Comparison of Techniques for Correction of Magnification of Pelvic X-rays for Hip Surgery Planning

Kootstra, Johan; Hosman, Anton H.; Gerritsma, Carina L. E.; Diercks, Ron L.

doi:10.1007/s10278-006-1042-5

Cited by 9 publications

(9 citation statements)

References 7 publications

(1 reference statement)

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“…The double marker is extremely accurate, and our results are comparable with the best reported elsewhere in the literature. 2,4,13 The median error was only 1.1%. In a patient with an acetabular diameter of 50 mm, the median measurement error when templating for an uncemented acetabular component would be 0.55 mm.…”

Section: Fig 5amentioning

confidence: 90%

“…This magnification is generally determined using a single scale marker (such as a disc or sphere) of known dimensions, positioned in the same coronal plane as the hip joints. Although there are reports [1][2][3][4] suggesting that such markers may permit highly accurate calculation of magnification, this has not been our experience. In our department it has been standard practice to include such a scale marker on the pre-operative radiograph of all patients presenting for a primary hip replacement.…”

mentioning

confidence: 81%

“…In order to locate this plane a number of techniques can be used, including palpation of the greater trochanter with internal rotation of the hips, and measurement of abdominal girth. 4 There is no question that these single markers are accurate if placed correctly. It is crucial to recognise, however, that the good results reported in the literature are only obtained where the marker was positioned very carefully by a limited number of trained individuals making every effort to be as accurate as possible.…”

Section: Fig 5amentioning

confidence: 99%

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A novel method of accurately calculating the radiological magnification of the hip

King

Makrides

Gill

et al. 2009

The Journal of Bone and Joint Surgery. British volume

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We have developed a novel method of calculating the radiological magnification of the hip using two separate radio-opaque markers. We recruited 74 patients undergoing radiological assessment following total hip replacement. Both the new double marker and a conventional single marker were used by the radiographer at the time of x-ray. The predicted magnification according to each marker was calculated, as was the true radiological magnification of the components. The correlation between true and predicted magnification was good using the double marker (r = 0.90, n = 74, p < 0.001), but only moderate for the single marker (r = 0.50, n = 63, p < 0.001). The median error was significantly less for the double marker than for the single (1.1% vs 4.8%, p < 0.001). The double marker method demonstrated excellent validity (intraclass correlation coefficient = 0.89), in contrast to the single marker (0.32). The double marker method appears to be superior to the single marker method when used in the clinical environment.

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Section: Fig 5amentioning

confidence: 90%

mentioning

confidence: 81%

Section: Fig 5amentioning

confidence: 99%

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A novel method of accurately calculating the radiological magnification of the hip

King

Makrides

Gill

et al. 2009

The Journal of Bone and Joint Surgery. British volume

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“…Franken et al showed a mean error of 2.04%, with a maximum difference of 6.46%. The et al showed an error of magnification of only 1.5% whilst Wimsey et al were even more accurate in their study, with an average magnification difference of only 1.1% [9,18]. However, two other similar studies using the implanted femoral head have both shown magnification error to consistently near 6%, which suggests despite a standardized radiological protocol, scaling using an ECM has inherent consistent magnification error of 6% [13,19].…”

Section: Discussionmentioning

confidence: 83%

Digital magnification error when templating total hip replacement?

Zhang¹,

Wyatt²,

Anderson³

2018

Hong Kong J Orthop Res

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Background: Digital templating has become an accepted method of pre-operative planning for total hip replacement (THR). Templating software permits digital templating in a complete digital environment. Accurate templating requires knowledge of the true magnification of the radiograph. Aims and objectives: The aim of this study was to compare the measured magnification factor from using an external calibration marker (ECM) in a standardized radiology protocol, to the true magnification derived from using a prosthetic femoral head of known diameter. Materials and Methods: All patients awaiting staged bilateral THR between 2012 and 2017 were identified. Their radiographs were reviewed, and included in the study if an ECM was present with THR prosthesis in situ. The radiographs were assessed for scaling using two methods, a built-in software method using the ECM, and a manual method, using the implanted femoral head. Magnification factor derived from both methods were compared. Statistics: Statistical analysis was performed using paired Student's t-test for matched samples. Results: A total of 64 radiographs were included. The two methods of scaling produced consistently different magnification factors. Using the ECM, the mean measured magnification was 113.9% (SD 5.4%). The mean true magnification using the implanted femoral head was 119.6% (SD 2.1%). The mean difference was 6.9% (SD 5.7%, range of -18% to 17.1%, p<0.05). Conclusion: In conclusion, a single external calibration marker will have significant error. In clinical practice, the ECM consistently underestimated the magnification of templating radiographs. In patients with an implanted hip replacement, we recommend using the femoral head prosthesis for radiograph scaling.

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“…Similar results have been observed in the study of Archibeck et al (2016) [24] who showed that BMI accounted for a signi cant amount of variability in the measured magni cation both for internal and external marker. However, Boese et al ( 2015) [17] and The et al (2007) [16] observed weak correlation between hip radiographic magni cation and BMI. Study using a double marker method by King et al (2009) [25] also showed a weak correlation between BMI and magni cation.…”

Section: Discussionmentioning

confidence: 99%

The hip radiographic magnification correlates with patient’s BMI

Hornová

Hrubina

Šťastný

et al. 2021

Preprint

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Objective. Obese patients have a higher prevalence of total hip arthroplasty (THA) and they are likely to experience a higher rate of pre-operative and post-operative complications. Pre-operative templating is a standard method of THA planning aiming to minimize the risk of complications. The accuracy of pre-operative templating depends on the knowledge of radiographic magnification factor. Whether and to what extent obesity affects radiographic magnification is not well described in literature. The purpose of this study was to determine whether obesity type affects hip radiographic magnification and quantify the relationship between the obesity measured and change in radiographic magnification. Materials and Methods. Digital radiographs of 303 patients who underwent THA were taken from clinical archives. The size of implanted femoral head was taken as an internal calibration marker to estimate hip radiographic magnification. Patients were stratified into obesity categories by body mass index (BMI). Patients’ mass, BMI, and body surface area (BSA) were studied as predictors of hip magnification. Results. There is a significant effect of obesity type on hip radiographic magnification (one-way ANOVA, p<0.001). The radiographic magnification correlates with patients’ mass (r=0.443, p<0.001), BMI (r=0.450, p<0.001) and BSA (r=0.443, p<0.001). For every 17 kg increase in patients’ mass, 5 kg/m2 increase in the BMI and for every 0.27 m2 in the BSA there is a 1 percent increase in the hip radiographic magnification. The increase in hip radiographic magnification with mass, BMI, and BSA is higher in females than in males. Conclusion. BMI could be used to estimate the increase in hip radiographic magnification due to obesity by adding 1% of magnification on average for each subsequent BMI category.

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Comparison of Techniques for Correction of Magnification of Pelvic X-rays for Hip Surgery Planning

Cited by 9 publications

References 7 publications

A novel method of accurately calculating the radiological magnification of the hip

A novel method of accurately calculating the radiological magnification of the hip

Digital magnification error when templating total hip replacement?

The hip radiographic magnification correlates with patient’s BMI

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