The pedicle screw (PS) system is widely used for spinal reconstruction. Recently, screw insertion using the cortical bone trajectory (CBT) technique has been reported to provide increased holding strength of the vertebra, even in an osteoporotic spine. CBT is also beneficial due to its low invasiveness. We have been performing hybrid reconstruction with CBT at the cranial level and PS at the caudal level based on the concept of minimal invasiveness. We applied this hybrid technique to 6 cases of degenerative spondylolisthesis. Surgery was completed with a small skin incision of around 5-6 cm, which is shorter than that of the conventional PS procedure. The mean percent slippage before surgery was 19.8%, and this was reduced to 3.9% after surgery and almost maintained 3 months after surgery. Furthermore, no major surgical complications were observed. Here, we introduce the minimally invasive hybrid technique of CBT-PS. Surgeons should be aware of the procedure as an option for minimally invasive lumbar spine reconstructive surgery

Goda, Yuichiro

Goto, Tomohiro

Hama, Shingo

Hamada, Daisuke

Higashino, Kosaku

Higuchi, Tadahiro

Kimura, Tetsuya

Kosaka, Hirofumi

Matsuura, Tetsuya

Mineta, Kazuaki

Mishiro, Takuya

Nishisho, Toshihiko

Nitta, Akihiro

Sairyo, Koichi

Sakai, Toshinori

Sato, Ryosuke

Suzue, Naoto

Takata, Yoichiro

Tezuka, Fumitake

Tonogai, Ichiro

Tsutsui, Takahiko

Tokushima University Institutional Repository

INTRODUCTIONSantoni et al. (1) proposed in 2009 a new lumbarspine reconstruction technique called the corticalbone trajectory (CBT) technique. This techniquediffers from the conventional pedicle screw (PS)technique in which a screw is inserted through theanatomical axis of the pedicle into the vertebralbody. In the CBT technique, a screw follows a sag-ittal caudocephalad path and a laterally directed pathin the transverse plane to maximally engage thecortical bone from the pedicle to the vertebral body.Santoni et al. (1) measured the pullout strengths ofthe conventional PS and new CBT technique andfound a 30% increase in uniaxial yield pullout loadwhen employing CBT. Thus, CBT screwing is es-pecially beneficial for osteoporotic spine in elderlypatients.The CBT technique also has other advantagesdue to the screw insertion point. The screw inser-tion through a medial starting point may minimizedamage to the paravertebral muscles, facet joint,ORIGINALHybrid technique of cortical bone trajectory and pediclescrewing for minimally invasive spine reconstructionsurgery : A technical noteYoichiro Takata, Tetsuya Matsuura, Kosaku Higashino, Toshinori Sakai,Takuya Mishiro, Naoto Suzue, Hirofumi Kosaka, Daisuke Hamada, Tomohiro Goto,Toshihiko Nishisho, Yuichiro Goda, Ryosuke Sato, Takahiko Tsutsui, Ichiro Tonogai,Fumitake Tezuka, Kazuaki Mineta, Tetsuya Kimura, Akihiro Nitta, Tadahiro Higuchi,Shingo Hama, and Koichi SairyoDepartment of Orthopedics, the University of Tokushima, Tokushima, JapanAbstract : The pedicle screw (PS) system is widely used for spinal reconstruction. Recently,screw insertion using the cortical bone trajectory (CBT) technique has been reported toprovide increased holding strength of the vertebra, even in an osteoporotic spine. CBT isalso beneficial due to its low invasiveness. We have been performing hybrid reconstructionwith CBT at the cranial level and PS at the caudal level based on the concept of minimalinvasiveness. We applied this hybrid technique to 6 cases of degenerative spondylolisthesis.Surgery was completed with a small skin incision of around 5-6 cm, which is shorter thanthat of the conventional PS procedure. The mean percent slippage before surgery was19.8%, and this was reduced to 3.9% after surgery and almost maintained 3 months aftersurgery. Furthermore, no major surgical complications were observed. Here, we intro-duce the minimally invasive hybrid technique of CBT-PS. Surgeons should be aware ofthe procedure as an option for minimally invasive lumbar spine reconstructive surgery.J. Med. Invest. 61 : 388-392, August, 2014Keywords : lumbar degenerative spondylolisthesis, pedicle screw, cortical bone trajectory, fusion surgeryReceived for publication May 7, 2014 ; accepted June 4, 2014.Address correspondence and reprint requests to YoichiroTakata, MD, PhD, Department of Orthopedics, the Universityof Tokushima, 3-18-15 Kuramoto, Tokushima 770-8503, Japanand Fax : +81-88-633-0178.The Journal of Medical Investigation Vol. 61 2014388㻭㼚㼠㼑㼞㼛㻙㼜㼛㼟㼠㼑㼞㼕㼛㼞㻌㼢㼕㼑㼣 㻸㼍㼠㼑㼞㼍㼘㻌㼢㼕㼑㼣㻾㼕㼓㼔㼠and capsule. Especially on the cranial side of fusion,a conventional PS needs to be inserted laterally fromthe facet joint so that the screw insertion maneuverwill not damage the facet joint and capsule. Thus,to insert a conventional PS at the cranial level offusion, the paravertebral muscles need to be dis-sected laterally to the transverse process includingthe entire lamina. However, the CBT technique atthe cranial level requires soft tissue dissection atonly the inferior part of the lamina. Similarly, at thecaudal level of fusion, CBT needs soft tissue dis-section at the inferior lamina. However, PS at thecaudal level can be inserted without any further dis-section after decompression and facetectomy.Because of the low invasiveness of CBT at thecranial level, we have started to perform a hybridtechnique with CBT at the cranial level and PS atthe caudal level (Figure 1). To date, only a fewstudies have reported on the CBT procedure, andto the best of our knowledge, very few studies havereported on the hybrid CBT-PS technique. In thispaper, we introduce our hybrid technique as a tech-nical note and review the clinical and radiologicaloutcomes of the initial 6 cases of degenerative spon-dylolisthesis.SURGICAL TECHNIQUEWe explain the surgical technique in a represen-tative case of L4 spondylolisthesis. A skin incisionof about 5-6 cm is made around the interlaminararea at L4-5 (Figure 2). Decompression includingL4 laminotomy, L4-5 flavectomy, L5 laminotomy,and single-sided facetectomy is performed. A cageis inserted by the transforaminal interbody fusiontechnique. At L4, 2 screws are inserted by the CBTtechnique on each side, and at L5, 2 PS are insertedaccording to the conventional technique proposedby Roy-Camille et al. (2). Unlike Weinstein’s tech-nique for PS insertion (2), Roy-Camille’s techniquedoes not require paravertebral dissection at thetransverse process. Figure 3 shows the insertionpoint with both PS insertion techniques. The dot-ted lines indicate the pathway for Roy-Camille’stechnique and the straight lines indicate that forWeinstein’s technique.The insertion point of the CBT screw is deter-mined on an anteroposterior radiological view usinga C-arm image intensifier. For the right and leftFigure 1 : Representative radiographs after the hybrid corticalbone trajectory-pedicle screw (CBT-PS) technique. Two screwsinserted by CBT at L4 and 2 conventional PS inserted at L5 areshown. Note the difference in the insertion direction in each pro-cedure.Figure 2 : Incisional skin scar in a patient who underwent CBT-PS.Figure 3 : Insertion point and pathway in each kind of pediclescrewing technique. Dotted lines indicate the pathway for Roy-Camille’s technique and straight lines indicate that for Weinstein’stechnique.The Journal of Medical Investigation Vol. 61 August 2014 389㻾㼠 㼕㼚㼟㼑㼞㼠㼕㼛㼚㻌㼜㼛㼕㼚㼠 㻾㼠 㼕㼚㼟㼑㼞㼠㼕㼛㼚㻌㼜㼛㼕㼚㼠㻔㻭㻕㻌㻰㼞㼕㼘㼘㼕㼚㼓㻌㼛㼒㻌㼠㼔㼑㻌㼐㼛㼞㼟㼍㼘㻌㼟㼡㼞㼒㼍㼏㼑㼛㼒㻌㼠㼔㼑㻌㼘㼍㼙㼕㼚㼍㻔㻮㻕㻌㻼㼞㼛㼢㼕㼚㼓㻌㼕㼚㼟㼕㼐㼑㻌㼠㼔㼑㻌㼜㼑㼐㼕㼏㼘㼑㻌㼣㼍㼘㼘㻔㼏㻕㻌㻼㼞㼛㼢㼕㼚㼓㻌㼕㼚㼟㼕㼐㼑㻌㼠㼔㼑㻌㼢㼑㼞㼠㼑㼎㼞㼍㼘㼎㼛㼐㼥㻔㻰㻕㻌㻿㼏㼔㼑㼙㼍㼠㼕㼏㻌㼕㼘㼘㼡㼟㼠㼞㼍㼠㼕㼛㼚㻌㼛㼒㻌㼕㼚㼟㼑㼞㼠㼕㼛㼚㻌㼛㼒㻌㻯㻮㼀㻌㼟㼏㼞㼑㼣CBT screw insertion, the points are at 7 o’clock and5 o’clock of the pedicle, respectively (Figure 4). Thisis similar to the technique proposed by Matsukawaet al. (3). The lateral view on the image intensifieris used to understand the sagittal trajectory of CBTscrewing (Figure 5). First, the cortex at the inser-tion point is drilled. Then, a pedicle probe is insertedwhile observing the lateral view on the image in-tensifier. For the laterally directed path in the trans-verse plane, screw insertion is performed at 10 de-grees to the insertion angle in the medial to lateraldirection.To reduce slippage in this series, we used theMESA system (K2M Inc., Leesburg, VA). Thepostsurgical radiographs in Figure 1 show that theCBT screws at L4 follow a caudocephalad path inthe sagittal plane and a laterally directed path in thetransverse plane. On the other hand, the screws atL5 are inserted along the anatomic axis of the pedi-cle into the vertebral body.METHODSix cases of degenerative spondylolisthesis weretreated with this hybrid CBT-PS technique. Theaffected vertebra was L3 in 1 case and L4 in theremaining 5 cases. All patients were women, aged55, 65, 72, 75, 76, and 77 years. Clinical outcomewas evaluated by Japanese Orthopaedic Association(JOA) score (4). Radiological outcome was evaluatedby comparing the percent slippage before surgerywith that immediately after surgery and 3 monthslater.RESULTSThe mean operation time was 175.8 min (150-200min). Blood loss was 70-200 mg, and no patientsrequired blood transfusion. In addition, there wereno surgical complications such as dural tear, caudaequina injury, nerve root injury, or deep surgicalsite infection requiring removal of the spinal im-plants. Only 1 patient had a mild infection of un-known origin 6 weeks after the surgery, in whichthe white blood cell count and C-reactive protein(CRP) level increased to 9800 cells/μL and 0.7 mg/dL, respectively. The infection required antibioticsfor 2 months ; however, it resolved without needingto remove the instrumentation. The mean JOA scorewas 15.5 before surgery and improved to 24.5 afterthe surgery.Figure 6 shows the time course of the percentslippage in each case. The slippage was reducedfrom 19.8% to 3.9% using The MESA system, andthe reduced position was maintained 3 monthslater. Figures 7 and 8 show 2 cases treated by thisprocedure. In both cases, slippage was reduced toFigure 4 : Insertion point of the CBT screw in the anteroposte-rior radiological view on the C-arm image intensifier. For theright and left CBT screw insertion, the points are at 7 o’clockand 5 o’clock of the pedicle, respectively.Figure 5 : Lateral view on the image intensifier during preparation for CBT. After drilling the insertion point in the cortex, a pedicleprobe is inserted while looking at the lateral view on the image intensifier.Y. Takata, et al. CBT-PS Hybrid390㻜㻑㻝㻜㻑㻞㻜㻑㻟㻜㻑㻑㼟㼘㼕㼜㻟㻌㼙㼛㼚㼠㼔㼟㻼㼞㼑㻙㻻㻼 㻼㼛㼟㼠㻙㻻㻼㻹㼑㼍㼚㻝㻥㻚㻤㻑㻹㼑㼍㼚㻟㻚㻥㻑㻹㼑㼍㼚㻠㻚㻡㻑㻼㼞㼑㻙㻻㻼 㻟㻹㻌㼍㼒㼠㼑㼞CBT #5  78 y.o. L4 spondylolisthesis㻼㼞㼑㻙㻻㻼 㻟㻹㻌㼍㼒㼠㼑㼞㻯㻮㼀㻌㻏㻡㻌㻌㻣㻞㼥㻚㼛㻚㻌㻸㻠㻌㼟㼜㼛㼚㼐㼥㼘㼛㼘㼕㼟㼠㼔㼑㼟㼕㼟almost the normal position, which was maintainedfor 3 months.DISCUSSIONMinimal invasiveness :In theory, the present procedure is less invasivethan conventional PS fusion surgery. At our insti-tution, conventional single-level transforaminal lum-bar interbody fusion surgery with PS requires a skinincision of around 8-10 cm, whereas this hybridCBT-PS procedure requires an incision of 5-6 cm.In terms of incision length, our technique is less in-vasive than the conventional PS technique.To understand the invasiveness to bone and mus-cle during the back surgery, CRP, creatinine kinase(CK), and interleukin-6 values have sometimesbeen evaluated (5-7). However, in this technicalnote, we need to concentrate on the technical note.Presently, we have initiated to understand its mini-mally invasiveness with evaluating these parameters.Comparison with the other minimally invasive fusiontechniques :Use of the percutaneous pedicle screwing (PPS)procedure is another option for minimally invasivefusion surgery. Although the midline skin incisionin PPS can be smaller, 2 additional skin incisions(and as many as 4) are needed. Furthermore, in thePPS procedure, the PS must pass through the para-vertebral muscles, which may damage them, al-though the CK level after surgery is reported to belower than that with the conventional PS technique(8). As a next step in examining invasiveness, weneed to compare the invasiveness of the CBT tech-nique with that of the PPS technique.Repositioning and holding power with our hybridCBT-PS technique :We applied the hybrid CBT-PS technique to pa-tients with degenerative spondylolisthesis. The meanpercent slippage was 19.8% before surgery and 3.9%after surgery, and was maintained at 4.5% at the 3-month follow up, thus indicating sufficient holdingstrength of the slipped vertebra by CBT screwing.Compared with reports of the PS system, our reduc-tion ratio using the hybrid CBT-PS technique wouldbe similar to that of the conventional PS procedure.All patients were over 50 years old, and 3 were over70 years old and likely had an osteoporotic spine.Matsukawa et al. (3) recently measured the finalFigure 6 : Time course of percent slippage in each case. Themean percent slippage was reduced with the MESA system from19.8% to 3.9% after the surgery and maintained for 3 months afterthe surgery.Figure 7 : Plain radiographs of a 78-year-old patient before and3 months after the surgery. Note the reduced position achievedwith the CBT-PS technique.Figure 8 : Plain radiographs of a 72-year-old patient before and3 months after the surgery. Note the reduced position achievedwith the CBT-PS technique.The Journal of Medical Investigation Vol. 61 August 2014 391insertional torque (IT), which is reported to be agood indicator of screw pullout strength, in the PSand CBT techniques and found that the IT of CBTwas about 2-fold that of PS. Thus, it is reasonable toregard the holding strength of the vertebral bodywith CBT screwing in our cases to be in good agree-ment with the previous biomechanical data reportedby Santoni et al. (1) and Matsukawa et al. (3).Future investigation :Santoni et al. first described the CBT techniquein 2009 (1) but reported only biomechanical notclinical data. Moreover, only a few studies have re-ported the biomechanical, clinical, and radiologicaloutcomes in actual surgical cases (3, 9). Therefore,the data on this technique are as yet limited. In thefuture, comprehensive clinical and radiologic dataare needed to clarify the efficacy of this theoreti-cally ideal and minimally invasive screwing tech-nique, which we believe has the potential to becomethe gold standard for minimally invasive spinal fu-sion surgery.REFERENCES1. Santoni BG, Hynes RA, McGilvray KC,Rodriguez-Canessa G, Lyons AS, Henson MA,Womack WJ, Puttlitz CM : Cortical bone trajec-tory for lumbar pedicle screws. Spine J 9(5) :366-73, 20092. Weinstein JN, Rydevik BL, Rauschning W :Anatomic and technical considerations of pedi-cle screw fixation. Clin Orthop Relat Res (284) :34-46, 19923. Matsukawa K, Yato Y, Kato T, Imabayashi H,Asazuma T, Nemoto K : In vivo analysis of in-sertional torque during pedicle screwing usingcortical bone trajectory technique. Spine (PhilaPa 1976) 39(4) : E240-5, 20144. Japanese Orthopaedic Association : JapaneseOrthopaedic Association Assessment CriteriaGuidelines Manual. Tokyo : JOA ; 1996 : 46-49.5. Pan L, Zhang P, Yin Q. Comparison of tissuedamages caused by endoscopic lumbar dis-cectomy and traditional lumbar discectomy :A randomised controlled trial. Int J Surg. 2014Feb 28. pii : S1743-9191(14)00054-5.6. Sasaoka R1, Nakamura H, Konishi S,Nagayama R, Suzuki E, Terai H, Takaoka K :Objective assessment of reduced invasivenessin MED. Compared with conventional one-levellaminotomy. Eur Spine J 15(5) : 577-82, 20067. Huang TJ, Hsu RW, Li YY, Cheng CC : Lesssystemic cytokine response in patients follow-ing microendoscopic versus open lumbar dis-cectomy. J Orthop Res 23(2) : 406-11, 20058. Lehmann W, Ushmaev A, Ruecker A,Nuechtern J, Grossterlinden L, Begemann PG,Baeumer T, Rueger JM, Briem D : Comparisonof open versus percutaneous pedicle screw in-sertion in a sheep model. Eur Spine J 17(6) :857-63, 20089. Matsukawa K, Yato Y, Nemoto O, ImabayashiH, Asazuma T, Nemoto K : MorphometricMeasurement of Cortical Bone Trajectory forLumbar Pedicle Screw Insertion Using Com-puted Tomography. J Spinal Disord Tech 26 :E248-E253, 2013Y. Takata, et al. CBT-PS Hybrid392

Hybrid technique of cortical bone trajectory and pedicle screwing for minimally invasive spine reconstruction surgery : A technical note

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Hybrid technique of cortical bone trajectory and pedicle screwing for minimally invasive spine reconstruction surgery : A technical note

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