Abstract
Background: The most effective type of plate fixation for diaphyseal
forearm fractures has not been defined. We performed a prospective, randomized
trial in which the limited contact dynamic compression plate (LC-DCP) was
compared with the Point Contact Fixator (PC-Fix) for the treatment of forearm
fractures at one center.
Methods: Ninety-two patients with 125 forearm fractures were
recruited for the study and were randomly assigned to fracture fixation with
one of the two devices. The average age of the patients was thirty-six years.
The average duration of follow-up was twenty-two months. Patients were
assessed periodically with use of radiographs and were assessed with regard to
pain and function at time of the latest follow-up.
Results: Three patients (four fractures) in the PC-Fix group and
five patients (five fractures) in the LC-DCP group had a delayed union, but no
patient in either group had a nonunion. With the numbers available, there was
no significant difference between the two groups with regard to operative
time, time to union, callus formation, pain, or functional outcome. Deep
infection occurred in one patient with a closed fracture in the PC-Fix group
and in one patient with an open fracture in the LC-DCP group. In addition, one
refracture occurred in each group. Both refractures occurred at the site of a
screw track.
Conclusion: Despite the differences in the concept of fracture
fixation, these two implants appear to be equally effective for the treatment
of diaphyseal forearm fractures.
Level of Evidence: Therapeutic study, Level I-1b
(randomized controlled trial [no significant difference but narrow confidence
intervals]). See Instructions to Authors for a complete description of levels
of evidence.
It is known that anatomical reduction and rigid fixation in an attempt to
achieve primary bone-healing may delay union as a result of excessive
soft-tissue and periosteal stripping. Hence, over the past decade, there has
been an increasing emphasis on the concept of "biological
fixation" for the treatment of long-bone
fractures1.
With conventional plating, the screw acts as an anchor, with its axial
force being exploited to press the plate against the bone. This produces a
large frictional force at the bone-plate interface when the construct is
loaded, and this force has been shown to cause vascular disturbance,
especially in the
periosteum2. This
observation prompted the development of the limited contact dynamic
compression plate (LC-DCP), which decreases the bone-contact area to
approximately 50% of the total area of the undersurface of the plate.
However, with the LC-DCP device, the problem of confluent contact areas is
not completely resolved. To further reduce contact between the bone and the
fixator, the Point Contact Fixator (PC-Fix) was developed
(Fig. 1). This device does not
have surface contact with the bone but has only point contacts. In addition,
conventional long and bicortical screws are replaced with monocortical screws,
which lock into the screw-hole on the plate and do not engage the far
cortex3. In simple
terms, with conventional plates (such as the LC-DCP), the screws are locked
into the bone, whereas with the PC-Fix device, the screws are locked into the
plate.
The potential advantages of the PC-Fix system include a reduced risk of
infection as a result of better vascularity, an increased rate of healing, and
a reduced risk of refracture when the implant is
removed2. However,
all of these advantages remain theoretical, calling for a randomized, clinical
trial comparing this device with a conventional plate. Despite support from
animal studies and mechanical
testing2, reports of
well-planned clinical trials of the PC-Fix device are lacking.
The purpose of the present study was to test the hypothesis that use of the
PC-Fix device for the treatment of diaphyseal fractures of the forearm results
in better bone-healing and decreased complications in terms of infection and
refracture as compared with use of the LC-DCP device. Diaphyseal fractures of
the forearm were studied because plating is still considered to be the best
method of fixation for such fractures.
All patients with an age of more than ten years who had an acute diaphyseal
forearm fracture were considered for inclusion in the study. We excluded
patients who had a pathological fracture, those who had rheumatoid arthritis
or a history of long-term steroid therapy, and those who were unable or
unlikely to complete the course of follow-up. Four patients who were eligible
for the study refused enrollment. The study was approved by the ethics
committee of the hospital. Consent for participation in the study was obtained
from each patient, and a legal valid representative was required if the
patient was less than eighteen years old. The fixation was performed after
randomization. For the initial thirty-two cases, an open, predetermined
randomization chart was used. The chart was constructed of blocks containing
four allocations, with each block containing two PC-Fix fixations and two
LC-DCP fixations. For the subsequent cases, the choice of fixation was
determined in a strictly alternating fashion. The entries into both the block
randomization chart and the alternating chart were done according to the
chronological order of admission. In order to ensure compliance with the
randomization, the research committee of the institute reviewed these charts
periodically. Between August 1996 and January 2001, ninety-three patients who
were admitted with a forearm fracture were recruited into the study. One
patient refused to participate after randomization, leaving ninety-two
patients available for study. Sixteen patients were female, and seventy-six
were male. The average age was thirty-six years (range, eleven to ninety
years). Seven patients in the PC-Fix group and nine in the LC-DCP group were
under the age of eighteen years.
The PC-Fix group included forty-five patients, and the LC-DCP group
included forty-seven patients. These ninety-two patients had a total of 125
fractures, including sixty-five fractures of the shaft of radius and sixty
fractures of the shaft of ulna (Table
I). Fifty-nine fractures were treated with the PC-Fix device, and
sixty-six were treated with the LC-DCP device.
The fractures were classified according to the AO classification system.
Seventy-one fractures (57%) were the result of low-energy trauma, and
fifty-four (43%) were the result of high-energy trauma. Seventy-five patients
(82%) had an isolated forearm fracture, sixteen (17%) had multiple fractures,
and one had polytrauma. Seventeen patients (18%) had an open fracture; of
these, eleven had a grade-I injury according to the classification system of
Gustilo and
Anderson4, four had
a grade-II injury, and two had a grade-III injury. Eight of these patients had
PC-Fix fixation, and nine had LC-DCP fixation.
Three patients had a radial nerve injury that was diagnosed preoperatively.
One of them had a completely transected nerve, which was repaired at the time
of fixation. In a second patient, the radial nerve injury was the result of a
concomitant fracture of the ipsilateral humeral shaft. Two patients had a
vascular injury. In one, both radial and ulnar arteries were repaired and, in
the other, the ulnar artery was ligated. There were no vascular sequelae in
these two patients.
All patients were admitted to the hospital. Fracture fixation was performed
by one of two surgeons (F.L. or S.P.C.), both of whom had previous experience
with the use of both implants. In six patients, fixation was delayed for more
than one week. A single injection of 1 g of cefazolin was given immediately
before each operation. The 3.2-mm PC-Fix (Mathys Medical, Bettlach,
Switzerland) and the 3.5-mm LC-DCP (Mathys Medical) were used as they are both
made of titanium and have almost identical mechanical
properties5.
Reduction through direct fracture manipulation with use of pointed clamps was
used for 83% of the fractures in the PC-Fix group and for 93% of those in the
LC-DCP group. The rest of the fractures were reduced indirectly with the aid
of a distraction device. The amount of periosteal stripping was kept to the
minimum amount required in both groups.
The operative time, the amount of periosteal stripping, and intraoperative
complications such as stripping of a screw were noted. The surgeon was asked
to report on the ease of the procedures and whether he would have preferred to
use the other implant. All patients were followed in a special research
clinic, and radiographs were made at three to four-week intervals until there
was evidence of fracture union. Complete outcome assessments were performed at
two, four, and twelve months and at a long-term follow-up interval (defined as
eighteen months after the first operation or six months after plate removal).
The average duration of follow-up was twenty-two months (range, fourteen to
forty months). The long-term follow-up rate was 89%.
Statistical Analysis
Statistical analysis was performed with use of two tests. The Student t
test was used to compare the operative times for the two groups. Pearson
chi-square analysis was performed to compare the groups with regard to callus
formation, the range-of-motion score, and the pain score. Differences were
considered to be significant when the p value was <0.05.
Operative Time
The mean operative time was seventy-eight minutes (range, thirty to 300
minutes) for the PC-Fix group, compared with ninety-two minutes (range, thirty
to 180 minutes) for the LC-DCP group. These times were not significantly
different (p = 0.06).
Fracture Union
Union was assessed radiographically and was defined as complete
obliteration of the fracture gap on two views. Delayed union was defined as
the presence of the fracture gap or the absence of progressive callus
formation within six months (or more) postoperatively. Twenty-one percent of
the fractures healed by twelve weeks, 62% healed by sixteen weeks, 82% healed
by twenty weeks, and 93% healed by twenty-four weeks. There were no nonunions.
Three patients (four fractures) in the PC-Fix group and five patients (five
fractures) in the LC-DCP group had a delayed union, but all fractures
proceeded to union (Table II).
The mean time to union in the PC-Fix group was eighteen weeks (range, eight to
forty-four weeks) for closed fractures and twenty weeks (range, twelve to
forty weeks) for open fractures, and the mean time to union in the LC-DCP
group was seventeen weeks (range, eight to thirty-six weeks) for closed
fractures and seventeen weeks (range, twelve to twenty-four weeks) for open
fractures.
Quality of Reduction and Callus Formation
Radiographs were studied by an independent observer to determine whether
the fractures were anatomically reduced. The fracture was considered to be
anatomically reduced if precise anatomical alignment had been achieved and
wedge fragments had been reduced and fixed with lag screws. The fracture was
considered to be nonanatomically reduced if the main fragments had been
aligned but precise anatomical reduction of fragments had not been achieved.
Forty-two percent of the fractures in the PC-Fix group and 42% of those in the
LC-DCP group were reduced anatomically, and the others were not.
Callus formation at the fracture site was evaluated by the examiner
radiographically and was categorized as no callus, minimal callus, moderate
callus, or abundant callus. In the PC-Fix group, 59% of the fractures healed
with no or minimal callus formation, 29% healed with moderate callus
formation, and 12% healed with abundant callus formation. In the LC-DCP group,
59% of the fractures healed with no or minimal callus formation, 32% healed
with moderate callus formation, and 9% healed with abundant callus formation.
With the numbers available, there was no significant difference between the
two groups when the corresponding subgroups were compared (p > 0.05).
After anatomical reduction, moderate or abundant callus formation occurred
at the site of 16% of the fractures in the PC-Fix group and 24% of the
fractures in the LC-DCP group. There was no significant difference between the
two groups. After nonanatomical reduction, moderate or abundant callus
formation occurred at the site of 59% of the fractures in the PC-Fix group and
54% of the fractures in the LC-DCP group. Within both the PC-Fix group and the
LC-DCP group, there were significant differences between fractures that had
been reduced anatomically and those that had been reduced nonanatomically with
regard to the presence of callus (p = 0.001 and 0.014, respectively;
chi-square test).
Outcome Measures
In the present study, the range of motion as determined according to the
method of Anderson et
al.6 was used as a
measure of functional outcome. The results for the two groups are shown in
Table III. Pain was assessed
according to its effect on activity and the requirement for medication. The
results for the two groups are shown in
Table IV.
With the numbers available, there was no significant difference between the
LC-DCP group and the PC-Fix group with regard to the range of motion score (p
= 0.07) or the pain score (p = 0.10).
Implant Removal
At the time of the final follow-up, twenty-two PC-Fix and twenty-nine
LC-DCP devices had been removed from thirty-seven patients. The average
interval between insertion and removal was fifteen months (range, eight to
twenty-three months). In the LC-DCP group, half of the implants were covered
with a thick fibrous layer whereas the others were covered with a thin fibrous
layer. The tissue was found to adhere to the implant in the majority of cases.
In the PC-Fix group, the implants were commonly covered with a thin,
nonadherent layer of fibrous tissue. The bone under both types of implants was
noted to be well vascularized, with numerous bleeding points in the majority
of cases. The bone under the PC-Fix devices was covered with a smooth
periosteum. However, under the LC-DCP devices, there appeared to be more
tissue reaction, with fibrous tissue ingrowth around the screw-holes.
Complications (Table
V)
One deep infection occurred in each group. In the LC-DCP group, an
infection occurred two weeks postoperatively in a thirty-five-year-old man who
had a Gustilo grade-I open fracture of the left ulna. The infection subsided
after surgical débridement and antibiotic treatment; the implant was
not removed. In the PC-Fix group, an infection with Staphylococcus
aureus developed two weeks postoperatively at the site of an ulnar
fracture in a twenty-four-year-old woman who had closed fractures of both
bones. The ulnar fracture gradually healed with splinting after removal of the
implant during the third week.
Pulling out of screws from the ulna was noted at three months
postoperatively in a sixty-three-year-old woman with open fractures of the
radius and ulna that had been treated with the PC-Fix device
(Fig. 2). Union was achieved
without additional splinting.
Two refractures occurred after implant removal. One refracture occurred in
the PC-Fix group at six months after implant removal
(Fig. 3), and the other
occurred in the LC-DCP group at two months after implant removal. Both
fractures occurred at the sites of screw tracks, and both healed with
immobilization.
Open reduction and plate fixation has been the most accepted method of
treatment of forearm fractures. In 1975, Anderson et
al.6 reported union
rates of 98% for fractures of the radius and 96% for fractures of the ulna. An
excellent or satisfactory result was achieved in 86% of the patients. Chapman
et al.7, in 1989,
reported that 92% of their patients had an excellent or satisfactory
functional result. The rate of infection was 2.3%.
The results of the present study are similar to those reported in the
literature6-8.
Despite the fact that the PC-Fix and the LC-DCP use different concepts of
fixation, both implants were shown to be effective for the treatment of
diaphyseal forearm fractures. The present study showed that the pattern of
bone-healing was affected by the quality of fracture reduction rather than by
the type of implant used. When anatomical reduction was achieved, there was
minimal callus formation in either group. Our findings support the view of
Tepic and Perren3
that the mechanical performance of the PC-Fix is comparable with that of
conventional plates.
The concept of plate fixation is based on stress-shielding in preventing
displacement of the fracture. This may cause atrophy or porosis in the segment
of bone to which a plate is applied. In the literature, the risk of refracture
after removal of a plate has been reported to be 4% to
25%6,7,9,10.
The overall prevalence in our study was 4%. One interesting point to note is
that both refractures in our series occurred at old screw tracks, suggesting
that the removal of a monocortical screw still can create a potential weak
point in the bone.
With the numbers available, the present study does not support the
hypothesis that use of the PC-Fix device decreases the prevalence of
complications as compared with use of the LC-DCP device. Both devices were
associated with very low complication rates. Fixation with use of the PC-Fix
device involves unicortical screws and seems to be a quicker procedure;
however, no significant difference was detected with regard to operative
time.
The current study was limited by the method of randomization. Ideally, the
envelopes containing the implant allocation should have been opened just
before scrubbing. The implant choice was already known before the subjects
were recruited, which might have led to bias in terms of patient selection and
surgeon preference. Hence, we limited the study to operations that had been
performed by two experienced surgeons. In nearly all cases, the surgeons
reported the same amount of ease or difficulty with both implants.
Another problem associated with the present study was related to the
radiographic evaluation. During the assessment of bone union, the fracture gap
may be unnoticeable even immediately after surgery, especially in patients
with an anatomical reduction. Moreover, in some views, the implant may cover
up a wide portion of the bone, making interpretation more difficult.
Nevertheless, we reviewed all of the radiographs and attempted to assess bone
union. The interpretation of reduction quality and callus formation, even by
an independent observer, is also subject to bias as the type of implant is
evident on the radiographs.
Finally, we believe that a fair comparison between the two devices in terms
of union and outcome measures cannot be made without comparing each AO
fracture subgroup. The number of cases in our study, however, did not support
this analysis. Clearly, a more definitive conclusion would necessitate a
multicentered trial involving a large series of patients. We conclude that,
with the number of patients studied, these two implants appear to be equally
effective for the surgical treatment of diaphyseal forearm fractures.
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