Posterior Disc Height Research Articles

Interbody Fusion in Low Grade Lumbar Spondylolsithesis: Clinical Outcome Does Not Correalte with Slip Reduction and Neural Foraminal Dimension.

Study DesignProspective nonrandomized study.PurposeTo find a possible correlation between clinical outcome and extent of lumbar spondylolisthesis reduction.Overview of LiteratureThere is no consensus in the literature concerning whether a beneficial effect of reduction on outcome can be expected following reduction and surgical fusion for low grade lumbar spondylolisthesis.MethodsForty six patients with a mean age of 37.5 years (age, 17–48 years) with isthmic spondylolisthesis underwent interbody fusion with cages with posterior instrumentation (TLIF). Clinical outcome was measured using visual analogue score (VAS) and Oswestry disability index (ODI). Foraminal dimensions and disc heights were measured in standard digital radiographs. These were analyzed at baseline and 1 year after surgery and changes were compared. Radiographic fusion was judged with computed tomography scans at 1 year.ResultsNinety percent of the patients had good or very good clinical results with fusion and instrumentation. Baseline and one-year postoperative mean VAS score was 6.33 (range, 5–8) and 0.76 (range, 0–3), respectively (p=0.004). Baseline and one-year postoperative, mean ODI score was 48 (range, 32–62) and 10 (range, 6–16), respectively (p<0.001). A mean spondylolisthesis slip of 32.1% was reduced to 6.7% at 1 year. Average anterior disc height, posterior disc height, vertical foraminal dimension), and foraminal) diameter improved from 9.8 to 11.7 mm (p=0.005), 4.5 to 5.8 mm (p=0.004), 11.3 to 12.6 mm (p=0.002), and 18.6 to 20.0 mm (p<0.001), respectively. The fusion rate was 75% with TLIF. There is no significant correlation between the improvements of ODI scores and the extent of slip reduction.ConclusionsNeural decompression and interbody fusion can significantly improve pain and disability but the clinical outcome does not correlate with radiological improvement in the neural foraminal dimension.

Adjacent disc height reduction and clinical outcome after intradiscal cement leakage.

The purpose of this study is to evaluate the effect of intradiscal cement leakage on the height of adjacent cement-containing discs and the resulting clinical efficacy after kyphoplasty. A total of 124 patients were included and classified into two groups: group A included 20 patients with intradiscal leakage, and group B contained 104 patients without intradiscal leakage. The mean follow-up time was 20.56±3.51 months. The height of the corresponding discs in both groups was measured using Farfan's method. Clinical efficacy was assessed using the Visual Analog Scale and Oswestry Disability Index scores at each follow-up time. The anterior disc height, posterior disc height and Farfan Index significantly decreased in both groups at last follow-up. The disc height reduction was 9.19±2.89% in group A and 3.88±2.70% in group B, which was significantly different between the groups (P<0.01). The disc height reduction rate was 29.39±7.90% in group A and 12.75±8.18% in group B, which was also a statistically significant difference (P<0.01). The VAS and ODI scores improved significantly after surgery and maintained at last follow-up, and there was no statistically significant difference between Groups A and B. Intradiscal cement leakage was associated with the degeneration of cement-containing disc but did not reduce the clinical efficacy at early stages.

Preoperative Segmental Disc Geometry as a Possible Predictor fo r the Clinical Outcome of Lumbosacral Total Disc Replacement

Total disc replacement has been developed as an alternative to fusion. However, several factors are associated with an inferior clinical mid-term outcome. There is a need for simple but well-defined preoperative factors, which have a predictive value and facilitate patient selection for lumbosacral total disc replacement (TDR). Therefore, in the present study we investigated preoperative radiological parameters to serve as predictors for the clinical outcome after TDR at the lumbosacral junction. A total of 34 patients (16 females, 18 males) with the primary diagnosis of lumbosacral degenerative disc diseases who underwent TDR between 08/2005 and 12/2010 were evaluated in a clinical examination (Oswestry Disability Questionnaire (ODI) and visual analog scale (VAS) for overall, back, and leg pain) after a mean follow-up of 59.5 (24–87) months. A correlation analysis was performed between preoperative radiological parameters (segmental lordosis (SL), mean disc height (meanDH), anterior (aDH), middle (mDH), and posterior disc height (pDH) as well as geometrical relationships of these parameters: nA Index=aDH/meanDH, nP-Index=pDH/meanDH, AP-Index=aDH/ pDH, and nAP Index=aDH/pDH/meanDH) and clinical pain scales (ODI, VAS) at follow-up. Particularly the relationships nA-Index, AP-Index, and nAP-Index were found to be strongly negatively correlated to the clinical outcome. Weaker correlation was found between: ODI and aDH, nA-Index, AP-Index (negative), and nP-Index (positive); VAS overall and SL, nP Index, mDH, and pDH (positive); and VAS back and nP-Index, and pDH (positive). The preoperative normalized anterior-disc-height-index (nA Index) and the normalized anterior-posterior-discheight- index (nAP-Index) can serve as prognostic radiographic parameters before patients undergo lumbosacral TDR.

Effect of single-level Discover cervical artificial disc replacement on cervical sagittal alignment

Objective To evaluate the effect of single-level Discover cervical artificial disc replacement on cervical sagittal alignment. Methods Retrospective analysis was conducted on patients who underwent single-level Discover cervical artificial disc replacement in our hospital from February 2012 to September 2014. Sixty-two patients (34 males, 28 females) with an average age of 45.2±8.2 (31-61) who were diagnosed with single-level cervical disc herniation were included (C3-4 3 cases, C4-5 12 cases, C5-6 34 cases, C6-7 13 cases). We measured the cervical sagittal alignment parameters: index level disc angle, functional spinal unit (FSU) angle, C2-C7 angle, anterior disc height (ADH), middle disc height (MDH), posterior disc height (PDH), anterior FSU height (AFH), middle FSU height (MFH), posterior FSU height (PFH) on neutral lateral radiographs before surgery and 3 months after surgery. Results All of the patients were followed up for 3 months. The cervical sagittal alignment parameters before surgery and 3 months after surgery were as follows. Index level disc angle increased from 0.0°±4.2° to 7.3°±3.9°, FSU angle increased from 2.3°±5.0° to 6.9°±4.8°, C2-C7 angle increased from 9.5°±10.8° to 13.1°±9.1°, ADH increased from 4.3±1.0 mm to 7.9±1.1 mm, MDH increased from 5.8±0.9 mm to 8.1±0.9 mm, PDH increased from 3.7±0.9 mm to 5.5±0.9 mm, AFH increased from 34.1±3.5 mm to 36.2±3.4 mm, MFH increased from 32.3±3.5 mm to 33.6±3.3 mm, PFH increased from 33.9±3.5 mm to 34.6±3.2 mm. All changes were statistically significant (P<0.05). Conclusion Single-level Discover cervical artificial disc replacement can improve the disk angle, FSU angle, and disk height effectively in early follow-up period, thereby improving the cervical sagittal alignment. Key words: Cervical vertebrae; Total disc replacement; Treatment outcome

Choice of Approach Does Not Affect Clinical and Radiologic Outcomes: A Comparative Cohort of Patients Having Anterior Lumbar Interbody Fusion and Patients Having Lateral Lumbar Interbody Fusion at 24 Months.

Study Design Retrospective analysis of prospectively collected registry data.Objective This study aimed to compare the clinical and radiologic outcomes between comparative cohorts of patients having anterior lumbar interbody fusion (ALIF) and patients having lateral lumbar interbody fusion (LLIF).Methods Ninety consecutive patients were treated by a single surgeon with either ALIF (n = 50) or LLIF (n = 40). Inclusion criteria were patients age 45 to 70 years with degenerative disk disease or grade 1 to 2 spondylolisthesis and single-level pathology from L1 to S1. Patient-reported outcome measures included pain (visual analog scale), disability (Oswestry Disability Index [ODI]), and quality of life (Short Form 36 physical component score [PCS] and mental component scores [MCS]). Assessment of fusion and measurement of lordosis and posterior disk height were performed on computed tomography scans.Results At 24 months, patients having ALIF had significant improvements in back (64%) and leg (65%) pain and ODI (60%), PCS (44%), and MCS (26%; p < 0.05) scores. Patients having LLIF had significant improvements in back (56%) and leg (57%) pain and ODI (52%), PCS (48%), and MCS (12%; p < 0.05) scores. Fourteen complications occurred in the ALIF group, and in the LLIF group, there were 17 complications (p > 0.05). The fusion rate was 100% for ALIF and 95% for LLIF (p = 0.1948). ALIF added ∼6 degrees of lordosis and 3 mm of height, primarily measured at L5–S1, and LLIF added ∼3 degrees of lordosis and 2 mm of height between L1 to L5. Mean follow-up was 34.1 months.Conclusions In comparative cohorts of patients having ALIF and patients having LLIF at 24 months postoperatively, there were no significant differences in clinical outcomes, complication rates, or fusion rates.

Clinical Outcome and Changes of Foraminal Dimension in Patients With Foraminal Stenosis After ACDF.

Prospective study. To determine the clinical outcome and change in foraminal dimension after anterior cervical discectomy and fusion (ACDF) and to investigate the correlation between clinical outcome and foraminal dimension. No previous studies have evaluated the correlation between clinical outcome and foraminal dimension after ACDF in foraminal stenosis. A consecutive series of 44 patients (114 foramina) undergoing planned ACDF due to foraminal stenosis were studied. Clinical outcomes included the neck pain visual analogue scale (VAS), arm pain VAS, neck disability index (NDI), subjective improvement rate, dysphasia, and donor site pain. Radiologic outcomes included anterior and posterior disk height, height of foramen and anterior-posterior diameter of the foramen, and the Cobb angle of the fusion segment. Foraminal dimension was calculated. The neck pain VAS decreased from 3.7 preoperatively to 2.3 postoperatively. Likewise, arm pain VAS decreased from 7.2 to 2.2, and NDI decreased from 31.0% to 17.2%. Mild dysphasia occurred in 3 patients. There was no donor site pain. Subjective improvement rate was 79.3%. The anterior disk height increased from 4.75 mm preoperatively to 7.01 mm postoperatively. Likewise, posterior disk height increased from 4.11 to 5.74 mm, height of foramen increased from 7.30 to 9.25 mm, anterior-posterior diameter of foramen increased from 3.56 to 4.92 mm, dimension of foramen increased from 20.50 to 35.58 mm, and segmental angle of fusion segment increased from 2.87 to 4.95 degrees. Posterior disk height was positively correlated with foraminal dimension. An increased segmental angle was negatively correlated with foraminal dimension. The foraminal dimension was negatively correlated with the arm pain VAS. ACDF in cervical foraminal stenosis was a useful surgical option to improve clinical outcomes and widen the foraminal dimension. The foraminal dimension was negatively correlated with the arm pain. Restoration of posterior disk height was necessary to widen the foraminal dimension, whereas increased lordosis of the fusion segment did not help to widen the foraminal dimension.

Paradoxical Radiographic Changes of Coflex Interspinous Device with Minimum 2-Year Follow-Up in Lumbar Spinal Stenosis

Studies have yet to investigate long-term radiologic changes in lumbar spinal stenosis patients treated with interspinous device (Coflex). This study aimed to evaluate which radiologic parameters change significantly after surgery with Coflex and identify which parameter most affects the radiologic outcome. Of 101 patients with lumbar spinal stenosis treated by Coflex insertion on L4-5, the radiologic parameters of 30 patients were measured before and at least 2 years after surgery. On the basis of the development of bony erosion around Coflex, patients were divided into the erosion group (n = 14) or the nonerosion group (n = 16). The mean anterior disc height (ADH) and range of motion (ROM) were significantly decreased after surgery (15.161 mm vs. 13.788 mm and 9.63° vs. 7.13°). The erosion group showed substantially higher values in preoperative ADH, postoperative posterior disc height (PDH), and intervertebral foramen height (6.52 mm vs. 8.05 mm; 5.80 mm vs. 8.03 mm; 19.20 mm vs. 21.06 mm). Postoperative ROM and ROM ratio were higher in the erosion group (5.95° vs. 8.47° and 0.659 vs. 0.938). However, only ADH showed a significant change in the erosion group after surgery (15.86 mm vs. 14.29 mm). On the contrary, ADH and PDH, as well as ROM, were significantly decreased in the nonerosion group (14.55 mm vs. 13.34 mm; 6.52 mm vs. 5.82 mm; 9.46° vs. 5.95°). The preoperative state including relatively higher ADH, PDH, and larger ROM could induce erosion. The long-term preservation of disc height and ROM may also induce erosion. That reduction of most radiologic parameters seems to be natural after surgery, and insufficient reduction of disc height and ROM may induce adverse effects, which can increase the possibility of spinous process fracture or device malposition.

Stand-alone anterior lumbar interbody fusion for treatment of degenerative spondylolisthesis

We sought to evaluate the clinical and radiologic efficacy of stand-alone anterior lumbar interbody fusion (ALIF) for low grade degenerative spondylolisthesis, the favoured surgical management approach at our institution. The optimal approach for surgical management of spondylolisthesis remains contentious. We performed a prospective analysis of all consecutive patients with low grade lumbar spondylolisthesis who underwent ALIF between 2009 and 2013 by a single surgeon (n=27). The mean age was 64.9years with a male to female ratio of 14:13. There were 32 levels operated and the average preoperative spondylolisthesis was 14.8%, which reduced to 6.4% postoperatively and 9.4% at the latest follow-up (p=0001). Postoperative disc height was increased to 175% of preoperative values and was statistically significant (p<0.001) and remained improved with an overall change of 139% at the latest follow-up. The radiological fusion rate was 91%. The 12-Item Short Form Health Survey (SF-12) mental and physical component summary improved from 31.7 to 43.0 (p=0.007) and from 35.4 to 51.7 (p=0.0026), respectively. The mean visual analogue scale pain score improved from 7.6 to 2.2 (p<0.001), and the mean Oswestry disability index improved from 56.9 to 17.8% (p<0.0001). The overall clinical success rate was 93%. The posterior disc height correlated with spondylolisthesis reduction (p=0.04) and the only clinical factor affecting reduction was body mass index (p=0.04). The present study provides encouraging short term results for stand-alone ALIF as a procedure for low grade lumbar degenerative spondylolisthesis. Future studies should include adequately powered, prospective, multicentre registry studies with long term follow-up to allow a better assessment of the relative benefits and risks.

Morphologic Changes in Contralateral Lumbar Foramen in Unilateral Cantilever Transforaminal Lumbar Interbody Fusion Using Kidney-type Intervertebral Spacers

A retrospective study of 58 patients undergoing cantilever transforaminal lumbar interbody fusion (c-TLIF). To evaluate morphologic changes in the intervertebral foramen (IVF) on the side contralateral to spacer insertion in patients undergoing c-TLIF using plain x-ray films and computed tomography scan. The morphologic changes in the contralateral lumbar foramen in c-TLIF using unilateral insertion of spacers have not been well studied. Fifty-eight consecutive patients with lumbar dysplastic changes or degenerative disk diseases underwent c-TLIF using 96 kidney-type spacers with local bone grafts. Radiographic findings (sagittal disk angle), computed tomography scan findings (coronal disk angle, disk height, foraminal height (FH), foraminal width, and cross-sectional area of IVF in contralateral lumbar foramen) were compared between preoperative period and 6 months after surgery. The correlations between contralateral lumbar foraminal dimensions and disk height, sagittal disk angle, and coronal disk angle were analyzed. After c-TLIF, sagittal angle, disk height, FH, foraminal width, and cross-sectional area of the IVF were significantly increased. Increase in posterior disk height showed a positive correlation with increases in FH, foraminal width, and cross-sectional area of IVF (r=0.235-0.511). However, the increase in sagittal disk angle showed a negative correlation with changes in foraminal width and cross-sectional area of IVF (r=-0.256 to -0.206). Lumbar foraminal dimensions on the side contralateral to spacer insertion increased significantly after c-TLIF, suggesting that c-TLIF enables indirect decompression of the contralateral nerve root. Although increase in posterior disk height was shown to be an important factor to increase contralateral foraminal size, segmental lordosis was a risk factor for a decrease in contralateral foraminal size.

Improvement in Disc Height after Lumbar Arthroplasty with Mobidisc and Minimum 3 Years of Follow-Up

Introduction Degenerative disc disease (DDD) is one of the most common reasons for low back pain in active population. During process of degeneration disc loose water content that leads diminishing of disc height. Disc degeneration is characterized by loosening of water content. These leads to diminishing of disc height, higher stress to facet joints and narrowing neural foramina. The aim of this study is to evaluate improvement in disc height after total lumbar arthroplasty at L4–L5 and L5–S1 segments with a Mobidisc prosthesis. Patients and Methods We analyzed 63 patients in which Mobidisc lumbar prosthesis were implanted at L4–L5 and L5–S1 segments during period of January 2008 to January 2011 in Civil Hospital in Strasbourg, France. Full standing X-rays have been done preoperatively and postoperatively after 6 weeks, 3, 6, 12, and 36 months. X-rays were digitalized and measurement were performed by using Spineview software. Measurement was statistically significance at p &lt; 0.05. Results The mean follow-up was 44 months; 45 females and 18 males were analyzed with average 41.3 year of age. Prosthesis was implanted at L4–L5 in 19 cases and at L5–S1 in 44 cases. Preoperative anterior disc height at L4–L5 was significantly improved, from 6.30 to 9.03 mm (2.73 mm) postoperatively ( p &lt; 0.01). Posterior disc height at same level was also improved, from 2.82 mm preoperatively to 3.90 mm postoperatively (1.08 mm) ( p &lt; 0.05). At level L5–S1 anterior and posterior disc height were improved as well. From 4.99 mm to 7.53 mm (2.54 mm) ( p &lt; 0.05) and from 2.52 mm to 4.66 mm (2.14 mm), respectively, ( p &lt; 0.05). Conclusion During lumbar disc arthroplasty the size of prosthesis may have a significant role in a final postoperative result. Oversize prosthesis may produce too much distraction to posterior ligaments and muscles of lumbar spine. On the other hand, too small implants will not reduce stress enough on facet joints nor will adequately open neural foramina. In both cases, this would probably result in painful syndromes of lumbar spine.

Comparison of Allograft and Polyetheretherketone Cage in Anterior Cervical Discectomy and Fusion

Introduction Structural allografts and PEEK cages are commonly used as interbody fusion devices in ACDF. The subsidence rates of these two spacers have not yet been directly compared. The primary aim of this study was to compare the subsidence rate of allograft and PEEK cage in ACDF. The secondary aim was to determine if the presence of subsidence affects the clinical outcome. Methods We reviewed 67 cases (117 levels) of ACDF with either structural allograft or PEEK cages. There were 85 levels (48 cases) with PEEK and 32 levels (19 cases) with allograft spacers. All surgeries were performed by a fellowship-trained spine surgeon from November 2005 to September 2012. Immediate postoperative and 6-month lateral cervical radiographs were evaluated for subsidence by measuring the anterior disc height and posterior disc height at each operative level. Subsidence was defined as a decrease in anterior or posterior disc heights &gt; 1 mm. The subsidence rate between the two groups was compared using the chi-square to test for significance (α = 0.05). NDI was recorded to evaluate the clinical outcome of the subsidence (SG) and nonsubsidence groups (NSG). t-test was used to test for difference between the two groups (α = 0.05). Results There was no statistically significant difference between subsidence rate of the PEEK group (54%; 46/685) and the allograft group (59%; 19/32) ( p = 0.69). Overall mean subsidence was 1.0 ± 1.3 mm anteriorly and 1.2 ± 1.2 mm posteriorly. The mean NDI improvement was 11.7 (from 47.1 to 35.4; average follow-up: 12 months) for the SG and 14.0 (from 45.8 to 31.8; average follow-up: 13 months) for the NSG ( p = 0.74). Conclusion The subsidence rate does not seem to be affected by the use of either PEEK or allograft as spacers in ACDF. Furthermore, subsidence alone does not seem to be predictive of clinical outcomes of ACDF.

Surgical Treatment of Lumbar Degenerative Problems with CD HORIZON BalanC Spinal System

Introduction Adjacent segment degeneration (ASD) is a common (34%) problem following posterior spinal fusions which may deteriorate functional outcomes in long-term follow-up. CD HORIZON BalanC rod has a dynamic portion made of silicone and polyetheretherketone (PEEK) aiming motion preservation, and fusion portion is entirely made of PEEK. The aim of this study is to evaluate the efficacy of CD HORIZON BalanC Spinal System in the treatment of multilevel lumbar degenerative disease and to identify fusion and ASD rates with MRI and 3D CT scan for both adjacent (AL) and dynamic (DL) levels with clinical outcomes. Patients and Methods A total of 30 patients (18 F and 12 M) mean age 47.3 years (range, 26–65 years) with 50 levels of TLIF with more than 2-year follow-up were reviewed. TLIF were single level in 12 patients, 2 levels in 16 patients and 3 levels in 2 patients. Pre-op, post-op AP/L X-rays were measured for pelvic and sagittal parameters. Disc angles, ROM, anterior disc height (ADH), and posterior disc height (PDH) were measured for AL and DL. Disc and facet degenerations for AL and DL were evaluated with MRI and 3D CT scan at the end of 2-year follow-up. Clinical evaluation was done with ODI and VAS. Results Mean follow-up was 26.3 months (range, 24–38 months). Av instrumented levels was 3.33 (range, 2–5) and av. fused levels was 1.66 (range, 1–3). TLIF were at L5–S1 in 23 patients, L4–L5 in 20 patients, L3–L4 in 6 patients, and L2–L3 in 1 patient. Pre-op LL was restored to 42.7 and 49.3 degrees. There were no significant differences in ADH, PDH, and disc angles between pre-op and follow-up for AL and DL ( p &gt; 0.05). Pre-op AL av. ROM of 5.85 degrees changed to 6.57 degrees. Pre-op DL av. ROM of 6.72 degrees was decreased to 5.07 degrees with a limitation of 24.6% post-op. There were no significant changes in terms of disc and facet degeneration grades for both AL and DL at final follow-up ( p &gt; 0.05). 3D CT evaluation revealed solid fusions for all TLIF levels. Mean of 43.51% ODI was improved to 18.93 and pre-op VAS score 7.2 was improved to 2.2. Conclusion In lumbar spinal fusion surgeries performed with CD HORIZON BalanC Spinal system, MRI and 3D CT scan studies at the end of 2-year follow-up did not show any significant deterioration in terms of disc and facet degeneration for AL and DL. Dynamic portion of the rod limits ROM by 24.6% at dynamic level. Dynamic portion seems to be effective in preventing ASD at the end of 2-year follow-up.

Comparison of Subsidence Rates of Large and Small Footprint Cages in Anterior Cervical Interbody Fusion

Introduction Subsidence rates after ACDF have been reported widely in literature and range from 0 to 57%. Polyetheretherketone (PEEK) cages are one of the most commonly used interbody spacers. Although subsidence rates of different types of cages have been described, there are still no data on the effect of cage footprint size on subsidence. The primary aim of this study was to compare the subsidence rate between small and large footprint polyetheretherketone (PEEK) cages. The secondary aim was to determine if a correlation exists between subsidence and health outcome scores. Methods We performed a retrospective medical chart and radiographic review. Two fellowship-trained spine surgeons performed the surgeries from November 2008 to January 2013. Immediate postoperative and 6-month lateral cervical radiographs were evaluated for subsidence. Anterior and posterior disc heights at each operative level were measured. Subsidence was defined as a decrease in anterior or posterior disc height of &gt; 1 mm. Cases were then designated to either the subsidence group (SG) or nonsubsidence group (NSG). Small footprint cage group (SF) consisted of PEEK cages measuring 14 × 11, 14 × 12, or 12.5 × 11.5 mm. Large footprint cage group (LF) consisted of cages measuring 15 × 13, 16 × 14, or 18 × 16 mm. Subsidence rates of the SF and LF groups were compared using chi-square test (α = 0.05). Preoperative and final (minimum 6 months) postoperative Neck Disability Index (NDI) scores of the SG and NSG were compared using t-test (α = 0.05). Results We reviewed 140 levels (71 cases*) of ACDF using small and large footprint PEEK cages. The small footprint group had 45 cases* (79 levels) and the small footprint group had 27 cases* (61 levels) with large footprint cages (* one case had both large and small footprint cages implanted on different levels) . There was a statistically significant difference between the subsidence rates of SF (54%; 43/79) and LF (30%; 18/61) ( p = 0.003). Fig. 1 breaks down the subsidence rate by cage size. Overall mean subsidence (SG) was 1.6 ± 1.1 mm anteriorly and 1.9 ± 1.1 mm posteriorly. Mean NDI improvement was 8.8 ± 23.2 mm (average follow-up: 13 months) for the SG and 22.9 ± 18.8 (average follow-up: 13 months) for the NSG ( p = 0.01). Conclusion Use of large footprint cages seems to have a protective effect against subsidence. Furthermore, cage subsidence &gt; 1 mm results in less clinical improvement. [Figure: see text]

Standalone Anterior Lumbar Interbody Fusion for Spondylolisthesis

Introduction Debate continues over the optimal approach for fusion of isthmic and degenerative spondylolisthesis. We favor anterior lumbar interbody fusion (ALIF) as it permits liberal discectomy and placement of a large, lordotic device which restores disc height and sagittal balance, reduces listhesis, and indirectly decompresses exiting nerve roots. There are only a few articles in the literature looking at the degree of reduction and the durability over time in patients undergoing ALIF with spondylolisthesis. Material and Methods We studied the initial degree of reduction achieved, and the durability of this reduction over time when ALIF was used for patients with isthmic and degenerative spondylolisthesis. Analysis of prospectively collected radiographic data was conducted. All patients with lumbar spondylolisthesis who underwent standalone ALIF between 2009 and 2013 by a single surgeon (R. J. M.) were included. Radiological analysis of slip percentage and disc height on preoperative, postoperative, and latest follow-up imaging was performed with Surgimap Spine software. Demographic factors, surgical data and radiological results were compared. Results Average patient age was 64.5 years (range, 37–84) with 16 females, 15 males. There were 36 levels treated with 20 at L4/5, 15 at L5/S1, and one at L3/4. Mean listhesis was 16% which immediately postoperatively reduced to 2.3%, but at latest follow-up had recurred to 58% of the original value. An average disc height increase of 184% was observed postoperatively. Analysis of these measurements showed a high degree of inter- and intraclass correlation. Mean follow-up was 17 months. BMI correlated with immediate postoperative reduction ( p = 0.004), as did posterior disc height ( p = 0.04). The overall radiological fusion rate was 91%. Three patients required subsequent posterior instrumentation, which will be discussed. Conclusion ALIF achieves disc height restoration and indirect listhesis reduction in isthmic and degenerative spondylolisthesis. Although this reduction may regress over time, we found it remained reduced by approximately 50% at latest follow-up. Around 10% of patients required further strengthening by posterior pedicle screw fixation. Standalone ALIF without posterior pedicle screw fixation is successful in the majority of patients with spondylolisthesis.

Minimum 5 year follow-up of multi-segmental lumbar degenerative disease treated with discectomy and the Wallis interspinous device

We evaluate the clinical effects and radiological findings of the Wallis interspinous device (Zimmer, Warsaw, IN, USA) for the treatment of multi-segmental lumbar degenerative disease after a minimum 5year follow-up period. A total of 26 adult patients underwent a primary discectomy followed by fixation of the segment with the Wallis interspinous device between December 2007 and August 2008. Twelve men and 14 women with an age range of 43 to 56years (average: 47.6) were included. The visual analogue scale (VAS) for low back and leg pain, Oswestry Disability Index (ODI), foraminal height (FH), anterior disc height (aDH) and posterior disc height (pDH), range of motion (ROM) and Pfirrmann grades were obtained and compared before and after surgery. The VAS and ODI significantly decreased postoperatively (p<0.05). The postoperative FH and pDH values increased significantly compared with the preoperative levels (p<0.01) and the increase in the FH and pDH values remained statistically significant during the follow-up period. There were no statistically significant changes in the aDH values before and after surgery (p>0.05). Also, there were no statistically significant changes in the ROM and Pfirrmann grade at the instrumented level and at the cephalad-adjacent segment (p>0.05). In our study, no patient underwent further surgery because of a re-prolapse or progression of index level degeneration or adjacent segment disease. The Wallis interspinous device was a useful alternative for treating multi-segmental lumbar degenerative disease and it offered a significant minimum 5year symptom control.

CT morphometry of adult thoracic intervertebral discs.

Despite being commonly affected by degenerative disorders, there are few data on normal thoracic intervertebral disc dimensions. A morphometric analysis of adult thoracic intervertebral discs was, therefore, undertaken. Archival computed tomography scans of 128 recently deceased individuals (70 males, 58 females, 20-79 years) with no known spinal pathology were analysed to determine thoracic disc morphometry and variations with disc level, sex and age. Reliability was assessed by intraclass correlation coefficients (ICCs). Anterior and posterior intervertebral disc heights and axial dimensions were significantly greater in men (anterior disc height 4.0±1.4 vs 3.6±1.3 mm; posterior disc height 3.6±0.90 vs 3.4±0.93 mm; p<0.01). Disc heights and axial dimensions at T4-5 were similar or smaller than at T2-3, but thereafter increased caudally (mean anterior disc height T4-5 and T10-11, 2.7±0.7 and 5.4±1.2 mm, respectively, in men; 2.6±0.8 and 5.1±1.3 mm, respectively, in women; p<0.05). Except at T2-3, anterior disc height decreased with advancing age and anteroposterior and transverse disc dimensions increased; posterior and middle disc heights and indices of disc shape showed no consistent statistically significant changes. Most parameters showed substantial to almost perfect agreement for intra- and inter-rater reliability. Thoracic disc morphometry varies significantly and consistently with disc level, sex and age. This study provides unique reference data on adult thoracic intervertebral disc morphometry, which may be useful when interpreting pathological changes and for future biomechanical and functional studies.

Quantitative MRI and X-ray analysis of disc degeneration and paraspinal muscle changes in degenerative spondylolisthesis.

The intervertebral disc degeneration changes and paraspinal muscles changes are believed to be risk factors for lumbar degenerative spondylolisthesis (LDS). But there is limited quantitative information about this progression. This study is to reveal their changes the in the progression of LDS. Data were gathered from 149 middle-aged degenerative spondylolisthesis patients and same amount of age- and sex-matched control group with both lumber spine MRI and X-ray. Narrowed disc space were measured in percent as anterior inferior disc height (DHIA)/anterior superior disc height (DHSA), inferior disc height (DHI)/superior disc height (DHS), and posterior inferior disc height (DHIP)/posterior superior disc height (DHSP). Signal intensity ratio of multifidus muscle (RM) and erector spinae (RES) to psoas muscle, muscle atrophy ratio of lean CSA (LCSA) to gross CSA (GCSA) of paraspinal muscles were calculated. In the case group the most common slipped vertebra was L4 (75.84%). Disc height (DHIA/DHSA, DHI/DHS) and multifidus muscle atrophy ratio (M-LCSA/M-GCSA) tended to be lower than those in the control group, whereas the disc degeneration degree and T2 signal intensity ratio (RM,RES) of the paraspinal muscles and erector spinae muscle atrophy ratio were higher than control group. The difference between the two groups was statistically significant (P< 0.05). Using multivariate logistic regression analysis, it was confirmed that ES-LCSA/ES-GCSA, especially RM are independent predisposing factors to lumbar spondylolisthesis (OR > 1, P< 0.05) while DHIA/DHSA, M-LCSA/M-GCSA are independent protective factors (OR < 1, P< 0.05). Decreased anterior disc height and multifidus muscle atrophy are found in the LDS patients and thy could be the cause of LDS. The presence of erector spinae hypertrophy could be a compensatory mechanism to compensate for the instability.

Finite element analysis of lordosis restoration with anterior longitudinal ligament release and lateral hyperlordotic cage placement.

Restoring sagittal alignment is an important factor in the treatment of spinal deformities. Recent investigations have determined that releasing the anterior longitudinal ligament (ALL) and placing hyperlordotic cages can increase lordosis, while minimizing need for 3 column osteotomies. The influences of parameters such as cage height and angle have not been determined. Finite element analysis was employed to assess the extent of lordosis achievable after placement of different sized lordotic cages. A 3-dimensional model of a L3-4 segment was used. Disc distraction was simulated by inserting interbody cages mid-body in the disc space. Analyses were performed in the following conditions: (1) intact, (2) ALL release, (3) ALL release + facetectomy, and (4) ALL release + posterior column osteotomy. Changes in segmental lordosis, disc height, foraminal height, and foraminal area were measured. After ALL resection and insertion of hyperlordotic cages, lordosis was increased in all cases. The lordosis achieved by the shorter cages was less due to posterior disc height maintained by the facet joints. A facetectomy increased segmental lordosis, but led to contact between the spinous processes. For some configurations, a posterior column osteotomy was required if the end goal was to match cage angle to intradiscal angle. Increased segmental lumbar lordosis is achievable with hyperlordotic cages after ALL resection. Increased cage height tended to increase the amount of lordosis achieved, although in some cases additional posterior bone resection was required to maximize lordosis. Further studies are needed to evaluate the impact on regional lumbar lordosis.

A morphometric analysis of contralateral neural foramen in TLIF

A retrospective review This study was designed to compare postoperative changes in neural foramen between transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF). A retrospective analysis of 67 patients was compared to the change of neural foraminal morphometry of the two techniques. 33 patients (40 levels) had TLIF and 34 patients (39 levels) had PLIF. The two groups had similar demographic profiles. Radiological parameters including anterior and posterior disc height, foraminal height (FH), and segmental Cobb angle (SCA) were measured by sagittally reconstructed computed tomography images before and after surgery. Cage position was designated as contralateral, middle, and ipsilateral in the TLIF group. Surgical results were assessed by Odom criteria, visual analog scale (VAS), and Oswestry disability index (ODI) scores. The TLIF and PLIF group showed no bilateral difference in FH. The TLIF group had increased contralateral SCA compared to the ipsilateral side postoperatively. FH differed according to cage position in the TLIF group. When a cage was inserted deeply into the contralateral side, contralateral FH increased significantly. However, when a cage was inserted into the ipsilateral side, contralateral FH decreased significantly. Back pain was significantly lower in the TLIF group at 1 and 6 months than in the PLIF group. However, ODI and Odom scale scores were not different between the groups. TLIF may induce uneven changes in foraminal morphometry. Cage position may be the major determinant of this result.

Treatment of Spinal Epidural Abscess and Predisposing Factors of Motor Weakness: Experience with 48 Patients.

ObjectiveSpinal epidural abscess (SEA) can be fatal if untreated, so early diagnosis and treatment are essential. We conducted a retrospective study to define its clinical features and evaluate the risk factors of motor weakness.MethodsWe retrospectively analyzed the medical records and images of patients with SEA who had been hospitalized in our institute from January 2005 to June 2012. Pyogenic SEA patients were categorized as patients without motor weakness (Group A) and with motor weakness (Group B). Abscess volume was measured using the Gamma-Plan program. Intervertebral foramen height and posterior disc height were measured to evaluate degree of spinal stenosis.ResultsOf 48 patients with pyogenic SEA, 33 (68%) were treated surgically, and 15 (32%) were treated with antibiotics. Eleven patients had weakness and abscess volume was unrelated to motor weakness. Old age, 'spare room' (abscess volume subtracted from spinal volume) and intervertebral foramen height and posterior disc height were statistically significant. Among the 48 patients, 43 (85%) had good outcome and erythrocyte sedimentation rate (ESR) was the only meaningful prognostic factor (p=0.014). The cut-off value of ESR was 112mm/h with 80% sensitivity and 79% specificity and had borderline significance (p=0.062).ConclusionSEA needs emergent diagnosis and treatment. Motor weakness is the most important factor in treatment decision. By careful image reading, early surgical treatment can be an option for selected patients with severe spinal stenosis for prevent motor weakness. Inflammatory markers, especially ESR, are valuable to identify worsening of SEA.