22
Malaysian Orthopaedic Journal 2016 Vol 10 No 1 Raval P, et al
ABSTRACT
Introduction: A comparative evaluation of the surgical
treatment and outcome of patients with pertrochanteric
fractures treated with short versus long proximal femoral nail
antirotation.
Materials and methods: A retrospective review was
conducted of patients with pertrochanteric fractures treated
between January 2011 and June 2012. In all 80 patients were
enrolled in the study, of which 40 were treated with short
PFNA and the remaining with long PFNA. Comparative
analyses of demographic data, peri-operative outcome and
complications were carried out.
Results: There was no significant difference noted in the two
groups with regards to Arbeitsgemeinschaft fur
Osteosynthesefragen (AO) fracture classification, time from
injury to surgery, blood transfusion post surgery and hospital
stay. The surgical duration for a short PFNA procedure was
significantly less (58 minutes) when compared to that of a
long PFNA (87 minutes). Similarly intra-operative blood
loss was significantly higher in the long PFNA group as
compared to the short PFNA.
Conclusions: A relatively quicker surgical time of just under
an hour , lesser blood loss and better learning curve with
trainee surgeons make short PFNA a better implant choice in
the treatment of pertrochanteric fractures.
Key Words:
Pertrochanteric fractures, Proximal Femoral Nail
Antirotation, Short, Long, Intramedullary fixation
INTRODUCTION
The advancement in modern medicine has enabled many to
live long. However, as the age advances so do certain co-
morbidities. Osteoporosis is one such significant co-
morbidity. The increased prevalence of hip fractures in
osteoporotic individuals is well known
1,2
. Trivial trauma such
as a fall from a standing height is the most common cause for
sustaining a fragility fracture
3
. The number of hip fractures
has been estimated to rise over the next few years, leading to
increasing costs and subsequent rising financial burden
4
.
Pertrochanteric fractures are those which are around the
trochanteric region of femur. They are classified as 31-A1
pertrochanteric simple, 31-A2 pertrochanteric
multifragmentary and 31-A3 intertrochanteric as per the
Arbeitsgemeinschaft fur Osteosynthesefragen (AO)
classification
5
.
There has been considerable debate over the method of
treating pertrochanteric fractures. Meta analytical studies in
literature have not been able to come to a consensus whether
an extramedullary or an intramedullary implant is better in
this regard
6-8
.
In our institution pertrochanteric fractures are treated by
using intramedullary devices, such as the AO-Proximal
Femoral Nail Antirotation (AO PFN-A). The PFN-A is
available in various sizes. The short version has 170mm,
200mm, 240mm as length and the long version if from 300-
420mm with 20mm increments and a bending radius of
1500mm
9
. Both the short and the long PFN-A implants are
routinely employed in the surgical treatment of
pertrochanteric fractures at our hospital.
The purpose of this retrospective study is to do a
comparative evaluation of the surgical outcome of patients
with pertrochanteric fractures treated using either a short or
a long PFN-A.
MATERIALS AND METHODS
Retrospective data was collected from the operation theatre
implant book regarding the type of PFN-A used. Using that
data the relevant patient charts were retrieved from the
medical records. A total of 117 patients underwent surgery
for pertrochanteric fracture using PFN-A, between January
Comparison of Short vs Long Anti-rotation in Treating
Trochanteric Fractures
Raval P, MCh Orth, Ramasamy A, MRCSEd, Raza H, MRCSI, FEBOT, Khan K, FRCS Orth,
A
wan N, FRCS Orth
Department of Orthopaedics, Wishaw General Hospital, Scotland, United Kingdom
D
ate of submission: December 2015
Date of acceptance: March 2016
Corresponding Author: Pradyumna Raval, Department of Orthopaedics, Wishaw General Hospital, Scotland United Kingdom
Email: raval.prashant@gmail.com
h
ttp://dx.doi.org/10.5704/MOJ.1603.005
5-B217_OA1 6/11/16 2:56 PM Page 22
Short vs Long PFNA comparison
23
2011 and June 2012. However only 80 patients met the
inclusion criteria for the study (Table I). Patients with
multiple injuries and pathological fractures were excluded
f
rom the study.
The surgery was performed as soon as the clinical condition
of the patient permitted (Table II). All patients were started
on mechanical and chemical methods of deep venous
thrombosis (DVT) prophylaxis on admission, as per the
h
ospital guidelines. Antibiotics belonging to the beta-lactam
group were administered 30 minutes prior to incision and
two doses were repeated post surgery. In cases of penicillin
allergy, macrolide or quinolone group of antibiotics were
used. Spinal anaesthesia was administered in majority of the
cases (Table III).
Our institution is a major teaching hospital and most
surgeries in this particular study were performed by the
Consultant Orthopaedic surgeon, while some were
performed by senior trainee residents under direct
supervision of the consultant. Surgeries were performed on a
traction table under the guidance of an image intensifier.
Longitudinal traction was applied to achieve reduction and
realignment of the fracture fragments. Open reduction was
resorted to when the closed manoeuvre failed. Distal locking
was performed using the aiming device for the short PFN-A,
whereas a free hand technique was employed for the long
PFN-A. Reaming was performed in all cases. The standard
operating manual as supplied by the manufacturer was
followed during the procedure
9
.
Intraoperatively, the duration of surgery, method of fracture
reduction (closed versus open) and blood loss were recorded
(Table III). Postoperative radiographs were taken to ascertain
the fracture reduction and position of the implant. Patients
were started on active and passive movements immediately
and partial or full weight bearing was allowed as soon as the
patient’s general condition and any pre-existing co-
morbidity allowed. Subcutaneous DVT prophylaxis was
continued till the patient was satisfactorily mobile. Any
blood transfusions and total days of hospitalisation were
noted (Table IV). Patients were discharged on oral anti-
coagulants.
All patients were monitored at 1, 3, 6 and 12 months after the
surgery. Radiographs were taken at each follow up and
compared against the previous images. At each visit, status
of fracture union was noted. All patients had radiological
union evident by the 12th month of follow up. Improvement
in mobility of patients was noted during each visit.
All implants used in the short PFN-A group had a length of
240mm but different diameters. (Figure 1). However
implants of varying lengths were used in the long PFNA
group (Figure 2).
Statistical analyses were conducted using Analysis ToolPak
on Microsoft Excel 2010 (v14.0). Continuous normally
distributed data were analysed using a two sample Student’s
t
test and Pearson’s chi-square test was used to compare
groups with categorical variables. A probability (p value) of
< 0.05 was considered to be statistically significant.
RESULTS
80 patients underwent surgery for pertrochanteric fractures
in the period from January 2011 and June 2012. There were
40 patients each in the short and long PFNA groups. The
patient characteristics of both groups was not significantly
different (Table II)
Both groups had a higher number of female patients with an
average of around 70 %. The mean age for the short PFNA
group was 77 years (range: 68-86 years) and 76 years
(range: 68-84 years) for the long PFNA group. There were
identical numbers of 31-A1 fractures in both groups and this
was also the most common fracture type in either. Most
patients in both groups were operated upon within three days
of sustaining the injury.
There was no significant difference in the type of anaesthesia
administered to the patients in either groups (p = 0.445).
Spinal anaesthesia however, was most commonly
administered. 70 % of the short PFNA patients and 77 % of
the long group got spinal anaesthesia.
30 % of the short PFNA surgeries were performed by trainee
residents as compared to only 10 % of the long PFN-A ones
(p = 0.025). These were performed under direct supervision
of the Consultant Orthopaedic surgeon. Most procedures
were performed closed, however one open reduction was
performed in the short PFN-A group and four were
performed in the other group.
The amount of blood loss was greater in the long PFN-A
group (341ml vs. 172ml, p = 0.042). The operative procedure
lasted for 58 minutes (range: 46-70 minutes) in the short
PFN-A group as compared to 87 minutes (range: 55-119
minutes) in the long PFN-A group (p = 0.016) (Table III).
There was no significant difference in the postoperative
outcome of both the groups and the data was comparable
(Table IV). Twice the number of patients (eight vs four) got
blood transfusions in the long PFN-A group as compared to
the other. The mean hospital stay for both groups was similar
at approximately 11 days. None of the patients of either
group had any infection while they were in the hospital. All
patients were discharged once they had independent mobility
and their assigned physical therapists were satisfied with
their progress.
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Malaysian Orthopaedic Journal 2016 Vol 10 No 1 Raval P, et al
24
Table I: Patient selection criteria
Inclusion Criteria Exclusion Criteria
• Patients with age > 60 years • Polytrauma patients
• Pertrochanteric fracture sustained after trivial trauma • Patients with pathological fractures
• Patients with concomitant sub-trochanteric or
shaft femur fractures
Table II: Pre-operative Data (Demographics, Fracture type, Time to surgery)
Variable Total Short PFN-A Long PFN-A ‘p’ value
Number 80 40 40 --
Gender
Male/Female 23/57 11/29 13/27 0.625
$
Age(years)
Mean +/- SD 75.9 +/- 9.1 77.1 +/- 9.2 76.1 +/- 8.7 0.806
£
AO fracture type
31-A1/A2/A3 21 / 48 / 11 12 / 24 / 4 9 / 24 / 7 0.536
$
Time between injury and surgery (days)
Mean +/- SD 2.3 +/- 1.9 2.2 +/- 2.2 2.5 +/- 1.7 0.744
£
$
Chi-square test
£
Two sample t-test
Table III: Intra-operative Data (Anaesthesia, Duration, Blood loss, Operating surgeon)
Variable Total Short PFN-A Long PFN-A ‘p’ value
Number 80 40 40 --
Anaesthesia
(General/Spinal) 21 / 59 12 / 28 9 / 31 0.445
$
Duration of surgery (minutes)
Mean +/- SD 72.3 +/- 28.0 58.6 +/- 12.6 87.7 +/- 32.6 0.016
£
Open reduction of fracture (n) ---- 14----
Intra-operative blood loss (ml)
Mean +/- SD 253.1 +/- 190.6 172.7 +/- 156.9 341.7 +/- 191.8 0.042
£
Operating Surgeon
Consultant / Registrar under supervision 64 / 16 28 / 12 36 / 4 0.025
$
$
Chi-square test
£
Two sample t-test
Table IV: Post-operative Data (Transfusion, Hospital stay, Reoperations, Mortality)
Variable Total Short PFN-A Long PFN-A ‘p’ value
Number 80 40 40 --
Blood transfusion (n) 12 / 80 4 / 40 8 / 40 0.210
$
Hospital stay (days) 11 +/- 5.4 11.1 +/- 6.2 10.9 +/- 4.8 0.937
£
Reoperations(n) 3 / 80 1 / 40 2 / 40 0.556
$
Mortality (n) 8 / 80 3 / 40 5 / 40 0.456
$
$
Chi-square test
£
Two sample t-test
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Short vs Long PFNA comparison
25
Three patients had reoperations. Two from the long PFN-A
group and one from the short. There was a screw cut-out in
the short PFN-A patient, which was subsequently revised to
a hemiarthroplasty. Of the other two patients in the long
PFN-A group, one sustained a fracture at the distal end of the
nail. This was treated by using a locking plate. The
remaining patient had a perforation of the anterior femoral
cortex. In retrospect this failure was attributed to multiple
failed attempts at distal locking, which however created a
stress riser at that point. A retrograde nailing was performed
for this patient.
All patients were followed up for one year. Five patients
(12.5 %) in the long PFN-A group and three patients (7.5 %)
in the short PFN-A group had died within one year of
undergoing the surgery (p = 0.456).
DISCUSSION
Hip fractures are a serious cause of concern in the
osteoporotic elderly population. The associated mortality
and morbidity with hip fractures is significant
2
. An ever
increasing aged population only compounds this problem.
The number of fragility hip fractures is expected to rise
exponentially with time and so are the corresponding costs
4
.
Almost 90 % of hip fractures are sustained after having a fall
10
. It would be wonderful if one could identify a particular
group of elderly patients who were vulnerable to sustain
fragility fractures around the hip. It has been shown that bone
mineral densitometry (BMD) of the trochanteric region of
femur, obtained using a dual energy X-ray absorptiometry
(DXA), is the best indicator for predicting pertrochanteric
fractures
11
. The mean force required to cause a
pertrochanteric fracture is 3107+/-1066 N, however this
value was arrived at, without considering other factors such
as fall biomechanics and concomitantly acting muscular
forces around the hip joint
11
.
A finite element (FE) model study of femur has shown
pertrochanteric fractures to generate a stress of 621MPa. The
largest stress concentration is at the lag screw hole of the
intramedullary implant. Similarly interfragmentary (IFM)
movements between the proximal and distal fracture
fragments in both axial and transverse direction were highest
in the FE model with pertrochanteric fracture. Such large
forces are responsible for sliding of the fracture fragments on
one another, subsequently leading to opening up of the
fracture. The angle of insertion of a nail during surgery also
is an important factor, since the pre-stress of the nail depends
on the angle of insertion
12
.
Lag screw cut out in the treatment of pertrochanteric
fractures is well documented
13-15
. Ideal lag screw placement
should have a tip-apex distance of less than 25mm to avoid a
screw cut out
16,17
. In a cadaveric study it has been
demonstrated that multiplanar cyclic loading caused the
femoral head to rotate. Eccentrically placed lag screws cause
both rotational cut out and varus collapse. Around 12 % of
pertrochanteric fractures undergo progressive rotation as
they collapse and rotation has been shown to more common
in cases with lag screw out
18,19
. The Proximal Femoral Nail
Antirotation (PFN-A) , as the name implies, has an inbuilt
mechanism which negates the aforementioned rotational
effect. In our study only one patient had a screw cut and who
subsequently underwent a hemiarthroplasty.
Patients who underwent short PFN-A procedures in the
current study had lesser bleeding as compared to the long
PFN-A group. This was a significant finding (p=0.042). It
has been shown that intramedullary fixation procedures lead
to a larger blood loss as compared to extramedullary fixation.
Proximal reaming and insertion of a longer nail leading to
opening of the medullary canal leads to increased blood loss.
Most of the time, such a blood loss is concealed
20
.
The correct technique of PFN-A insertion can avoid the
operating surgeon a lot of grief. Practical suggestions given
Fig. 1: Dimensions of Short PFN-A. Fig. 2: Dimensions of Long PFN-A.
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Malaysian Orthopaedic Journal 2016 Vol 10 No 1 Raval P, et al
26
by Hwang et al., are noteworthy
2
1
. The ethnic background of
the patient should be borne in mind while operating,
especially the Asian population. An excessive anterior bow
i
n a relatively shorter femur should be paid special attention
2
2
. The nail entry point has to be precise. Longer nails are
recommended in elderly patients with significant
osteoarthritis, because the entry point is more anatomically
aligned as compared to the short nails. The operating surgeon
is advised to refrain from hammering the nail in, however
g
entle the hammering process may be
21
.
One of the initial studies done in European clinics on the
efficacy of PFN-A, found it to be an ideal implant in the
treatment of unstable pertrochanteric fractures. This was
especially in regard to the prevention of femoral head
penetration by the screw. Ipsilateral femoral shaft fractures,
due to missed attempts at distal locking have been reported
in this study
23
. Multiple failed attempts at distal locking,
especially when performed free hand not only increase the
total operative time but also create stress risers in the femoral
shaft, which can be sites for potential implant failures in the
future. Authors of the current study had an identical
experience. A retrograde nailing was done in that particular
case. A subsequent study comparing the placement of a
single fixation device in the femoral head in PFN-A did not
confer any additional advantage to that of a PFN (Proximal
Femoral Nail) in which an additional screw is placed
proximally
24
.
In comparison between the efficacies of PFN-A with
Dynamic Hip Screw (DHS), it has been convincingly
reported that a PFN-A is a better implant. Not only is the
PFN-A a biomechanically superior implant, but also the
surgical time and fluoroscopy exposure is less, with fewer
complications. Patients with PFN-A mobilised earlier than
those who had a DHS
25,26
. As regards to mortality, a meta-
analytical study showed no difference in prognosis in either
groups
26
. A recent study comparing PFN-A with DCS has
reported a similar outcome, in favour of the PFN-A
27
.
Aguado-Maestro et al., in their recent study of 200 patients
of pertrochanteric fractures treated with PFN-A, state that
the helical blade system reduced the rate of cut through and
cut out in pertrochanteric fractures and accurate placement of
the helical blade was a key parameter to avoid mechanical
failures
28
. A possible theoretical explanation of the helical
blade failure has been attributed to torsional forces generated
during ambulation. These forces cause a peri implant
osteolysis, subsequently leading to implant failure. This
phenomenon has been named as a “windshield effect”
29
.
Computer navigation has opened newer avenues in the field
of Orthopaedics. In an experimental study of computer
assisted planning and navigation, the operating surgeon is
guided to stay inside a three dimensional ‘safe zone’ while
inserting the helical screw. If inadvertently the surgeon
leaves the safe zone, a warning message, ‘perforation’ is
d
isplayed by the software. Although the fluoroscopic images
and drilling attempts were significantly reduced by using a
computer guided system when compared to a minimally
invasive procedure, there was no difference noted between a
computer guided and an open procedure. Other significant
issue noted was that of a longer surgical duration in a
c
omputer navigation assisted procedure.
One limitation of this study is that many different surgeons
operated upon the patients of either group. This could be a
confounding factor. However the authors of this study can
state that all surgeons involved were very well versed with
the operative technique of PFN-A. There was nobody in the
group who was a novice. Overall the short PFN-A was
favoured by the trainees because of a relatively easier
operative technique. This was shown to be statistically
significant (p = 0.025) (Table III).
Why certain surgeons preferred a long PFN-A for a
pertrochanteric fracture when the standard recommendation
was a short PFN-A, this was one question which had no
satisfactory answers. Informal discussion with the operating
surgeons who preferred a longer nail, revealed that an
anticipation of a sub-trochanteric extension of a seemingly
normal inter-trochanteric fracture forced them to be ‘safe
than sorry’. Now whether additional investigations like a
magnetic resonance imaging (MRI) or a (computed
tomography) CT scan are warranted to see for such sub-
trochanteric extensions is an entirely new topic of discussion
as per the authors of the current study.
CONCLUSION
The treatment of Pertrochanteric fractures will continue to be
a challenge to the treating surgeon. Current literature is in
favour of using an intramedullary device like a PFN-A. The
authors of this particular study would recommend using a
short PFN-A, on account of lesser duration of surgery, hence
lesser anaesthesia time in older patients and also lesser blood
loss. Relatively shorter learning curve amongst trainee
surgeons is another reason why a short PFN-A should be
given a preference over a long PFN-A. However, past
learning experiences will play a significant role in choosing
the correct length of the implant.
CONFLICT OF INTEREST
The authors declare that they have no competing interests.
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