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TRAUMA SURGERY
Early results in the treatment of proximal humeral fractures
with a polyaxial locking plate
Johannes B. Erhardt ÆG. Roderer ÆK. Grob Æ
T. N. Forster ÆK. Stoffel ÆM. S. Kuster
Received: 14 January 2008
ÓSpringer-Verlag 2009
Abstract
Objectives We report early results using a second gen-
eration locking plate, non-contact bridging plate (NCB
PH
Ò
, Zimmer Inc. Warsaw, IN, USA), for the treatment of
proximal humeral fractures. The NCB PH
Ò
combines
conventional plating technique with polyaxial screw
placement and angular stability.
Design Prospective case series.
Setting A single level-1 trauma center.
Patients A total of 50 patients with proximal humeral
fractures were treated from May 2004 to December 2005.
Intervention Surgery was performed in open technique in
all cases.
Main outcome measures Implant-related complications,
clinical parameters (duration of surgery, range of motion,
Constant–Murley Score, subjective patient satisfaction,
complications) and radiographic evaluation [union, implant
loosening, implant-related complications and avascular
necrosis (AVN) of the humeral head] at 6, 12 and
24 weeks.
Results All fractures available to follow-up (48 of 50)
went to union within the follow-up period of 6 months.
One patient was lost to follow-up, one patient died of a
cause unrelated to the trauma, four patients developed
AVN with cutout, one patient had implant loosening, three
patients experienced cutout and one patient had an axillary
nerve lesion (onset unknown). The average age- and gen-
der-related Constant Score (n=35) was 76.
Conclusions The NCB PH
Ò
combines conventional
plating technique with polyaxial screw placement and
angular stability. Although the complication rate was 19%,
with a reoperation rate of 12%, the early results show that
the NCB PH
Ò
is a safe implant for the treatment of prox-
imal humeral fractures.
Keywords NCB Proximal humerus Fracture
Non-contact bridging Polyaxial locked plate
Introduction
Proximal humeral fractures are the third most common
fracture after hip and distal radius [19]. Palvanen et al. [19]
showed that the incidence and number of these fractures
has tripled within the last three decades in Finland and if
this trend continues the same can be expected for the
future. In particular, a high risk of humeral fracture results
from the combination of osteoporosis with an increased
risk of falling [16]. The management of proximal humeral
fractures has undergone transformation in the recent past
due to the emergence of innovative treatment techniques.
With the invention of locked plating, a novel biomechan-
ical approach has become available for the stabilization of
these fractures [5,7,24]. The blood supply to the humeral
head [8] prohibits medial positioning of a plate, therefore,
early loss of fixation is a commonly reported problem in
comminuted and osteoporotic fractures especially [1,13,
18]. The lateral placement of a locked implant means that
J. B. Erhardt (&)K. Grob T. N. Forster M. S. Kuster
Klinik fu
¨r Orthopa
¨dische Chirurgie, Kantonsspital St. Gallen,
9007 St. Gallen, Switzerland
e-mail: johannes.erhardt@kssg.ch
J. B. Erhardt K. Stoffel M. S. Kuster
Fremantle Orthopaedic Unit,
The University of Western Australia,
Perth, WA, Australia
G. Roderer
Abteilung fu
¨r Unfallchirurgie, Universita
¨tsklinik Ulm,
Ulm, Germany
123
Arch Orthop Trauma Surg
DOI 10.1007/s00402-009-0924-7
reduction is maintained by screws that act as struts [9].
Therefore, the indication for osteosynthesis, even for dis-
placed three and four part fractures, has increased in rela-
tion to hemiarthroplasty [11,25].
Early results for these locked plates have been published
over the last 5 years [2,11,15,20,22,23]. The most
commonly used implant reported was the Philos
Ò
plate
(Synthes). The clinical outcomes of various studies
involving this implant have been published and they all
conclude that it is suitable for use in the treatment of
comminuted fractures of the proximal humerus in osteo-
porotic bone. However, all of them also report a significant
number of complications due to screw perforation through
the humeral head and, therefore, variable re-operation
rates. Different potential solutions have been proposed
such as screw augmentation with calcium phosphate
cement in combination with both locked and conventional
plates [9,22], limited drilling in osteoporotic bone, the use
of blunt-tipped locking screws[21], and locking plates with
polyaxial screws like the non-contact bridging plate (NCB,
Zimmer)[23]. The NCB combines the properties of con-
ventional and locking plates. In this article, early results
and implant-related complications are presented for use of
the polyaxial non-contact locking (NCB
Ò
) plate, a second
generation locking device.
Materials and methods
After approval from the ethics committee had been granted,
the first 50 patients to be treated with the NCB
Ò
PH for an
acute traumatic fracture were prospectively enrolled in the
study starting in May 2004. Endpoints of the study were the
clinical and radiological outcomes and complications after
6 months. Clinical parameters included range of motion
(ROM) in flexion and abduction, and the subjective success
of the outcome was based on a high, intermediate or poor
level of patient satisfaction. Radiological parameters
included union/non-union, implant loosening, screw perfo-
ration and avascular necrosis (AVN). Exclusion criteria
were pathological fractures (caused by neoplasia), hardware
failure of other implants whereby the NCB
Ò
PH was a
revision procedure, preoperative axillary nerve damage and
inadequate follow-up. Adequate follow-up was considered
Fig. 1 Surgical technique of
indirect fracture reduction using
the plate as a buttress. Image
intensifier images and
postoperative X-rays
Arch Orthop Trauma Surg
123
adequate if the patients had documented clinical and
radiological healing or had attended all the scheduled fol-
low-up appointments. The follow-up appointments were 6,
12 and 26 weeks after the surgical procedure. The Constant–
Murley score was not included in the initial follow-up pro-
tocol. Therefore, after completing the 26-week follow-up,
each patient returned again so that their Constant–Murley
scores could be obtained [4]. The indications for surgical
treatment were all displaced three and four part fractures,
type A fractures with varus malalignment and medial com-
minution, or fractures with almost 100% displacement (type
A2 and A3 according to the AO ASIF classification).
Implant and locking mechanism
The plate is a newly designed second generation locked
implant, combining the properties of conventional plates
with the special features of locked plates. It is available in
two versions: a 4- and a 5-hole plate. The plate is suitable
for both the left and right sides. It comes with a radiolucent
targeting device so that the plate can also be inserted in
minimally invasive technique as reported by Roderer et al.
[23]. The plate can be used with solid or cannulated screws
and 4.0 mm cortical and 4.5 mm cancellous screws. This
way tactile feedback on the quality of the bone is still
given, in contrast to other locking mechanisms. Second-
arily, the screws can be locked with the NCB locking screw
with a torque of 4 Nm and up to an angle of a total of 30°.
This, in contrast to other locking mechanisms, provides no
absolute angular stability. In the study presented here
failure of the locking mechanism was not reported in
contrast to published data of failure of an absolute angular
stable implant [2,9]. The plate has oblique 2 mm holes for
the reattachment of the rotator cuff.
Surgical technique
The method of choice was open reduction through a delto-
pectoral approach in all patients. As proposed by Hertel
[12], the reduction of the fracture was performed indirectly
without dissecting the single fractured parts whenever
possible. Initially all three rotator cuff tendons were held
with non-resorbable sutures. In the majority of cases, good
reduction can be achieved by applying axial traction on the
humerus and pulling the rotator cuff, e.g. the greater and
lesser tubercles in an anterior-inferior direction, supple-
mented by use of the NCB
Ò
as an indirect reduction tool
and insertion of compression screws as illustrated in Fig. 1.
After reduction, the head screws were placed polyaxially
and as divergently as possible and then locked. This was
essential in cases of medial comminution. Finally, the
sutures were fixed through the 2 mm oblique holes in the
plate.
Postoperative regimen
In this series, all patients underwent an early passive
mobilization regimen. All patients were treated with a
restraining shoulder bandage for at least 4 weeks. In the
first 2 weeks, single pendulum exercises with passive
mobilization up to 30°were allowed with an increased
range of 90°in the third week. In the fourth week, active
mobilization without weight was performed and, finally, in
the sixth week full active mobilization was allowed.
Outcome parameters
Data were collected with regard to demographics, operative
details, and the duration of inpatient stay. Clinical and
radiological follow-up took place at 6, 12 and 26 weeks. The
patients were assessed at the 6-, 12- and 26-week follow-ups
radiologically and clinically (total shoulder movement in
flexion and abduction, subjective success of the outcome with
a high, moderate or poor level of satisfaction). Radiographic
evaluation included union, implant loosening, hardware-
related complications and AVN of the humeral head. Union
was defined in terms of the patient reporting no shoulder pain
or only mild activity-related pain and having no loss of initial
fracture reduction or evidence of implant loosening, break-
age, combined with evidence of internal or external callus
formation [22]. The Constant–Murley score was not included
in the initial follow-up protocol. Therefore, after the patients
had completed the 26-week follow-up, they were all invited
back so that a Constant–Murley score could be obtained [4].
For analysis of change of ROM from 6 to 26 weeks, an
independent samples ttest was performed using the
Table 1 The demographics of patients and fractures
Mean age in years (range) 61 (25–91)
Sex 20 Males 30 Females
Affected side 20 Right 30 Left
Fracture classification
AO/ASIF
Type A 11
Type B 21
Type C 19
Average length of surgery
in min (±SD)
76 ±29
Average length of
hospital stay in days
(±SD)
7±4
Mean follow-up in
months (range)
10 (3–22)
Injury mechanism
Body height fall 39
Road traffic accident 2 Bicycles, 4
motorbikes, 3 cars
Sport 2 While skiing
Arch Orthop Trauma Surg
123
software SSPS 15.0 for Windows with a significance
threshold of p\0.05.
Results
Clinical and radiological follow-up was possible for 48 of
50 patients. One patient failed to attend any of the follow-
up appointments and the second patient died of a cause
unrelated to the trauma. The fractures united in all 48
patients available for clinical and radiological follow-up.
The shortest follow-up period was 3 months; this patient
was content with documented clinical and radiological
healing and did not want to attend any further appoint-
ments. The demographics of the patients and the fractures
are shown in Table 1.
No adverse events were reported with regard to the
surgical procedure. The adjacent joints were mobilized
during the inpatient stay whereby, in this case series, early
mobilization of the shoulder was performed in a very
conservative way with just swinging the arm for 2 weeks
and then starting passive mobilization to 90°. The results
for average flexion and abduction (with free scapula) are
shown in Fig. 2.
After completion of the initial follow-up protocol all
patients were invited for Constant–Murley scoring [4] after
a minimum of 6 months, postoperatively. Thirty-five
patients attended this appointment. The average follow-up
period at this stage was 10 months. The average age of
these patients was 70 (47–91) years. According to the study
of Katolik [14] an age- and gender-related Constant Score
was calculated using the formula: (raw score/normal
score) 9100. We used the normal scores as presented in
the series of Katolik [3,14], which are higher values than
those Constant described initially. Therefore, the risk of
overestimating shoulder function is decreased. The results
Mean Range of Motion
0
20
40
60
80
100
120
140
160
180
200
Degrees
Flexion
Flexion
Flexion
Abduction
Abduction
Abduction
6 weeks 3 months 6 months
Fig. 2 Functional results of
flexion and abduction at
6 weeks, 3 months and
6 months after the surgical
intervention. The increase in the
range of motion between each
follow-up was significant
(p\0.05)
0
10
20
30
40
50
60
70
80
90
100
Raw Constant
Score,
Total (max.100)
Pain
(max.15)
ADL
(max.20)
ROM
(max.40)
Force
(max.25)
Fig. 3 Results of the Raw–
Constant–Murley Score (±SD)
after an average follow-up
period of 10 months. The
average score was 66 ±16 in
n=35 patients. The table
shows the four sections of the
score including pain, activities
of daily life (ADL), range of
motion (ROM), and strength
Arch Orthop Trauma Surg
123
showing an average raw score of 66 ±16 are presented in
Fig. 3. Patient data and the calculated age- and gender-
related Constant Score of 76 ±18 are given in Table 2.
In addition, the subjective level of satisfaction was
evaluated and recorded in three stages. Thirty-eight
patients showed high satisfaction at the final follow-up,
eight patients were moderately satisfied, and two patients
were dissatisfied with the treatment outcome. Implants
were removed from four patients because of an impinge-
ment syndrome.
Complications
During the follow-up period the complication rate was
18.7% (9 of 48 cases). Partial axillary nerve palsy was
reported in one case (2%). The patient with a history of
cervical fusion could not remember whether the palsy was
already present before the surgical intervention, but
because it was not clearly reported in the medical and
emergency department chart, we assumed it to be a com-
plication. In three patients (6.2%), cutout of at least one
screw through the humeral head into the joint was noted
within the first 6 weeks so that either removal of some
implants or replacement of at least one screw was required
(Fig. 4). With reference to the AO ASIF classification,
these complications occurred in 2 type C fractures and 1
type A fracture with 100% displacement. In four patients
(8.3%) partial AVN developed, which led in all cases to
screw perforation of the humeral head, requiring partial or
complete implant removal in three patients. The AO ASIF
classifications in these cases were 2 type C, 1 type B and 1
type A with 100% displacement. Implantation of a pros-
thesis was not necessary in any of these cases. Finally, in
one (2%) 91-year-old demented non-compliant patient, the
plate loosened during the inpatient stay leading to loss of
reduction of the humeral head. In the further course this
was managed non-surgically. In summary, the complica-
tion rate was 18.7% (9 of 48 cases) with a re-operation rate
of 12.5% during the follow-up period (Table 3).
Discussion
The treatment modalities for proximal humeral fractures
have increased since the introduction of fixed angled
devices. The introduction of these devices has encouraged
surgeons to decide in favor of surgical treatment, in gen-
eral, and osteosynthesis rather than a prosthesis, in partic-
ular [25]. However, non-surgical management of these
fractures still dominates in the majority of cases [10,25].
Because of the increasing incidence of this type of injury
[19] and the increasing demands on shoulder function at an
older age, the number of patients receiving surgical treat-
ment will increase in the future.
This article is based on the first 50 cases prospectively
enrolled and treated at our institution since the introduction
of the NCB
Ò
humeral plate in 2004.
Early clinical results show good clinical outcome with
variable complication rates [2,6,11,15,20,22,23]for
the locked plates. However, these authors all report a
significant number of complications due to screw per-
foration through the humeral head. A complication
occurring more commonly since the introduction of
locked implants is the cutout of screws through the
Table 2 Patient data including age, gender, raw Constant score and
age- and gender-related Constant Score
Patient Age Gender Raw Constant
Score
Age/gender-related
Constant Score
1 47 M 93 97
2 79 F 65 80
3 84 F 75 93
4 59 M 86 91
5 59 F 69 82
6 74 F 74 91
7 47 M 60 63
8 77 F 41 51
9 64 M 81 88
10 75 M 74 91
11 57 F 38 45
12 68 F 60 72
13 72 F 81 100
14 58 M 70 74
15 58 M 89 95
16 65 M 84 91
17 64 M 45 49
18 48 F 67 78
19 72 F 80 99
20 75 F 80 99
21 68 M 45 49
22 75 F 52 64
23 49 M 74 77
24 61 M 88 96
25 75 M 73 83
26 83 F 53 65
27 63 F 78 94
28 81 F 57 70
29 76 F 52 64
30 88 F 35 43
31 86 F 57 70
32 90 F 45 56
33 91 F 66 81
34 90 F 40 49
35 57 F 66 79
Arch Orthop Trauma Surg
123
calvarium because of the inability to fix the head frag-
ment in position until fracture healing is completed. This
risk seems to be especially great if the medial hinge is
not restored by reduction or, alternatively, by insertion of
an inferior-medial locking screw [9]. Charalambous et al.
[2] report a series of 25 cases treated with the Philos
Ò
plate. They present 17 acute cases and 8 cases treated
after delayed or non-union, or previous hardware failure.
They reported 15 complications in the acute group and 5
in the other group. In total, 20% of the cases needed
surgical revision. In the largest case series to date,
Kettler et al. [15] reported an overall complication rate
of 37% (65 of 176) with primary or secondary ‘‘cut out’’
phenomena or implant loosening in 26% (46 of 176) in a
case series of 225 (176 available to follow-up) with a re-
operation rate of 16.4%. At the end of the study, 47
plates had been removed. Furthermore, several authors
have reported plate breakage, failure of the locking
mechanism, and backing up of locked screws [2,6,15]
for the Philos plate. For the NCB
Ò
PH Roderer et al.
[23] reported a slightly decreased rate of complications
at around 23% in a case series of 61 patients using a
minimally invasive technique, with a re-operation rate of
17%, not including the plate removals (3 patients) due to
impingement. These results are similar to those we
present for the NCB
Ò
using a delto-pectoral approach
and open reduction technique with a complication rate of
18.7% and a re-operation rate of 12.5%.
Fig. 4 These radiographs show the radiological course of an AO
ASIF 11 C2 fracture in a 47-year-old male. At the 6-week follow-up,
cutout of one screw was visible in the glenohumeral joint and
conversion to a shorter screw was performed. Ten months after the
injury the Constant score was 60
Table 3 Complications seen in 18.7% (9 of 48) patients treated with
the NCB PH for an acute proximal humeral fracture
Partial axillary nerve palsy 1 (2%)
Cutout of screw in the
glenohumeral joint
without AVN
3 (6.2%) AO/ASIF
2 Type C, 1 Type A
Cutout of screw in the
glenohumeral joint with
partial AVN
4 (8.3%) AO/ASIF
2 Type C, 1 Type B,
1 Type A
Loosening of implant and
loss of fixation
1 (2%) 1 AO/ASIF Type C
Arch Orthop Trauma Surg
123
Including our own patients treated with the NCB
Ò
,no
plate breakage or failure of the locking mechanism has
been reported to date. This might be because the NCB Plate
is slightly thicker than other plates and the locking mech-
anism with locking cap offers more resistance to backing
out of screws. Whether the absence of reported screw
breakages is thanks to the thicker screw diameter of
4.5 mm compared to other implants or to the design of the
locking mechanism is not absolutely clear. It is also not
clear whether this relative angular stability plays a bene-
ficial role in reducing the rate of screw perforations into the
joint. Another feature which might have an influence on the
rate of screw perforations into the joint is the thicker screw
diameter and the option of using cancellous screws.
The specific advantages of polyaxiality in combination
with the locking mechanism are that during drilling and
screw insertion the feel for bone quality is preserved
and the screw can be directed into an area of good bone and
then locked afterwards. Polyaxiality also facilitates the
positioning of an infero-medial screw as described by
Gardner [9].
Even if biomechanical data is confirming the benefits of
elastic properties in the fixation stability of locked plates
compared to nails and conventional plates [17], no rec-
ommendations have yet been validated by biomechanical
data on how to position the screws in the humeral head to
achieve maximal fixation stability, especially with poly-
axial second generation locking plates.
A limitation of this study is that this case series only
yields preliminary results with an endpoint of the study
after 6 months. Even though the clinical and radiological
follow-up rate was 96% a Constant–Murley score was only
obtained for 72% of the patients. However, without
exception all fractures united during the follow-up period
in the patients available to follow-up (48 of 50) and, in our
experience, implant-related complications generally occur
in the early postoperative period. It is not possible to
comment on the later development of total or partial AVN,
whereby the rate of 8.3% recorded for our series is much
lower than the rate of 16% obtained by Hente et al. [11]in
their series for a similar distribution of fracture patterns.
This might be related to the short follow-up period.
Another limitation of this study is the lack of a comparative
group. On the basis of the prospective follow-up of the first
50 cases, it is certainly a reliable documentation of the
treatment outcomes that can be achieved in a cohort
comprised of 83% AO ASIF type B or C proximal humeral
fractures when these are managed by application of a
second generation locking device. This report also provides
an almost complete picture of this prospective case series
since the ‘‘fate’’ of only one implant is unknown.
As various authors state, no prospective clinical trials
have been conducted to date to compare locked implants
with polyaxial locked implants or even conventional plates
or non-surgical treatment [10]. The treatment of proximal
humeral fractures remains a challenge despite the expan-
sion of treatment options since the introduction of locked
plates. There is still great potential to improve the out-
comes, especially in terms of decreasing the rates of fixa-
tion failure and cutout.
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