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Journal ArticleDOI

4D-SPECT/CT in orthopaedics: a new method of combined quantitative volumetric 3D analysis of SPECT/CT tracer uptake and component position measurements in patients after total knee arthroplasty

22 May 2013-Skeletal Radiology (Springer Berlin Heidelberg)-Vol. 42, Iss: 9, pp 1215-1223

TL;DR: This combined 3D-volumetric standardised method of analysing the location, size and the intensity of SPECT/CT tracer uptake regions (“hotspots”) and the determination of the TKA position was highly reliable and represents a novel promising approach to biomechanics.

AbstractObjective The purpose was to evaluate the intra- and inter-observer reliability of combined quantitative 3D-volumetric single-photon emission computed tomography (SPECT)/CT analysis including size, intensity and localisation of tracer uptake regions and total knee arthroplasty (TKA) position.

Summary (2 min read)

Introduction

  • Single-photon emission computed tomography /CT is becoming an increasingly available diagnostic imaging modality worldwide [1–8].
  • The clinical diagnostic benefits of SPECT/CT for orthopaedic patients such as the combination of functional, structural and mechanical information have been particularly highlighted for patients with problems after total knee arthroplasty (TKA) [4, 8–11] (Figs. 1, 2 and 3).
  • Others used more descriptive methods to characterise areas of altered SPECT tracer uptake [1, 9, 11–13].
  • Such a three-dimensional approach to SPECT data analysis promises a richer source of clinical information and allows quantitative comparison of SPECT/CT measurements across patients [14].
  • Together with the determination of TKA component position in 3D-CT, it represents a novel approach to biomechanics in patients after TKA [15].

Materials and methods

  • Included was a consecutive series of patients undergoing SPECT/CT because of persistent pain after TKA.
  • For tracer uptake analysis (intensity and anatomical distribution pattern) the 3D-reconstructed datasets of the delayed SPECT/CT images were used.
  • The position of the femoral and tibial TKA component was assessed on 3D-CT after reorientation to the mechanical axis.
  • Sample size was estimated according to the reported estimates for reliability studies using intraclass correlation coefficients (ICCs) [17].

Results

  • The absolute measurements of tracer intensity for each anatomical area and the ratios (in relation to the background intensity of the distal femur) of both observers are presented in Tables 1 and 2.
  • The measurements of tracer uptake intensity using this 3D voxel-based analysis showed very good interand intra-observer reliabilities for all regions (tibia, femur and patella).
  • Only the tibial shaft area showed ICCs <0.89.
  • Table 4 compares the areas indicating the maximum tracer uptake when measured by each observer.
  • For measurement of the femoral and tibial component position, there was strong agreement between the readings of the two observers; the ICCs for the orientation of the femoral and tibial components for inter- and intra-observer reliability were >0.84, which is nearly perfect.

Discussion

  • The proposed method of combined quantitative 3D analysis of SPECT tracer uptake and measurements of TKA component position reflects a novel approach to biomechanics in patients after TKA.
  • The most important findings and implications of their present study are threefold:.
  • The maximum uptake value in each anatomical area was almost perfectly reliable.
  • Third, the determination of femoral and tibial TKA component position in 3D-CT was highly reliable.

Conclusions

  • The proposed combined 3D-volumetric standardised method of analysing the location, size and the intensity of SPECT/CT tracer uptake regions (“hotspots”), as well as the determination of TKA component position, is highly reliable.
  • Its clinical value will be further investigated in prospective clinical studies.
  • The authors greatly thank the Gottfried und Julia Bangerter-Rhyner-Stiftung, Berne, Switzerland as well as the Deutsche Arthrose Hilfe e.V, Saarlouis, Germany for supporting their research.
  • The authors declare that they have no conflict of interest.

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SCIENTIFIC ARTICLE
4D-SPECT/CT in orthopaedics: a new method
of combined quantitative volumetric 3D analysis
of SPECT/CT tracer uptake and component position
measurements in patients after total knee arthroplasty
Helmut Rasch & Anna L. Falkowski & Flavio Forrer &
Johann Henckel & Michael T. Hirschmann
Received: 28 February 2013 / Revised: 13 April 2013 / Accepted: 28 April 2013 / Published online: 22 May 2013
#
ISS 2013
Abstract
Objective The purpose was to evaluate the intra- and inter-
observer reliability of combined quantitative 3D-volumetric
single-photon emission computed tomography (SPECT)/CT
analysis including size, intensity and localisation of tracer
uptake regions and total knee arthroplasty (TKA) position.
Materials and methods Tc-99m-HDP-SPECT/CT of 100
knees after TKA were prospectively analysed. The anatomical
areas represented by a previously validated localisatio n scheme
were 3D-volumetrically analysed. The maximum intensity was
recorded for each anatomical area. Ratios between the respec-
tive value and the mid-shaft of the femur as the reference were
calculated. Femoral and tibial TKA position (varusvalgus,
flexionextension, internal rotation external rotation) were
determined on 3D-CT. Two consultant radiologists/nuclear
medicine physicians interpreted the SPECT/CTs twice with a
2-week interval. The inter- and intra-observer reliability was
determined (ICCs). Kappa values were calculated for the area
with the highest tracer uptake between the observers.
Results The measurements of tracer uptake intensity
showed excellent inter- and intra-observer reliabilities for
all regions (tibia, femur and patella). Only the tibial shaft
area showed ICCs <0.89. The kappa values were almost
perfect (0.856, p<0.001; 95 % CI 0.778, 0.922). For
measurements of the TKA position, there was strong
agreement within and between the readings of the two
observers; the ICCs for the orientation of TKA compo-
nents for inter- and intra-observer reliability were nearly
perfect (ICCs >0.84).
Conclusion This combined 3D-volumetric standardised
method of analysing the location, size and the intensity of
SPECT/CT tracer uptake regions (hotspots) and the deter-
mination of the TKA position was highly reliable and repre-
sents a novel promising approach to biomechanics.
Keywords Knee
.
Total knee arthroplasty
.
3D voxel
analysis
.
Intra- and inter-observer reliability
.
SPECT-CT
.
Component position
Introduction
Single-photon emission computed tomography (SPECT)/CT
is becoming an increasingly available diagnostic imaging
modality worldwide [18]. The clinical diagnostic benefits
of SPECT/CT for orthopaedic patients such as the combina-
tion of functional, structural and mechanical information have
been particularly highlighted for patients with problems after
total knee arthroplasty (TKA) [4, 811](Figs.1, 2 and 3).
Hirschmann et al. reported a standardised, validated and
highly reliable anatomical localisation scheme, which they
used to identify typical distribution patterns of areas indi-
cating increased or decreased SPECT/CT tracer intensity
[8]. The analysis of SPECT tracer uptake was performed
using a Likert scale in a semiquantitative manner on 2D
axial, coronal and sagittal slices [ 8]. Others used more
descriptive methods to characterise areas of altered SPECT
tracer uptake [1, 9, 1113].
M. T. Hirschmann (*)
Department of Orthopaedic Surgery and Traumatology,
Kantonsspital Baselland, 4101 Bruderholz, Switzerland
e-mail: Michael_Hirschmann@web.de
H. Rasch
:
A. L. Falkowski
:
F. Forrer
Institute for Radiology and Nuclear Medicine,
Kantonsspital Baselland, 4101 Bruderholz, Switzerland
J. Henckel
Imperial College London, London, UK
Skeletal Radiol (2013) 42:12151223
DOI 10.1007/s00256-013-1643-2

Another limitation of the conventional analysis tech-
niques is that only areas of increased tracer intensity
were considered and lower intensity SPECT values were
neglected [ 14]. In our experience the distribution pattern
of SPECT tracer uptake is at least equally as important
for accurate and correct establishment of the diagnosis
[4, 14].
Striving for improvement of SPECT data analysis we
have introduced a novel method of 3D-volumetric quan-
tification, normalisation and thresholding of SPECT data
[14]. Such a three-dimensional approach to SPECT data
analysis promises a richer source of clinical information
and allows quantitative comparison of SPECT/CT mea-
surements across patients [14]. Together with the deter-
mination of TKA component position in 3D-CT, it
represents a novel approach to biomechanics in patients
after TKA [15].
The primary purpose of this study was t o e valuate the
inter- and intra-observer reliability of a standardised ap-
proach to combined quantitative 3D-volumetric SPECT/
CT analysis including assessment of the size, the inten-
sity and the localisation of enhanced tracer uptake re-
gions and determination of the TKA component position
on 3D-CT. With the introduction of this analysis tool we
aim to improve the process of establishing the diagnosis
in patients with painful TKA. SPECT/CT could then be
considered a screening tool and outcome measure in
clinical trials.
Materials and methods
A total of 100 knees (male:female = 34:66, mean
age ± standard deviation 70±11 years; right:left = 53:47)
after total knee arthroplasty (TKA) that underwent Tc-99m-
HDP-SPECT/CT were prospectively collected. Included
was a consecutive series of patients undergoing
SPECT/CT because of persistent pain after TKA. Patients
who had previously undergone a revision TKA were exclud-
ed. The mean time from primary TKA to the date of
Fig. 1 3D-voxel based
single-photon emission
computed tomography
(SPECT) tracer uptake analysis
(OrthoImagingSolutions,
London, UK): definition of a
sample volume in the SPECT
data set (red box, red arrow)
and 3D-voxel-based
quantification of absolute
maximum, minimum and
mean uptake values in different
anatomical areas
1216 Skeletal Radiol (2013) 42:12151223

SPECT/CT imaging was 48±48 months. The study was
approved by our local ethics committee.
99mTc-HDP-SPECT/CT
All patients received a commercial 700 MBq (18.92 mCi) Tc-
99m-HDP injection (Malinckrodt, Wollerau, Switzerland).
Tc-99m-HPD-SPECT/CT was performed using a hybrid sys-
tem (Symbia T16; Siemens, Erlangen, Germany), which con-
sists of dual head camera with a pair of low-energy, high-
resolution collimators and an integrated full diagnostic CT
with 160.75-mm collimation. Planar scintigraphic images
were taken in the perfusion phase (immediately after injec-
tion), the blood pool phase (2 to 5 min after injection) and the
delayed metabolic phase (23 h after injection) followed by
the SPECT/CT. For SPECT acquisition we used the step and
shoot mode (32 steps/25 s) with a matrix of 128×128. The CT
protocol was modified according to the Imperial Knee
Protocol, which is a low -dose CT protocol that includes
high-resolution 0.75-mm slices of the knee and 3-mm slices
of the hip and ankle joints [16]. This protocol allows accurate
determination of mechanical alignment and TKA component
positions in 3D.
For tracer uptake analysis (intensity and anatomical dis-
tribution pattern) the 3D-reconstructed datasets of the de-
layed SPECT/CT images were used. The anatomical areas
represented by a previously validated localisation scheme
were 3D-volumetrically measured in terms of SPECT/CT
tracer uptake values [8, 14]. This localisation scheme for
patients after primary TKA consists of 9 tibial, 9 femoral
and 4 patellar regions around TKA components to accurate-
ly map tracer uptake activity [ 4 , 8]. The maximum intensity
values were recorded for each anatomical area. In addition,
ratios between the respective value in the measured area and
the background tracer activity measured at the proximal end
of the femoral field of view (FOV) were calculated.
Fig. 2 Determination of tibial and femoral total knee arthroplasty
(TKA) component position (varusvalgus, flexionextension, internal
rotationexternal rotation) on 3D-CT using customised software after
reorientation in relation to the mechanical axis and definition of ana-
tomical landmarks on the bone surface (OrthoImagingSolutions,
London, UK)
Skeletal Radiol (2013) 42:12151223 1217

Measurements of TKA component position in 3D-CT
The position of the femoral and tibial TKA component was
assessed on 3D-CT after reorientation to the mechanical axis.
The sagittal (flexionextension), coronal (varusvalgus) and
rotational alignment (internal rotation external rotation) of
the femoral and tibial TKA components were determined on
3D-reconstructed CT images using customised software
(OrthoImagingSolutions, London, UK). The rotation of the
femoral component (femoral posterior component axis) was
measured in relation to the anatomical transepicondylar axis.
The rotation of the tibial component (tibial posterior compo-
nent axis) was measured in relation to the posterior tibial
plateau axis. One consultant radiologist/nuclear medicine spe-
cialist and one radiologist interpreted the SPECT/CTs for
tracer uptake and component analysis twice with a 2-week
interval between interpretations in a random order. Both were
blinded to results from previous observations.
All data were analysed by an independent professional
statistician using SPSS version 17.0 (SPSS, Chicago, IL,
USA.). Sample size was estimated according to the reported
estimates for reliability studies using intraclass correl ation
coefficients (ICCs) [17].
The inter- and intra-observer reliability of the intensity
and distribution analysis of SPECT/CT were determined by
calculating the intraclass correlation coefficients (ICC). An
ICC value of 1 indicated perfect reliability, 0.81 to 1 very
good reliability and 0.61 to 0.80 good reliability [17].
In addition, an inter-observer reliability analysis using the
Kappa statistic was performed to determine consistency
on the area with the highest tracer uptake. Kappa values
of < 0 represent poor, 0.00.20 slight, 0.210.40 fair, 0.41
0.60 moderate, 0.610.80 substantial and 0.811.00 an
almost perfect agreement [18].
Results
All hotspots (areas with increased tracer uptake) were pres-
ent in the localisation scheme and could be located to
Fig. 3 The previously validated SPECT/CT scheme used for
localisation of the Tc-99m HDP tracer activity in patients with painful
knees after primary total knee arthroplasty. F femur, T tibia, P patella, 1
medial, 2 lateral, 3 central around stem, a anterior, p posterior, i
inferior, s superior, shaft, tip and tubercle. Reprinted with permission.
Publication can be found at www.springerlink.com [11]
1218 Skeletal Radiol (2013) 42:12151223

Table 1 Absolute tracer intensity values measured for each anatomical area and both observers
Observer 1 Observer 2 Both
Mean Standard deviation Median Minimum Maximum Mean Standard deviation Median Minimum Maximum Mean Standard deviation Median Minimum Maximum
f shaft 196.9 113.8 180 40 722 178.5 115.4 150 27 722 187.9 111.5 166 34 722
f med sa 472.4 389.1 381 47 2,550 442.8 383.8 364 38 2,550 457.7 384.3 379 43 2,550
f med sp 561.2 505.4 438 57 3,730 557.6 509.4 427 57 3,730 559.5 506.6 427 57 3,730
f med ia 441.9 308.7 360 31 1,652 427.3 303.1 353 30 1,652 434.8 303.2 367 31 1,652
f med ip 514.9 379.2 435 36 1,892 513.4 381.4 429 41 1,892 514.2 379.7 427 40 1,892
f lat sa 580.1 522.2 432 65 3,462 527.2 473.2 412 65 3,389 553.8 491.2 423 65 3,426
f lat sp 605.8 530.6 531 74 3,465 602.4 527.6 531 78 3,465 604.2 527.6 531 76 3,465
f lat ia 492.3 419.1 382 70 2,397 480.1 418.3 377 70 2,397 486.3 416.8 375 70 2,397
f lat ip 569.1 406.3 433 95 2,365 563.2 407.7 448 95 2,365 566.2 406 430 95 2,365
t med a 511.3 285.1 470 54 1,581 496.9 275.7 479 54 1,581 504.2 278.2 463 54 1,581
t med p 569.2 315.8 525 71 1,439 568.7 319.7 520 74 1,368 569 316.1 520 74 1,404
t lat a 483.3 275.3 460 77 1,496 488.5 277.2 457 77 1,496 485.9 274.3 460 77 1,496
t lat p 519.2 299.3 452 54 1,350 527.9 298.8 475 54 1,350 523.6 292.7 467 54 1,350
t stem 459.4 269.4 408 48 1,383 490.1 280.9 434 49 1,339 474.9 271.9 422 49 1,361
t tip 279.7 186.8 237 37 1,202 266.8 173.2 226 55 1,113 273.4 177.8 232 48 1,158
t shaft 214.2 113.5 189 46 552 161.1 82.8 146 34 378 187.9 93.8 174 41 428
p med s 591.8 386.5 512 77 1,852 597.4 398.4 502 77 1,852 594.7 390.7 508 77 1,852
p med i 527.7 333.2 500 61 1,715 521.6 347.9 483 61 1,775 524.8 336.9 490 61 1,715
p lat s 622.2 419.4 519 97 1,845 603.1 405.3 493 101 1,841 612.8 409.3 503 100 1,843
p lat i 566.6 394.1 463 103 1,602 552.8 396.3 440 98 1,760 559.9 390.7 442 103 1,602
p total 713.2 446.3 620 108 1,852 703.1 447.1 620 108 1,852 708.2 445.4 639 108 1,852
f femur, t tibia, p patella, sa superioranterior, sp superiorposterior, ia inferioranterior, ip inferiorposterior, med medial, lat lateral
Skeletal Radiol (2013) 42:12151223 1219

Figures (6)
Citations
More filters

Journal ArticleDOI
TL;DR: An overview of SPECT/CT imaging of the extremities with a focus on the hand and wrist, knee and foot, and for evaluation of patients after joint arthroplasty is given.
Abstract: Today, SPECT/CT is increasingly used and available in the majority of larger nuclear medicine departments. Several applications of SPECT/CT as a supplement to or replacement for traditional conventional bone scintigraphy have been established in recent years. SPECT/CT of the upper and lower extremities is valuable in many conditions with abnormal bone turnover due to trauma, inflammation, infection, degeneration or tumour. SPECT/CT is often used in patients if conventional radiographs are insufficient, if MR image quality is impaired due to metal implants or in patients with contraindications to MR. In complex joints such as those in the foot and wrist, SPECT/CT provides exact anatomical correlation of pathological uptake. In many cases SPECT increases the sensitivity and CT the specificity of the study, increasing confidence in the final diagnosis compared to planar images alone. The CT protocol should be adapted to the clinical question and may vary from very low-dose (e.g. attenuation correction only), to low-dose for anatomical correlation, to normal-dose protocols enabling precise anatomical resolution. The aim of this review is to give an overview of SPECT/CT imaging of the extremities with a focus on the hand and wrist, knee and foot, and for evaluation of patients after joint arthroplasty.

69 citations


Cites background from "4D-SPECT/CT in orthopaedics: a new ..."

  • ...A novel four-dimensional SPECT/CT approach correlates tracer uptake and joint replacement component positioning in patients after total knee arthroplasty, showing excellent inter- and intraobserver reliabilities, and might therefore be the evaluation standard of the future [42, 43]....

    [...]


Journal ArticleDOI
TL;DR: The diagnostic benefits of SPECT/CT in patients after TKA have been proven and typical pathology-related BTU patterns were identified, which will improve reporting quality.
Abstract: Purpose Bone single photon emission computed tomography (SPECT)/CT is considered as beneficial in unhappy patients with pain, stiffness or swelling after total knee arthroplasty (TKA). The purpose of this study was to identify typical patterns of bone tracer uptake (BTU), distribution and intensity values in patients after TKA. The above findings were correlated with the type and fixation of TKA, the time from TKA and intraoperative findings at revision surgery.

44 citations


Cites background or methods from "4D-SPECT/CT in orthopaedics: a new ..."

  • ...They reported near perfect inter- and intra-observer reliability for their proposed standardized SPECT/CT algorithm including a localization scheme, intensity value and 3-D prosthetic component analysis [3, 6]....

    [...]

  • ...In previous studies this measurement method was shown to be highly accurate [2, 3, 23, 24]....

    [...]

  • ...highlighted the clinical value of a standardized diagnostic algorithm including SPECT/CT in patients with problems after TKA [3]....

    [...]

  • ...85, which is considered to be a near perfect reliability [3]....

    [...]

  • ...3 Measurement of femoral and tibial TKA component positions (varus-valgus, flexion-extension, internal rotation-external rotation) in 3-D reconstructed CT images using a customized software [3]...

    [...]


Journal ArticleDOI
TL;DR: A significant correlation was found between neutral limb alignment and higher KSS only in patients with preoperative non-varus alignment, suggesting that one should aim for a more individualized, alignment target based on the individual knee morphotype.
Abstract: The optimal coronal alignment is still under debate. However, in most of the studies, alignment was only assessed using radiographs, which are not accurate enough for assessment of tibial and femoral TKA position. The primary purpose of this study was to assess the relationship between coronal TKA alignment using 3D-reconstructed CTs and clinical outcome in patients with preoperative varus in comparison with patients with natural or valgus deformity. It was the hypothesis that neutral limb alignment shows a better outcome after TKA. Prospectively collected data of 38 patients were included. The clinical and radiological follow-up was 24 months. The patients were grouped into two groups with regard to their preoperative limb alignment. Group A (varus) consisted of 21 patients with preoperative varus of 3° or more, while group B (non-varus) consisted of 17 patients with neutral (− 3 + 3) or valgus alignment (> + 3). For assessment of TKA component position and orientation, 3D-reconstructed CT was used. The measurements of the deviation from the whole limb mechanical axis (HKA angle) and the joint line alignment in the femoral (mLDFA) and the tibial side (MPTA) were assessed in the preoperative leg as well as during follow-up after TKA. For clinical outcome assessment, the Knee Society Score (KSS) was used at 1 and 2 years postoperatively. Correlation between KSS score and each variable was done using a linear and quadratic regression model (p < 0.05). The mean postoperative HKA angle was − 1.3 (varus) in the varus group and + 1.4 (valgus) in the non-varus group. Overall, significant correlations between the preoperative and postoperative alignments were found. In the preoperatively non-varus group, a highly significant correlation was found between neutral limb alignment (HKA = 0° ± 3°) and higher KSS (r 2 = 0.74, p = 0.00). In the varus group, no correlation was found between the postoperative whole limb alignment and the components’ position in the coronal plane to KSS score. A significant correlation was found between neutral limb alignment and higher KSS only in patients with preoperative non-varus alignment. The concept of constitutional varus alignment is still under debate. Moreover, it appears that one should aim for a more individualized, alignment target based on the individual knee morphotype. Diagnostic study, Level II.

40 citations


Cites methods from "4D-SPECT/CT in orthopaedics: a new ..."

  • ...The coronal (varus–valgus) alignment was determined with reference to the mechanical axis, according to different anatomical landmarks which have been previously proven to be available and reliable [34]....

    [...]


Journal ArticleDOI
TL;DR: In patients with medial compartment, overloading due to varus malalignment HTO led to a significant decrease in BTU in the medial joint compartments, and SPECT/CT could be used for assessment of adequate correction and healing after HTO.
Abstract: The purpose was to prospectively evaluate the outcome, in particular the SPECT/CT bone tracer uptake (BTU) after high tibial osteotomy (HTO) due to symptomatic varus malalignment. It was the hypothesis that the BTU after HTO decreases in the medial compartment, clinical outcome and the degree of correction correlates with BTU and asymptomatic patients after HTO reveals a significantly decreased BTU in the medial subchondral areas. Twenty-two consecutive patients with 23 knees undergoing medial opening-wedge HTO for medial compartment overloading were assessed pre- and postoperatively (12 and/or 24 months) using Tc-99m-HDP-SPECT/CT including our 4D-SPECT/CT protocol. BTU was quantified and localized to specific biomechanically relevant joint areas. Maximum absolute and relative values (mean ± standard deviation, median and range) for each area were recorded. Pre- and postoperative mechanical alignment was measured. At 24 months after HTO, the WOMAC score was used. A significant decrease of BTU in the medial subchondral zones after HTO was found (preoperatively to 12 and 24 months postoperatively, p < 0.01). BTU normalized in all asymptomatic patients within 24 months. This decrease was partly seen in the lateral compartments, but significantly higher in the medial compartments (p < 0.0001). A significant increase of the BTU was noted in zones directly adjacent to the plate or within the osteotomy zone (p < 0.01). Decreased BTU was observed in osteotomy zones at 24 months postoperatively following higher uptake values at 12 months postoperatively. The average valgus correction of the tibiofemoral angle was 5.9° ± 2.8°. Less stiffness correlated significantly with a higher decrease in BTU (p < 0.05). Higher postoperative BTU significantly correlated with more pain (p < 0.05). No statistical significant associations between BTU and alignment correction were found. In patients with medial compartment, overloading due to varus malalignment HTO led to a significant decrease in BTU in the medial joint compartments. SPECT/CT BTU patterns and intensity in these patients pre- to 12 and 24 months postoperatively were seen. These correlated significantly with pain and stiffness. Hence, SPECT/CT could be used for assessment of adequate correction and healing after HTO. SPECT/CT could be further used to identify the optimal individualized correction for each patient and clinical scenario. Diagnostic prospective study, Level II.

32 citations


Cites methods from "4D-SPECT/CT in orthopaedics: a new ..."

  • ...99mTc-HDP-SPECT/CT was performed preoperatively, 12 and/or 24 months after HTO using our previously published 4D-SPECT/CT protocol [29]....

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Journal ArticleDOI
TL;DR: The postoperative outcome was not influenced by coronal TKA component position as well as the whole leg alignment and the findings challenge the current target of neutral coronal alignment and point towards a more individualized mechanical alignment target.
Abstract: The aim of this study was to evaluate femoral and tibial as well as whole leg coronal TKA alignment using 3D-reconstructed CTs and to assess the relationship of coronal TKA alignment and clinical outcome in a large prospective series of patients. It was hypothesized that a coronal deviation of TKA position and leg alignment from the mechanical axis is correlated with poorer patients’ outcome after TKA. A total of 81 consecutive patients who underwent primary TKA were prospectively included. The patient’s demographics such as age, gender and time from primary TKA were noted. All patients underwent clinical and radiological examination including standardized radiographs (anteroposterior and lateral weight-bearing, patellar skyline view) and CT as part of their postoperative follow-up. For assessment of TKA component position and orientation 3D-reconstructed CT was used. For clinical outcome scoring the Knee Society Score (KSS) was used at 1 and 2 years postoperatively. Linear and quadratic regression models were used to test for correlations between alignment variables and KSS (p < .05). The mean Knee Society Score was 181 ± 28 (range 52–200) 2 years postoperatively, while 78% of the patients were completely pain free and 22% had some persisting pain interfering with their daily activities. The mean mechanical whole limb alignment (HKA angle), femoral component alignment and tibial component alignment were 0°, 0.1° and −0.7°, respectively. The component position parameters, as well as the whole limb alignment measurements, did not show any statistically significant correlation with the KSS, after 1 and 2 years postoperatively. In this prospective study, using 3D-CT to measure the component position, the postoperative outcome was not influenced by coronal TKA component position as well as the whole leg alignment. The findings challenge the current target of neutral coronal alignment and point towards a more individualized mechanical alignment target. Prognostic study, Level I.

32 citations


Cites background or methods from "4D-SPECT/CT in orthopaedics: a new ..."

  • ...The sagittal (flexion–extension), coronal (varus–valgus) and rotational alignment (internal rotation–external rotation) were determined with reference to the mechanical axis, according to different anatomic landmarks which have been previously proven to be available and reliable [24]....

    [...]

  • ...75-mm slices of the knee and 3-mm slices of the hip and ankle joints [24]....

    [...]


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Journal ArticleDOI
TL;DR: 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components in a poorly functioning TKR with concerns over component positioning, and are recommend 3D-CT as the investigation of choice.
Abstract: We studied the intra- and interobserver reliability of measurements of the position of the components after total knee replacement (TKR) using a combination of radiographs and axial two-dimensional (2D) and three-dimensional (3D) reconstructed CT images to identify which method is best for this purpose. A total of 30 knees after primary TKR were assessed by two independent observers (an orthopaedic surgeon and a radiologist) using radiographs and CT scans. Plain radiographs were highly reliable at measuring the tibial slope, but showed wide variability for all other measurements; 2D-CT also showed wide variability. 3D-CT was highly reliable, even when measuring rotation of the femoral components, and significantly better than 2D-CT. Interobserver variability in the measurements on radiographs were good (intraclass correlation coefficient (ICC) 0.65 to 0.82), but rotational measurements on 2D-CT were poor (ICC 0.29). On 3D-CT they were near perfect (ICC 0.89 to 0.99), and significantly more reliable than 2D-CT (p < 0.001). 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components. Rotational measurements in particular should be performed on 3D-reconstructed CT images. When faced with a poorly functioning TKR with concerns over component positioning, we recommend 3D-CT as the investigation of choice.

160 citations


"4D-SPECT/CT in orthopaedics: a new ..." refers background in this paper

  • ...Hence, most authors used axial 2D-CT slices for measurement of component position, although it has been shown that these measurements are very variable and less reliable [15]....

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  • ...Together with the determination of TKA component position in 3D-CT, it represents a novel approach to biomechanics in patients after TKA [15]....

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Journal ArticleDOI
TL;DR: SPECT-CT had significantly higher interobserver agreement, especially when evaluating the naviculocuneiform and tarsometatarsal joints, which is useful in localising active arthritis especially in areas where the number and configuration of joints are complex.
Abstract: The precise localisation of osteoarthritic changes is crucial for selective surgical treatment. Single photon-emission CT-CT (SPECT-CT) combines both morphological and biological information. We hypothesised that SPECT-CT increased the intra- and interobserver reliability to localise increased uptake compared with traditional evaluation of CT and bone scanning together. We evaluated 20 consecutive patients with pain of uncertain origin in the foot and ankle by radiography and SPECT-CT, available as fused SPECT-CT, and by separate bone scanning and CT. Five observers assessed the presence or absence of arthritis. The images were blinded and randomly ordered. They were evaluated twice at an interval of six weeks. Kappa and multirater kappa values were calculated. The mean intraobserver reliability for SPECT-CT was excellent (kappa = 0.86; 95% CI 0.81 to 0.88) and significantly higher than that for CT and bone scanning together. SPECT-CT had significantly higher interobserver agreement, especially when evaluating the naviculocuneiform and tarsometatarsal joints. SPECT-CT is useful in localising active arthritis especially in areas where the number and configuration of joints are complex.

132 citations


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Frequently Asked Questions (2)
Q1. What are the contributions mentioned in the paper "4d-spect/ct in orthopaedics: a new method of combined quantitative volumetric 3d analysis of spect/ct tracer uptake and component position measurements in patients after total knee arthroplasty" ?

Hirschmann et al. this paper evaluated the intraand interobserver reliability of combined quantitative 3D-volumetric single-photon emission computed tomography ( SPECT ) /CT analysis including size, intensity and localisation of tracer uptake regions and total knee arthroplasty ( TKA ) position. 

Its clinical value will be further investigated in prospective clinical studies.