Computer tomography assessment of pedicle screw placement in thoracic spine: comparison between free hand and a generic 3D-based navigation techniques

Introduction

Although pedicle screw fixation is a well-established technique for the lumbar spine, screw placement in the thoracic spine is more challenging because of the smaller pedicle size and more complex 3D anatomy. The intraoperative use of image guidance devices may allow surgeons a safer, more accurate method for placing thoracic pedicle screws while limiting radiation exposure. This generic 3D imaging technique is a new generation intraoperative CT imaging system designed without compromise to address the needs of a modern OR.

Aim

The aim of our study was to check the accuracy of this generic 3D navigated pedicle screw implants in comparison to free hand technique described by Roy-Camille at the thoracic spine using CT scans.

Material and methods

The material of this study was divided into two groups: free hand group (group I) (18 patients; 108 screws) and 3D group (27 patients; 100 screws). The patients were operated upon from January 2009 to March 2010. Screw implantation was performed during internal fixation for fractures, tumors, and spondylodiscitis of the thoracic spine as well as for degenerative lumbar scoliosis.

Results

The accuracy rate in our work was 89.8 % in the free hand group compared to 98 % in the generic 3D navigated group.

Conclusion

In conclusion, 3D navigation-assisted pedicle screw placement is superior to free hand technique in the thoracic spine.     

CT-navigation versus fluoroscopy-guided placement of pedicle screws at the thoracolumbar spine: single center experience of 4,500 screws

Purpose

Single center evaluation of the placement accuracy of thoracolumbar pedicle screws implanted either with fluoroscopy or under CT-navigation using 3D-reconstruction and intraoperative computed tomography control of the screw position. There is in fact a huge variation in the reported placement accuracy of pedicle screws, especially concerning the screw placement under conventional fluoroscopy most notably due to the lack of the definition of screw misplacement, combined with a potpourri of postinstrumentation evaluation methods.

Methods

The operation data of 1,006 patients operated on in our clinic between 1995 and 2005 is analyzed retrospectively. There were 2,422 screws placed with the help of CT-navigation compared to 2,002 screws placed under fluoroscopy. The postoperative computed tomography images were reviewed by a radiologist and an independent spine surgeon.

Results

In the lumbar spine, the placement accuracy was 96.4 % for CT-navigated screws and 93.9 % for pedicle screws placed under fluoroscopy, respectively. This difference in accuracy was statistically significant (Fishers Exact Test, p = 0.001). The difference in accuracy became more impressing in the thoracic spine, with a placement accuracy of 95.5 % in the CT-navigation group, compared to 79.0 % accuracy in the fluoroscopy group (p < 0.001).

Conclusion

This study underlines the relevance of CT-navigation-guided pedicle screw placement, especially when instrumentation of the middle and upper thoracic spine is carried out.     

Biomechanical analysis of a novel posterior construct in a transforaminal lumbar interbody fusion model an in vitro study

Background context

Spinal fusion is a commonly performed surgical procedure. It is used to treat a variety of spinal pathologies, including degenerative disease, trauma, spondylolisthesis, and deformities. A mechanically stable spine provides an ideal environment for the formation of a fusion mass. Instrumented spinal fusion allows early ambulation with minimal need for a postoperative external immobilizer. Several biomechanical and clinical studies have evaluated the stability offered by different posterior instrumentation techniques and the effects of reduced instrumentation.

Purpose

The aim of the study was to compare the biomechanics of a novel pedicle and translaminar facet screw (TLFS) construct. Also, in this study, comparisons were made with the more common pedicle screw/TLFS constructs for posterior fixation.

Study design

Human cadaveric lumbar spines were tested in an in vitro flexibility experiment to investigate the biomechanical stability provided by a novel pedicle and TLFS construct after transforaminal lumbar interbody fusion (TLIF).

Methods

Seven fresh human lumbar spines (L2–L5) were tested by applying pure moments of ±8 Nm. After intact specimen testing, a left-sided TLIF with a radiolucent interbody spacer was performed at L3–L4. Each specimen was then tested for the following constructs: bilateral pedicle screws (BPS) and rods at L3–L4; unilateral pedicle screws (UPS) and rods at L3–L4; UPS and rods and TLFS at L3–L4 (UPS+TLFS); and unilateral single pedicle screw and TLFS and rod at L3–L4 (V construct). The L3–L4 range of motion (ROM) and stiffness for each construct were obtained by applying pure moments in flexion, extension, lateral bending, and axial rotation.

Results

All instrumented constructs significantly reduced ROM in flexion-extension and lateral bending compared with the intact specimen. In axial rotation, only BPS constructs significantly reduced ROM compared with intact specimen. The V construct was able to achieve more reduction in ROM compared with UPS construct and was comparable to UPS+TLFS construct. Unilateral pedicle screws construct was the least stable in all loading modes and was significantly different than BPS construct in lateral bending.

Conclusions

The V construct exhibited enhanced stability compared with UPS construct in all loading modes. It provides bilateral fixation and preserves the anatomic integrity of the superior facet joint. The novel construct may offer advantages of less invasiveness, significant reduction in operation time, duration of hospitalization, and costs of implants, which would require further clinical evaluation.     

Influence of the screw augmentation technique and a diameter increase on pedicle screw fixation in the osteoporotic spine: pullout versus fatigue testing

Purpose

For posterior spinal stabilization, loosening of pedicle screws at the bone-screw interface is a clinical complication, especially in the osteoporotic population. Axial pullout testing is the standard pre-clinical testing method for new screw designs although it has questioned clinical relevance. The aim of this study was to determine the fixation strength of three current osteoporotic fixation techniques and to investigate whether or not pullout testing results can directly relate to those of the more physiologic fatigue testing.

Methods

Thirty-nine osteoporotic, human lumbar vertebrae were instrumented with pedicle screws according to four treatment groups: (1) screw only (control), (2) prefilled augmentation, (3) screw injected augmentation, and (4) unaugmented screws with an increased diameter. Toggle testing was first performed on one pedicle, using a cranial-caudal sinusoidal, cyclic (1.0 Hz) fatigue loading applied at the screw head. The initial compressive forces ranged from 25 to 75 N. Peak force increased stepwise by 25 N every 250 cycles until a 5.4-mm screw head displacement. The contralateral screw then underwent pure axial pullout (5 mm/min).

Results

When compared to the control group, screw injected augmentation increased fatigue force (27 %, p = 0.045) while prefilled augmentation reduced fatigue force (?7 %, p = 0.73). Both augmentation techniques increased pullout force compared to the control (ps < 0.04). Increasing the screw diameter by 1 mm increased pullout force (24 %, p = 0.19), fatigue force (5 %, p = 0.73), and induced the least stiffness loss (?29 %) from control.

Conclusions

For the osteoporotic spine, screw injected augmentation showed the best biomechanical stability. Although pullout testing was more sensitive, the differences observed were not reflected in the more physiological fatigue testing, thus casting further doubt on the clinical relevance of pullout testing.     

Biomechanical efficacy of monoaxial or polyaxial pedicle screw and additional screw insertion at the level of fracture, in lumbar burst fracture: An experimental study

Background:

Use of a pedicle screw at the level of fracture, also known as an intermediate screw, has been shown to improve clinical results in managing lumbar fracture, but there is a paucity of biomechanical studies to support the claim. The aim of this study was to evaluate the effect of adding intermediate pedicle screws at the level of a fracture on the stiffness of a short-segment pedicle fixation using monoaxial or polyaxial screws and to compare the strength of monoaxial and polyaxial screws in the calf spine fracture model.

Materials and Methods:

Flexibility of 12 fresh-frozen calf lumbar spine specimens was evaluated in all planes. An unstable burst fracture model was created at the level of L3 by the pre-injury and dropped-mass technique. The specimens were randomly divided into monoaxial pedicle screw (MPS) and polyaxial pedicle screw (PPS) groups. Flexibility was retested without and with intermediate screws (MPSi and PPSi) placed at the level of fracture in addition to standard screws placed at L2 and L4.

Results:

The addition of intermediate screws significantly increased the stability of the constructs, as measured by a decreased range of motion (ROM) in flexion, extension, and lateral bending in both MPS and PPS groups (P < 0.05). There was neither any significant difference in the ROM in the spines of the two groups before injury, nor a difference in the ROM between the MPSi and PPSi groups (P > 0.05), but there was a significant difference between MPS and PPS in flexion and extension in the short-segment fixation group (P < 0.05).

Conclusions:

The addition of intermediate screws at the level of a burst fracture significantly increased the stability of short-segment pedicle screw fixation in both the MPS and PPS groups. However, in short-segment fixation group, monoaxial pedicle screw exhibited more stability in flexion and extension than the polyaxial pedicle screw.     

Morphometry of the lower thoracic and lumbar pedicles and its relevance in pedicle fixation

Purpose

To assess the pedicle morphology in the lower thoracic and lumbar spine in an Indian population and to determine the causes of pedicle wall violation by pedicle screws.

Methods

Computerised tomographic scans of 135 consecutive patients with thoracolumbar and lumbar spine fractures were prospectively analysed to determine the pedicle morphology. The transverse pedicle angle, pedicle diameter and screw path length at 527 uninjured levels were measured. Post-operative CT scans of 117 patients were analysed to determine the accuracy of 468 pedicle screws at 234 vertebrae.

Results

The lowest (mean ± SD) transverse pedicle width in the lower thoracic spine was 5.4 ± 0.70 mm, whereas in the lumbar spine it was 7.2 ± 0.87 mm. The shortest (mean ± SD) screw path length in lower thoracic pedicles was 35.8 ± 2.10 and 41.9 ± 2.18 mm in the lumbar spine. The mean transverse pedicle angle in the lower thoracic spine was consistently less than 5°, whereas it gradually increased from L1 through L5 from 8.5° to 30°. Forty-one screws violated the pedicle wall, due to erroneous angle of screw insertion.

Conclusions

In the current study, pedicle dimensions were smaller compared to the Western population. In Indian patients, pedicle screws of 5 mm diameter and 30 mm length, and 6 mm diameter and 35 mm length can safely be used in the lower thoracic and lumbar spine, respectively. However, it is important to assess the pedicle morphology on imaging prior to pedicle fixation.

     

The use of beta-tricalcium phosphate and bone marrow aspirate as a bone graft substitute in posterior lumbar interbody fusion

Purpose

Due to the disadvantages of iliac crest bone and the poor bone quality of autograft gained from decompression surgery, alternative filling materials for posterior lumbar interbody fusion cages have been developed. β-Tricalcium phosphate is widely used in cages. However, data regarding the fusion rate of β-TCP assessed by computer tomography are currently not available.

Materials

A prospective clinical trial involving 34 patients (56.7 years) was performed: 26 patients were treated with single-level, five patients double-level and three patients triple-level PLIF filled with β-TCP and bone marrow aspirate perfusion, and additional posterior pedicle screw fixation. Fusion was assessed by CT and X-rays 1 year after surgery using a validated fusion scale published previously. Functional status was evaluated with the visual analogue scale and the Oswestry Disability Index before and 1 year after surgery.

Results

Forty-five levels in 34 patients were evaluated by CT and X-ray with a follow-up period of at least 1 year. Clinically, the average ODI and VAS for leg and back scores improved significantly (P < 0.001). CT assessment revealed solid fusion in 12 levels (26.67 %) and indeterminate fusion in 15 levels (34.09 %). Inadequate fusion (non-union) was detected in 17 levels (38.63 %).

Conclusion

The technique of PLIF using β-TCP yielded a good clinical outcome 1 year after surgery, however, a high rate of pseudoarthrosis was found in this series therefore, we do not recommend β-TCP as a bone graft substitute using the PLIF technique.     

Single segment of posterior lumbar interbody fusion for adult isthmic spondylolisthesis: reduction or fusion in situ

Objective

We prospectively compared surgical reduction or fusion in situ with posterior lumbar interbody fusion (PLIF) for adult isthmic spondylolisthesis in terms of surgical invasiveness, clinical and radiographical outcomes, and complications.

Methods

From January 2006 to June 2008, 88 adult patients with isthmic spondylolisthesis who underwent surgical treatment in our unit were randomized to reduced group (group 1, n = 45) and in situ group (group 2, n = 43), and followed up for average 32.5 months (range 24–54 months). The clinical and radiographical outcomes were compared between the two groups.

Results

The average operative time and blood loss during surgery showed insignificant difference (p > 0.05) between two groups. The radiological outcomes were significantly better in group 1, but there was no significant difference between two groups of clinical outcomes, depicting as VAS, ODI, JOA and patients’ satisfaction surveys. Incident rate of surgical complications was similar in two groups, but in group 1 the complication seemed more severe because of two patients with neurological symptoms.

Conclusions

For the adult isthmic spondylolisthesis without degenerative disease in adjacent level, single segment of PLIF with pedicle screw fixation is an effective and safe surgical procedure regardless of whether additional reduction had been conducted or not. Better radiological outcome does not mean better clinical outcome.     

Posterior lumbar interbody fusion and segmental lumbar lordosis

Introduction

The sagittal plane of body produces a convex curve anteriorly referred to as the lordotic curve. Malalignment of lordotic curve leads to low back disorders and lumbar spinal surgery has been known to cause this. This study was a retrospective analysis of the effects of posterior lumbar interbody fusion using cages on segmental lumbar lordosis.

Materials and methods

We conducted a retrospective study involving 27 patients of which 16 were females and 11 were males. All patients underwent single level posterior lumbar interbody fusion with insertion of non-wedged intervertebral cage and pedicle screw fixation. Intraoperatively, all patients had a change from knee chest position to prone to augment their lumbar lordosis. The minimum follow up was 2 years and fusion was achieved in 21 patients.

Results

Segmental lordotic angles increased from 15.2° to 20.6° at L4/5 level and from 17.8° to 24.5° at L5/S1 level, preoperative to postoperative, respectively (P < 0.01 at both levels).

Conclusion

Thus apparently, posterior lumbar interbody fusion with insertion of non-wedged intervertebral cage and pedicle screw fixation results in creation and maintenance of lumbar lordosis.     

Comparison of unilateral versus bilateral pedicle screw fixation in lumbar interbody fusion: a meta-analysis

Purpose

This is a meta-analysis to compare the clinical results between unilateral and bilateral pedicle screw (PS) fixation in lumbar interbody fusion.

Methods

We included published studies with no language and year restrictions. The criteria which Koes et al. designed in 1995 were used to evaluate the risk of bias of the included studies. All data were analyzed by Review Manager 5.1. The primary outcomes included fusion rate and screw complications, and the secondary outcomes were operative time, blood loss, and hospital time.

Results

A total of five prospective studies with 407 patients were included in the current meta-analysis, and four of them were randomized controlled trials. There was no significant difference between unilateral PS fixation and bilateral PS fixation group in fusion rate and screw complications (fusion rate: OR 0.54, Z = 1.33, P = 0.18, I ² = 0 %; screw complications: OR 1.45, Z = 0.71, P = 0.48; I ² = 44 %). In the secondary outcomes, the operative time (Z = 3.35, P = 0.0008; I ² = 95 %) and blood loss (Z = 4.35, P < 0.0001; I ² = 98 %) was significantly higher in bilateral PS fixation group than in unilateral PS fixation group. Besides, no significant difference was found in hospital time (Z = 1.19, P = 0.24; I ² = 99 %).

Conclusions

In our meta-analysis, we found that unilateral PS fixation in lumbar fusion was as effective as bilateral PS fixation for lumbar degenerative diseases without major instability, no significant difference was found in hospital time, fusion rate and screw complications. In terms of operative time and blood loss, unilateral PS fixation even produced better results.     

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.     

Effect of osteoporosis on the clinical and radiological outcomes following one-level posterior lumbar interbody fusion

Background

Cage subsidence or pedicle screw loosening following lumbar fusion surgery is frequently reported in osteoporotic patients. However, few studies have analyzed clinical as well as radiological outcomes after such surgeries as a function of bone mineral density. We aimed to evaluate the impact of osteoporosis on the clinical and radiological outcomes of patients who underwent one-level posterior lumbar interbody fusion (PLIF).

X-Ray assessment of the effect of pedicle screw on vertebra and spinal canal growth in children before the age of 7 years

Purpose

To determine the reliability of pedicle screws placed in children younger than 7 years of age, and to evaluate the effect of pedicle screw insertion on further growth of the vertebra and spinal canal.

Methods

A retrospective study of 35 consecutive patients through Jan 2003–Dec 2010 for congenital scoliosis in <7 years children was performed at one spine center. Patients undergoing pedicle screw instrumentation of at least two levels, which had been followed-up for at least 24 months were included. Measurements were performed in instrumented and adjacent non-instrumented levels. The effect of pedicle screw insertion on further growth was evaluated.

Results

The average age at surgery was 4.4 year (53 months, range, 23–84 months). 190 segments in 35 patients met the inclusion criteria. 77 segments had no screws and 113 had at least one screw. There was a significant difference between the pre-operative and final follow-up values of the measurement of spinal canal and vertebral body parameters (P < 0.001). No significant difference existed between growth rates of vertebral bodies and the sagittal diameters of spinal canal with or without screws. The growth rates of vertebral bodies in lumbar spine were higher than in thoracic spine in both instrumented and adjacent groups.

Conclusion

Pedicle screw instrumentation does not cause a retardation effect on the development of vertebral bodies and the spinal canal in children at an early age. It is a safe and reliable procedure to achieve a stable fixation.     

Unilateral versus bilateral fixation for lumbar spinal fusion: a systemic review and meta-analysis

Purpose

The objective of this study was to systematically compare the efficacy and safety of unilateral fixation to bilateral fixation for the lumbar degenerative disease.

Study design

Systematic review and meta-analysis.

Methods

We searched databases including PubMed Central, MEDLINE (from 1966), EMBASE (from 1980), and Cochrane Central Register of Controlled Trials databases for randomized controlled trials or non-randomized controlled trials that compare unilateral fixation with bilateral fixation for the treatment for lumbar disease. Exclusion criteria were non-controlled studies, follow-up <6 months, combined anterior and posterior surgery, lumbar tumors, and non-English writing paper. Methodologic quality was assessed, relevant data were retrieved, and the appropriate meta-analysis was performed. Two review authors independently selected studies, extracted data, and assessed the risk of bias. The main end points included the rate of fusion, visual analogue scale (VAS), Oswestry disability index (ODI), intra-operative blood loss, operating time, and the rate of complications.

Results

A total of seven studies were included in the meta-analysis. Four relevant randomized controlled trials, one prospective study, and two retrospective studies involving 499 patients were identified. Patients in unilateral pedicle fixation group compared with bilateral pedicle screw fixation group on the fusion rate, VAS, ODI scores, and complication rate demonstrated no significant differences (P > 0.05, respectively). However, intra-operative blood loss and operating time in unilateral fixation group were significantly less than bilateral fixation group (P < 0.0001, respectively).

Conclusions

Unilateral fixation seems to be an effective, feasible, and safe procedure in one or two segmental disease when compare with bilateral instrumentation.     

Mid-term results of computer-assisted cervical reconstruction for rheumatoid cervical spines

Study design

A retrospective single-center study.

Summary and background

We routinely have used C1–C2 transarticular and cervical pedicle screw fixations to reconstruct highly destructed unstable rheumatoid arthritis (RA) cervical lesions. However, there is little data on mid-term results of surgical reconstruction for rheumatoid cervical disorders, particularly, cervical pedicle screw fixation.

Objectives

The purpose of this study was to evaluate the mid-term surgical results of computer-assisted cervical reconstruction for such lesions.

Methods

Seventeen subjects (4 men, 13 women; mean age, 61 ± 9 years) with RA cervical lesions who underwent C1–C2 transarticular screw fixation or occipitocervical fixation, with at least 5 years follow-up were studied. A frameless, stereotactic, optoelectronic, CT-based image-guidance system, was used for correct screw placement. Variables including the Japanese Orthopaedic Association (JOA) score, Ranawat class, EuroQol (EQ-5D), atlantodental interval, and Ranawat values before, and at 2 and 5 years after surgery, were evaluated. Furthermore, screw perforation rates were evaluated.

Results

The lesions included atlantoaxial subluxation (AAS, n = 6), AAS + vertical subluxation (VS, n = 7), and AAS + VS + subaxial subluxation (n = 4). There was significant neurological improvement at 2 years after surgery, as evidenced by the JOA scores, Ranawat class, and the EQ-5D utility weight. However, at 5 years after surgery, there was a deterioration of this improvement. The Ranawat values before, and at 2 and 5 years after surgery, were not significantly different. Major screw perforation rate was 2.1 %. No neural and vascular complications associated with screw insertion were observed.

Conclusions

Subjects with rheumatoid cervical lesions who underwent C1–C2 transarticular screw fixation or occipitocervical fixation using a pedicle screw had significantly improved clinical parameters at 2 years after surgery. However, there was a deterioration of this improvement at 5 years post surgery.     

Coflex内固定术与PLIF术治疗腰椎管狭窄症的疗效对比

[目的]探讨采用Coflex棘突间动态内同定植入术与传统PLIF术治疗单节段腰椎管狭窄症的疗效并进行对比研究.[方法]术前准确定位手术减压节段后分别采用腰后路减压Coflex棘突间动态内固定植入术(Coflex组)及腰后路减压植骨融合内固定术(PLIF组)治疗单节段腰椎管狭窄症72例,观察两组手术时间、出血量及并发症的差异;术前、术后随访时分别采用VAS评分和ODI进行相关功能评价;通过影像学观察手术节段及上邻节段术前、术后屈伸活动度变化.[结果]两组患者术后VAS、ODI评分均较术前明显下降(P<0.01),术后功能恢复无明显差异(P>0.05),而Coflex组手术时间、出血量均较传统PLIF组减少(P<0.01);术后1年Coflex组手术节段活动度与术前相比减少(P<0.05),PLIF组上邻椎间运动幅度组较术前增加(P<0.05),而Coflex组稍减少,与术前相比无明显差异(P>0.05).[结论]Coflex棘突间内固定技术治疗单节段腰椎管狭窄症疗效好,并且具有手术时间短,出血量小,能保留手术节段一定的活动度,对上邻节段活动度影响小等优点.     

Biomechanical comparison of sagittal-parallel versus non-parallel pedicle screw placement

Background

While convergent placement of pedicle screws in the axial plane is known to be more advantageous biomechanically, surgeons intuitively aim toward a parallel placement of screws in the sagittal plane. It is however not clear whether parallel placement of screws in the sagittal plane is biomechanically superior to a non-parallel construct. The hypothesis of this study is that sagittal non-parallel pedicle screws do not have an inferior initial pull-out strength compared to parallel placed screws.

Methods

The established lumbar calf spine model was used for determination of pull-out strength in parallel and non-parallel intersegmental pedicle screw constructs. Each of six lumbar calf spines (L1-L6) was divided into three levels: L1/L2, L3/L4 and L5/L6. Each segment was randomly instrumented with pedicle screws (6/45 mm) with either the standard technique of sagittal parallel or non-parallel screw placement, respectively, under fluoroscopic control. CT was used to verify the intrapedicular positioning of all screws. The maximum pull-out forces and type of failure were registered and compared between the groups.

Results

The pull-out forces were 5,394 N (range 4,221 N to 8,342 N) for the sagittal non-parallel screws and 5,263 N (range 3,589 N to 7,554 N) for the sagittal-parallel screws (p?=?0.838). Interlevel comparisons also showed no statistically significant differences between the groups with no relevant difference in failure mode.

Conclusion

Non-parallel pedicle screws in the sagittal plane have at least equal initial fixation strength compared to parallel pedicle screws in the setting of the here performed cadaveric calf spine experiments.     

Prospective comparative study between straight and curved probe for pedicle screw insertion

Purpose

To evaluate difference in accuracy of pedicle screw insertion in thoracic and lumbosacral spine using a straight pedicle probe vis-à-vis a curved one.

Methods

Prospective, comparative, non-randomized, single-blind study. Straight and curved pedicle probes used on opposite sides of same vertebra in patients undergoing thoracolumbar pedicle screw fixation for various indications. Postoperative blinded evaluation for pedicle breaches done with a CT scan. Pedicle breaches graded as grade 0: no breach, grade 1: <2 mm, grade 2: 2–4 mm and grade 3: >4 mm breach.

Results

After appropriate statistical power analysis, 300 screws inserted in 59 patients from T4–L5 levels. No significant differences noted between the two probes in terms of screw length [two-tailed p = 0.16]; grade 0 screws [two-tailed p = 0.49] or screws with grade 2/3 breaches [two-tailed  p = 0.68]. With the right-hand-dominant operating-surgeon standing to left of patient during surgery, no difference noted between the two probes for either the right or left-side pedicle screw insertion [two-tailed p = 1]. Repeating these tests in the subset of thoracic pedicle screws too, revealed no significant difference.

Conclusions

No significant difference in outcome of pedicle screw insertion with either a straight or a curved pedicle probe.     

Interspinous spacers versus posterior lumbar interbody fusion for degenerative lumbar spinal diseases: a meta-analysis of prospective studies

Purpose

Our aim is to evaluate the safety and effectiveness of interspinous spacers versus posterior lumbar interbody fusion (PLIF) for degenerative lumbar spinal diseases.

Methods

A comprehensive literature search was performed using PubMed, Web of Science and Cochrane Library through September 2015. Included studies were performed according to eligibility criteria. Data of complication rate, post-operative back visual analogue scale (VAS) score, Oswestry Disability Index (ODI) score, estimated blood loss (EBL), operative time, length of hospital stay (LOS), range of motion (ROM) at the surgical, proximal and distal segments were extracted and analyzed.

Results

Ten studies were selected from 177 citations. The pooled data demonstrated the interspinous spacers group had a lower estimated blood loss (weighted mean difference [WMD]: ?175.66 ml; 95 % confidence interval [CI], ?241.03 to ?110.30; p?<?0.00001), shorter operative time (WMD: ?55.47 min; 95%CI, ?74.29 to ?36.65; p?<?0.00001), larger range of motion (ROM) at the surgical segment (WMD: 3.97 degree; 95%CI, ?3.24 to ?1.91; p?<?0.00001) and more limited ROM at the proximal segment (WMD: ?2.58 degree; 95%CI, 2.48 to 5.47; p?<?0.00001) after operation. Post-operative back VAS score, ODI score, length of hospital stay, complication rate and ROM at the distal segment showed no difference between the two groups.

Conclusions

Our meta-analysis suggested that interspinous spacers appear to be a safe and effective alternative to PLIF for selective patients with degenerative lumbar spinal diseases. However, more randomized controlled trials (RCT) are still needed to further confirm our results.

     

Tranexamic acid reduces postoperative blood loss of degenerative lumbar instability with stenosis in posterior approach lumbar surgery: a randomized controlled trial

Study design

This study is randomized controlled trial.

Purpose

To evaluate the effect of tranexamic acid (TXA) on reducing postoperative blood loss in posterior approach lumbar surgery for degenerative lumbar instability with stenosis.

Methods

Sixty patients with degenerative lumbar instability with stenosis were randomized into TXA and control groups, receiving 15 mg/kg body weight of TXA or placebo (0.9 % Sodium chloride solution) intravenously, respectively, before the skin incision was made. The operation of pedicle screw system fixation was performed for all patients, and then selective laminectomy and posterior lumbar interbody fusion (PLIF) were carried out. Intraoperative and postoperative blood loss were compared between the two groups. And the complication of TXA was also investigated.

Results

There were no statistically significant differences between the TXA and control groups in terms of age, sex, body mass index, and operation time. There was no significantly difference in intraoperative blood loss between the two groups. However, in the TXA group, postoperative blood loss was significantly lower than that in the control group (13.0 %). Especially, postoperative blood loss during the first 12 h was reduced by 29.9 % as compared to the control group. There were no thromboembolic events or other complications occurred in either group.

Conclusions

Preoperative single-dose TXA can significantly reduce postoperative blood loss in posterior approach lumbar surgery, and there were no significant side effects.