Lumbar endoscopic spine surgery for persistent genital arousal disorder/genitopelvic dysesthesia resulting from lumbosacral annular tear-induced sacral radiculopathy.

BACKGROUND: Persistent genital arousal disorder/genitopelvic dysesthesia (PGAD/GPD) is characterized by distressing, abnormal genitopelvic sensations, especially unwanted arousal. In a subgroup of patients with PGAD/GPD, cauda equina Tarlov cyst-induced sacral radiculopathy has been reported to trigger the disorder. In our evaluation of lumbosacral magnetic resonance images in patients with PGAD/GPD and suspected sacral radiculopathy, some had no Tarlov cysts but showed lumbosacral disc annular tear pathology. AIM: The aims were 2-fold: (1) to utilize a novel multidisciplinary step-care management algorithm designed to identify a subgroup of patients with PGAD/GPD and lumbosacral annular tear-induced sacral radiculopathy who could benefit from lumbar endoscopic spine surgery (LESS) and (2) to evaluate long-term safety and efficacy of LESS. METHODS: Clinical data were collected on patients with PGAD/GPD who underwent LESS between 2016 and 2020 with at least 1-year follow-up. LESS was indicated because all had lumbosacral annular tear-induced sacral radiculopathy confirmed by our multidisciplinary management algorithm that included the following: step A, a detailed psychosocial and medical history; step B, noninvasive assessments for sacral radiculopathy; step C, targeted diagnostic transforaminal epidural spinal injections resulting in a temporary, clinically significant reduction of PGAD/GPD symptoms; and step D, surgical intervention with LESS and postoperative follow-up. OUTCOMES: Treatment outcome was based on the validated Patient Global Impression of Improvement, measured at postoperative intervals. RESULTS: Our cohort included 15 cisgendered women and 5 cisgendered men (mean ± SD age, 40.3 ± 16.8 years) with PGAD/GPD who fulfilled the criteria of lumbosacral annular tear-induced sacral radiculopathy based on our multidisciplinary management algorithm. Patients were followed for an average of 20 months (range, 12-37) post-LESS. Lumbosacral annular tear pathology was identified at multiple levels, the most common being L4-L5 and L5-S1. Twenty-two LESS procedures were performed in 20 patients. Overall, 80% (16/20) reported improvement on the Patient Global Impression of Improvement; 65% (13/20) reported improvement as much better or very much better. All patients were discharged the same day. There were no surgical complications. CLINICAL IMPLICATIONS: Among the many recognized triggers for PGAD/GPD, this subgroup exhibited lumbosacral annular tear-induced sacral radiculopathy and experienced long-term alleviation of symptoms by LESS. STRENGTHS AND LIMITATIONS: Strengths include long-term post-surgical follow-up and demonstration that LESS effectively treats patients with PGAD/GPD who have lumbosacral annular tear-induced sacral radiculopathy, as established by a multidisciplinary step-care management algorithm. Limitations include the small study cohort and the unavailability of a clinical measure specific for PGAD/GPD. CONCLUSION: LESS is safe and effective in treating patients with PGAD/GPD who are diagnosed with lumbosacral annular tear-induced sacral radiculopathy.

International Society for the Study of Women's Sexual Health (ISSWSH) Review of Epidemiology and Pathophysiology, and a Consensus Nomenclature and Process of Care for the Management of Persistent Genital Arousal Disorder/Genito-Pelvic Dysesthesia (PGAD/GPD).

BACKGROUND: Persistent genital arousal disorder (PGAD), a condition of unwanted, unremitting sensations of genital arousal, is associated with a significant, negative psychosocial impact that may include emotional lability, catastrophization, and suicidal ideation. Despite being first reported in 2001, PGAD remains poorly understood. AIM: To characterize this complex condition more accurately, review the epidemiology and pathophysiology, and provide new nomenclature and guidance for evidence-based management. METHODS: A panel of experts reviewed pertinent literature, discussed research and clinical experience, and used a modified Delphi method to reach consensus concerning nomenclature, etiology, and associated factors. Levels of evidence and grades of recommendation were assigned for diagnosis and treatment. OUTCOMES: The nomenclature of PGAD was broadened to include genito-pelvic dysesthesia (GPD), and a new biopsychosocial diagnostic and treatment algorithm for PGAD/GPD was developed. RESULTS: The panel recognized that the term PGAD does not fully characterize the constellation of GPD symptoms experienced by patients. Therefore, the more inclusive term PGAD/GPD was adopted, which maintains the primacy of the distressing arousal symptoms and acknowledges associated bothersome GPD. While there are diverse biopsychosocial contributors, there is a common underlying neurologic basis attributable to spontaneous intense activity of the genito-pelvic region represented in the somatosensory cortex and its projections. A process of care diagnostic and treatment strategy was developed to guide the clinician, whenever possible, by localizing the symptoms as originating in any of five regions: (i) end organ, (ii) pelvis/perineum, (iii) cauda equina, (iv) spinal cord, and (v) brain. Psychological treatment strategies were considered critical and should be performed in conjunction with medical strategies. Pharmaceutical interventions may be used based on their site and mechanism of action to reduce patients' symptoms and the associated bother and distress. CLINICAL IMPLICATIONS: The process of care for PGAD/GPD uses a personalized, biopsychosocial approach for diagnosis and treatment. STRENGTHS AND LIMITATIONS: Strengths and Limitations: Strengths include characterization of the condition by consensus, analysis, and recommendation of a new nomenclature and a rational basis for diagnosis and treatment. Future investigations into etiology and treatment outcomes are recommended. The main limitations are the dearth of knowledge concerning this condition and that the current literature consists primarily of case reports and expert opinion. CONCLUSION: We provide, for the first time, an expert consensus review of the epidemiology and pathophysiology and the development of a new nomenclature and rational algorithm for management of this extremely distressing sexual health condition that may be more prevalent than previously recognized. Goldstein I, Komisaruk BR, Pukall CF, et al. International Society for the Study of Women's Sexual Health (ISSWSH) Review of Epidemiology and Pathophysiology, and a Consensus Nomenclature and Process of Care for the Management of Persistent Genital Arousal Disorder/Genito-Pelvic Dysesthesia (PGAD/GPD). J Sex Med 2021;18:665-697.

Selective laminectomy for cervical spondylotic myelopathy: a comparative analysis with laminoplasty technique.

INTRODUCTION: The purpose of this study was to evaluate the effectiveness of selective laminectomy compared with laminoplasty for patients with multilevel cervical spondylotic myelopathy (CSM) by evaluating the radiological and clinical outcomes. METHODS: We retrospectively reviewed 67 patients with who underwent posterior laminectomy (LN) or laminoplasty (LP). LN was performed in 32 cases and LP in 35 cases. Radiologically, we evaluated the neutral C2-7 Cobb angle and range of motion (ROM) preoperatively and at final follow-up. Preoperative spinal cord compression and expansion of the spinal cord area postoperatively was evaluated using MRI. Differences in operating time and intraoperative and postoperative bleeding were analyzed. The clinical outcome was analyzed using the neck disability index (NDI) and the visual analog scale (VAS) for neck pain. RESULTS: Surgery was performed on 2.04 segments in the LN group and 4.06 in the LP group. Cobb angle and ROM significantly decreased in the LN group at the final follow-up. No difference was found in the preoperative cord compression ratio or extent of expansion of the spinal cord postoperatively. The laminectomy group had a significantly shorter operation time and less intraoperative and postoperative bleeding. Both groups showed improved NDI, JOA score, and VAS for neck pain after surgery, with no significant differences. CONCLUSION: Selective posterior laminectomy for the treatment of multilevel CSM showed advantages of shorter operation time and less blood loss, without a significant difference in clinical outcome, when compared with laminoplasty. However, postoperative kyphosis and decreased range of motion were limitations of laminectomy.

Complications associated with the initial learning curve of minimally invasive spine surgery: a systematic review.

BACKGROUND: There is an inherently difficult learning curve associated with minimally invasive surgical (MIS) approaches to spinal decompression and fusion. The association between complication rate and the learning curve remains unclear. QUESTIONS/PURPOSES: We performed a systematic review for articles that evaluated the learning curves of MIS procedures for the spine, defined as the change in frequency of complications and length of surgical time as case number increased, for five types of MIS for the spine. METHODS: We conducted a systematic review in the PubMed database using the terms "minimally invasive spine surgery AND complications AND learning curve" followed by a manual citation review of included manuscripts. Clinical outcome and learning curve metrics were categorized for analysis by surgical procedure (MIS lumbar decompression procedures, MIS transforaminal lumbar interbody fusion, percutaneous pedicle screw insertion, laparoscopic anterior lumbar interbody fusion, and MIS cervical procedures). As the most consistent parameters used to evaluate the learning curve were procedure time and complication rate as a function of chronologic case number, our analysis focused on these. The search strategy identified 15 original studies that included 966 minimally invasive procedures. Learning curve parameters were correlated to chronologic procedure number in 14 of these studies. RESULTS: The most common learning curve complication for decompressive procedures was durotomy. For fusion procedures, the most common complications were implant malposition, neural injury, and nonunion. The overall postoperative complication rate was 11% (109 of 966 cases). The learning curve was overcome for operative time and complications as a function of case numbers in 20 to 30 consecutive cases for most techniques discussed within this review. CONCLUSIONS: The quantitative assessment of the procedural learning curve for MIS techniques for the spine remains challenging because the MIS techniques have different learning curves and because they have not been assessed in a consistent manner across studies. Complication rates may be underestimated by the studies we identified because surgeons tend to select patients carefully during the early learning curve period. The field of MIS would benefit from a standardization of study design and collected parameters in future learning curve investigations.

The effect of fatty infiltration, revision surgery, and sex on lumbar multifidus passive mechanical properties.

Purpose: Previous research has demonstrated increased stiffness in the multifidus muscle compared to other paraspinal muscles at the fiber bundle level. We aimed to compare single fiber and fiber bundle passive mechanical properties of multifidus muscle: (1) in 40 patients undergoing primary versus revision surgery and (2) in muscle with mild versus severe fatty infiltration. Methods: The degree of muscle fatty infiltration was graded using the patients' spine magnetic resonance images. Average single fiber and fiber bundle passive mechanical properties across three tests were compared between primary (N = 30) and revision (N = 10) surgery status, between mild and severe fatty infiltration levels, between sexes, and with age from passive stress-strain tests of excised multifidus muscle intraoperative biopsies. Results: At the single fiber level, elastic modulus was unaffected by degree of fatty infiltration or surgery status. Female sex (p = 0.001) and younger age (p = 0.04) were associated with lower multifidus fiber elastic modulus. At the fiber bundle level, which includes connective tissue around fibers, severe fatty infiltration (p = 0.01) and younger age (p = 0.06) were associated with lower elastic modulus. Primary surgery also demonstrated a moderate, but non-significant effect for lower elastic modulus (p = 0.10). Conclusions: Our results demonstrate that female sex is the primary driver for reduced single fiber elastic modulus of the multifidus, while severity of fatty infiltration is the primary driver for reduced elastic modulus at the level of the fiber bundle in individuals with lumbar spine pathology.

MIS TLIF, EndoTLIF, and the Ability of Navigation/Robotics to Enable Spinal Surgery in an Ambulatory Care Setting.

STUDY DESIGN: Technical Report. OBJECTIVE: Performing surgeries in the ambulatory surgery center affords improved efficiencies in terms of cost and speed. However, ambulatory surgery is only successful if complications, re-admissions, and re-operations are avoided. This report describes the San Diego Outpatient Lumbar Fusion Program, a culmination of cumulative incremental improvements in patient selection and patient education, meticulous peri-operative management, minimally invasive techniques together with navigation/robotics. METHODS: Retrospective review of prospectively collected data on 1-2 level minimally invasive transforaminal lumbar interbody fusions (MIS TLIF). RESULTS: Healthy patients (age 72 years old or less, BMI less than 50, ASA 1 or 2) with good social support and reasonable pre-operative function (ODI 50 or less) treated with the MIS TLIF technique can be discharged home in less than 1 midnight with good clinical results. CONCLUSIONS: Relatively young, healthy patients can safely and effectively undergo 1-2 level lumbar fusion surgery in the ASC setting when using contemporary minimally invasive techniques and computer-assisted navigation/robotics.

Advanced Technologies for Outpatient Lumbar Fusion: Barriers and Opportunities.

BACKGROUND: In recent years, there has been increasing interest in outpatient spine surgery. Minimally invasive techniques have created an opportunity for ambulatory lumbar fusion, and these techniques increasingly involve advanced technologies such as navigation and robotics. OBJECTIVE: To explore the barriers, advantages, and future predictions for such technology in the context of outpatient lumbar fusions. METHODS: This is a narrative review of studies examining the advantages, limitations, and cost-effectiveness of navigation and spinal robotics in conjunction with the outcomes and costs of outpatient lumbar fusion. RESULTS: Outpatient lumbar fusion is a growing trend with ample evidence of its safety, favorable patient outcomes, and cost savings. Navigation and spinal robotics are associated with improved instrumentation accuracy and fewer complications, and the long-term cost savings can make these technologies financially practical in the outpatient setting. Future capabilities with robotics will only increase their value. CONCLUSIONS: Advanced technologies such as navigation and robotics are strategic long-term investments in the context of outpatient lumbar fusion. CLINICAL RELEVANCE: The favorable outcomes and costs associated with navigation and robotics will be relevant to any spine surgeon interested in developing an outpatient lumbar fusion program.

The current state of minimally invasive spine surgery.

Minimally invasive surgery for spinal disorders is predicated on the following basic principles: (1) avoid muscle crush injury by self-retaining retractors; (2) do not disrupt tendon attachment sites of key muscles, particularly the origin of the multifidus muscle at the spinous process; (3) use known anatomic neurovascular and muscle compartment planes; and (4) minimize collateral soft-tissue injury by limiting the width of the surgical corridor. The traditional midline posterior approach for lumbar decompression and fusion violates these key principles of minimally invasive surgery. The tendon origin of the multifidus muscle is detached, the surgical corridor is exceedingly wide, and significant muscle crush injury occurs with the use of powerful self-retaining retractors. The combination of these factors leads to well-described changes in muscle physiology and function. Minimally invasive posterior lumbar surgery is performed with table-mounted tubular retractors that focus the surgical dissection to a narrow corridor directly over the surgical target site. The path of the surgical corridor is chosen based on anatomic planes, specifically avoiding injury to the musculotendinous complex and the neurovascular bundle. With these relatively simple modifications in the minimally invasive surgical technique, significant improvements have been achieved in intraoperative blood loss, postoperative pain, and surgical morbidity. However, minimally invasive surgical techniques remains technically demanding, and a significant complication rate has been reported during a surgeon's initial learning curve for the procedures. Improvements in surgeon training along with long-term prospective studies will be needed for advancements in this area of spine surgery.

The History of Endoscopic Posterior Lumbar Surgery.

Throughout its evolution, spine surgery has migrated toward less invasiveness. For posterior lumbar surgery, percutaneous techniques together with endoscopic visualization allow for the smallest surgical corridor. Initially, this approach utilized the natural entry point into the spinal canal via the transforaminal approach via Kamin's triangle. The interlaminar endoscopic technique was subsequently developed to address central disc herniations at L5-S1, where the transforaminal approach can be challenging to reach the surgical pathology. More recently, the dual portal posterior lumbar endoscopic technique provides for yet another method of performing posterior lumbar surgery, expanding its versatility, including the treatment of spinal stenosis. In addition to treating disc pathology, percutaneous endoscopic lumbar interbody fusions are now performed in select patients in the ambulatory surgery setting. Despite the dramatic advantages of advanced minimally invasive procedures, the adoption of endoscopic spine surgery in everyday practice has lagged. The main obstacle to adoption appears to be the difficult learning curve of endoscopic surgery combined with the fact that traditional microdiscectomy surgery remains one of the most successful operations in our treatment armamentarium. The successful future of endoscopic spine surgery will depend on our ability to address the learning curve problem. In the future, this problem may be addressed through the use to computer-assisted navigation, robotic assistance, and an integrated operating room suite that improves the efficiencies and ergonomics of increasingly complex surgical treatment strategies.

International Society for the Advancement of Spine Surgery Policy 2019-Surgical Treatment of Lumbar Disc Herniation with Radiculopathy.

Lumbar disc herniation (LDH) is a frequent cause of low back pain and radiculopathy, disability, and diminution in quality of life. While nonsurgical care remains the mainstay of initial treatment, symptoms that persist for prolonged periods of time are well treated with discectomy surgery. A large body of evidence shows that, in patients with unremitting symptoms despite a reasonable period of nonsurgical treatment, discectomy surgery is safe and efficacious. In patients with symptoms lasting greater than 6 weeks, various forms of discectomy (open, microtubular, and endoscopic) are superior to continued nonsurgical treatment. The small but significant proportion of patients with recurrent disc herniation experience less improvement overall than patients who do not experience reherniation after primary discectomy. Lumbar discectomy patients with large annular defects (≥6 mm wide) are at a higher risk for recurrent herniation and revision surgery. Annular closure via a bone-anchored device has been shown to decrease the rate of recurrent disc herniation and associated reoperation in these high-risk patients. After a detailed review of the literature, current clinical evidence supports discectomy (open, microtubular, or endoscopic discectomy) as a medically necessary procedure for the treatment of LDH with radiculopathy in indicated patients. Furthermore, there is new scientific evidence that supports the use of bone-anchored annular closure in patients with large annular defects, who are at greater risk for recurrent disc herniation.

Two-Year Clinical and Radiographic Outcomes of Expandable Interbody Spacers Following Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Prospective Study.

BACKGROUND: The advantages of minimally invasive surgery for transforaminal lumbar interbody fusion (MIS TLIF) are well documented and include decreased blood loss, shorter length of hospital stay, and reduced perioperative costs. Clinical evidence for the use of expandable interbody spacers in conjunction with MIS TLIF, however, is scarce. This study sought to examine the clinical and radiographic outcomes of patients undergoing MIS TLIF with an expandable spacer. METHODS: Forty patients from 4 institutions who underwent MIS TLIF with an expandable spacer were included in this study and followed for 24 months. Investigator assessment of the surgical technique was reported. Patient self-reported outcomes included Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Short Form 36 (SF-36) physical and mental component scores. Disc height, foraminal height, segmental and lumbar lordosis, and fusion were also assessed. RESULTS: Investigators reported that intraoperative insertion, impaction, number of passes through the neural structures, and fit were better with an expandable spacer than a static spacer. Significant improvements in VAS, ODI, and SF-36 were reported as early as 6 weeks postoperatively and maintained through 24 months. Mean intervertebral and foraminal heights improved significantly from the preoperative time interval to as early as 6 weeks postoperatively and maintained through 24 months. There were no cases of spacer migration, subsidence, or collapse. CONCLUSIONS: The use of an expandable interbody spacer in combination with MIS TLIF resulted in positive investigator assessments, immediate and progressive symptom relief, significant radiographic improvements, and no spacer-related complications.

Use of navigation-assisted fluoroscopy to decrease radiation exposure during minimally invasive spine surgery.

BACKGROUND: Minimally invasive surgery decreases postoperative pain and disability. However, limited views of the surgical field require extensive use of intraoperative fluoroscopy that may expose the surgical team to higher levels of ionizing radiation. PURPOSE: To assess the feasibility and safety of navigation-assisted fluoroscopy during minimally invasive spine surgery. STUDY DESIGN: A combined cadaveric and human study comparing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) using navigation-assisted fluoroscopy with standard intraoperative fluoroscopy to determine differences in surgical times and radiation exposures. METHODS: Eighteen fresh cadaveric spines underwent unilateral MIS TLIF by using either navigation-assisted fluoroscopy or standard fluoroscopy. Times for specific surgical steps were compared. In addition, a prospective short-term evaluation of the intraoperative and perioperative results of 10 patients undergoing navigation-assisted MIS TLIF (NAV group) compared with a retrospective review of 8 patients undergoing MIS TLIF performed by using standard fluoroscopy (FLUORO group). RESULTS: In the cadaveric study, the times were similar between the NAV group and the FLUORO group for most key steps. No statistically significant differences were obtained for approach, exposure, screw insertion, facetectomy/decompression, or total surgical times. Statistically significant differences were obtained for the setup time and total fluoroscopy time. The setup time for the NAV group averaged 9.67 (standard deviation [SD], 3.74) minutes compared with 4.78 (SD, 2.11) minutes for the FLUORO group (p=.034). The total fluoroscopy time was higher for the FLUORO group compared with the NAV group (41.9 seconds vs. 28.7 seconds, p=.042). Radiation exposure was undetectable when navigation-assisted fluoroscopy is used (NAV group). In contrast, an average 12.4 milli-REM (mREM) of radiation exposure is delivered to the surgeon during unilateral MIS TLIF procedure without navigation (FLUORO group). In the clinical series, the total fluoro time for the NAV group was 57.1 seconds (SD, 37.3; range, 18-120) compared with 147.2 seconds (SD, 73.3; range, 73-295) for FLUORO group (p=.02). No statistically significant differences are noted for operating time, estimated blood loss, or hospital stay. No inadvertent durotomies, postoperative weakness, or new radiculopathy were noted in the NAV group. One inadvertent durotomy was encountered in the FLUORO group that was repaired intraoperatively without clinical sequelae. CONCLUSION: The use of navigation-assisted fluoroscopy is feasible and safe for minimally invasive spine surgery. Radiation exposure is decreased to the patient as well as the surgical team.

Altered bioreactivity and limited osteoconductivity of calcium sulfate-based bone cements in the osteoporotic rat spine.

BACKGROUND CONTEXT: Previous studies documenting the osteoconductive nature of calcium sulfate (CaSO(4))-based biomaterials have been largely limited to animal models exhibiting nonosteoporotic bone biology. In addition to diminished bone mineral density (BMD) and altered bone microarchitecture, the osteoporosis phenotype is associated with a proinflammatory and pro-osteolytic state. Thus, osteoporosis may elicit an amplified bioreactivity to common orthopedic biomaterials, potentially limiting their full osteoconductive capabilities in vivo. PURPOSE: The purpose of this study is to test the hypothesis that CaSO(4)-based bone cements exhibit altered bioreactivity and limited osteoconductivity in response to osteoporotic conditions. STUDY DESIGN: 1) Microcomputed tomography (micro-CT) radiomorphometry study and 2) histological analysis. METHODS: Our laboratory has previously established a preclinical model of osteoporosis using the rodent osteoporotic spine (OS). Caudal vertebral defects were filled with either CaSO(4) or CaSO(4)/CaPO(4) (Hybrid) cement for each group (n=4). Over 8 weeks, cement resorption profiles, BMD, average cortical thickness, average trabecular thickness, average trabecular spacing, and diaphyseal bone volume fraction were assessed via micro-CT radiomorphometry. Histological analysis was performed on vertebrae obtained postsurgery and at Week 8. RESULTS: Both materials displayed an accelerated cement resorption profile after implantation into the OS vertebrae. Hybrid cement exhibited slower resorption compared with that of CaSO(4) under both normal female rats (NL) and OS conditions. The cement-mediated bone augmentation observed in the NL spine was altered under OS conditions. CONCLUSIONS: This study suggests that cement bioreactivity is heightened and osteoconductivity may be limited in a preclinical model of the OS. The disparity between the two resorption profiles suggests that this accelerated cement resorption is a material-dependent phenomenon. The proinflammatory and pro-osteolytic bone environment associated with the osteoporosis disease state may contribute to the accelerated resorption and altered osteoconductivity exhibited by both materials. Future study of potential biomaterials intended for use within the OS may necessitate further exploration of the relationship between biomaterial performance and osteoporosis bone biology.

Intra- and Perioperative Complications Associated with Endoscopic Spine Surgery: A Multi-Institutional Study.

OBJECTIVE: To report on intra- and perioperative complications associated with working channel endoscopic spine surgery. METHODS: This study is a retrospective chart review of a multi-institutional patient cohort operated on by surgeons within the Endoscopic Spine Study Group between May 2010 and June 2017. RESULTS: Our study cohort consists of a total of 553 consecutive cases with an average age of 57 years. The most common procedure was an endoscopic discectomy (n = 377, 68%) followed by foraminotomy (n = 156, 28.2%), unilateral laminotomy for bilateral decompression (n = 55, 9.9%), and lateral recess decompression (n = 29, 5.2%). Overall, the rate of intra- and perioperative complications was 2.7%. There were 3 durotomies (0.54%), 2 epidural hematomas (0.36%), 2 patients developed a complex pain disorder (0.36%), 4 recurrent disc herniations within 3 months (1.1%), 4 systemic complications (1.1%), and no wound infections. No risk factors were identified with regards to age, sex, approach, or number of segments. CONCLUSIONS: Endoscopic spine surgery is associated with a favorable rate of intra- and perioperative complications compared with reported rates of minimally invasive ortraditional open spine surgeries. Our report proposes safe and effective strategies for management of these complications.

Conversion of bulk seashells to biocompatible hydroxyapatite for bone implants.

Strombus gigas (conch) shells and Tridacna gigas (Giant clam) shells have dense, tailored structures that impart excellent mechanical properties to these shells. In this investigation, conch and clam seashells were converted to hydroxyapatite (HAP) by a hydrothermal method at different temperatures and for different conversion durations. Dense HAP structures were created from these shells throughout the majority of the samples at the relative low temperature of approximately 200 degrees C. The average fracture stress was found to be approximately 137-218MPa for partially converted conch shell samples and approximately 70-150MPa for original and converted clamshell samples, which is close to the mechanical strength of compact human bone. This indicates that the converted shell samples can be used as implants in load-bearing cases. In vivo tests of converted shell samples were performed in rat femoral defects for 6 weeks. The microtomography images at 6 weeks show that the implants did not move, and untreated control defects remain empty with no evidence of a spontaneous fusion. Histological study reveals that there is newly formed bone growing up to and around the implants. There is no evidence of a fibrosis tissue ring around the implants, also indicating that there is no loosening of the implants. In contrast, the untreated controls remain empty with some evidence of a fibrosis ring around the defect hole. These results indicate good biocompatibility and bioactivity of the converted shell implants.

Conversion of sea urchin spines to Mg-substituted tricalcium phosphate for bone implants.

The skeleton of sea urchin spines is composed of large single crystals of Mg-rich calcite, which have smooth, continuously curved surfaces and form a three-dimensional fenestrated mineral network. Spines of the echinoids Heterocentrotus trigonarius and Heterocentrotus mammillatus were converted by the hydrothermal reaction at 180 degrees C to bioresorbable Mg-substituted tricalcium phosphate (beta-TCMP). Due to the presence of Mg in the calcite lattice, conversion to beta-TCMP occurs preferentially to hydroxyapatite formation. The converted beta-TCMP still maintains the three-dimensional interconnected porous structures of the original spine. The main conversion mechanism is the ion-exchange reaction, although there is also a dissolution-reprecipitation process that forms some calcium phosphate precipitates on the surfaces of the spine network. The average fracture strength of urchin spines and converted spines (beta-TCMP) in the compression tests are 42 and 23MPa, respectively. In vivo studies using a rat model demonstrated new bone growth up to and around the beta-TCMP implants after implantation in rat femoral defects for 6 weeks. Some new bone was found to migrate through the spine structural pores, starting from the outside of the implant through the pores at the edge of the implants. These results indicate good bioactivity and osteoconductivity of the porous beta-TCMP implants.

A rat osteoporotic spine model for the evaluation of bioresorbable bone cements.

BACKGROUND CONTEXT: As the aging population increases, the rising prevalence of osteoporosis-related spine fractures will have a dramatic impact on health care. At present, mainstay treatment relies on systemic medications intended to prevent diminishing bone mineral density (BMD) and bone mass. However, an adjunctive treatment strategy is to target specific areas of the skeletal system that are prone to clinically significant osteoporotic fractures. We term this strategy the "local treatment of osteoporosis" or osteoplasty. Potential use of osteoplasty involves the percutaneous injection of bioresorbable and bioactive bone cements into bones at risk of sustaining osteoporotic fractures. Calcium sulfate (CaSO(4)) is among the candidate bioresorbable bone cements with the material attributes desirable for potential application with osteoplasty, yet previous studies on the osteoconductive properties of CaSO(4) have been limited to animal models exhibiting normal bone biology and architecture. However, osteoporotic bone physiology may potentially interfere with the material properties of common osteoconductive biomaterials, such as that of CaSO(4). To further test this hypothesis, a suitable animal model is needed to evaluate the in vivo behavior of potential biomaterials in osteoporotic bone. PURPOSE: The purpose of this study is to evaluate the caudal (proximal tail) rat vertebral body as an appropriate system for the in vivo evaluation of bone cement performance in the osteoporotic spine. STUDY DESIGN: (1) Micro-computed tomography radiomorphometry study and (2) biomechanical vertebral compression analysis. METHODS: Female Sprague Dawley rats were ovarectomized (OVX) at age 8 weeks and subsequently maintained on a low-calcium diet for 3 months. Normal nonovarectomized female rats (NL) of similar age and size were maintained on regular rodent feed. Micro-CT analysis was performed on both the lumbar and caudal vertebrae (levels 5-7) of both groups. The following bone radiomorphometric parameters were determined: bone mineral density (BMD), average cortical thickness (ACT), average trabecular thickness (TbTh), and average trabecular spacing (TbSp). Strength and stiffness of both NL and OVX vertebral bodies were assessed under axial compression at 0.1 mm/s, whereas displacement (mm) and force (N) were measured at 10 Hz until completion to failure. After the implantation of an injectable form of CaSO(4) bone cement into caudal vertebrae, radiomorphometric analysis of cement volume, based on its unique CT absorption profile, was performed over the 8-week time period, as well as the subsequent bone response of both NL and OVX caudal vertebrae to CaSO4. RESULTS: OVX caudal vertebrae showed an 18% decrease in BMD, a 28% decrease in diaphyseal ACT, a 55% decrease in TbTh, and a 2.4-fold increase in TbSp compared with NL (p<.05). Additionally, lumbar vertebrae exhibited a 21% decrease in BMD, a 24% decrease in anterior body ACT, a 48% decrease in TbTh, and a 4.7-fold increase in TbSp (p<.05). Failure testing of OVX caudal vertebral bodies revealed a 29% decrease in strength and a 60% decrease in stiffness compared with NL (p<.01). After implantation into OVX caudal vertebrae, CaSO(4) cement exhibited a 50% decrease in initial cement volume at 2 weeks and complete resorption by 4 weeks, whereas CaSO(4) injected into NL vertebrae exhibited a 79% decrease in initial cement volume at 4 weeks, trace amounts at 6 weeks, and complete resorption by 8 weeks. At 8 weeks, NL vertebrae implanted with CaSO(4) cement exhibited increased cortical bone thickness compared with NL sham vertebrae. This CaSO(4) cement-mediated bone augmentation was altered in osteoporotic vertebrae that exhibited porous irregular cortical bone not noted in cement-treated NL vertebrae or OVX sham vertebrae. CONCLUSIONS: Future investigation of potential biomaterials intended for the local treatment of osteoporosis will require their study within an appropriate osteoporosis animal model. The OVX rat caudal spine exhibits pathologic bone changes consistent with the osteoporosis phenotype, including decreased BMD, diminished trabecular network density, cortical thinning, and decreased mechanical strength. These derangements in bone microarchitecture and physiology may contribute toward the accelerated cement resorption and altered bone response to CaSO4 observed in this study. Important advantages of the OVX rat caudal spine are the rapid and minimally invasive surgical exposure of the vertebral body and the ease of cement injection. We propose that the OVX rat caudal spine represents a valuable and cost-effective tool in the armamentarium of investigators evaluating biomaterials designed for implantation into the osteoporotic spine.

The effect of anterior longitudinal ligament resection on lordosis correction during minimally invasive lateral lumbar interbody fusion: Biomechanical and radiographic feasibility of an integrated spacer/plate interbody reconstruction device.

BACKGROUND: Lateral lumbar interbody fusion is powerful for correcting degenerative conditions, yet sagittal correction remains limited by anterior longitudinal ligament tethering. Although lordosis has been restored via ligament release, biomechanical consequences remain unknown. Investigators examined radiographic and biomechanical of ligament release for restoration of lumbar lordosis. METHODS: Six fresh-frozen human cadaveric spines (L3-S1) were tested: (Miller et al., 1988) intact; (Battie et al., 1995) 8mm spacer with intact anterior longitudinal ligament; (Cho et al., 2013) 8mm spacer without intact ligament following ligament resection; (Galbusera et al., 2013) 13mm lateral lumbar interbody fusion; (Goldstein et al., 2001) integrated 13mm spacer. Focal lordosis and range of motion were assessed by applying pure moments in flexion-extension, lateral bending, and axial rotation. FINDINGS: Cadaveric radiographs showed significant improvement in lordosis correction following ligament resection (P<0.05). The 8mm spacer with ligament construct provided greatest stability relative to intact (P>0.05) but did little to restore lordosis. Ligament release significantly destabilized the spine relative to intact in all modes and 8mm with ligament in lateral bending and axial rotation (P<0.05). Integrated lateral lumbar interbody fusion following ligament resection did not significantly differ from intact or from 8mm with ligament in all testing modes (P>0.05). INTERPRETATION: Lordosis corrected by lateral lumbar interbody fusion can be improved by anterior longitudinal ligament resection, but significant construct instability and potential implant migration/dislodgment may result. This study shows that an added integrated lateral fixation system can significantly improve construct stability. Long-term multicenter studies are needed.

Validity and reliability of a novel patient reported outcome tool to evaluate post-operative dysphagia, odynophagia, and voice (DOV) disability after anterior cervical procedures.

BACKGROUND: Existing evaluative instruments for dysphagia, odynophagia, and voice disturbance are cumbersome, focus pre-dominately on dysphagia, and often require administration by a certified Speech Pathologist. This study was conducted to utilize widely accepted instruments such as the American Speech and Hearing Association's National Outcomes Measurement System (NOMS) and VAS pain scales to validate a novel, patient-reported instrument that quantifies the severity of post-operative dysphagia, odynophagia, and voice disabilities (DOV). METHODS: The DOV was developed and subjected to multiple rounds of face and content validation by representative patient cohorts and a panel of clinical experts. An established, prospective clinical registry was utilized to collect pre and post-operative VAS-swallow related pain and DOV measurements for subjects with recent anterior cervical procedures (n=25 content validation, n=20 criterion validation), or recent lumbar decompressions (n=33). NOMS evaluations were performed by a certified Speech Language Pathologist on the first post-operative day after minimally invasive anterior approaches to cervical reconstruction were performed in the criterion validation cohort. RESULTS: Content validity: Subjects with a recent anterior cervical procedure reported a significant increase in post-operative dysphagia (pre-op: 0.13±0.35, post-op: 1.08±1.41, p=0.01), odynophagia (pre-op: 0.24±0.69, post-op: 0.84±0.90, p=0.001), and voice (pre-op: 0.10±0.41, post-op: 0.88±0.92, p=0.0004) disturbance. In contrast, subjects with a recent lumbar procedure did not demonstrate a significant increase in post-operative dysphagia, odynophagia, or voice disturbance (p>0.05).Criterion validity: Chi-squared contingency testing for independence between converted NOMS and DOV instrument scores accepted linkage between the two instruments for dysphagia X2(DF: 12, n=20, Expected: 21.03, Observed: 24.4, p: 0.02) and voice X2(DF: 6, n=20, Expected: 12.60, Observed: 21.28, p: 0.002) dimensions. Similarly, converted swallow related VAS and DOV odynophagia instruments demonstrated linkage X2(DF: 9, n=20, Expected: 16.92, Observed: 24.21, p: 0.004).Internal Reliability: Chronbach's alpha coefficient of reliability was 0.74 between all DOV survey dimensions. CONCLUSIONS: The DOV survey is a valid patient-reported instrument to rapidly and reliably detect post-operative swallow and voice dysfunction.

A Novel Collaborative Protocol for Successful Management of Penile Pain Mediated by Radiculitis of Sacral Spinal Nerve Roots From Tarlov Cysts.

INTRODUCTION: Since 14 years of age, the patient had experienced extreme penile pain within seconds of initial sexual arousal through masturbation. Penile pain was so severe that he rarely proceeded to orgasm or ejaculation. After 7 years of undergoing multiple unsuccessful treatments, he was concerned for his long-term mental health and for his future ability to have relationships. AIM: To describe a novel collaboration among specialists in sexual medicine, neurophysiology, and spine surgery that led to successful management. METHODS: Collaborating health care providers conferred with the referring physician, patient, and parents and included a review of all medical records. MAIN OUTCOME MEASURE: Elimination of postpubertal intense penile pain during sexual arousal. RESULTS: The patient presented to our sexual medicine facility at 21 years of age. The sexual medicine physician identifying the sexual health complaint noted a pelvic magnetic resonance imaging report of an incidental sacral Tarlov cyst. A subsequent sacral magnetic resonance image showed four sacral Tarlov cysts, with the largest measuring 18 mm. Neuro-genital testing result were abnormal. The neurophysiologist hypothesized the patient's pain at erection was produced by Tarlov cyst-induced neuropathic irritation of sensory fibers that course within the pelvic nerve. The spine surgeon directed a diagnostic injection of bupivacaine to the sacral nerve roots and subsequently morphine to the conus medullaris of the spinal cord. The bupivacaine produced general penile numbness; the morphine selectively decreased penile pain symptoms during sexual arousal without blocking penile skin sensation. The collaboration among specialties led to the conclusion that the Tarlov cysts were pathophysiologically mediating the penile pain symptoms during arousal. Long-term follow-up after surgical repair showed complete symptom elimination at 18 months after treatment. CONCLUSION: This case provides evidence that (i) Tarlov cysts can cause sacral spinal nerve root radiculitis through sensory pelvic nerve and (ii) there are management benefits from collaboration among sexual medicine, neurophysiology, and spine surgery subspecialties. Goldstein I, Komisaruk BR, Rubin RS, et al. A Novel Collaborative Protocol for Successful Management of Penile Pain Mediated by Radiculitis of Sacral Spinal Nerve Roots From Tarlov Cysts. Sex Med 2017;5:e203-e211.