- Email: [email protected]
Accuracy of a Simple Digital Templating in Primary Uncemented Total Hip Arthroplasty
Chin Med Sci J September 2015
Vol. 30, No. 3 P. 150-155
CHINESE MEDICAL SCIENCES JOURNAL ORIGINAL ARTICLE
Accuracy of a Simple Digital Templating in Primary Uncemented Total Hip Arthroplasty△ Hai-bo Si, Yi Zeng, Fei Cao, Fu-xing Pei, and Bin Shen* Department of Orthopaedics, West China Hospital, Sichuan University, Chengdu 610041, China
Key words: arthroplasty; hip; digital templating; preoperative planning; accuracy Objective To introduce a simple preoperative digital templating in uncemented total hip arthroplasty (THA) and to determine its accuracy for preoperative size selection of the prostheses. Methods A prospective study of digital planned THAs was performed on 90 hips with different types of prostheses from August 2013 to Angust 2014. The plastic templates of different types of prostheses were scanned for desired digital templating and the scanned images were then processed to the transparent, digital templates using Photoshop software. We calibrated the scales of the digital templates with the preoperative radiographs, and then selected the right size of the component. The preoperatively digital planned component sizes were compared to the actual sizes used in the operation, as well as the preoperatively traditional planned sizes. Results In either cup or stem templating, no difference was found among the groups with different types of prostheses, and the accuracy of digital templating was statistically higher than traditional templating. In cup templating, digital planned and implanted cup sizes were identical in 43.33% of the cases, 78.89% of the cup sizes were predicted within 1 size (± 2mm) and 95.56% were predicted within 2 sizes (±4 mm), all significantly higher than the results of traditional planned sizes (30.00%, P=0.044; 61.11%, P=0.007; 82.22%, P=0.004). The exact femoral stem size was predicted in 40.00% of cases using the digital templating, 84.44% of stem sizes were predicted within 1 size, and 93.33% within 2 sizes, better than using traditional templating (25.56%, P=0.028; 53.33%, P＜0.001; 77.77%, P=0.003). Conclusion This simple digital preoperative templating is an accurate and reproducible process to preoperatively predict the implant size of uncemented THA.
Chin Med Sci J 2015; 30(3):150-155
T
OTAL hip arthroplasty (THA) is one of the most
prostheses, precise preoperative planning has become vital
successful procedures for surgical treatment of a
for successful THA, and more emphasis has been placed on
diseases.1-3
increasing
selecting the accurate implant size to avoid facture with a
number of THAs and the use of uncemented
component too large or subsidence with a component too
variety
of
hip
With
small.4,5 Traditionally, plain radiographs and plastic tem-
Received for publication November 24, 2014.
plates with fixed magnification factors of 115% or 120%
△Supported by the Health Research Program of Ministry of Health
were used to achieve these goals, but the uncontrolled
(201302007).
magnification of the plain radiographs from different
*Corresponding author Tel: 86-13881878767, E-mail: [email protected]
equipment often result in errors in preoperative templating.
Vol. 30, No.3
CHINESE MEDICAL SCIENCES JOURNAL
151
The outcomes of the operation would be affected if the
until the scale of the digital template layer coincide with the
unmatched
radiograph’s scale (Fig. 2A). The digital template image
component
according
to
the
inaccurate
preoperative measurement is used.6-8
was moved and rotated to select the right size of the
Digital radiography is currently replacing traditional
component. Select the acetabular size that matches the
radiography in many hospitals, and digital templating was
contour of the patient’s acetabulum without excessive
proposed as a method to electronically overlay templates
removal of subchondral bone. The medial position of the
from a digital library on clinical radiographs for arthroplasties.9
acetabular template is at the teardrop and the inferior
Combination of digital radiography and digital templating
margin at the level of the obturator foramen (Fig. 2B).
has the potential to eliminate the errors associated with the
Select the femoral size that matches most precisely the
manual manipulation of plastic templates and plain
contour of the proximal canal, restore the horizontal and
radiographs. To date, many studies have evaluated the
vertical offset and fit (Fig. 2C). Template the femur on
accuracy of digital templating using expensive orthopaedic
the lateral view in the similar manner to ascertain
10,11
This prospective study
whether the implant determined on the anteroposterior
introduces a simple digital templating and determines how
radiograph can be inserted without excessive bone
well preoperative size selection of THAs of this digital
removal (Fig. 2D).
software in uncemented THA.
templating correlates with the size actually implanted.
All the digital templating was performed prospectively by the first author, who is familiar with the Photoshop software. In addition, preoperative planning was also performed
MATERIALS AND METHODS
traditionally, using the plain radiographs and plastic templates,
Preparation of digital templating
by the second author.
Plastic templates of Corail, Summit and Tri-lock femoral stem and Pinnacle acetabular cup (DePuy, USA) were used.
Total hip arthroplasty
These template overlays were scanned for desired digital
A total of 90 planned size selections were recorded
templating using a standard tabletop scanner and the
prospectively for selective uncemented THAs and were
scanned images were saved as JPEG (.jpg) files. The
compared with the actual size implanted at surgery and
scanned images were then opened in Photoshop CS6
with traditional preoperative size selections from August
software (Adobe Systems Inc, San Jose, CA, USA), the
2013 to August 2014. Patients underwent a staged or
blank areas were selected by the “Magic Wand tool” and
simultaneous THA used only template for the first hip. The
deleted using the “Delete” key. The measure image, ruler,
90 uncemented THAs were performed by a senior joint
size, and other markers were remained, the “Erase” tool
surgeon (the corresponding author) who has implemented
was used to erase the extra spots when necessary. Finally,
more than 800 THAs successfully using a posterior-lateral
the transparent, digital templates were named (type-size)
approach, the preoperative diagnoses were osteoarthritis
and saved as PNG (.png) files (Fig. 1).
or avascular necrosis of femoral head. All the patients
Preoperative templating
liner and ceramic femoral head (DePuy, USA). Thirty patients
The preoperative digital radiographs of the hips were
received Corail femoral stem (Group A), 30 received Summit
obtained by digital radiography. Care was taken to ensure
femoral stem (Group B), and 30 received Tri-lock femoral
weight bearing radiographs were well centered with the
stem (Group C) (DePuy, USA). The sizes of acetabular cup
coccyx
and femoral stem used in the operation were recorded.
received a Pinnacle cup, high-cross-linked polyethylene
pointing
just
above
the
symphysis
pubis,
symmetrical obturator foramina, and with both feet in 10° to 15° of internal rotation. The digitized radiographs were
Statistical analysis
stored in the hospital image station, and downloaded to our
Statistical analysis was performed with SPSS 18.0 (SPSS,
computer saved as JPEG files.
Inc, Chicago, IL, USA) software by the third author, who
The JPEG images of hip radiograph and the digital
did not participate in planning or surgery. All categorical
templates were imported into Photoshop software. The
variables, such as gender, operative side and the accuracy
preoperative hip radiograph was opened as the initial
of planned sizes analyzed against the final component sizes
image and set as under layer, the digital template image
at surgery, were compared using the Chi-square test.
was then moved and placed on preoperative radiograph,
Continuous variables (age) were expressed as means ±SD,
scaled by the “free transform” tool, with the SHIFT key
and comparisons were employed using 2-sided T-test for
pressed to keep the same aspect ratio and avoid distortion,
paired groups. P<0.05 was considered statistically significant.
152
CHINESE MEDICAL SCIENCES JOURNAL
September 2015
Figure 1. Preparation of the transparent, digital templates of Pinnacle acetabular cup (A) and Corail femoral stem (B).
Figure 2. Preoperative digital templating. A. Calibration of the scale of the digital template and the preoperative radiograph layer; B. Digital templating of the acetabular cup size; C. Digital templating of the femoral stem size on the anteroposterior view; D. Digital templating of the femoral stem size on the lateral view.
of the cases in digital templating and 25.56% in traditional
RESULTS
group. The increments of the manufactured Corail, Summit and Tri-lock stem are 1 sizes. 84.44% of stem sizes were
The average age of group C was statistically lower than
predicted within 1 size, and 93.33% within 2 sizes in digital
that of group A (P=0.041, Table 1), but no significant
templating. In comparison, 53.33% within 1 size and
differences in sex and operated side between the groups
77.77% with in 2 sizes, respectively, were predicted in
were found (all P>0.05). The digital and traditional
traditional templating. The accuracy of digital templating
templating results of either cup or stem showed no
for femoral stem size was statistically higher than
difference among group A, B, and C (all P> 0.05, Table 2).
traditional templating (P<0.05, Table 3).
In acetabular cup templating, digital planned and implanted cup sizes were identical in 43.33% of the cases.
Table 1. Characteristics of the included patients
The increments in size of the manufactured Pinnacle cup are 2 mm, a total of 78.89% of cup sizes were predicted within 1 size (± 2mm), and 95.56% were predicted within 2 sizes (±4 mm) in digital templating. Whereas, traditional planned and implanted sizes were identical in 30.00%, within 1 size in 61.11% and within 2 sizes in 82.22%. The accuracy of digital templating for acetabular cup size was
Sex
Side
(M:F)
(L:R)
Groups
n
Age (yrs)
A
30
56.10±12.86
21: 9
15:15
B
30
54.83±12.80
17:13
17:13
14:16
19:11
C
30
*
49.40±10.17
statistically higher than that of traditional templating
Group A received Corail femoral stem, group B received
(P<0.05, Table 3).
summit femoral stem, and group C received Tri-lock femoral
The exact femoral stem size was predicted in 40.00%
stem; *P<0.05 compared with group A.
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CHINESE MEDICAL SCIENCES JOURNAL
153
Table 2. The templating results of the digital and traditional groups with different types of prostheses [n=30, n(%)] Exact Size Groups Cup
Stem
±1 size
±2 sizes
Traditional
Digital
Traditional
Digital
Traditional
Digital
A
10 (33.33)
14 (46.67)
18 (60.00)
24 (80.00)
25 (83.33)
29 (96.67)
B
8 (26.67)
12 (40.00)
18 (60.00)
23 (76.67)
24 (80.00)
28 (93.33)
C
9 (30.00)
13 (43.33)
19 (63.33)
24 (80.00)
25 (83.33)
29 (96.67)
A
8 (26.67)
13 (43.33)
17 (56.67)
26 (86.67)
24 (80.00)
28 (93.33)
B
8 (26.67)
11 (36.67)
15 (50.00)
24 (80.00)
23 (76.67)
27 (90.00)
C
7 (23.33)
12 (40.00)
16 (53.33)
26 (86.67)
23 (76.67)
29 (96.67)
Table 3. The total templating results of the digital and traditional groups [n(%)] Cup
Accuracy
Traditional
Digital
Exact size
27 (30.00)
39 (43.33)
± 1 size
55 (61.11)
± 2 size
74 (82.22)
Stem
P
P
Traditional
Digital
0.044
23 (25.56)
36 (40.00)
0.028
71 (78.89)
0.007
48 (53.33)
76 (84.44)
<0.001
86 (95.56)
0.004
70 (77.77)
84 (93.33)
0.003
accuracy was significantly higher than traditional manual templating.
DISCUSSION
A few studies investigated the manual onlay templating
Preoperative templating is regarded as an essential
of uncemented THA. It has been reported that the cup was
step for successful implantation of the hip prostheses.
accurate in 20%-51% of cases, which increased to 60%-
Traditional templating is mainly based on plastic templates
100% within 1 cup size, and the femoral stem was accurate
and plain radiographs, the plastic templates have a fixed
in 40%-79% of cases, which increased to greater than
magnification of 115% or 120% usually, but the magnification
85%-100% within 1 femoral stem size.12,14-16 More studies
of the plain radiographs from different device is difficult to
have
investigated
digital
templating
in
uncemented
control, and it will result in errors in preoperative templating.6-8
THA.
Furthermore, if the unmatched component according to the
cup had an accuracy of 25%-84%, which was 60%-91%
inaccurate preoperative templating was used, especially by
within 1 size, and more than 90% within 2 sizes. The
inexperienced joint surgeons, intraoperative facture (with
accuracy for the femoral stem was 35%-62% in femoral
too large a component) or postoperative subsidence (with
stem, which was 74%-98% within 1 size, and greater than
too small a component) might occur, and the postoperative
95% within 2 sizes. The et al20 showed a higher accuracy of
rehabilitation would be affected.4,
5
10,12,17-20
They found that templating of the acetabular
The introduction of
cup estimation in digital templating compared with manual
digital radiography is advantageous in preoperative planning
onlay technique, but there were no differences in stem
for THA since it shows good intra- and inter-observer
evaluation. In these studies, Trauma Cad templating system
reliability, as well as provides higher imaging quality
(Orthocrat Ltd, Petach-Tikva, Israel), Orthoview software
through the possibility of image editing and individual
(Meridian Technique Ltd., Southampton, United Kingdom)
referencing.12,
However, the commercial orthopaedic
or Hyper ORTHO software (Rogan-Delft BV, Venendaal,
software is expensive, relies on the digital library and needs
Netherlands) were adopted. These commercial orthopaedic
to design for each application, and whether the digital
software have the disadvantage of depending on the digital
templating using these commercial orthopaedic software is
library, high-cost, and limitations in software design for
superior to manual templating in predicting prosthesis size
each application.
13
is still controversial.10,11 In this study, we prospectively
The application of Photoshop has been reported in
investigated the accuracy of a simple digital templating in
optimizing radiographic images,21 preoperative surgical
estimating the size of the hip prostheses, and found that its
planning,9 and three-dimensional reconstruction of anatomic
154
CHINESE MEDICAL SCIENCES JOURNAL
September 2015
structures based on segmented MR images.22 The techniques
alternative for the existing complex preoperative digital
for image rotation, sizing, and the use of layers in these
templating of THA.
studies are similar to those used in the current study. Using
In conclusion, digital preoperative templating in this
this technique, preoperative planning can be performed
study is an accurate and reproducible process to preo-
anywhere and at any time as long as the images can be
peratively predict the implant size of uncemented THA.
scanned or downloaded directly from the radiographic archive into the Photoshop software. Given its lower cost
Acknowledgements
and higher flexibility compared with commercial orthopaedic
We acknowledge the help from all respondents of this study
software, Photoshop may be therefore an alternative for
and all the other people who generously helped us with this
the preoperative digital templating of THA. Additionally,
study.
the digital preoperative templates can also serve as a permanent data record useful for future THA.
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Heep H, Xu J, Löchteken C, et al. A simple and
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alternative to this would have been the use of the
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Kosashvili Y, Shasha N, Olschewski E, et al. Digital
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Vol. 30, No. 3 P. 150-155
CHINESE MEDICAL SCIENCES JOURNAL ORIGINAL ARTICLE
Accuracy of a Simple Digital Templating in Primary Uncemented Total Hip Arthroplasty△ Hai-bo Si, Yi Zeng, Fei Cao, Fu-xing Pei, and Bin Shen* Department of Orthopaedics, West China Hospital, Sichuan University, Chengdu 610041, China
Key words: arthroplasty; hip; digital templating; preoperative planning; accuracy Objective To introduce a simple preoperative digital templating in uncemented total hip arthroplasty (THA) and to determine its accuracy for preoperative size selection of the prostheses. Methods A prospective study of digital planned THAs was performed on 90 hips with different types of prostheses from August 2013 to Angust 2014. The plastic templates of different types of prostheses were scanned for desired digital templating and the scanned images were then processed to the transparent, digital templates using Photoshop software. We calibrated the scales of the digital templates with the preoperative radiographs, and then selected the right size of the component. The preoperatively digital planned component sizes were compared to the actual sizes used in the operation, as well as the preoperatively traditional planned sizes. Results In either cup or stem templating, no difference was found among the groups with different types of prostheses, and the accuracy of digital templating was statistically higher than traditional templating. In cup templating, digital planned and implanted cup sizes were identical in 43.33% of the cases, 78.89% of the cup sizes were predicted within 1 size (± 2mm) and 95.56% were predicted within 2 sizes (±4 mm), all significantly higher than the results of traditional planned sizes (30.00%, P=0.044; 61.11%, P=0.007; 82.22%, P=0.004). The exact femoral stem size was predicted in 40.00% of cases using the digital templating, 84.44% of stem sizes were predicted within 1 size, and 93.33% within 2 sizes, better than using traditional templating (25.56%, P=0.028; 53.33%, P＜0.001; 77.77%, P=0.003). Conclusion This simple digital preoperative templating is an accurate and reproducible process to preoperatively predict the implant size of uncemented THA.
Chin Med Sci J 2015; 30(3):150-155
T
OTAL hip arthroplasty (THA) is one of the most
prostheses, precise preoperative planning has become vital
successful procedures for surgical treatment of a
for successful THA, and more emphasis has been placed on
diseases.1-3
increasing
selecting the accurate implant size to avoid facture with a
number of THAs and the use of uncemented
component too large or subsidence with a component too
variety
of
hip
With
small.4,5 Traditionally, plain radiographs and plastic tem-
Received for publication November 24, 2014.
plates with fixed magnification factors of 115% or 120%
△Supported by the Health Research Program of Ministry of Health
were used to achieve these goals, but the uncontrolled
(201302007).
magnification of the plain radiographs from different
*Corresponding author Tel: 86-13881878767, E-mail: [email protected]
equipment often result in errors in preoperative templating.
Vol. 30, No.3
CHINESE MEDICAL SCIENCES JOURNAL
151
The outcomes of the operation would be affected if the
until the scale of the digital template layer coincide with the
unmatched
radiograph’s scale (Fig. 2A). The digital template image
component
according
to
the
inaccurate
preoperative measurement is used.6-8
was moved and rotated to select the right size of the
Digital radiography is currently replacing traditional
component. Select the acetabular size that matches the
radiography in many hospitals, and digital templating was
contour of the patient’s acetabulum without excessive
proposed as a method to electronically overlay templates
removal of subchondral bone. The medial position of the
from a digital library on clinical radiographs for arthroplasties.9
acetabular template is at the teardrop and the inferior
Combination of digital radiography and digital templating
margin at the level of the obturator foramen (Fig. 2B).
has the potential to eliminate the errors associated with the
Select the femoral size that matches most precisely the
manual manipulation of plastic templates and plain
contour of the proximal canal, restore the horizontal and
radiographs. To date, many studies have evaluated the
vertical offset and fit (Fig. 2C). Template the femur on
accuracy of digital templating using expensive orthopaedic
the lateral view in the similar manner to ascertain
10,11
This prospective study
whether the implant determined on the anteroposterior
introduces a simple digital templating and determines how
radiograph can be inserted without excessive bone
well preoperative size selection of THAs of this digital
removal (Fig. 2D).
software in uncemented THA.
templating correlates with the size actually implanted.
All the digital templating was performed prospectively by the first author, who is familiar with the Photoshop software. In addition, preoperative planning was also performed
MATERIALS AND METHODS
traditionally, using the plain radiographs and plastic templates,
Preparation of digital templating
by the second author.
Plastic templates of Corail, Summit and Tri-lock femoral stem and Pinnacle acetabular cup (DePuy, USA) were used.
Total hip arthroplasty
These template overlays were scanned for desired digital
A total of 90 planned size selections were recorded
templating using a standard tabletop scanner and the
prospectively for selective uncemented THAs and were
scanned images were saved as JPEG (.jpg) files. The
compared with the actual size implanted at surgery and
scanned images were then opened in Photoshop CS6
with traditional preoperative size selections from August
software (Adobe Systems Inc, San Jose, CA, USA), the
2013 to August 2014. Patients underwent a staged or
blank areas were selected by the “Magic Wand tool” and
simultaneous THA used only template for the first hip. The
deleted using the “Delete” key. The measure image, ruler,
90 uncemented THAs were performed by a senior joint
size, and other markers were remained, the “Erase” tool
surgeon (the corresponding author) who has implemented
was used to erase the extra spots when necessary. Finally,
more than 800 THAs successfully using a posterior-lateral
the transparent, digital templates were named (type-size)
approach, the preoperative diagnoses were osteoarthritis
and saved as PNG (.png) files (Fig. 1).
or avascular necrosis of femoral head. All the patients
Preoperative templating
liner and ceramic femoral head (DePuy, USA). Thirty patients
The preoperative digital radiographs of the hips were
received Corail femoral stem (Group A), 30 received Summit
obtained by digital radiography. Care was taken to ensure
femoral stem (Group B), and 30 received Tri-lock femoral
weight bearing radiographs were well centered with the
stem (Group C) (DePuy, USA). The sizes of acetabular cup
coccyx
and femoral stem used in the operation were recorded.
received a Pinnacle cup, high-cross-linked polyethylene
pointing
just
above
the
symphysis
pubis,
symmetrical obturator foramina, and with both feet in 10° to 15° of internal rotation. The digitized radiographs were
Statistical analysis
stored in the hospital image station, and downloaded to our
Statistical analysis was performed with SPSS 18.0 (SPSS,
computer saved as JPEG files.
Inc, Chicago, IL, USA) software by the third author, who
The JPEG images of hip radiograph and the digital
did not participate in planning or surgery. All categorical
templates were imported into Photoshop software. The
variables, such as gender, operative side and the accuracy
preoperative hip radiograph was opened as the initial
of planned sizes analyzed against the final component sizes
image and set as under layer, the digital template image
at surgery, were compared using the Chi-square test.
was then moved and placed on preoperative radiograph,
Continuous variables (age) were expressed as means ±SD,
scaled by the “free transform” tool, with the SHIFT key
and comparisons were employed using 2-sided T-test for
pressed to keep the same aspect ratio and avoid distortion,
paired groups. P<0.05 was considered statistically significant.
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CHINESE MEDICAL SCIENCES JOURNAL
September 2015
Figure 1. Preparation of the transparent, digital templates of Pinnacle acetabular cup (A) and Corail femoral stem (B).
Figure 2. Preoperative digital templating. A. Calibration of the scale of the digital template and the preoperative radiograph layer; B. Digital templating of the acetabular cup size; C. Digital templating of the femoral stem size on the anteroposterior view; D. Digital templating of the femoral stem size on the lateral view.
of the cases in digital templating and 25.56% in traditional
RESULTS
group. The increments of the manufactured Corail, Summit and Tri-lock stem are 1 sizes. 84.44% of stem sizes were
The average age of group C was statistically lower than
predicted within 1 size, and 93.33% within 2 sizes in digital
that of group A (P=0.041, Table 1), but no significant
templating. In comparison, 53.33% within 1 size and
differences in sex and operated side between the groups
77.77% with in 2 sizes, respectively, were predicted in
were found (all P>0.05). The digital and traditional
traditional templating. The accuracy of digital templating
templating results of either cup or stem showed no
for femoral stem size was statistically higher than
difference among group A, B, and C (all P> 0.05, Table 2).
traditional templating (P<0.05, Table 3).
In acetabular cup templating, digital planned and implanted cup sizes were identical in 43.33% of the cases.
Table 1. Characteristics of the included patients
The increments in size of the manufactured Pinnacle cup are 2 mm, a total of 78.89% of cup sizes were predicted within 1 size (± 2mm), and 95.56% were predicted within 2 sizes (±4 mm) in digital templating. Whereas, traditional planned and implanted sizes were identical in 30.00%, within 1 size in 61.11% and within 2 sizes in 82.22%. The accuracy of digital templating for acetabular cup size was
Sex
Side
(M:F)
(L:R)
Groups
n
Age (yrs)
A
30
56.10±12.86
21: 9
15:15
B
30
54.83±12.80
17:13
17:13
14:16
19:11
C
30
*
49.40±10.17
statistically higher than that of traditional templating
Group A received Corail femoral stem, group B received
(P<0.05, Table 3).
summit femoral stem, and group C received Tri-lock femoral
The exact femoral stem size was predicted in 40.00%
stem; *P<0.05 compared with group A.
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153
Table 2. The templating results of the digital and traditional groups with different types of prostheses [n=30, n(%)] Exact Size Groups Cup
Stem
±1 size
±2 sizes
Traditional
Digital
Traditional
Digital
Traditional
Digital
A
10 (33.33)
14 (46.67)
18 (60.00)
24 (80.00)
25 (83.33)
29 (96.67)
B
8 (26.67)
12 (40.00)
18 (60.00)
23 (76.67)
24 (80.00)
28 (93.33)
C
9 (30.00)
13 (43.33)
19 (63.33)
24 (80.00)
25 (83.33)
29 (96.67)
A
8 (26.67)
13 (43.33)
17 (56.67)
26 (86.67)
24 (80.00)
28 (93.33)
B
8 (26.67)
11 (36.67)
15 (50.00)
24 (80.00)
23 (76.67)
27 (90.00)
C
7 (23.33)
12 (40.00)
16 (53.33)
26 (86.67)
23 (76.67)
29 (96.67)
Table 3. The total templating results of the digital and traditional groups [n(%)] Cup
Accuracy
Traditional
Digital
Exact size
27 (30.00)
39 (43.33)
± 1 size
55 (61.11)
± 2 size
74 (82.22)
Stem
P
P
Traditional
Digital
0.044
23 (25.56)
36 (40.00)
0.028
71 (78.89)
0.007
48 (53.33)
76 (84.44)
<0.001
86 (95.56)
0.004
70 (77.77)
84 (93.33)
0.003
accuracy was significantly higher than traditional manual templating.
DISCUSSION
A few studies investigated the manual onlay templating
Preoperative templating is regarded as an essential
of uncemented THA. It has been reported that the cup was
step for successful implantation of the hip prostheses.
accurate in 20%-51% of cases, which increased to 60%-
Traditional templating is mainly based on plastic templates
100% within 1 cup size, and the femoral stem was accurate
and plain radiographs, the plastic templates have a fixed
in 40%-79% of cases, which increased to greater than
magnification of 115% or 120% usually, but the magnification
85%-100% within 1 femoral stem size.12,14-16 More studies
of the plain radiographs from different device is difficult to
have
investigated
digital
templating
in
uncemented
control, and it will result in errors in preoperative templating.6-8
THA.
Furthermore, if the unmatched component according to the
cup had an accuracy of 25%-84%, which was 60%-91%
inaccurate preoperative templating was used, especially by
within 1 size, and more than 90% within 2 sizes. The
inexperienced joint surgeons, intraoperative facture (with
accuracy for the femoral stem was 35%-62% in femoral
too large a component) or postoperative subsidence (with
stem, which was 74%-98% within 1 size, and greater than
too small a component) might occur, and the postoperative
95% within 2 sizes. The et al20 showed a higher accuracy of
rehabilitation would be affected.4,
5
10,12,17-20
They found that templating of the acetabular
The introduction of
cup estimation in digital templating compared with manual
digital radiography is advantageous in preoperative planning
onlay technique, but there were no differences in stem
for THA since it shows good intra- and inter-observer
evaluation. In these studies, Trauma Cad templating system
reliability, as well as provides higher imaging quality
(Orthocrat Ltd, Petach-Tikva, Israel), Orthoview software
through the possibility of image editing and individual
(Meridian Technique Ltd., Southampton, United Kingdom)
referencing.12,
However, the commercial orthopaedic
or Hyper ORTHO software (Rogan-Delft BV, Venendaal,
software is expensive, relies on the digital library and needs
Netherlands) were adopted. These commercial orthopaedic
to design for each application, and whether the digital
software have the disadvantage of depending on the digital
templating using these commercial orthopaedic software is
library, high-cost, and limitations in software design for
superior to manual templating in predicting prosthesis size
each application.
13
is still controversial.10,11 In this study, we prospectively
The application of Photoshop has been reported in
investigated the accuracy of a simple digital templating in
optimizing radiographic images,21 preoperative surgical
estimating the size of the hip prostheses, and found that its
planning,9 and three-dimensional reconstruction of anatomic
154
CHINESE MEDICAL SCIENCES JOURNAL
September 2015
structures based on segmented MR images.22 The techniques
alternative for the existing complex preoperative digital
for image rotation, sizing, and the use of layers in these
templating of THA.
studies are similar to those used in the current study. Using
In conclusion, digital preoperative templating in this
this technique, preoperative planning can be performed
study is an accurate and reproducible process to preo-
anywhere and at any time as long as the images can be
peratively predict the implant size of uncemented THA.
scanned or downloaded directly from the radiographic archive into the Photoshop software. Given its lower cost
Acknowledgements
and higher flexibility compared with commercial orthopaedic
We acknowledge the help from all respondents of this study
software, Photoshop may be therefore an alternative for
and all the other people who generously helped us with this
the preoperative digital templating of THA. Additionally,
study.
the digital preoperative templates can also serve as a permanent data record useful for future THA.
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