[Thoracoscopy-guided management of the "anterior column". Methods and results]

Six-year outcome of thoracoscopic ventral spondylodesis after unstable incomplete cranial burst fractures of the thoracolumbar junction: ventral versus dorso-ventral strategy

PURPOSE

The purpose of this study is to determine the long term-results after thoracoscopic spondylodesis particularly with respect to a ventral versus dorso-ventral treatment strategy.

METHODS

In this prospective cohort study, a follow-up examination was performed in 19 patients (seven men, 12 women, average age: 37.7 years, follow-up rate: 79 %), six years after ventral thoracoscopic spondylodesis of unstable, incomplete burst fractures. Nine patients received a ventral monosegmental spondylodesis with iliac crest bone graft. The other ten cases were treated dorso-ventrally, five undergoing a ventral monosegmental treatment with iliac crest bone graft; the other five a ventral bisegmental treatment with expandable titanium cage.

RESULTS

The complication rate was 15.7 %, the rate of revision of 10.5 %. No complication was related to the ventral thoracoscopic approach, whereas all of them were related to the iliac crest bone graft. The operative bisegmental kyphotic reduction was higher in the dorso-ventrally treated group. Afterwards, the loss of reduction was similar in both study groups. The mean VAS spine score summed up to more than 80 in both groups. The mean PCS scores were comparable to a normal healthy collective of the same age.

CONCLUSIONS

The ventral thoracoscopic approach to the spine seems to be a safe therapeutic strategy. A dorso-ventral treatment concept goes along with a higher operative reduction potential.

Outcome after thoracoscopic ventral stabilisation of thoracic and lumbar spine fractures

BACKGROUND AND PURPOSE

Thoracoscopic-assisted ventral stabilisation for thoracolumbar fractures has been shown to be associated with decreased recovery time and less morbidity when compared with open procedures. However, there are a limited number of studies evaluating late clinical and radiological results after thoracoscopic spinal surgery.

METHODS

We performed an analysis of the late outcomes of thoracolumbar fractures after minimally invasive thoracoscopic ventral instrumentation. Between August 2003 and December 2008, 70 patients with thoracolumbar fractures (T5-L2) underwent ventral thoracoscopic stabilisation. Tricortical bone grafts, anterior plating systems (MACS-System), and cage implants were used for stabilisation. Outcomes measured include radiologic images (superior inferior endplate angle), Visual Analogue Scale (VAS), VAS Spine Score, quality of life scores SF-36 and Oswestry Disability Index (ODI).

RESULTS

Forty seven patients (67%, 47 out of 70) were recruited for the follow up evaluation (2.2 ± 1.5 years). Lower VAS Spine scores were calculated in patients with intra- or postoperative complications (44.7 (± 16.7) vs. 65.8 (± 24.5), p=0.0447). There was no difference in outcome between patients treated with bone graft vs. cage implants. Loss of correction was observed in both bone graft and titanium cage groups.

INTERPRETATION

The present study demonstrates diminished long-term quality of life in patients treated with thoracoscopic ventral spine when compared with the outcome of german reference population. In contrast to the other patients, those patients without intra-operative or post-operative complications were associated with improved outcome. The stabilisation method (bone graft versus spinal cage) did not affect the long-term clinical or radiographic results in this series.

Operative treatment of 733 patients with acute thoracolumbar spinal injuries: comprehensive results from the second, prospective, Internet-based multicenter study of the Spine Study Group of the German Association of Trauma Surgery

The second, internet-based multicenter study (MCSII) of the Spine Study Group of the German Association of Trauma Surgery (Deutsche Gesellschaft für Unfallchirurgie) is a representative patient collection of acute traumatic thoracolumbar (T1-L5) injuries. The MCSII results are an update of those obtained with the first multicenter study (MCSI) more than a decade ago. The aim of the study was to assess and bring into focus: the (1) epidemiologic data, (2) surgical and radiological outcome, and (3) 2-year follow-up (FU) results of these injuries. According to the Magerl/AO classification, there were 424 (57.8%) compression fractures (A type), 178 (24.3%) distractions injuries (B type), and 131 (17.9%) rotational injuries (C type). B and C type injuries carried a higher risk for neurological deficits, concomitant injuries, and multiple vertebral fractures. The level of injury was located at the thoracolumbar junction (T11-L2) in 67.0% of the case. 380 (51.8%) patients were operated on by posterior stabilization and instrumentation alone (POSTERIOR), 34 (4.6%) had an anterior procedure (ANTERIOR), and 319 (43.5%) patients were treated with combined posteroanterior surgery (COMBINED). 65% of patients with thoracic (T1-T10) and 57% with lumbar spinal (L3-L5) injuries were treated with a single posterior approach (POSTERIOR). 47% of the patients with thoracolumbar junction (T11-L2) injuries were either operated from posterior or with a combined posterior-anterior surgery (COMBINED) each. Short angular stable implant systems have replaced conventional non-angular stable instrumentation systems to a large extent. The posttraumatic deformity was restored best with COMBINED surgery. T-spine injuries were accompanied by a higher number and more severe neurologic deficits than TL junction or L-spine injuries. At the same time T-spine injuries showed less potential for neurologic recovery especially in paraplegic (Frankel/AISA A) patients. 5% of all patients required revision surgery for perioperative complications. Follow-up data of 558 (76.1%) patients were available and collected during a 30-month period from 1 January 2004 until 31 May 2006. On average, a posterior implant removal was carried out in a total of 382 COMBINED and POSTERIOR patients 12 months after the initial surgery. On average, the rehabilitation process required 3-4 weeks of inpatient treatment, followed by another 4 months of outpatient therapy and was significantly shorter when compared with MCSI in the mid-1990s. From the time of injury until FU, 80 (60.6%) of 132 patients with initial neurological deficits improved at least one grade on the Frankel/ASIA Scale; 8 (1.3%) patients deteriorated. A higher recovery rate was observed for incomplete neurological injuries (73%) than complete neurological injuries (44%). Different surgical approaches did not have a significant influence on the neurologic recovery until FU. Nevertheless, neurological deficits are the most important factors for the functional outcome and prognosis of TL spinal injuries. POSTERIOR patients had a better functional and subjective outcome at FU than COMBINED patients. However, the posttraumatic radiological deformity was best corrected in COMBINED patients and showed significantly less residual kyphotic deformity (biseg GDW -3.8° COMBINED vs. -6.1° POSTERIOR) at FU (p = 0.005). The sagittal spinal alignment was better maintained when using vertebral body replacement implants (cages) in comparison to iliac strut grafts. Additional anterior plate systems did not have a significant influence on the radiological FU results. In conclusion, comprehensive data of a large patient population with acute thoracolumbar spinal injuries has been obtained and analyzed with this prospective internet-based multicenter study. Thus, updated results and the clinical outcome of the current operative treatment strategies in participating German and Austrian trauma centers have been presented. Nevertheless, it was not possible to answer all remaining questions to contradictory findings of the subjective, clinical outcome and corresponding radiological findings between different surgical subgroups. Randomized-controlled long-term investigations seem mandatory and the next step in future clinical research of Spine Study Group of the German Trauma Society.

[Operative treatment of traumatic fractures of the thorax and lumbar spine. Part II: surgical treatment and radiological findings]

The Spine Study Group (AG WS) of the German Trauma Association (DGU) presents its second prospective Internet-based multicenter study (MCS II) for the treatment of thoracic and lumbar spinal injuries. This second part of the study report focuses on the surgical treatment, course of treatment, and radiological findings in a study population of 865 patients. A total of 158 (18,3%) thoracic, 595 (68,8%) thoracolumbar, and 112 (12,9%) lumbar spine injuries were treated. Of these, 733 patients received operative treatment (OP group). Fifty-two patients were treated non-operatively and 69 patients were treated with kyphoplasty/vertebroplasty without additional instrumentation (Plasty group). In the OP group, 380 (51.8%) patients were instrumented from a posterior (dorsal) position, 34 (4.6%) from an anterior (ventral) position, and 319 (43.5%) cases with a combined posteroanterior procedure. Angular stable internal spine fixator systems were used in 86-97% of the cases for posterior and/or combined posteroanterior procedures. For anterior procedures, angular stable plate systems were used in a majority of cases (51.1%) for the instrumentation of mainly one or two segment lesions (72.7%). In 188 cases (53,3%), vertebral body replacement implants (cages) were used and were mainly implanted via endoscopic approaches (67,4%) to the thoracic spine and/or the thoracolumbar junction. The average operating time was 152 min in posterior-, 208 min in anterior-, and 298 min in combined postero-anterior procedures (p<0,001). The average blood loss was highest in combined operations, measuring 959 ml vs. 650 ml in posterior vs. 534 ml in anterior operations (p<0,001).Computer-assisted intraoperative navigation systems were used in 95 cases. At the time of hospital admission, 58,7% of the patients had spinal canal narrowing of an average of 36% (5-95%) at the level of their injury. The average spinal canal narrowing in patients with a complete spinal cord injury (Frankel/ASIA A) was calculated to be 70%, vs. 50% in patients with incomplete neurologic deficits (Frankel/ASIA B-D), and 20% in patients without neurologic deficits (Frankel/ASIS E; p<0,001). The average procedure in the plasty treatment subgroup was 50 min (18-145 min) to address one (n=59) or two (n=10) injured vertebral bodies. In patients with nonoperative treatment mainly three-point-corsets (n=36) were administered for a duration of 6-12 weeks. During their hospital stay 93 of 195 (44,7%) patients with initial neurologic deficits improved at least one Frankel/ASIA grade until the day of discharge. Two patients (0,2%) showed a neurologic deterioration. The highest rate of complete spinal cord injury (n=36, 23%) was associated with thoracic spine injuries. Nine (1%) patients died during the initial course of treatment. A total of 105 (14,3%) cases with intraoperative (n=56) and/or postoperative complications (n=69) were registered. The most common intraoperative complication was bleeding (n=35, 4,8%). A higher relative frequency of intraoperative complications was noticed in combined (n=34, 10,7%) vs. isolated posterior (n=22, 5,9%; p=0,021) procedures. The most common postoperative complication was associated with wound healing problems in 14 (1,9%) patients. Except in the non-operative treatment subgroup, a correction of the posttraumatic measured radiological deformity was achieved to a different extent within every treatment subgroup. There were no statistically significant differences between the postoperative radiological results of the treatment subgroups (dorsal vs. combination), taking into consideration the influence of relevant parameters such as different fracture types, patient age, and the amount of posttraumatic deformity (p=0,34, ANOVA).

Two column lesions in the thoracolumbar junction: anterior, posterior or combined approach? A comparative biomechanical in vitro investigation

There are various surgical techniques for the treatment of spinal fractures in the thoracolumbar region. Several implants have been developed for anterior or posterior instrumentation. Optimal treatment of unstable thoracolumbar osseous and ligamentous injuries remains controversial. To compare the stabilizing effects of an antero-lateral, thoracoscopically implantable plate system (macsTL, Aesculap, Germany) with the stability provided by a fixateur interne (SOCON, Aesculap, Germany), this in vitro investigation examined six human bisegmental (T12-L2) spinal units. Specimens were tested intact, and with simulation of osseous lesions in the anterior and ligamentous lesions in the posterior column (combined A/B-fracture). While loaded in the main anatomical planes such as flexion/extension, left and right lateral bending and left and right axial rotation with a bending moment of 7.5 Nm in a special testing jigs, motion analysis was performed. Quantitative interpretation of the stabilizing effect was achieved using a contactless three-dimensional motion analysis system. Each specimen was tested in four different scenarios: the first step measured movements of intact spinal segments. For the second step, specimens underwent simulation of combined A/B-fracture provided with bisegmental (T12/L2) antero-lateral fixation and bone strut graft from the iliac crest. For the third step, segments were additionally stabilized by the fixateur interne. The last measurement (fourth step) was performed after removing the anterior instrumentation. Range of motion (ROM) values were compared and statistically evaluated. Compared to the intact specimens the anterior instrumentation of the combined lesion, simulated A/B-fracture, leads to a stabilizing effect in flexion/extension and lateral bending. In contrast to these findings the torsional instability increased for the upper segment and bisegmentally. A maximum rigidity, beyond intact values, was registered for each anatomical plane with the combined instrumentation: antero-lateral and fixateur interne. After removing the anterior screw plate system maximum movements, in all segments for flexion/extension and lateral bending, bisegmentally and for the upper segment in axial rotation, were less than ROM values measured with the anterior system only. With respect to these findings a combined ventro-dorsal stabilization procedure should be considered for ligamentous disruptions of the posterior column in combination with A-fractures in the thoracolumbar junction.

Thoracoscopic spine surgery for decompression and stabilization of the anterolateral thoracolumbar spine

The anterior thoracolumbar spine can be exposed via a variety of approaches. Historically, open anterolateral or pos-terolateral approaches have been used to gain access to the anterior thoracolumbar spinal column. Although the exposure is excellent, open approaches are associated with significant pain and respiratory problems, substantial blood loss, poor cosmesis, and prolonged hospitalization. With the increasing use of the endoscope in surgical procedures and recent advances in video-assisted thoracoscopic surgery, minimally invasive thoracoscopic spine surgery has been developed to decrease the morbidity associated with open thoracotomy. The purpose of this article is to illustrate the surgical technique of a minimally invasive thoracoscopic approach to the anterolateral thoracolumbar spine and to discuss its potential indications and contraindications in patients with diseases involving the anterior thoracic and lumbar regions.

Surgical technique and results of endoscopic anterior spinal canal decompression

OBJECT

Decompression of the spinal canal in the management of thoracolumbar trauma is controversial, but many authors have advocated decompression in patients with severe canal compromise and neurological deficits. Anterior decompression, corpectomy, and fusion have been shown to be more reliable for spinal canal reconstruction than posterior procedures; however, traditional anterior-access procedures, thoracotomy, and thoracoabdominal approaches are associated with significant complications. Endoscopy-guided spinal access avoids causing these morbidities, but it has not been shown to yield equivalent results in spinal canal clearance. This study was conducted to demonstrate the effectiveness of endoscopic spinal canal decompression and reconstruction quantitatively by using pre- and postoperative computerized tomography (CT) scanning.

METHODS

Thirty patients with thoracolumbar canal compromise underwent endoscopic anterior spinal canal decompression, interbody reconstruction, and stabilization for fractures (27 cases), and tumor, infection, and severe degenerative disc disease (one case each). The mean follow-up period was 42 months (range 24 months-6 years). Neurological examinations, Frankel grades, radiological studies, and intraoperative findings were prospectively collected. Spinal canal clearance quantified on pre- and postoperative CT scans improved from 55 to 110%. A total of 25% of patients with complete paraplegia and 65% of those with incomplete neurological deficit improved neurologically. The complication rate was 16.7% and included one reintubation, two pleural effusions, one intercostal neuralgia, and one persistent lesion of the sympathetic chain.

CONCLUSIONS

The authors describe the endoscopic technique of anterior spinal canal decompression in the thoracolumbar spine. The morbidities associated with an open procedure were avoided, and excellent spinal canal clearance was accomplished as was associated neurological improvement.

Is a single anterolateral screw-plate fixation sufficient for the treatment of spinal fractures in the thoracolumbar junction? A biomechanical in vitro investigation

Controversy exists about the indications, advantages and disadvantages of various surgical techniques used for anterior interbody fusion of spinal fractures in the thoracolumbar junction. The purpose of this study was to evaluate the stabilizing effect of an anterolateral and thoracoscopically implantable screw-plate system. Six human bisegmental spinal units (T12-L2) were used for the biomechanical in vitro testing procedure. Each specimen was tested in three different scenarios: (1) intact spinal segments vs (2) monosegmental (T12/L1) anterolateral fixation (macsTL, Aesculap, Germany) with an interbody bone strut graft from the iliac crest after both partial corpectomy (L1) and discectomy (T12/L1) vs (3) bisegmental anterolateral instrumentation after extended partial corpectomy (L1), and bisegmental discectomy (T12/L1 and L1/L2). Specimens were loaded with an alternating, nondestructive maximum bending moment of +/-7.5 Nm in six directions: flexion/extension, right and left lateral bending, and right and left axial rotation. Motion analysis was performed by a contact-less three-dimensional optical measuring system. Segmental stiffness of the three different scenarios was evaluated by the relative alteration of the intervertebral angles in the three main anatomical planes. With each stabilization technique, the specimens were more rigid, compared with the intact spine, for flexion/extension (sagittal plane) as well as in left and right lateral bending (frontal plane). In these planes the bisegmental instrumentation compared to the monosegmental case had an even larger stiffening effect on the specimens. In contrast to these findings, axial rotation showed a modest increase of motion after bisegmental instrumentation. To conclude, the immobilization of monosegmental fractures in the thoracolumbar junction can be secured by means of bone grafting and the implant used in this study for all three anatomical planes. After bisegmental anterolateral stabilization a sufficient reduction of the movements was registered for flexion/extension and lateral bending. However, the observed slight increase of the range of motion in the transversal plane may lead to loosening of the implant before union. Therefore, the use of an additional dorsal fixation device should be considered.

Influence of screw-cement enhancement on the stability of anterior thoracolumbar fracture stabilization with circumferential instability

The influence of additional dorsal structure damage on anterior stabilization of a thoracolumbar fracture is still unknown. Screw-cement enhancement can be used to reinforce the stability of anterior instrumentation. We have developed a new anchorage system for fixation of anterior stabilization devices, adapted through geometric optimization and the additional option of cementation after screw insertion. This study examines the question of whether this enhancement is strong enough to enable a single anterior procedure and still compensate for dorsal instability. Various spinal reconstruction procedures were evaluated biomechanically in an increasing ventrodorsal instability model for thoracolumbar fracture stabilization. A biomechanical in vitro study, simulating stabilized defect situations (corporectomy/vertebrectomy) with strut grafting and overbridging instrumentation, was performed on six human T10-L2 cadaveric specimens. The primary stability parameters, range of motion and neutral zone, were evaluated with or without anterior screw-cement enhancement. This was compared with a single conventional anterior stabilization without a dorsal defect (corporectomy). It was also compared with a single anterior, posterior or combined procedure in the presence of additional dorsal structure damage (vertebrectomy). The use of an additional cementable screw dowel enhanced the primary stability of the anterior instrumentation, compensating for dorsal instability. These results are warranted for the clinical use of minimally open or endoscopic techniques, creating the highest possible primary stability while performing a single anterior enhanced instrumentation with a tissue-preserving approach.

The endoscopically assisted simultaneous posteroanterior reconstruction of the thoracolumbar spine in prone position

BACKGROUND CONTEXT

The reconstruction of the anterior column of the thoracolumbar spine has become more common in the last few years, due largely to the unfavorable results of exclusively posterior surgical treatment, which has been associated with a lack of about 10 degrees of kyphosis correction after removal of the instrumentation. The minimally invasive anterior techniques have reduced the morbidity of the anterior approach significantly.

PURPOSE

A minimally invasive technique for anterior stabilization of the spine may reduce the morbidity of the open approach. Irrespective of an anterior open or an endoscopic approach, the posteroanterior instrumentation of thoracolumbar fractures requires time-consuming intraoperative maneuvers to change the patient position from prone to lateral. We describe here a standardized anterior endoscopically assisted approach for the segments T4 to L4. This approach allows the patient to remain in prone position. A 4- to 5-cm incision combined with a retractor system is used.

STUDY DESIGN/SETTING

In a prospective study, all patients of our clinic who underwent surgery of the thoracolumbar spine between July 1999 and May 2001 were registered. Study criteria were duration of surgery, duration of anesthesia, intra- and postoperative complications.

PATIENT SAMPLE

Between July 1999 and May 2001, 42 patients (25 male, 17 female, average age of 41.9 years), who presented with 55 injured spinal levels and underwent surgery of the thoracolumbar spine in prone position, were included.

OUTCOME MEASURES

Duration of surgery (posterior/anterior/total), duration of anesthesia, method of instrumentation, intra- and postoperative complications, postoperative hospital stay and radiographs were evaluated.

METHODS

Surgery was performed in prone position. A thoracic approach was used for instrumentation of T9 to L2. A retroperitoneal approach was used for stabilization of L1 to L5. Both procedures were endoscopically assisted with a new retractor system (Synframe; Synthes GmbH, Umkirch, Germany). In this manner, only an incision 4 to 5 cm long and a stab incision for the endoscope were required. The whole procedure was performed in prone position without a change of position during surgery.

RESULTS

A total of 42 patients underwent surgery following this technique: 14 isolated anterior procedures (median duration of surgery, 181 minutes); 13 simultaneous one-stage procedures (median duration of surgery: 210 minutes) and 15 combined two-stage procedures (median duration of surgery: 90 minutes posterior, 120 minutes anterior, 240 minutes posterior+anterior). In the simultaneous posteroanterior procedures, the anterior instrumentation was performed 20 times using one rod, twice using two rods and in six patients simply by bone grafting. No intraoperative complications were observed. In the postoperative course, one case of pneumothorax, one case of hemothorax and one case of transient intercostal neuralgia occurred.

CONCLUSION

The approach to the anterior spine in prone position is feasible by using a self-holding retractor system for the region between T4 and L4. The duration of anesthesia for the one-stage simultaneous procedure was reduced by about 40 minutes, because changing the position of the patient is no longer necessary. The minimal incision, in combination with the retractor system, significantly reduces cost by allowing the use of less expensive instruments and implants. The advantages of the open and the endoscopic techniques are combined, while their disadvantages are minimized. The main advantage of the prone position is the opportunity to access the anterior and posterior spine simultaneously, which is especially helpful in reduction maneuvers.

Solvent-preserved, bovine cancellous bone blocks used for reconstruction of thoracolumbar fractures in minimally invasive spinal surgery-first clinical results

We investigated the osseointegration of solvent-preserved, xenogenous cancellous bone blocks in the treatment of unstable fractures of the thoracolumbar junction. In 22 patients, the anterior repair procedure was performed by thoracoscopy or minimally invasive retroperitoneal surgery. Twenty-two patients had undergone monosegmental anterior fusion and were surveyed prospectively. Solvent-preserved, bovine cancellous bone blocks were used in 11 patients; iliac crest bone graft was used in the others. Follow-up after 12 months included CT scans, which revealed successful osseointegration in eight out of 11 patients who had received autogenous iliac crest bone grafts, while three patients showed a partial integration. There were no graft fragmentations. In patients who had received solvent-preserved, xenogenous cancellous bone blocks, complete osseointegration was achieved at the graft-bone interface in only two out of 11 cases, after 1 year. Partial integration was found in three patients. In view of these results, autogenous iliac crest bone grafts are still the unrivalled standard for defect repair in spinal surgery.

Minimally invasive ventral spondylodesis for thoracolumbar fracture treatment: surgical technique and first clinical outcome

A new instrumentation system for ventral stabilization of the spine that can be used for an endoscopic and minimally invasive approach was developed. We describe the implantation technique and report on the first clinical results. This prospective study covers the first 45 patients to undergo this new technique since it was introduced in 1999. In all patients the operation was successfully performed in a completely minimally invasive procedure. Mono- and bisegmental stabilization was performed mainly at the thoracolumbar junction after initial posterior instrumentation in most cases. Lesions varied from fresh/old fractures to metastases (T5-L3). Pre- and postoperative follow-up included clinical examination and radiological visualization via X-ray and computed tomographic scan. Our experience with this minimally invasive procedure demonstrated the feasibility of the method.