Comparison of Two Scaling Methods in Preoperative Digital Templating of Total Hip Replacement

Leung, Kin-Ho Leo; Mak, Joanna; Lee, On-Bong; Tsang, W L; Khoo, Jls

doi:10.1016/j.jotr.2014.03.002

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Within the literature there is a preference for the use of fixed MF. 6,10,12,[17][18][19] However our results suggest that fixed MF values of 110-120% could be too low for accurate templating. To our knowledge, studies that prefer the use of a fixed MF have neglected to mention the effect of patient body habitus.…”

Section: Discussionmentioning

confidence: 66%

“…There is still debate as to which digital templating technique is most reliable and accurate in clinical practice. Some clinical centres prefer the use of a fixed MF, 6 , 10 , 12 , 17 , 18 as it can provide consistent templating results that are less dependent on radiographic positioning. This method was also used in traditional acetate templating, with a typical assumed MF of 110 to 120%.…”

Section: Introductionmentioning

confidence: 99%

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Pre‐operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

Holliday

Steward

2021

J of Medical Radiation Sci

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Introduction: Pre-operative templating using digital radiography is an effective method of planning for total hip arthroplasty (THA) and requires a generalised fixed magnification factor (MF) or external calibration markers (ECM). The effect on image magnification when changing source-to-image distance (SID), object-to-image distance (OID) and different imaging conditions is not well described. This study aims to quantify the range of effects manipulation of radiographic parameters can have on image magnification across different body habitus and imaging conditions. Methods: A simple phantom study was performed. A 25 mm ECM was placed at eight different OID values along the anterior-posterior phantom plane at three different SID values and imaging conditions, and X-rays were obtained. On each radiograph, the ECM was measured using a line calliper tool by three radiographers and recorded. The MF was calculated and recorded. Results: The smallest observed image MF was 1.16, for an 8 cm OID, 120 cm SID with the ECM placed within the central ray and the X-ray detector in bucky underneath the X-ray table. The largest image MF was 1.40 for a 15 cm OID, 100 cm SID with the X-ray detector placed underneath an emergency department imaging trolley. Conclusions: Digital pre-operative templating for THA relies on accurate radiographic positioning and is dependent of the patient body habitus, radiographic parameters and imaging conditions selected by the radiographer. The use of appropriately positioned ECMsplaced medially between the patient's internally rotated legs at the level of the greater trochanter, lowers the potential for magnification inaccuracies.

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Section: Discussionmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Pre‐operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

Holliday

Steward

2021

J of Medical Radiation Sci

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“…These imperfections in marker placements introduce 6% error in radiographic magnification with range from -5% to 15% as shown by Archibeck et al, 2016 [ 4 ]. Also Leung et al, 2015 [ 19 ] and Franken et al, 2010 [ 6 ] report error estimated using magnification markers to be 7% and 2.5%, respectively. The studies of Archibeck et al, 2016 [ 4 ], Leung et al, 2015 [ 19 ] and Franken et al, 2010 [ 6 ] also show that taking a fixed value of magnification will reduce magnification error to less than 2% in all studies.…”

Section: Discussionmentioning

confidence: 99%

Magnification of digital hip radiographs differs between clinical workplaces

et al. 2017

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Preoperative planning for total hip arthroplasty includes templating on anteroposterior radiographs. It is necessary to consider radiographic magnification in order to scale templates accurately. Studies dealing with hip templating report different values of radiographic magnification. It is not clear if the observed difference in magnification between the studies is caused by variability in studied groups, methodology or instrumentation. We hypothesize that there is a difference in magnification between clinical workplaces. Within this study, radiographic magnification was estimated on 337 radiographs of patients after total hip surgery from five orthopaedic departments in the Czech Republic. Magnification was determined for each patient as a ratio between diameter of implanted femoral head measured on radiogram and its true size. One-way ANOVA revealed significant differences in magnification between workplaces (F(4,332) = 132, p≤0.001). These results suggest that radiographic magnification depends on the workplace where it is taken or more precisely on radiographic device. It indicates potential limits in generalizability of results of studies dealing with preoperative planning accuracy to other institutions.

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Reliably calibrating X-ray images required for preoperative planning of THA using a device-adapted magnification factor

Brüggemann,

Paulsen,

Oppedal

et al. 2024

PLoS ONE

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Background and aim Calibrated pelvic X-ray images are needed in the preoperative planning of total hip arthroplasty (THA) to predict component sizes. Errors and mismatch in the size of one or more components are reported, which can lead to clinically relevant complications. Our aim is to investigate whether we can solve the fundamental problem of X-ray calibration and whether traditional X-ray still has a place in preoperative planning despite improved radiological alternatives. Methods Based on geometric and radiographic principles, we estimate that the magnification factor is adapted to the X-ray device and depends strongly on the source-image distance of the device. We analyse the errors of the various calibration methods and investigate which narrow range can be expected to show that the center of rotation is sufficiently accurate. Based on the results of several CT-scans we defined an adapted magnification factor and validated the degree of measurement accuracy. Results The true magnification of objects on X-ray images depends mainly on the device settings. Stem size prediction is possible to a limited extent, with an error margin of 4.3%. Components can be predicted with a safety margin of one size up and down as with CT or 3D images. The prerequisite is that the source-image distance is greater than or equal to 120 cm, the table-image distance is known, and the object-image distance is estimated according to the patient’s BMI. We defined a device-adapted magnification factor that simplifies the templating routine and can be used to obtain the most reliable preoperative dimensional measurements that can be expected from X-ray images. We found the error margin of the magnification factor with the highest degrees of prediction and precision. Conclusion Preoperative planning is reliable and reproducible using X-ray images if calibration is performed with the device-adapted magnification factor suggested in this paper.

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Comparison of Two Scaling Methods in Preoperative Digital Templating of Total Hip Replacement

Cited by 4 publications

References 12 publications

Pre‐operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

Pre‐operative templating for total hip arthroplasty: How does radiographic technique and calibration marker placement affect image magnification?

Magnification of digital hip radiographs differs between clinical workplaces

Reliably calibrating X-ray images required for preoperative planning of THA using a device-adapted magnification factor

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