Radiographic Reference Points Are Inaccurate With and Without a True Lateral Radiograph

Ziegler, Connor G.; Fulkerson, John P.; Edgar, Cory

doi:10.1177/0363546515611652

Cited by 74 publications

(57 citation statements)

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“…Our findings validate previous results. 10 Moreover, our study is in agreement with that of Ziegler et al, 19 who demonstrated that even using a pure lateral radiological view as recommended by Schöttle et al, 12 the radiological method is not a precise method to determine the anatomic femoral fixation point of the MPFL. In our study, we also used a strict lateral view.…”

Section: Discussionsupporting

confidence: 91%

“…In this ideal situation, the authors found a mean distance of 4.1 mm from the anatomic MPFL attachment. 19 If the lateral radiograph is not strictly lateral, the error is even greater. Just a small 5° rotation will have a significant effect in determining the anatomic femoral fixation point (7.5-9.2 mm).…”

Section: Discussionmentioning

confidence: 99%

“…Just a small 5° rotation will have a significant effect in determining the anatomic femoral fixation point (7.5-9.2 mm). 19 …”

Section: Discussionmentioning

confidence: 99%

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Radiographic Location Does Not Ensure a Precise Anatomic Location of the Femoral Fixation Site in Medial Patellofemoral Ligament Reconstruction

Sanchis-Alfonso

Ramírez-Fuentes

Montesinos-Berry

et al. 2017

Orthopaedic Journal of Sports Medicine

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Background:A frequently used method to determine the anatomic femoral fixation point in the operating room during medial patellofemoral ligament (MPFL) reconstruction is the radiographic method. However, the ability of this radiological method to establish an anatomic femoral attachment point might not be as accurate as expected.Purpose:(1) To evaluate the accuracy of the radiological method to locate the anatomic femoral fixation point in MPFL reconstruction surgery and (2) to determine the factors influencing the predictability of this method to obtain this objective.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:A total of 100 consecutive 3-dimensional computed tomography (3D CT) knee examinations were performed at 0° of extension in 87 patients treated for chronic lateral patellar instability. For each knee, 2 virtual 7 mm–diameter femoral tunnels were created: 1 using the adductor tubercle as a landmark (anatomic tunnel) and the other according to the radiological method described by Schöttle et al (radiographic tunnel). We measured the percentage of overlap between both tunnels. Moreover, of the 100 included knees, 10 were randomly selected for a variability study.Results:Considering an overlap area greater than 50% as reasonable, the radiographic method achieved this in only 38 of the 100 knees. Intrarater and interrater reliability were excellent. There was a trend for female patients with severe trochlear dysplasia to have less overlap. This model accounted for 64.2% of the initial variability in the data.Conclusion:An exact anatomic femoral tunnel placement could not be achieved with the radiographic method. Radiography provided only an approximation and should not be the sole basis for the femoral attachment location. Moreover, in female patients with severe trochlear dysplasia, the radiographic method was less accurate in determining the anatomic femoral fixation point, although differences were not statistically significant.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

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Radiographic Location Does Not Ensure a Precise Anatomic Location of the Femoral Fixation Site in Medial Patellofemoral Ligament Reconstruction

Sanchis-Alfonso

Ramírez-Fuentes

Montesinos-Berry

et al. 2017

Orthopaedic Journal of Sports Medicine

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“…The use of lateral radiographs may also be considered a limitation of this study, especially given recent criticism of the use of radiologic measures due to their inherent risk of error. 50 Although 3-dimensional imaging may provide a more accurate measure of the exact location of the femoral tunnel, this was not a feasible test on this large clinical cohort, and valid and reliable measurement methods have not been reported. The low number of poor tunnels assessed in the cohort may influence the statistical power of this group’s correlation to the BPII.…”

Section: Discussionmentioning

confidence: 95%

Medial Patellofemoral Ligament Reconstruction Femoral Tunnel Accuracy

Hiemstra

Kerslake

Lafave

2017

Orthopaedic Journal of Sports Medicine

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Background:Medial patellofemoral ligament (MPFL) reconstruction is a procedure aimed to reestablish the checkrein to lateral patellar translation in patients with symptomatic patellofemoral instability. Correct femoral tunnel position is thought to be crucial to successful MPFL reconstruction, but the accuracy of this statement in terms of patient outcomes has not been tested.Purpose:To assess the accuracy of femoral tunnel placement in an MPFL reconstruction cohort and to determine the correlation between tunnel accuracy and a validated disease-specific, patient-reported quality-of-life outcome measure.Study Design:Case series; Level of evidence, 4.Methods:Between June 2008 and February 2014, a total of 206 subjects underwent an MPFL reconstruction. Lateral radiographs were measured to determine the accuracy of the femoral tunnel by measuring the distance from the center of the femoral tunnel to the Schöttle point. Banff Patella Instability Instrument (BPII) scores were collected a mean 24 months postoperatively.Results:A total of 155 (79.5%) subjects had adequate postoperative lateral radiographs and complete BPII scores. The mean duration of follow-up (±SD) was 24.4 ± 8.2 months (range, 12-74 months). Measurement from the center of the femoral tunnel to the Schöttle point resulted in 143 (92.3%) tunnels being categorized as “good” or “ideal.” There were 8 failures in the cohort, none of which occurred in malpositioned tunnels. The mean distance from the center of the MPFL tunnel to the center of the Schöttle point was 5.9 ± 4.2 mm (range, 0.5-25.9 mm). The mean postoperative BPII score was 65.2 ± 22.5 (range, 9.2-100). Pearson r correlation demonstrated no statistically significant relationship between accuracy of femoral tunnel position and BPII score (r = –0.08; 95% CI, –0.24 to 0.08).Conclusion:There was no evidence of a correlation between the accuracy of MPFL reconstruction femoral tunnel in relation to the Schöttle point and disease-specific quality-of-life scores. Graft failure was not related to femoral tunnel placement. The patellofemoral instability population is complex, and patients present with multiple risk factors that, in addition to the accuracy of femoral tunnel position, contribute to quality of life and warrant further investigation.

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“…Ziegler et al [ 26 ] emphasised the importance of a true lateral radiograph using normal cadaveric knees. The position of the MPFL tunnel was 4 mm away from the true MPFL origin as defined by dissection, worsened by even 2.5° rotation of the image.…”

Section: Discussionmentioning

confidence: 99%

The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study

Campos

Soogumbur

McNamara

et al. 2017

Knee Surg Sports Traumatol Arthrosc

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PurposeThe purpose of the study was to investigate the theoretical isometric point based of the curve of the femoral groove and relating it to the origin of the MPFL femoral tunnel on lateral radiograph by comparing a patellar instability cohort with a control cohort.MethodsFrom a Patellar Instability database the radiographs of 40 consecutive patients were analysed to define Schöttle’s point, and the arc of the circle of the trochlear groove. A comparison population of 20 radiographs from comparable patients with tibiofemoral joint disorders was used as a control. The distance from Schöttle’s point to the most anterior part of the groove (extension) was also compared to the distance to the distal end of the roof of the notch (flexion).ResultsThe trochlea was circular in the controls but not the Patellofemoral Instability cohort where trochlear dysplasia is usually present. The difference between the extension and flexion length was a mean of − 2.0 ± 0.5 mm in the controls and + 6.0 ± 0.5 mm in the patellofemoral cohort. In neither cohort did the centre of the circle correspond to Schöttle’s point. The extension distance correlated with the boss height.ConclusionsThe dysplastic trochlea is not circular and the centre of the best matched circle was different to the control trochleae which were circular. The circle centres did not correlate with Schöttle’s point for either cohort, and was more proximal in the Patellofemoral Instability cohort.Clinical relevanceFor the MPFL to have equal tension throughout flexion within the groove, the length should not change. In normal knees the MPFL does not behave isometrically. The change in length, as measured from Schöttle’s point to the trochlea, was greater for patellofemoral instability patients explaining why an isolated MPFL reconstruction in the presence of severe trochlear dysplasia risks poor outcomes. Level of evidence III.

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Radiographic Reference Points Are Inaccurate With and Without a True Lateral Radiograph

Cited by 74 publications

References 50 publications

Radiographic Location Does Not Ensure a Precise Anatomic Location of the Femoral Fixation Site in Medial Patellofemoral Ligament Reconstruction

Radiographic Location Does Not Ensure a Precise Anatomic Location of the Femoral Fixation Site in Medial Patellofemoral Ligament Reconstruction

Medial Patellofemoral Ligament Reconstruction Femoral Tunnel Accuracy

The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study

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