Validation of a Novel Digitally Reconstructed Radiograph Based

Radiostereometric Analysis Method for Evaluation of Femoroacetabular

Impingement Pathomechanics

Lars Hansen BA, Sepp de Raedt MSc PhD, Peter Bo Jørgensen MSc, Bjarne Mygind-Klavsen MD, Maiken Stilling MD PhDDepartment of Orthopedic Research, Aarhus University Hospital, Denmark

Lars Hansen

August 24th 2016 lars.hansen@post.au.dk 2

• I have no financial relations to disclose

Background

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• Femoroacetabular impingement (FAI) is a common cause of hip

pain1

• FAI is associated with early development of osteoarthritis2

• Recommended treatment is by arthroscopic cheilectomy and –

rim trimming (ACH)

• The main cause for surgical revision, after ACH, is failure to

address the CAM- and Pincer deformities3

• In vivo FAI hip joint kinematics and the effects of the ACH are

not well understood4, 5, 6, 7

Dynamic RSA – Current analysis methods

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• With dRSA it is possible to track three dimensional movements of objects using roentgen8

• Current marker based RSA • Invasive and not applicable for diagnostic

purposes• Manual analysis

• Traditional model based RSA • Fitting of bone models by edge detection on

stereoradiographs• Manual analysis and very time consuming

Aim

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• To establish the accuracy and precision of a novel

noninvasive and fully automated digitally

reconstructed radiograph based method (DRR) for

analysis of dynamic radiostereometric (dRSA)

recordings of the hip joint

• To evaluate DRR for investigating clinical in vivo hip

joint kinematics

Digitally reconstructed radiograph

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RSA image DRR DRR fitted to RSA image

• Digital reconstructed radiographs (DRR) were simulated from preoperative CT data

• By matching the DRR and RSA image the position of each bone is determined

Methods – Test protocol

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• Eight fresh frozen non-FAI affected cadaveric hips were acquired

• Procedure:• Preoperative CT-scans were performed and

bone models of the femur and pelvis segmented• 8-10 tantalum markers were inserted in the

proximal femur and the pelvis• dRSA during flexion, adduction and internal

rotation (FADIR)• Arthroscopic cheilectomy

and -rim trimming

• Postoperative CT and –dRSAfor comparison and evaluation

Methods – Analysis

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• Stereoradiographs were acquired and analyzed by:• Marker based RSA (MM) as gold standard9

• Model based RSA (MBM)9

• Digitally reconstructed radiograph RSA (DRR)

• Migratory results of MBM and DRR with respect to MM were measured

• Precision was assessed by• Systematic error (mean difference)• Random variation (Pitman’s test for equal variance)

Results

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• Box plots of migration translation error of DRR and MBM with respect to MM along the three axes Tx, Ty and Tz

• Variance is statistically significantly lower for DRR in all six degrees of freedom (p<0.05)

-2

-1

0

1

2

PostOp Preop PostOp PreopDRR MBM DRR MBM DRR MBM DRR MBM

Femur Pelvis

Tx Ty TzGraphs by group(bone)

Results

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• 288 dRSA images were analyzed• Systematic bias for MBM and DRR with respect to

MM:• Translations: <0.018mm • Rotations: <0.009°• No difference between MBM and DRR (p>0.46)

• Random variation• Lower for DRR in all six degrees of freedom (p<0.00)

• Precision of DRR• Translations:

• Femur: 40% higher precision (Δ0.07mm)• Pelvis: 6 times higher precision (Δ0.40mm)

• Rotations:• Femur: 60% higher precision (Δ0.25°)• Pelvis: Two times higher precision (Δ0.34°)

Conclusions

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• DRR

• Precise method for analysis of dRSA images

• Can be used for clinical studies on kinematic hip

pathology and potentially for diagnostic purposes

• It is automated, noninvasive and not user-dependent

ACKNOWLEDGEMENTS

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Financial support

Co workers

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References1. Larson, C. M., Kelly, B. T., Bhandari, M., Ph, D., Ayeni, O. R., Sc, M., & Bedi, A. (2016). Impingement. Arthroscopy: The Journal of Arthroscopic and Related Surgery,

32(1), 177–189. http://doi.org/10.1016/j.arthro.2015.10.010

2. Kowalczuk, M., Yeung, M., Simunovic, N., & Ayeni, O. R. (2015). Does Femoroacetabular Impingement Contribute to the Development of Hip Osteoarthritis ? A

Systematic Review, 23(4), 174–179.

3. Heyworth, B. E., Shindle, M. K., Voos, J. E., Rudzki, J. R., & Kelly, B. T. (2007). Radiologic and Intraoperative Findings in Revision Hip Arthroscopy. Arthroscopy -

Journal of Arthroscopic and Related Surgery, 23(12), 1295–1302. http://doi.org/10.1016/j.arthro.2007.09.015

4. Bedi, A., Dolan, M., Hetsroni, I., Magennis, E., Lipman, J., Buly, R., & Kelly, B. T. (2011). Surgical Treatment of Femoroacetabular Impingement Improves Hip

Kinematics. The American Journal of Sports Medicine, 39(Supplement 1), 43S–49S. http://doi.org/10.1177/0363546511414635

5. Brisson, N., Lamontagne, M., Kennedy, M. J., & Beaulé, P. E. (2013). The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait

biomechanics. Gait and Posture, 37, 258–263. http://doi.org/10.1016/j.gaitpost.2012.07.016 Kubiak-Langer, Tannast, Murphy, Siebenrock, & Langlotz, 2007;

6. Review, A. E., Sampson, J. D., & Safran, M. R. (2015). Biomechanical Implications of Corrective Surgery for FAI :, 23(4), 169–173.

7. Kapron, A. L., Aoki, S. K., Peters, C. L., & Anderson, A. E. (2015). In-vivo hip arthrokinematics during supine clinical exams: Application to the study of

femoroacetabular impingement. Journal of Biomechanics, 48(11), 1–8. http://doi.org/10.1016/j.jbiomech.2015.04.022

8. Kärrholm, J. (1989). Roentgen stereophotogrammetry. Review of orthopedic applications. Acta Orthopaedica Scandinavica, 60(4), 491–503.

http://doi.org/10.3109/17453678909149328

9. Analyzed using the software Model-Based RSA, RSAcore, Leiden MBRSA, v.4.02