Foot and ankle radiographic parameters: validity and reproducibility of biplane imaging system versus conventional radiography

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Jessica E. Goetz, PhD; Marut Arunakul, MD; Yubo, Gao, PhD; John E.

1 Foot and ankle radiographic parameters: validity and reproducibility of biplane imaging system versus conventional radiography Chamnanni Rungpai, MD; Jessica E. Goetz, PhD; Marut Arunakul, MD; Yubo, Gao, PhD; John E. Femino, MD; Annunziato Amendola, MD; Phinit Phisitkul, MD University of Iowa Hospital and Clinics

2 Foot and ankle radiographic parameters: validity and reproducibility of biplane imaging system versus conventional radiography Chamnanni Rungpai, MD My disclosure is in the Final AOFAS Mobile App. I have no potential conflicts with this presentation.

Introduction Accurate understanding of foot and ankle alignment is important in the clinical diagnosis, surgical planning, and post-operative follow up.

3 Introduction Accurate understanding of foot and ankle alignment is important in the clinical diagnosis, surgical planning, and post-operative follow up. However, there is currently no radiographic technique that allows complete threedimensional evaluation of the entire lower limbs. Conventional (2D) radiography is commonly used with some limitations such as 1.Magnification error 2.Difficulty in obtain lone leg film 3.Lack of three dimensional information CT scan is alternative option and provides high resolution 3D data but it is not routine practical use due to 1. High cost 2. High radiation exposure 3.Non-weight bearing technique except PedCAT but it is confined only 20 cm from the floor.

Biplane Imaging system Recently, can simultaneously capture two orthogonal AP and lateral view results in better understanding of lower limb in 3D.

Propose The purpose of this study was to evaluate the validity and reproducibility of a biplane imaging system for 2D angular and distance measurements of

4 Biplane Imaging system Recently, can simultaneously capture two orthogonal AP and lateral view results in better understanding of lower limb in 3D. In addition, it is Weight bearing technique No magnification error Low doses of radiation exposure. Propose The purpose of this study was to evaluate the validity and reproducibility of a biplane imaging system for 2D angular and distance measurements of commonly used foot and ankle radiographic parameters compared to conventional radiography. In addition, lower limb alignment, limb length, and limb length discrepancy was compared between the and non feet position.

5 Materials and methods 50 consecutive patients (69 feet) indicated for foot and ankle realignment surgeries were included. Radiographic studies included weight bearing AP and lateral ankle using conventional X-rays Long leg AP non- feet using 2D imaging system. Long leg AP and lateral feet position 2D imaging system. All radiography were performed at the same day. All measurements were measured by two blinded observers. One observer repeating all the measurements at 6 weeks apart.

6 Common foot and ankle parameters, lower limb alignment, and limb length measurement 1. Talocrural angle 2. Tibiofibular clear space 3. Medial clear space 4. Talar tilt angle 5. Lateral distal tibial angle (LDTA) 6.Calcaneal pitch 7. Lateral talo-calcaneal angle 8. Lateral talo-1 st metatarsal angle 9. Medial cuneiform-5 th metatarsal height 10. Anterior distal tibial angle (ADTA) 11. Hip Knee Shaft angle (HKS) 12. Hip Knee Ankle angle (HKA) 13. Femoral Neck Shaft Angle (FNSA) 14. Femur length (front and rear leg) 15. Tibia length (front and rear leg) 16. Entire lower limb length (front and rear leg) 17. Mechanical axis discrepancy technique 18. Total limb length discrepancy technique

structures starting from the 1st metatarsal head of front foot (A) and ending with

7 Optimal foot positioning in long leg lateral view Long leg lateral view weight bearing Long leg AP view weight bearing Staggered feet position: Illustrating osseous structures starting from the 1st metatarsal head of front foot (A) and ending with lowest part of calcaneus of rear foot (B). These pictures showed all parameters in the AP view

8 Comparing between convention X-ray and imaging and non feet position Intraclass Correlation Coefficient (ICCs) AP View Result: One-way ANOVA conventional radiograph compared with non Intra-observer ICC non- Inter-observer ICC non Talocrural angle Talar tilt Tibio-fibular clear space Medial clear space Lateral distal tibial angle

9 Hip Knee Ankle angle (HKA)* Femoral Neck Shaft Angle (FNSA)* (*) HKS, HKA, FNSA were compared between and non- feet position in AP view but the rest of the lateral parameters compared between conventional radiography with the feet position in lateral view. Comparing between conventional x-ray and feet position Intraclass Correlation Coefficient (ICCs) Lateral view Paired t-test p-value Intra-observer ICCs Conventional / non- Inter-observer ICCs Conventional / non- Calcaneal pitch angle Lateral talo-calcaneal angle Lateral talo-1st metatarsal angle Medial cuneiform- 5th metatarsal height Anterior distal tibial angle Hip Knee Shaft angle (HKS)*

10 Comparing between and non- feet position Limb length Limb length discrepancy pair t-test p-value Intraclass Correlation Coefficient (ICCs) Intra-observer ICC non- Inter-observer ICC non- Femur length (front leg) Tibial length (front leg) Entire lower limb length (front leg) Femur length (rear leg) Tibial length (rear leg) Entire lower limb length (rear leg) Limb length discrepancy using mechanical axis technique Limb length discrepancy using entire lower limb technique

11 Limitation Conclusion No patients younger than 15 years old the findings cannot be extrapolated to skeletally immature patients. Difficulties in obtaining acceptable images in some patients. Six percent (4/69) of the subjects were excluded improper positioning within the or poor image quality. The biplane imaging system or TM imaging was a valid and reliable measurement of commonly used foot and ankle radiographic parameters when compared to conventional radiographic methods. Staggered foot positioning allowed simultaneous imaging of both feet in lateral view without affecting limb alignment Except femur length, tibial length, entire lower limb length of the rear leg, and limb length discrepancy measurement.

12 Reference: Chaibi, Y; Cresson, T; Aubert, B, et al.: Fast 3D reconstruction of the lower limb using a parametric model and statistical inferences and clinical measurements calculation from biplanar X-rays. Computer methods in biomechanics and biomedical engineering. 2012;15(5): doi: / Deschenes, S; Charron, G; Beaudoin, G, et al.: Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Spine Apr 20;35(9): doi: /brs.0b013e3181bdcaa4. Guenoun, B; Zadegan, F; Aim, F; Hannouche, D; Nizard, R: Reliability of a new method for lowerextremity measurements based on stereoradiographic three-dimensional reconstruction. Orthopaedics & traumatology, surgery & research Sep;98(5): doi: /j.otsr Sabharwal, S; Zhao, C; McKeon, JJ, et al.: Computed radiographic measurement of limb-length discrepancy. Full-length standing anteroposterior radiograph compared with scanogram. The Journal of bone and joint surgery American volume Oct;88(10): doi.org/ /jbjs.e Escott, BG; Ravi, B; Weathermon, AC, et al.: low-dose radiography: a reliable and accurate upright assessment of lower-limb lengths. The Journal of bone and joint surgery American volume Dec 4;95(23):e doi: /JBJS.L Alonso, CG; Curiel, MD; Carranza, FH; Cano, RP; Perez, AD: Femoral bone mineral density, neck-shaft angle and mean femoral neck width as predictors of hip fracture in men and women. Multicenter Project for Research in Osteoporosis. Osteoporosis international. 2000;11(8): Arunakul, M; Amendola, A; Gao, Y, et al.: Tripod index: a new radiographic parameter assessing foot alignment. Foot & ankle international / American Orthopaedic Foot and Ankle Society [and] Swiss Foot and Ankle Society Oct;34(10): doi: / Takakura, Y; Tanaka, Y; Kumai, T; Tamai, S: Low tibial osteotomy for osteoarthritis of the ankle. Results of a new operation in 18 patients. The Journal of bone and joint surgery British volume Jan;77(1):50-4. Odenbring, S; Berggren, AM; Peil, L: Roentgenographic assessment of the hip-knee-ankle axis in medial gonarthrosis. A study of reproducibility. Clinical orthopaedics and related research Apr;(289):195-6.

Marut Arunakul, M.D. Phinit Phisitkul, M.D. Jessica Goetz, PhD. John Femino, M.D. Annunziato Amendola, M.D. University of Iowa Hospitals and Clinics

Marut Arunakul, M.D. Phinit Phisitkul, M.D. Jessica Goetz, PhD. John Femino, M.D. Annunziato Amendola, M.D. University of Iowa Hospitals and Clinics Tripod Index Part 1: New radiographic parameter assessing