additionally, the follow-up was short, and,
although union could be documented in the vast majority of patients, late
complications such as posttraumatic arthritis, symptomatic hardware, or
problems with hardware removal could appear with longer follow-up.
We concluded that the polyaxial technology is effective in achieving high
rates of union without varus collapse or mechanical failure of well-reduced
complex fractures around the knee.
A table summarizing data on all study patients is available with the
electronic versions of this article, on our web site at
(go to
the article citation and click on "Supplementary Material") and on
our quarterly CD-ROM (call our subscription department, at 781-449-9780, to
order the CD-ROM). ?
Cole PA, Zlowodzki M, Kregor PJ.
Treatment of proximal tibia fractures using the less invasive stabilization
system (LISS): surgical experience and early clinical results in 77 fractures.
J Orthop Trauma. 2004;18:
528-35.18528
2004
[PubMed][CrossRef]
Collinge CA, Sanders RW. Percutaneous
plating in the lower extremity. J Am Acad Orthop Surg.
2000;8:
211-6.8211
2000
[PubMed]
Egol KA, Su E, Tejwani NC, Sims SH,
Kummer FJ, Koval KJ. Treatment of complex tibial plateau fractures using the
less invasive stabilization system plate: clinical experience and a laboratory
comparison with double plating. J Trauma.
2004;57:
340-6.57340
2004
[PubMed][CrossRef]
Frigg R, Appenzeller A, Christensen R,
Frenk A, Gilbert S, Schavan R. The development of the distal femur Less
Invasive Stabilization System (LISS). Injury.
2001;32Suppl 3:
SC24-31.32SC24
2001
[PubMed]
Haidukewych GJ. Innovations in locking
plate technology. J Am Acad Orthop Surg.
2004;12:
205-12.12205
2004
[PubMed]
Jazrawi LM, Kummer FJ, Simon JA, Bai B,
Hunt SA, Egol KA, Koval KJ. New technique for treatment of unstable distal
femur fractures by locked double-plating: case report and biomechanical
evaluation. J Trauma.
2000;48:
87-92.4887
2000
[PubMed][CrossRef]
Kregor PJ. Distal femur fractures with
complex articular involvement: management by articular exposure and
submuscular fixation. Orthop Clin North Am.
2002;33:
153-75.33153
2002
[PubMed][CrossRef]
Kregor PJ, Hughes JL, Cole PA. Fixation
of distal femoral fractures above total knee arthroplasty utilizing the Less
Invasive Stabilization System (L.I.S.S.). Injury.
2001;32Suppl 3:
SC64-75.32SC64
2001
[PubMed]
Kregor PJ, Stannard JA, Zlowodzki M,
Cole PA. Treatment of distal femur fractures using the less invasive
stabilization system: surgical experience and early clinical results in 103
fractures. J Orthop Trauma.
2004;18:
509-20.18509
2004
[PubMed][CrossRef]
Krettek C, Müller M, Miclau T.
Evolution of minimally invasive plate osteosynthesis (MIPO) in the femur.
Injury. 2001;32Suppl 3: SC14-23.32SC14
2001
[PubMed]
Marti A, Fankhauser C, Frenk A, Cordey
J, Gasser B. Biomechanical evaluation of the less invasive stabilization
system for the internal fixation of distal femur fractures. J Orthop
Trauma. 2001;15:
482-7.15482
2001
[CrossRef]
Schandelmaier P, Partenheimer A,
Koenemann B, Grün OA, Krettek C. Distal femoral fractures and LISS
stabilization. Injury.
2001;32Suppl 3:
SC55-63.32SC55
2001
[PubMed][CrossRef]
Schütz M, Müller M, Krettek C,
Hontzsch D, Regazzoni P, Ganz R, Haas N. Minimally invasive fracture
stabilization of distal femoral fractures with the LISS: a prospective
multicenter study. Results of a clinical study with special emphasis on
difficult cases. Injury.
2001;32Suppl 3:
SC48-54.32SC48
2001
[PubMed]
Stover M. Distal femoral fractures:
current treatment, results and problems. Injury.
2001;32Suppl 3:
SC3-13.32SC3
2001
[PubMed]
Farouk O, Krettek C, Miclau T,
Schandelmaier P, Guy P, Tscherne H. Minimally invasive plate osteosynthesis:
does percutaneous plating disrupt femoral blood supply less than the
traditional technique? J Orthop Trauma.
1999;13:
401-6.13401
1999
[PubMed][CrossRef]
Perren SM. Evolution and rationale of
locked internal fixator technology. Introductory remarks.
Injury. 2001;32Suppl 2: S-B3-9.32S-B3-9
2001
Althausen PL, Lee MA, Finkemeier CG,
Meehan JP, Rodrigo JJ. Operative stabilization of supracondylar femur
fractures above total knee arthroplasty: a comparison of four treatment
methods. J Arthroplasty.
2003;18:
834-9.18834
2003
[PubMed][CrossRef]
Bong MR, Egol KA, Koval KJ, Kummer FJ,
Su ET, Iesaka K, Bayer J, Di Cesare PE. Comparison of the LISS and a
retrograde-inserted supracondylar intramedullary nail for fixation of a
periprosthetic distal femur fracture proximal to a total knee arthroplasty.
J Arthroplasty. 2002;17:
876-81.17876
2002
[PubMed][CrossRef]
Kaab MJ, Frenk A, Schmeling A, Schaser
K, Schutz M, Haas NP. Locked internal fixator: sensitivity of screw/plate
stability to the correct insertion angle of the screw. J Orthop
Trauma. 2004;18:
483-7.18483
2004
[CrossRef]
Richter M, Wilke HJ, Kluger P, Claes L,
Puhl W. Biomechanical evaluation of a newly developed monocortical expansion
screw for use in anterior internal fixation of the cervical spine. In vitro
comparison with two established internal fixation systems.
Spine. 1999;24:
207-12.24207
1999
[PubMed][CrossRef]
Fracture and dislocation compendium. Orthopaedic Trauma Association
Committee for Coding and Classification. J Orthop Trauma.
1996;10Suppl 1:
v-ix, 1-154.10v
1996
[PubMed]
Insall JN, Dorr LD, Scott RD, Scott WN.
Rationale of the Knee Society clinical rating system. Clin Orthop Relat
Res. 1989;248:
13-4.24813
1989
Gustilo RB, Anderson JT. Prevention of
infection in the treatment of one thousand and twenty-five open fractures of
long bones: retrospective and prospective analyses. J Bone Joint Surg
Am. 1976;58:
453-8.58453
1976
Schatzker J. Changes in the AO/ASIF
principles and methods. Injury.
1995;26Suppl 2:
SB51-6.26SB51
1995
[CrossRef]
Ertl WJ, Smith DG. Bicondylar
tibial plateau fractures: comparison of early results with a locking plate
compared with medial and lateral plating. Read at the Annual Meeting
of the Orthopaedic Trauma Association; 2002Oct12; Toronto, Ontario, Canada.
2002
Gosling T, Schandelmaier P, Marti A,
Hufner T, Partenheimer A, Krettek C. Less invasive stabilization of complex
tibial plateau fractures: a biomechanical evaluation of a unilateral locked
screw plate and double plating. J Orthop Trauma.
2004;18:
546-51.18546
2004
[PubMed][CrossRef]
Gosling T, Schandelmaier P, Müller
M, Hankemeier S, Wagner M, Krettek C. Single lateral locked screw plating of
bicondylar tibial plateau fractures. Clin Orthop Relat Res.
2005;439:
207-14.439207
2005
[PubMed][CrossRef]
Barei DP, O'Mara T, Falicov A, Taitsman
LA, Nork SE. The tibial less invasive stabilization system (LISS) and
its relationship to the posteromedial fragment in bicondylar tibial plateau
fracture patterns. Read at the Annual Meeting of the Orthopaedic
Trauma Association; 2005Oct22;
Ottawa, Ontario, Canada.
2005
Egol KA, Kubiak EN, Fulkerson E, Kummer
FJ, Koval KJ. Biomechanics of locked plates and screws. J Orthop
Trauma. 2004;18:
488-93.18488
2004
[CrossRef]
Zlowodzki M, Williamson S, Cole PA,
Zardiackas LD, Kregor PJ. Biomechanical evaluation of the less invasive
stabilization system, angled blade plate, and retrograde intramedullary nail
for the internal fixation of distal femur fractures. J Orthop
Trauma. 2004;18:
494-502.18494
2004
[CrossRef]
Vallier HA, Hennessey TA, Sontich JK,
Patterson BM. Failure of LCP condylar plate fixation in the distal part of the
femur. A report of six cases. J Bone Joint Surg Am.
2006;88:
846-53.88846
2006
[PubMed][CrossRef]