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1.  Mid-term clinical results of minimally invasive decompression and posterolateral fusion with percutaneous pedicle screws versus conventional approach for degenerative spondylolisthesis with spinal stenosis 
European Spine Journal  2011;21(6):1171-1177.
In order to minimize perioperative invasiveness and improve the patients’ functional capacity of daily living, we have performed minimally invasive lumbar decompression and posterolateral fusion (MIS-PLF) with percutaneous pedicle screw fixation for degenerative spondylolisthesis with spinal stenosis. Although several minimally invasive fusion procedures have been reported, no study has yet demonstrated the efficacy of MIS-PLF in degenerative spondylolisthesis of the lumbar spine. This study prospectively compared the mid-term clinical outcome of MIS-PLF with those of conventional PLF (open-PLF) focusing on perioperative invasiveness and patients’ functional capacity of daily living.
Materials and methods
A total of 80 patients received single-level PLF for lumbar degenerative spondylolisthesis with spinal stenosis. There were 43 cases of MIS-PLF and 37 cases of open-PLF. The surgical technique of MIS-PLF included making a main incision (4 cm), and neural decompression followed by percutaneous pedicle screwing and rod insertion. The posterolateral gutter including the medial transverse process was decorticated and iliac bone graft was performed. The parameters analyzed up to a 2-year period included the operation time, intra and postoperative blood loss, Oswestry-Disability Index (ODI), Roland-Morris Questionnaire (RMQ), the Japanese Orthopaedic Association score, and the visual analogue scale of low back pain. The fusion rate and complications were also reviewed.
The average operation time was statistically equivalent between the two groups. The intraoperative blood loss was significantly less in the MIS-PLF group (181 ml) when compared to the open-PLF group (453 ml). The postoperative bleeding on day 1 was also less in the MIS-PLF group (210 ml) when compared to the open-PLF group (406 ml). The ODI and RMQ scores rapidly decreased during the initial postoperative 2 weeks in the MIS-PLF group, and consistently maintained lower values than those in the open-PLF group at 3, 6, 12, and 24 months postoperatively. The fusion rate was statistically equivalent between the two groups (98 vs. 100%), and no major complications occurred.
The MIS-PLF utilizing a percutaneous pedicle screw system is less invasive compared to conventional open-PLF. The reduction in postoperative pain led to an increase in activity of daily living (ADL), demonstrating rapid improvement of several functional parameters. This superiority in the MIS-PLF group was maintained until 2 years postoperatively, suggesting that less invasive PLF offers better mid-term results in terms of reducing low back pain and improving patients’ functional capacity of daily living. The MIS-PLF utilizing percutaneous pedicle screw fixation serves as an alternative technique, eliminating the need for conventional open approach.
PMCID: PMC3366131  PMID: 22173610
Minimally invasive spine surgery; Posterolateral fusion; Percutaneous pedicle screw; Degenerative spondylolisthesis; Lumbar spine
2.  Long-term results of pediculo-body fixation and posterolateral fusion for lumbar spondylolisthesis 
European Spine Journal  2009;18(Suppl 1):151-155.
Grob et al. (Eur Spine J 5:281–285, 1996) illustrated a new fixation technique in inveterate cases of grade 2–3 spondylolisthesis (degenerative or spondylolytic): a fusion without reduction of the spondylolisthesis. Fixation of the segment was achieved by two cancellous bone screws inserted bilaterally through the pedicles of the lower vertebra into the body of the upper slipped vertebra. Since 1998 we have been using this technique according to the authors’ indications: symptomatic spondylolisthesis with at least 25% anterior slippage and advanced disc degeneration. Afterwards this technique was used also in spondylolisthesis with low reduction of the disc height and slippage less than 25%. In every case we performed postero-lateral fusion and fixation with two AO 6.5 Ø thread 16 mm cancellous screws. From 1998 to 2002 we performed 62 fusions for spondylolisthesis with this technique: 28 males (45.16%) and 34 females (54.84%), mean age 45 years (14–72 years). The slipped vertebra was L5 in 57 cases (92%), L4 in 2 cases (3.2%), L3 in 1 case (1.6%), combined L4 and L5 in 2 cases (3.2%). In all cases there was an ontogenetic spondylolisthesis with lysis. Lumbar pain was present in 22 patients and lumbar-radicular pain was present in 40 patients. The mean preoperative VAS was 6.2 (range 5–8) for lumbar pain, and 5.5 (range 4–7) for leg pain. The fusion area was L5–S1 in 53 cases (85.5%), L3–L4 in 1 case (1.6%), L4–S1 in 8 cases (12.9%). A decompression of the spinal canal by laminectomy was performed in 33 procedures (53%). When possible a bone graft was done from the removed neural arc, and from the posterior iliac crest in the other cases. The mean blood loss was about 254 ml (100–1,000). The mean operative time was 75 min (range 60–90). The results obtained by computerized analysis at follow-up at least 5 years after surgery showed a significant improvement in preoperative symptoms. The patients were asymptomatic in 52 cases (83.9%); strained-back pain was present in 8 cases (12.9%), and there was persistent lumbar-radicular pain in 2 cases (3.2%). The mean ODI score was 2.6%, the mean VAS back pain was 1.3, the mean VAS leg pain 0.7. Some complications were observed: a nerve root compression by a screw invasion of intervertebral foramen, resolved by screw removal; an iliac artery compression by a lateral exit screw from pediculo, resolved by screw removal; a deep iliac vein phlebitis with thrombosis caused by external compression due to a wrong intraoperative position, treated by medicine. Two cases of synthesis mobilization and two cases of broken screws was detected. No cases of pseudoarthrosis and immediate or late superficial or deep infection were observed. The analysis of the long-term results of the spondylolisthesis surgical treatment with direct pediculo-body screw fixation and postero-lateral fusion gave a very satisfactory response. The technique is reliable in allowing an optimal primary stability, creating the best biomechanical conditions to obtain a solid fusion.
PMCID: PMC2899605  PMID: 19444490
Spondylolisthesis; Spinal fusion; Back pain; Radicular pain
3.  Spinous process-splitting open pedicle screw fusion provides favorable results in patients with low back discomfort and pain compared to conventional open pedicle screw fixation over 1 year after surgery 
European Spine Journal  2012;21(4):745-753.
The conventional open pedicle screw fusion (PSF) requires an extensive detachment of the paraspinal muscle from the posterior aspect of the lumbar spine, which can cause muscle injury and subsequently lead to “approach-related morbidity”. The spinous process-splitting (SPS) approach for decompression, unilateral laminotomy for bilateral decompression, and the Wiltse approach for pedicle screw insertion are considered to be less invasive to the paraspinal musculature. We investigated whether SPS open PSF combined with the abovementioned techniques attenuates the paraspinal muscle damage and yields favorable clinical results, including alleviation in the low back discomfort, in comparison to the conventional open PSF.
We studied 53 patients who underwent single-level PSF for the treatment of degenerative spondylolisthesis (27 patients underwent SPS open PSF and the other 26 underwent the conventional open PSF). The clinical outcomes were assessed using the Japanese Orthopedic Association (JOA) score, the Roland–Morris disability questionnaire (RDQ), and the visual analog scale (VAS) for low back pain and low back discomfort (heavy feeling or stiffness). Postoperative multifidus (MF) atrophy was evaluated using MRI. Follow-up examinations were performed at 1 and 3 years after the surgery.
Although there was no significant difference in the JOA and RDQ score between the two groups, the VAS score for low back pain and discomfort after the surgery were significantly lower in the SPS open PSF group than in the conventional open PSF group. The extent of MF atrophy after SPS open PSF was reduced more significantly than after the conventional open PSF during the follow-up. The MF atrophy ratio was found to correlate with low back discomfort at the 1-year follow-up examination.
In conclusion, SPS open PSF was less damaging to the paraspinal muscle than the conventional open PSF and had a significant clinical effect, reducing low back discomfort over 1 year after the surgery.
PMCID: PMC3326135  PMID: 22237851
Posterior lumbar fusion; Multifidus muscle; Wiltse approach; Minimally invasive; Conventionally open
4.  Endoscopic transforaminal decompression, interbody fusion, and percutaneous pedicle screw implantation of the lumbar spine: A case series report 
On the basis of the experiences gained from conventional open spinal procedures, a long list of desirable objectives have emerged with the evolution of the lesser invasive spinal procedures. At the top of that list is the desire to minimize the trauma of surgery. The rest of the objectives, which include reductions of operating time, surgical blood loss, hospital stay, postoperative narcotic medication, convalescence, complication rates, and escalating health care costs, as well as the desire of elderly patients to continue rigorous physical activities, largely depend on the ability to minimize the trauma of surgery. The purpose of this study was to investigate the feasibility of the least invasive lumbar decompression, interbody fusion and percutaneous pedicle screw implantation, to minimize surgical trauma without compromising the quality of the treatment outcome, as well as to minimize risk of complications.
In this case series, 60 patients with diagnoses of degenerative disc disease, degenerative motion segments with stenosis, and spondylolisthesis, in whom nonoperative treatments failed, were treated with endoscopic transforaminal decompression and interbody fusion by 1 surgeon in 2 centers. The outcome measures were as follows: operating time, intraoperative blood loss, hospital stay, Visual Analogue Scale (VAS) scores for back and leg pain, scores on the Roland-Morris Disability Questionnaire, and postoperative imaging studies. A consecutive series of patients who met the treatment criteria completed VAS forms and Roland-Morris questionnaires preoperatively. Surgical procedures included arthroscopic decompression of the foramina and the discs; endplate preparation and implantation of allograft bone chips and bone morphogenetic protein 2 on absorbable collagen sponge into the disc space; and percutaneous implantation of pedicle screws. Postoperatively, the patients again completed the VAS forms and Roland-Morris questionnaires. Their charts were reviewed for office notes, operative notes, hospital stay, medications, and imaging studies. The latest X-ray and computed tomography scan films were reviewed and analyzed. Patients were followed up for a minimum of 6 months. The literature was reviewed for comparison of outcomes.
Sixty patients met the inclusion criteria. The mean age was 52.8 years. The duration of illness averaged 5 years. Follow-up ranged from 6 to 25 months, with a mean of 12 months. Preoperative diagnoses included degenerative disc disease, degenerative motion segments with stenosis, and spondylolisthesis. The mean time in the operating room was 2 hours 54 minutes. Estimated blood loss averaged 57.6 mL. The duration of the hospital stay averaged 2.6 days. Preoperative back pain and leg pain were significantly reduced (P < .005). Forty-seven imaging studies obtained at the last visit, including X-ray and computed tomography scans, showed solid fusion in 28 patients (59.6%), stable fixation in 17 (36.2%), and osteolysis around the pedicle screws in 2 (4.2%). All patients had improvement of motor function, whereas 2 patients complained of residual numbness. In addition, 8 patients (13%) complained of residual discomfort on extension of the lumbar spine. Two patients had pedicle screw–related complications requiring surgery. A review of the literature showed that endoscopic transforaminal decompression and interbody fusion performed better than open transforaminal lumbar interbody fusion/posterior lumbar interbody fusion, minimally invasive transforaminal lumbar interbody fusion, and extreme lateral lumbar interbody fusion, with regard to most parameters studied.
The endoscopic transforaminal lumbar decompression, interbody fusion, and percutaneous pedicle screw instrumentation consistently produced satisfactory results in all demographics. It performed better than the alternative procedures for most parameters studied.
PMCID: PMC4300894
ETDIF; Arthroscopic; Posterolateral; Interbody; Percutaneous; BMP-2
5.  Comparison of two-stage open versus percutaneous pedicle screw fixation in treating pyogenic spondylodiscitis 
Percutaneous pedicle screw instrumentation is a minimally invasive surgical technique; however, the effects of using percutaneous pedicle screw fixation in treating patients with spinal infections have not yet been well demonstrated. The aim of this study, therefore, was to determine whether percutaneous posterior pedicle screw instrumentation is superior to the traditional open approach in treating pyogenic spondylodiscitis.
We retrospectively reviewed data for 45 patients treated for pyogenic spondylodiscitis with anterior debridement and interbody fusion followed by a second-stage procedure involving either traditional open posterior pedicle screw fixation or percutaneous posterior pedicle screw fixation. Twenty patients underwent percutaneous fixation and 25 patients underwent open fixation. Demographic, operative, and perioperative data were collected and analyzed.
The average operative time for the percutaneous procedure was 102.5 minutes, while the average time for the open procedure was 129 minutes. The average blood loss for the percutaneous patients was 89 ml versus a 344.8 ml average for the patients in the open group. Patients who underwent the minimally invasive surgery had lower visual analogue scale scores and required significantly less analgesia afterwards. After two years of follow-up, neither recurrent infection nor intraoperative complications, such as wound infection or screw loosening, were found in the percutaneous group. Moreover, there was no significant difference in outcome between the two groups in terms of Oswestry Disability Index scores.
Anterior debridement and interbody fusion with bone grafting followed by minimally invasive percutaneous posterior instrumentation is an alternative treatment for pyogenic spondylodiscitis which can result in less intraoperative blood loss, shorter operative time, and reduced postoperative pain with no adverse effect on infection control.
PMCID: PMC4300775  PMID: 25519761
Minimally invasive surgery; Percutaneous pedicle screw; Pyogenic spondylodiscitis; Anterior interbody fusion
6.  Minimally Invasive Multi-Level Posterior Lumbar Interbody Fusion Using a Percutaneously Inserted Spinal Fixation System : Technical Tips, Surgical Outcomes 
There are technical limitations of multi-level posterior pedicle screw fixation performed by the percutaneous technique. The purpose of this study was to describe the surgical technique and outcome of minimally invasive multi-level posterior lumbar interbody fusion (PLIF) and to determine its efficacy.
Forty-two patients who underwent mini-open PLIF using the percutaneous screw fixation system were studied. The mean age of the patients was 59.1 (range, 23 to 78 years). Two levels were involved in 32 cases and three levels in 10 cases. The clinical outcome was assessed using the visual analog scale (VAS) and Low Back Outcome Score (LBOS). Achievement of radiological fusion, intra-operative blood loss, the midline surgical scar and procedure related complications were also analyzed.
The mean follow-up period was 25.3 months. The mean LBOS prior to surgery was 34.5, which was improved to 49.1 at the final follow up. The mean pain score (VAS) prior to surgery was 7.5 and it was decreased to 2.9 at the last follow up. The mean estimated blood loss was 238 mL (140-350) for the two level procedures and 387 mL (278-458) for three levels. The midline surgical scar was 6.27 cm for two levels and 8.25 cm for three level procedures. Complications included two cases of asymptomatic medial penetration of the pedicle border. However, there were no signs of neurological deterioration or fusion failure.
Multi-level, minimally invasive PLIF can be performed effectively using the percutaneous transpedicular screw fixation system. It can be an alternative to the traditional open procedures.
PMCID: PMC3259464  PMID: 22259691
Posterior lumbar interbody fusion; Percutaneous; Minimally invasive surgery
7.  Posterior Interspinous Fusion Device for One-Level Fusion in Degenerative Lumbar Spine Disease : Comparison with Pedicle Screw Fixation - Preliminary Report of at Least One Year Follow Up 
Transpedicular screw fixation has some disadvantages such as postoperative back pain through wide muscle dissection, long operative time, and cephalad adjacent segmental degeneration (ASD). The purposes of this study are investigation and comparison of radiological and clinical results between interspinous fusion device (IFD) and pedicle screw.
From Jan. 2008 to Aug. 2009, 40 patients underwent spinal fusion with IFD combined with posterior lumbar interbody fusion (PLIF). In same study period, 36 patients underwent spinal fusion with pedicle screw fixation as control group. Dynamic lateral radiographs, visual analogue scale (VAS), and Korean version of the Oswestry disability index (K-ODI) scores were evaluated in both groups.
The lumbar spine diseases in the IFD group were as followings; spinal stenosis in 26, degenerative spondylolisthesis in 12, and intervertebral disc herniation in 2. The mean follow up period was 14.24 months (range; 12 to 22 months) in the IFD group and 18.3 months (range; 12 to 28 months) in pedicle screw group. The mean VAS scores was preoperatively 7.16±2.1 and 8.03±2.3 in the IFD and pedicle screw groups, respectively, and improved postoperatively to 1.3±2.9 and 1.2±3.2 in 1-year follow ups (p<0.05). The K-ODI was decreased significantly in an equal amount in both groups one year postoperatively (p<0.05). The statistics revealed a higher incidence of ASD in pedicle screw group than the IFD group (p=0.029).
Posterior IFD has several advantages over the pedicle screw fixation in terms of skin incision, muscle dissection and short operative time and less intraoperative estimated blood loss. The IFD with PLIF may be a favorable technique to replace the pedicle screw fixation in selective case.
PMCID: PMC3488645  PMID: 23133725
Degenerative; Fusion device; Interspinous; Lumbar disease; Posterior; Adjacent segmental degeneration
8.  Percutaneous pedicle screw reduction and axial presacral lumbar interbody fusion for treatment of lumbosacral spondylolisthesis: A case series 
Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and is associated with significant complications. The advent of minimally invasive surgical techniques offers patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion offers an alternative procedure for the surgical management of low-grade lumbosacral spondylolisthesis.
Case presentation
Three patients who had L5-S1 grade 2 spondylolisthesis and who presented with axial pain and lumbar radiculopathy were treated with a minimally invasive surgical technique. The patients-a 51-year-old woman and two men (ages 46 and 50)-were Caucasian. Under fluoroscopic guidance, spondylolisthesis was reduced with a percutaneous pedicle screw system, resulting in interspace distraction. Then, an axial presacral approach with the AxiaLIF System (TranS1, Inc., Wilmington, NC, USA) was used to perform the discectomy and anterior fixation. Once the axial rod was engaged in the L5 vertebral body, further distraction of the spinal interspace was made possible by partially loosening the pedicle screw caps, advancing the AxiaLIF rod to its final position in the vertebrae, and retightening the screw caps. The operative time ranged from 173 to 323 minutes, and blood loss was minimal (50 mL). Indirect foraminal decompression and adequate fixation were achieved in all cases. All patients were ambulatory after surgery and reported relief from pain and resolution of radicular symptoms. No perioperative complications were reported, and patients were discharged in two to three days. Fusion was demonstrated radiographically in all patients at one-year follow-up.
Percutaneous pedicle screw reduction combined with axial presacral lumbar interbody fusion offers a promising and minimally invasive alternative for the management of lumbosacral spondylolisthesis.
PMCID: PMC3179763  PMID: 21910878
9.  Postoperative Changes in Paraspinal Muscle Volume: Comparison between Paramedian Interfascial and Midline Approaches for Lumbar Fusion 
Journal of Korean Medical Science  2007;22(4):646-651.
In this study, we compared the paramedian interfascial approach (PIA) and the traditional midline approach (MA) for lumbar fusion to determine which approach resulted in the least amount of postoperative back muscle atrophy. We performed unilateral transforaminal posterior lumbar interbody fusion via MA on the symptomatic side and pedicle screw fixation via PIA on the other side in the same patient. We evaluated the damage to the paraspinal muscle after MA and PIA by measuring the preoperative and postoperative paraspinal muscle volume in 26 patients. The preoperative and postoperative cross-sectional area, thickness, and width of the multifidus muscle were measured by computed tomography. The degree of postoperative paraspinal muscle atrophy was significantly greater on the MA side than on the contralateral PIA side (-20.7% and -4.8%, respectively, p<0.01). In conclusion, the PIA for lumbar fusion yielded successful outcomes for the preservation of paraspinal muscle in these 26 patients. We suggest that the success of PIA is due to less manipulation and retraction of the paraspinal muscle and further studies on this technique may help confirm whether less muscle injury has positive effects on the long-term clinical outcome.
PMCID: PMC2693813  PMID: 17728503
Paraspinal Muscle; Paramedian Approach; Muscle Atrophy; Lumbar Spine
10.  Minimal access direct spondylolysis repair using a pedicle screw-rod system: a case series 
Symptomatic spondylolysis is always challenging to treat because the pars defect causing the instability needs to be stabilized while segmental fusion needs to be avoided. Direct repair of the pars defect is ideal in cases of spondylolysis in which posterior decompression is not necessary. We report clinical results using segmental pedicle-screw-rod fixation with bone grafting in patients with symptomatic spondylolysis, a modification of a technique first reported by Tokuhashi and Matsuzaki in 1996. We also describe the surgical technique, assess the fusion and analyze the outcomes of patients.
Case presentation
At Cairo University Hospital, eight out of twelve Egyptian patients’ acute pars fractures healed after conservative management. Of those, two young male patients underwent an operative procedure for chronic low back pain secondary to pars defect. Case one was a 25-year-old Egyptian man who presented with a one-year history of axial low back pain, not radiating to the lower limbs, after falling from height. Case two was a 29-year-old Egyptian man who presented with a one-year history of axial low back pain and a one-year history of mild claudication and infrequent radiation to the leg, never below the knee. Utilizing a standardized mini-access fluoroscopically-guided surgical protocol, fixation was established with two titanium pedicle screws place into both pedicles, at the same level as the pars defect, without violating the facet joint. The cleaned pars defect was grafted; a curved titanium rod was then passed under the base of the spinous process of the affected vertebra, bridging the loose fragment, and attached to the pedicle screw heads, to uplift the spinal process, followed by compression of the defect. The patients were discharged three days after the procedure, with successful fusion at one-year follow-up. No rod breakage or implant-related complications were reported.
Where there is no evidence of frank spondylolisthesis or displacement and pain does not radiate below the knee, we recommend direct repair of the pars interarticularis fracture, especially in young active adults. We describe a modified form of the Buck screw procedure with a minimally invasive, image-guided method of pars interarticularis fixation. The use of image guidance simplifies the otherwise difficult visualization required for pars interarticularis screw placement and allows minimal skin and muscle dissection, which may translate into a more rapid postoperative recovery.
PMCID: PMC3514323  PMID: 23176068
11.  Trans-iliosacral plating for vertically unstable fractures of sacral spine associated with spinopelvic dissociation: A cadaveric study 
Indian Journal of Orthopaedics  2012;46(3):274-278.
The treatment algorithm for sacral fracture associated with vertical shear pelvic fracture has not emerged. Our aim was to study a new approach of fixation for comminuted and vertically unstable fracture pattern with spinopelvic dissociation to overcome inconsistent outcome and avoid complications associated with fixations. We propose fixation with well-contoured thick reconstruction plate spreading across sacrum from one iliac bone to another with fixation points in iliac wing, sacral ala and sacral pedicle on either side. Present biomechanical study tests the four fixation pattern to compare their stiffness to vertical compressive forces.
Materials and Methods:
Dissection was performed on human cadavers through posterior midline paraspinal approach elevating erector spinae from insertion with two flaps. Feasibility of surgical exposure and placement of contoured plate for fixation was evaluated. Ten age and sex matched computed tomography scans of pelvis with both hips were obtained. Reconstructions were performed with advantage windows 4.2 (GE Light Speed QX/I, General Electric, Milwaukee, WI, USA). Using the annotation tools, direct digital CT measurement (0.6 mm increments) of three linear parameters was carried out. Readings were recorded at S2 sacral level. Pelvic CT scans were extensively studied for entry point, trajectory and estimated length for screw placement in S2 pedicle, sacral ala and iliac wing. Readings were recorded for desired angulation of screw in iliac wing ala of sacrum and sacral pedicle with respect to midline. The readings were analyzed by the values of mean and standard deviation. Biomechanical efficacy of fixation methods was studied separately on synthetic bone. Four fixation patterns given below were tested to compare their stiffness to vertical compressive forces: 1) Single S1 iliosacral screw (7.5 mm cancellous screw), 2) Two S1 and S2 iliosacral screws, 3) Isolated trans-iliosacral plate, 4) Trans-iliosacral plate + single S1 iliosacral screw.
Statistical Analysis:
Mean of desired angulation for inserting screws and percentage of displacement on biomechanical testing was evaluated.
Mean angulations for inserting sacral pedicel were 12.3° (SD 2.7°) convergent to midline and divergent of 14° (SD 2.3°) for sacral ala screw and 23° (SD 4.9°) for iliac wing screw. All screws needed to be inserted at an angle of 90° to sacral dorsum to avoid violation of root canals. Cross headed displacement across fracture site was measured and plotted against the applied vertical shear load of 300 N in five cycles each for all the four configurations. Also, the force required for cross headed displacement of 2.5 mm and 5 mm was recorded for all configurations. Transmitted load across both ischial tuberosities was measured to resolve unequal distribution of forces. Taking one screw construct (configuration 1) as standard base reference, trans-iliosacral plate construct (configuration 3) showed equal rigidity to standard reference. Two screw construct (configuration 2) was 12% stronger and trans-iliosacral plate (configuration 4) with screw was 9% stronger at 2.5 mm displacing on 300 N force, while it showed 30% and 6%, respectively, at 5 mm cross-headed displacement.
Trans-iliosacral plating is feasible anatomically, biomechanically and radiologically for sacral fractures associated with vertical shear pelvic fractures. Low profile of plate reduces the risk of hardware prominence and decreases the need for implant removal. Also, the fixation pattern of plate allows to spare mobile lumbosacral junction which is an important segment for spinal mobility. Biomechanical studies revealed that rigidity offered by plate for cross headed displacement across fracture site is equal to sacroiliac screws and further rigidity of construct can be increased with addition of one more screw. There is need for precountered thicker plate in future.
PMCID: PMC3377136  PMID: 22719112
Spinopelvic dissociation; trans-iliosacral plating; unstable sacral spine fractures
12.  Endoscopic Foraminal Decompression for Failed Back Surgery Syndrome under local Anesthesia 
The most common causes of failed back surgery are residual or recurrent herniation, foraminal fibrosis and foraminal stenosis that is ignored, untreated, or undertreated. Residual back ache may also be from facetal causes or denervation and scarring of the paraspinal muscles.1–6 The original surgeon may advise his patient that nothing more can be done on the basis of his opinion that the nerve was visually decompressed by the original surgery, supported by improved post-op imaging and follow-up studies such as EMG and conduction velocity studies. Post-op imaging or electrophysiological assessment may be inadequate to explain all the reasons for residual or recurrent symptoms. Treatment of Failed back surgery by repeat traditional open revision surgery usually incorporates more extensive decompression causing increased instability and back pain, therefore necessitating fusion. The authors, having limited their practice to endoscopic MIS surgery over the last 15-20 years, report on their experience gained during that period to relieve pain by endoscopically visualizing and treating unrecognized causative patho-anatomy in FBSS.7
Thirty consecutive patients with FBSS presenting with back and leg pain that had supporting imaging diagnosis of lateral stenosis and /or residual / recurrent disc herniation, or whose pain complaint was supported by relief from diagnostic and therapeutic injections (Figure 1), were offered percutaneous transforaminal endoscopic discectomy and foraminoplasty over a repeat open procedure. Each patient sought consultation following a transient successful, partially successful or unsuccessful open translaminar surgical treatment for disc herniation or spinal stenosis. Endoscopic foraminoplasty was also performed to either decompress the bony foramen for foraminal stenosis, or foraminoplasty to allow for endoscopic visual examination of the affected traversing and exiting nerve roots in the axilla, also known as the “hidden zone” of Macnab (Figure 2).8, 9 The average follow up time was, average 40 months, minimum 12 months. Outcome data at each visit included Macnab, VAS and ODI.
A diagnostic and therapeutic epidural gram may help identify unrecognized lateral recess stenosis underestimated by MRI. An excellent result from a therapeutic block lends excellent prognosis for a more lasting and “permanent” result from transforaminal endoscopic lateral recess decompression.
Kambin's Triangle provides access to the “hidden zone” of Macnab by foraminoplasty. The foramen and lateral recess is decompressed by removing the ventral aspect and tip of the superior articular process to gain access to the axilla between the traversing and exiting nerve. FBSS contains patho-anatomy in the axilla between the traversing and exiting nerve that hides the pain generators of FBSS.
The average pre-operative VAS improved from 7.2 to 4.0, and ODI 48% to 31%. While temporary dysesthesia occurred in 4 patients in the early post-operative period, all were happy, as all received additional relief of their pre-op symptoms. They were also relieved to be able to avoid “open” decompression or fusion surgery.
Conclusions / Level of Evidence 3
The transforaminal endoscopic approach is effective for FBSS due to residual/recurrent HNP and lateral stenosis. Failed initial index surgery may involve failure to recognize patho-anatomy in the axilla of the foramen housing the traversing and the exiting nerve, including the DRG, which is located cephalad and near the tip of SAP.10 The transforaminal endoscopic approach effectively decompresses the foramen and does not further destabilize the spine needing stabilization.11 It also avoids going through the previous surgical site.
Clinical Relevance
Disc narrowing as a consequence of translaminar discectomy and progressive degenerative narrowing and spondylolisthesis (Figure 3) as a natural history of degenerative disc disease can lead to central and lateral stenosis. The MRI may underestimate the degree of stenosis from a bulging or a foraminal disc protrusion and residual lateral recess stenosis. Pain can be diagnosed and confirmed by evocative discography and by clinical response to transforaminal diagnostic and therapeutic steroid injections.12 Foraminal endoscopic decompression of the lateral recess is a MIS technique that does not “burn bridges” for a more conventional approach and it adds to the surgical armamentarium of FBSS.
Cadaver Illustration of Foraminal Stenosis (courtesy of Wolfgang Rauschning). As the disc narrows, the superior articular process impinges on the exiting nerve and DRG, creating lateral recess stenosis, lumbar spondylosis, and facet arthrosis.
PMCID: PMC4325507
Failed Back Surgery Syndrome(FBSS); Hidden zone; Foraminal decompression; Recurrent herniation; Lateral stenosis; Foraminal osteophyte
13.  Clinical application of the paraspinal erector approach for spinal canal decompression in upper lumber burst fractures 
Percutaneous pedicle screw fixation is commonly used for upper lumber burst fractures. The direct decompression remains challenging with this minimally invasive surgery. The objective was to evaluate a novel paraspinal erector approach for effective and direct decompression in patients with canal compromise and neurologic deficit.
Patients (n = 21) with neurological deficiency and Denis B type upper lumbar burst fracture were enrolled in the study, including 14 cases in the L1 and 7 cases in the L2. The patients underwent removal of bone fragments from the spinal canal through intervertebral foramen followed by short-segment fixation. Evaluations included surgery-related, such as duration of surgery and blood loss, and 12-month follow-up, such as the kyphotic angle, the height ratio of the anterior edge of the vertebra, the ratio of sagittal canal compromise, visual analog scale (VAS), Oswestry Disability Index (ODI), and Frankel scores.
All patients achieved direct spinal canal decompression using the paraspinal erector approach followed by percutaneous pedicle screw fixation. The mean operation time (SD) was 173 (23) min, and the mean (SD) blood loss was 301 (104) ml. Significant improvement was noted in the kyphotic angle, 26.2 ± 8.7 prior to operation versus 9.1 ± 4.7 at 12 months after operation (p <0.05); the height ratio of the anterior edge of the injured vertebra, 60 ± 16% versus 84 ± 9% (p <0.05); and the ratio of sagittal canal compromise, 46.5 ± 11.4% versus 4.3 ± 3.6% (p <0.05). Significant improvements in VAS (7.3 ± 1.2 vs. 1.9 ± 0.7, p <0.05), ODI (86.7 ± 5.8 vs. 16.7 ± 5.1, p <0.05), and Frankel scores were also noted.
The paraspinal erector approach was effective for direct spinal canal decompression with minimal injury in the paraspinal muscles or spine. Significant improvements in spinal function and prognostics were achieved after the percutaneous pedicle screw fixation.
PMCID: PMC4240844  PMID: 25387608
Erector spinae; Direct spinal canal decompression; Minimally invasive spine surgery; Surgical approach; Upper lumber burst fractures
14.  Benefit and accuracy of intraoperative 3D-imaging after pedicle screw placement: a prospective study in stabilizing thoracolumbar fractures 
European Spine Journal  2009;18(10):1469-1477.
Internal fixation is the established dorsal standard procedure for the treatment of thoracolumbar fractures. The main problem of the procedure is the false positioning of the pedicle screws. The exact determination of pedicle screws has up to now only been possible through postoperative computed tomography. This study was intended to clarify the diagnostic value of intraoperative 3D scans after pedicle screw implantation in thoracolumbar spine surgery. The direct intraoperative consequences of the 3D scans are reported and the results of the 3D scans are compared with the postoperative computed tomography images. Intraoperative 3D scans were prospectively carried out from June 2006 to October 2008 on 95 patients with fractures of the thoracolumbar spine that have been treated with internal fixation. Screws positions were categorised intraoperatively, screws in relevant malposition were repositioned immediately. A computed tomography of the involved spinal section was carried out postoperatively for all patients. The positions of the pedicle screws were determined and compared in the axial reconstructions of both procedures. Four hundred and fourteen pedicles with enclosed screws were evaluated by the 3D scans. The time needed for carrying out the 3D scan amounts to an average of 8.2 min. Eleven screws (2.7%) in ten patients were primarily intraoperatively repositioned on the basis of the 3D scan evaluation. Two of 95 patients had to have false positions of the screws revised secondarily following evaluation of the computed tomographies. The secondary postoperative revision rate of the patients amounts to 2.1%. In relation to the number of screws, this is a revision rate of 0.5%. The postoperative computed tomographies showed 323 pedicles without cortical penetration by the screws (78.0%). Ninety-one screws penetrated the pedicle wall (22%). It was possible to postoperatively compare the position classifications of 406 pedicle screws. The CT showed 378 correct screw positions, while 28 screws were positioned falsely. On the basis of the 3D scans, 376 of 378 correct positions were correctly assessed. Twenty-one of 28 false positions could be correctly classified. The sensitivity of all 3D scans reached 91.3% and the specificity 98.2%. The position of 97.8% of the pedicle screws was correctly recognised by the intraoperative 3D scan. Nine screws were classified falsely (2.2%). The comparison of the classification results showed significantly higher error findings by the 3D scan in the spinal section T1–10 (P = 0.014). The image quality of the 3D scan correlates significantly with the width of the scanned pedicle, with the body mass index, the scanned spinal section and the extent of the fixation assembly. 3D scans showed a high accuracy in predicting pedicle screw position. Primary false placement of screws and primary neurovascular damage cannot be avoided. But intraoperative evaluation of the 3D scans resulted in a primary revision rate of 2.7% of the pedicle screws and we could lower the secondary revision rate to 0.5%.
PMCID: PMC2899379  PMID: 19513764
Three-dimensional fluoroscopy; Intraoperative 3D-imaging; Pedicle screws; Thoracolumbar fracture; Spine
15.  The dynamic neutralization system for the spine: a multi-center study of a novel non-fusion system 
European Spine Journal  2002;11(Suppl 2):S170-S178.
Various forms of lumbar instability require a surgical stabilization. As an alternative to fusion, a mobile, dynamic stabilization restricting segmental motion would be advantageous in various indications, allowing greater physiological function and reducing the inherent disadvantages of rigid instrumentation and fusion. The dynamic neutralization system for the spine (Dynesys) is a pedicle screw system for mobile stabilization, consisting of titanium alloy screws connected by an elastic synthetic compound, controlling motion in any plane (non-fusion system). This prospective, multi-center study evaluated the safety and efficacy of Dynesys in the treatment of lumbar instability conditions, evaluating pre- and post-operative pain, function, and radiological data on a consecutive series of 83 patients. Indications consisted of unstable segmental conditions, mainly combined with spinal stenosis (60.2%) and with degenerative discopathy (24.1%), in some cases with disc herniation (8.4%), and with revision surgery (6.0%). Thirty-nine patients additionally had degenerative spondylolisthesis, and 30 patients had undergone previous lumbar surgery. In 56 patients instrumentation was combined with direct decompression. The mean age at operation was 58.2 (range 26.8–85.3) years; the mean follow-up time was 38.1 months (range 11.2–79.1 months). There were nine complications unrelated to the implant, and one due to a screw malplacement. Four of them required an early surgical reintervention. Additional lumbar surgery in the follow-up period included: implant removal and conversion into spinal fusion with rigid instrumentation for persisting pain in three cases, laminectomy of an index segment in one case and screw removal due to loosening in one case. In seven cases, radiological signs of screw loosening were observed. In seven cases, adjacent segment degeneration necessitated further surgery. Mean pain and function scores improved significantly from baseline to follow-up, as follows: back pain scale from 7.4 to 3.1, leg pain scale from 6.9 to 2.4, and Oswestry Disability Index from 55.4% to 22.9%. These study results compare well with those obtained by conventional procedures; in addition to which, mobile stabilization is less invasive than fusion. Long-term screw fixation is dependent on correct screw dimension and proper screw positioning. The natural course of polysegmental disease in some cases necessitates further surgery as the disease progresses. Dynamic neutralization proved to be a safe and effective alternative in the treatment of unstable lumbar conditions.
PMCID: PMC3611570  PMID: 12384741
Lumbar spine Surgical treatment Non-fusion Instrumentation Instability
16.  Minimally invasive one-level lumbar decompression and fusion surgery with posterior instrumentation using a combination of pedicle screw fixation and transpedicular facet screw construct 
Minimally invasive lumbar spine fusion surgery has gained popularity in recent years. Routinely, this technique requires bilateral parasagittal incisions for decompression, interbody fusion, and posterior instrumentation. The following study is a description of a new minimally invasive technique for one-level transforaminal lumbar interbody fusion (TLIF) using a unilateral parasagittal incision (Wiltse approach), with placement of pedicle screws and then a percutaneous transpedicular facet screw insertion on the contralateral side. The biomechanical stability of this posterior construct will be discussed while the efficacy and complications of this technique have been examined.
Forty patients underwent this new technique of one-level TLIF with posterior instrumentation using unilateral pedicle screw fixation supplemented with contralateral percutaneous transpedicular facet screw construct. Data regarding surgical time, estimated blood loss (EBL), hospital length of stay (LOS), and complications related to the posterior instrumentation are recorded.
The average surgical time of this new procedure was 124 minutes; average EBL was 140 cc; average hospital LOS was 3 days. Two patients developed new leg pain on the side where the facet screw had been placed. Both patients had the facet screw removed.
This novel technique of unilateral pedicle screw fixation combined with contralateral percutaneous transpedicular facet screw construct has further reduced the amount of normal tissue injury while maintaining the same biomechanical advantages of bilateral pedicle screw fixation. However, caution is needed during the placement of the percutaneous facet screw in order to avoid nerve root injury.
PMCID: PMC3814991  PMID: 24255796
Minimally invasive spine surgery; percutaneous facet screw; transforaminal interbody fusion; Wiltse approach
17.  Minimally invasive anterior transarticular screw fixation and microendoscopic bone graft for atlantoaxial instability 
European Spine Journal  2012;21(8):1568-1574.
Even though transarticular screw (TAS) fixation has been commonly used for posterior C1–C2 arthrodesis in both traumatic and non-traumatic lesions, anterior TAS fixation C1–2 is a less invasive technique as compared with posterior TAS which produces significant soft tissue injury, and there were few reports on percutaneous anterior TAS fixation and microendoscopic bone graft for atlantoaxial instability. The goals of our study were to describe and evaluate a new technique for anterior TAS fixation of the atlantoaxial joints for traumatic atlantoaxial instability by analyzing radiographic and clinical outcomes.
This was a retrospective study of seven consecutive patients with C1–C2 instability due to upper cervical injury treated by a minimally invasive procedure from May 2007 to August 2009. Bilateral anterior TAS were inserted by the percutaneous approach under Iso-C3D fluoroscopic control. The atlantoaxial joint space was prepared for morselized autogenous bone graft under microendoscopy. The data for analysis included time after the injuries, operating time, intraoperative blood loss, X-ray exposure time, clinical results, and complications. Radiographic evaluation included the assessment of atlantoaxial fusion rate and placement of TAS. Bone fusion of the atlantoaxial joints was assessed by flexion extension lateral radiographs and 1-mm thin-slice computed tomography images as radiographic results. Clinical assessment was done by analyzing the recovery state of clinical presentation from the preoperative period to the last follow-up and by evaluating complications.
A total of 14 screws were placed correctly. The atlantoaxial solid fusion without screw failure was confirmed by CT scan in seven cases after a mean follow-up of 27.5 months (range 18–45 months). All patients with associated clinical presentation made a recovery without neurologic sequelae. Postoperative dysphagia occurred and disappeared in two cases within 5 days after surgery. There were no other complications during the follow-up period.
Percutaneous anterior TAS fixation and microendoscopic bone graft could be an option for achieving C1–C2 stabilization with several potential advantages such as less tissue trauma and better accuracy. Bilateral TAS fixation and morselized autograft affords effective fixation and solid fusion by a minimally invasive approach.
PMCID: PMC3535255  PMID: 22315033
Cervical instability; Atlantoaxial fixation; Transarticular screw; Fusion; Minimally invasive spine surgery
18.  A Comparative Evaluation of Fixation Techniques in Anterior Mandibular Fractures Using 2.0 mm Monocortical Titanium Miniplates Versus 2.4 mm Cortical Titanium Lag Screws 
To compare the efficacy and surgical outcome of treatment of anterior mandibular fracture using either 2.0 mm titanium miniplate or 2.4 mm titanium lag screw technique.
Materials and Methods
A total of 30 patients were managed by open reduction and internal fixation utilizing the miniplate and lag screw technique for fractures of anterior mandible. The patients were randomly divided into two groups. Group I: (15 patients) were treated with Leibinger, 2.0 mm titanium mini plates system with self-tapping screws and Group II: (15 patients) were treated with 2.4 mm cortical lag screw (Synthes). Intraoperatively duration of surgery was measured from the time incision was placed till the closure of wound. Subsequent follow up was done at 3, 6, 12, 24 weeks, postoperatively. During every follow up, patients were assessed clinically for malocclusion, neurosensory deficit, biting efficiency, implant failure, mal-union/non-union. Pre and postoperative radiographs were taken to assess the gap between fracture segments. Results were evaluated using Chi square and the unpaired t test.
In our study, the mean duration of surgery (hours) was 1.97 ± 0.52 for group I and 1.26 ± 0.55 for group II. The difference was found to be statistically significant (p value 0.001). i.e. more time was taken in case of surgery with mini-plates when compared to the lag screw. Short surgical procedure reduces the incidence of infectious complications, which significantly lowers the financial burden. The mean post-operative radiographic distance between all measuring points were considerably more in case of mini-plate group as compared to lag screw group. Lag screw group showed faster improvement in terms of biting efficiency as compared to mini-plate group which showed a tendency to masticate only medium hard food items by 24 weeks. In both groups, no postoperative malocclusion was noted. In initial weeks, neurosensory deficit was seen more in mini-plate group as compared to lag screw group but after six weeks all patients showed improvement in neurosensory function without any permanent nerve damage.
According to this prospective study, rigid internal fixation provided by lag screw technique for anterior mandibular fracture offers several advantages over conventional bone plating. It is an excellent means of achieving rapid and safe fixation which is followed by primary bone healing in anterior mandibular fractures, without any major complications.
PMCID: PMC3485465  PMID: 24293938
Mandibular fractures; Miniplates; Compression osteosynthesis; Lag screw technique
19.  Posterior lumbar interbody fusion using one diagonal fusion cage with transpedicular screw/rod fixation 
European Spine Journal  2003;12(2):173-177.
Posterior lumbar interbody fusion (PLIF) using threaded cages has gained wide popularity for lumbosacral spinal disease. Our biomechanical tests showed that PLIF using a single diagonal cage with unilateral facetectomy does add a little to spinal stability and provides equal or even higher postoperative stability than PLIF using two posterior cages with bilateral facetectomy. Studies also demonstrated that cages placed using a posterior approach did not cause the same increase in spinal stiffness seen with pedicle screw instrumentation, and we concluded that cages should not be used posteriorly without other forms of fixation. On the other hand, placement of two cages using a posterior approach does have the disadvantage of risk to the bilateral nerve roots. We therefore performed a prospective study to determine whether PLIF can be accomplished by utilizing a single diagonal fusion cage with the application of supplemental transpedicular screw/rod instrumentation. Twenty-seven patients underwent a PLIF using one single fusion cage (BAK, Sulzer Spine-Tech, Minneapolis, MN, USA) inserted posterolaterally and oriented anteromedially on the symptomatic side with unilateral facetectomy and at the same level supplemental fixation with a transpedicular screw/rod system. The internal fixation systems included 12 SOCON spinal systems (Aesculap AG, Germany) and 15 TSRH spinal systems (Medtronic Sofamor Danek, USA). The inclusion criteria were grade 1 to 2 lumbar isthmic spondylolisthesis, lumbar degenerative spondylolisthesis, and recurrent lumbar disc herniations with instability. Patients had at least 1 year of low back pain and/or unilateral sciatica and a severely restricted functional ability in individuals aged 28–55 years. Patients with more than grade 2 spondylolisthesis or adjacent-level degeneration were excluded from the study. Patients were clinically assessed prior to surgery by an independent assessor; they were then reassessed at 1, 3, 6, 12, 18, and 24 months postoperatively by the same assessor and put into four categories: excellent, good, fair, and poor. Operative time, blood loss, hospital expense, and complications were also recorded. All patients achieved successful radiographic fusion at 2 years, and this was achieved at 1 year in 25 out of 27 patients. At 2 years, clinical results were excellent in 15patients, good in 10, fair in 1, and poor in 1. Regarding complications, one patient had a postoperative motor and sensory deficit of the nerve root. Reoperation was required in one patient due to migration of pedicle screws. No implant fractures or deformities occurred in any of the patients. PLIF using diagonal insertion of a single threaded cage with supplemental transpedicular screw/rod instrumentation enables sufficient decompression and solid interbody fusion to be achieved with minimal invasion of the posterior spinal elements. It is a clinically safer, easier, and more economical means of accomplishing PLIF.
PMCID: PMC3784842  PMID: 12709855
Lumbar Fusion cage Implant Transpedicular screw Interbody
20.  Comparative study of PILF and TLIF treatment in adult degenerative spondylolisthesis 
European Spine Journal  2008;17(10):1311-1316.
This study is to compare the therapeutic effect of posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) with pedicle screw fixation on treatment in adult degenerative spondylolisthesis. A retrospective analysis of 187 patients to compare the complications and associated predictive factors of the two techniques of one level lumbar fusion. Ninety-one had PLIF with two cages and pedicle fixation (group 1), and ninety-six had TLIF with one cage and pedicle fixation (group 2). The two groups had similar age and sex distribution, and level of pain. Inclusion criteria and outcome measurements were identical in both groups. The two groups were operated on with autograft and cage with pedicle fixation. Before surgery and at the 2-year follow-up, pain (VAS) and functional disability (JOA) were quantified. The results showed there were no intraoperative deaths in our study. In the end 176 cases had 2-year follow-up while 11 cases were lost to follow-up. The follow-up rate was 93.4% (85/91) in the PLIF group and 94.8% (91/96) in the TLIF group. All patients had bone fusion, and there were no cases of cage extrusion. The pain index improved from 7.08 ± 1.13 to 2.84 ± 0.89 in PLIF patients and improved from 7.18 ± 1.09 to 2.84 ± 0.91 in TLIF patients (P < 0.001). There were 42 cases of excellent, 29 cases of good, 11 cases of general, and 3 cases of poor results in PLIF group. There were 46 cases of excellent, 31 case of good, 12 case of general, and 2 cases of poor results in TLIF group. The JOA score in all patients was 84.1% of good or excellent (83.5% in PLIF and 84.6% in TLIF, P > 0.05). The average preoperative slip was 30.1 ± 7.2% in PLIF group while in the TLIF it was 31.4 ± 8.3%. Immediately post operatively it was reduced to 7.3 ± 2.1% and 7.4 ± 2.7% and at last F/U it was 8.1 ± 2.8% and 8.2 ± 2.6%, respectively. The average of reduction rate was 75.2 ± 6.4% in PLIF and 75.4 ± 6.2 in TLIF on the initial post operatively X-ray, and 72.6 ± 5.2% and 72.4 ± 5.4% on the follow-up. The percentage rate, reduction rate and lost of reduction rate between the two groups was similar (P > 0.05). The average pre operative disk and foramen height in the PLIF group improved from 6.8 ± 2.3 and 14.2 ± 1.7 preoperatively to 11.6 ± 1.5 and 18.7 ± 1.8 post operatively, respectively. At last follow up there was minimal lost of correction down to 11.24 ± 1.2 and 18.1 ± 1.8, respectively. Similarly in the TLIF group, pre operative disk and foramen height were improved from 6.7 ± 1.7 and 14.1 ± 1.8 to 11.4 ± 1.6 and 18.5 ± 1.6 immediately post operative. At last follow up minimal lost of correction was noted with average disc height of 11.3 ± 1.4 and 18.2 ± 1.7. Both techniques achieve statistical significance in restoration of disc and foraminal (P < 0.01); however, there was no statistical difference between the two techniques. In conclusion, interbody fusion with either a PLIF technique or a TLIF technique provides good outcomes in the treatment of adult degenerative spondylolisthesis. The TLIF procedure is simpler and is as safe and effective as the PLIF technique.
PMCID: PMC2556474  PMID: 18685873
Spondyolisthesis; Interverterbral fusion; Internal fixation
21.  Anterior Dislodgement of a Fusion Cage after Transforaminal Lumbar Interbody Fusion for the Treatment of Isthmic Spondylolisthesis 
Transforaminal lumbar interbody fusion (TLIF) is commonly used procedure for spinal fusion. However, there are no reports describing anterior cage dislodgement after surgery. This report is a rare case of anterior dislodgement of fusion cage after TLIF for the treatment of isthmic spondylolisthesis with lumbosacral transitional vertebra (LSTV). A 51-year-old man underwent TLIF at L4-5 with posterior instrumentation for the treatment of grade 1 isthmic spondylolisthesis with LSTV. At 7 weeks postoperatively, imaging studies demonstrated that banana-shaped cage migrated anteriorly and anterolisthesis recurred at the index level with pseudoarthrosis. The cage was removed and exchanged by new cage through anterior approach, and screws were replaced with larger size ones and cement augmentation was added. At postoperative 2 days of revision surgery, computed tomography (CT) showed fracture on lateral pedicle and body wall of L5 vertebra. He underwent surgery again for paraspinal decompression at L4-5 and extension of instrumentation to S1 vertebra. His back and leg pains improved significantly after final revision surgery and symptom relief was maintained during follow-up period. At 6 months follow-up, CT images showed solid fusion at L4-5 level. Careful cage selection for TLIF must be done for treatment of spondylolisthesis accompanied with deformed LSTV, especially when reduction will be attempted. Banana-shaped cage should be positioned anteriorly, but anterior dislodgement of cage and reduction failure may occur in case of a highly unstable spine. Revision surgery for the treatment of an anteriorly dislodged cage may be effectively performed using an anterior approach.
PMCID: PMC3809439  PMID: 24175028
Cage; Transforaminal lumbar interbody fusion; Spondylolisthesis; Lumbosacral spine; Transitional vertebra
22.  2D-fluoroscopic navigated percutaneous screw fixation of pelvic ring injuries - a case series 
Screw fixation of pelvic ring fractures is a common, but demanding procedure and navigation techniques were introduced to increase the precision of screw placement. The purpose of this case series was the evaluation of screw misplacement rate and functional outcome of percutaneous screw fixation of pelvic ring disruptions using a 2D navigation system.
Between August 2004 and December 2007, 44 of 442 patients with pelvic injuries were included for closed reduction and percutaneous screw fixation of disrupted pelvic ring lesions using an optoelectronic 2D-fluoroscopic based navigation system. Operating and fluoroscopy time were measured, as well as peri- and postoperative complications documented. Screw position was assessed by postoperative CT scans. Quality of live was evaluated by SF 36-questionnaire in 40 of 44 patients at mean follow up 15.5 ± 1.2 month.
56 iliosacral- and 29 ramus pubic-screws were inserted (mean operation time per screw 62 ± 4 minutes, mean fluoroscopy time per screw 123 ± 12 seconds). In post-operative CT-scans the screw position was assessed and graded as follows: I. secure positioning, completely in the cancellous bone (80%); II. secure positioning, but contacting cortical bone structures (14%); III. malplaced positioning, penetrating the cortical bone (6%). The malplacements predominantly occurred in bilateral overlapping screw fixation. No wound infection or iatrogenic neurovascular damage were observed. Four re-operations were performed, two of them due to implant-misplacement and two of them due to implant-failure.
2D-fluoroscopic navigation is a safe tool providing high accuracy of percutaneous screw placement for pelvic ring fractures, but in cases of a bilateral iliosacral screw fixation an increased risk for screw misplacement was observed. If additional ramus pubic screw fixations are performed, the retrograde inserted screws have to pass the iliopubic eminence to prevent an axial screw loosening.
PMCID: PMC2916892  PMID: 20609243
23.  Cost-effectiveness of decompression according to Gill versus instrumented spondylodesis in the treatment of sciatica due to low grade spondylolytic spondylolisthesis: A prospective randomised controlled trial [NTR1300] 
Nerve root decompression with instrumented spondylodesis is the most frequently performed surgical procedure in the treatment of patients with symptomatic low-grade spondylolytic spondylolisthesis. Nerve root decompression without instrumented fusion, i.e. Gill's procedure, is an alternative and less invasive approach. A comparative cost-effectiveness study has not been performed yet. We present the design of a randomised controlled trial on cost-effectiveness of decompression according to Gill versus instrumented spondylodesis.
All patients (age between 18 and 70 years) with sciatica or neurogenic claudication lasting more than 3 months due to spondylolytic spondylolisthesis grade I or II, are eligible for inclusion. Patients will be randomly allocated to nerve root decompression according to Gill, either unilateral or bilateral, or pedicle screw fixation with interbody fusion. The main primary outcome measure is the functional assessment of the patient measured with the Roland Disability Questionnaire for Sciatica at 12 weeks and 2 years. Other primary outcome measures are perceived recovery and intensity of leg pain and low back pain. The secondary outcome measures include, incidence of re-operations, complications, serum creatine phosphokinase, quality of life, medical consumption, costs, absenteeism, work perception, depression and anxiety, and treatment preference. The study is a randomised prospective multicenter trial in which two surgical techniques are compared in a parallel group design. Patients and research nurse will not be blinded during the follow-up period of 2 years.
Currently, nerve root decompression with instrumented fusion is the golden standard in the surgical treatment of low-grade spondylolytic spondylolisthesis, although scientific proof justifying instrumented spondylodesis over simple decompression is lacking. This trial is designed to elucidate the controversy in best surgical treatment of symptomatic patients with low-grade spondylolytic spondylolisthesis.
PMCID: PMC2570682  PMID: 18822175
24.  The Quantitative Analysis of Back Muscle Degeneration after Posterior Lumbar Fusion: Comparison of Minimally Invasive and Conventional Open Surgery 
Asian Spine Journal  2009;3(2):89-95.
Study Design
Prospective controlled study.
The results of conventional open surgery was compared with those from minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) for lumbar fusion to determine which approach resulted in less postoperative paraspinal muscle degeneration.
Overview of Literature
MI TLIF is new surgical technique that appears to minimize iatrogenic injury. However, there aren't any reports yet that have quantitatively analyzed and proved whether there's difference in back muscle injury and degeneration between the minimally invasive surgery and conventional open surgery in more than 1 year follow-up after surgery.
This study examined a consecutive series of 48 patients who underwent lumbar fusion in our hospital during the period, March 2006 to March 2008, with a 1-year follow-up evaluation using MRI. There were 17 cases of conventional open surgery and 31 cases of MI-TLIF (31 cases of single segment fusion and 17 cases of multi-segment fusion). The digital images of the paravertebral back muscles were analyzed and compared using the T2-weighted axial images. The point of interest was the paraspinal muscle of the intervertebral disc level from L1 to L5. Picture archiving and communication system viewing software was used for quantitative analysis of the change in fat infiltration percentage and the change in cross-sectional area of the paraspinal muscle, before and after surgery.
A comparison of the traditional posterior fusion method with MI-TLIF revealed single segment fusion to result in an average increase in fat infiltration in the paraspinal muscle of 4.30% and 1.37% and a decrease in cross-sectional area of 0.10 and 0.07 before and after surgery, respectively. Multi-segment fusion showed an average 7.90% and 2.79% increase in fat infiltration and a 0.16 and 0.10 decrease in cross-sectional area, respectively. Both single and multi segment fusion showed less change in the fat infiltration percentage and cross-sectional area, particularly in multi segment fusion. There was no significant difference between the two groups in terms of the radiologic results.
A comparison of conventional open surgery with MI-TLIF upon degeneration of the paraspinal muscle with a 1 year follow-up evaluation revealed that both single and multi segment fusion showed less change in fat infiltration percentage and cross-sectional area in the MI-TLIF but there was no significant difference between the two groups. This suggests that as time passes after surgery, there is no significant difference in the level of degeneration of the paraspinal muscle between surgical techniques.
PMCID: PMC2852079  PMID: 20404953
Paraspainal muscle; Fat degeneration; MRI; Posterior fusion
25.  Solid and hollow pedicle screws affect the electrical resistance: A potential source of error with stimulus-evoked electromyography 
Indian Journal of Orthopaedics  2013;47(4):352-356.
Although stimulus evoked electromyography (EMG) is commonly used to confirm the accuracy of pedicle screw placement. There are no studies to differentiate between solid screws and hollow screws to the electrical resistance of pedicle screws. We speculate that the electrical resistance of the solid and hollow pedicle screws may be different and then a potential source of error with stimulus-evoked EMG may happen.
Materials and Methods:
Resistance measurements were obtained from 12 pedicle screw varieties (6 screws of each manufacturer) across the screw shank based on known constant current and measured voltage. The voltage was measured 5 times at each site.
Resistance of all solid screws ranged from 0.084 Ω to 0.151 Ω (mean =0.118 ± 0.024 Ω) and hollow screws ranged from 0.148 Ω to 0.402 Ω (mean = 0.285 ± 0.081 Ω). There was a significant difference of resistance between the solid screws and hollow screws (P < 0.05). The screw with the largest diameter no matter solid screws or hollow screws had lower resistance than screws with other diameters. No matter in solid screws group or hollow screws group, there were significant differences (P < 0.05) between the 5.0 mm screws and 6.0 mm screws, 6.0 mm screws and 7.0 mm screws, 5.0 mm screws and 7.0 mm screws, 4.5 mm screws and 5.5 mm screws, 5.5 mm screws and 6.5 mm screws, 4.5 mm screws and 6.5 mm screws. The resistance of hollow screws was much larger than the solid screws in the same diameter group (P < 0.05).
Hollow pedicle screws have the potential for high electrical resistance compared to the solid pedicle screws and therefore may affect the EMG response during stimulus-evoked EMG testing in pedicle screw fixation especially in minimally invasive percutaneous pedical screw fixation surgery.
PMCID: PMC3745688  PMID: 23960278
Electrical resistance; electromyography; pedicle screw; percutaneous pedicle screw

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