Journal of Orthopaedic Surgery 2014;22(2):248-51
The use of a modified fulcrum for fulcrum bending radiographs: a technical note Kenneth MC Cheung, Josephine WN Lam, Dino Samartzis, William W Lu, Keith DK Luk Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong
INTRODUCTION ABSTRACT We describe a modified fulcrum design to overcome limitations of a traditional fulcrum. The modified fulcrum is a triangular prism–shaped foam with rounded and padded edges. The 3 faces of the fulcrum represent 3 different heights (17.0 cm, 17.5 cm, and 21.0 cm). For fulcrum bending radiographs of the thoracic curve, the patient is placed on an X-ray table in a lateral decubitus position over the fulcrum. The apex of the appropriate height of the fulcrum is positioned under the rib corresponding to the apex of the curve, such that the ipsilateral shoulder is lifted off the X-ray table for maximum passive bending force to the curve. For fulcrum bending radiographs of the lumbar curve, the fulcrum is positioned directly under the apex of the curve such that the ipsilateral iliac crest is lifted off the X-ray table. Key words: radiography; scoliosis; spine
In patients with adolescent idiopathic scoliosis (AIS), the flexibility of spinal curvatures is assessed to identify the characteristics of the curve and facilitate clinical decision-making in terms of levels to be fused, the extent of expected surgical correction, and whether additional surgical intervention is necessary.1,2 Methods to assess spinal flexibility include the use of active lateral bending,3–6 pronepush,7,8 supine traction,9,10 and fulcrum bending radiographs.1,11–27 Fulcrum bending radiography was first used to assess spinal flexibility in AIS patients with hook systems.1 A fulcrum is a padded, radiolucent cylinder placed under the rib corresponding to the apex of the curve while the patient is placed in the lateral decubitus position.1 This method uses passive rather than active forces and reduces personnel exposure of ionising radiation, compared with supine traction radiography.1 Fulcrum bending radiography is more predictive of the degree of curve flexibility and the amount of curve correction, compared with supine bending radiography.1 Fulcrum bending radiography
Address correspondence and reprint requests to: Prof Keith DK Luk, Department of Orthopaedics and Traumatology, The University of Hong Kong, 102 Pokfulam Road, Pokfulam, Hong Kong. Email: [email protected]
Vol. 22 No. 2, August 2014
The use of a modified fulcrum for fulcrum bending radiographs 249
facilitates selection of fusion levels in patients with thoracic AIS.17 Its predictive value in the setting of pedicle screw constructs has been validated.12,14 The fulcrum bending correction index is a preferred tool to describe the degree of scoliosis correction by taking into account the curve flexibility.16 The index has been used to compare scoliosis correction after different instrumentations.18 Although fulcrum bending radiography is increasingly popular, the technique has some limitations. The fulcrum may roll during patient positioning; the hard material is uncomfortable for thin patients or those with large curves; and multiple sizes are needed. Thus, a modified fulcrum is developed and its use is described below.
lateral decubitus position over the fulcrum. The apex of the appropriate height of the fulcrum is positioned under the rib corresponding to the apex of the curve, such that the ipsilateral shoulder is lifted off the X-ray table for maximum passive bending force to the curve (Fig. 2). The hips and knees are flexed slightly to avoid rolling. If necessary, additional sandbags are used. The pelvis and shoulder are perpendicular to the X-ray beam. After radiography, the correct positioning of the fulcrum under the apex of the curve is verified by comparing the standing anteroposterior radiographs and fulcrum bending radiographs (Fig. 3). For fulcrum bending radiographs of the lumbar curve, the fulcrum is positioned directly under the
TECHNICAL NOTE The modified fulcrum is a triangular prism–shaped foam with rounded and padded edges (Fig. 1). The 3 faces of the fulcrum represent 3 different heights (17.0 cm, 17.5 cm, and 21.0 cm). For the thoracic curve with an apex at T7 or below, standing anteroposterior radiographs of the whole spine are first taken to locate the rib corresponding to the apex of the curve. For fulcrum bending radiographs of the thoracic curve, the patient is placed on an X-ray table in a
(a)
(b)
Figure 1 A triangular prism–shaped fulcrum.
Figure 2 (a) For fulcrum bending radiographs of the thoracic curve, the patient is placed on an X-ray table in a lateral decubitus position over the fulcrum. The apex of the appropriate height of the fulcrum is positioned under the rib corresponding to the apex of the curve such that the ipsilateral shoulder is lifted off (arrow) the X-ray table for maximum passive bending force to the curve. The hips and knees should be flexed slightly to avoid rolling. The pelvis and shoulder should be perpendicular to the X-ray beam. (b) For fulcrum bending radiographs of the lumbar curve, the fulcrum is positioned directly under the apex of the curve such that the ipsilateral iliac crest is lifted off (arrow) the X-ray table.
Journal of Orthopaedic Surgery
250 KMC Cheung et al.
(a)
(b)
Figure 3 The correct positioning of the fulcrum under the apex of the (a) thoracic and (b) lumbar curves is verified by comparing the standing anteroposterior radiographs and fulcrum bending radiographs.
apex of the curve, such that the ipsilateral iliac crest is lifted off the X-ray table.
comfortable to use for assessing the flexibility of the spinal curve in AIS patients.
CONCLUSION
DISCLOSURE
The modified fulcrum is convenient, simple, and
No conflicts of interest were declared by the authors.
REFERENCES 1. Cheung KM, Luk KD. Prediction of correction of scoliosis with use of the fulcrum bending radiograph. J Bone Joint Surg Am 1997;79:1144–50. 2. Hamzaoglu A, Talu U, Tezer M, Mirzanli C, Domanic U, Goksan SB. Assessment of curve flexibility in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2005;30:1637–42. 3. Byrd JA 3rd, Scoles PV, Winter RB, Bradford DS, Lonstein JE, Moe JH. Adult idiopathic scoliosis treated by anterior and posterior spinal fusion. J Bone Joint Surg Am 1987;69:843–50. 4. Large DF, Doig WG, Dickens DR, Torode IP, Cole WG. Surgical treatment of double major scoliosis. Improvement of the lumbar curve after fusion of the thoracic curve. J Bone Joint Surg Br 1991;73:121–4. 5. McCall RE, Bronson W. Criteria for selective fusion in idiopathic scoliosis using Cotrel-Dubousset instrumentation. J Pediatr Orthop 1992;12:475–9. 6. Vaughan JJ, Winter RB, Lonstein JE. Comparison of the use of supine bending and traction radiographs in the selection of the fusion area in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 1996;21:2469–73. 7. Kleinman RG, Csongradi JJ, Rinksy LA, Bleck EE. The radiographic assessment of spinal flexibility in scoliosis: a study of the efficacy of the prone push film. Clin Orthop Relat Res 1982;162:47–53. 8. Vedantam R, Lenke LG, Bridwell KH, Linville DL. Comparison of push-prone and lateral-bending radiographs for predicting postoperative coronal alignment in thoracolumbar and lumbar scoliotic curves. Spine (Phila Pa 1976) 2000;25:76–81. 9. Duval-Beaupere G, Lespargot A, Grossiord A. Flexibility of scoliosis. What does it mean? Is this terminology appropriate? Spine (Phila Pa 1976) 1985;10:428–32. 10. Polly DW Jr, Sturm PF. Traction versus supine side bending. Which technique best determines curve flexibility? Spine (Phila Pa 1976) 1998;23:804–8. 11. Cheung KM, Lu DS, Zhang H, Luk KD. In-vivo demonstration of the effectiveness of thoracoscopic anterior release using the fulcrum-bending radiograph: a report of five cases. Eur Spine J 2006;15(Suppl 5):578–82. 12. Cheung KM, Natarajan D, Samartzis D, Wong YW, Cheung WY, Luk KD. Predictability of the fulcrum bending radiograph in scoliosis correction with alternate-level pedicle screw fixation. J Bone Joint Surg Am 2010;92:169–76.
Vol. 22 No. 2, August 2014
The use of a modified fulcrum for fulcrum bending radiographs 251
13. Cheung KM, Wu JP, Cheng QH, Ma BS, Gao JC, Luk KD. Treatment of stiff thoracic scoliosis by thoracoscopic anterior release combined with posterior instrumentation and fusion. J Orthop Surg Res 2007;2:16. 14. Cheung WY, Lenke LG, Luk KD. Prediction of scoliosis correction with thoracic segmental pedicle screw constructs using fulcrum bending radiographs. Spine (Phila Pa 1976) 2010;35:557–61. 15. Li J, Dumonski ML, Samartzis D, Hong J, He S, Zhu X, et al. Coronal deformity correction in adolescent idiopathic scoliosis patients using the fulcrum-bending radiograph: a prospective comparative analysis of the proximal thoracic, main thoracic, and thoracolumbar/lumbar curves. Eur Spine J 2011;20:105–11. 16. Luk KD, Cheung KM, Lu DS, Leong JC. Assessment of scoliosis correction in relation to flexibility using the fulcrum bending correction index. Spine (Phila Pa 1976) 1998;23:2303–7. 17. Luk KD, Don AS, Chong CS, Wong YW, Cheung KM. Selection of fusion levels in adolescent idiopathic scoliosis using fulcrum bending prediction: a prospective study. Spine (Phila Pa 1976) 2008;33:2192–8. 18. Luk KD, Lu DS, Cheung KM, Wong YW. A prospective comparison of the coronal deformity correction in thoracic scoliosis using four different instrumentations and the fulcrum-bending radiograph. Spine (Phila Pa 1976) 2004;29:560–3. 19. Luk KD, Vidyadhara S, Lu DS, Wong YW, Cheung WY, Cheung KM. Coupling between sagittal and frontal plane deformity correction in idiopathic thoracic scoliosis and its relationship with postoperative sagittal alignment. Spine (Phila Pa 1976) 2010;35:1158–64. 20. Sun YQ, Samartzis D, Cheung KM, Wong YW, Luk KD. The ”X-Factor” index: a new parameter for the assessment of adolescent idiopathic scoliosis correction. Eur Spine J 2011;20:144–50. 21. Fei Q, Wang YP, Qiu GX, Zhao Y, Shen JX, Zhang JG, et al. Assessment of curve flexibility in adolescent idiopathic scoliosis before operation [in Chinese]. Zhonghua Yi Xue Za Zhi 2007;87:2484–8. 22. Hay D, Izatt MT, Adam CJ, Labrom RD, Askin GN. The use of fulcrum bending radiographs in anterior thoracic scoliosis correction: a consecutive series of 90 patients. Spine (Phila Pa 1976) 2008;33:999–1005. 23. Ibrahim T, Gabbar OA, El-Abed K, Hutchinson MJ, Nelson IW. The value of radiographs obtained during forced traction under general anaesthesia in predicting flexibility in idiopathic scoliosis with Cobb angles exceeding 60 degree. J Bone Joint Surg Br 2008;90:1473–6. 24. Klepps SJ, Lenke LG, Bridwell KH, Bassett GS, Whorton J. Prospective comparison of flexibility radiographs in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2001;26:E74–9. 25. Little JP, Adam C. Towards determining soft tissue properties for modelling spine surgery: current progress and challenges. Med Biol Eng Comput 2012;50:199–209. 26. Little JP, Adam CJ. The effect of soft tissue properties on spinal flexibility in scoliosis: biomechanical simulation of fulcrum bending. Spine (Phila Pa 1976) 2009;34:E76–82. 27. Lowe TG, Alongi PR, Smith DA, O’Brien MF, Mitchell SL, Pinteric RJ. Anterior single rod instrumentation for thoracolumbar adolescent idiopathic scoliosis with and without the use of structural interbody support. Spine (Phila Pa 1976) 2003;28:2232– 42.
The use of a modified fulcrum for fulcrum bending radiographs: a technical note Kenneth MC Cheung, Josephine WN Lam, Dino Samartzis, William W Lu, Keith DK Luk Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong
INTRODUCTION ABSTRACT We describe a modified fulcrum design to overcome limitations of a traditional fulcrum. The modified fulcrum is a triangular prism–shaped foam with rounded and padded edges. The 3 faces of the fulcrum represent 3 different heights (17.0 cm, 17.5 cm, and 21.0 cm). For fulcrum bending radiographs of the thoracic curve, the patient is placed on an X-ray table in a lateral decubitus position over the fulcrum. The apex of the appropriate height of the fulcrum is positioned under the rib corresponding to the apex of the curve, such that the ipsilateral shoulder is lifted off the X-ray table for maximum passive bending force to the curve. For fulcrum bending radiographs of the lumbar curve, the fulcrum is positioned directly under the apex of the curve such that the ipsilateral iliac crest is lifted off the X-ray table. Key words: radiography; scoliosis; spine
In patients with adolescent idiopathic scoliosis (AIS), the flexibility of spinal curvatures is assessed to identify the characteristics of the curve and facilitate clinical decision-making in terms of levels to be fused, the extent of expected surgical correction, and whether additional surgical intervention is necessary.1,2 Methods to assess spinal flexibility include the use of active lateral bending,3–6 pronepush,7,8 supine traction,9,10 and fulcrum bending radiographs.1,11–27 Fulcrum bending radiography was first used to assess spinal flexibility in AIS patients with hook systems.1 A fulcrum is a padded, radiolucent cylinder placed under the rib corresponding to the apex of the curve while the patient is placed in the lateral decubitus position.1 This method uses passive rather than active forces and reduces personnel exposure of ionising radiation, compared with supine traction radiography.1 Fulcrum bending radiography is more predictive of the degree of curve flexibility and the amount of curve correction, compared with supine bending radiography.1 Fulcrum bending radiography
Address correspondence and reprint requests to: Prof Keith DK Luk, Department of Orthopaedics and Traumatology, The University of Hong Kong, 102 Pokfulam Road, Pokfulam, Hong Kong. Email: [email protected]
Vol. 22 No. 2, August 2014
The use of a modified fulcrum for fulcrum bending radiographs 249
facilitates selection of fusion levels in patients with thoracic AIS.17 Its predictive value in the setting of pedicle screw constructs has been validated.12,14 The fulcrum bending correction index is a preferred tool to describe the degree of scoliosis correction by taking into account the curve flexibility.16 The index has been used to compare scoliosis correction after different instrumentations.18 Although fulcrum bending radiography is increasingly popular, the technique has some limitations. The fulcrum may roll during patient positioning; the hard material is uncomfortable for thin patients or those with large curves; and multiple sizes are needed. Thus, a modified fulcrum is developed and its use is described below.
lateral decubitus position over the fulcrum. The apex of the appropriate height of the fulcrum is positioned under the rib corresponding to the apex of the curve, such that the ipsilateral shoulder is lifted off the X-ray table for maximum passive bending force to the curve (Fig. 2). The hips and knees are flexed slightly to avoid rolling. If necessary, additional sandbags are used. The pelvis and shoulder are perpendicular to the X-ray beam. After radiography, the correct positioning of the fulcrum under the apex of the curve is verified by comparing the standing anteroposterior radiographs and fulcrum bending radiographs (Fig. 3). For fulcrum bending radiographs of the lumbar curve, the fulcrum is positioned directly under the
TECHNICAL NOTE The modified fulcrum is a triangular prism–shaped foam with rounded and padded edges (Fig. 1). The 3 faces of the fulcrum represent 3 different heights (17.0 cm, 17.5 cm, and 21.0 cm). For the thoracic curve with an apex at T7 or below, standing anteroposterior radiographs of the whole spine are first taken to locate the rib corresponding to the apex of the curve. For fulcrum bending radiographs of the thoracic curve, the patient is placed on an X-ray table in a
(a)
(b)
Figure 1 A triangular prism–shaped fulcrum.
Figure 2 (a) For fulcrum bending radiographs of the thoracic curve, the patient is placed on an X-ray table in a lateral decubitus position over the fulcrum. The apex of the appropriate height of the fulcrum is positioned under the rib corresponding to the apex of the curve such that the ipsilateral shoulder is lifted off (arrow) the X-ray table for maximum passive bending force to the curve. The hips and knees should be flexed slightly to avoid rolling. The pelvis and shoulder should be perpendicular to the X-ray beam. (b) For fulcrum bending radiographs of the lumbar curve, the fulcrum is positioned directly under the apex of the curve such that the ipsilateral iliac crest is lifted off (arrow) the X-ray table.
Journal of Orthopaedic Surgery
250 KMC Cheung et al.
(a)
(b)
Figure 3 The correct positioning of the fulcrum under the apex of the (a) thoracic and (b) lumbar curves is verified by comparing the standing anteroposterior radiographs and fulcrum bending radiographs.
apex of the curve, such that the ipsilateral iliac crest is lifted off the X-ray table.
comfortable to use for assessing the flexibility of the spinal curve in AIS patients.
CONCLUSION
DISCLOSURE
The modified fulcrum is convenient, simple, and
No conflicts of interest were declared by the authors.
REFERENCES 1. Cheung KM, Luk KD. Prediction of correction of scoliosis with use of the fulcrum bending radiograph. J Bone Joint Surg Am 1997;79:1144–50. 2. Hamzaoglu A, Talu U, Tezer M, Mirzanli C, Domanic U, Goksan SB. Assessment of curve flexibility in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2005;30:1637–42. 3. Byrd JA 3rd, Scoles PV, Winter RB, Bradford DS, Lonstein JE, Moe JH. Adult idiopathic scoliosis treated by anterior and posterior spinal fusion. J Bone Joint Surg Am 1987;69:843–50. 4. Large DF, Doig WG, Dickens DR, Torode IP, Cole WG. Surgical treatment of double major scoliosis. Improvement of the lumbar curve after fusion of the thoracic curve. J Bone Joint Surg Br 1991;73:121–4. 5. McCall RE, Bronson W. Criteria for selective fusion in idiopathic scoliosis using Cotrel-Dubousset instrumentation. J Pediatr Orthop 1992;12:475–9. 6. Vaughan JJ, Winter RB, Lonstein JE. Comparison of the use of supine bending and traction radiographs in the selection of the fusion area in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 1996;21:2469–73. 7. Kleinman RG, Csongradi JJ, Rinksy LA, Bleck EE. The radiographic assessment of spinal flexibility in scoliosis: a study of the efficacy of the prone push film. Clin Orthop Relat Res 1982;162:47–53. 8. Vedantam R, Lenke LG, Bridwell KH, Linville DL. Comparison of push-prone and lateral-bending radiographs for predicting postoperative coronal alignment in thoracolumbar and lumbar scoliotic curves. Spine (Phila Pa 1976) 2000;25:76–81. 9. Duval-Beaupere G, Lespargot A, Grossiord A. Flexibility of scoliosis. What does it mean? Is this terminology appropriate? Spine (Phila Pa 1976) 1985;10:428–32. 10. Polly DW Jr, Sturm PF. Traction versus supine side bending. Which technique best determines curve flexibility? Spine (Phila Pa 1976) 1998;23:804–8. 11. Cheung KM, Lu DS, Zhang H, Luk KD. In-vivo demonstration of the effectiveness of thoracoscopic anterior release using the fulcrum-bending radiograph: a report of five cases. Eur Spine J 2006;15(Suppl 5):578–82. 12. Cheung KM, Natarajan D, Samartzis D, Wong YW, Cheung WY, Luk KD. Predictability of the fulcrum bending radiograph in scoliosis correction with alternate-level pedicle screw fixation. J Bone Joint Surg Am 2010;92:169–76.
Vol. 22 No. 2, August 2014
The use of a modified fulcrum for fulcrum bending radiographs 251
13. Cheung KM, Wu JP, Cheng QH, Ma BS, Gao JC, Luk KD. Treatment of stiff thoracic scoliosis by thoracoscopic anterior release combined with posterior instrumentation and fusion. J Orthop Surg Res 2007;2:16. 14. Cheung WY, Lenke LG, Luk KD. Prediction of scoliosis correction with thoracic segmental pedicle screw constructs using fulcrum bending radiographs. Spine (Phila Pa 1976) 2010;35:557–61. 15. Li J, Dumonski ML, Samartzis D, Hong J, He S, Zhu X, et al. Coronal deformity correction in adolescent idiopathic scoliosis patients using the fulcrum-bending radiograph: a prospective comparative analysis of the proximal thoracic, main thoracic, and thoracolumbar/lumbar curves. Eur Spine J 2011;20:105–11. 16. Luk KD, Cheung KM, Lu DS, Leong JC. Assessment of scoliosis correction in relation to flexibility using the fulcrum bending correction index. Spine (Phila Pa 1976) 1998;23:2303–7. 17. Luk KD, Don AS, Chong CS, Wong YW, Cheung KM. Selection of fusion levels in adolescent idiopathic scoliosis using fulcrum bending prediction: a prospective study. Spine (Phila Pa 1976) 2008;33:2192–8. 18. Luk KD, Lu DS, Cheung KM, Wong YW. A prospective comparison of the coronal deformity correction in thoracic scoliosis using four different instrumentations and the fulcrum-bending radiograph. Spine (Phila Pa 1976) 2004;29:560–3. 19. Luk KD, Vidyadhara S, Lu DS, Wong YW, Cheung WY, Cheung KM. Coupling between sagittal and frontal plane deformity correction in idiopathic thoracic scoliosis and its relationship with postoperative sagittal alignment. Spine (Phila Pa 1976) 2010;35:1158–64. 20. Sun YQ, Samartzis D, Cheung KM, Wong YW, Luk KD. The ”X-Factor” index: a new parameter for the assessment of adolescent idiopathic scoliosis correction. Eur Spine J 2011;20:144–50. 21. Fei Q, Wang YP, Qiu GX, Zhao Y, Shen JX, Zhang JG, et al. Assessment of curve flexibility in adolescent idiopathic scoliosis before operation [in Chinese]. Zhonghua Yi Xue Za Zhi 2007;87:2484–8. 22. Hay D, Izatt MT, Adam CJ, Labrom RD, Askin GN. The use of fulcrum bending radiographs in anterior thoracic scoliosis correction: a consecutive series of 90 patients. Spine (Phila Pa 1976) 2008;33:999–1005. 23. Ibrahim T, Gabbar OA, El-Abed K, Hutchinson MJ, Nelson IW. The value of radiographs obtained during forced traction under general anaesthesia in predicting flexibility in idiopathic scoliosis with Cobb angles exceeding 60 degree. J Bone Joint Surg Br 2008;90:1473–6. 24. Klepps SJ, Lenke LG, Bridwell KH, Bassett GS, Whorton J. Prospective comparison of flexibility radiographs in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2001;26:E74–9. 25. Little JP, Adam C. Towards determining soft tissue properties for modelling spine surgery: current progress and challenges. Med Biol Eng Comput 2012;50:199–209. 26. Little JP, Adam CJ. The effect of soft tissue properties on spinal flexibility in scoliosis: biomechanical simulation of fulcrum bending. Spine (Phila Pa 1976) 2009;34:E76–82. 27. Lowe TG, Alongi PR, Smith DA, O’Brien MF, Mitchell SL, Pinteric RJ. Anterior single rod instrumentation for thoracolumbar adolescent idiopathic scoliosis with and without the use of structural interbody support. Spine (Phila Pa 1976) 2003;28:2232– 42.
