Anterior Decompression and Stabilization with the Kaneda Device for Thoracolumbar Burst Fractures Associated with Neurological Deficits* 1

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1 Copyright 1997 by The Journal of Bone and Joint Surgery, Incorporated Anterior Decompression and Stabilization with the Kaneda Device for Thoracolumbar Burst Fractures Associated with Neurological Deficits* 1 BY KIYOSHI KANEDA, M.D.t, HIROSHI TANEICHI, M.D4, KUN1YOSH1 ABUM1, M.D4, TOMOYUK1 HASHIMOTO, M.D4. SHIGENOBU SATOH, M.D4, AND MASANORI FUJIYA, M.D., SAPPORO, JAPAN Investigation performed at the Department of Orthopaedic Surgery, Hokkaido University School of Medicine, and Hokkaido Orthopaedic Memorial Hospital, Sapporo ABSTRACT: One hundred and fifty consecutive patients who had a burst fracture of the thoracolumbar spine and associated neurological deficits were managed with a single-stage anterior spinal decompression, strut-grafting, and Kaneda spinal instrumentation. At a mean of eight years (range, five years to twelve years and eleven months) after the operation, radiographs showed successful fusion of the injured spinal segment in 14 patients (9 per cent). Ten patients had a pseudarthrosis, and all were managed successfully with posterior spinal instrumentation and a posterolateral arthrodesis. The percentage of the canal that was obstructed, as measured on computed tomography, improved from a preoperative mean of 47 per cent (range, 4 to 9 per cent) to a postoperative mean of per cent (range, to 8 per cent). Despite breakage of the Kaneda device in nine patients, removal of the implant was not necessary in any patient. None of the patients had iatrogenic neurological deficits. After the anterior decompression, the neurological function of 14 (95 per cent) of the 15 patients improved by at least one grade, as measured with a modification of the grading scale of Frankel et al. Fifty-six (7 per cent) of the seventy-eight patients who had preoperative paralysis or dysfunction of the bladder recovered completely. One hundred and twenty-five (96 per cent) of the 1 patients who were employed before the injury returned to work after the operation, and 11 (86 per cent) of them returned to their previous job without restrictions. We concluded that anterior decompression, strut- *No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study. tread in part at the Annual Meetings of the Scoliosis Research Society, Amsterdam, The Netherlands, September, 1989, and Portland, Oregon, September, 1994, and at the Annual Meetings of The American Academy of Orthopaedic Surgeons, Anaheim, California, March 8,1991, and Orlando, Florida, February,1995. ^Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 6, Japan. address for Dr. Kaneda: kkaneda@ga.so-net.or.jp. Hokkaido Orthopaedic Memorial Hospital, Hiragishi 7-1-5, Toyohira-ku, Sapporo 6, Japan. grafting, and fixation with the Kaneda device in patients who had a burst fracture of the thoracolumbar spine and associated neurological deficits yielded good radiographic and functional results. Burst fractures are a common major injury of the thoracolumbar spine and have been reported to be associated with neurological deficits in two of thirteen patients in one series 1, twelve ( per cent) of forty in another 14, and fourteen (56 per cent) of twenty-five in another 5. The indications for operative decompression and the selection of an operative procedure for stabilization of a thoracolumbar burst fracture associated with neurological deficits are controversial. Laminectomy has been shown not only to be ineffective for restoration of neurological function but also to allow further progression of deformity and neurological injury 1. Accepted methods of operative decompression and stabilization of this type of spinal injury include posterior reduction with distraction instrumentation and arthrodesis without decompression (ligamentotaxis) 514 ", posterolateral (transpedicular or costotransversectomy) decompression and arthrodesis with posterior instrumentation 79, posterior or posterolateral arthrodesis with instrumentation followed by anterior decompression and arthrodesis or anterior decompression and arthrodesis followed by posterior instrumentation and arthrodesis 66, and anterior decompression and arthrodesis with anterior instrumentation 1 5. Many investigators have reported favorable results from anterior decompression by direct removal of the fragments of the vertebral body from the spinal canal 64. However, several questions remain with regard to whether the retropulsed osseous fragments in the spinal canal should be removed, whether instrumentation should be used for spinal realignment and arthrodesis after decompression, and whether the spinal instrumentation should be placed anteriorly or posteriorly. Since reporting on our early series, we have managed all patients who had a thoracolumbar burst fracture associated with neurological deficits with a one-stage VOL. 79-A, NO. 1, JANUARY

2 7 KIYOSHI KANEDA ET AL. TABLE I RELATIONSHIP BETWEEN THE FRACTURED VERTEBRAL LEVEL AND THE TYPE OF NEUROLOGICAL LESION* Tvoe of Level of Fracture Neurological Lesion T1 LI L L L4 T1 + LI LI + L L + L L + L5 T6 + L + L5 Spinal cord (cephalad to the epiconus spastic) Spinal cord (at the epiconus flaccid) Pure conus medullaris syndrome Conus medullaris and cauda equina Cauda equina or nerve root, or both Total *The values are given as the number of patients. tdecompression at the fifth lumbar level was performed by means of a posterior procedure It It 1 procedure of anterior decompression and arthrodesis with use of the Kaneda device for fixation. The purpose of the present study was to analyze the long-term results for 15 patients who had been managed with this protocol. Materials and Methods From April 1981 to March 1989, 16 consecutive patients who had neurological deficits because of a burst fracture of the thoracolumbar spine were managed operatively at Hokkaido University Hospital and Hokkaido Orthopaedic Memorial Hospital in Sapporo, Japan. The indication for the operation was a persistent neurological deficit from encroachment on the spinal canal by the retropulsed osseous fragments. In most instances, the operation was performed when the neurological status of the patient had plateaued with only limited recovery. Thirteen patients were excluded from this investigation. Two patients died. One, a seventeen-year-old boy who had had uncontrolled diabetes mellitus and a severe urinary-tract infection preoperatively, died of pneumonia fourteen days after the operation. The other patient, a fifty-seven-year-old man, died because of a rupture of an esophageal varix two years and seven months postoperatively. The other eleven patients were lost to follow-up. All of these patients had been followed for two to three years postoperatively, had returned to their previous jobs, and were noted to have a fusion of the injured spinal segments at the most recent follow-up examination. Some degree of neurological recovery had been documented in all thirteen patients, and none of the thirteen had a complication during the follow-up period. We reviewed the results for 15 patients who had been followed for a minimum of five years. There were 19 male and forty-one female patients. They had a mean age of forty-one years (range, thirteen to seventy-two years). The male patients had an average height of 168 centimeters (range, 15 to 178 centimeters), and the female patients had an average height of 155 centimeters (range, 145 to 164 centimeters). The body weight of the patients ranged from fifty-three to eighty-six kilograms; the male patients weighed an average of sixty-seven kilograms and the female patients, an average of fifty-six kilograms. Most of the patients were transferred to our institutions from other hospitals and, therefore, the injuries were not acute. The interval from the injury to the operation was less than forty-eight hours for seven patients, two to less than fourteen days for thirty-eight patients, two weeks to less than one month for forty-five patients, one to less than six months for forty-one patients, six to twelve months for eight patients, and more than one year for eleven patients. The mechanism of injury included a fall from a height (ninety-four patients), a motor-vehicle accident (thirty-seven patients), a fall from a height during a suicide attempt (nine patients), and a direct impact from a falling heavy object (ten patients). Associated trauma included facial or cranial injury (five patients), thoracic injury (nine patients), urogenital injury (three patients), pelvic fracture (four Level of Fractured Vertebra T6 T1 LI L L L4 L5 Total TABLE II OBSTRUCTION OF THE SPINAL CANAL* No. of Fractured Vertebrae Obstructiont (Per cent) Preoperative Postoperative 11 4 (6-54) 46 (-8) 58 (8-9) 6 (47-67) (4-48) 19(17-1) 47 (4-9) (-7) (-8) (-5) (-) (-) (-) (-8) *The ratio of the maximum area of the retropulsed osseous fragment to the area of the original spinal canal. tthe values are given as the mean, with the range in parentheses. THE JOURNAL OF BONE AND JOINT SURGERY

3 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 71 TABLE III GRADING SYSTEM OF FRANKEL ET AL., AS MODIFIED BY BRADFORD AND MCBRIDE'', FOR NEUROLOGICAL ASSESSMENT Grade A B C Dl D D E Motor Function* (Points) Function of Bladder and Bowel Paralysis Paralysis Paralysis or dysfunction Paralysis to normal Paralysis! Dysfunctionf Normal Normal *Motor function was determined by manual muscle-testing. tthe pure conus medullaris syndrome is included in Dl or D. patients), injury of the upper extremities (twelve patients), and injury of the lower extremities (twenty-nine patients). All patients had anteroposterior and lateral radiographs of the spine, preoperative myelography with myelographic tomography or myelographic computed tomography, and preoperative and postoperative computed tomography. Myelographic tomography and myelographic computed tomography were used to evaluate the relationship between the epiconus, conus medullaris, or cauda equina and the retropulsed osseous fragments. These radiographic examinations were performed either at the referring hospitals or at our hospitals. The 15 patients had 158 burst fractures; 14 patients had a fracture at a single level, six patients had two contiguous or non-contiguous vertebral fractures, and one patient had three non-contiguous fractures (Table I). According to the classification system of Denis 1, thirty-eight (4 per cent) of the fractures were type A (a fracture of both of the end plates); ninety-two (58 per cent), type B (a fracture of the superior end plate); ten (6 per cent), type C (a fracture of the inferior end plate); eleven (7 per cent), type D (a burst rotation fracture); and seven (4 per cent), type E (a burst lateral flexion fracture). One hundred and twenty-three (78 per cent) of the 158 burst fractures were associated with a fracture of the lamina at the same level. There was no evidence of nerve tissue interposed or trapped within the laminar fractures on the preoperative myelographic or plain computed tomography scans. The original area of the spinal canal was calculated by averaging the areas of the spinal canal cephalad and caudad to the injured vertebra. The percentage of obstruction of the spinal canal (the ratio of the maximum area of the retropulsed osseous fragment or fragments to the area of the original spinal canal) was estimated on the preoperative computed-tomography scan according to our previously reported method 1 (Table II). The nerve-root lesions in the five patients who had a burst fracture of the fourth lumbar vertebra were associated with a smaller percentage of obstruction of the spinal canal. These nerve-root lesions were attributed to retropulsed bone that had narrowed the lateral recesses and resulted in compression of the nerve roots. Fractures of the sixth thoracic and fifth lumbar vertebrae were not associated with neurological deficits. Burst fractures of the fourth or fifth lumbar vertebra associated with neurological deficits have not been treated with anterior decompression and instrumentation at our institutions since June The neurological deficits were divided into five groups according to the level of the nerve injury: the spinal cord cephalad to the epiconus (spastic) (three patients), the epiconus (flaccid) (thirty-two patients), the conus medullaris only (thirteen patients), both the conus medullaris and the cauda equina (thirty-three patients), and the cauda equina or an isolated nerve-root lesion (sixty-nine patients) (Table I). The pure conus medullaris syndrome was defined as a disturbance in the function of the anal and bladder sphincters with sensory loss in the perineal area only (no loss of motor function or sensation in the lower extremities). Neurological assessment was performed with use of the new grading scale of Frankel et al., as modified by Bradford and TABLE IV RELATIONSHIP BETWEEN THE TYPE OF NEUROLOGICAL LESION AND THE NEUROLOGICAL GRADE* Type of Neurological Lesion A Preoperative B Grade According C to the Modified Dl System D of Frankel et al. 6 D Total Spinal cord (cephalad to the epiconus spastic) Spinal cord (at the epiconus flaccid) Pure conus medullaris syndrome Conus medullaris and cauda equina Cauda equina or nerve root, or both Total *The values are given as the number of patients. VOL. 79-A, NO. 1, JANUARY 1997

4 7 KIYOSHI KANEDA ET AL. FIG. 1-A Figs. 1-A through 1-G: Drawings showing the operative procedure. Fig. 1-A: After excision of the intervertebral discs cephalad and caudad to the injured level, the fractured vertebral body is excised with use of a chisel, leaving the anterior longitudinal ligament intact. The displaced fragments of the vertebral body are removed from the anterior aspect of the posterior longitudinal ligament or thecal sac with use of long, sharp curets. McBride 6 (Table III). We also used the lower-extremity motor-index scale 17 for the evaluation of motor function, which is performed by manual, bilateral testing of five muscles (the iliopsoas, quadriceps femoris, tibialis anterior, extensor hallucis longus, and gastrocnemius). A normal score is 5 points. The neurological deficits occurred immediately after the injury in 16 patients, and in thirty-four of them the deficits improved by at least one grade between the time of the injury to the time of the operation. However, all 16 patients demonstrated some neurological deficits at the time of admission to our hospitals (Table IV). In fourteen patients, the onset of the neurological deficits was delayed from one to six months after the injury. The delayed onset of neurological loss from the unstable burst fractures was attributed to increased kyphosis or late segmental instability, which caused neurological compression by retropulsed osseous fragments in the spinal canal. The preoperative function of the bladder was urodynamically evaluated by means of cystometry with estimation of residual urine. The patients were also asked about the sensation of a full bladder, episodes of incontinence, and the need for self-catheterization. Thirtythree patients ( per cent) had paralysis of the bladder and forty-five ( per cent) had dysfunction of the bladder on admission to our hospitals. Seven patients had been managed with a posterior procedure before admission to our hospitals. Posterior instrumentation for reduction and decompression by ligamentotaxis had been performed in three patients; laminectomy and posterolateral arthrodesis with instrumentation, in two; and posterolateral decompression and arthrodesis with instrumentation, in two. All of these patients still demonstrated neurological deficits (grade C in one, Dl in two, D in three, and D in one, according to the modified system of Frankel et al. 6 ) at the time of the anterior decompression at our hospitals. The posterior instrumentation was removed before the anterior procedure was performed. Operative Procedure An extrapleural and retroperitoneal approach with removal of the left tenth or eleventh rib was used to expose the thoracolumbar junction (the eleventh and twelfth thoracic and first lumbar vertebrae). The twelfth rib was not removed from most patients because it is too small and weak for use as a strut graft. Three vertebrae (the fractured vertebra as well as one cepha- FIG. 1-B Anterior decompression must be performed until the base of the contralateral pedicle is well visualized. THE JOURNAL OF BONE AND JOINT SURGERY

5 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 7 TABLE V PREOPERATIVE AND POSTOPERATIVE EVALUATION OF NEUROLOGICAL FUNCTION, ACCORDING TO THE MODIFIED SYSTEM OF FRANKEL ET AL. 6 Preoperative Grade Grade at Most Recent Follow-up Examination* C Dl D D A B C Dl D D E t t It 5 (t, t) (it,$) 5t t t *The values are given as the number of patients. tpatients who had no recovery of function of the bladder and bowel. tpatients who had partial recovery of function of the bladder and bowel. lad and one caudad to it) were exposed. The second, third, and fourth lumbar vertebrae were exposed by the retroperitoneal approach with removal of the eleventh rib. The intervertebral discs cephalad and caudad to the injured level were almost completely excised, leaving the anterior longitudinal ligament intact (Fig. 1-A). The vertebral resection for anterior decompression of the spinal canal was done, leaving the anterior and contralateral cortices of the fractured vertebral body intact (Fig. 1-B). The displaced fragments of the vertebral body in the spinal canal were removed from the anterior aspect of the posterior longitudinal ligament with use of long sharp curets. The posterior longitudinal ligament was often found to be disrupted or attenuated as a result of the original injury, but it was not removed in order to avoid bleeding from the epidural venous plexus. The anterior decompression was not judged to be complete until the base of the contralateral pedicle was well visualized. After complete decompression, the vertebral plates of the Kaneda device were attached to the lateral aspect of the vertebral bodies cephalad and caudad to the vertebrectomy with the use of a punch and screw fixation (Fig. 1-C). In the fifty-four patients who had the operation before June 1984, the Mark-I model of the Kaneda device (without rod couplers) (Mizuho FIG. 1-D The relation of the direction of the screws and the vertebral plate should be triangular, and the screws must penetrate the contralateral cortex. V.C. = vena cava and Ao. = aorta. FIG. 1-C After complete decompression, the vertebral plates of the Kaneda device are gently attached to the lateral aspect of the vertebral bodies cephalad and caudad to the vertebrectomy. Then, two screws are inserted into each vertebral body. A finger is passed across the vertebral body in order to feel the tip of the penetrated screw and to make sure that it does not protrude more than three or four millimeters beyond the vertebral body. Ikakogyo, Tokyo, Japan) was used. The Mark-II model of the Kaneda device (with rod couplers) was used in the ninety-six patients who were managed since June The relationship of the direction of the screws and the vertebral plate was triangular, and the screws had to penetrate the contralateral cortex (Fig. 1-D). Kyphosis was corrected by use of a spreader device applied to the heads of the two anterior screws (Fig. 1-E). Correction of the kyphosis was judged by checking the arrangement of the end plates of the vertebrae cephalad and caudad to the vertebrectomy. In patients who had late presentation of kyphosis, the anterior longitudinal ligament was often scarred and needed to be sectioned at the level of the disc. After the kyphosis was corrected, the length of the VOL. 79-A, NO. 1, JANUARY 1997

6 74 KIYOSHI KANEDA ET AL. FIG. 1-E Kyphosis is corrected with use of a spreader device applied to the heads of the two anterior screws. The tricortical iliac-crest graft and two or three pieces of rib are placed as a strut into the vertebrectomy gap. gap was measured from vertebral end plate to vertebral end plate and a tricortical iliac-crest graft was obtained. The defect of the iliac crest was reconstructed with a ceramic substitute (bioactive apatite-wollastonite glassceramic; Nippon Electric Glass, Ootsu, Japan). The tricortical iliac-crest graft and two or three struts of rib were placed into the defect created by the distracted vertebral resection. In the first 19 patients, the bone grafts were placed with the tricortical portion adjacent to the instrumentation. In the forty-one patients who had the operation in 1987 or later, the tricortical portion of the iliac-crest graft was inserted opposite the Kaneda plate, near the contralateral pedicles (Fig. 1-F). Bone chips from the resected vertebral body were packed into the gap between the iliac-crest graft and the anterior vertebral wall (Fig. 1-F). FIG. 1-F The tricortical portion of the iliac-crest graft is inserted in the frontal plane beyond the contralateral pedicles. Bone chips from the resected vertebral body are packed into the gap between the iliaccrest graft and the anterior vertebral wall. FIG. 1-G After bone-grafting, threaded rods and two sets of the rod couplers are applied. THE JOURNAL OF BONE AND JOINT SURGERY

7 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 75 TABLE VI SCORES ACCORDING TO THE LOWER-EXTREMITY MOTOR INDEX 1 ' Involved neural element Spinal cord Cauda equina Time from injury to operation Within one month More than one month Onset of neurological deficit Immediately after injury Delayed onset No. of Patients* Scoref (Points) Preoperative Postoperative (-49) 45 (5-49) 41 (-48) 4 (-49) 4 (-47) 45 (5-49) 4 (-5)$ 49 (4-5)t 48 (-5) 48 (-5) 47 (-5)f 49 (4-5)1 "Thirteen patients who had pure conus medullaris syndrome were excluded. fthe values are given as the mean, with the range in parentheses. ^Significantly different (p <.1; Welch t test). Not significantly different. INot significantly different. After bone-grafting, threaded rods and two sets of rod couplers were applied (Fig. 1-G). When there was a potential for compression of the aorta by an implant located at the eleventh thoracic level (three patients), the implants were covered with a Teflon (polytetrafluoroethylene) sheet. The wound was then closed and drained in the standard fashion. A chest tube was not necessary for most of the patients who had been managed with the extrapleural and retroperitoneal approach. The pleura was checked for air leaks by pouring saline solution into the extrapleural retroperitoneal space just before wound closure. A chest tube was used in nine (1 per cent) of the ninety-three patients who had a burst fracture of the twelfth thoracic or first lumbar vertebra and in whom the pleura had been injured. No chest tube was used in the patients who had a burst fracture of the second, third, or fourth lumbar vertebra. No postoperative pneumothorax occurred in any of the patients who did not have a chest tube. Postoperative Care At four to seven days after the operation, the patients were encouraged to walk with a polypropylene thoracolumbosacral orthosis, which was worn for twenty to twenty-four weeks. Eleven patients who had a delayed union or a pseudarthrosis wore the brace for more than six months. The patients were taught to continue active isometric exercises of the trunk muscles while wearing the thoracolumbosacral orthosis. After removal of the brace, the patients who were not manual laborers were allowed to perform the normal activities of daily living without any special restrictions. The manual laborers returned to their jobs six to eight months postoperatively. Follow-up The mean duration of follow-up was eight years (range, five years to twelve years and eleven months). The latest clinical and radiographic evaluations were conducted by two of us (H. T. and T. H.) who had not participated in the original operation. Statistical Analysis Statistical analyses were performed with use of the Welch t test or the Student t test. A p value of less than.5 was considered to be significant. Neurological Recovery Results None of the patients had neurological deterioration after the anterior decompression and stabilization. The patients stayed at our hospitals and at our affiliated rehabilitation hospitals for an average of twenty-four days (range, eleven to fifty-six days) after the operation. TABLE VII RECOVERY OF FUNCTION OF THE BLADDER AND BOWEL AT THE LATEST FOLLOW-UP EXAMINATION* Level of Recovery Complete! (n = 56) Incompleted (n = 9) None (n = 1) Total (n = 78) Cephalad to Epiconus Epiconus Type of Neurological Lesion Pure Conus Medullaris Syndrome *The values are given as the number of patients. The function of the bladder was normal. t-the patient had occasional incontinence but no need for self-catheterization. The patient needed catheterization Conus Medullaris and Cauda Equina Cauda Equina 9 1 VOL. 79-A, NO. 1, JANUARY 1997

8 76 KIYOSHI KANEDA ET AL. Figs. -A through -F: A forty-eight-year-old man sustained a burst fracture of the first lumbar vertebra with compression of the conus medullaris and the cauda equina. He had paralysis of the bladder and bowel, and neurological function was given a grade of C, according to a modification of the system of Frankel et al/\ Fig. -A: Preoperative myelogram. Fig. -B: Preoperative myelographic tomogram. The patients who had residual motor dysfunction that was severe (grade A in two patients and grade C in three patients postoperatively) needed a longer period of hospitalization for rehabilitation. The neurological function of 14 (95 per cent) of the 15 patients had improved at least one grade (Table V). Eight patients (5 per cent) had not recovered any neurological function at the time of the latest follow-up evaluation. Preoperatively and postoperatively, the neurological function of two of these patients, who had a burst fracture of the twelfth thoracic vertebra, was grade A; that of one patient, who had fracture of the first lumbar vertebra, was grade C; and that of five patients, who had a fracture of the first lumbar vertebra, was grade Dl (Table V). Two of these eight patients had sustained the spinal cord lesion cephalad to the epiconus; one, in the epiconus; and five, in the conus medullaris. Preoperatively, all eight patients had had complete loss of function of the bladder and the bowel with anesthesia of the perineal area. All seven patients who had been managed with a posterior procedure before the anterior procedure was performed showed some neurological recovery at the time of the follow-up evaluation. One patient had improvement from grade C to grade D; one, from grade Dl to D; one, from grade Dl to E; three, from FIG. -C Preoperative computed-tomography scan. THE JOURNAL OF BONE AND JOINT SURGERY

9 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 77 FIG. -D FIG. -E Radiographs made seven years and ten months after anterior decompression and arthrodesis with the Mark-II Kaneda device, which was performed in Although the patient had complete recovery of motor function, mild dysfunction of the bladder and bowel persisted (grade D, according to the modified system of Frankel et al. 6 ), despite complete decompression. grade D to E; and one, from grade D to E. The difference between the preoperative and postoperative scores on the motor-index scale was larger for the group that had a lesion of the spinal cord than for the group that had a lesion of the cauda equina (p <.1), but the final score was higher for the group that had a lesion of the cauda equina (Table VI). With the numbers available, we could not detect a significant association between the interval from the injury to the operation and the amount of postoperative neurological recovery. Thirteen patients who had no recovery of bladder function had had no sensation to pinprick in the perineal area preoperatively (Table VII). The patients who had had decreased sensation to pain in the perineal area preoperatively had incomplete or complete recovery of bladder function. Functional Results At the most recent follow-up examination, 11 patients (67 per cent) had returned to their previous occupation, thirteen (9 per cent) had changed to less strenuous work, and thirty-six (4 per cent) were unemployed. The unemployed patients included eleven (7 per FIG. -F Computed tomography scan made seven months after the operation. VOL. 79-A, NO. 1, JANUARY 1997

10 78 KIYOSHI KANEDA ET AL. TABLE CLINICAL RESULTS OF SHORT- Authors No. of Patients (No. with Neurol. Deficit) Duration of Follow-up* (Mos.) Level of Injury Type of Implant No. of Segments in Arthrodesis* Interval from Injury to Op. (Days) Posterior instrumentation (pedicular screw system) Esses et al. M Ebelkeetal. 1 Sasso et al.- 1 Carl et al. 7 Stephens et al. McNamara et al. 9 Benson et al. 5 McLain et al. 8 Viale et al. () 1 () 7(5) 8(9) 16() 1(6) 5 (1) 14 (?) 7 (7).1 (1-4) 17.(4-).(5-1).7 (1-9) 18.9(11-5).5 (8-4). (1-8) 15. (4-8) 18.7 T9-L T1-L4 L-L5 T1-L5 L1-L4 L1-L4 T1-L5 T1-L4 L1-L4 AO intern, fix. Steffee VSP Dyn. compres. plate Cotrel-Dubousset Cotrel-Dubousset Steffee VSP AO intern, fix. Cotrel-Dubousset Post. seg. device and Steffee VSP. (-). (-). (-6). (-4).7 (-4). (-4). (-).7 (-4) Anterior instrumentation Dunn 1 Kostuik 4 48 (4) 6 (?) T4-L5 Dunn Kostuik- Harrington -1 - Haas et al. 1 " Been 4 Present study 18 (?) 9 (1) 15(15) 7.(1-61) 1. (6-155) T4-L5 T6-L4 Dyn. compres. device and specially contoured spinal plale Slot-Zielke Kaneda 1.9(1-4).. (1-) - -7 yrs. *The values are given as the mean, with the range in parentheses. fpatients who had a neurological improvement of one grade 6 or more. Those who had a preoperative grade of A were excluded. tthe value is the mean improvement. The values represent the findings for the fractures of the twelfth thoracic and first lumbar vertebrae followed by those for the second, third, and fourth lumbar vertebrae. cent) who had reached retirement age after returning to their previous occupation, seven (5 per cent) who had retired before the operation, five ( per cent) who had paraplegia or paraparesis (incontinence), ten (7 per cent) who were managed for schizophrenia before and after the operation, and three ( per cent) who had alcoholism. Twenty patients (1 per cent) had not been working preoperatively. Therefore, 15 (96 per cent) of the 1 patients who had been employed before the injury returned to work after the operation; 11 (86 per cent) of those 1 patients returned to their previous jobs at full capacity. Patients who had performed light labor returned to work with the aid of a brace a mean of three months (range, one to five months) after the operation. Patients who had performed heavy labor returned to work with or without the aid of a brace a mean of seven months (range, six to nine months) after the operation. Pain in the back was assessed at the most recent follow-up examination with use of the pain scale of Denis". One hundred and fifteen patients (77 per cent) were given a rating of PI (no pain); twenty-one (14 per cent), a rating of P (occasional slight pain with no need for medication); ten (7 per cent), a rating of P (moderate pain with a need for occasional medication but no interruption of work or major change in activities of daily living); four ( per cent), a rating of P4 (moderateto-severe pain with a need for frequent medication and occasional absence from work or a major change in activities of daily living); and none were given a rating of P5 (constant or severe incapacitating pain and a chronic need for medication). The four patients who had a rating of P4 were receiving workers' compensation and demonstrated a complete neurological recovery. Radiographic Results The percentage of the spinal canal that was obstructed was evaluated before and after the operation (Table II). The fusion at the site of the three-level arthrodesis was evaluated on lateral flexion-extension radiographs and tomograms. A pseudarthrosis developed in six (11 per cent) of the fifty-four patients who had fixation with the Kaneda Mark-I device (without rod couplers); two of these patients had had a fracture of the second lumbar vertebra, two had had a fracture of the third lumbar THE JOURNAL OF BONE AND JOINT SURGERY

11 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 79 VIII SEGMENT ARTHRODESIS Neurol. Improve.t (Per cent) Obstruction of Canal (Per cent) Preop. Postop. Preop. Kyphosis (Degrees) Latest Follow- Postop. up Loss of Correct. Failure o f Implant. "" ' (Per cent) f. ' Non- Union (Per cent) Pain Relief (Per cent) Return to Work (Per cent) * grades^ , 6S, vertebra, and two had had a fracture of the fourth lumbar vertebra. A pseudarthrosis developed in four (4 per cent) of the ninety-six patients who had fixation with the Kaneda Mark-II device (with rod couplers); one of these patients had had a fracture of the first lumbar vertebra, two had had a fracture of the fourth lumbar vertebra, and one had had a two-level fracture at the second and third lumbar vertebrae. Over-all, fusion was achieved in 14 (9 per cent) of the patients. A pseudarthrosis developed in four of five patients who had had a burst fracture of the fourth lumbar vertebra. The mean height, body weight, and duration of hospitalization after the operation of the patients who had a pseudarthrosis were 165 centimeters, sixty-eight kilograms, and twenty-two days, respectively. These values were not significantly different from those for the patients who did not have a pseudarthrosis (p =.7, Student t test). All ten patients who had a pseudarthrosis had a successful repair with a posterolateral arthrodesis and posterior instrumentation, and all had a solid fusion at the most recent follow-up examination. Kyphosis was measured by the angle between the superior end plate of the vertebral body cephalad to the injury and the inferior end plate of the vertebral body caudad to the injury. This measurement was not performed for eighteen patients who had a burst fracture of the third or fourth lumbar vertebra because of the lack of a preoperative kyphotic deformity. The average kyphosis for the remaining 1 patients was 19 degrees preoperatively, 7 degrees at the time of discharge from the hospital, and 8 degrees at the most recent follow-up examination. Complications Seven of the ten patients who had a pseudarthrosis reported back pain and three did not; none of them showed neurological deterioration. Complications other than pseudarthrosis included failure of the device in nine patients who had a pseudarthrosis (breakage of a screw or screws in eight patients and breakage of the screws and the rod in one) intraoperative laceration of the inferior vena cava in one patient who had an old burst fracture of the second lumbar vertebra with severe kyphosis, a deep wound infection in one, a superficial wound infection in three, postoperative urinary-tract infection in three, postoperative atelectasis in ten, transient dysesthesia in the distribution of the genitofemoral nerve in five, and sympathectomy effect on the ipsilateral lower extremity in fifteen patients who had had exposure of the fourth or fifth lumbar vertebra, or both. All four postoperative infections were treated successfully with intravenous administration of antibiotics VOL. 79-A, NO. 1, JANUARY 1997

12 8 KIYOSHl KANEDA ET AL. FIG. -A Figs. -A through -D: A twenty-three-year-old man sustained a burst fracture of the fourth lumbar vertebra associated with injury of the cauda equina. Fig. -A: Preoperative tomogram. direct 646 or indirect" 415. Indirect decompression is accomplished with use of posterior instrumentation, with reliance on distraction, correction of any kyphosis, and ligamentotaxis to clear the canal of the displaced anterior bone and soft tissues. Ligamentotaxis is not always successful, and it has been reported that, at best, this method produces incomplete decompression of the spinal canal 8. With use of ligamentotaxis, Bradford and McBride found that the mean percentage of stenosis of the spinal canal, as determined with computed tomography scanning, was 6 per cent (range, to 5 per cent) postoperatively 6. If ligamentotaxis is to be successful, the technique should be performed within forty-eight to ninety-six hours after the injury 8. Crutcher et al.' reported that type-b fractures, according to the classification system of Denis 1, were often resistant to indirect reduction by ligamentotaxis, resulting in an incomplete decompression of the spinal canal. Many investigators have found that better results can be obtained with direct removal of the retropulsed fragments and soft-tissue debris from the spinal canal 614. One of the two methods of direct decompression is a transpedicular decompression through pedicular resection. It is difficult to decompress the far side of the canal with unilateral posterior transpedicular decompression, and there is a risk of iatrogenic neurological injury or incomplete decompression 8. Bilateral transpedicular decompression provides increased exposure of the canal, but it also increases vertebral instability. A few of the reported series in which transpedicular decompression and cancellous bone-grafting to the fractured body by means of the transpedicular approach were used have shown good results with slight loss of correction of the kyphosis, low rates of implant failure, and no increase in neurological complications 1. However, it is difficult to conceive how a cancellous (cephalosporin) for two to four weeks. The sympathectomy effects, which subsided spontaneously without any treatment within six to twelve months postoperatively, were hotness (twelve patients) and dryness (three patients) of the lower extremity, including the foot, on the side of the operation. None of the patients had an iatrogenic neurological injury, retrograde ejaculations, late vascular injury, or loosening of the hardware other than the nine patients who had pseudarthrosis and failure of the device. None of the implants needed to be removed. Discussion The indication for decompression of the spinal canal in patients who have a thoracolumbar burst fracture is a neurological deficit with radiographic evidence of obstruction of the spinal canal (Figs. -A through -F). The compressive tissues after a thoracolumbar burst fracture are invariably located in the anterior portion of the spinal canal. Decompression of the spinal canal can be FIG. -B Preoperative computed-tomography scan. THE JOURNAL OF BONE AND JOINT SURGERY

13 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 81 FIG. -C FIG. -D Computed tomography scans made twelve months after anterior decompression and arthrodesis with the Mark-II Kaneda device. Neurological recovery was complete, but a pseudarthrosis developed because of insufficient resection of the crushed vertebral body. The iliac-crest strut graft had been improperly positioned as it had not been placed beyond the contralateral pedicle (arrows), and it caused asymmetrical axial loading and breakage of the screw. Posterior arthrodesis with instrumentation was subsequently performed, and there was a solid fusion anteriorly and posteriorly six months after that operation. non-structural graft through the pedicle provides any additional support to the anterior column, which might collapse with early loading before incorporation of the graft. With a longer duration of follow-up and a larger series, it is possible that the expected failure of instrumentation and loss of correction of the kyphosis due to an unstable anterior column would become evident. Newer instrumentation systems that include pedicle screws have allowed a decrease in the number of fused segments and greater correction of kyphosis. Despite these advantages, failure to support the anterior spinal column after posterior correction and instrumentation has led to the failure of the posterior spinal instrumentation in many patients' 8. The second method of direct decompression is an anterior approach with partial or complete resection of the vertebral body 46. This anterior decompression has to be combined either with anterior stabilization and instrumentation (a one-stage anterior procedure) 14 or with posterior instrumentation and arthrodesis (a combined anterior and posterior procedure) 6. We reviewed the clinical results that have been reported for short-segment pedicle-screw fixation (with the screws placed one level cephalad and one level caudad to the fracture) and for other anterior decompression procedures in the treatment of thoracolumbar burst fractures (Table VIII). The loss of correction of kyphosis and the rate of failure of instrumentation were greater in the series that had fixation with pedicular 5, ,. screws than in our series. The mean loss of correction of kyphosis ranged from to 1 degrees in the reported series that we reviewed, whereas the mean loss of correction in our series was only 1 degree. The rate of failure of posterior instrumentation ranged from 9 to 54 per cent in the other series, whereas the rate was 6 per cent in the present report. Failure of pedicle screw fixation included breakage, bending, or loosening of the screw because of inadequate support of the anterior column 189. Despite the high rates of failure of the instrumentation in the series that had pedicle screw fix- VOL. 79-A, NO. 1, JANUARY 1997

14 8 KIYOSHI KANEDA ET AL. ation, the rate of non-union was surprisingly low ( per cent) except for that reported by Ebelke et al. (15 per cent) 1. The rate of failure of the Kaneda device depends on proper positioning of the anterior strut graft consisting of tricortical iliac-crest bone and two or three sections of rib. Biomechanical studies of the Kaneda device have shown adequate stability for most loading situations 1181,4. With respect to height, body weight, and duration of hospitalization after the operation, we detected no significant difference (with the numbers available) between the group that had a solid fusion and the group that had a pseudarthrosis. All pseudarthroses occurred in patients who had had poor placement of the anterior strut graft. The graft had not provided stable and symmetrical anterior load-sharing in the spinal column because of placement of the cortical portion of the iliac-crest strut graft on the same side as the Kaneda device. Consequently, we think that one of the most important factors that cause pseudarthrosis is the use of poor technique for the placement of the anterior strut bone graft (Figs. -A through -D). The Kaneda device relies directly on load transmission through a stout, strong tricortical iliac-crest graft for secure fixation. Since 1987, we have used our present technique of placement of the anterior strut graft with the tricortical portion beyond the contralateral pedicle (Fig. 1-F) in fifty-one patients; pseudarthrosis developed in only one patient. Failure of the Kaneda device may be more of a problem for heavier, non-japanese populations if anterior strut-grafting does not provide adequate supplemental support. We also noted that a larger percentage of pseudarthroses occurred with burst fractures of the fourth lumbar vertebra (four of five patients). The increased rate of pseudarthrosis at this level is most likely related to the difficulty in providing a sufficient amount of bone graft as well as to the large strut graft that is needed to bridge the third, fourth, and fifth lumbar vertebrae. The location of the fourth lumbar vertebral body and the shape of the fifth lumbar vertebral body make instrumentation technically more demanding. Because of the high rate of non-union of burst fractures of the fourth lumbar vertebra, we have not treated this fracture with anterior fixation since In our series, the most important predictive factor with regard to neurological recovery was an injury involving the epiconus or conus medullaris. For patients who had such an injury, a complete lack of bladder function with loss of sensation to pinprick in the perineal area preoperatively was indicative of a poor prognosis for recovery of bladder function. Complete paralysis of the bladder associated with incomplete sensation of pain in the perineal area was associated with a better prognosis for recovery of bladder function after decompression. It is important to note that, although the operation was performed more than forty-eight hours after the injury in 14 (95 per cent) of our patients, the neurological recovery was acceptable. Thus, we believe that when anterior decompression of the spinal canal is performed in patients who have a thoracolumbar burst fracture with neurological deficits, recovery of neurological function is not always dependent on the timing of the operative intervention. The goals of an operation for a thoracolumbar burst fracture with associated neurological deficits should be decompression of the spinal canal, restoration of spinal alignment, and successful arthrodesis of the injured spinal segments. These goals were accomplished in more than 9 per cent of our patients, who had low perioperative and postoperative rates of complications. We attribute our excellent results to the use of the anterior approach, the design of the Kaneda device, and our close attention to operative details. Nom The authors wish to acknowledge Paul C. McAfee, M.D., of the Spine and Scoliosis Center in Baltimore. Maryland, for his help in reviewing and editing this manuscript. References 1. An, H. S.; Lim, T. H.; You, J. W.; Hong, J. H.; Eck, J.; and McGrady, L.: Biomechanical evaluation of anterior thoracolumbar spinal instrumentation. Spine, : , Asano, S.; Kaneda, K.; Satoh, S.; Abumi, K.; Hashimoto, T.; and Fujiya, M.: Reconstruction of an iliac crest defect with a bioactive ceramic prosthesis. European Spine J., :9-44, Bauer, R. D., and Errico, T. J.: Thoracolumbar spine injuries. In Spinal Trauma, pp Edited by T. J. Errico, R. D. Bauer, and T. Waugh. Philadelphia, J. B. Lippincott, Been, H. D.: Anterior decompression and stabilization of thoracolumbar burst fractures by the use of the Slot-Zielke device. Spine, 16: 7-77, Benson, D. R.; Burkus, J. K.; Montesano, P. X.; Sutherland, T. B.; and McLain, R. F.: Unstable thoracolumbar and lumbar burst fractures treated with the AO fixateur interne../. Spinal Disord., 5:5-4, Bradford, D. S., and McBride, G. G.: Surgical management of thoracolumbar spine fractures with incomplete neurologic deficits. Clin. Orthop., 18:1-16, Carl, A. L.; Tromanhauser, S. G.; and Roger, D. J.: Pedicle screw instrumentation for thoracolumbar burst fractures and fracturedislocations. Spine, 17(8S): S17-S4, Crowe, P., and Gertzbein, S. D.: Spinal canal clearance in burst fractures using the AO internal fixator. Read at the Annual Meeting of the Scoliosis Research Society, Amsterdam, The Netherlands, Sept., Crutcher, J. P., Jr.; Anderson, P. A.; King, H. A.; and Montesano, P. X.: Indirect spinal canal decompression in patients with thoracolumbar burst fractures treated by posterior distraction rods. J. Spinal Disord., 4: 9-48, Denis, E: The three column spine and its significance in the classification of acute thoracolumbar spinal injuries. Spine, 8:817-81, Denis, E: Spinal stability as defined by the three-column spine concept in acute spinal trauma. Clin. Orthop., 189:65-76,1984. THE JOURNAL OF BONE AND JOINT SURGERY

15 ANTERIOR DECOMPRESSION AND STABILIZATION WITH THE KANEDA DEVICE 8 1. Dunn, H. K.: Anterior stabilization of thoracolumbar injuries. Clin. Orthop., 189:116-14, Ebelke, D. K.; Asher, M. A.; Neff, J. R.; and Kraker, D. P.: Survivorship analysis of VSP spine instrumentation in the treatment of thoracolumbar and lumbar burst fractures. Spine, 16(8S): S48-S4, Esses, S. I.; Botsford, D. J.; and Kostuik, J. P.: Evaluation of surgical treatment for burst fractures. Spine, 15:667-67, Fredrickson, B. E.; Mann, K. A.; Yuan, H. A.; and Lubicky, J. P.: Reduction of the intracanal fragment in experimental burst fractures. Spine, 1:67-71, Gaines, R. W., Jr.; Carson, W. L.; Satterlee, C. C; and Groh, G. I.: Experimental evaluation of seven different spinal fracture internal fixation devices using nonfailure stability testing. The load-sharing and unstable-mechanism concepts. Spine, 16:9-99, Gertzbein, S. D.: Scoliosis Research Society. Multicenter spine fracture study. Spine, 17: 58-54, Gurr, K. R.; McAfee, P. C; and Shih, C.-M.: Biomechanical analysis of anterior and posterior instrumentation system after corpectomy. A calf-spine model. /. Bone and Joint Surg., 7-A: , Sept Haas, N.; Blauth, M.; and Tscherne, H.: Anterior plating in thoracolumbar spine injuries. Indication, technique, and results. Spine, 16 (S):S1-S111, Hardaker, W. T., Jr.; Cook, W. A., Jr.; Friedman, A. H.; and Fitch, R. D.: Bilateral transpedicular decompression and Harrington rod stabilization in the management of severe thoracolumbar burst fractures. Spine, 17:16-171, Hashimoto, T.; Kaneda, K.; and Abumi, K.: Relationship between traumatic spinal canal stenosis and neurologic deficit in thoracolumbar burst fractures. Spine, 1:168-17, Kaneda, K.: Anterior approach and Kaneda instrumentation for lesions of the thoracic and lumbar spine. In The Textbook of Spinal Surgery, edited by K. H. Bridwell and R. L. DeWald. Vol., pp Philadelphia, J. B. Lippincott, Kaneda, K.; Abumi, K.; and Fujiya, M.: Burst fractures with neurologic deficits of the thoracolumbar-lumbar spine. Results of anterior decompression and stabilization with anterior instrumentation. Spine, 9: , Kostuik, J. P.: Anterior fixation for burst fractures of the thoracic and lumbar spine with or without neurological involvement. Spine, 1: 86-9, McAfee, P. C: Complications of anterior approaches to the thoracolumbar spine. Emphasis on Kaneda instrumentation. Clin. Orthop., 6:11-119, McAfee, P. C; Bohlman, H. H.; and Yuan, H. A.: Anterior decompression of traumatic thoracolumbar fractures with incomplete neurological deficit using a retroperitoneal approach. J. Bone and Joint Surg., 67-A: 89-14, Jan McAfee, P. C; Yuan, H. A.; and Lasda, N. A.: The unstable burst fracture. Spine, 7:65-7, McLain, R. F.; Sparling, E.; and Benson, D. R.: Early failure of short-segment pedicle instrumentation for thoracolumbar fractures. A preliminary report. J. Bone and Joint Surg., 75-A: , Feb McNamara, M. J.; Stephens, G. C; and Spengler, D. M.: Transpedicular short-segment fusions for treatment of lumbar burst fractures. / Spinal Disord., 5:18-187,199.. Sasso, R. C; Cotler, H. B.; and Reuben, J. D.: Posterior fixation of thoracic and lumbar spine fractures using DC plates and pedicle screws. Spine, 16(S): S14-S19, Shono, Y.; McAfee, P. C; and Cunningham, B. W.: Experimental study of thoracolumbar burst fractures. A radiographic and biomechanical analysis of anterior and posterior instrumentation systems. Spine, 19: , Stephens, G. C; Devito, D. P.; and McNamara, M. J.: Segmental fixation of lumbar burst fractures with Cotrel-Dubousset instrumentation. / Spinal Disord., 5: 44-48,199.. Viale, G. L.; Silvestro, C; Francaviglia, N.; Carta, E; Bragazzi, R.; Bernucci, C; and Maiello, M.: Transpedicular decompression and stabilization of burst fractures of the lumbar spine. Surg. Neurol, 4:14-111, Zdeblick, T. A.; Shirado, O.; McAfee, P. C; de Groot, H.; and Warden, K. E.: Anterior spinal fixation after lumbar corpectomy. A study in dogs. /. Bone and Joint Surg., 7-A: 57-54, April VOL. 79-A, NO. 1, JANUARY 1997