Anterior Cervical Fusion Using Caspar Plating: Analysis of Results and Review of the Literature

Anterior Cervical Fusion Using Caspar Plating: Analysis of Results and Review of the Literature

Spine Anterior Cervical Fusion Using Caspar Plating: Analysis of Results and Review of the Literature Bikash Bose, M.D., F.A.C.S. Christiana Hospital...

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Anterior Cervical Fusion Using Caspar Plating: Analysis of Results and Review of the Literature Bikash Bose, M.D., F.A.C.S. Christiana Hospital, Medical Center of Delaware, Newark, Delaware, and Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania

Bose B. Anterior cervical fusion using Caspar plating: analysis of results and review of the literature. Surg Neurol 1998;49:25–31. BACKGROUND

Ninety-seven patients underwent anterior cervical fusions after discectomy and/or corpectomy. Fibular allograft was used in 13 cases and iliac crest was used in the remaining 84 patients.

was circumvented by using the bigger (rescue) screws at the inferior end of long constructs. © 1998 by Elsevier Science Inc. KEY WORDS

Anterior cervical fusion, Caspar plating, complications, fusion rates.

METHODS

Lateral cervical spine X-rays were reviewed for evaluation of fusion and instrumentation failures. RESULTS

Solid fusion was achieved in all but two patients (97.91%). Nineteen patients developed instrumentation related failures. Seven patients developed fracture of one screw each (one superior and six inferior). Ten patients developed screw back out (inferior screw) and in one patient the superior screws were found to be 2 mm posterior to the posterior cortex but did not cause any neurological deficits. Seven of these patients underwent revision surgery. No complications related to the instrumentation were encountered in the last 34 cases. There were no infections in this series. Five patients developed temporary dysphagia. Two developed temporary deltoid weakness and three patients developed transient recurrent laryngeal nerve palsy. One developed acute airway obstruction but the patient had a pre-existing epiglottic anomaly and sleep apnea disorder. CONCLUSIONS

In selected cases, the Caspar plating system affords an effective means of improving the fusion rate (97.91%) with acceptable instrumentation-related morbidity that improves with experience, (10.7% in the first 38 cases and 1.69% in the last 59 with an overall rate of 7.2%). Temporary neurological deficits seen in this series were probably not related to the Caspar plating procedure itself. Intraoperative fluoroscopic films can be misleading. Therefore regular lateral cervical spine X-rays postplating in the operating room prior to closure are recommended. Lower screws backed out in all failures and this

Address reprint requests to: Dr. Bikash Bose, C-79 Omega Drive, Newark, Delaware 19713. Received December 18, 1996; accepted March 24, 1997. © 1998 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010

nterior cervical osteosynthesis screw and plate systems have been used to enhance stability and improve fusion rates in cervical spine surgery. Caspar has developed a standardized commercially available screw and plate fixation system. The anterior cervical approach for cervical spine disease was initially popularized by Cloward and subsequently modified by Smith and Robinson. However, in an unstable spine additional stabilization devices may be necessary. The Caspar plating system has been used to treat a variety of cervical spine diseases including disc disease, instability secondary to trauma, failed fusion, pseudoarthrosis after disc surgery, and tumors involving the cervical spine. Many investigators have recorded experience using the Caspar trapezial osteosynthetic plate system as reviewed [5,6,10,12–14,19,21,26, 28,29].

A

Methods Ninety-seven patients who underwent anterior cervical spine surgery with Caspar plating between July 1990 and December 1995 were included in this study. The average follow-up for these patients was 9 months. The ages of the patients ranged from 17 to 80 with a mean of 50.32 (6 SD 12.83). Forty-four of the patients were male and fifty-three were female. The average hospital stay for the patients was 0090-3019/98/$19.00 PII S0090-3019(97)00306-6

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approximately 3 days for patients with degenerative spinal conditions and longer for patients with spinal cord injuries. Ninety-seven patients underwent anterior cervical fusions after discectomy and/or corpectomy. Fibular allograft was used in 13 cases and iliac crest graft was used in the remaining patients. The indications for using the Caspar plating system were: a) post-traumatic instability, b) three or more levels of decompression and fusion for cervical spondylosis and/or disc disease, c) failed fusions, d) one or two level fusions associated with abnormal kyphosis and/or subluxation, and e) instability caused by metastatic disease. All patients in this series were operated on in a Stryker frame. Gardner-Wells tongs were applied before surgery and 15 to 20 pound weights were used for cervical traction. A big roll was placed across the shoulders to extend the neck. A generous transverse incision was employed for exposure. Extensive subplatysmal dissection was done. Then, dissecting in the plane between the sternocleidomastoid and the esophagus, the anterior cervical spine was approached as has been described previously. The Caspar retraction system was then positioned for adequate exposure. After discectomy, decompression, and fusion, a fluoroscopic C-arm unit was positioned in a true lateral plane and the appropriate Caspar plate was selected. The plates were contoured with a plate bender. Then under fluoroscopic guidance the plating was done. After the positioning of all the screws the traction weight was removed and the screws were then hand tightened. The incision was then closed in a standard fashion and a Jackson-Pratt drain No. 7 flat was used postoperatively for 48 h. An intraoperative lateral cervical spine X-ray was taken in the operating room before transferring the patient to the post anesthesia care unit. A Philadelphia collar was placed around the neck and the Gardner-Wells tongs were removed. The patients were immobilized in an external orthosis Philadelphia collar for an average of 8 weeks post surgery, (9.59 weeks (6 SD 3.16) for patients with autografts and 12.83 weeks (6 SD 4.02) for patients with allografts). Perioperative antibiotics (Kefzol, Cefazolinsodium, Lilly) were administered for 48 h. A Foley catheter was inserted in all of the patients before surgery and was removed within 24 h after surgery. Difficulty was encountered in visualizing the lower end of the cervical spine, especially the posterior cortex of the C-7 vertebral body, in shortnecked and wide-shouldered individuals. To circumvent this difficulty, either the arms were pulled down using wrist restraints that were applied dur-

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ing positioning of the patient, or the C-arm tube was angled slightly to give a semi-Swimmers view during surgery.

Results Ninety-seven patients underwent anterior cervical fusions following discectomies and/or corpectomies. Fibular allograft was used in 13 cases and iliac crest graft was used in the remaining 84 patients. Six patients had four levels fused; 52 had three levels fused; 27 had two levels fused; and 12 had only one level fused. Nineteen patients developed instrumentation failure. Seven patients developed fracture of one screw each, one superior (Figure 1A, B) and six inferior screws (Figure 2A, B). Ten patients developed screw backout (inferior screw). In one patient the superior screws were 2 mm posterior to the posterior cortex but did not cause any neurologic deficits (Figure 3A, B). Seven of these patients underwent revision surgery. Two developed temporary deltoid weakness and three developed transient recurrent laryngeal nerve palsy. One patient developed acute airway obstruction, but this patient had a pre-existing epiglottic anomaly and sleep apnea disorder (Fig. 4A, B). One patient with mild cerebral palsy developed severe swallowing difficulty, which resolved over 4 months. Another patient developed cricothyroid muscle weakness and was unable to attain high tones without any abnormalities of the vocal cord. Forty-one of the patients were smokers (42.2%). Solid fusion was attained in all but two patients (97.9%). Allografts had been used in the two patients who did not fuse. There was no correlation between corpectomies, discectomies, and instrumentation failure. There were no infections in this series. No complications related to the instrumentation were encountered in the last 34 cases. Allograft was used in five of the seven patients who had screws back out. The significant factors associated with the failure of Caspar plates in this series were a) allograft and b) multilevel plates. Lower screws backed out in all failures. Use of bigger “rescue” screws in the inferior end of long constructs eliminated this problem.

Discussion Orozcor and Llovet first approved the use of anterior cervical plate stabilization for fixation of the traumatically unstable spine in 1970 [18]. Subsequently Caspar described his experiences using the trapezial osteosynthetic plate developed by him for anterior stabilization of the cervical spine [5,6]. An-

Caspar Plating: Analysis of Results

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Cervical spine X-rays of three-level anterior cervical fusion with Caspar plating 1 month postoperatively (A) and 6 months postoperatively show fracture of superior screw (B). This was one of the earliest cases; subsequently the intermediate vertebrae were instrumented in all cases.

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terior cervical fusion for disc disease as well as trauma was first popularized by Cloward, Smith, and Robinson [7,8,24]. However, in the presence of ligamentous instability this method does not provide adequate stabilization and different forms of external arthrosis have been used as an adjunct after surgery for the highly unstable spine. The Caspar trapezoidal osteosynthetic plate system provides immediate additional stability of the spine and has been shown to improve the fusion rates after surgery. Theoretically, at least, it has a biomechanical advantage because of bicortical screw fixation. Caspar reported the use of his system in

stabilizing the cervical spine following trauma and obtained 100% fusion in 60 cases [5]. Tippets and Apfelbaum recorded their experience using the same system in cases of disc disease (degenerative or inflammatory), failed fusion with disc surgery, cervical spine trauma, and tumors involving the cervical vertebral bodies [26]. They had extremely favorable results with fusion in all cases, no evidence of graft extrusion on screw loosening, and no worsening of neurologic status after surgery. Bremer and Nguyen described their experience with the use of a modified method of internal metal fixation combined with anterior interbody fusion in

This female patient underwent three-level ACT using allograft and went on to fuse (A). However, 2 years postoperatively she developed severe neck pain, signs of cord compression, and was found to have fractured an inferior screw (B).

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Summary of Patient Information

I. Patient Categories (a) Degenerative (b) Trauma (c) Tumor II. Type of Surgery Corpectomies Discectomies III. Smokers Non-smokers IV. Instrumentation Failure (a) Autograft (b) Allograft V. Revision Surgery (a) Autograft (b) Allograft

No. 85 8 5 15 83 41 56 19 13/84 6/13 7/97 2/84 5/13

Analysis of Complications

NO. I. Instrumentation Failure Screw Fracture Inferior Screw Fracture Superior Screw Backout (Inferior) Screws Too Deep (No Neurological Deficit) II. Soft Tissue Injury Deltoid Weakness Recurrent Laryngeal Nerve Weakness Acute Airway Obstruction Cricothyroid Muscle Injury III. Pseudoarthrosis

six patients with unstable lower cervical spines [3]. All patients were maintained in a hard cervical collar until satisfactory fusion had occurred, which was usually at about 12 weeks. They reported that this method of internal fixation allowed very early mobilization and markedly reduced hospital stay, and was not associated with any significant morbidity. Smith and Bolesta first reported esophageal perforation after anterior cervical plate fixation using the EO small fragment Y plate and 4.0 mm cancellous screws [25]. Goffin reported the successful use of Caspar osteosynthetic plate with a C-shaped iliac crest graft for subdural cervical vertebral body replacement in cases of teardrop fractures or burst compression fractures [12]. Goffin et al reviewed their experience using the Caspar plate in anterior stabilization of the spine

One month postoperative X-rays (A) show encroachment of the spinal canal even though the intraoperative fluoroscopy seemed satisfactory and there was no neurologic deficit. Postoperative X-rays after revision surgery show adequate position of screws. A regular lateral c-spine X-ray is now routinely done in the operating room before closure.

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19 (all multilevel fusions) 6 1 10 2 2 (temporary) 3 (temporary) 1 (pre-existing sleep apnea disorder from epiglottic anomaly) 1 (partial recovery) 2 (allograft)

and reported 93% excellent realignment of the cervical spine [13]. They reported an overall postoperative mortality of about 10%, and a mortality of 24% for patients with complete transverse cord lesions. Their patients had a variety of abnormalities including bilateral facet dislocation, unilateral facet dislocation, anterior subluxation, anterior compression fracture, hangman’s fracture, and hyperextension injury at the lower cervical level. Pasztor et al treated 15 patients with cervical spine dislocations and kyphotic spondylosis caused by traumatic fracture and vertebral body tumor in one stage using the anterior approach and metal plate stabilization [20]. The majority of the

Caspar Plating: Analysis of Results

MRI shows severe cervical spondylosis (A). Sixmonth postoperative X-ray shows solid fusion after a four-level procedure (B).

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operations were late decompressions. Patients with root or partial cord lesions made the most significant recovery. Experience from this series supports the concept that the unstable spine caused by posterior pathology can be stabilized adequately using Caspar plating and postoperative bracing. Oliveira used anterior plate fixation for traumatic lesions of the lower cervical spine in 40 patients without major complications [17]. Stability and alignment of the spine was achieved in all cases. Lesoin et al described a modification of the Caspar plate that they proclaimed had the advantage of offering the surgeon choice for optimal positioning of the screws [15]. This method also used expanding bolts. Gassman and Seligson reported their experience using the anterior plate system in 13 anterior cervical spine fusions done for traumatic,

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degenerative, and infective lesions [11]. Satisfactory alignment of the cervical spine was obtained in 11 patients, and 1 patient required plate and screw removal approximately 2 months after the initial surgery with the screw loosening causing dysphagia. All the patients achieved solid fusion. Controversy exists about whether traumatic posterior spinal injury should be treated by anterior surgery and whether internal fixation by metal plate is necessary or advisable. Aebi et al reported experience using the anterior plating system (Orozco plate) [21,18]. In 86 patients who sustained cervical spine injury the average follow-up was 40 months. Twenty-two patients had predominantly anterior lesions, whereas 64 patients had predominantly posterior lesions. Both groups were treated by anterior fusion with bone grafting and plating using Orozco plates. They reported no nonunions; one patient developed a loose screw without consequences to the patient. Another patient developed a transient Horner’s Syndrome which fully recovered. Their findings strongly supported the use of anterior plate fixation and fusion for spine lesions, even those involving predominantly the posterior elements. Coe et al evaluated various posterior and anterior constructs biomechanically in human cadaveric spines [9]. They reported significant biomechanical disadvantages using the Caspar plate compared with all posterior fixation methods when treating distractive flexion injuries of the cervical spine. However, no bone graft was used in the study specimens using the Caspar stabilization technique, although it is an integral part of the procedure. Garvey et al reported their experience with 14 patients who sustained acute cervical spine fractures and/or dislocation with associated posterior ligamentous destruction; all underwent anterior decompression, structural bone grafting and anterior Caspar plate stabilization [14]. Their experience was contrary to published reports stating that the anterior Caspar plating was biomechanically inferior to posterior stabilization techniques. They showed that stabilization with the Caspar plate was a treatment option for patients with cervical spine fractures and dislocations having associated disruption of the posterior ligamentous elements when a simultaneous anterior decompression is necessary. Thus, when an anterior approach is required for decompression anterior Caspar plating may be used as an adjunct to bone grafting, thus eliminating the need for additional posterior stabilization. Caspar and Goffin have emphasized the importance of penetration to the posterior vertebral body cortex for enhancing stability [5,6,12,13]. Maiman et

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al studied the pullout strength of Caspar cervical screws and reported that posterior cortical penetration did not improve the pullout the strength of Caspar screws in an isolated vertebral body model [16]. Tippets and Apfelbaum suggested that bicortical fixation provides a construct that resists virtually all potentially pathologic forces [26]. Traynelis performed a biomechanical comparison with anterior Caspar plates and three-level posterior fixation techniques in a human cadaveric model [27]. This study involved two motion segments and provided biomechanical evidence that supported the observed clinical effectiveness of bicortical anterior plate stabilization of traumatic cervical spine injuries. Progressive kyphosis after cervical laminectomy performed as a posterior decompression procedure is still a common complication and can occur in individuals undergoing an extensive cervical laminectomy. The incidence is higher in the pediatric population. Herman and Sonntag reported their experience with anterior decompression and fusion using cervical plating in patients presenting with progressive kyphosis and instability after laminectomy for either cervical spondylosis or spinal tumors [14]. Their data suggested that immediate fixation with anterior plating facilitated solid fusion, maintained spinal curvature, and promoted neurologic improvement. Caspar et al reported a 5% incidence of screw pullout that was related to poor purchase in the posterior cortical bone of the vertebral body [5]. Herman and Sonntag believed that when the Caspar system was used, it was mandatory to engage the posterior cortex with the screw [14]. Papadopoulos, Sonntag, and Kalphas reviewed their combined experience using Caspar plate stabilization in 160 patients [19]. All patients progressed to stable fusion, and the overall complication rate requiring reoperation related to the instrumentation was 4.4%. Complications from the procedure requiring reoperations were not insignificant, but diminished with adequate experience with the technique [19]. This has been the experience in our series. Computed tomography scan and magnetic resonance imaging aid in the early diagnosis and treatment of osseous lesions of the cervical spine. These advances, combined with more aggressive surgical resection and spinal stabilization using spinal instrumentation, have decreased the morbidity and mortality associated with these lesions [4]. Randle et al reported experience with the Caspar technique and instrumentation for anterior stabilization in 54 patients with acute cervical spine injuries operated

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on within 24 h [21]. All patients showed a solid fusion within 6 months of surgery. The surgical complications included two cases of screw loosening (3.7%), one infection in the neck (1.85%), and one in the hip bone. In two cases the plates had to be removed; however, the fusion was found to be solid. Based on their experience they suggested that although anterior cervical fusion and Caspar plating remained appropriate for patients with documented anterior spinal pathology, it should not be substituted for traditional posterior stabilization procedures. A recent report emphasized the utility of Caspar instrumentation in patients with facet pathology [13]. Wolf et al used the anterior approach in Caspar plating procedure after closed reduction of facet dislocations when there was either a complex fracture of adjacent facets, a retropulsed fragment compromising the spinal canal, or compression by a vertebral disc [29]. Caspar plate fixation has been used in the treatment of complex hangman’s fractures that have failed conservative management consisting of closed reduction and immobilization in a halo [28]. Tuite reported initial experience using C2-3 interbody bone fusion and Caspar plate fixation in treatment of these lesions and obtained 100% fusion rate with no complications related to plating or nonunion [28]. In conclusion the Caspar plating system is versatile and may be used in a variety of cervical spine disorders as an adjunct to fusion to improve the success rate. The complication rate decreases significantly with experience. Use of rescue screws at the inferior end of long constructs reduces instrumentation-related failures. I would like to acknowledge the assistance of Dorothy Bose, R.N., B.S.N.; Marykay Ennis; and Michelle Bellon, who helped with the preparation of the manuscript.

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COMMENTARY

This is a series of 97 patients who underwent anterior cervical decompression and fusion over several levels using the Caspar plate system. The author points out the various indications for the operative procedure and indications for the use of the Caspar anterior cervical plate. Instrument failure was significant, especially in the early experience, and the author has been honest in documenting the various problems encountered in this series. Arnold H. Menezes, M.D. Division of Neurosurgery University of Iowa Hospital Iowa City, Iowa