Clinical analysis of percutaneous facet screw fixation after anterior lumbar interbody fusion

Lumbar facet joint stabilization for symptomatic spinal degenerative disease: A systematic review of the literature

Objective

Lumbar spinal degenerative disease (LSDD), unresponsive to conservative therapy, is commonly treated by surgical decompression and interbody fusion. Since facet joint incompetence has been suggested as responsible for the entire phenomenon of spinal degeneration, facet stabilization can be considered as an alternative technique to treat symptomatic spinal degenerative disease. The purpose of this study was to systematically review the literature for studies utilizing lumbar facet joint fixation techniques for LSDD to assess their safety and efficacy.

Methods

A systematic literature review was performed following the preferred reporting items for systematic reviews and meta-analyses statement, with no limits in terms of date of publication. Demographic data, inclusion criteria, clinical and radiological outcome, frequency of adverse events (AEs), and follow-up time were evaluated.

Results

A total of 19 studies were included with a total of 1577 patients. The techniques used for facet arthrodesis were Goel intra-articular spacers in 21 patients (5.3%), Facet Wedge in 198 patients (15.8%), facet screws fixation techniques in 1062 patients (52.6%), and facet joints arthroplasty in 296 patients (26.3%). Clinical outcomes were assessed through the evaluation of pain relief and improvement in functional outcome. Radiological outcomes were assessed by the evaluation of proper positioning of instrumentation, solid bony fusion rate, and preservation of disk height. AE's mainly observed were pseudoarthrosis, reoperation, instrumentation displacement/malpositioning/migration, neurological impairment, deep vein thrombosis, and infections. The mean follow-up time ranged from 6 months to 11.7 years.

Conclusion

Our data demonstrate that facet joint arthrodesis appears to be effective in managing LSDD. These findings, however, are limited by the small sample size of patients. Accordingly, larger series are needed before formal recommendations can be made.

Transfacet screws using spinal navigation in addition to anterior or oblique lumbar interbody fusion: technical note and preliminary results

Transfacet screws (TFS) are an alternative to the classic bilateral pedicular screws (BPS) in addition to anterior (ALIF) or oblique (OLIF) lumbar interbody fusion. Spinal navigation could help the surgeon in technically demanding procedures in order to avoid screw malposition. Although spinal navigation is commonly used in BPS, its contribution in TFS remains unclear. Our aim here was to assess the feasibility of TFS using spinal navigation in addition to anterior lumbar fusion. Five patients suffering from lumbar degenerative disc disease were included. During the same general anaesthesia, we performed successively an ALIF or OLIF and then a TFS according to Boucher technique using spinal navigation (O-arm). No peri-operative complication occurred, and all the screws were successfully positioned (n = 10). All clinical scores (ODI, VAS L and VAS R) improved at 6-month follow-up. Segmental lordosis increased from 6° [2.4°-12°] to 13.6° [8°-17°]. Fusion was achieved for the five patients. TFS using O-arm in addition to ALIF/OLIF is feasible. To confirm our early favourable outcomes on clinical and radiological data, this technique must be evaluated on larger samples of patients.

Robot-assisted Percutaneous Transfacet Screw Fixation Supplementing Oblique Lateral Interbody Fusion Procedure: Accuracy and Safety Evaluation of This Novel Minimally Invasive Technique

Objectives

Percutaneous transfacet screw fixation (pTSF) is a minimally invasive posterior fixation technique supplementing oblique lateral interbody fusion (OLIF) for lumbar spinal disorders. Accurate screw insertion is difficult to achieve and technically demanding under 2‐D fluoroscopy. Recently developed robot‐assisted spinal surgery demonstrated a high level of accuracy of pedicle screw insertion and a low complication rate. No published study has reported this combination technique. The aim of our study was to evaluate the accuracy and safety properties of the combination of both minimally invasive techniques: robot‐assisted pTSF supplementing the OLIF procedure.

Methods

This was an experimental and prospective study. Selected consecutive patients with lumbar degenerative disorders received robot‐assisted pTSF supplementing the OLIF procedure using the TianJi Robot system operated by one senior surgeon from March to October 2018. The accuracy of screw insertion and perioperative screw‐related complications were evaluated. Assessment of the accuracy of screw insertion included intraoperative robotic guidance accuracy and incidence of screw encroachments. Intraoperative robotic guidance accuracy referred to translational and angular deviations of screws, which were assessed by comparing the planned and actual screw trajectories guided by the robot on reconstructed images using TianJi Robot Planning Software. Screw encroachments were evaluated on postoperative CT images and classified by a grading system (A, excellent; B, good; C, poor). Screw‐related complications including intraoperative pin skidding, screw malposition and adjustment, together with postoperative neurological symptoms that correlated with screw malposition were recorded.

Results

Ten patients, with an average age of 60.2 years, were selected and recruited in this study. All cases were degenerative lumbar spinal disorders, out of which there were 6 cases of Meyerding Grade I degenerative spondylolisthesis. Twenty‐four transfacet screws were inserted by robotic assistance. Instrumented levels included nine segments at L_4–5 level and three segments at L_3–4 level. Two patients had both L_4–5 and L_3–4 level fixation. The average surgical time was 3.3 h (SD, 0.8 h). The mean blood loss was 90 mL (SD, 32 mL). Intraoperative guidance accuracy showed 1.09 ± 0.17 mm (ranging from 0.75 to 1.22 mm) translational deviation and 2.17° ± 0.39° (ranging from 1.47° to 2.54°) angular deviation. The gradings of screw encroachment were: 17 screws (71%) with Grade A, 6 screws (25%) with Grade B, and 1 screw (4%) with Grade C. Only one pin skidding occurred intraoperatively and revised subsequently. No postoperative neurological complications were found.

Conclusion

Our preliminary study of robot‐assisted pTSF supplementing the OLIF procedure showed a high level of accuracy for screw insertion and this minimally invasive combination technique was found to be a feasible and safe procedure.

Percutaneous screw placement in the lumbar spine with a modified guidance technique based on 3D CT navigation system

Several guidance techniques have been employed to increase accuracy and reduce surgical time during percutaneous placement of pedicle screws (PS). The purpose of our study was to present a modified technique for percutaneous placement of lumbar PS that reduces surgical time. We reviewed 23 cases of percutaneous PS placement using our technique for minimally invasive lumbar surgeries and 24 control cases where lumbar PS placement was done via common technique using Jamshidi needles (Becton, Dickinson and Company, Franklin Lakes, NJ, USA). An integrated computer-guided navigation system was used in all cases. In the technique modification, a handheld drill with a navigated guide was used to create the path for inserting guidewires through the pedicles and into the vertebral bodies. After drill removal, placement of the guidewires through the pedicles took place. The PS were implanted over the guidewires, through the pedicles and into the vertebral bodies. Intraoperative computed tomography was performed after screw placement to ensure optimal positioning in all cases. There were no intraoperative complications with either technique. PS placement was correct in all cases. The average time for each PS placement was 6.9 minutes for the modified technique and 9.2 minutes for the common technique. There was no significant difference in blood loss. In conclusion, this modified technique is efficient and contributes to reduced operative time.

A Comparative Biomechanical Analysis of Stand Alone Versus Facet Screw and Pedicle Screw Augmented Lateral Interbody Arthrodesis: An In Vitro Human Cadaveric Model

STUDY DESIGN

Cadaveric biomechanical study.

OBJECTIVE

To investigate the kinematic response of a stand-alone lateral lumbar interbody cage compared with supplemental posterior fixation with either facet or pedicle screws after lateral discectomy.

SUMMARY OF BACKGROUND DATA

Lateral interbody fusion is a promising minimally invasive fixation technique for lumbar interbody arthrodesis. The biomechanical stability of stand-alone cage placement compared with supplemental posterior fixation with either facet or bilateral pedicle screws remains unclear.

METHODS

A 6-degree of freedom spine simulator was used to test flexibility in 7 human cadaveric specimens. Flexion-extension, lateral-bending, and axial-rotation were tested in the intact condition, followed by destabilization through a lateral discectomy at L2-L3 and L4-L5. Specimens were then reconstructed at both operative segments in the following sequence: (1) lateral interbody cage placement; (2) either Discovery facet screws or the Viper F2 system using a transfacet-pedicular trajectory randomized to L2-L3 or L4-L5; and (3) removal of facet screw fixation followed by placement of bilateral pedicle screw instrumentation. Acute range of motion (ROM) was quantified and analyzed.

RESULTS

All 4 reconstruction groups, including stand-alone interbody cage placement, bilateral Discovery facet screws, the Viper F2 system, and bilateral pedicle screw-rod stabilization, resulted in a significant decrease in acute ROM in all loading modes tested (P<0.05). There were no significant differences observed between the 4 instrumentation groups (P>0.05). Although not statistically significant, the Viper F2 system resulted in greatest reduction of acute ROM in both flexion-extension and axial rotation versus all other treatments (P>0.05).

CONCLUSIONS

Stand-alone interbody cage placement results in a significant reduction in acute ROM at the operative segment in the absence of posterior supplemental fixation. If added fixation is desired, facet screw placement, including the Viper F2 facet screw system using an integrated compression washer and transfacet-pedicular trajectory, provides similar acute stability to the spinal segment compared with traditional bilateral pedicle screw fixation in the setting of lateral interbody cage deployment.

Percutaneous Lumbar Transfacet Screw Fixation: A Technique Analysis of 176 Screws in 83 Patients With Assessment of Radiographic Accuracy, Hardware Failure, and Complications

Supplemental Digital Content Is Available in the Text.

A biomechanical comparison of 3 different posterior fixation techniques for 2-level lumbar spinal disorders

OBJECT

This study sought to make a biomechanical comparison of 3 different posterior fixation techniques for 2-level lumbar spinal disorders.

METHODS

Eight fresh-frozen human cadaver lumbar spines (4 from L-1 to L-5, 4 from L-1 to S-1) were tested by applying pure moments of ± 8 Nm. Each specimen was first tested intact, and then the left facetectomies of L3-4 and L4-5 were performed to establish an unstable condition without removal of discs. Three instrumentation systems were then tested randomly: unilateral pedicle screw (UPS), UPS with contralateral translaminar facet screw (UPSFS), and bilateral pedicle screw (BPS). The range of motion (ROM) and the neutral zone (NZ) of L3-5 were measured.

RESULTS

All fixation types could reduce the ROM of L3-5 significantly in flexion, extension, and lateral bending, compared with the intact state. In axial torsion, only BPS reduced the ROM significantly, compared with the intact state. The UPSFS technique provided intermediate stability, which was superior to the UPS in flexion-extension and lateral bending, and inferior to the BPS in lateral bending. Compared with the intact state, the NZs decreased significantly for UPS, UPSFS, and BPS in flexion-extension, while not significantly in lateral bending and axial torsion.

CONCLUSIONS

In this study, among the 3 fixation techniques, BPS offered the highest stability, UPSFS provided intermediate stability, and UPS was the least stable for 2-level lumbar spinal disorders. UPSFS appeared to be able to offer a less invasive choice than BPS in well-selected patients with 2-level lumbar spinal disorders.

Prospective evaluation of 1-year outcomes in single-level percutaneous lumbar transfacet screw fixation in the lateral decubitus position following lateral transpsoas interbody fusion

PURPOSE

Lateral transpsoas lumbar interbody fusion (LTIF) is an accepted treatment for degenerative lumbar disc disease. Bilateral percutaneous transfacet (TF) fixation is a promising option for stabilization following LTIF. Here, we describe our experience with this technique and assess the clinical outcomes and efficacy.

METHODS

Thirty-eight consecutive patients were identified who underwent LTIF followed by bilateral percutaneous transfacet fixation in the lateral position. Preoperative and 1-year postoperative VAS scores, and operative data were prospectively recorded. One-year outcomes were also assessed according to the MacNab criteria. Fusion was assessed at 1 year via computed tomography and dynamic radiography. Two-tailed Student's t test was used to compare VAS scores.

RESULTS

Twenty-six patients underwent fusion at L4-5, 11 at L3-4, and one at L2-3; two patients were lost to follow-up. Mean operative time was 148.0 ± 47.9 min; mean blood loss was 33.0 ± 26.1 ml; mean hospital stay was 53.5 ± 51.2 h. Mean preoperative VAS scores for back and leg pain were 7.4 ± 3.0 and 7.0 ± 2.9, respectively; mean postoperative VAS scores for back and leg pain were 1.9 ± 2.4 (p < 0.0001) and 2.0 ± 3.0 (p < 0.0001), respectively. Most (89 %) patients had some relief, 72 % good to excellent and 17 % fair outcomes; eleven percent had little to no relief. There was one postoperative complication (pulmonary embolus). All patients had evidence of solid bony fusion.

CONCLUSIONS

Percutaneous transfacet fixation in the lateral position is a safe and effective alternative for fixation after LTIF and may be associated with shorter operative time and less blood loss than other posterior fixation techniques.

Outcomes of posterior facet versus pedicle screw fixation of circumferential fusion: a cohort study

PURPOSE

To compare single-level circumferential spinal fusion using pedicle (n = 27) versus low-profile minimally invasive facet screw (n = 35) posterior instrumentation.

METHOD

A prospective two-arm cohort study with 5-year outcomes as follow-up was conducted. Assessment included back and leg pain, pain drawing, Oswestry disability index (ODI), pain medication usage, self-assessment of procedure success, and >1-year postoperative lumbar magnetic resonance imaging.

RESULTS

Significantly less operative time, estimated blood loss and costs were incurred for the facet group. Clinical improvement was significant for both groups (p < 0.01 for all outcomes scales). Outcomes were significantly better for back pain and ODI for the facet relative to the pedicle group at follow-up periods >1 year (p < 0.05). Postoperative magnetic resonance imaging found that 20 % had progressive adjacent disc degeneration, and posterior muscle changes tended to be greater for the pedicle screw group.

CONCLUSION

One-level circumferential spinal fusion using facet screws proved superior to pedicle screw instrumentation.

Microscopic anterior foraminal decompression combined with anterior lumbar interbody fusion

BACKGROUND CONTEXT

Anterior lumbar interbody fusion (ALIF) with percutaneous pedicle screw fixation (PPF) provides successful surgical outcomes to isthmic spondylolisthesis patients with indirect decompression through foraminal volume expansion. However, indirect decompression through ALIF followed by PPF may not obtain a successful surgical outcome in patients with isthmic spondylolisthesis accompanied by foraminal stenosis caused by a posterior osteophyte or foraminal sequestrated disc herniation. Thus far, there has been no report of foraminal decompression through anterior direct access in the lumbar spine.

PURPOSE

This study aims to describe the new surgical technique of microscopic anterior foraminal decompression and to analyze the clinical outcomes and radiologic results of the microscopic anterior decompression during ALIF followed by PPF.

STUDY DESIGN/SETTING

We conducted a multisurgeon, retrospective, clinical series from a single institution.

PATIENT SAMPLE

This study was carried out from March 2007 to July 2010 and included 40 consecutive patients with isthmic spondylolisthesis accompanied by foraminal stenosis caused by posterior osteophyte or foraminal sequestrated disc herniation undergoing microscopic anterior foraminal decompression during ALIF followed by PPF.

OUTCOME MEASURES

The visual analog scales (VAS) of back and leg pain and the Oswestry disability index were measured preoperatively and at the last follow-up.

METHODS

Postoperative computed tomography and magnetic resonance imaging measured whether decompression of neural structure had been made and morphometric change of the foramen and the amount of resected bone. Moreover, segmental lordosis, whole lumbar lordosis, disc height, and degree of listhesis were measured through X-ray examination before the operation and at the last follow-up; we also verified whether fusion had been achieved.

RESULTS

Successful decompression was confirmed in both patients with foraminal stenosis caused by posterior osteophyte and those with foraminal sequestrated disc herniation. Clinically, compared with before the surgery, the VAS (leg and back) and the Oswestry disability index significantly decreased at the last follow-up (p=.000). With regard to radiology, at the last follow-up all patients had bone fusion on X-ray examination, and an increase in disc height, a reduction in the degree of listhesis, an increase in segmental lordosis, and an increase in whole lumbar lordosis were significant in both groups (p=.000) compared with before the surgery. Foraminal volume, foraminal width, and foraminal height also significantly increased postoperatively compared with before the operation (p=.000). The height, width, and dimension of resected body were 4.61±1.05 mm, 7.92±1.42 mm, 17.15±4.96 mm(2), respectively, in patients with foraminal stenosis caused by a posterior osteophyte, and 3.88±0.92 mm, 6.8±1.29 mm, and 13.12±2.25 mm(2), respectively, in patients with foraminal sequestrated disc.

CONCLUSIONS

The microscopic anterior foraminal approach provides successful foraminal decompression. Combined with ALIF and PPF, this approach shows a good surgical outcome in patients with isthmic spondylolisthesis accompanied by foraminal stenosis caused by a posterior osteophyte or those with foraminal sequestrated disc herniation.

Managing design excellence tools during the development of new orthopaedic implants

Design excellence (DEX) tools have been widely used for years in some industries for their potential to facilitate new product development. The medical sector, targeted by cost pressures, has therefore started adopting them. Numerous tools are available; however only appropriate deployment during the new product development stages can optimize the overall process. The primary study objectives were to describe generic tools and illustrate their implementation and management during the development of new orthopaedic implants, and compile a reference package. Secondary objectives were to present the DEX tool investment costs and savings, since the method can require significant resources for which companies must carefully plan. The publicly available DEX method "Define Measure Analyze Design Verify Validate" was adopted and implemented during the development of a new spinal implant. Several tools proved most successful at developing the correct product, addressing clinical needs, and increasing market penetration potential, while reducing design iterations and manufacturing validations. Cost analysis and Pugh Matrix coupled with multi generation planning enabled developing a strong rationale to activate the project, set the vision and goals. improved risk management and product map established a robust technical verification-validation program. Design of experiments and process quantification facilitated design for manufacturing of critical features, as early as the concept phase. Biomechanical testing with analysis of variance provided a validation model with a recognized statistical performance baseline. Within those tools, only certain ones required minimum resources (i.e., business case, multi generational plan, project value proposition, Pugh Matrix, critical To quality process validation techniques), while others required significant investments (i.e., voice of customer, product usage map, improved risk management, design of experiments, biomechanical testing techniques). All used techniques provided savings exceeding investment costs. Some other tools were considered and found less relevant. A matrix summarized the investment costs and generated estimated savings. Globally, all companies can benefit from using DEX by smartly selecting and estimating those tools with best return on investment at the start of the project. For this, a good understanding of the available company resources, background and development strategy are needed. In conclusion, it was possible to illustrate that appropriate management of design excellence tools can greatly facilitate the development of new orthopaedic implant systems.

Biomechanical evaluation of stand-alone lumbar polyether-ether-ketone interbody cage with integrated screws

BACKGROUND CONTEXT

Stand-alone interbody cages with integrated screws potentially provide a biomechanically stable solution for anterior lumbar interbody fusion (ALIF) that alleviates the need for additional exposure for supplemental fixation, thereby reducing the chance of additional complications and morbidity.

PURPOSE

To compare the stability of a stand-alone anterior interbody fusion system with integrated fixation screws against traditional supplemental fixation methods and to evaluate the difference between three and four fixation screws in the stand-alone cage.

STUDY DESIGN

In vitro cadaveric biomechanical study.

METHODS

Eight cadaveric lumbar spines (L2-sacrum) were tested using a flexibility protocol consisting of three cycles to ±7.5 Nm in flexion-extension, lateral bending, and axial rotation. The conditions evaluated were intact spine; polyether-ether-ketone cage (zero integrated screws) at L4-L5; cage (zero screws)+bilateral pedicle screws (PS); cage (three screws); cage (four screws); cage (zero screws)+anterior plate; and cage (three screws)+spinous process plate. Motion at the index level was assessed using an optoelectronic system.

RESULTS

The cage without integrated screws reduced the motion in flexion-extension and lateral bending (p<.001) compared with that in the intact spine. In axial rotation, mean range of motion (ROM) was 8% greater than in intact spine (p>.962). The addition of three integrated screws reduced ROM significantly compared with the cage without screws in all motion planes (p<.001). A fourth screw had no statistically significant effect on the ROM, although there was a trend toward less motion with four screws compared with three. In flexion-extension, the cage with three integrated screws and the spinous process plate was the most rigid condition. There was no significant difference from the bilateral PS (p=.537); however, this was more rigid than all other conditions (p<.024). The most stable condition in lateral bending and axial rotation was the cage with bilateral PS. In lateral bending, the cage (three or four screws) was not significantly different from the cage with anterior plate or the cage (three screws) with spinous process plate fixation; however, only the latter condition was statistically comparable with bilateral PS. In axial rotation, there were no significant differences between the conditions that included integrated screws or supplemental fixation (p>.081).

CONCLUSIONS

Biomechanical testing revealed that the stand-alone cage with integrated screws provides more immediate stability than a cage alone and provides equivalent stability to ALIF constructs with supplemental fixation in lateral bending and axial rotation. Additional flexion-extension rigidity of the anterior cage maybe realized by the addition of a spinous process plate that was found to be as stable as supplemental bilateral PS.

Anterior interbody arthrodesis with percutaneous posterior pedicle fixation for degenerative conditions of the lumbar spine

This is a retrospective case series to evaluate clinical variables, complications and outcome of 50 patients who underwent anterior lumbar interbody fusion (ALIF) supplemented with posterior percutaneous pedicle screw fixation for degenerative conditions of the lumbar spine. Twenty-four patients underwent single-level fusion and 26 patients had a two-level fusion for a total of 76 levels fused. The mean lengths of the anterior and posterior (including repositioning) portions of the procedure were 131 and 102 min, respectively. The mean estimated blood loss for the entire procedure was 288 ml. The overall adverse event rate was 12%. The mean VAS score for leg pain, VAS score for back pain and mean ODI all improved postoperatively. This study found that ALIF using allograft bone and rhBMP-2 combined with percutaneous pedicle screw fixation had a high fusion rate and a low incidence of perioperative complications. Patient outcomes showed significant improvements in back and leg pain and physical functioning.

[Submuscular approach to the lumbar spine and extraforaminal cage implantation]

The posterior median approach to the lumbar spine may cause significant injury to the erector spinae muscles (ESM) which is minimized using the paralateral approach suggested by Ray. We have adopted this approach and have extended it into the disc space to allow cage implantation from outside the foramen (EPLIF - extraforaminal posterior lumbar interbody fusion). The initial exposure of the posterior vertebral elements between the ESM and the deep lumbar fascia is sufficient to attain the entry points of pedicle screws. The intervertebral foramen and posterior annulus fibrosus are then exposed after which distant lateral disc herniations may be removed, the foramen/lateral recess may be decompressed or an EPLIF performed following clearing and vertical distraction of the disc space. This is followed by ipsilateral transpedicular fixation (TpF), contralateral fixation (second approach) by TpF or translaminar screws. Indications are given for foraminal and extraforaminal disc herniation, stenosis of the foramen and/or of the lateral recess, posterolateral fusion, TpF and EPLIF. The submuscular approach and EPLIF have proven to be valuable alternatives to standard techniques.

Tubular microsurgery for lumbar discectomies and laminectomies in obese patients: operative results and outcome

STUDY DESIGN

This is a retrospective single-center case study involving 115 obese and nonobese patients who underwent minimally invasive lumbar surgery between 2004 and 2007.

OBJECTIVE

The purpose of this study was to evaluate the effect of minimally invasive spinal surgery in obese and nonobese patients by operative results and patient outcomes.

SUMMARY OF BACKGROUND DATA

Spinal surgery in obese patients is associated with increased complications, blood loss, and operative times. The potential benefits of minimally invasive lumbar surgery in obese patients are discussed.

METHODS

All patients underwent 1-level lumbar microdiscectomy or laminectomy using tubular retractors. Data were collected on patient demographics, comorbidities, smoking habits, operative results, and clinical outcomes, and compared for obese and nonobese patients. Operative results included operative times, blood loss, length of stay, and perioperative complications. Clinical outcomes were assessed by using pre- and postoperative visual analog scale and Macnab outcome criteria at most recent follow-up.

RESULTS

In this study, 31% of 115 patients were classified as obese. Obese patients tended to undergo surgery at a younger age. Obesity, comorbidities, and age did not have an impact on patient outcome at a mean follow-up of 15.9 months. No significant differences were seen between obese versus nonobese patients in terms of incision lengths, operative time, blood loss, and complication rates. In obese patients, all parameters and operative results compared favorably to reported historical results of patients undergoing open lumbar surgery. Overall, favorable outcome was seen in 92% and 84% of obese and nonobese lumbar microdiscectomy patients, respectively, and in 75% of laminectomy patients. Postoperative visual analog scale did not show any significant difference.

CONCLUSION

This is the first study comparing operative results from tubular microsurgery between obese and nonobese patients. No major differences were detected in outcome, operative and perioperative data including complication rates. With tubular microsurgery, obese patients experienced the same or equally beneficial outcome, compared to nonobese patients, while incision lengths, blood loss, operative times, and length of stay were less when compared to open procedures. Other comorbidities and age had no significant impact on perioperative complications and clinical outcome.

Percutaneous instrumentation of the thoracic and lumbar spine

The development of percutaneous instrumentation systems has been a significant milestone in the ability of surgeons to perform complex spinal procedures through minimally invasive approaches. These systems rely on cannulated screws or portal systems and using intraoperative imaging to allow accurate placement of the spinal implants without a full traditional exposure of the spine. This article reviews the operative concepts and techniques used to place percutaneous instrumentation in the thoracolumbar spine.

Minimally Invasive Transmuscular Pedicle Screw Fixation of the Thoracic and Lumbar Spine

OBJECTIVE:

This study assessed the feasibility and safety of percutaneous posterior pedicle screw fixation for instabilities of the thoracic and lumbar spine, using standard instruments designed for the open approach and fluoroscopy.

METHODS:

All patients who underwent percutaneous posterior pedicle screw fixation of the thoracic and lumbar spine were studied retrospectively. Charts and operative notes were analyzed for epidemiological data, underlying spinal pathological features, and indications for stabilization, stabilized segments, number of implanted pedicle screws, surgical time, and complications. Postoperative computed tomographic scans were analyzed for screw position.

RESULTS:

From May 2002 through May 2005, 115 internal fixators were implanted percutaneously in 104 patients. A total of 488 pedicle screws were implanted, stabilizing 1 to 5 spinal motion segments. Median surgical time was 93 minutes. On postoperative computed tomographic scans, 87% of screw positions were rated good, 10% were rated acceptable, and 3% were rated unacceptable. A total of 11 revisions were necessary, 9 for misplaced screws and 2 for loosening of anchor bolts. Only two of the patients experienced new clinical symptoms (i.e., radicular pain) because of screw misplacement. No patients experienced new neurological deficits or other surgery-related morbidity. @@@@CONCLUSION:@@ This study shows that percutaneous internal pedicle screw fixation using standard instruments is feasible and safe for posterior stabilization of the thoracic and lumbar spine. It is a straightforward alternative for open approaches or minimally invasive ones using navigation in conjunction with customized instruments. Accuracy of screw placement is similar to that reported for other techniques.

Minimally Invasive Fusion and Fixation Techniques

Instrumented fusion plays an important role in treating a variety of degenerative and traumatic diseases of the spine. Traditional open techniques have been associated with a high degree of approach-related morbidity because of muscle retraction and blood loss. A variety of minimally invasive techniques have been developed for instrumentation of the entire spine. Advances in our understanding of the cellular and molecular mechanisms for stable bony fusion should promote the use of even less invasive techniques in the future.