Do we need Transverse Connectors to maintain Derotation in Scoliosis Constructs?
Arvind G Kulkarni, Shashidhar B Kantharajanna, Abhilash Dhruv, Anupreet Bassi
Citation Information :
Kulkarni AG, Kantharajanna SB, Dhruv A, Bassi A. Do we need Transverse Connectors to maintain Derotation in Scoliosis Constructs?. J Spinal Surg 2017; 4 (1):4-8.
There are numerous biomechanical studies, but no clinical study to support or refute the use of transverse connectors (TCs) in scoliosis constructs. The aim of the study is to critically assess the role of TCs in scoliosis constructs.
Material and methods
All patients of scoliosis that underwent pedicle screw constructs without the use of TCs between July 2007 and July 2011 were evaluated. The immediate postoperative erect radiographs were compared with the erect radiographs at the last follow-up (at least 12 months) by two independent observers (spine fellows). The radiographs were assessed critically for any rotation at the apical vertebra using the Nash–Moe technique. The intraobserver and interobserver reliability were analyzed. The radiographs were additionally evaluated for any loss of correction and implant failure.
Results
There were 28 cases in the study. The total number of levels fused was 277. The average follow-up was 33 months. The average preoperative Cobb angle of the major curve was 72.5° (40–110°) and postoperative angle was 24.75° (5–50°). The mean percentage correction in the preoperative and postoperative Cobb angle of the major curve was 68.88% (46.80–92.3%). The intraobserver reliability was 100%; there was no change in the rotation of the levels evaluated by either observer. The interobserver reliability was 100%. There were no cases of implant failure. There were two cases of distal junctional kyphosis requiring extension of construct distally, not attributable to implant characteristics.
Conclusion
The TCs are not essential to maintain derotation and do not add to stability of long scoliosis constructs. The authors make a strong statement that TCs may not be necessary to maintain derotation in scoliosis constructs.
Clinical significance
The additional complications of implant prominence, metal corrosion, skin breakdown, pseudoarthrosis, and costs can be prevented by excluding TCs from the scoliosis constructs.
How to cite this article
Kulkarni AG, Kantharajanna SB, Dhruv A, Bassi A. Do we need Transverse Connectors to maintain Derotation in Scoliosis Constructs? J Spinal Surg 2017;4(1):4-8.
Possibilities and limitations of Harrington's method in the surgical treatment of scoliosis. Arch Orthop Unfallchir 1971;70(2):136-151.
New segmental posterior instrumentation of the spine. Orthop Trans 1985;9(1):118.
A modular spinal rod linkage system to provide rotational stability. Spine (Phila Pa 1976) 1988 Mar;13(3):272-277.
Mechanical testing of spinal instrumentation. Clin Orthop Relat Res 1988 Feb;227:113-125.
Mechanical effects of cross-linking rods in Cotrel—Dubousset instrumentation. Orthop Trans 1987;11:96-97.
Biomechanical analysis of pedicle screw instrumentation systems in a corpectomy model. Spine (Phila Pa 1976) 1989 Dec;14(12):1398-1405.
Lumbar pedicle screws versus hooks. Results in double major curves in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 1997 Jun;22(12):1369-1379.
Torsional rigidity of scoliosis constructs. Spine (Phila Pa 1976) 2000 Aug;25(15):1893-1898.
Mechanical evaluation of cross-link designs in rigid pedicle screw systems. Spine (Phila Pa 1976) 1997 Feb;22(4):370-375.
Mechanical stability of thoracolumbar pedicle screw fixation. The effect of crosslinks. Spine (Phila Pa 1976) 1997 Jul;22(14):1568-1572.
Biomechanics of transfixation in pedicle screw instrumentation. Spine (Phila Pa 1976) 1996 Oct;21(19):2224-2229.
Biomechanical evaluation of diagonal fixation in pedicle screw instrumentation. Spine (Phila Pa 1976) 2001 Nov;26(22):2498-2503.
Segmental pedicle screw fixation or cross-links in multilevel lumbar constructs. A biomechanical analysis. Spine J 2001 Sep-Oct;1(5):373-379.
Biomechanics of thoracolumbar spinal fixation. A review. Spine (Phila Pa 1976) 1991 Mar;16(Suppl 3):S84-S98.
; Caruso SA.; Gorup JM.; Haher TR. Effects of transverse connectors on rotational stiffness in a vertebrectomy model. Scoliosis Research Society 31st annual meeting, Ottawa, Canada, September 25-28, 1996.
Internal forces and moments in transpedicular spine instrumentation. The effect of pedicle screw angle and transfixation: The 4R-4bar linkage concept. Spine (Phila Pa 1976) 1990 Sep;15(9):893-901.
; Tahmoush KM.; Thopmas KA. Biomechanical testing of pedicle screws versus lamina hooks as distal anchors for scoliosis instrumentation. Scoliosis Research Society 32nd annual meeting, St. Louis, MO, September 25-27, 1997.
A study of vertebral rotation. J Bone Joint Surg 1969 Mar;51(2):223-229.
Cotrel–Dubousset instrumentation in the treatment of adolescent idiopathic scoliosis. In: Bridwell KH.; DeWald RL., editors. The textbook of spinal surgery. 2nd ed. Philadelphia, PA: Lippincott–Raven Press; 1997. p. 489-534.
; Asher MA. The frequency of re-entry following primary posterior instrumentation and fusion for idiopathic scoliosis: Harrington, CD, and Isola. Paper presented at: Scoliosis Research Society 31st annual meeting, Ottawa, Canada, September 25–28, 1996.
Lenke classification system of adolescent idiopathic scoliosis: treatment recommendations. Instr Course Lect 2005;54:537-542.
Delayed infections after posterior TSRH spinal instrumentation for idiopathic scoliosis: revisited. Spine (Phila Pa 1976) 2001 Sep;26(18):1990-1996.
Mechanical stability of thoracolumbar pedicle screw fixation: the effects of crosslinks. Spine (Phila Pa 1976) 1997 Jul;22(14):1568-1572.
Should we cross the cross-links? Spine (Phila Pa 1976) 2013 Aug;38(18):E1128-E1134.
Effectiveness of cross-linking posterior segmental instrumentation in adolescent idiopathic scoliosis: a 2-year follow-up comparative study. Spine J 2013 Nov;13(11):1485-1492.
Cross-links do not improve clinical or radiographic outcomes of posterior spinal fusion with pedicle screws in adolescent idiopathic scoliosis: a multicenter cohort study. Spine Deform 2015 Jul;3(4):338-344.
