Study Design
This randomized, prospective, active, concurrently controlled clinical
trial was initiated in January 1995 to evaluate the treatment outcomes of
matched cohorts of patients with distal radial fractures managed with either
Norian SRS cement (study) or conventional (control) treatment. A total of 323
patients were enrolled at twenty-three investigative centers. The
institutional review board at each center approved the study protocol and
randomization process. The investigators were required to attend a bioskills
workshop on the application of Norian SRS cement. A detailed consent form was
signed by each patient prior to enrollment.
Patient Selection
Patients who sustained a displaced and/or unstable (comminuted) distal
radial fracture and were at least forty-five years old and living
independently were considered for inclusion in the study. All patients were
volunteers. Inclusion and exclusion criteria were intended to limit the distal
radial fractures to isolated, low-energy displaced fractures that would
require manipulative reduction and some form of immobilization. The inclusion
and exclusion criteria are listed in the Appendix.
Randomization
The patients were assigned to a treatment group (SRS or conventional
therapy) according to a stratified and blocked randomization schedule designed
to ensure matching and balance between the groups at each site and overall.
The randomization was based on four parameters: fracture type (intra-articular
or extra-articular), bone mineral density (average or below average), side of
injury (dominant or nondominant hand), and the type of designated conventional
immobilization (cast or external fixator). The fracture type was classified as
intra-articular if any fracture line extended into the radiocarpal or distal
radioulnar joint. The Older et
al.11,
Frykman12, and
comprehensive
AO/ASIF13
classification systems were used to further define the fracture. Bone mineral
density was determined by dual-x-ray absorptiometry of the uninjured distal
radius. Patients were classified as having either "average"
(values of =0.57
g/cm2)14
or "below average" bone quality. The involved limb was defined as
dominant or nondominant. The fourth randomization parameter was the
designation of a cast or an external fixator for immobilization. For each
fracture, the investigator preoperatively assigned his or her preferred
control treatment. Fractures that then were randomized to the control group
received the preselected treatment (cast or external fixator). Fractures that
were randomized to the study group and received SRS cement received a
designation indicating which form of conventional treatment they would have
received had they been randomized to the control group (SRS-designated cast or
SRS-designated external fixator). This randomization method was implemented to
attempt to control for fracture severity while permitting the investigator to
treat the control subjects with his or her preferred method.
Sample Size
Radial length and grip strength
data15-17
were used to perform a power
analysis18. In
order to detect a mean difference (and standard deviation) in radial length of
0.75 ± 1.9 mm and a mean grip strength difference of 5% ± 10%
with 90% power, a sample size of 145 patients per treatment group was needed.
A target of 162 enrolled patients per treatment group was adopted to
accommodate an assumed 10% attrition rate.
Treatment
All procedures were performed in the operating room with the patient under
regional or general anesthesia, within five days after the injury. SRS
treatment included a closed reduction under image intensification, followed by
injection of SRS cement into the metaphyseal bone defect either through a
dorsal percutaneous8
or a limited open technique. Early in the study, the percutaneous method was
favored for its apparent simplicity. However, many investigators had
difficulty injecting the cement into the fracture site, encountering
obstructions such as hematoma, cancellous bone fragments, and inadequate space
in which to inject. In addition, the rate of extravasation was quite high.
Consequently, beginning with the thirteenth study patient, a limited open
technique was used exclusively. A 1.5 to 2-cm dorsal incision was made
directly over the metaphyseal component of the fracture between the third and
fourth extensor compartments under tourniquet hemostasis. The so-called
fracture void was prepared by evacuating the fracture hematoma and impacting
the crushed metaphyseal bone to a stable rim with a small elevator or tamp.
The cement was then injected under fluoroscopic control, excess cement was
removed with a sponge, and the tourniquet was then released. The limb was not
manipulated for ten minutes to allow the cement to set. The wound was closed,
and a short arm cast was worn for two weeks. The patient then wore a removable
splint for four additional weeks.
Supplemental Kirschner-wire fixation was permitted in specific instances,
including displaced articular fractures that remained unstable following
reduction or nondisplaced articular fractures at risk of displacement during
injection. The wires were intended to be used to resist only noncompressive
loads (shearing or tensile forces) and were not to be used as the principal
fixation of the metaphyseal component of the fracture. Intrafocal
(Kapandji)19
pinning was not permitted. The protocol specified that the Kirschner wires be
placed prior to SRS injection and that they be maintained for a minimum of
twenty-four hours to avoid disruption of the cement during its curing
period.
The control group underwent a closed reduction of the fracture, followed by
the application of a short arm cast or an external fixator, depending on the
preference of the individual investigator. Percutaneous pins were placed at
the discretion of the investigator according to previously described
methods20-22;
any configuration except intrafocal pinning was permitted. Immobilization was
discontinued at six to eight weeks postoperatively, as determined by the
treating surgeon.
Prior to discharge, all patients were instructed in digital range-of-motion
exercises and limb elevation to reduce edema. Occupational therapy, including
wrist and forearm range-of-motion exercises, was initiated at two weeks for
the SRS group and at the time of removal of the cast or external fixator for
the control group.
Evaluations
Follow-up evaluations were specified at one, two, four, and between six and
eight weeks, and at three, six, and twelve months after treatment for all
patients. At each visit, designated subjective, objective, and radiographic
data were obtained, and complications were recorded.
Clinical Evaluation
The patient was asked to assess both wrist pain and hand function with use
of a visual analog scale at each follow-up visit. Interim pain medication
usage was documented. During follow-up evaluations at one week and six to
eight weeks and at six and twelve months, the patient completed the standard
validated Short Form-36 (SF-36) health status
questionnaire23,24.
Functional measurements of digital, wrist, and forearm motion were obtained
at each visit by designated occupational therapists with use of standardized
techniques25. Grip
strength was measured with use of the Jamar dynamometer (Therapeutic
Equipment, Clifton, New Jersey) at the six to eight-week and the three, six,
and twelve-month follow-up visits. Edema was measured in both groups at the
one, two, and six to eight-week follow-up intervals. Circumferential
measurements were obtained at the forearm (10 cm distal to the olecranon
process), wrist, and proximal and middle phalanx of each finger. For patients
managed with a cast, the wrist and forearm measurements began at the time of
cast change or removal. Digital circumferences were averaged for the proximal
and middle phalanx. Edema was expressed as a percentage of the measurements of
the contralateral limb.
The Jebsen dexterity
test26 was
administered at the six to eight-week and the three, six, and twelve-month
intervals. The time needed to perform each activity was recorded and compared
with that for the uninjured limb. The clinical outcome at twelve months was
also assessed with use of the scoring system of Green and
O'Brien27, as
modified by Cooney et
al.28. In this
100-point scale, pain, functional status, range of motion, and grip strength
are assigned equal weight. The visual analog scale for pain was used to
calculate the pain score.
Radiographic Evaluation
Standard posteroanterior and lateral radiographs were made at each
follow-up visit. Independent bone radiologists reviewed the radiographs and
measured radial
length29, radial
angle (ulnar
inclination)29-33,
volar/dorsal
angle31,32,
ulnar variance34,
radial
shift30-32,35,
and articular
step-off36.
Radiographic parameters were compared with those of the uninjured wrist, with
the difference expressed as the change in millimeters or degrees as
appropriate.
Radiographic criteria were established for assessing failure (loss of
reduction). These included a change in the radial length of >5 mm compared
with the contralateral side, a dorsal angle of >10° and/or a change in
the volar/dorsal angle of >20°, and an articular step-off of >2 mm.
Patients who had loss of reduction were considered to have had a treatment
failure, and they were considered in the final analysis regardless of whether
any secondary interventions had been required.
Statistical Methods
Statistical analysis was completed with the SAS statistical software
package (version 6.12; SAS Institute, Cary, North Carolina), the JMP
statistical software package (version 3.2.1; SAS Institute), and StatXact
(version 4; Cytel Statistical Software, Cambridge, Massachusetts). Demographic
characteristics of the study groups were compared with the use of univariate
analysis of variance for the continuous variables and with the use of chi
square for the categorical variables. Univariate analyses of variance were
used to identify differences between treatment groups with respect to
functional and radiographic outcome, swelling, pain, use of pain medication,
and health survey results. To control for possible confounding factors,
covariate adjustment was used for study stratification and demographic biasing
variables. Repeated-measures analysis of variance with covariate adjustment
was used to compare the study groups over time with respect to functional and
radiographic outcomes. The adverse events of the two study groups were
compared with the use of chi-square and Fisher exact tests. The frequencies of
individual and combined radiographic failure and individual and combined
functional failure as well as overall failure, including reoperations, were
calculated as exact binomial confidence intervals. All failure frequencies of
the study groups were compared with the use of the Fisher exact test. Logistic
regression with covariates was used to analyze the influence of covariates in
the failure analysis. All reported p values are two-sided; p values of
<0.05 were considered to be significant.
Patient Cohort
A total of 323 patients were enrolled in the study. Of those patients, 161
were randomized to treatment with Norian SRS (study patients) and 162 were
randomized to conventional treatment (control subjects)
(Table I). Two hundred and
seventy-two patients (84%) were women and fifty-one (16%) were men, and the
average age was sixty-four years. With the exception of gender, no differences
were identified between the treatment groups. The proportion of women in the
control group (88%) was higher than that in the SRS group (80%) (p = 0.04).
Comorbidities were comparable. Nearly 90% of the total study population was
white, and no differences with respect to race were noted between the two
groups.
The numbers of intra-articular fractures were equivalent for both groups,
with seventy-five intra-articular fractures in the study group and
seventy-three in the control group (p = 0.78). In addition, no significant
differences between groups were noted with respect to the fracture types
classified by any of the three methods
(Table II).
The study period required for the enrollment of 323 patients was 881 days.
A rigorous attempt was made to follow all patients for twelve months. There
were a total of thirty-eight deviations from the established patient selection
criteria in thirty-four patients. These deviations were fairly evenly
distributed across the two treatment groups. Nineteen patients (eleven in the
study group and eight in the control group) were treated more than five days
(range, six to nine days) following the injury. Eight individuals were less
than forty-five years old: one, who was 44.9 years old, was in the study group
and seven, who ranged from 28.9 to 44.9 years old, were in the control group.
In four patients (two in each group), the reduction criteria were not met. Six
patients (five in the study group and one in the control group) had either a
more complex distal radial fracture than initially thought and/or an
ipsilateral ligament or skeletal injury. One patient provided only a verbal
consent to the study protocol, and one other subject (in the control group)
was taking Didronel (etidronate disodium) to treat osteoporosis.
Among the 323 patients, eight study patients and seven control patients
were lost to follow-up as they did not return for evaluations and were unable
to be reached by telephone or letter. Six study patients and five control
patients voluntarily withdrew from the study. Two study patients and one
control patient died during the study from causes unrelated to the fracture or
surgery. Thus, overall, 10% of the study patients and 8% of the control
patients did not complete the study, with six patients lost before the six to
eight-week follow-up examination, six more lost before three months, seven
more lost before six months, and the final ten lost before twelve months.
Subjective Evaluation
The study patients reported less pain on the average than the control
patients did at all follow-up visits, with a significant difference at two
weeks (p = 0.02) and four weeks (p = 0.02). On the average, the study patients
required less postoperative pain medication than the control patients did at
all follow-up visits. The differences were significant only at two weeks (p =
0.004). The patient-reported rating of the use of the hand was significantly
greater for the study patients at both four weeks (p = 0.007) and six weeks (p
= 0.0001) compared with that of the control patients. No other significant
differences were observed.
The SF-36 health status questionnaire showed significant differences in
function at the six to eight-week time-point. The study patients scored
significantly higher than the control patients did in five of the eight
domains, including fewer limitations due to pain, less limitation of role due
to physical or emotional problems, a better state of mental health, and an
improved ability to perform normal social activities (p < 0.05). No other
significant differences were noted at any other time-points.
Objective Evaluation
At six to eight weeks, the study patients exhibited a greater mean grip
strength than did the control patients (18 lb [8 kg] compared with 10 lb [4.5
kg], or 37% compared with 21.5% of that of the contralateral side,
respectively) (p < 0.0001). The study patients also demonstrated a greater
mean range of wrist and forearm motion in all planes at this time-point (see
Appendix). By three months, grip strength and wrist motion parameters were
equivalent for the two groups. The average grip strength and motion continued
to increase in both groups at similar rates for the remainder of the study
period.
Digital range of motion, which was first assessed at the six to eight-week
time-point, was better in the study patients. Metacarpophalangeal, proximal
interphalangeal, and distal interphalangeal joint motion in the fingers, and
carpometacarpal and metacarpophalangeal motion in the thumb were all greater
at this time-period (p < 0.01). At three months, significantly better
distal interphalangeal joint motion was observed in the study group (p =
0.015). No other significant differences between groups were noted.
At two weeks, the study patients had significantly less forearm swelling
than did the patients managed with an external fixator (p = 0.0146). At six to
eight weeks, the study patients had significantly less swelling of the
proximal phalanx (p = 0.0001) and middle phalanx (p = 0.0012) of all four
fingers, the proximal phalanx (p = 0.0319) and distal phalanx (p = 0.0061) of
the thumb, and the forearm (p = 0.0148). When all six measurements were
combined, the only significant difference was found at six to eight weeks,
with less measurable edema in the study patients than in the control patients
(p < 0.0001).
The results of the Jebsen dexterity test were analyzed on the basis of
dominance for the seven tasks tested. Significant differences were seen at the
six to eight-week period only. Of the patients who had injured the nondominant
hand, those in the study group took less time to write a short sentence (p =
0.028), turn cards (p = 0.0005), pick up small objects (p = 0.0008), and lift
heavy objects (p = 0.001) with the nondominant hand than did the control
patients. Of the patients who had injured the dominant hand, those in the
study group took less time to pick up small objects (p = 0.0023). No
significant differences were observed at later time-points. The effect of age
in all of the dexterity tests was significant and indicated that patients who
were sixty years of age and older took more time to finish these tasks.
Functional outcome, as measured with use of the modified clinical scoring
system of Green and
O'Brien27,28,
was the same for both groups at one year. The average score was 77 points for
the study group and 78 points for the control group. In the study group, the
result was excellent for 13% of the patients, good for 32%, fair for 40%, and
poor for 15%. In the control group, the result was excellent for 17% of the
patients, good for 28%, fair for 44%, and poor for 12%. There were no
significant differences between the two groups.
Radiographic Evaluation(Figs.
1-A,1-B,1-C,
1-D,1-E,
1-F)
At one week postoperatively, the SRS-treated fractures were in slightly
better position, compared with the uninjured wrist, than were the fractures in
the control group, with significant differences (p < 0.05) with respect to
loss of radial length (1.3 compared with 2.6 mm), loss of radial angle
(2.7° compared with 4.2°), radial shift (1.7 compared with 2.1 mm),
change in volar/dorsal angle (7.3° compared with 10.6°), and change in
ulnar variance (0.2 compared with 0.4 mm). The fractures in both groups tended
to settle with time, but more so in the study group such that, by six to eight
weeks, the groups were radiographically equivalent with the exception of the
change in ulnar variance, which was higher in the study group (2.2 compared
with 1.5 mm) (see Appendix). The results at twelve months were similar,
including loss of radial length (4.5 compared with 3.7 mm), loss of radial
angle (4.5° compared with 4.6°), radial shift (2.7 compared with 2.4
mm), change in volar/dorsal angle (10.3° compared with 10.5°), and
change in ulnar variance (2.0 compared with 1.4 mm). Only the change in ulnar
variance was significant (p = 0.02).
Covariate adjustment indicated that, for both groups, extra-articular
fractures were associated with greater loss of radial length, loss of radial
angle, change in volar/dorsal angle, and radial shift than were
intra-articular fractures (p < 0.05). The cast or external fixator
treatment designation also showed a significant difference. Within the control
group, the patients managed with a cast, compared with those managed with an
external fixator, had a greater loss of radial length (4.5 compared with 1.9
mm), loss of radial angle (6.0 compared with 1.9 mm), radial shift (2.1
compared with 1.9 mm), change in volar/dorsal angle (13.0° compared with
5.6°), and change in ulnar variance (1.5 compared with 1.1 mm).
Gender appeared to exert an independent effect only with respect to ulnar
variance: men had a larger change in mean ulnar variance (2.5 mm) than did
women (1.5 mm) (p = 0.0465). There were significantly more men in the study
group. When controlled for gender, the two treatment groups demonstrated no
significant difference with respect to ulnar variance. Neither hand dominance
nor the dual x-ray absorptiometry score appeared to have an independent effect
on the radiographic result.
With respect to articular step-off, no significant differences were noted
between the two groups. At the time of the three-month evaluation, eight of
the seventy-four intra-articular fractures treated with SRS had a detectable
step-off, with a mean value of 0.9 mm. None of the study patients had a
step-off of >2 mm. In the control group, eleven of the sixty-nine
intra-articular fractures had a detectable step-off, with a mean value of 1.1
mm. One of the control patients had a step-off of >2 mm.
As reported by the investigators, loss of reduction occurred in forty-six
(29%) of the study patients and in forty (25%) of the control patients; the
difference was not significant. Secondary treatment was performed in nine
(20%) of the forty-six study patients and seventeen (43%) of the forty control
patients following loss of reduction (p = 0.0209). Interventions included open
reduction with internal fixation, autogenous bone-grafting, osteotomy, or a
repeat closed reduction and cast application. These patients, who were
considered to have had failure of treatment, remained in the study for twelve
months.
Influence of Supplemental Kirschner Wires
In the control group, Kirschner wires were used in eighty-two patients
(51%). An average number of 2.2 wires (range, one to five wires) were in place
for a mean of fifty-one days. In the study group, supplemental Kirschner wires
were used in sixty-four patients (40%). An average of 1.5 Kirschner wires
(range, one to three wires) were in place for a mean of twenty-eight days. In
two patients, intraoperative removal of the Kirschner wires following
injection of the SRS resulted in fragmentation of the material and loss of
reduction.
For both groups, the presence of Kirschner wires had a significant impact
on maintenance of reduction. In the control group, loss of reduction occurred
in eleven (13%) of eighty-two patients who had Kirschner wires and in thirty
(38%) of eighty patients who had not had wires (p = 0.001). In the study
group, loss of reduction occurred in twelve (19%) of sixty-four patients who
had Kirschner wires and in thirty-four (35%) of ninety-seven patients who had
not had wires (p = 0.025).
Complications
There were no systemic complications specifically related to the use of
SRS. Seventy-four (46%) of the 161 study patients experienced complications
compared with eighty-two (51%) of the 162 control patients (p = 0.403) (see
Appendix). There were a total of 101 complications in the study group and 121
in the control group. There were no significant differences in the occurrence
of the specific events reported with the exception of infection, which
occurred in four (2.5%) of the SRS-treated patients and twenty-seven (16.7%)
of the control patients (p < 0.001). Within the SRS-treated group,
infection occurred exclusively in patients with supplemental Kirschner wires.
One of these patients had development of osteomyelitis, requiring removal of
the SRS cement, intravenous antibiotics, and application of an external
fixator. He had no persistent or recurrent osteomyelitis, and the final result
was considered satisfactory. In the control group, eighteen infections were
related to the external fixator and nine infections were related to the
Kirschner wire. No control patient had development of osteomyelitis.
Loss of reduction was by far the most common complication overall,
involving forty-six patients (29%) in the SRS group and forty patients (25%)
in the control group; the difference was not significant (p = 0.4). A total of
twenty-three patients (14%) in the study group experienced neuropathies
compared with thirty-two patients (20%) in the control group. In the study
group, carpal tunnel syndrome developed in four patients and in each one it
was associated with loss of reduction, with the onset of symptoms ranging from
two weeks to twelve months postoperatively. In the control group, carpal
tunnel syndrome developed in eight patients.
Tendinopathies (tendinitis, tendon adhesion, weakness, rupture, or
stenosing tenosynovitis) were reported in twelve study patients and eight
control patients. Tendon ruptures occurred in six patients in the study group
and in two patients in the control group; all ruptures involved the extensor
pollicis longus tendon. Each of the extensor pollicis longus tendon ruptures
in the study group occurred in patients with extraosseous cement dorsally; the
ruptures were identified an average of 161 days (range, thirty-six to 337
days) postoperatively. There was no apparent relationship between the volume
of extraosseous cement and tendon rupture. Both of the extensor pollicis
longus tendon ruptures in the control group occurred in patients managed with
a cast, and the ruptures were identified forty-two and 281 days
postoperatively.
SRS cement was observed radiographically within the radiocarpal and/or
radioulnar joint space in four of the 161 study patients. None of the four
patients had associated symptoms or clinical sequelae attributable to the
intra-articular cement. The amount of cement within the joint diminished over
time and was not associated with radiographic evidence of arthritis at the
time of the most recent follow-up at an average of forty-eight months
postoperatively (range, twenty-four to seventy-two months).
SRS cement was identified radiographically within the soft tissues in 112
(70%) of the 161 study patients. The location of the extraosseous cement was
dorsal in 101 patients, volar in seventy-one, ulnar in fifty-four, and radial
in forty-seven. The amount of cement diminished with time in all instances.
Complete resorption was observed in seventy (63%) of the 112 patients by six
months and in eighty-three patients (74%) by twelve months.
A separate analysis of the patients with extraosseous SRS cement
demonstrated greater loss of alignment radiographically than that seen in
either the study patients without extraosseous cement or in the control group.
Loss of reduction was noted in forty-one (37%) of the 112 patients with
extraosseous SRS compared with five (10%) of the forty-nine study patients
without extraosseous SRS and forty (25%) of the 162 control patients. In
addition, total complications were more common in patients with extraosseous
SRS cement. Sixty-three (56%) of the 112 study patients with extraosseous
cement experienced complications in contrast to eleven (22%) of the forty-nine
study patients without extraosseous cement and eighty-two (51%) of the 162
control patients.
This investigation is the largest prospective, randomized, controlled study
of distal radial fractures that has been reported to date, as far as we know.
The patient cohorts were identical demographically in nearly every parameter
including fracture type and severity. The size of the trial, the use of
standardized outcome instruments, and the length and completeness of follow-up
were intended to minimize problems noted in prior clinical studies.
While the importance of the final functional outcome following a distal
radial fracture is indisputable, the time to return to function perhaps has
been underappreciated. In a study of patients at least eight weeks following a
distal radial fracture, Beaule et
al.37 demonstrated
substantial impairment across a spectrum of activities, including personal
hygiene and domestic and social activities, particularly when the dominant
limb was affected. Undoubtedly, their results would have been even more
dramatic had the study examined earlier time-points. In a similar study,
Morris38 found that
older adults had substantially lower physical functioning during the period of
immobilization. In the current study, the SRS-treated patients had the wrist
immobilized for four to six weeks less than the control patients did. The
earlier improvement in function in the study patients is therefore not
surprising.
The pattern of recovery of wrist motion in this series parallels the
findings in other prospective studies of early motion following stable
fixation with either
internal39,40
or non-bridging external
fixation41,42.
The ultimate range of motion seems to be unaffected by early initiation of
motion.
Despite the early wrist motion, the SRS-treated fractures behaved
radiographically in a manner similar to those in the control group. Some
settling of most fractures occurred during healing. Ultimately, the study
patients lost slightly more length as measured by ulnar variance. The mean
difference between the groups of 0.6 mm does not appear to be clinically
significant. These radiographic results are equivalent to or better than those
reported in the literature for similar
fractures35,43-45.
In what we believe is the only other randomized study of SRS cement in the
treatment of acute distal radial fractures, Sanchez-Sotelo et
al.10 demonstrated
superior clinical and radiographic results in the SRS-treated group. However,
several important differences between the studies deserve emphasis. Patients
in their control group were treated with closed reduction and application of a
cast alone. It has been fairly well established that cast treatment alone is
often inadequate for unstable distal radial
fractures46,47.
The relatively poor results in their control group (a 41.8% rate of malunion)
substantiate this observation. In contrast, the present study attempted to
reflect the current standard of care in the control group by including
treatment with a cast, external fixation, and percutaneous pin fixation.
Overall, the radiographic results in our control group were superior,
minimizing differences between the control and study groups. Furthermore, in
their series, the final radiographic result was compared with the immediate
postreduction radiographs. Our radiographic results were measured relative to
the normal wrist, thereby eliminating the variable of the quality of the
initial reduction. This method, however, probably magnified the values of our
radiographic changes.
A potential source of bias in the study was the treatment designation of a
cast or external fixator. Surgeon preference, including factors related to the
patient and the fracture, was considered in assigning a treatment designation
of a cast or external fixator to a particular fracture. Nevertheless, there
were no significant differences in fracture classification and severity
between the groups or subgroups.
Failure to include carpal malalignment in the data analysis may be
considered another potential weakness of this study. Bickerstaff and
Bell48 demonstrated
a strong correlation between function and dorsal carpal instability. Analysis
of our clinical results demonstrated that dorsal angulation was associated
with a reduction of grip strength. However, intercarpal angles were not
routinely measured on follow-up radiographs.
The use of percutaneous pins was another confounding factor. While the
presence of Kirschner wires did not influence the overall outcome of the study
and control groups, the rate of loss of reduction was significantly higher
within each group when Kirschner wires were not used. An in vitro
biomechanical comparison of Kirschner wire and SRS fixation of intra-articular
distal radial fractures has demonstrated the superiority of SRS cement in
resisting compressive
loads49. In vivo,
however, these fractures are also subjected to tensile and shear forces, which
are poorly controlled by the cement. It is not yet clear which fracture
patterns can safely be managed with SRS cement alone.
The nearly 50% complication rate for both groups in this series is
substantially higher than the 20% to 31% complication rate reported in several
large retrospective
studies12,29,50.
The prospective nature of the current study and the rigorous reporting at each
follow-up visit of any deviations from normal recovery permitted a
comprehensive account of complications. This method of reporting is likely
more accurate than a retrospective review. Some minor events, such as
stenosing tenosynovitis, have not been included routinely in other series and
may not generally be considered complications related to fracture
treatment.
In what we believe is the largest series to date on complications related
to distal radial fractures, Cooney et
al.50 considered
loss of reduction (which occurred in 27% of the patients) a complication only
if it went on to a malunion (5.3%) requiring subsequent treatment. In the
current study, loss of reduction was defined by the investigators a priori
with use of generally accepted radiographic criteria predictive of poor
outcome17,33,36,43,51-54.
The majority of the patients who lost reduction radiographically did well
clinically. Excluding the complications related only to radiographic findings,
the overall complication rate for both groups would be approximately 22%,
which is consistent with that in previous studies.
The loss-of-reduction issue highlights two important points. First,
radiographic signs of loss of position were not uncommon in the control group,
despite treatment by established and experienced surgeons with use of standard
techniques. Second, with few exceptions, the clinical outcome of the patients
in both groups was independent of the radiographic outcome.
The risk of extrusion of the SRS cement into undesirable locations has been
a substantial concern. In the series described by Sanchez-Sotelo et
al.10, one patient
had symptomatic intra-articular cement necessitating surgical removal. Of the
seventy-five intra-articular fractures treated with SRS in our series, four
had intra-articular extrusion. In each instance, the patient was asymptomatic,
and the amount of intra-articular cement diminished with time. No arthritic
changes were evident in any of the four wrists at twenty-four months, although
clearly a longer follow-up period is necessary.
The infrequent presence of intra-articular SRS appears to be related to a
combination of an adequate fracture reduction and the thixotropic properties
of the material, which is of a toothpaste consistency and does not flow
readily into narrow channels. Nevertheless, we currently recommend careful
inspection of the postinjection radiographs and evacuation of any
intra-articular cement identified intraoperatively.
The presence of extraosseous cement, seen in the majority of patients, was
associated with a higher complication rate. Delivery of the SRS cement through
a mini-open approach facilitated removal of excess dorsal material. Volar
extrusion, although quite common, was not associated with any unique
complications, and we did not remove it. Dorsal extrusion of cement can
interfere with extensor tendon function. In our series, tendon ruptures
exclusively involved the extensor pollicis longus tendon in both groups. This
finding is consistent with those in other reports of tendon ruptures in
association with distal radial
fractures12,51,55-59.
Extraosseous SRS was identified dorsally in each study patient who sustained a
tendon rupture; this finding is of some concern. However, the prevalence of
extensor pollicis longus tendon ruptures in the SRS group was not
significantly different from that in the control group or the historical
prevalence of 1% to 5%. Longer follow-up of our study patients is required to
determine the possible adverse effects of extraosseous extrusion of the
cement.
Our data suggest that Norian SRS cement provides adequate fixation for the
majority of distal radial fractures to permit early wrist mobilization. It is
possible that the radiographic results would have been better with a longer
period of postoperative immobilization. However, for the majority of patients,
the earlier return of function following cement fixation appeared to outweigh
the slightly inferior radiographic result. On the basis of our current
understanding of this form of fixation, we make the following recommendations.
A limited open approach for fracture site preparation should be used.
Supplemental Kirschner wires should be placed prior to cement injection and
should be left in place for a minimum of two weeks postoperatively. Whenever
possible, extraosseous and intra-articular cement should be removed. The wrist
should be immobilized for two weeks and protected for an additional four
weeks. Complex articular fractures require additional fixation or another form
of treatment.
Note: The authors thank the following investigators who
contributed patients to this multicenter study: Jeffrey Angel, MD, J. Dean
Cole, MD, Robert M. Dalsey, MD, Jerome Davis, MD, Vincent G. Fietti, MD, John
Hermansdorfer, MD, Thomas Hunt, MD, Samuel C. Kline, MD, Harry J. Molligan,
MD, Stephen J. Leibovic, MD, Joseph A. Longo, MD, Margaret McQueen, MD,
Clifford Posman, MD, Michael Rothberg, MD, Leonard K. Ruby, MD, Thomas F.
Varecka, MD, A.D. Verberg, MD, and Douglas Wright, MD.