Retrograde ejaculation after anterior lumbar interbody fusion with and without bone morphogenetic protein-2 augmentation: a 10-year cohort controlled study

Restoring L4-S1 Lordosis Shape in Severe Sagittal Deformity: Impact of Correction Techniques on Alignment and Complication Profile

BACKGROUND

Severe sagittal plane deformity with loss of L4-S1 lordosis is disabling and can be improved through various surgical techniques. However, data are limited on the differing ability of anterior lumbar interbody fusion (ALIF), pedicle subtraction osteotomy (PSO), and transforaminal lumbar interbody fusion (TLIF) to achieve alignment goals in severely malaligned patients.

METHODS

Severe adult spinal deformity patients with preoperative PI-LL >20°, L4-S1 lordosis <30°, and full body radiographs and PROMs at baseline and 6-week postoperative visit were included. Patients were grouped into ALIF (1-2 level ALIF at L4-S1), PSO (L4/L5 PSO), and TLIF (1-2 level TLIF at L4-S1). Comparative analyses were performed on demographics, radiographic spinopelvic parameters, complications, and PROMs.

RESULTS

Among the 96 included patients, 40 underwent ALIF, 27 underwent PSO, and 29 underwent TLIF. At baseline, cohorts had comparable age, sex, race, Edmonton frailty scores, and radiographic spinopelvic parameters (P > 0.05). However, PSO was performed more often in revision cases (P < 0.001). Following surgery, L4-S1 lordosis correction (P = 0.001) was comparable among ALIF and PSO patients and caudal lordotic apex migration (P = 0.044) was highest among ALIF patients. PSO patients had higher intraoperative estimated blood loss (P < 0.001) and motor deficits (P = 0.049), and in-hospital ICU admission (P = 0.022) and blood products given (P = 0.004), but were otherwise comparable in terms of length of stay, blood transfusion given, and postoperative admission to rehab. Likewise, 90-day postoperative complication profiles and 6-week PROMs were comparable as well.

CONCLUSIONS

ALIF can restore L4-S1 sagittal alignment as powerfully as PSO, with fewer intraoperative and in-hospital complications. When feasible, ALIF is a suitable alternative to PSO and likely superior to TLIF for correcting L4-S1 lordosis among patients with severe sagittal malalignment.

Discussing sexual health with patients eligible for spine surgery: An online survey in spine surgeon and pain physicians

Introduction

Spinal pain syndromes have a severe impact on the patient's sex life, contributing to a decrease in sexual function and sexual satisfaction. Despite the importance of sexual health on mental and physical wellbeing, sexual health is rarely discussed during consultations.

Research question

The aim of this study is to explore to what extent influencing factors can alter the discussion about sexual health during consultations. More specifically, we will evaluate the influence of healthcare profession, sex of the patient and the surgical approach that is proposed.

Material and methods

An online survey was sent to neurosurgeons, pain physicians and orthopedists in Belgium and The Netherlands in April 2019. Participants were asked about; counseling routine, knowledge, and opinion on sexual health. Answers were scored on a 5-point Likert scale. Independence between the response levels and type of surgery as well as profession were tested.

Results

In total, 350 respondents were approached of whom 57 completed the survey. The majority of respondents (61.4%) indicated that they rarely or never discussed sexual disturbances. Profession and type of surgery had an influence on discussing erectile dysfunction, retrograde ejaculation, and alterations in orgasms. Thirty-five percent of healthcare providers considered it the patient's responsibility to bring up the subject of sexual health.

Discussion and conclusion

Sexual health is rarely addressed by healthcare providers during spinal care. Profession as well as type of surgery seems to play a role on whether sexual health is discussed during consultations.

Osteobiologies for Spinal Fusion from Biological Mechanisms to Clinical Applications: A Narrative Review

Degenerative lumbar spinal disease (DLSD), including spondylolisthesis and spinal stenosis, is increasing due to the aging population. Along with the disease severity, lumbar interbody fusion (LIF) is a mainstay of surgical treatment through decompression, the restoration of intervertebral heights, and the stabilization of motion segments. Currently, pseudoarthrosis after LIF is an important and unsolved issue, which is closely related to osteobiologies. Of the many signaling pathways, the bone morphogenetic protein (BMP) signaling pathway contributes to osteoblast differentiation, which is generally regulated by SMAD proteins as common in the TGF-β superfamily. BMP-2 and -4 are also inter-connected with Wnt/β-catenin, Notch, and FGF signaling pathways. With the potent potential for osteoinduction in BMP-2 and -4, the combination of allogenous bone and recombinant human BMPs (rhBMPs) is currently an ideal fusion material, which has equalized or improved fusion rates compared to traditional materials. However, safety issues in the dosage of BMP remain, so overcoming current limitations will provide significant advancement in spine surgery. In the future, translational research and the application of clinical study will be important to overcome the current limitations of spinal surgery.

Trends, payments, and costs associated with BMP use in Medicare beneficiaries undergoing spinal fusion

BACKGROUND CONTEXT

Bone morphogenic protein (BMP) promotes bony fusion but increases costs. Recent trends in BMP use among Medicare patients have not been well-characterized.

PURPOSE

To assess utilization trends, complication, payments, and costs associated with BMP use in spinal fusion in a Medicare-insured population.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Total of 316,070 patients who underwent spinal fusion in a 20% sample of Medicare-insured patients, 2006 to 2015.

OUTCOME MEASURES

Utilization trends across time and geography, complications, payments, and costs.

METHODS

Patients were stratified by fusion type and diagnosis. Multivariable logistic and linear regression were used to adjust for the effect of baseline characteristics on complications and total payments or cost, respectively.

RESULTS

BMP was used in 60,249 cases (19.1%). BMP utilization rates decreased from 23.1% in 2006 to 12.0% in 2015, most significantly in anterior cervical (7.5%-3.1%), posterior cervical (17.0%-8.3%), and posterior lumbar fusions (31.5%-15.8%). There are significant state- and region-level geographic differences in BMP utilization. Across all years, states with the highest BMP use were Indiana (28.5%), Colorado (26.6%), and Nevada (25.7%). States with the lowest BMP use were Maine (2.3%), Vermont (8.2%), and Mississippi (10.4%). After multivariate risk adjustment, BMP use was associated with decreased overall complications in thoracic (odds ratios [OR] [95% confidence intervals [CI]): 0.89 [0.81-0.99]) and anterior lumbar fusions (OR [95% CI]: 0.89 [0.84-0.95]), as well as increased reoperation rates in anterior cervical (OR [95% CI]: 1.11 [1.04-1.19]), posterior cervical (OR (95% CI): 1.14 (1.04-1.25)), thoracic (OR (95% CI): 1.32 (1.23-1.41)), and posterior lumbar fusions (OR (95% CI): 1.11 (1.06-1.16)). BMP use was also associated with greater total costs, independent of fusion type, after multivariate risk adjustment (p<.0001). Payments, however, were comparable between groups in anterior and posterior cervical fusion with or without BMP. BMP use was associated with greater total payments in thoracic, anterior lumbar, and posterior lumbar fusions. Notably, the difference in payments was smaller than the associated cost increase in all fusion types.

CONCLUSIONS

BMP use has declined across all fusion types over the last decade, after a peak in 2007. While BMP is associated with greater costs, reimbursement does not increase proportionally with BMP cost.

Lumbar Interbody Fusion and Osteobiologics for Lumbar Fusion

Lumbar interbody fusion (LIF) is an excellent treatment option for a number of lumbar diseases. LIF can be performed through posterior, transforaminal, anterior, and lateral or oblique approaches. Each technique has its own pearls and pitfalls. Through LIF, segmental stabilization, neural decompression, and deformity correction can be achieved. Minimally invasive surgery has recently gained popularity and each LIF procedure can be performed using minimally invasive techniques to reduce surgery-related complications and improve early postoperative recovery. Despite advances in surgical technology, surgery-related complications after LIF, such as pseudoarthrosis, have not yet been overcome. Although autogenous iliac crest bone graft is the gold standard for spinal fusion, other bone substitutes are available to enhance fusion rate and reduce complications associated with bone harvest. This article reviews the surgical procedures and characteristics of each LIF and the osteobiologics utilized in LIF based on the available evidence.

L4 Corpectomy: Surgical Approaches and Mitigating the Risk of Femoral Nerve Injuries

OBJECTIVE

Because of the challenging anatomic location, corpectomies are performed less often at the fourth lumbar vertebral body than at other levels. Our objective was to review the literature of L4 corpectomy and anterior column reconstruction.

METHODS

A literature search in the Medline/PubMed database was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify all relevant cases and cases series describing corpectomies of the L4 vertebral body using "lumbar" AND "corpectomy" as search terms. We present an illustrative case to describe the technique.

RESULTS

We identified 18 articles with 30 patients who met the search criteria. Including our case illustration, the most common approach used was the lateral retroperitoneal approach (n = 17, 54.8%), of which 8 (26.7%) were performed via a transpsoas approach. Seven (23%) patients underwent corpectomy through a posterior approach, 4 (12.9%) through an anterior retroperitoneal approach, and 3 (10%) through combined anterior and lateral retroperitoneal. The overall complications rate was 19.3% including 1 case each of femoral nerve injury and iatrogenic lumbar nerve root injury.

CONCLUSIONS

Corpectomies of the L4 vertebral body are challenging. None of the various approaches described clearly demonstrates any superiority in mitigating the risk of neural complications. Decision making about which surgical approach to use should be based on patient-specific characteristics.

Age-Related Low Bone Mineral Density in C57BL/6 Mice Is Reflective of Aberrant Bone Morphogenetic Protein-2 Signaling Observed in Human Patients Diagnosed with Osteoporosis

Osteoporosis (OP) is a bone disorder characterized by decreased bone mineral density (BMD). Bone Morphogenetic Protein-2 (BMP-2) injections are used to promote bone formation in OP patients. However, patients are unresponsive to BMP-2 while displaying an upregulation of BMP Receptor Type 1a (BMPRIa) and protein kinase CK2α (CK2α). A synthetically produced peptide named casein kinase 2.3 (CK2.3) utilizes the BMP-signaling pathway as it enhances osteogenesis of primary osteoblasts isolated from OP patients, whereas BMP-2 does not. Although shown in OP patients, there is currently no reliable mouse model to study BMP-2 and CK2.3 signaling. In this publication, we show that BMPRIa was required for CK2.3-mediated osteogenesis in C2C12 cells with a CRISPR-Cas9-mediated gene knockout for BMPRIa. We utilized the C57BL/6 (B6) mouse strain as an aging-model to study aberrant BMP-2 signaling, demonstrating that, like OP patients, in 15 and 20-month mice, BMP-2 did not increase bone growth and displayed upregulated BMPRIa and CK2α protein expression. Furthermore, CK2.3 enhanced osteogenesis and decreased osteoclastogenesis in all age groups, whereas BMP-2 only increased mineralization in 6-month mice while increasing osteoclast formation in all age groups. These data demonstrated that aging B6 mice were a reliable model and mimicked data obtained from OP patients.

Risk Assessment of Anterior Lumbar Interbody Fusion Access in Degenerative Spinal Conditions

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

Develop an evidence-based preoperative risk assessment scoring system for patients undergoing anterior lumbar interbody fusion (ALIF).

SUMMARY OF BACKGROUND DATA

ALIF may hold advantages over other fusion techniques in sagittal restoration and fusion rates, though it introduces unique risks to vascular and abdominal structures and thus possibly increased risk of operative morbidity.

METHODS

Primary, 1 or 2-level ALIFs were identified in a surgical registry. Baseline characteristics were recorded. Axial magnetic resonance imagings at L4-L5 and L5-S1 were reviewed for vascular confluence/bifurcation or anomalous structures, and measured for operative window size/slope. To assess favorable outcomes, a clinical grade was calculated: (clinical grade=blood loss×operative duration), higher value indicating poorer outcome. To establish a risk scoring system, a base risk score algorithm was established and stratified into 5 categories: high, high to intermediate, intermediate, intermediate to low, and low. Modifiers to base risk score included age, body mass index, operative level, history of bone morphogenic protein use, calcified vasculature, spondylolisthesis grade, working window size and slope, and abnormal vasculature. Modifiers were weighted for contribution to surgical risk. A total risk score was calculated and evaluated for strength of association with clinical outcome grades by Pearson correlation coefficient.

RESULTS

A total of 65 patients were included. Mean clinical outcome grade was 5.6, mean total risk score 21.3±21.5. Multilevel procedures (L4-S1) mean total risk score was 57.3±7.8. L4-L5 mean total risk score was 23.6±5.2; L5-S1 mean total risk score 8.3±6.6. Correlation analysis demonstrated a significant and strong relationship (| r |=0.753; P <0.001) between total risk scores and clinical outcome grades.

CONCLUSION

Calculated ALIF risk scores significantly correlated with operative duration and blood loss. This scoring system represents a potential framework to facilitate clinical decision-making and risk assessment for potential ALIF candidates with degenerative spinal pathologies.

Long-term Outcomes of Minimally Invasive Lateral Lumbar Interbody Fusion in the Treatment of Adult Scoliosis

The literature has shown the importance of long-term follow-up for adults with scoliosis treated surgically because complication and revision rates are high. The goal of this study was to determine long-term outcomes and complications of lateral lumbar interbody fusion (LLIF) with posterior instrumentation for adult patients with scoliosis. A retrospective review of our institution's database was performed to identify adult patients with scoliosis treated with LLIF between 2008 and 2013 with a minimum follow-up of 4 years. Medical records were reviewed for complications and revisions. Pre- and postoperative deformity Cobb angle measurements were taken as well as pelvic incidence (PI) and lumbar lordosis (LL). Functional outcome scores, including Oswestry Disability Index and visual analog scale score for back and leg pain, were assessed preoperatively and at follow-up. Standard binomial and categorical comparative analysis was performed. The 26 patients included had a mean age of 62 years, mean follow-up of 89 months, and mean of 1.8 levels per operation. Four patients (15.4%) required revisions. Mean deformity Cobb angle was 26° preoperatively and 14° postoperatively. Mean PI-LL mismatch was 11.7° preoperatively and 5.9° postoperatively. Nineteen (73%) patients had a PI-LL mismatch greater than 10° preoperatively, whereas only 2 (7.7%) had a mismatch postoperatively. Improvement was seen in all functional outcome scores. Long-term clinical results of LLIF for adults with deformity showed a low proportion of revision in the treatment of a condition with an established high rate of revision. The ability to reduce pelvic mismatch may further reduce the rate of revision. In this study, LLIF resulted in improved functional outcomes and patient satisfaction. [Orthopedics. 2022;45(3):e134-e139.].

Delayed Ejaculation After Lumbar Spine Surgery: A Claims Database Analysis

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

Delayed ejaculation (DE) is a distressing condition characterized by a notable delay in ejaculation or complete inability to achieve ejaculation, and there are no existing reports of DE following lumbar spine surgery. Inspired by our institutional experience, we sought to assess national rates of DE following surgery of the lumbar spine.

METHODS

We queried the Optum De-identified Clinformatics Database for adult men undergoing surgery of the lumbar spine between 2003 and 2017. The primary outcome was the development of DE within 2 years of surgery. Multivariable logistic regression was performed to identify factors associated with the development of DE.

RESULTS

We identified 117 918 men who underwent 162 646 lumbar spine surgeries, including anterior lumbar interbody fusion (ALIF), posterior lumbar fusion (PLF), and more. The overall incidence of DE was 0.09%, with the highest rate among ALIF surgeries at 0.13%. In multivariable analysis, the odds of developing DE did not vary between anterior/lateral lumbar interbody fusion, PLF, and other spine surgeries. A history of tobacco smoking (OR = 1.47, 95% CI 1.00-2.16, P = .05) and obesity (OR = 1.56, 95% CI 1.00-2.44, P = .05) were associated with development of DE.

CONCLUSIONS

DE is a rare but distressing complication of thoracolumbar spine surgery, and patients should be queried for relevant symptoms at postoperative visits when indicated.

Single position lateral decubitus anterior lumbar interbody fusion (ALIF) and posterior fusion reduces complications and improves perioperative outcomes compared with traditional anterior-posterior lumbar fusion

BACKGROUND CONTEXT

Lateral decubitus single position anterior-posterior (AP) fusion utilizing anterior lumbar interbody fusion and percutaneous posterior fixation is a novel, minimally invasive surgical technique. Single position lumbar surgery (SPLS) with anterior lumbar interbody fusion (ALIF) or lateral lumbar interbody fusion (LLIF) has been shown to be a safe, effective technique. This study directly compares perioperative outcomes of SPLS with lateral ALIF vs. traditional supine ALIF with repositioning (FLIP) for degenerative pathologies.

PURPOSE

To determine if SPLS with lateral ALIF improves perioperative outcomes compared to FLIP with supine ALIF.

STUDY DESIGN/SETTING

Multicenter retrospective cohort study.

PATIENT SAMPLE

Patients undergoing primary AP fusions with ALIF at 5 institutions from 2015 to 2020.

OUTCOME MEASURES

Levels fused, inclusion of L4-L5, L5-S1, radiation dosage, operative time, estimated blood loss (EBL), length of stay (LOS), perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), and PI-LL mismatch.

METHODS

Retrospective analysis of primary ALIFs with bilateral percutaneous pedicle screw fixation between L4-S1 over 5 years at 5 institutions. Patients were grouped as FLIP or SPLS. Demographic, procedural, perioperative, and radiographic outcome measures were compared using independent samples t-tests and chi-squared analyses with significance set at p <.05. Cohorts were propensity-matched for demographic or procedural differences.

RESULTS

A total of 321 patients were included; 124 SPS and 197 Flip patients. Propensity-matching yielded 248 patients: 124 SPLS and 124 FLIP. The SPLS cohort demonstrated significantly reduced operative time (132.95±77.45 vs. 261.79±91.65 min; p <0.001), EBL (120.44±217.08 vs. 224.29±243.99 mL; p <.001), LOS (2.07±1.26 vs. 3.47±1.40 days; p <.001), and rate of perioperative ileus (0.00% vs. 6.45%; p =.005). Radiation dose (39.79±31.66 vs. 37.54±35.85 mGy; p =.719) and perioperative complications including vascular injury (1.61% vs. 1.61%; p =.000), retrograde ejaculation (0.00% vs. 0.81%, p =.328), abdominal wall (0.81% vs. 2.42%; p =.338), neuropraxia (1.61% vs. 0.81%; p =.532), persistent motor deficit (0.00% vs. 1.61%; p =.166), wound complications (1.61% vs. 1.61%; p =.000), or VTE (0.81% vs. 0.81%; p =.972) were similar. No difference was seen in 90-day return to OR. Similar results were noted in sub-analyses of single-level L4-L5 or L5-S1 fusions. On radiographic analysis, the SPLS cohort had greater changes in LL (4.23±11.14 vs. 0.43±8.07 deg; p =.005) and PI-LL mismatch (-4.78±8.77 vs. -0.39±7.51 deg; p =.002).

CONCLUSIONS

Single position lateral ALIF with percutaneous posterior fixation improves operative time, EBL, LOS, rate of ileus, and maintains safety compared to supine ALIF with prone percutaneous pedicle screws between L4-S1.

Bone Graft Options in Spinal Fusion: A Review of Current Options and the Use of Mesenchymal Cellular Bone Matrices

BACKGROUND

Spinal fusion is the mainstay treatment for various spinal conditions ranging from lumbar and cervical stenosis to degenerative spondylolisthesis as well as extensive deformity corrections. A new emerging category of allograft is cellular bone matrices (CBMs), which take allogeneic mesenchymal stem cells and incorporate them into an osteoconductive and osteoinductive matrix. This study reviewed the current spinal fusion options and new emerging treatment options.

METHODS

Articles were searched using PubMed. The search included English publications since January 1, 2014, using the search terms "cellular bone matrix," "mesenchymal stem cells spinal fusion," "spinal arthrodesis AND mesenchymal stem cells," and "spine fusion AND cellular bone matrix."

RESULTS

Spinal fusion is accomplished through the use of allografts, autografts, and bone graft substitutes in combination or alone. An emerging category of allograft is CBMs, in which an osteoconductive and osteoinductive matrix is filled with mesenchymal stem cells. Studies demonstrate that CBMs have achieved equivalent or better fusion rates compared with traditional options for anterior cervical discectomy and fusions and posterolateral lumbar fusions; however, the studies have been retrospective and lacking control groups and therefore not ideal.

CONCLUSIONS

Many treatment options have been successfully used in spinal fusion. Newer allografts such as CBMs have shown promising results in both animal and clinical studies. Further research is needed to determine the therapeutic dose of mesenchymal stem cells delivered within CBMs.

Comparative Study of Radiological and Clinical Outcomes in Patients Undergoing Minimally Invasive Lateral Lumbar Interbody Fusion Using Demineralized Bone Matrix Alone or with Low-Dose Escherichia coli-Derived rhBMP-2

OBJECTIVE

To compare the results of interbody fusion in patients undergoing minimally invasive lateral lumbar interbody fusion (LLIF) using demineralized bone matrix (DBM) alone versus DBM+recombinant human bone morphogenetic protein-2 (rhBMP2).

METHODS

This retrospective case-controlled study was conducted in patients undergoing minimally invasive LLIF (n = 54) for lumbar interbody fusion; they were divided into 2 groups: DBM-only group and DMB+rhBMP2 group. The improvements of segmental and lumbar lordosis and restoration of disc height were measured, and the interbody fusion rates were determined using a modified Bridwell grading system. Clinical outcomes after surgery, such as visual analog scale scores of back pain and leg pain, and Oswestry disability index were compared.

RESULTS

There were no significant differences in disc height, lumbar and segmental lordosis, or interbody fusion rate between the 2 groups. However, the proportion of Bridwell grade 1 as complete interbody bridging was higher in the DBM+rhBMP2 group than in the DBM-only group at both 6 and 12 months (P < 0.001). Clinical parameters showed equally significant improvement during follow-up in both groups, with no significant differences between the groups.

CONCLUSION

In minimally invasive LLIF, adding Escherichia coli-derived rhBMP2 to DBM did not affect clinical outcomes or radiation parameters, but increased the speed of fusion and interbody bony bridging rate.

Is there a variance in complication types associated with ALIF approaches? A systematic review

Purpose

Anterior lumbar interbody fusion (ALIF) is a well-established alternative to posterior-based interbody fusion techniques, with approach variations, such as retroperitoneal, transperitoneal, open, and laparoscopic well described. Variable rates of complications for each approach have been enumerated in the literature. The purpose of this study was to elucidate the comparative rates of complications across approach type.

Methods

A systematic review of search databases PubMed, Google Scholar, and OVID Medline was made to identify studies related to complication-associated ALIF. PRISMA guidelines were utilised for this review. Meta-analysis was used to compare intraoperative and postoperative complications with ALIF for each approach.

Results

A total of 4575 studies were identified, with 5728 patients across 31 studies included for review following application of inclusion and exclusion criteria. Meta-analysis demonstrated the transperitoneal approach resulted in higher rates of retrograde ejaculation (RE) (p < 0.001; CI = 0.05–0.21) and overall rates of complications (p = 0.05; CI = 0.00–0.23). Rates of RE were higher at the L5/S1 intervertebral level. Rates of vessel injury were not significantly higher in either approach method (p = 0.89; CI =  − 0.04–0.07). Rates of visceral injury did not appear to be related to approach method. Laparoscopic approaches resulted in shorter inpatient stays (p = 0.01).

Conclusion

Despite the transperitoneal approach being comparatively underpowered, its use appears to result in a significantly higher rate of intraoperative and postoperative complications, although confounders including use of bone morphogenetic protein (BMP) and spinal level should be considered. Laparoscopic approaches resulted in shorter hospital stays; however, its steep learning curve and longer operative time have deterred surgeons from its widespread adaptation.

Retrograde ejaculation following anterior lumbar surgery: a systematic review and pooled analysis

OBJECTIVE

The present systematic review and pooled analysis aims to assess the incidence and risk factors for the development of retrograde ejaculation (RE) following first-time open anterior lumbar surgery.

METHODS

A systematic MEDLINE review via PubMed was performed, identifying 130 clinical papers relating to the topic. Eighteen publications were selected according to predetermined inclusion and exclusion criteria and were used to determine the incidence of RE. Only the publications that provided data on surgical risk factors present specifically in the men in the study were included in the analysis of risk factors.

RESULTS

Of the 2503 men included, there were 57 reported events of RE (2.3%). Of the cases for which long-term data were provided, 45.8% had resolved by final follow-up. There was a statistically significant increased risk associated with a transperitoneal as opposed to a retroperitoneal approach (8.6% vs 3.2%), as well as with the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in anterior lumbar interbody fusion (ALIF) as opposed to ALIF with bone graft or arthroplasty in controls (5.0% vs 1.8%). However, when excluding from analysis the patients operated on prior to the FDA's 2008 warning that commented on the drug's neuroinflammatory properties, there was no significant difference in rates of RE in patients receiving rhBMP-2 versus the control group (2.4% vs 2.5%). There was no significant difference in risk based on single- versus multilevel procedure or on ALIF versus arthroplasty.

CONCLUSIONS

In a pooled analysis of currently published data on men undergoing first-time open anterior lumbar surgery, this study found an overall incidence of RE of 2.3%. Nearly half of these patients recovered, reporting resolution of symptoms anywhere between 3 months and 48 months. Analysis of risk factors was limited by a paucity of published literature segregating data by sex. However, there was an increased risk associated with rhBMP-2 only when including data collected prior to the FDA warning on its detrimental properties. The authors therefore posit that the risk of RE is probably overestimated in the literature, given that the vast majority of the data available were collected prior to this warning and given the subsequent implementation of precautions when handling rhBMP-2.

Dose Adjustment Associated Complications of Bone Morphogenetic Protein: A Longitudinal Assessment

OBJECTIVE

Bone morphogenetic protein (BMP) is a growth factor that aids in osteoinduction and promotes bone fusion. There is a lack of literature regarding recombinant human BMP-2 (rhBMP-2) dosage in different spine surgeries. This study aims to investigate the trends in rhBMP-2 dosage and the associated complications in spinal arthrodesis.

METHODS

A retrospective study was conducted investigating spinal arthrodesis using rhBMP-2. Variables including age, procedure type, rhBMP-2 size, complications, and postoperative imaging were collected. Cases were grouped into the following surgical procedures: anterior lumbar interbody fusion/extreme lateral interbody fusion (ALIF/XLIF), posterior lumbar interbody fusion/transforaminal lumbar interbody fusion (PLIF/TLIF), posterolateral fusion (PLF), anterior cervical discectomy and fusion (ACDF), and posterior cervical fusion (PCF).

RESULTS

A total of 1209 patients who received rhBMP-2 from 2006 to 2020 were studied. Of these, 230 were categorized as ALIF/XLIF, 336 as PLIF/TLIF, 243 as PLF, 203 as ACDF, and 197 as PCF. PCF (P < 0.001), PLIF/TLIF (P < 0.001), and PLF (P < 0.001) demonstrated a significant decrease in the rhBMP-2 dose used per level, with major transitions seen in 2018, 2011, and 2013, respectively. In our sample, 129 complications following spinal arthrodesis were noted. A significant relation between rhBMP-2 size and complication rates (χ²= 73.73, P = 0.0029) was noted. rhBMP-2 dosage per level was a predictor of complication following spinal arthrodesis (odds ratio = 1.302 [1.05-1.55], P < 0.001).

CONCLUSIONS

BMP is an effective compound in fusing adjacent spine segments. However, it carries some regional complications. We demonstrate a decreasing trend in the dose/vertebral level. A decrease rhBMP-2 dose per level correlated with a decrease in complication rates.

Improved Posterolateral Lumbar Spinal Fusion Using a Biomimetic, Nanocomposite Scaffold Augmented by Autologous Platelet-Rich Plasma

Remodeling of the human bony skeleton is constantly occurring with up to 10% annual bone volume turnover from osteoclastic and osteoblastic activity. A shift toward resorption can result in osteoporosis and pathologic fractures, while a shift toward deposition is required after traumatic, or surgical injury. Spinal fusion represents one such state, requiring a substantial regenerative response to immobilize adjacent vertebrae through bony union. Autologous bone grafts were used extensively prior to the advent of advanced therapeutics incorporating exogenous growth factors and biomaterials. Besides cost constraints, these applications have demonstrated patient safety concerns. This study evaluated the regenerative ability of a nanostructured, magnesium-doped, hydroxyapatite/type I collagen scaffold (MHA/Coll) augmented by autologous platelet-rich plasma (PRP) in an orthotopic model of posterolateral lumbar spinal fusion. After bilateral decortication, rabbits received either the scaffold alone (Group 1) or scaffold with PRP (Group 2) to the anatomic right side. Bone regeneration and fusion success compared to internal control were assessed by DynaCT with 3-D reconstruction at 2, 4, and 6 weeks postoperatively followed by comparative osteogenic gene expression and representative histopathology. Both groups formed significantly more new bone volume than control, and Group 2 subjects produced significantly more trabecular and cortical bone than Group 1 subjects. Successful fusion was seen in one Group 1 animal (12.5%) and 6/8 Group 2 animals (75%). This enhanced effect by autologous PRP treatment appears to occur via astounding upregulation of key osteogenic genes. Both groups demonstrated significant gene upregulation compared to vertebral bone controls for all genes. Group 1 averaged 2.21-fold upregulation of RUNX2 gene, 3.20-fold upregulation of SPARC gene, and 3.67-fold upregulation of SPP1 gene. Depending on anatomical subgroup (cranial, mid, caudal scaffold portions), Group 2 had significantly higher average expression of all genes than both control and Group 1–RUNX2 (8.23–19.74 fold), SPARC (18.67–55.44 fold), and SPP1 (46.09–90.65 fold). Our data collectively demonstrate the osteoinductive nature of a nanostructured MHA/Coll scaffold, a beneficial effect of augmentation with autologous PRP, and an ability to achieve clinical fusion when applied together in an orthotopic model. This has implications both for future study and biomedical innovation of bone-forming therapeutics.

Single-level fusion without decompression for high-grade spondylolithesis in adolescents: a novel surgical strategy

PURPOSE

There is no consensus on the optimal surgical treatment for high-grade spondylolisthesis (HGS) in adolescents. The purpose of this study was to assess the radiographic and clinical outcomes of a novel surgical approach to HGS consisting of a single-level anterior reduction, placement of a lordotic cage, and circumferential fixation without decompression.

METHODS

This was a retrospective consecutive case series of 11 adolescents who underwent anterior reduction through placement of a lordotic cage followed by posterior fusion using pedicle screws and rods confined to L5-S1. Radiographic data included slip percentage, slip angle, lumbar lordosis, and pelvic sagittal parameters assessed at clinical visits preoperatively and at 2 years postoperatively. A telephone survey was conducted to obtain current information about function, activity level, work status, and retrograde ejaculation.

RESULTS

Patients were followed for an average of 7.8 years (range 2-16). Mean age was 15.5 years (range 12-19). The mean percent slip corrected from 55 to 18%. The average slip angle was + 17.1° preoperatively and - 14.1° at final assessment (average correction of 20.7°). Thirty-six percent (4/11) of patients improved by three Meyerding grades and an additional 55% (6/11) improved by two grades. Complications included one instance each of superficial infection, wound dehiscence, and transient neuralgia. There were no cases of instrumentation failure, cage subsidence, pseudoarthrosis, or retrograde ejaculation. Radiographic evidence of fusion was observed in all cases.

CONCLUSION

Single-level anterior reduction and circumferential fusion without decompression appears to be a safe and effective alternative for the surgical treatment of pediatric HGS.

LEVEL OF EVIDENCE

IV.

Iatrogenic effects of radical cancer surgery on male fertility

Iatrogenic causes of male infertility can include medications, chemotherapy, radiation, and surgery. In this review, we discuss commonly performed urologic cancer surgeries and nonurologic surgeries that harbor a high risk of iatrogenic infertility. These include radical prostatectomy, radical cystectomy, retroperitoneal lymph node dissection, pelvic colon surgery, and anterior spine surgery. In addition, we review the anatomy and surgical strategies that help to reduce the risks of infertility. With an increase in life expectancy and improvements in fertility preservation, it is important to properly counsel patients about the risks of infertility and provide options for fertility preservation before surgery.

Evaluation of the optimal dosage of BMP-9 through the comparison of bone regeneration induced by BMP-9 versus BMP-2 using an injectable microparticle embedded thermosensitive polymeric carrier in a rat cranial defect model

Bone morphogenetic proteins (BMPs) are well known as enhancers and facilitators of osteogenesis during bone regeneration. The use of recombinant BMP-2 (rhBMP-2) in bone defect healing has drawbacks, which has driven the scouting for alternatives, such as recombinant BMP-9 (rhBMP-9), to provide comparable new bone formation. However, the dosage of rhBMP-9 is quintessential for the facilitation of adequate bone defect healing. Therefore, this study has been designed to evaluate the optimal dosage of BMP-9 by comparing the bone defect healing induced by rhBMP-9 over rhBMP-2. The chitosan (CS) microparticles (MPs), coated with BMPs, were embedded in a thermoresponsive methylcellulose (MC) and calcium alginate (Alg) based injectable delivery system containing a dosage of either 0.5 μg or 1.5 μg of the respective rhBMP per bone defect. A 5 mm critical-sized cranial defect rat model has been used in this study, and bone tissues were harvested at eight weeks post-surgery. The standard tools for comparing the new bone regeneration included micro computerized tomography (micro-CT) and histological analysis. A novel perspective of analyzing the new bone quality and crystallinity was employed by using Raman spectroscopy, along with its elastic modulus quantified through Atomic Force Microscopy (AFM). Results showed that the rhBMP-9 administered at a dosage of 1.5 μg per bone defect, using this delivery system, can adequately facilitate the bone void filling with ample new bone mineralization and crystallinity as compared to rhBMP-2, thus approving the hypothesis for a viable rhBMP-2 alternative.

Impact of surgeon rhBMP-2 cost awareness on complication rates and health system costs for spinal arthrodesis

OBJECTIVE

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is used in spinal arthrodesis procedures to enhance bony fusion. Research has suggested that it is the most cost-effective fusion enhancer, but there are significant upfront costs for the healthcare system. The primary objective of this study was to determine whether intraoperative dosing and corresponding costs changed with surgeon cost awareness. The secondary objective was to describe surgical complications before and after surgeon awareness of rhBMP-2 cost.

METHODS

A retrospective medical record review was conducted to identify patients who underwent spinal arthrodesis procedures performed by a single surgeon, supplemented with rhBMP-2, from June 2016 to June 2018. Collected data included rhBMP-2 dosage, rhBMP-2 list price, and surgical complications. Expected Medicare reimbursement was calculated. Data were analyzed before and after surgeon awareness of rhBMP-2 cost.

RESULTS

Forty-eight procedures were performed using rhBMP-2, 16 before and 32 after surgeon cost awareness. Prior to cost awareness, the most frequent rhBMP-2 dosage level was x-small (38.9%, n = 7), followed by large (27.8%, n = 5) and small (22.2%, n = 4). After cost awareness, the most frequent rhBMP-2 dosage was xx-small (56.8%, n = 21), followed by x-small (21.6%, n = 8) and large (13.5%, n = 5). The rhBMP-2 average cost per surgery was $4116.56 prior to surgeon cost awareness versus $2268.38 after. Two complications were observed in the pre-cost awareness surgical group; 2 complications were observed in the post-cost awareness surgical group.

CONCLUSIONS

Surgeon awareness of rhBMP-2 cost resulted in use of smaller rhBMP-2 doses, decreased rhBMP-2 cost per surgery, and decreased overall hospital admission charges, without a detectable increase in surgical complications.

Controlled Osteogenic Differentiation of Human Mesenchymal Stem Cells Using Dexamethasone-Loaded Light-Responsive Microgels

Human mesenchymal stem cells (hMSCs), which have the ability to differentiate into osteoblasts, show promise for bone tissue engineering and bone defect treatment. While there are a number of approaches currently available to accomplish this, e.g., utilizing biodegradable materials loaded with the synthetic glucocorticoid osteogenic inducer dexamethasone (DEX), there are still many disadvantages with the current technologies. Here, we generated light-responsive microgels that we showed are capable of loading and releasing DEX in a light-triggered fashion, with the released DEX being able to induce hMSC differentiation into osteoblasts. Specifically, light-responsive poly(N-isopropylacrylamide-co-nitrobenzyl methacrylate) (pNIPAm-co-NBMA) microgels were synthesized via free radical precipitation polymerization and their size, morphology, and chemical composition were characterized. We then went on to show that the microgels could be loaded with DEX (via what we think are hydrophobic interactions) and released upon exposure to UV light. We went on to show that the DEX released from the microgels was still capable of inducing osteogenic differentiation of hMSCs using an alamarBlue assay and normalized alkaline phosphatase (ALP) activity assay. We also investigated how hMSC differentiation was impacted by intermittent DEX released from UV-exposed microgels. Finally, we confirmed that the microgels themselves were not cytotoxic to hMSCs. Taken together, the DEX-loaded light-responsive microgels reported here may find a use for niche clinical applications, e.g., bone tissue repair.

Characterizing the autonomic neural connections between the abdominal aortic and superior hypogastric plexuses: A multimodal neuroanatomical study

The aortic plexus serves as the primary gateway for sympathetic fibers innervating the pelvic viscera. Damage to this plexus and/or its associated branches can lead to an assortment of neurogenic complications such as bladder dysregulation or retrograde ejaculation. The neuroanatomy of this autonomic plexus has only recently been clarified in humans; as such, the precise function of its constituent fibers is still not clear. Further study into the functional neuroanatomy of the aortic plexus could help refine nerve-sparing surgical procedures that risk debilitating neurogenic complications, while also advancing understanding of peripheral sympathetic circuitry. To this end, the current study employed an in vivo electrostimulation paradigm in a porcine model, in combination with lipophilic neuronal tracing experiments in fixed, post-mortem human tissues, to further characterize the functional neuroanatomy of the aortic plexus. Electrostimulation results demonstrated that caudal lumbar splanchnic nerves provide primary control over the porcine bladder neck in comparison to other constituent fibers within the aortic plexus. Ex vivo human data revealed that the prehypogastric ganglion contains a significant number of neurons projecting to the superior hypogastric plexus, and that these neurons are arranged in a topographic manner within the ganglion. Altogether, these findings suggest that a pivotal sympathetic pathway mediating bladder neck contraction courses through the caudal lumbar splanchnic nerves, prehypogastric and inferior mesenteric ganglia and superior hypogastric plexus.

Technique for Exposing Lumbar Discs in Anterior Approach Using Steinmann Wires: Arthroplasties or Arthrodesis

BACKGROUND

Due to increasing longevity, the incidence of degenerative lumbar disc diseases has increased, and surgical treatment is often necessary. In this context, the anterior approach becomes an important technique. However, one of the main limitations of this method is the need for dedicated retractors, which requires larger incisions for its positioning and increases the cost of the procedure. The objective of the present study was to describe a technique for retracting abdominal structures by anterior approaches to the lumbar spine using Steinmann wires.

METHODS

This manuscript consists of a technique description of anterior approach for lumbar spine.

RESULTS

Surgical treatment of degenerative lumbar spine disease is often necessary when the patients have symptoms refractory to conservative treatments. Many of them will be candidates for surgical treatment with anterior approach, either for arthrodesis/anterior lumbar interbody fusion or arthroplasty. Small incisions are performed for positioning the modified Langenbeck retractors and the Steinmann wires. These retractors are easily positioned and provide good exposure of the lumbar discs making it possible to implant appropriate cages for restoring the necessary height, lordosis, and sagittal balance.

CONCLUSIONS

The technique described is safe, inexpensive, and reproducible. Simple and easily accessible instruments are required in most hospital complexes.

State of the art advances in minimally invasive surgery for adult spinal deformity

Adult spinal deformity (ASD) can be associated with substantial suffering due to pain and disability. Surgical intervention for achieving neural decompression and restoring physiological spinal alignment has shown to result in significant improvement in pain and disability through patient-reported outcomes. Traditional open approaches involving posterior osteotomy techniques and instrumentation are effective based on clinical outcomes but associated with high complication rates, even in the hands of the most experienced surgeons. Minimally invasive techniques may offer benefit while decreasing associated morbidity. Minimally invasive surgery (MIS) for ASD has evolved over the past 20 years, driven by improved understanding of open procedures along with novel technique development and technologic advancements. Early efforts were hindered due to suboptimal outcomes resulting from high pseudarthrosis, inadequate correction, and fixation failure rates. To address this, multi-center collaborative groups have been established to study large numbers of ASD patients which have been vital to understanding optimal patient selection and individualized management strategies. Different MIS decision-making algorithms have been described to better define appropriate candidates and interbody selection approaches in ASD. The purpose of this state of the review is to describe the evolution of MIS surgery for adult deformity with emphasis on landmark papers, and to discuss specific MIS technology for ASD, including percutaneous pedicle screw instrumentation, hyperlordotic grafts, three-dimensional navigation, and robotics.

Lumbar Interbody Fusion: Techniques, Pearls and Pitfalls

Lumbar interbody fusion (LIF) is an effective and popular surgical procedure for the management of various spinal pathologies, especially degenerative diseases. Currently, LIF can be performed with posterior, transforaminal, anterior, and lateral approaches by open surgery or minimally invasive surgery (MIS). Each technique has its own advantages and disadvantages. In general, posterior LIF is a well-established procedure with good fusion rates and low complication rates but is limited by the possibility of iatrogenic injury to the neural structures and paraspinal muscles. Transforaminal LIF is frequently performed using an MIS technique and has an advantage of reducing these iatrogenic injuries. Anterior LIF (ALIF) can restore the disk height and sagittal alignment but has inherent approach-related challenges such as visceral and vascular complications. Lateral LIF and oblique LIF are performed using an MIS technique and have shown postoperative outcomes similar to ALIF; however, these approaches carry a risk of injury to psoas, lumbar plexus, and vascular structures. Herein, we provide a detailed description of the surgical procedures of each LIF technique. We shall then consider the pearls and pitfalls, as well as propose surgical indications and contraindications based on the available evidence in the literatures.

Bone Morphogenetic Protein-2 in Development and Bone Homeostasis

Bone morphogenetic proteins (BMPs) are multi-functional growth factors belonging to the Transforming Growth Factor-Beta (TGF-β) superfamily. These proteins are essential to many developmental processes, including cardiogenesis, neurogenesis, and osteogenesis. Specifically, within the BMP family, Bone Morphogenetic Protein-2 (BMP-2) was the first BMP to be characterized and has been well-studied. BMP-2 has important roles during embryonic development, as well as bone remodeling and homeostasis in adulthood. Some of its specific functions include digit formation and activating osteogenic genes, such as Runt-Related Transcription Factor 2 (RUNX2). Because of its diverse functions and osteogenic potential, the Food and Drug Administration (FDA) approved usage of recombinant human BMP-2 (rhBMP-2) during spinal fusion surgery, tibial shaft repair, and maxillary sinus reconstructive surgery. However, shortly after initial injections of rhBMP-2, several adverse complications were reported, and alternative therapeutics have been developed to limit these side-effects. As the clinical application of BMP-2 is largely implicated in bone, we focus primarily on its role in bone. However, we also describe briefly the role of BMP-2 in development. We then focus on the structure of BMP-2, its activation and regulation signaling pathways, BMP-2 clinical applications, and limitations of using BMP-2 as a therapeutic. Further, this review explores other potential treatments that may be useful in treating bone disorders.

The impact of obesity on perioperative complications in patients undergoing anterior lumbar interbody fusion

OBJECTIVE

Anterior approaches to the lumbar spine provide wide exposure that facilitates placement of large grafts with high fusion rates. There are limited data on the effects of obesity on perioperative complications.

METHODS

Data from consecutive patients undergoing anterior lumbar interbody fusion (ALIF) from 2007 to 2016 at a single academic center were analyzed. The primary outcome was any perioperative complication. Complications were divided into those occurring intraoperatively and those occurring postoperatively. Multivariate logistic regression was used to assess the association of obesity and other variables with these complications. An estimation table was used to identify a body mass index (BMI) threshold associated with increased risk of postoperative complication.

RESULTS

A total of 938 patients were identified, and the mean age was 57 years; 511 were females (54.5%). The mean BMI was 28.7 kg/m2, with 354 (37.7%) patients classified as obese (BMI ≥ 30 kg/m2). Forty patients (4.3%) underwent a lateral transthoracic approach, while the remaining 898 (95.7%) underwent a transabdominal retroperitoneal approach. Among patients undergoing transabdominal retroperitoneal ALIF, complication rates were higher for obese patients than for nonobese patients (37.0% vs 28.7%, p = 0.010), a difference that was driven primarily by postoperative complications (36.1% vs 26.0%, p = 0.001) rather than intraoperative complications (3.2% vs 4.3%, p = 0.416). Obese patients had higher rates of ileus (11.7% vs 7.2%, p = 0.020), wound complications (11.4% vs 3.4%, p < 0.001), and urinary tract infections (UTI) (5.0% vs 2.5%, p = 0.049). In a multivariate model, age, obesity, and number of ALIF levels fused were associated with an increased risk of postoperative complication. An estimation table including 19 candidate cut-points, odds ratios, and adjusted p values found a BMI ≥ 31 kg/m2 to have the highest association with postoperative complication (p = 0.012).

CONCLUSIONS

Obesity is associated with increased postoperative complications in ALIF, including ileus, wound complications, and UTI. ALIF is a safe and effective procedure. However, patients with a BMI ≥ 31 kg/m2 should be counseled on their increased risks and warrant careful preoperative medical optimization and close monitoring in the postoperative setting.

Bone Morphogenetic Protein-2 Conjugated to Quantum Dot®s is Biologically Functional

Quantum Dot^®s (QDot^®s) are novel, semi-conductive nanostructures that emit a certain fluorescence when excited by specific wavelengths. QDot^®s are more photostable, brighter, and photobleach less than other fluorescent dyes. These characteristics give them the potential to be used in many biological applications. The shells of QDot^®s are coated with functional groups, such as carboxylate and organic groups, allowing them to couple to peptides/proteins and be used for real-time imaging and high-resolution microscopy. Here, we utilize Quantum Dot^®s and Bone Morphogenetic Protein-2 (BMP-2) to create a BMP-2-QDot^®s conjugate. BMP-2 is a growth factor that drives many processes such as cardiogenesis, neural growth, and osteogenesis. Despite its numerous roles, the trafficking and uptake of BMP-2 into cells is not well-established, especially during progression of diseases. The results presented here demonstrate for the first time a fluorescent BMP-2 analog that binds to the BMP-receptors (BMPRs), remains biologically active, and is stable for long time periods. Previous attempts to develop a biological BMP-2 analog with Fluorescein isothiocyanate (FITC) or nanodiamonds lacked data on the analog’s stability. Furthermore, these analogs did not address whether they can signal within the cell by binding to the BMPRs or were mediated by non-stable conjugates.

Overview of Minimally Invasive Spine Surgery

Minimally invasive spine surgery (MISS) has continued to evolve over the past few decades, with significant advancements in technology and technical skills. From endonasal cervical approaches to extreme lateral lumbar interbody fusions, MISS has showcased its usefulness across all practice areas of the spine, with unique points of access to avoid pertinent neurovascular structures. Adult spine deformity has also recognized the importance of minimally invasive techniques in its ability to limit complications and to provide adequate sagittal alignment correction and improvements in patients' functional status. Although MISS has continued to make significant progress clinically, consideration must also be given to its economic impact and the learning curve surgeons experience in adding these procedures to their armamentarium. This review examines current innovations in MISS, as well as the economic impact and future directions of the field.

Bovine bone particulates containing bone anabolic factors as a potential xenogenic bone graft substitute

Background

Alternative grafts are needed to improve the healing of bone non-union. Here, we assessed a bovine bone product which retains the inorganic and organic components of bone, as an alternative bone graft.

Methods

Bovine bone matrix proteins (BBMPs) were isolated from bovine bone particulates (BBPs) and tested in vitro. Primary rat osteoblast viability, differentiation, and mineralisation were assessed with alamarBlue®, real-time PCR, and von Kossa staining assays, respectively. Osteoclast formation was assessed in primary murine bone marrow cultures with TRAP staining.

Human osteoblast growth and differentiation in the presence of BBPs was evaluated in 3D collagen gels in vitro using alamarBlue® and real-time PCR, respectively. The efficacy of BBPs as an alternative bone graft was tested in a rat critical-size calvarial defect model, with histology scored at 4 and 12 weeks post-surgery.

Results

In vitro, the highest concentration of BBMPs increased mineral deposition five-fold compared to the untreated control group (P < 0.05); enhanced the expression of key osteoblast genes encoding for RUNX2, alkaline phosphatase, and osteocalcin (P < 0.05); and decreased osteoclast formation three-fold, compared to the untreated control group (P < 0.05).

However, the BBPs had no effect on primary human osteoblasts in vitro, and in vivo, no difference was found in healing between the BBP-treated group and the untreated control group.

Conclusions

Overall, despite the positive effects of the BBMPs on the cells of the bone, the bovine bone product as a whole did not enhance bone healing. Finding a way to harness the positive effect of these BBMPs would provide a clear benefit for healing bone non-union.

Sexual activity after spine surgery: a systematic review

INTRODUCTION

Sexual function is an important determinant of quality of life, and factors such as surgical approach, performance of fusion, neurological function and residual pain can affect it after spine surgery. Our aim was to perform a systematic review to collate evidence regarding the impact of spine surgery on sexual function.

METHODS

A systematic review of studies reporting measures of sexual function, and incidence of adverse sexual outcomes (retrograde ejaculation) after major spine surgery was done, regardless of spinal location. Pubmed (MEDLINE) and Google Scholar databases were queried using the following search words "Sex", "Sex life", "Sexual function", "Sexual activity", "retrograde ejaculation", "Spine", "Spine surgery", "Lumbar surgery", "Lumbar fusion", "cervical spine", "cervical fusion", "Spinal deformity", "scoliosis" and "Decompression". All articles published between 1997 and 2017 were retrieved from the database. A total of 81 studies were included in the final review.

RESULTS

Majority of the studies were retrospective case series and were low quality (Level IV) in evidence. Anterior lumbar approaches were associated with a higher incidence of retrograde ejaculation, especially with the utilization of transperitoneal laparoscopic approach. There is inconclusive evidence on the preferred sexual position following fusion, and also on the impact of BMP-2 usage on retrograde ejaculation/sexual dysfunction.

CONCLUSION

Despite limited evidence from high-quality articles, there is a general trend towards improvement of sexual activity and function after spine surgery. Future studies incorporating specific assessments of sexual activity will be required to address this important determinant of quality of life so that appropriate pre-operative counselling can be done by providers. These slides can be retrieved under Electronic Supplementary Material.

An awake, minimally-invasive, fully-endoscopic surgical technique for treating lumbar radiculopathy secondary to heterotopic foraminal bone formation after a minimally invasive transforaminal lumbar interbody fusion with BMP: technical note

One complication associated with recombinant human bone morphogenetic protein (rhBMP-2) use in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is heterotopic bone growth at the neural foramen which results in the compression of neural structures. Here we present an awake, minimally invasive surgical approach for treating the radiculopathy that results from this excessive bone growth in the foramen. A 42-year-old male underwent a lumbar 4-sacral 1 MIS-TLIF by another surgeon. He did well in the initial postoperative period, but he began to note right leg pain and numbness in an L5 dermatomal pattern. The pain continued for 2 years despite interventional pain management, and he began to note left foot dorsiflexion weakness. An electromyography (EMG) showed a left L5 radiculopathy and a CT Lumbar spine demonstrated excessive bone growth in the right L4-5 neural foramen. The patient underwent an awake, endoscopic foraminotomy procedure utilizing a blunt tipped manual shaver drill system. The patient's radicular symptoms improved immediately, and he remained asymptomatic at the 1 year follow up. Heterotopic foraminal bone growth is one potential complication of rhBMP-2 use in the MIS-TLIF procedure. The endoscopic procedure described here is a minimally invasive surgical option that can be performed in an awake patient and is suggested a unique salvage or rescue procedure to be considered for the treatment of this potential rhBMP-2 complication.

Forces associated with launch into space do not impact bone fracture healing

Segmental bone defects (SBDs) secondary to trauma invariably result in a prolonged recovery with an extended period of limited weight bearing on the affected limb. Soldiers sustaining blast injuries and civilians sustaining high energy trauma typify such a clinical scenario. These patients frequently sustain composite injuries with SBDs in concert with extensive soft tissue damage. For soft tissue injury resolution and skeletal reconstruction a patient may experience limited weight bearing for upwards of 6 months. Many small animal investigations have evaluated interventions for SBDs. While providing foundational information regarding the treatment of bone defects, these models do not simulate limited weight bearing conditions after injury. For example, mice ambulate immediately following anesthetic recovery, and in most cases are normally ambulating within 1-3 days post-surgery. Thus, investigations that combine disuse with bone healing may better test novel bone healing strategies. To remove weight bearing, we have designed a SBD rodent healing study in microgravity (µG) on the International Space Station (ISS) for the Rodent Research-4 (RR-4) Mission, which launched February 19, 2017 on SpaceX CRS-10 (Commercial Resupply Services). In preparation for this mission, we conducted an end-to-end mission simulation consisting of surgical infliction of SBD followed by launch simulation and hindlimb unloading (HLU) studies. In brief, a 2 mm defect was created in the femur of 10 week-old C57BL6/J male mice (n = 9-10/group). Three days after surgery, 6 groups of mice were treated as follows: 1) Vivarium Control (maintained continuously in standard cages); 2) Launch Negative Control (placed in the same spaceflight-like hardware as the Launch Positive Control group but were not subjected to launch simulation conditions); 3) Launch Positive Control (placed in spaceflight-like hardware and also subjected to vibration followed by centrifugation); 4) Launch Positive Experimental (identical to Launch Positive Control group, but placed in qualified spaceflight hardware); 5) Hindlimb Unloaded (HLU, were subjected to HLU immediately after launch simulation tests to simulate unloading in spaceflight); and 6) HLU Control (single housed in identical HLU cages but not suspended). Mice were euthanized 28 days after launch simulation and bone healing was examined via micro-Computed Tomography (µCT). These studies demonstrated that the mice post-surgery can tolerate launch conditions. Additionally, forces and vibrations associated with launch did not impact bone healing (p = .3). However, HLU resulted in a 52.5% reduction in total callus volume compared to HLU Controls (p = .0003). Taken together, these findings suggest that mice having a femoral SBD surgery tolerated the vibration and hypergravity associated with launch, and that launch simulation itself did not impact bone healing, but that the prolonged lack of weight bearing associated with HLU did impair bone healing. Based on these findings, we proceeded with testing the efficacy of FDA approved and novel SBD therapies using the unique spaceflight environment as a novel unloading model on SpaceX CRS-10.

Efficacy of Escherichia coli-derived recombinant human bone morphogenetic protein-2 in posterolateral lumbar fusion: an open, active-controlled, randomized, multicenter trial

BACKGROUND CONTEXT

The efficacy and safety of recombinant human bone morphogenetic protein-2 (rhBMP-2) as a bone graft substitute in spinal fusion has been widely researched. However, no study of the efficacy and safety of Escherichia coli-derived rhBMP-2 (E.BMP-2) with a hydroxyapatite (HA) carrier has been proposed.

PURPOSE

This study aimed to compare the efficacy and safety of fusion materials between E.BMP-2 and autogenous iliac bone graft in posterolateral fusion (PLF).

STUDY DESIGN/SETTING

An open, active-controlled, randomized, multicenter trial was carried out.

PATIENT SAMPLE

This study included 93 patients who underwent single-level lumbar or lumbosacral PLF.

OUTCOME MEASURES

The primary outcome measure was computed tomography (CT)-based fusion rate at 12 and 24 weeks. Secondary outcome measures were fusion grade by radiographs and CT at 12 and 24 weeks and changes in Oswestry Disability Index (ODI), Short Form-36 (SF-36) Health Survey, and visual analogue scale (VAS).

METHODS

Patients who underwent 1-level PLF (between L1 and S1) for severe spinal stenosis or grade 1 spondylolisthesis were randomized to receive E.BMP-2 with an HA carrier (E.BMP-2 group) or autogenous iliac bone graft (AIBG group). Thin-section CT (<2 mm), VAS, ODI, and SF-36 were obtained pre- and postoperatively at 12 and 24 weeks. Outcome measures were compared between the groups.

RESULTS

A total of 100 patients were enrolled in this trial. Among them, 93 patients underwent planned surgery. Preoperative demographic and clinical data showed no difference between groups. CT-based fusion rates were 100.0% (41/41) for the E.BMP-2 group and 90.2% (46/51) for the AIBG group (p=.062) at 12 weeks and 100.0% (41/41) and 94.1% (48/51) (p=.251) at 24 weeks, respectively. Fusion grade based on radiographs and CT showed non-inferiority of the E.BMP-2 group compared with the AIBG group. All clinical parameters improved postoperatively. However, there was no difference in changes in VAS, ODI, or SF-36 between the groups. No serious adverse event related to E.BMP-2 was found.

CONCLUSIONS

The fusion rate of E.BMP-2 was comparable with that of AIBG following PLF. Good clinical efficacy and safety of E.BMP-2 in spinal fusion were also revealed. It was also suggested that HA shows suitability as a carrier for E.BMP-2. Thus, E.BMP-2 with an HA carrier can be an alternative bone graft material in spinal fusion.

Neuroforaminal Bone Growth Following Minimally Invasive Transforaminal Lumbar Interbody Fusion With BMP: A Computed Tomographic Analysis

STUDY DESIGN

Computed tomographic analysis.

OBJECTIVE

To identify radiographic patterns of symptomatic neuroforaminal bone growth (NFB) in patients who have undergone a single-level minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) augmented with bone morphogenetic proteins (BMP) utilizing computed tomography (CT).

SUMMARY OF BACKGROUND DATA

BMP induces osteoblast differentiation leading to new bone formation. The association of BMP utilization and heterotopic bone formation after an MIS-TLIF has been described. However, studies have been limited in their patient population and details regarding diagnosis and treatment of NFB.

MATERIALS AND METHODS

Postoperative CT scans of the symptomatic and asymptomatic patients were analyzed to identify patterns of heterotopic bone growth on axial and sagittal views. The area of bone growth at the disk level, lateral recess, adjacent foramen, and retrovertebral area were measured. Mann-Whitney U test was used to compare the areas of bone growth between cohorts.

RESULTS

Postoperative CT images between 18 symptomatic and 13 asymptomatic patients were compared. On axial views, the symptomatic patients demonstrated greater areas of bone growth at the disk level (164.0±92.4 vs. 77.0±104.9 mm), and lateral recess (69.6±70.5 and 5.9±12.5 mm) as well as in the total cross-sectional area (290.3±162.1 vs. 119.4±115.6 mm). On sagittal imaging, the mean bone growth at the subarticular level (148.7±185.1 vs. 35.8±37.4 mm) and the total cross-sectional area (298.4±324.4 vs. 85.8±76.3 mm) were greater in symptomatic patients (P<0.01). Amount of BMP utilized and operative levels were no different between cohorts.

CONCLUSIONS

The findings of the present study suggest that an anatomic association exists between recalcitrant postoperative radiculopathy and NFB following an MIS-TLIF with BMP. Increased total bone growth as measured on serial axial and sagittal sections was associated with postoperative radiculopathy. The association between radiculopathy and the extension of BMP-induced bone growth toward the traversing nerve root appeared the most significant.

Local application of lactoferrin promotes bone regeneration in a rat critical-sized calvarial defect model as demonstrated by micro-CT and histological analysis

Lactoferrin is a multifunctional glycoprotein with therapeutic potential for bone tissue engineering. The aim of this study was to assess the efficacy of local application of lactoferrin on bone regeneration. Five‐millimetre critical‐sized defects were created over the right parietal bone in 64 Sprague–Dawley rats. The rats were randomized into four groups: group 1 (n  =  20) had empty defects; group 2 (n  =  20) had defects grafted with collagen gels (3 mg/ml); group 3 (n  =  20) had defects grafted with collagen gels impregnated with bovine lactoferrin (10 μg/gel); and group 4 (n  =  4) had sham surgeries (skin and periosteal incisions only). The rats were sacrificed at 4 or 12 weeks post‐operatively, and the calvaria were excised and evaluated with micro‐CT (Skyscan 1172) followed by histology. The bone volume fraction (BV/TV) was higher in lactoferrin‐treated animals at both timepoints, with groups 1, 2, 3 and 4 measuring 10.5  ±  1.1%, 8.6  ±  1.4%, 16.5  ±  0.6% and 24.27  ±  2.6%, respectively, at 4 weeks (P  <  0.05); and 12.2  ±  1.3%, 13.6  ±  1.5%, 21.9  ±  1.2% and 29.3  ±  0.8%, respectively, at 12 weeks (P  <  0.05). Histological analysis revealed that the newly formed bone within the calvarial defects of all groups was a mixture of woven and lamellar bone, with more bone in the group treated with lactoferrin at both timepoints. Our study demonstrated that local application of lactoferrin significantly increased bone regeneration in a rat critical‐sized calvarial defect model. The profound effect of lactoferrin on bone regeneration has therapeutic potential to improve the poor clinical outcomes associated with bony non‐union. LF In Vivo JTERM Authors Contributions. Copyright © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons, Ltd.

A Retrospective Analysis of Complications Associated With Bone Morphogenetic Protein 2 in Anterior Lumbar Interbody Fusion

STUDY DESIGN

Retrospective review.

OBJECTIVE

The aim of our study was to quantify the frequency of complications associated with recombinant human bone morphogenetic protein 2 (rhBMP-2) use in anterior lumbar interbody fusion (ALIF).

METHODS

The orthopedic subset of the Medicare database (PearlDiver) was queried for this retrospective cohort study using International Statistical Classification of Diseases 9 (ICD-9) and Current Procedure Terminology (CPT) codes for ALIF procedures with and without rhBMP-2 between 2005 and 2010. Frequencies of complications and reoperations were then identified within 1 year from the index procedure. Complications included reoperations, pulmonary embolus, deep vein thrombosis, myocardial infarction, nerve-related complications, incision and drainage procedures, wound, sepsis, pneumonia, urinary tract infections, respiratory, heterotopic ossification, retrograde ejaculation, radiculopathy, and other medical complications. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the statistical significance.

RESULTS

We identified a total of 41 865 patients who had an ALIF procedure. A total of 14 384 patients received rhBMP-2 while 27 481 did not. Overall, 6016 (41.8%) complications within 1 year from surgery were noted within the group who received rhBMP-2 and 12 950 (47.1%) complications within 1 year from surgery were recorded in those who did not receive rhBMP-2 (OR = 0.81, CI = 0.77-0.84). Overall, exposure to rhBMP-2 was associated with significantly decreased odds of complications with exception to reoperation rates (0.9% rhBMP-2 vs 1.0% no rhBMP-2; OR = 0.88, CI = 0.71-1.09) and radiculopathy (4.4% rhBMP-2 vs 4.3% no rhBMP-2; OR = 1.02, CI = 0.93-1.13).

CONCLUSIONS

The use of rhBMP-2 in patients undergoing ALIF procedure was associated with a significantly decreased rate of complications. Further studies are needed to elucidate a true incidence of complication.

Formulation, Delivery and Stability of Bone Morphogenetic Proteins for Effective Bone Regeneration

Bone morphogenetic proteins (BMPs) are responsible for bone formation during embryogenesis and bone regeneration and remodeling. The osteoinductive action of BMPs, especially BMP-2 and BMP-7, has led to their use in a range of insurmountable treatments where intervention is required for effective bone regeneration. Introduction of BMP products to the market, however, was not without reports of multiple complications and side effects. Aiming for optimization of the therapeutic efficacy and safety, efforts have been focused on improving the delivery of BMPs to lower the administered dose, localize the protein, and prolong its retention time at the site of action. A major challenge with these efforts is that the protein stability should be maintained. With this review we attempt to shed light on how the stability of BMPs can be affected in the formulation and delivery processes. We first provide a short overview of the current standing of the complications experienced with BMP products. We then discuss the different delivery parameters studied in association with BMPs, and their influence on the efficacy and safety of BMP treatments. In particular, the literature addressing the stability of BMPs and their possible interactions with components of the delivery system as well as their sensitivity to conditions of the formulation process is reviewed. In summary, recent developments in the fields of bioengineering and biopharmaceuticals suggest that a good understanding of the relationship between the formulation/delivery conditions and the stability of growth factors such as BMPs is a prerequisite for a safe and effective treatment.

Complications Associated With Bone Morphogenetic Protein in the Lumbar Spine

Complications associated with the use of recombinant human bone morphogenetic protein in the lumbar spine include retrograde ejaculation, ectopic bone formation, vertebral osteolysis and subsidence, postoperative radiculitis, and hematoma and seroma. These complications are controversial and remain widely debated. This article discusses the reported complications and possible implications for the practicing spine surgeon. Understanding the complications associated with the use of recombinant human bone morphogenetic protein and the associated controversies allows for informed decision making by both the patient and the surgeon. [Orthopedics. 2017; 40(2):e229-e237.].