Open Journal of Orthopedics, 2013, 3, 261-268
http://dx.doi.org/10.4236/ojo.2013.36049 Published Online October 2013 (http://www.scirp.org/journal/ojo)
261
Differences in Survival Rates between Different Patterns of
Unstable Pertrochanteric Femoral Fractures*
Amir Herman1,2#, Yair Landau1, Alexander Hazanov3, Tal Segev4,5, Ran Thein1, Nachshon Shazar1
1Department of Orthopedic Surgery, Chaim Sheba Medical Center, Tel-Hashomer, Israel; 2Talpiot Medical Leadership Program,
Chaim Sheba Medical Center, Tel-Hashomer, Israel; 3Department of Anesthesiology, Chaim Sheba Medical Center, Tel-Hashomer,
Israel; 4Department of Vascular Surgery, Chaim Sheba Medical Center, Tel-Hashomer, Israel; 5Sackler Faculty of Medicine, Tel
Aviv University, Tel Aviv, Israel.
Received August 6th, 2013; revised September 6th, 2013; accepted September 21st, 2013
Copyright © 2013 Amir Herman et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Background: Unstable pertrochanter femur fractures are common in orthopedic practice. They pose a surgical chal-
lenge in both reduction and fixation. The fixation devices used are based on hip intramedullary nailing with femur head
lag screw or blade. The aim of this paper is to compare different types of unstable pertrochanter fractures. Materials &
Methods: We retrospectively reviewed 386 unstable pertrochanter femur fractures surgically treated in our hospital
from 2000 to 2009. These included 62 (16.1%) unstable pertrochanter fractures with fractured lesser trochanter
(31.A2-2, 31.A2-3); 63 (16.3%) reverse oblique fractures (31.A3-1), 51 (13.2%) transverse fractures (31.A3-2), 145
(37.6%) comminuted fractures (31.A3-3) and 65 (16.8%) subtrochanter fractures. We compared survival rates between
fracture types. The clinical characteristics, surgery immediate outcome (e.g., tip apex distance, reduction quality), and
long term results, i.e., complications were also compared between fracture types. Results: Survival analysis showed
that the fracture types can be grouped into low and high risk fracture types. The former group included, reverse oblique
and comminuted fractures. Lesser trochanter, transverse and subtrochanter fractures were included in the high risk
group. The survival estimates for five years were 64.6% and 49.3% for the low and high risk fracture types, respectively
(p value = 0.008). Multivariate survival analysis showed that the hazard ratio for the high risk fracture group was 1.9
(95% CI = 1.37 - 2.67). No differences were found between unstable pertrochanter femur fractures with regards to
clinical and epidemiology characteristics. Optimal tip apex distance (TAD) of less than 25 mm was found in 66.7%,
57.1% and 66.7% of lesser trochanter, reverse oblique and sutrochanter fractures, respectively. TAD of less than 25 mm
was found in 81.2% of both transverse and comminuted fractures (p value = 0.032). No statistically significant differ-
ence was found between fracture types, in regards to complication or revision rates. Conclusions: Survival rates were
higher in patients suffering from reverse oblique or comminuted pertrochanteric fractures. No differences were found
between fracture types, in regards to clinical and other outcome parameters.
Keywords: Intertrochanteric Fractures; Survival; Fracture Classification
1. Introduction
Pertrochanteric fractures are among the most widely
treated orthopedic injuries. Their annual incidence is ex-
pected to reach 500,000 by 2040, in the US alone [1].
About half of this is estimated to be unstable factures [2].
The AO/OTA classification system divides pertrochan-
teric fractures into several groups: simple pertrochanteric
(31.A1), pertrochanteric with lesser trochanter fracture
(31.A2) and complex pertrochanteric fractures (31.A3)
[3]. Each of these three groups is further divided into
three groups, consisting of a total of nine different fracture
patterns. These patterns are commonly divided into stable
pertrochanteric fractures (31.A1 fracture group and 31.A2-
1 subtype) and unstable pertrochanteric fractures (31.A2-
2 and 31.A2-3 subtypes and 31.A3 fracture group) [4-6].
Fixation devices available for pertrochanteric fractures
vary from intra-medullary devices and extra-medullary
plate both with femur head screw. The extra-medullary
*Conflict of interest statement: No benefit in any form has been or will
b
e received from a commercial party related directly or indirectly to the
subject of this manuscript.
#Corresponding author.

Differences in Survival Rates between Different Patterns of Unstable Pertrochanteric Femoral Fractures 262
device was shown to have fewer complications in stable
pertrochanteric fractures. Patients with unstable pertro-
chanteric fractures were shown to benefit from intrame-
dullary fixation devices such as the Cephalomedullary
nail, Gamma nail, Y nail among other [5,7-20].
Subtrochanteric fractures are defined as fractures with-
in the immediate 5 cm distal to the lesser trochanter. As
opposed to femur shaft fractures, these fractures require
fixation of the femoral head-neck-shaft complex. Frac-
tures of the subtrochanteric region often are fixed by in-
tramedulary proximal femur fixation devices. As such
these factures can be included as part of the unstable per-
subtrochanteric fracture patterns [21].
Several authors described their experience of different
unstable pertrochanteric fractures. These include a recent
review by Lundy focusing on subtrochanteric fractures
and a description of open reduction in treating subtro-
chanteric fractures [2]. Other authors focused on reverse
oblique or transverse fracture types [6]. We are unaware
of any work comparing the survival among different sub-
types of unstable pertrochanteric fractures.
In this report we compare between the different pat-
terns of unstable per-subtrochanteric fractures. We com-
pare the survival rates, epidemiology, reduction achieved,
screw placement, complications and revision rates be-
tween the different fracture types.
2. Patients & Methods
The study presented is a retrospective study based on na-
tional mortality registry and our hospital admission and
outpatient-clinic files. The study was approved by our
institute’s internal review board (IRB) ethics committee.
Since this is a retrospective study, patients’ informed con-
sent was not required by the IRB.
Between 2000 and 2009, 386 unstable pertrochanteric
fractures were operated in our institute. These consisted
of 62 (16.1%) pertrochanteric fractures in which the les-
ser trochanter was fractured and the fracture was defined
as unstable (31.A2-2 and 31.A2-3). There were 63 (16.3%)
reverse oblique fractures (31.A3-1), 51 (13.2%) transver-
es pertrochanteric fractures (31.A3-2) and 145 (37.6%)
of comminuted fractures (31.A3-3). Subtrochanteric frac-
tures included 65 (16.8%) fractures.
The Fractures had been fixed by means of the Targon
proximal femur (Targon PF) device (Aesculap, Tuttlin-
gen, Germany) or with the antirotation trochanteric nail-
ing system (ATN) device (dePuy, Warsaw, IN, USA).
Both of which are double screw intramedullary fixation
devices. All surgeries were performed in accordance to
standard surgery technique and the manufacturer’s rec-
ommendations.
The radiology computerized achieve was used for clas-
sification of fractures according to the OTA/AO classifi-
cation system [3]. Patterns were classified by two inde-
pendent researchers (A.O and Y.L). The senior author
(N.S) was consulted whenever consensus was not rea-
ched. Radiology measurements were performed includ-
ing the tip apex distance and placement of the center of
the lag screw within the head-neck interface “Safe-zone”
(defined as the second quarter from the bottom) [22].
Acceptable reduction was considered as translation of
less than 20 mm in any plane as measured by the medial
cortex in anterior-posterior radiography view or anterior
cortex on axial radiography view.
Statistical analysis was performed by an experienced
biostatistician (A.H.). Data analysis was conducted using
SPSS© 16 (SPSS©, Chicago, IL). Categorical data are
presented as frequency count (percent of available data).
Comparisons of categorical variables between fracture
types were performed using either the chi-square test or
the Fisher’s exact test. The latter was used when expec-
ted count in any cell was less or equal five. Continuous
variables are presented as mean (±standard deviation).
Comparisons of continuous variables among fracture pat-
terns were performed using the Kruskal-Wallis test. Com-
parisons of paired data, mainly the increase in mobility
aids before and one year after surgery, were performed
using the Wilcoxon rank sign test. Survival data are pre-
sented using the Kaplan-Meier survival curves. Kaplan-
Meier survival estimates were used for one and five years
survival along with 95% confidence interval (95% CI).
Comparisons between survival curves were done by the
log-rank test.
Data were extracted by reviewing of the patients’ ad-
mission and out-patients clinic electronic files. Compli-
cations, comorbidities, use of walking aids and recovery
parameters were extracted from the hospital records. The
national mortality registry was consulted for mortality
status and date. Patients that were not registered as de-
ceased were considered as censured at the date of the in-
quiry.
Multivariate survival analysis was performed with the
Cox proportional hazards model. The independent co-
variates in the model were fracture group (according to
high or low risk fracture type), ASA score and Age group
—up to 60 years old (46 pts, 11.9%), 60 - 80 years old (158
pts, 40.7%), above 80 year old (182 pts, 47.1%). Results
are reported as hazard ratios and their 95% confidence in-
tervals. Hazard ratio should be interpreted as relative risk,
so that hazard ratio above one means excessive risk.
Data were not available for all patients in all variables
measured. The numbers of patients used for analysis of
each variable are given within the summary tables. In each
analysis frequencies and percents were calculated from
available data. For example, for epidemiologic and clini-
cal presentation parameters, percents were calculated from

Differences in Survival Rates between Different Patterns of Unstable Pertrochanteric Femoral Fractures 263
the entire patients’ population. Complications and revi-
sion rates are calculated from a subset of patients which
included patients that either had a complication or com-
pleted at least one year of follow-up and showed signs of
union on X-ray radiography.
3. Results
Between 2000 and 2009, 386 unstable pertrochanteric
fractures were operated in our institute. These included
95 (24.6%) fractures in men and 291 (75.4%) fractures in
women. Mean age at surgery was 76.16 years (±15.2).
Mean American society of anesthesiologists (ASA) score
was 2.75 (±0.61), where 124 patients (32.2%) and 225
patients (58.4%) had ASA scores of 2 and 3, respectively.
Patients with transverse fractures (31.A3-2) had higher
ASA scores (p value = 0.026). Mechanism of injury was
low energy fall in 175 fractures (87.1%). Initial treatment
at the emergency ward included skeletal traction in 145
fractures (71.8%). Skeletal traction was performed more
often in reverse oblique, comminuted or subtrochanter frac-
tures. This difference was found to be statistically signi-
ficant (p value = 0.001) Epidemiological and clinical data
according to fracture types are presented in Table 1.
Of the 386 fractures treated, 254 fractures (65.8%)
were treated by the Targon PF © device, while 132 frac-
tures (34.3%) were fixed using the ATN © device. No
statistically significant difference was found between the
fracture types. The nail length was found to be longer
(300 mm - 340 mm) in fixation of subtrochanteric and
comminuted fractures (Table 2).
Immediate surgical outcome varied between fracture
types. Tip Apex Distance (TAD) was found to be below
25 mm in about 81% of comminuted and transverse frac-
Table 1. Demographic and clinical characteristics (Total = 386 patients).
Fractured Lesser
Trochanter
(A2.2 & A2.3) N = 62
Reverse Oblique
(A3.1) N = 63
Transverse
(A3.2) N = 51
Comminuted
(A3.3) N = 145
Subtrochanteric
N = 65 P value
Gender
Male
Female
20 (32.3%)
42 (67.7%)
11 (17.5%)
52 (82.5%)
9 (17.6%)
42 (82.4%)
35 (24.1%)
110 (75.9%)
20 (30%)
45 (69.2%) 0.173
Age 78.9 (±12.5) 79.0 (±9.8) 77.5 (±14.2) 75.8 (±14.8) 70.4 (±21.1) 0.243
Side
Left
Right
32 (51.6%)
30 (48.4%)
32 (50.8%)
31 (49.2%)
29 (56.9%)
22 (43.1%)
78 (53.8%)
67 (46.2%)
34 (52.3%)
31 (47.7%) 0.971
ASA score 2.69 (±0.64) 2.78 (±0.60) 3.00 (±0.566) 2.68 (±0.61) 2.72 (±0.50) 0.026
Above one year follow-up 26 (41.9%) 26 (41.3%) 19 (37.3%) 72 (49.7%) 22 (34.4%) 0.253
Skeletal traction (N = 202) 3 (7%) 11 (40.7%) 5 (17.9%) 25 (32.9%) 13 (46.4%) 0.001
Diabetes Mellitus (N = 201) 10 (23.8%) 4 (14.8%) 5 (17.9%) 19 (25.0%) 5 (17.9%) 0.764
Mechanism of injury
(N = 202)
Low energy (fall)
High energy
37 (86%)
6 (14%)
25 (92.6%)
2 (7.4%)
24 (85.7%)
4 (14.3%)
68 (89.5%)
8 (10.5%)
21 (77.8%)
6 (22.2%)
0.327
Table 2. Surgery and post operative outcome parameters.
Fractured Lesser
Trochanter
(A2.2 & A2.3) N = 62
Reverse Oblique
(A3.1) N = 63
Transverse
(A3.2) N = 51
Comminuted
(A3.3) N = 145
Subtrochanteric
N = 65 P value
IM Nail Type
Targon PF
AT N
34 (53.9%)
29 (46.1%)
49 (77.8%)
14 (22.2%)
28 (54.9%)
23 (45.1%)
96 (66.2%)
49 (33.8%)
47 (73.4%)
17 (26.6%)
0.13
Nail length
Standard (200 - 240 mm)
Long (300 - 340 mm)
56 (90.3%)
6 (9.7%)
58 (92.1%)
5 (7.9%)
48 (94.1%)
3 (5.9%)
109 (75.2%)
36 (24.8%)
12 (19.0%)
51 (81.0%)
0.0001
Tip Apex distance ≤ 25 mm
(N = 235) 28 (66.7%) 24 (57.1%) 29 (81.2%) 69 (81.2%) 20 (66.7%) 0.032
Lag screw within “safe-zone”
(N = 378) 53 (85.5%) 50 (80.6%) 42 (87.5%) 120 (84.5%) 49 (76.6%) 0.506
Reduction not achieved (N = 383) 6 (9.8%) 17 (27.0%) 10 (19.6%) 35 (24.1%) 12 (19.0%) 0.134
Mobility points change from pre to
1 year post surgery (N = 60) 1.66 (±1.23) 1.77 (±1.30) 2.14 (±1.06) 1.90 (±1.33) 0.75 (±1.35) 0.174
Walking 1 year after surgery
(N = 77) 72% - 93.5% 15 (100%) 8 (88.9%) 11 (100%) 25 (89.3%) 13 (92.9%) 0.566

Differences in Survival Rates between Different Patterns of Unstable Pertrochanteric Femoral Fractures 264
tures. The TAD was below 25 mm in only 57% - 66% of
lesser trochanter, reveres oblique and subtrochanteric
fractures. This difference was found to be statistically
significant (p value = 0.032). However, 76% to 87% of
the lag screws were placed within the head-neck inter-
face “safe-zone”. This difference was not found to be sta-
tistically significant (p value = 0.506). Reduction was not
achieved in 7.6% patients. No statistically significant dif-
ference was found between fracture types (p value =
0.386).
Seventy two patients (93.5%) walked of 77 patients
whose mobility status was recorded one year after sur-
gery. Mobility aids used as recorded by the Parker score
increased by a mean of 1.6 points (±1.3) one year after
surgery. Sixty nine percent of the patients used a walking
frame one year after surgery (Figure 1). No statistically
significant difference was found in regards to mobility
status between fracture types (Table 2).
One hundred and ninety one patients had either at least
one year of follow-up with documented fracture union or
any complication. Common complications included 14
(7.3%) fractures that had cutout, 10 fractures (5.2%) that
had hardware failure and 7 fractures fixed with internal
rotation above 30 degrees. Less common complications
included deep wound infection, secondary loss of reduc-
tion, and fractures non-unions, with rates of 5 (2.6%), 5
(2.6%) and 3 (1.6%) fractures, respectively. No statisti-
cally significant difference was found between fracture
types (Table 3).
Thirty two patients (16.8%) of the aforementioned 191
patients had revision surgery. Common revision types
included 14 (7.3%) hardware removals, 7 (3.7%) arthro-
Figure 1. Walking aids score: where no aids, one aid, two aids, walking frame and wheel chair received a score of 1 - 5 in an
ascending order. Mean increase in ambulation score from preoperative to 1 year after surgery was 1.63 points (±1.32). This
difference was found to be statistically significant (p value = 0.0001). No statistically significant difference was found between
fracture patterns.
Table 3. Complications.
Total N = 191
Fractured Lesser
Trochanter (A2.2
& A2.3) N = 34
Reverse Oblique
(A3.1) N = 31
Transverse (A3.2)
N = 23
Comminuted
(A3.3) N = 78
Subtrochanteric
N = 25
P
value
Cut out—14 pts (7.3%) 3 (8.8%) 2 (6.5%) 4 (17.4%) 5 (6.4%) --- 0.232
Hardware failure—10 pts
(5.2%) 4 (11.7%) 2 (6.5%) --- 4 (5.2%) --- 0.278
Nonunion—3 pts (1.6%) 1 (2.9%) --- 1 (4.3%) --- 1 (4.0%) 0.16
Deep wound infection
—5 pts (2.6%) --- --- --- 4 (5.1%) 1 (4.0%) 0.508
Secondary loss of
reduction 5 pts (2.6%) 1 (2.9%) 1 (3.2%) --- 1 (1.3%) 1 (4.0%) 0.674
Internal rotation—7 pts
(3.7%) 3 (8.8%) 2 (6.5%) --- 1 (1.3%) 1 (4.0%) 0.172
Other—3 pts (1.5%) 1 (2.9%) --- --- 1 (1.3%) 1 (4.0%) 0.564
Total complications—47
pts (24.6%) 13 (38.2%) 7 (22.6%) 5 (21.7%) 16 (20.5%) 6 (24.0%) 0.369
Table 3 includes surgical complications and revision surgery. Other complications include one patient with pain that required revision, 1 patient with fracture at
the lower end of the fixation device, and one patient with superior placement of the fixation device that required revision. No cases of deep vein thrombosis
were reported.

Differences in Survival Rates between Different Patterns of Unstable Pertrochanteric Femoral Fractures 265
plasties and 5 (2.6%) rotational corrections. No statisti-
cally significant difference was found between fracture
types (Table 4).
One year and five years survival of the entire cohort
were 79.6% (95% CI of 75.1% - 84.2%) and 48.9% (95%
CI of 42.3% - 56.4%), respectively. Comparing survival
between specific inter-trochanteric fractures, no statisti-
cally significant difference was found (p value = 0.07,
Table 5). The fractures were grouped into high and low
risk fracture types, according to survival. The low risk
fracture types included reverse oblique fractures (31.A3-
1) and comminuted fractures (31.A3-3). High risk frac-
ture types included lesser trochanter unstable fractures
(31.A2-2 and 31.A2-3), transverse fractures (31.A3-2)
and subtrochanteric fractures (32 either A, B or C). One
year and five years survival for the low risk fracture
types were 86% (95% CI 81.4% - 90.8%) and 64.6%
(95% CI 57.4% - 72.6%), respectively. One year and five
years survival for the high risk fracture types were 76.4%
(95% CI, 70.4% - 82.9%) and 49.3% (95% CI, 41.0% -
59.2%). This difference was found to be statistically sig-
nificant (p value = 0.008, Figure 2).
Multivariate analysis by the Proportional hazards mo-
del showed that the high risk fracture group was asso-
ciated with higher mortality risk. Setting the low risk
fracture group to have hazard ratio of one (as baseline)
the hazard ratio for the high risk fracture group was 1.9
(95% CI = 1.37 - 2.67). This difference was found to be
statistically significant (p value = 0.0001). The hazard
rate associated with age 60 - 80 was 17.7 (95% CI = 4.3 -
73.1). The hazard rate associated with age above 80 years
old was 19.6 (95% CI = 4.7 - 80.7). The hazard rate as-
sociated with each point of the ASA score was 1.152
(95% CI = 0.88 - 1.5). This was not found to be statisti-
cally significant (p value = 0.29).
4. Discussion
In this manuscript, it was shown that survival rates dif-
fered between different types of unstable pertrochanteric
fractures. These fractures could be divided into low and
high risk fracture types. The low risk group includes: re-
verse oblique and comminuted fractures. The high risk
fracture types include: lesser trochanter, transverse and
subtrochanteric fractures. No difference in clinical or epi-
demiologic characteristics was found in order to explain
the difference in survival. No difference was found in
complication and revision rates that could also elucidate
the survival difference.
In previous works, other authors focused mainly on
Table 4. Revisions.
Total N = 191 pts
Fractured Lesser
Trochanter
(A2.2 & A2.3) N = 34
Reverse Oblique
(A3.1) N = 31
Transverse
(A3.2) N = 23
Comminuted
(A3.3) N = 78
Subtrochanteric
N = 25 P value
Total Hip replacement
—3 pts (1.6%) 2 (5.9%) --- 1 (4.3%) --- --- 0.086
Hemiarthroplasty—4
pts (2.1%) --- --- --- 4 (5.1%) --- 0.441
Exchange nail—4 pts
(2.1%) --- --- 1 (4.3%) 2 (2.6%) 1 (4.0%) 0.533
Hardware removal—11
pts (5.7%) 3 (8.8%) 3 (9.4%) 1 (4.3%) 4 (5.1%) --- 0.552
Nail removal and
plating—3 pts (1.6%) --- --- 2 (8.7%) --- 1 (4.0%) 0.018
Rotation correction—5
pts (2.6%) 2 (5.9%) 1 (3.2%) --- 1 (1.3%) 1 (4.0%) 0.455
Soft tissue revision due
to infection 1 pt (0.5%) --- --- --- 1 (1.3%) --- 1.00
Total revisions—32 pts
(16.8%) 7 (20.6%) 4 (12.9%) 5 (21.7%) 12 (15.4%) 4 (16.0%) 0.876
Table 5. Survival estimates (95% confidence intervals).
Total = 386 patients
Fractured Lesser
Trochanter
(A2.2 & A2.3) N = 62
Reverse Oblique (A3.1)
N = 63
Transverse (A3.2)
N = 51
Comminuted (A3.3)
N = 145 Subtrochanteric N = 65
Six months 95.2% (90% - 100%) 93.5% (87.6% - 99.9%)88.2% (79.8% - 97.5%)91% (86.5% - 95.8%) 80% (70.8% - 90.3%)
One year 77.4% (67.6% - 88.5%) 90.3% (83.3% - 98%)74.5% (63.4% - 87.5%)84.1% (78.4% - 90.3%) 76.9% (67.3% - 87.9%)
Five years 55.7% (42% - 73.9%) 63.2% (50.9% - 78.4%)37.9% (22.8% - 62.8%)64.5% (56% - 74.3%) 50.5% (38.5% - 66.3%)
P value for survival curves comparing all the fracture types = 0.07.

Differences in Survival Rates between Different Patterns of Unstable Pertrochanteric Femoral Fractures 266
(a) (b)
Figure 2. Kaplan-Meier survival curves. Low risk fracture types include AO types A3.1 (reverse oblique), A3.3 (Commin-
uted). High risk fracture type include AO types A2 (lesser trochaner fracture), A3.2 (transverse), and subtrochanteric frac-
tures. The difference in survival was found to be statistically significant (p value = 0.008). (a) Kaplan Meier survival curves
after fixation—by fracture type. (b) Kaplan Meier survival curves after fixation—by risk group.
describing series of specific unstable fractures, without
comparing between them. Reported complications of un-
stable pertrochanteric fractures fixation included cutouts
(4% - 20%), femoral shaft fractures (0% - 10%) and no-
nunions (1% - 2%) [4]. Subtrochanteric fracture fixation
had shown similar results [21,23]. These complication
rates are comparable to the rates presented in this study.
In our work, no statistically significant difference was
found between fracture types in reviewing postoperative
complications.
Some authors studied factors influencing the mortality
of patients after internal fixation of pertrochanteric frac-
tures. Forte et al. have examined the ninety day mortality
in patients treated by internal fixation of pertrochanteric
fracture. They have shown that patients treated at a low
volume versus high volume institutes had mortality rates
for ninety days of 24.4% and 12.9%, respectively [24].
These survival rates are comparable to the survival pre-
sented in this study. Donegan et al. has shown that higher
ASA was associated with higher in hospital mortality
rates. This was due to higher medical complications in
patients with higher ASA scores [25]. In our study no cli-
nically significant difference in ASA score was found be-
tween fracture types.
We found the lack of successful reduction in 7.6% of
patients, with no statistically significant difference among
fracture types. This result does not indicate as to the dif-
ficulty in achieving reduction, only the final results. This
finding is especially important since the reduction quality
is considered by many to be one of the major criteria in
preventing further complications [26-28]. The TAD was
found to differ between fracture types. This did not in-
fluence the failure rates between fracture types. This fin-
ding is in contradiction to other authors who have shown
that TAD above 25 was associated with higher rates of
cutouts [26,29].
Recently, we reported a new radiographic measure for
correcting lag screw position. Using polar to Cartesian co-
ordinates transformation, we were able to devise a femur
head-neck interface “safe zone” for the center of the lag
screw. In short, this safe zone is the second quarter (from
the bottom) of the head-neck interface line. In this data-
set 76% to 87% of the lag screws were found within the
head-neck “safe-zone”. This parameter did not differ
among fracture types. This finding can explain why there
were no differences in the rates of cutout between dif-
ferent fracture patterns.
The main drawback of the article is the fact that it is
retrospective. As such, some data were not available,
either not accessible or it was not recorded to begin with.
However, the retrospective nature of the analysis enabled
us to include maximum patients in our study. Further, the
main result of the study, namely survival rates, was ex-
tracted from the national databases which are independ-
ent from the study design.
We believe that our results offer some new conclu-
sions regarding unstable pertrochanteric fractures. We
found that unstable pertrochanteric fractures are similar
in demographics and surgery outcome. Also their com-
plications and revision rates are similar. However, these
fractures differ in survival of patients after surgery.
5. Acknowledgements
This study was funded by the Talpiot medical leadership
program of the Chaim Sheba, Tel-Hashomer, Hospital.
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