CHAPTER 14

EXTRACOELOMIC MINI APPROACH FOR ANTERIOR RECONSTRUCTIVE SURGERY OF THE THORACOLUMBAR AREA
Hesham ElSaghir, M.D.
Wirbelsulenchirurgie, Bad Berka Spine Center, Zentralklinik Bad Berka, Bad Berka, Germany Reprint requests: Hesham ElSaghir, M.D., 1 Oberarzt Wirbelsulenchirurgie, Zentralklinik Bad Berka, Robert Koch Allee 9, 99437 Bad Berka, Germany. Email: sekort@Zentralklinik-bad-berka.de

OBJECTIVE: An extracoelomic mini approach is introduced as a less invasive technique for surgery of the thoracolumbar area performed via the anterior approach. METHODS: Twenty-one patients with spinal pathological findings at the thoracolumbar junction were assessed. The reasons for surgery were as follows: burst fracture of the first lumbar vertebra (n 5), degenerative disc at L1L2 (n 4), spondylodiscitis at L1L2 (n 8) and at T11L1 (n 1), pathological fracture of the first lumbar vertebra (n 2), and pseudarthrosis at T11L1 after failed reconstruction (n 1). The anterior surgical procedure was performed via an extracoelomic mini approach. Intersomatic fusion was performed in 13 patients, corpectomy and bone grafting in 4, corpectomy and vertebral replacement with titanium cage packed with bone cement in 3, and removal of a cage in a failed fusion and bridging the defect with a strut bone graft in 1. Posterior instrumentation of the affected segment was performed in the same sitting. RESULTS: The mean standard deviation of operative time of the anterior procedure was 101.2 36.5 minutes. The mean blood loss during the anterior procedure was 724 483.5 ml. The procedure was safe. No pseudarthrosis was encountered, and the reconstructed bone was stable in the three patients in whom bone cement was used. CONCLUSION: The extracoelomic mini approach is less invasive; it results in less incisional morbidity, and it avoids opening the pleural and peritoneal cavities.
KEY WORDS: Extrapleural approach, Mini approach, Thoracolumbar spine
Neurosurgery 51[Suppl 2]:118122, 2002 DOI: 10.1227/01.NEU.0000031001.04474.F7 www.neurosurgery-online.com

he thoracolumbar area is a common site for traumatic and nontraumatic spinal disorders. As a result of the unique anatomic features in this region, with the diaphragm sandwiched between the pleura and the peritoneum, a thoracolumbophrenotomy has been the standard approach for this area (9). The technique entails opening the thoracic cavity along one of the lower ribs, cutting the diaphragm 10 to 15 mm from the peripheral costal insertion, and moving the peritoneal sac away from the vertebral column. This yields excellent anterior exposure of the lower thoracic spine and the lumbar spine down to the fourth lumbar vertebra (2). For a short segment problem, however, the thoracolumbophrenotomy is too extensive. A review of the literature reflects the trend for a search for less invasive approaches to the thoracolumbar region (7, 11, 12). The most famous one is that described by Mirbaha (11): an extrapleural retroperitoneal approach in which the diaphragm is completely freed from the bed of the 12th rib. Moskovich et al. (12) modified the complicated Mirbahas approach in a way that simplifies the costophrenic detachment by performing the dissection on both sides of the diaphragm. However, both techniques are still

extensive and entail wide costophrenic detachment. Performing the dissection in the supraphrenic space with a lack of sufficient protection to the peeled-off pleura increases the likelihood of accidental injury to the pleura. With the improvements in access technology, interest in approaching the thoracolumbar junction with the aid of the endoscope has evolved (3, 10). Although this step is a real advantage, the commonly required mini thoracotomy requires inserting a chest tube. The aim of this prospective study is twofold: to introduce an extracoelomic mini approach to the thoracolumbar area, and to study the results of its use in reconstruction of the thoracolumbar area.

PATIENTS AND METHODS

Operative Technique
The operation is performed while the patient is under general anesthesia. The patient is positioned in the lateral decubitus and is allowed to tilt 10 to 15 degrees toward the supine position. This facilitates anterior decompression and permits

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instrumentation of the involved segment. The operating table is arched to draw the lower ribs away from the iliac crest to elongate the lateral aspect of the thorax. A left-sided approach is preferred because it permits easier identification and thus protection of the aorta. In addition, the parenchymatous organs on the left side are not bulky and are easy to retract medially. However, if the abnormality is predominantly located on the right side, a right-sided approach is generally indicated. A mini-incision not longer than 5 cm is made opposite to the abnormality to be exposed. The direction of the incision is parallel to the part of the rib that gives direct access to the affected segment. This is usually the 10th rib for the T12L1 level and the 11th rib for the L1L2 level. The periosteum over the selected rib is incised and elevated. Further separation of the periosteum is performed with the aid of a Cobb elevator. A segment of the rib (approximately 56 cm) is excised. The main purpose of this step is to facilitate retraction of the diaphragm and the soft tissues in a cranial direction. The diaphragm at the bed of the excised rib is left intact, and the exposure is performed by splitting the abdominal muscles at a slightly lower level (approximately 23 cm). The retroperitoneal space is entered and the retroperitoneal fat is mobilized medially. With the aid of three retractors, the peritoneal sac is kept medial and the diaphragm is retracted cranially. This will expose the psoas muscle, vertebral bodies, intervertebral discs, and the medial arcuate ligament. The latter is stretched across the proximal end of the psoas muscle from the crura to the transverse process of L1 and provides attachment to the diaphragm. The upper part of the psoas is dissected and retracted in a posterolateral direction; this exposes the L1L2 level. Further retraction of the medial arcuate ligament and the diaphragm in a cranial direction gives access to the T12L1 disc (Fig. 14.1). Blunt dissection is continued by a sponge-stick to expose the body of the 12th thoracic vertebra. Care must be taken not to injure the parietal pleura covering the body of the 12th thoracic vertebra. With gentleness and patience, the parietal pleura can be peeled off with relative ease. The operation via the anterior approach is then performed in a traditional way. Angled surgical instruments, wound retractors, and a strong light source facilitate performing the anterior operation through a narrow field. At the end of the reconstructive procedure, the medial arcuate ligament is approximated to the adjoining part of the psoas muscle. Overlooking accidental tears of the pleura can be avoided by asking the anesthetist to inflate the lungs at the time the surgical wound is closed. A suction tube is inserted in the retroperitoneal space. The wound is then closed in layers.

Patient Population
From June 1998 to August 1999, 21 patients (12 men, 9 women) with spinal pathological findings between T11 and L2 underwent anterior short segment reconstruction of the spine utilizing the aforementioned approach. The preoperative diagnosis was as follows: Burst fracture of the L1 in five patients, degenerative disc L1L2 in four, spondylodiscitis L1L2 in eight, spondylitis T11L1 in one, pathological fracture of L1 in two, and pseudoarthrosis T11L1 after corpectomy of T12 in

FIGURE 14.1. A, operative photograph showing the anterior mini approach. 1. Diaphragm. 2. Psoas muscle. 3. Intervertebral disc; L1L2 hidden by large vertebral osteophytes. 4. Intervertebral disc, T12L1. 5. Vertebral body L1. 6. Medial arcuate ligament. 7. Segmental vessels. 8. Retroperitoneal fat. 9. Retractor. 10. Cobb. B, schematic drawing of the relevant anatomical structures shown in the photograph.

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one (Table 14.1). Causative organisms of spinal infections were Staphylococcus aureus in four, Staphylococcus epidermitis in two, and Enterococcus faecalis in one. In two patients, the causative organism was not isolated. Anterior decompression was indicated and was performed in four patients. Intersomatic fusion by use of iliac bone grafting was performed in 13 patients and corpectomy and reconstruction by use of iliac graft augmented by rib grafting in four. In three patients, corpectomy and replacement with titanium cage packed by bone cement was performed. In the remaining patient with symptomatic pseudarthrosis after corpectomy, removal of the anterior device was performed, and iliac bone grafting was used for the anterior reconstruction. Anterior instrumentation (rod-screw system) was performed in five patients (Table 14.2). In all instances, posterior instrumentation of the affected segment or segments without fusion was performed in the same sitting. The mean standard deviation of the sagittal angle of the affected segment at the preoperative period was 2.8 3.1 degrees. The period of follow-up ranged from 9 months to 20 months (12.4 2.1 mo).

TABLE 14.2. Type of anterior reconstructive procedure Anterior reconstructive procedure Intersomatic fusion Corpectomy, bone grafting, and anterior stabilization Corpectomy, replacement with cage and bone cement Extraction of cage, bone grafting, and anterior fixation No. of patients 13 4 3 1

RESULTS
The operative time required for the anterior reconstructive procedure ranged from 45 minutes to 200 minutes (101.2 36.5 min). The blood loss during the anterior operation ranged from 100 to 3000 ml (724.8 483.5 ml). All the anterior wounds healed with primary intention. Superficial wound infection of the posterior wound occurred in one patient, who responded to local wound care and systemic administration of antibiotic. The postoperative course was complicated by a chest infection in one patient. This patient died 3 months after the operation as a result of associated comorbidity. In 19 patients, it was possible to expose and reconstruct the affected segment without injuring the parietal pleura. Accidental injury to the parietal pleura was encountered in the remaining two. In one of them, the tear occurred during subperiosteal exposure of the 10th rib, and in the other, during exposure of the body of T12. In both, the pleural tear was not handled, and a chest tube connected to an underwater seal suction was inserted. Decompression of the dura was demanding in one patient because of difficulty in removing a retropulsed bony fragment (Fig. 14.2).
TABLE 14.1. Preoperative diagnosis Preoperative diagnosis Burst fracture L1 Degenerated L1L2 disc Spondylodiscitis L1L2 Spondylodiscitis T11L1 Pathological fracture L1 Pseudarthrosis after corpectomy T12 No. of patients 5 5 8 1 1 1 FIGURE 14.2. Representative studies of a burst fracture of L1. A, lateral x-ray obtained in the patient before the operation. B, preoperative axial computed tomographic scan obtained in the same patient. Note the encroachment on the spinal canal by a displaced bony fragment. C, postoperative lateral x-ray. Note extension of the anterior fixation between T12 and L2. D, postoperative photograph of the same patient. Note the size and site of the mini incision. E, postoperative lateral x-ray 1 year after the operation demonstrating a successful bisegmental fusion.

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Stable reconstruction was achieved in all patients. Healing occurred in the 17 patients in whom bone grafting was used (Figs. 14.2 and 14.3). In the three patients in whom bone cement was applied, no metal breakage occurred, and sagittal plane analysis revealed a sinking in of the cage in one of them. Metal failure of the anterior instrumentation was observed in two patients (screw breakage in one and rod breakage in the other) and was associated with increased segmental kyphosis. The mean of the angle in the sagittal plane improved from 2.8 degrees at the preoperative period to 1.3 0.2 degrees. After a mean follow-up of 12.4 months, the angle reached 1.9 1.7 degrees. Apart from reversible thoracic dermatome dyskinesia in two patients, no neurological deficits attributed to the surgical procedure were encountered. the dissection that is performed on both sides of the diaphragm. Confluence of the extrapleural and the retroperitoneal spaces is achieved by detaching the diaphragm from its insertion on the chest wall and the crus from the side of the spine. For only a limited operation at the thoracolumbar junction, both approaches are extensive and time-consuming. Costophrenic detachment must be performed, and the possibility of accidental injury to the pleura is still present. The mini extracoelomic approach I present here avoids all these disadvantages. The dissection is reduced to the minimum required for approaching the target. Only a segment of the rib opposite the lesion is removed, and costophrenic detachment is not needed. Performing dissection in the infraphrenic space leaves the diaphragm as a septum protecting the parietal pleura. The approach affords access of the thoracolumbar spine up to the T11T12 disc. By avoiding the peritoneal and pleural cavities, the postoperative care is less complicated and the morbidity is proportionately less. The use of this approach in 21 patients revealed that the approach is safe, and performing the anterior reconstruction was successful. The results of this study validate the recommendations of several authors (1, 4, 8, 13, 14) who suggest making use of access technology that enables the surgeon to apply surgical techniques with which they are familiar to the task of performing regular wide open-spine surgery.

DISCUSSION
A review of the literature reveals that the first description of an extrapleural retroperitoneal approach was that provided by Fey (5). A report on the use of a similar approach for sympathectomy was published by Francioli (6). In the field of spinal surgery, Mirbahas (11) approach is probably the most popular extrapleural retroperitoneal one for the thoracolumbar area. The approach starts from the T9 spinous process and passes over the spinous processes of T10, T11, and T12, follows the course of the 12th rib to 2.5 cm above and behind the anterior superior iliac crest. The following muscles are transected from superficial to deep: latissimus dorsi, external oblique, serratus posterior inferior, internal oblique, transversus abdominis, sacrospinalis, and multifidus muscle mass. The approach involves resection of the medial half of the 12th rib and the left crus of the diaphragm, release of the costal insertion of the quadratus lumborum, and detachment of the lateral arcuate ligament and the lumbocostal ligament of Henle. The parietal pleura is then peeled off to expose the thoracolumbar junction. Moskovich et al. (12) described another approach in
FIGURE 14.3. Representative studies of spondylodiscitis at the L1L2 level. A, T2-weighted midsagittal magnetic resonance image (MRI). B, T1-weighted midsagittal MRI. C, T1-weighted midsagittal MRI after gadolinium diethylenetriamine penta-acetic acid. D, postoperative lateral x-ray. E, lateral x-ray 1 year after the operation showing bony healing with mild segmental kyphosis. F, postoperative clinical photograph obtained in the same patient 1 year after the operation. Note the site and size of the scar.

CONCLUSION
The approach I describe here can supplant the traditionally extensive approaches used for limited thoracolumbar surgery

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involving maximally two segments. Clearly, this approach is not appropriate for extensive damage that requires extensive repair, and thus a wider field. Greater care must be taken to preserve tissues, and the surgeon must avoid inflicting damage to tissues involved in the repair process. The surgeon must select this approach from many, ensuring that the appropriate and the most conservative operation for a specific patient will be chosen.
7. Hodgson AR, Stock FS: Anterior spinal fusion: A preliminary communication on the radical treatment of Potts disease and Potts paraplegia. Br J Surg 44:266275, 1956. 8. Mayer HM: A new microvascular technique for minimally invasive anterior lumbar interbody fusion. Spine 22:691700, 1997. 9. McAfee PC, Zdeblick TA: Tumors of the thoracic and lumbar spine: Surgical treatment via the anterior approach. J Spinal Disord 2:145154, 1989. 10. McAfee PC, Regan JR, Zdeblick T, Zuckerman J, Picetti GD III, Heim S, Geis WP, Fedder IL: The incidence of complications in endoscopic anterior thoracolumbar spinal reconstructive surgery. Spine 20:16231632, 1995. 11. Mirbaha MM: Anterior approach to the thoraco-lumbar junction of the spine by a retroperitoneal-extrapleural technic. Clin Orthop 91:4147, 1973. 12. Moskovich R, Benson D, Zhang ZH, Kabins M: Extracoelomic approach to the spine. J Bone Joint Surg Br 75B:886893, 1993. 13. Roh SW, Kim DH, Cardoso AC, Fessler RG: Endoscopic foraminotomy using MED system in cadaveric specimens. Spine 25:260264, 2000. 14. Zucherman JF, Zdeblick TA, Baily SA, Mahvi D, Hsu KY, Kohrs D: Instrumented laparoscopic spinal fusion. Spine 20:20292035, 1995.

REFERENCES
1. Aebi M, Steffen T: Synframe: A preliminary report. Eur Spine J 9[Suppl 1]:4450, 2000. 2. Bauer R, Kerschbaumer F, Porsel S: Operative Zugangswege in Orthopdie und Traumatologie. Stuttgart, Georg Thieme Verlag, 1986, pp 3757. 3. Bhm H, Elsaghir H: Dorsale Stabilisierungen, in Reichel H, Zwipp H, Hein W (eds): Wirbelsulenchirurgie: Standortbestimmung und Trends. Darmstadt, Steinkopff, 2000, pp 102105. 4. Bhm H, ElSaghir H: Minimally invasive ventral release and endoscopic ventral instrumentation in scoliosis [in German]. Orthopade 29:535542, 2000. 5. Fey B: Labord du rein voie thoraco-abodominale. Urologicale Clin Necker 5:169178, 1925. 6. Francioli P: Voies dacces dans les sympathectomies lombarie et lombothoracique. Helv Chir Acta 18:536556, 1951.

Acknowledgments
I thank Dr. Heinrich Bhm, my friend and chief of Bad Berka Spine Center in the Zentralklinik Bad Berka. His minimal invasive operations and ideas motivated me to introduce the extracoelomic mini approach.

From a notebook of Leonardo da Vinci, showing the nerve plexus throughout the body.

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