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An Expandable Prosthesis with Dual Cage-and-Plate Function in a Single Device for Vertebral Body Replacement: Clinical Experience on 14 Cases with Vertebral Tumors
 

An Expandable Prosthesis with Dual Cage-and-Plate Function in a Single Device for Vertebral Body Replacement: Clinical Experience on 14 Cases with Vertebral Tumors

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Juan J. Ramı´rez, Erwin Chiquete, Juan J. Ramı´rez, Jr., Ernesto Go´mez-Limo´n, and Juan M. Ramı´rez ...

Juan J. Ramı´rez, Erwin Chiquete, Juan J. Ramı´rez, Jr., Ernesto Go´mez-Limo´n, and Juan M. Ramı´rez

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 fixation
and adequacy to the human spine anatomy. Then, 14 patients with vertebral tumors
(eight metastatic) underwent corpectomy and vertebral body replacement with a titaniummade
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 immediately,
which was maintained for long periods (mean follow-up: 25.4 months). No significant
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 experience
of any expandable vertebral body prosthesis with dual cage-and-plate function in
a single device.

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    An Expandable Prosthesis with Dual Cage-and-Plate Function in a Single Device for Vertebral Body Replacement: Clinical Experience on 14 Cases with Vertebral Tumors An Expandable Prosthesis with Dual Cage-and-Plate Function in a Single Device for Vertebral Body Replacement: Clinical Experience on 14 Cases with Vertebral Tumors Document Transcript

    • 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 Tumors ´ ´ ´ ´ ´ Juan 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 ´noma de ´xico, cUniversidad Auto de Guadalajara, Fray Antonio Alcalde, Universidad de Guadalajara, Guadalajara, Me ´xico Guadalajara, Zapopan, Me 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 fixation and adequacy to the human spine anatomy. Then, 14 patients with vertebral tumors (eight metastatic) underwent corpectomy and vertebral body replacement with a titaniummade 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 immediately, which was maintained for long periods (mean follow-up: 25.4 months). No significant 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 experience 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 Eighty five percent of all cases of spinal metastasis are located primarily in the vertebral body (1). Spinal cord lesion in metastatic disease of the spine results from direct tumor compression, vertebral body collapse and retropulsed bone fragments (2). As a result, pain, neurological deficit, spine instability or segmental deformities ensue (1,2). In order to restore the stability of the spine, it is necessary ´ ´ ´ Address reprint requests to: Dr. Juan Jose Ramırez Jimenez, Servicio de Ortopedia, Hospital Civil de Guadalajara Fray Antonio Alcalde, ´ Hospital 278, Col. El Retiro, C.P. 44280 Guadalajara, Jalisco, Mexico; Phone: (þ52) (33) 3613-3951; FAX: (þ52) (33) 3613-3951; E-mail: rajj0709@hotmail.com to recreate the mechanical function by means of a number of anterior or posterior devices. In our center, until the 1990s, patients with vertebral fractures or tumors were managed with laminectomy plus Harrington and/or Luque devices (1,3). Most patients reported that their pain was not alleviated and the neurological deficit almost always ´ persisted. In 1995, one of the authors (J.J. Ramırez) designed an expandable vertebral body prosthesis (named 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 device (4). Here we describe the characteristics of the JR prosthesis and the clinical experience with 14 patients with vertebral tumors who underwent corpectomy and replacement 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 479 Materials and Methods Prosthesis Design The vertebral bodies excepting C1 and C2 were measured in appropriate adult cadaver preparations of the Department of Anatomy of the Universidad de Guadalajara, Mexico. After anatomic studies and measurements of the lumbar and thoracic vertebrae, drafts were performed and waxand-plaster prosthesis models were created accordingly. Using the lost-wax casting method, a chromium-cobalt prototype was created and later was modified to an expandable stainless steel model, which finally resulted in a titanium device. The JR prosthesis (U.S. Pat. No. 5,458,641) has five components: a) cephalad, b) caudad, c) central cylinder, d) anti-rotational guide bolt, and e) fixation screw (Figure 1A, left). Its components, once assembled, work well together to create a modular and expandable cageand-plate device. The cephalad and caudad components have three elements: 1) horizontal; 2) vertical; and 3) central (Figure 1A, left). The horizontal elements of both the caudad and cephalad components have conical projections in their sustentation surface in order to enhance fixation and to avoid shearing between the implant and the vertebral body. These horizontal elements also have a centered hole, which continues distally in the cephalad component and proximately in the caudad component to create a cylindrical cage that can support bone grafts inside. The central elements of both the cephalad and caudad components have an external thread in such a way that by rotating the central cylinder (component C) in a clockwise direction the components move away from each other. To avoid great vessel injury, the vertical element is located at the patient’s right side for the upper and mid-thoracic regions and at the left side for the lower thoracic and lumbar spine. The vertical element of the cephalad component has a hole in the lower aspect and in the caudad component on the higher part in order to lodge an antirotational guide bolt (Figure 1A, right). This modular, anatomic and expandable design allows that, with little changes, the cage-and-plate prosthesis can be used for all vertebral bodies with exception of C1 and C2 (Figures 1B and 1C). Due to its characteristic design, its anterior location to the instantaneous axis of rotation and its cage-andplate function, the prosthesis offers crossed and opposed vectors to the flexion, extension and rotation moments of the spine. The cross-sectional area of both the cephalad and caudad components are approximately equal to that of the vertebral end plates. Cadaver Assays The prosthesis was implanted into a cadaver donated by the Department of Anatomy of our University. This cadaver had the L1 and L2 vertebral bodies removed, which were replaced with a prototypic implant. The spine was exposed Figure 1. (A) Components: a) cephalad, b) caudad, c) central cylinder, d) anti-rotational guide bolt, and e) fixation screw and elements: 1) horizontal, 2) central, and 3) vertical of the JR prosthesis. On the right side 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 with plasmacytoma affecting T12 (left). Postoperative radiograph showing the application of the JR prosthesis (right). (A color figure can be found in the online version of this article.) by an antero-lateral and retroperitoneal left approach. The T12-L1 and L2eL3 discs and the L1 and L2 vertebral bodies were removed by using osteotomes and rongeur. After vertebral body removal, the implant was placed in the corpectomy site and the prosthesis was expanded by rotating the central cylinder with a lever bar until compression was applied to the end plates of T12 and L3 vertebral
    • 480 Ramı´rez et al./ Archives of Medical Research 41 (2010) 478e482 Table 1. General characteristics of the patients who received vertebral body replacement with the JR prosthesis Case Age/sex Diagnosis Spine level 1 2 3 24/M 61/M 72/M Plasmacytoma Adenocarcinoma Renal carcinoma T11 T11 L3 4 5 6 7 8 9 10 11 12 35/F 28/M 50/F 46/F 11/M 10/M 44/M 42/F 62/M Cervical cancer Plasmacytoma Thyroid cancer Cervical cancer Osteosarcoma Osteosarcoma Renal carcinoma Plasmacytoma Renal carcinoma L2 T8 L3 L1e2 T8 T8e9 L3 T12 L3 13 14 56/M 52/F Hemangioma Breast cancer T11 T11 Follow-up (months) Frankel grade Pre/postoperatively VAS pain grade Pre/postoperatively AL/Left AL/Left AL/Left 84 6 0 A/A A/A A/NA 8/3 9/3 8/NA AL/Left AL/Left AL/Left AL/Left AL/Right AL/Left and P AL/Left AL/Left AL/Left 6 60 96 9 11 48 7 16 0 C/D C/E D/E C/E C/D C/E C/D C/D C/NA 8/3 5/2 8/3 7/4 8/5 7/4 9/4 8/3 8/NA 9 4 C/E C/E Approach AL/Left AL/Left 6/1 8/2 Complications None None Massive bleeding during surgery causing death None Atelectasis Vena cava lesion None None None None None Renal failure 4 days after surgery causing death None None AL, 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 screws (length: 6.5 mm). With a hook attached directly to the prosthesis, the cadaver was raised until completely hanged. While suspended, radiographs were taken at the site of the corpectomy. Later, the body was taken down and subjected to flexion, rotation and extension forces by six research collaborators while observing the implant’s behavior in situ. Statistical Analysis Descriptive statistics were analyzed as simple frequencies for nominal variables and as means for continuous variables. Wilcoxon’s signed rank test for paired related samples was used to compare scores of visual analog scale (VAS) and Frankel scale before and after surgery. All p values !0.05 were considered significant. SPSS v.17.0 statistical package was used for all calculations. Trial on Patients From March 1995eDecember 2007, 14 patients with vertebral tumors underwent corpectomy and vertebral body replacement with the JR prosthesis in our center: at one level for 12 patients and at two different spine levels in the other two patients. The ethics committee of our hospital approved this study. The main inclusion criteria for corpectomy and vertebral body replacement were severe pain, neurological deficit, spinal instability and having a medical status suitable for surgery. The patient was placed in the lateral decubitus position. The spine was exposed one segment above and one segment below the injured vertebra. The adjacent discs were removed and then the tumorous vertebra was initially excised using osteotomes and rongeur. All retropulsed tumor fragments were excised with a curette. The implant was placed and the central sleeve was rotated counterclockwise to expand the prosthesis. By this manner, kyphosis was corrected and soft tissue tension was achieved. A fluoroscopic view was performed at this time to evaluate device orientation. Once the expansion was completed and the orientation of the device satisfactory, it was fixated laterally with two screws above and two screws below located in the vertical device’s elements, forming the expandable lateral plate. Results We studied 14 patients (nine males, mean age: 42.4 years, range: 10e72 years) with vertebral tumors. Of the 14 tumors, three were plasmacytomas, two osteosarcomas, one hemangioma and eight metastatic tumors: three renal carcinomas, one thyroid carcinoma, two cervical cancers, one breast cancer and one adenocarcinoma of primary unknown (Table 1). Mean surgical time was 242 min (range: 210e360 min). Pain improved from a mean VAS of 7.6 preoperatively to 3.0 after surgery in the 12 patients who were alive within 2 weeks postoperatively ( p 5 0.002). This improvement in VAS was maintained to the last follow-up evaluation, excepting in two patients with tumor relapse. Indeed, neurological deficit did not improve in patients with Frankel A score but did change satisfactorily by one or two grades in patients with Frankel C or D presurgery (no cases with Frankel B were observed) ( p 5 0.003). Spine stability was immediately reached in all cases. All patients achieved mobility or could be moved 48e72 h postoperatively, which facilitated nursing care. The need for analgesics for postoperative pain management was minimal. Complications related to the surgical event included mild inferior vena cava lesion in one case
    • Expandable Plate-and-Cage Prosthesis for Spine Stabilization after Corpectomy (repaired without further complications) and pulmonary atelectasis in two patients who underwent thoracotomy, necessitating a chest tube for lung re-expansion. Excluding two patients who died perioperatively, minimal survival length was 6 months with a maximum of 8 years (mean follow-up period: 25.4 months). Three out of 14 patients are currently alive: one with plasmacytoma, one with osteosarcoma and one with a spinal hemangioma. The patient with osteosarcoma (Frankel grade C preoperatively) who is still alive 5 years after corpectomy of two levels also received a posterior instrumentation with Luque rod because the posterior spinal elements were also removed. This patient walked without pain (Frankel grade E postoperatively). Two out of three patients with metastases from renal cancer died perioperatively: one during surgery due to massive bleeding, and the other patient 4 days after surgery due to renal failure. The third patient with renal cell carcinoma died 7 months after surgery due to cancer complications. The patient with metastasis from thyroid cancer (a 50-year-old female) has the longest survival (8 years) of our cohort. She finally presented lumbar pain and lower limb weakness due to local relapse and died in a second surgery (posterior instrumentation and laminectomy) due to pulmonary embolism. Of the immediate survivors, the patient with the shortest survival (6 months) had an adenocarcinoma from an unknown primary. Regarding the patients with plasmacytoma, one out of three is currently alive. The other two patients died after 6 and 7 years postsurgery, respectively. There have been no implant failures, screw fractures or the need for prosthesis removal in any case. Spinal stability was maintained for the rest of the patients’ life (Figure 1D). Discussion With modern devices, few complications associated with anterior implants are reported (5e7); however, these include screw and bolt fractures as well as loss of reduction and progressive kyphosis. Kaneda (8) reported that the most common complications with anterior instrumentations are accidental sympathectomy (10%), subclinical pseudoarthrosis (7%) and implant failure (7%). Here we confirmed the hypothesis that the biomechanical features of the JR prosthesis provide spinal stability for the patient’s lifespan, and no implant failures or fractures were observed. However, it is necessary to note that the concept of spinal stability is rather subjective, except in cases of overt kyphosis or translation. According to Holdsworth (9), spinal stability depends on the integrity of the posterior osteoligamentary complex. Denis (10) further divided the Holdsworth’s anterior column in anterior and middle and suggested that spinal stability depends on the integrity of two columns. Kostuik et al. (11) based their model of stability on Denis’ concept by dividing the spinal columns in two further halves (obtaining six columns: three lefts and three rights). According to this model, the spine will be 481 mechanically stable if only one or two columns are destroyed but instable if there are three or more. The JR prosthesis provides mechanical stability because it restores the Holdsworth’s anterior column, the Denis’ anterior and middle columns and the four Kostuik’s anterior columns. Based on White and Panjabi’s concept (12), the JR prosthesis also provides clinical stability because it avoids displacement by offering opposed and crossed vectors to the main deforming forces of the spine so as not to damage or irritate the spinal cord or nerve roots. A number of expandable devices exist (13,14), and their utility has been proven in vertebral tumors (15), demonstrating that spinal stability can be attained immediately and that it represents a sufficient procedure in spinal tumor surgery (15). Expandable implants are preferred over traditional devices, and it is possible that variations in cage design are of little importance in terms of effectiveness (16). Cages were created to provide mechanical support after corpectomy (5,6,8,17,18). However, cages were not designed as stand-alone devices because the construction is instable in rotation. Therefore, a lateral plate is needed to control rotational moment (11e19). This is a rather small cohort on the experience with this implant in patients with vertebral tumors, which represents only a subset of all cases in whom the JR prosthesis has been used in our hospital. The experience according to other indications for vertebral body replacement (e.g., trauma, posttraumatic kyphosis, Pott’s disease) with the implant will be reported shortly. The design of the JR prosthesis makes its placement easy and with remarkable duration. This first communication should be considered hypothesis-generating work waiting for systematic confirmation or for the test of time. Acknowledgments ´ ´ Dr. Juan Jose Ramırez is the inventor of the JR Prosthesis (US Pat. No. 5,458,641) without any commercial relationship with external parts. The authors are indebted to Dr. Fernando Hiramuro-Hirotani ´ (Chief, Orthopedics Department), Dr. Luis Navarro-Rodrıguez ´ (Former Chief, Orthopedics Department), Dr. Jaime Agustın ´ ´ Gonzalez-Alvarez (General Director, OPD Hospital Civil de ´ ´ Guadalajara), Dr. Antonio Luevanos-Velazquez (Education and Research Director, OPD Hospital Civil de Guadalajara), Dr. ´ ´ ´ Martın Gomez and Dr. Sergio Sanchez (Department of Thoracic Surgery), as well as the Department of Anatomy of the Universidad de Guadalajara for the support provided for this work. The authors would like to thank the patients and their families for their trust and endurance in this endeavor. References 1. Heller JG, Pedlow FX. Tumors of the spine. In: Garfin SR, Vaccaro AR, eds. Orthopedic Knowledge Update: Spine. Rosemont, IL: AAOS; 1997. pp. 989e999. 2. Harrigton KD. Metastatic disease of the spine. J Bone Joint Surg Am 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 spine instrumentation. Spine 1982;7:256e259. ´ ´ 4. Ramırez JJ, Chiquete E, Ramırez S, et al. JR vertebral body prosthesis: a modular, anatomical and expandable device, with cage function and plate dual designed ad hoc for spine stabilization after corpectomy. Coluna/Columna 2009;8:178e186. 5. Carl AL, Roger DJ. Advances in spinal instrumentation: a review article. Semin Spine Surg 1997;9:204e226. 6. Auguste KI, Chin C, Acosta FL, et al. Expandable cylindrical cages in the cervical spine: a review of 22 cases. J Neurosurg Spine 2006;4:285e291. 7. Steinmetz MP, Mekhail A, Benzel EC. Management of metastatic tumors of the spine: strategies and operative indications. Neurosurg Focus 2001;11:e2. 8. Kaneda K, Taneichi H, Abumi K, et al. Anterior decompression and stabilization with the Kaneda device for thoracolumbar burst fractures associated with neurological deficits. J Bone Joint Surg Am 1997;79: 69e83. 9. Holdsworth F. Fractures, dislocations and fracture-dislocations of the spine. J Bone Joint Surg Am 1970;52:1534e1551. 10. Denis F. The three column spine and significance in the classification of acute thoracolumbar spine injuries. Spine 1983;8:817e827. 11. Kostuik JP. Anterior fixation for burst fractures of the thoracic and lumbar spine with or without neurological involvement. Spine 1988; 13:286e293. 12. White AA III, Panjabi MM. Clinical Biomechanics of the Spine. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 1990. 13. Reinhold M, Schmoelz W, Canto F, et al. A new distractable implant for vertebral body replacement: biomechanical testing of four implants for the thoracolumbar spine. Arch Orthop Trauma Surg 2009;129: 1375e1382. 14. Uchida K, Kobayashi S, Nakajima H, et al. Anterior expandable strut cage replacement for osteoporotic thoracolumbar vertebral collapse. J Neurosurg Spine 2006;4:454e462. 15. Ernstberger T, Kogel M, Konig F, et al. Expandable vertebral body ¨ ¨ replacement in patients with thoracolumbar spine tumors. Arch Orthop Trauma Surg 2005;125:660e669. 16. Pflugmacher R, Schleicher P, Schaefer J, et al. Biomechanical comparison of expandable cages for vertebral body replacement in the thoracolumbar spine. Spine (Phila Pa 1976) 2004;29:1413e1419. 17. Chou D, Lu DC, Weinstein P, et al. Adjacent-level vertebral body fractures after expandable cage reconstruction. J Neurosurg Spine 2008;8: 584e588. 18. Payer M. Implantation of a distractible titanium cage after cervical corpectomy: technical experience in 20 consecutive cases. Acta Neurochir (Wien) 2006;148:1173e1180. 19. Thongtrangan I, Balabhadra RS, Le H, et al. Vertebral body replacement with an expandable cage for reconstruction after spinal tumor resection. Neurosurg Focus 2003;15:e8.