Archives of Medical Research 41 (2010) 478e482 BRIEF REPORT An Expandable Prosthesis with Dual Cage-and-Plate Function in a Single Device for Vertebral Body Replacement: Clinical Experience on 14 Cases with Vertebral TumorsJuan J. Ramırez,a Erwin Chiquete,b Juan J. Ramırez, Jr.,c Ernesto Gomez-Limon,d and Juan M. Ramırezb ´ ´ ´ ´ ´ a Department of Orthopedics, bDepartment of Internal Medicine, dDepartment of Neurology and Neurosurgery, Hospital Civil de Guadalajara, Fray Antonio Alcalde, Universidad de Guadalajara, Guadalajara, Me ´xico, cUniversidad Auto ´noma de Guadalajara, Zapopan, Me ´xico Received for publication April 15, 2010; accepted August 26, 2010 (ARCMED-D-10-00174). An expandable vertebral body prosthesis with dual cage-and-plate function in a single device (JR prosthesis) was designed to test the hypothesis that this modular system can provide the biomechanical requirements for immediate and durable spine stabilization after corpectomy. Cadaver assays were performed with a stainless steal device to test ﬁxa- tion and adequacy to the human spine anatomy. Then, 14 patients with vertebral tumors (eight metastatic) underwent corpectomy and vertebral body replacement with a titanium- made JR prosthesis. All patients had neurological deﬁcit, severe pain and spine instability prior to surgery. Mean pain score before surgery on a visual analog scale decreased from 7.6e3.0 points after operation ( p 5 0.002). All patients achieved at least one grade of improvement in the Frankel score ( p 5 0.003), excepting the three patients with Frankel grade A before surgery. Two patients with renal cell carcinoma died during the following 4 days after surgery. The remaining patients attained a painless and stable spine immedi- ately, which was maintained for long periods (mean follow-up: 25.4 months). No signif- icant infections or implant failures were registered. A nonfatal case of inferior vena cava surgical injury was observed (repaired during surgery without further complications). In conclusion, the JR prosthesis stabilizes the spine immediately after surgery and for the rest of the patients’ life. To our knowledge, this is the ﬁrst report on the clinical experi- ence of any expandable vertebral body prosthesis with dual cage-and-plate function in a single device. Ó 2010 IMSS. Published by Elsevier Inc. Key Words: Cage, Corpectomy, Plate, Prosthesis, Spine, Vertebral tumor.Introduction to recreate the mechanical function by means of a number of anterior or posterior devices. In our center, until theEighty ﬁve percent of all cases of spinal metastasis are 1990s, patients with vertebral fractures or tumors werelocated primarily in the vertebral body (1). Spinal cord managed with laminectomy plus Harrington and/or Luquelesion in metastatic disease of the spine results from direct devices (1,3). Most patients reported that their pain wastumor compression, vertebral body collapse and retropulsed not alleviated and the neurological deﬁcit almost alwaysbone fragments (2). As a result, pain, neurological deﬁcit, ´ persisted. In 1995, one of the authors (J.J. Ramırez) de-spine instability or segmental deformities ensue (1,2). In signed an expandable vertebral body prosthesis (namedorder to restore the stability of the spine, it is necessary the JR prosthesis) to be used for spinal stabilization after corpectomy. To the best of our knowledge, the JR prosthesis is the ﬁrst with dual plate-and-cage function in a single ´ ´ ´ Address reprint requests to: Dr. Juan Jose Ramırez Jimenez, Servicio device (4). Here we describe the characteristics of the JRde Ortopedia, Hospital Civil de Guadalajara Fray Antonio Alcalde, ´Hospital 278, Col. El Retiro, C.P. 44280 Guadalajara, Jalisco, Mexico; prosthesis and the clinical experience with 14 patients withPhone: (þ52) (33) 3613-3951; FAX: (þ52) (33) 3613-3951; E-mail: vertebral tumors who underwent corpectomy and firstname.lastname@example.org ment of the vertebral body with this implant.0188-4409/$ - see front matter. Copyright Ó 2010 IMSS. Published by Elsevier Inc.doi: 10.1016/j.arcmed.2010.08.013
Expandable Plate-and-Cage Prosthesis for Spine Stabilization after Corpectomy 479Materials and MethodsProsthesis DesignThe vertebral bodies excepting C1 and C2 were measuredin appropriate adult cadaver preparations of the Departmentof Anatomy of the Universidad de Guadalajara, Mexico.After anatomic studies and measurements of the lumbarand thoracic vertebrae, drafts were performed and wax-and-plaster prosthesis models were created accordingly.Using the lost-wax casting method, a chromium-cobaltprototype was created and later was modiﬁed to an expand-able stainless steel model, which ﬁnally resulted in a tita-nium device. The JR prosthesis (U.S. Pat. No. 5,458,641)has ﬁve components: a) cephalad, b) caudad, c) centralcylinder, d) anti-rotational guide bolt, and e) ﬁxation screw(Figure 1A, left). Its components, once assembled, workwell together to create a modular and expandable cage-and-plate device. The cephalad and caudad componentshave three elements: 1) horizontal; 2) vertical; and 3)central (Figure 1A, left). The horizontal elements of boththe caudad and cephalad components have conical projec-tions in their sustentation surface in order to enhanceﬁxation and to avoid shearing between the implant andthe vertebral body. These horizontal elements also havea centered hole, which continues distally in the cephaladcomponent and proximately in the caudad component tocreate a cylindrical cage that can support bone grafts inside.The central elements of both the cephalad and caudadcomponents have an external thread in such a way that byrotating the central cylinder (component C) in a clockwisedirection the components move away from each other. Toavoid great vessel injury, the vertical element is located atthe patient’s right side for the upper and mid-thoracicregions and at the left side for the lower thoracic andlumbar spine. The vertical element of the cephalad compo-nent has a hole in the lower aspect and in the caudadcomponent on the higher part in order to lodge an anti-rotational guide bolt (Figure 1A, right). This modular,anatomic and expandable design allows that, with littlechanges, the cage-and-plate prosthesis can be used for allvertebral bodies with exception of C1 and C2 (Figures 1B Figure 1. (A) Components: a) cephalad, b) caudad, c) central cylinder, d)and 1C). Due to its characteristic design, its anterior loca- anti-rotational guide bolt, and e) ﬁxation screw and elements: 1) hori-tion to the instantaneous axis of rotation and its cage-and- zontal, 2) central, and 3) vertical of the JR prosthesis. On the right sideplate function, the prosthesis offers crossed and opposed of panel (A) a thoracolumbar JR device diagram is shown. (B) Cervical JR device. (C) L5 JR device. (D) The case of a 46-year-old female withvectors to the ﬂexion, extension and rotation moments of plasmacytoma affecting T12 (left). Postoperative radiograph showing thethe spine. The cross-sectional area of both the cephalad application of the JR prosthesis (right). (A color ﬁgure can be found inand caudad components are approximately equal to that the online version of this article.)of the vertebral end plates. by an antero-lateral and retroperitoneal left approach. The T12-L1 and L2eL3 discs and the L1 and L2 vertebralCadaver Assays bodies were removed by using osteotomes and rongeur.The prosthesis was implanted into a cadaver donated by the After vertebral body removal, the implant was placed inDepartment of Anatomy of our University. This cadaver the corpectomy site and the prosthesis was expanded byhad the L1 and L2 vertebral bodies removed, which were rotating the central cylinder with a lever bar until compres-replaced with a prototypic implant. The spine was exposed sion was applied to the end plates of T12 and L3 vertebral
480 Ramı´rez et al./ Archives of Medical Research 41 (2010) 478e482Table 1. General characteristics of the patients who received vertebral body replacement with the JR prosthesis Follow-up Frankel grade VAS pain gradeCase Age/sex Diagnosis Spine level Approach (months) Pre/postoperatively Pre/postoperatively Complications1 24/M Plasmacytoma T11 AL/Left 84 A/A 8/3 None2 61/M Adenocarcinoma T11 AL/Left 6 A/A 9/3 None3 72/M Renal carcinoma L3 AL/Left 0 A/NA 8/NA Massive bleeding during surgery causing death4 35/F Cervical cancer L2 AL/Left 6 C/D 8/3 None5 28/M Plasmacytoma T8 AL/Left 60 C/E 5/2 Atelectasis6 50/F Thyroid cancer L3 AL/Left 96 D/E 8/3 Vena cava lesion7 46/F Cervical cancer L1e2 AL/Left 9 C/E 7/4 None8 11/M Osteosarcoma T8 AL/Right 11 C/D 8/5 None9 10/M Osteosarcoma T8e9 AL/Left and P 48 C/E 7/4 None10 44/M Renal carcinoma L3 AL/Left 7 C/D 9/4 None11 42/F Plasmacytoma T12 AL/Left 16 C/D 8/3 None12 62/M Renal carcinoma L3 AL/Left 0 C/NA 8/NA Renal failure 4 days after surgery causing death13 56/M Hemangioma T11 AL/Left 9 C/E 6/1 None14 52/F Breast cancer T11 AL/Left 4 C/E 8/2 NoneAL, antero-lateral; F, female; L, left; M, male; NA, not applicable; P, posterior; R, right; VAS, visual analog scale.bodies. The prosthesis was ﬁxated to T12 and L3 with two Statistical Analysisscrews (length: 6.5 mm). With a hook attached directly to Descriptive statistics were analyzed as simple frequenciesthe prosthesis, the cadaver was raised until completely for nominal variables and as means for continuous vari-hanged. While suspended, radiographs were taken at the ables. Wilcoxon’s signed rank test for paired relatedsite of the corpectomy. Later, the body was taken down samples was used to compare scores of visual analog scaleand subjected to ﬂexion, rotation and extension forces by (VAS) and Frankel scale before and after surgery. Allsix research collaborators while observing the implant’s p values !0.05 were considered signiﬁcant. SPSS v.17.0behavior in situ. statistical package was used for all calculations.Trial on Patients ResultsFrom March 1995eDecember 2007, 14 patients with verte-bral tumors underwent corpectomy and vertebral body We studied 14 patients (nine males, mean age: 42.4 years,replacement with the JR prosthesis in our center: at one range: 10e72 years) with vertebral tumors. Of the 14level for 12 patients and at two different spine levels in tumors, three were plasmacytomas, two osteosarcomas,the other two patients. The ethics committee of our hospital one hemangioma and eight metastatic tumors: three renalapproved this study. The main inclusion criteria for corpec- carcinomas, one thyroid carcinoma, two cervical cancers,tomy and vertebral body replacement were severe pain, one breast cancer and one adenocarcinoma of primaryneurological deﬁcit, spinal instability and having a medical unknown (Table 1). Mean surgical time was 242 minstatus suitable for surgery. The patient was placed in the (range: 210e360 min). Pain improved from a mean VASlateral decubitus position. The spine was exposed one of 7.6 preoperatively to 3.0 after surgery in the 12 patientssegment above and one segment below the injured vertebra. who were alive within 2 weeks postoperatively ( p 5The adjacent discs were removed and then the tumorous 0.002). This improvement in VAS was maintained to thevertebra was initially excised using osteotomes and ron- last follow-up evaluation, excepting in two patients withgeur. All retropulsed tumor fragments were excised with tumor relapse. Indeed, neurological deﬁcit did not improvea curette. The implant was placed and the central sleeve in patients with Frankel A score but did change satisfacto-was rotated counterclockwise to expand the prosthesis. rily by one or two grades in patients with Frankel C or DBy this manner, kyphosis was corrected and soft tissue presurgery (no cases with Frankel B were observed) ( p 5tension was achieved. A ﬂuoroscopic view was performed 0.003). Spine stability was immediately reached in allat this time to evaluate device orientation. Once the expan- cases. All patients achieved mobility or could be movedsion was completed and the orientation of the device satis- 48e72 h postoperatively, which facilitated nursing care.factory, it was ﬁxated laterally with two screws above and The need for analgesics for postoperative pain managementtwo screws below located in the vertical device’s elements, was minimal. Complications related to the surgical eventforming the expandable lateral plate. included mild inferior vena cava lesion in one case
Expandable Plate-and-Cage Prosthesis for Spine Stabilization after Corpectomy 481(repaired without further complications) and pulmonary mechanically stable if only one or two columns areatelectasis in two patients who underwent thoracotomy, destroyed but instable if there are three or more. The JRnecessitating a chest tube for lung re-expansion. Excluding prosthesis provides mechanical stability because it restorestwo patients who died perioperatively, minimal survival the Holdsworth’s anterior column, the Denis’ anterior andlength was 6 months with a maximum of 8 years (mean middle columns and the four Kostuik’s anterior columns.follow-up period: 25.4 months). Three out of 14 patients Based on White and Panjabi’s concept (12), the JR pros-are currently alive: one with plasmacytoma, one with osteo- thesis also provides clinical stability because it avoidssarcoma and one with a spinal hemangioma. The patient with displacement by offering opposed and crossed vectors toosteosarcoma (Frankel grade C preoperatively) who is still the main deforming forces of the spine so as not to damagealive 5 years after corpectomy of two levels also received or irritate the spinal cord or nerve roots.a posterior instrumentation with Luque rod because the A number of expandable devices exist (13,14), and theirposterior spinal elements were also removed. This patient utility has been proven in vertebral tumors (15), demon-walked without pain (Frankel grade E postoperatively). strating that spinal stability can be attained immediatelyTwo out of three patients with metastases from renal cancer and that it represents a sufﬁcient procedure in spinal tumordied perioperatively: one during surgery due to massive surgery (15). Expandable implants are preferred over tradi-bleeding, and the other patient 4 days after surgery due to tional devices, and it is possible that variations in cagerenal failure. The third patient with renal cell carcinoma died design are of little importance in terms of effectiveness7 months after surgery due to cancer complications. The (16). Cages were created to provide mechanical supportpatient with metastasis from thyroid cancer (a 50-year-old after corpectomy (5,6,8,17,18). However, cages were notfemale) has the longest survival (8 years) of our cohort. designed as stand-alone devices because the constructionShe ﬁnally presented lumbar pain and lower limb weakness is instable in rotation. Therefore, a lateral plate is neededdue to local relapse and died in a second surgery (posterior to control rotational moment (11e19).instrumentation and laminectomy) due to pulmonary embo- This is a rather small cohort on the experience with thislism. Of the immediate survivors, the patient with the short- implant in patients with vertebral tumors, which representsest survival (6 months) had an adenocarcinoma from an only a subset of all cases in whom the JR prosthesis hasunknown primary. Regarding the patients with plasmacyto- been used in our hospital. The experience according toma, one out of three is currently alive. The other two patients other indications for vertebral body replacement (e.g.,died after 6 and 7 years postsurgery, respectively. There have trauma, posttraumatic kyphosis, Pott’s disease) with thebeen no implant failures, screw fractures or the need for pros- implant will be reported shortly. The design of the JRthesis removal in any case. Spinal stability was maintained prosthesis makes its placement easy and with remarkablefor the rest of the patients’ life (Figure 1D). duration. This ﬁrst communication should be considered hypothesis-generating work waiting for systematic conﬁr- mation or for the test of time.DiscussionWith modern devices, few complications associated withanterior implants are reported (5e7); however, these Acknowledgmentsinclude screw and bolt fractures as well as loss of reduction ´ ´ Dr. Juan Jose Ramırez is the inventor of the JR Prosthesis (US Pat.and progressive kyphosis. Kaneda (8) reported that the most No. 5,458,641) without any commercial relationship with externalcommon complications with anterior instrumentations are parts. The authors are indebted to Dr. Fernando Hiramuro-Hirotani (Chief, Orthopedics Department), Dr. Luis Navarro-Rodrıguez ´accidental sympathectomy (10%), subclinical pseudoarth- (Former Chief, Orthopedics Department), Dr. Jaime Agustın ´rosis (7%) and implant failure (7%). Here we conﬁrmed ´ ´ Gonzalez-Alvarez (General Director, OPD Hospital Civil dethe hypothesis that the biomechanical features of the JR ´ ´ Guadalajara), Dr. Antonio Luevanos-Velazquez (Education andprosthesis provide spinal stability for the patient’s lifespan, Research Director, OPD Hospital Civil de Guadalajara), Dr.and no implant failures or fractures were observed. ´ ´ ´ Martın Gomez and Dr. Sergio Sanchez (Department of ThoracicHowever, it is necessary to note that the concept of spinal Surgery), as well as the Department of Anatomy of the Universi-stability is rather subjective, except in cases of overt dad de Guadalajara for the support provided for this work. Thekyphosis or translation. According to Holdsworth (9), authors would like to thank the patients and their families for theirspinal stability depends on the integrity of the posterior os- trust and endurance in this endeavor.teoligamentary complex. Denis (10) further divided theHoldsworth’s anterior column in anterior and middle andsuggested that spinal stability depends on the integrity of References 1. Heller JG, Pedlow FX. Tumors of the spine. In: Garﬁn SR,two columns. Kostuik et al. (11) based their model of Vaccaro AR, eds. Orthopedic Knowledge Update: Spine. Rosemont,stability on Denis’ concept by dividing the spinal columns IL: AAOS; 1997. pp. 989e999.in two further halves (obtaining six columns: three lefts and 2. Harrigton KD. Metastatic disease of the spine. J Bone Joint Surg Amthree rights). According to this model, the spine will be 1986;68:1110e1115.
482 Ramı´rez et al./ Archives of Medical Research 41 (2010) 478e482 3. Luque ER. The anatomic basis and the development of segmental 12. White AA III, Panjabi MM. Clinical Biomechanics of the Spine. 2nd spine instrumentation. Spine 1982;7:256e259. ed. Philadelphia: Lippincott Williams & Wilkins; 1990. ´ ´ 4. Ramırez JJ, Chiquete E, Ramırez S, et al. JR vertebral body prosthesis: 13. Reinhold M, Schmoelz W, Canto F, et al. A new distractable implant a modular, anatomical and expandable device, with cage function and for vertebral body replacement: biomechanical testing of four implants plate dual designed ad hoc for spine stabilization after corpectomy. for the thoracolumbar spine. Arch Orthop Trauma Surg 2009;129: Coluna/Columna 2009;8:178e186. 1375e1382. 5. Carl AL, Roger DJ. Advances in spinal instrumentation: a review 14. Uchida K, Kobayashi S, Nakajima H, et al. Anterior expandable strut article. Semin Spine Surg 1997;9:204e226. cage replacement for osteoporotic thoracolumbar vertebral collapse. 6. Auguste KI, Chin C, Acosta FL, et al. Expandable cylindrical cages in the J Neurosurg Spine 2006;4:454e462. cervical spine: a review of 22 cases. J Neurosurg Spine 2006;4:285e291. 15. Ernstberger T, Kogel M, Konig F, et al. Expandable vertebral body ¨ ¨ 7. Steinmetz MP, Mekhail A, Benzel EC. Management of metastatic replacement in patients with thoracolumbar spine tumors. Arch Orthop tumors of the spine: strategies and operative indications. Neurosurg Trauma Surg 2005;125:660e669. Focus 2001;11:e2. 16. Pﬂugmacher R, Schleicher P, Schaefer J, et al. Biomechanical compar- 8. Kaneda K, Taneichi H, Abumi K, et al. Anterior decompression and ison of expandable cages for vertebral body replacement in the stabilization with the Kaneda device for thoracolumbar burst fractures thoracolumbar spine. Spine (Phila Pa 1976) 2004;29:1413e1419. associated with neurological deﬁcits. J Bone Joint Surg Am 1997;79: 17. Chou D, Lu DC, Weinstein P, et al. Adjacent-level vertebral body frac- 69e83. tures after expandable cage reconstruction. J Neurosurg Spine 2008;8: 9. Holdsworth F. Fractures, dislocations and fracture-dislocations of the 584e588. spine. J Bone Joint Surg Am 1970;52:1534e1551. 18. Payer M. Implantation of a distractible titanium cage after cervical10. Denis F. The three column spine and signiﬁcance in the classiﬁcation corpectomy: technical experience in 20 consecutive cases. Acta of acute thoracolumbar spine injuries. Spine 1983;8:817e827. Neurochir (Wien) 2006;148:1173e1180.11. Kostuik JP. Anterior ﬁxation for burst fractures of the thoracic and 19. Thongtrangan I, Balabhadra RS, Le H, et al. Vertebral body replace- lumbar spine with or without neurological involvement. Spine 1988; ment with an expandable cage for reconstruction after spinal tumor 13:286e293. resection. Neurosurg Focus 2003;15:e8.