Evalina L. Burger

Retrograde Ejaculation After Anterior Lumbar Spine Surgery

Study Design. A retrospective cohort study. Objective. To compare the incidence of retrograde ejaculation (RE) after anterior lumbar spine surgery with disc replacement versus fusion with the use of recombinant human bone morphogenetic protein-2 (BMP). Summary of Background Data. Anterior lumbar interbody fusion (ALIF) has become a popular choice for treating a number of pathologies, largely because it preserves the posterior paravertebral muscles and ligaments. Despite these advantages, the anterior approach is also associated with various complications, one of which is RE. A recent study has questioned whether the risk of RE is increased by the use of BMP in ALIF procedures rather than by the approach alone. Methods. We conducted a retrospective review of all male patients who received ALIF using BMP or artificial disc replacement (ADR) on at least the L5–S1 level between 2004 and 2011. Medical records were evaluated for the occurrence of RE, and patients were contacted via the phone to obtain current information. The incidence of RE was then compared between the 2 anterior lumbar surgery procedures. Results. Of the 95 cases of anterior surgery including L5–S1, 54 patients underwent ALIF with BMP (56.8%) and 41 patients were treated with ADR (43.2%). Postoperative RE occurred in 4 of the 54 ALIF patients (7.4%) and in 4 of the 41 ADR patients (9.8%). The incidence of RE was not significantly different between groups (P = 0.7226). At latest follow-up, 1 ALIF and 1 ADR patient reported resolution of the RE. Conclusion. This study found that RE occurred at a similar rate in patients treated with ADR and ALIF with BMP. The overall rate of RE after retroperitoneal anterior lumbar surgery was higher than expected, which underscores the importance of counseling patients about this risk and specifically questioning patients about the symptoms of RE at postoperative visits.

High Rectal Injury During Trans-1 Axial Lumbar Interbody Fusion L5–s1 Fixation: A Case Report

Study Design. A Case Report Objective. To report a case of high rectal injury during trans-1 axial Lumbar Interbody Fusion (axiaLIF) L5–S1 fixation. Summary of Background Data. Trans-1 axiaLIF procedure is gaining in popularity for L5–S1 fusion due to the ease of access to the sacrum through the presacral space. Normally, the midline of the sacrum at S1–S2 is relatively free from neurovascular and intra-abdominal structures, making this level a safe entry point for the axiaLIF procedure. We report a case of high rectal injury during Trans-1 axiaLIF L5–S1 procedure due to altered intra-abdominal anatomy as a result of multifactorial adhesions formation. Methods. A 44-year-old female patient with a history of previous anterior and posterior spinal surgeries, pelvic inflammatory disease, and non-disclosed previous diverticulitis, developed a high rectal injury during Trans-1 axiaLIF L5–S1 fixation. Results. After Trans-1 axiaLIF L5–S1, the patient presented with an episode of melena and hypogastric pain with nausea and vomiting. A computed tomography(CT) scan of the abdomen with intravenous and oral contrast showed presacral soft tissue fluid density with fat stranding and extraluminal rectal contrast and gas with some areas of soft tissue enhancement compatible with probable high rectal perforation. Patients symptoms gradually subsided during a period of 6 months with aid from a temporary diverting ileostomy and a course of IV antibiotics. No spine implants were removed. Conclusion. We report a case of high rectal injury during Trans-1 axiaLIF L5–S1 fixation and strongly advice that patients who are candidates for this surgery and have any risk factors for intra-abdominal adhesion formation, undergo a pelvic CT with rectal contrast before the surgery to evaluate for any signs of altered rectal–sacral anatomy.

Calcium phosphates as bone graft extenders

Although iliac crest autograft is the gold standard for fusion, many patien experience permanent pain at the donor site that is likely underestimated in the literature. As the population requiring reconstructive spine surgery increases, so does the need for a successful substitute for autologous bone. One such large surface bone graft substitute that has gained popularity in spine surgery is calcium phosphate. However, the characteristics of various calcium phosphate products have not been previously reviewed in the literature. Thus, this article presents a comparative analysis of the physiochemical attributes of calcium phosphate materials used in spine surgery.

Lumbar spinal fusion versus anterior lumbar disc replacement: the financial implications.

Study Design Cost-identification analysis with retrospective and calculated cost. Objective To determine the relative cost of lumbar spinal fusion versus anterior lumbar disc replacement. Summary of Background Data Although several methods of treatment for lumbar spinal degenerative disc disease are currently accepted, no single treatment has been proven superior. In the past, the standard treatment has been spinal fusion; however, fusion surgery has many short and long-term limitations. Lumbar disc replacement surgery is now Food and Drug Administration-approved and is an accepted treatment in well selected patients. Initial results showed its equivalence with fusion in 2-year outcome studies, and more recent data has even indicated a superiority. In the current healthcare system, cost of the treatment plays a major role in the availability and acceptance of medical therapies. To date, cost analysis information has not been available for disc replacement surgery relative to spinal fusion. Methods A review of hospital costs was performed for 10 randomly selected patients in each group who underwent single-level lumbar transforaminal interbody fusion (TLIF), anterior and posterior spinal fusion (ASF/PSF), ASF alone, and anterior disc replacement. Additionally, the University Hospital Consortium database was queried for average cost per hospital day and average cost per operating room minute. These data were combined with ProDisc clinical IDE trial data to calculate the cost of each treatment. Results The actual cost of implants at our institution for ASF/PSF, ASF, TLIF, and disc replacement were similar when rhBMP-2 was not included in the calculations. Total hospital costs for ASF/PSF were significantly higher than for TLIF, ASF, or disc replacement. Conclusions The hospital cost of disc replacement surgery is similar to TLIF and ASF (when rhBMP-2 cost is excluded) and is significantly less expensive than ASF/PSF.

Posterior Versus Anterior Lumbar Interbody Fusion With Anterior Tension Band Plating: Retrospective Analysis

Over the past 2 decades, posterior lumbar interbody fusion (PLIF) with pedicle screw instrumentation has gained popularity. Anterior fusion techniques, however, have evolved over time and currently allow for minimally invasive anterior retroperitoneal diskectomy, interbody graft placement, and rigid instrumentation. A direct comparison of anterior lumbar interbody fusion (ALIF) with anterior tension band plating to that of instrumented PLIF has not been previously reported. This retrospective uncontrolled cohort comparison included 59 patients with low back pain and 1- or 2-level lumbar degenerative disk disease from L3 to S1 who underwent PLIF with pedicle screw instrumentation or ALIF with anterior tension band plating. Outcome measures included estimated blood loss, surgical time, radiographic evidence of fusion at 6 to 9 months postoperatively, and pre- and postoperative Oswestry Disability Index scores. Fusion rates for the 2 procedures were similar. Posterior lumbar interbody fusion patients had significantly higher estimated blood loss and longer surgical time than ALIF-ATB patients. Oswestry Disability Index scores were similar between the 2 groups at all postoperative time points, except at 3 months postoperatively when PLIF patients had lower scores than ALIF-ATB patients. These findings suggest that ALIF-ATB has similar fusion and functional outcomes as PLIF, but with shorter surgical time and decreased blood loss.

Mineralization and collagen orientation throughout aging at the vertebral endplate in the human lumbar spine.

The human vertebral body and intervertebral disc interface forms the region where the cartilaginous endplate, annulus fibrosis and bone of the vertebral body are connected through an intermediate calcified cartilage layer. While properties of both the vertebral body and components of the disc have been extensively studied, limited quantitative data exists describing the microstructure of the vertebral body-intervertebral disc interface in the spine throughout development and degeneration. Quantitative backscattered scanning electron and second harmonic generation confocal imaging were used to collect quantitative data describing the mineral content and collagen fiber orientation across the interface, respectively. Specimens spanned ages 56 days to 84 years and measurements were taken across the vertebral endplate at the outer annulus, inner annulus and nucleus pulposis. In mature and healthy endplates, collagen fibers span the calcified cartilage layer in all regions, including the endplate adjacent to the central nucleus pulposis. We also observed an abrupt transition from high mineral volume fractions (35-50%) to 0% over short distances measuring 3-15 microns in width across the transition from calcified cartilage to unmineralized cartilage. The alignment of collagen fibers at the outer annulus and thickness of the CC layer indicated that collagen fiber mineralization adjacent to the bone may serve to anchor the soft tissue without a gradual change in material properties. Combining backscattered scanning electron microscopy and second harmonic generation imaging on the same sections thus enable a novel assessment of morphology and properties in both mineralized and soft tissues at the vertebral body-intervertebral disc throughout development and aging.

Pedicle Screw Placement With O-arm and Stealth Navigation

Various navigation systems are available to aid pedicle screw placement. The O-arm replaces the need for fluoroscopy and generates a 3-dimensional volumetric dataset that can be viewed as transverse, coronal, and sagittal images of the spine, similar to computed tomography (CT) scanning. The dataset can be downloaded to the Stealth system (Medtronic Navigation, Louisville, Colorado) for real-time intraoperative navigation.The main objectives of the current study were to assess (1) accuracy of pedicle screw placement using the O-arm/Stealth system, and (2) time for draping, positioning of the O-arm, and screw placement. Of 188 screws (25 patients), 116 had adequate images for analysis. The average time for O-arm draping was 3.5 minutes. Initial O-arm positioning was 6.1 minutes, and final positioning was 4.9 minutes. Mean time for screw placement, including O-arm draping and positioning and array attachment, was 8.1 minutes per screw. Mean time for screw placement alone was 5.9 minutes per screw. Screw placements on final O-arm images were on average 3.14 mm deeper than on the snapshot navigation images. Three screws (2.6%) breached the medial cortex, and 3 screws (2.6%) were misaligned and did not follow the pilot hole trajectory.The use of the O-arm/Stealth system was associated with a low rate of pedicle screw misalignment. The time to place screws was less than previously reported with CT navigation, but longer than conventional techniques. It is important to be aware of the potential discrepancy between snapshot navigation images and actual screw placement on final O-arm images. Our findings suggest that final screw positions may be deeper than awl positions appear on navigation images.

Predictors of spine deformity progression in adolescent idiopathic scoliosis: A systematic review with meta-analysis

AIM To evaluate published data on the predictors of progressive adolescent idiopathic scoliosis (AIS) in order to evaluate their efficacy and level of evidence. METHODS SELECTION CRITERIA (1) study design: randomized controlled clinical trials, prospective cohort studies and case series, retrospective comparative and none comparative studies; (2) participants: adolescents with AIS aged from 10 to 20 years; and (3) treatment: observation, bracing, and other. SEARCH METHOD Ovid MEDLINE, Embase, the Cochrane Library, PubMed and patent data bases. All years through August 2014 were included. Data were collected that showed an association between the studied characteristics and the progression of AIS or the severity of the spine deformity. Odds ratio (OR), sensitivity, specificity, positive and negative predictive values were also collected. A meta-analysis was performed to evaluate the pooled OR and predictive values, if more than 1 study presented a result. The GRADE approach was applied to evaluate the level of evidence. RESULTS The review included 25 studies. All studies showed statistically significant or borderline association between severity or progression of AIS with the following characteristics: (1) An increase of the Cobb angle or axial rotation during brace treatment; (2) decrease of the rib-vertebral angle at the apical level of the convex side during brace treatment; (3) initial Cobb angle severity (> 25(o)); (4) osteopenia; (5) patient age < 13 years at diagnosis; (6) premenarche status; (7) skeletal immaturity; (8) thoracic deformity; (9) brain stem vestibular dysfunction; and (10) multiple indices combining radiographic, demographic, and physiologic characteristics. Single nucleotide polymorphisms of the following genes: (1) calmodulin 1; (2) estrogen receptor 1; (3) tryptophan hydroxylase 1; (3) insulin-like growth factor 1; (5) neurotrophin 3; (6) interleukin-17 receptor C; (7) melatonin receptor 1B, and (8) ScoliScore test. Other predictors included: (1) impairment of melatonin signaling in osteoblasts and peripheral blood mononuclear cells (PBMC); (2) G-protein signaling dysfunction in PBMC; and (3) the level of platelet calmodulin. However, predictive values of all these findings were limited, and the levels of evidence were low. The pooled result of brace treatment outcomes demonstrated that around 27% of patents with AIS experienced exacerbation of the spine deformity during or after brace treatment, and 15% required surgical correction. However, the level of evidence is also low due to the limitations of the included studies. CONCLUSION This review did not reveal any methods for the prediction of progression in AIS that could be recommended for clinical use as diagnostic criteria.

Perioperative and long-term clinical outcomes for bone morphogenetic protein versus iliac crest bone graft for lumbar fusion in degenerative disk disease: systematic review with meta-analysis.

Study Design: Systematic review with meta-analysis. Objectives: To compare the perioperative and long-term postoperative effectiveness of bone morphogenetic protein (BMP) for lumbar arthrodesis in skeletally mature adults with degenerative disk disease (DDD) to that of the current golden standard treatment, iliac crest autologous bone graft (ICBG). Summary of Background Data: The treatment efficacy of lumbar arthrodesis in DDD is a complex clinical and economic issue for patients and health care providers. Methods: Comprehensive electronic literature search was performed using following databases: Ovid MEDLINE; Embase; Cochrane Library; Central Register of Controlled Trials (CENTRAL); Database of Abstracts of Reviews of Effects; Methodology Register; Technology Assessment Database; and Economic Evaluation Database. The full year ranges of each database until May of 2012 were included. Results: Eight randomized controlled clinical trials of 383 citations were selected. The included studies involved 1138 participants. The pooled 2-year postoperative clinical outcomes were equivalent in BMP and ICBG groups, and exceeded minimum clinically important differences for Oswestry Disability Index, SF-36 (physical scale), and numeric rating scale (back pain). ICBG was associated with increased pain and complications at the donor site (P<0.01). The pooled average operative time was 21 minutes less in BMP versus ICBG (P<0.001). The pooled rate of additional surgical treatment was 2 times less in the BMP than in the ICBG groups (P=0.006). The pooled risk of nonunion at 24-month follow-up was 2 times less in the BMP than in the ICBG groups (P=0.037), however, this effect was likely biased. Conclusions: BMP, in particular rhBMP-2, is a good alternative to autogenous bone graft, especially in cases when harvesting of autologous bone is contraindicated or undesirable, operation time is limited, and there are no contraindications for BMP use. However, the current study did not reveal evidence robust enough to develop strong medical recommendations concerning BMP use for lumbar arthrodesis in degenerative disk disease.

Small peptide (P-15) bone substitute efficacy in a rabbit cancellous bone model

P-15 is a synthetic 15-amino acid residue identical to the cell binding domain of type I collagen. P-15 can be adsorbed onto anorganic bovine bone mineral (ABM) and will enhance cell attachment and subsequent cell activation. Although ABM/P-15 has been studied as a bone graft substitute in the oral cavity, its use in orthopedic models has been limited. Thus, this study investigated the efficacy of ABM/P-15 treatment in a rabbit model of long bone cancellous healing. Defects were created in the distal femurs and proximal medial tibiae of rabbits and were filled with either ABMP/P-15 suspended in hydrogel, ABM alone suspended in hydrogel, hydrogel carrier alone, or no graft material. Rabbits were sacrificed at 1, 2, 4, or 8 weeks postsurgery, and the femurs and tibiae were harvested. Histomorphometric analyses indicated that defects treated with ABM/P-15 had significantly larger areas of new bone formation than the other three treatments at 2 and 8 weeks postsurgery. ABM/P-15 treated defects also had significantly more bone growth than defects left empty or filled with ABM alone at 4 weeks postsurgery. Furthermore, histological examination did not reveal acute inflammatory infiltrate cells in any of the treatment conditions. These results are consistent with the findings of ABM/P-15 use in human oral-maxillofacial studies and in large animal spine fusion models.