The influence of backbone fluorination on the helicity of α/γ-hybrid peptides.

Peptides that are composed of an alternating pattern of α- and γ-amino acids are potentially valuable as metabolism-resistant bioactive agents. For optimal function, some kind of conformational restriction is usually required to either stabilize the dominant 12-helix, or else to divert the peptide away from this conformation in a controlled way. Herein, we explore stereoselective fluorination as a method for controlling the conformations of α/γ-hybrid peptides. We show through a combination of X-ray, NMR and CD analyses that fluorination can either stabilize or disrupt the 12-helix, depending on the fluorine stereochemistry. These findings could inform the ongoing development of diverse functional hybrid peptides.

In-silico analysis of probiotic attributes and safety assessment of probiotic strain Bacillus coagulans BCP92 for human application.

The whole genome sequence (WGS) of Bacillus coagulans BCP92 is reported along with its genomic analysis of probiotics and safety features. The identification of bacterial strain was carried out using the 16S rDNA sequencing method. Furthermore, gene-related probiotic features, safety assessment (by in vitro and in silico), and genome stability were also studied using the WGS analysis for the possible use of the bacterial strain as a probiotic. From the BLAST analysis, bacterial strain was identified as Bacillus (Heyndrickxia) coagulans. WGS analysis indicated that the genome consists of a 3 475 658 bp and a GC-content of 46.35%. Genome mining of BCP92 revealed that the strain is consist of coding sequences for d-lactate dehydrogenase and l-lactate dehydrogenases, 36 genes involved in fermentation activities, 29 stress-responsive as well as many adhesions related genes. The genome, also possessing genes, is encoded for the synthesis of novel circular bacteriocin. Using an in-silico approach for the bacterial genome study, it was possible to determine that the Bacillus (Heyndrickxia) coagulans strain BCP92 contains genes that are encoded for the probiotic abilities and did not harbour genes that are risk associated, thus confirming the strain's safety and suitability as a probiotic to be used for human application.

Meta-analysis of endometrial transcriptome data reveals novel molecular targets for recurrent implantation failure.

PURPOSE: Gene expression analysis of the endometrium has been shown to be a useful approach for identifying the molecular signatures and pathways involved in recurrent implantation failure (RIF). Nevertheless, individual studies have limitations in terms of study design, methodology and analysis to detect minor changes in expression levels or identify novel gene signatures associated with RIF. METHOD: To overcome this, we conducted an in silico meta-analysis of nine studies, the systematic collection and integration of gene expression data, utilizing rigorous selection criteria and statistical techniques to ensure the robustness of our findings. RESULTS: Our meta-analysis successfully unveiled a meta-signature of 49 genes closely associated with RIF. Of these genes, 38 were upregulated and 11 downregulated in RIF patients' endometrium and believed to participate in key processes like cell differentiation, communication, and adhesion. GADD45A, IGF2, and LIF, known for their roles in implantation, were identified, along with lesser-studied genes like OPRK1, PSIP1, SMCHD1, and SOD2 related to female infertility. Many of these genes are involved in MAPK and PI3K-Akt pathways, indicating their role in inflammation. We also investigated to look for key miRNAs regulating these 49 dysregulated mRNAs as potential diagnostic biomarkers. Along with this, we went to associate protein-protein interactions of 49 genes, and we could recognize one cluster consisting of 11 genes (consisted of 22 nodes and 11 edges) with the highest score (p = 0.001). Finally, we validated some of the genes by qRT-PCR in our samples. CONCLUSION: In summary, the meta-signature genes hold promise for improving RIF patient identification and facilitating the development of personalized treatment strategies, illuminating the multifaceted nature of this complex condition.

Quantifying Patient Expectations for Total Knee Arthroplasty: Expectations for Improvement Are Greater Than Minimal Clinically Important Difference.

BACKGROUND: Achieving a minimal clinically important difference (MCID) in patient-reported outcomes following total knee arthroplasty (TKA) is common, yet up to 20% patient dissatisfaction persists. Unmet expectations may explain post-TKA dissatisfaction. No prior studies have quantified patient expectations using the same patient-reported outcome metric as used for MCID to allow direct comparison. METHODS: This was a prospective study of patients undergoing TKA with 5 fellowship-trained arthroplasty surgeons at one academic center. Baseline Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain Interference (PI) domains were assessed. Expected PROMIS scores were determined by asking patients to indicate the outcomes they were expecting at 12 months postoperatively. Predicted scores were generated from a predictive model validated in the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) dataset. T-tests were used to compare baseline, expected, and predicted PROMIS scores. Expected scores were compared to PROMIS MCID values obtained from the literature. Regression models were used to identify patient characteristics associated with high expectations. RESULTS: There were 93 patients included. Mean age was 67 years (range, 30 to 85) and 55% were women. Mean baseline PROMIS PF and PI was 34.4 ± 6.7 and 62.2 ± 6.4, respectively. Patients expected significant improvement for PF of 1.9 times the MCID (MCID = 11.3; mean expected improvement = 21.6, 95% confidence interval [CI] 19.6 to 23.5, P < .001) and for PI of 2.3 times the MCID (MCID = 8.9; mean expected improvement = 20.6, 95% CI 19.1-22.2, P < .001). Predicted scores were significantly lower than expected scores (mean difference = 9.5, 95% CI 7.7 to 11.3, P < .001). No unique patient characteristics were associated with high expectations (P > .05). CONCLUSIONS: To our knowledge, this study is the first to quantify preoperative patient expectations using the same metric as MCID to allow for direct comparison. Patient expectations for improvement following TKA are ∼2× greater than MCID and are significantly greater than predicted outcome scores. This discrepancy challenges currently accepted standards of success after TKA and indicates a need for improved expectation setting prior to surgery.

Laparoscopic guided liposomal bupivacaine injection compared to transversus abdominus plane block for postoperative pain after robotic gynecologic oncology surgery.

OBJECTIVE: The purpose of this study was to determine if laparoscopically guided transversus abdominis plane block (Lap-Tap) with liposomal bupivacaine provides superior postoperative pain control when compared to ultrasound-guided block (US-Tap) with liposomal bupivacaine at the time of robotic surgery for gynecology oncology patients. METHODS: This was a prospective randomized controlled trial assigning patients to one of two cohorts: Cohort 1 consisted of US-Tap administered before the procedure using liposomal bupivacaine, Cohort 2 consisted of Lap-Tap administration with laparoscopic visualization using the medication above. Primary outcomes were pain scores and total opioid use in Oral Morphine Equivalents (OME) during the first 72 h after surgery. Secondary outcomes were postoperative pain satisfaction and oral narcotic requirements. RESULTS: There was a significant increase in oral narcotic use in the first 24 h in the US-Tap cohort compared to the Lap-Tap cohort: Lap-Tap mean = 6.73 ± 8.22 OME versus US-Tap mean = 12.69 ± 12.94 p = 0.018 OME. The increase was equivalent to one additional Hydrocodone-Acetaminophen 7.5 mg/325 mg in the first 24 h after surgery. However, total oral narcotic use over the first 72 h was not significantly different between the two cohorts: Lap-Tap mean = 21.73 ± 19.83 OME, US-Tap mean = 32.50 ± 29.47, p = 0.062 OME. In addition, there was no significant difference in satisfaction or pain scores between the US-Tap and Lap-Tap groups at 24, 48, or 72-hours. CONCLUSIONS: Lap-Taps are comparable to US-Tap for postoperative analgesia during the first 72-h after surgery when performing robotic-assisted gynecologic oncology surgery.

An international survey of the structure and process of care for traumatic spinal cord injury in acute and rehabilitation facilities: lessons learned from a pilot study.

BACKGROUND: To describe the key findings and lessons learned from an international pilot study that surveyed spinal cord injury programs in acute and rehabilitation facilities to understand the status of spinal cord injury care. METHODS: An online survey with two questionnaires, a 74-item for acute care and a 51-item for rehabilitation, was used. A subset of survey items relevant to the themes of specialized care, timeliness, patient-centeredness, and evidence-based care were operationalized as structure or process indicators. Percentages of facilities reporting the structure or process to be present, and percentages of indicators met by each facility were calculated and reported separately for facilities from high-income countries (HIC) and from low and middle-income countries (LMIC) to identify "hard to meet" indicators defined as those met by less than two-thirds of facilities and to describe performance level. RESULTS: A total of 26 acute and 26 rehabilitation facilities from 25 countries participated in the study. The comparison of the facilities based on the country income level revealed three general observations: 1) some indicators were met equally well by both HIC and LMIC, such as 24-hour access to CT scanners in acute care and out-patient services at rehabilitation facilities; 2) some indicators were hard to meet for LMIC but not for HIC, such as having a multidisciplinary team for both acute and rehabilitation settings; and 3) some indicators were hard to meet by both HIC and LMIC, including having peer counselling programs. Variability was also observed for the same indicator between acute and rehabilitation facilities, and a wide range in the total number of indicators met among HIC facilities (acute 59-100%; rehabilitation 36-100%) and among LMIC facilities (acute: 41-82%; rehabilitation: 36-93%) was reported. CONCLUSIONS: Results from this international pilot study found that the participating acute and rehabilitation facilities on average adhered to 74% of the selected indicators, suggesting that the structure and processes to provide ideal traumatic spinal cord injury care were broadly available. Recruiting a representative sample of SCI facilities and incorporating regional attributes in future surveys will be helpful to examine factors affecting adherence to indicators.

Ameliorative effects of curcumin against lead induced toxicity in human peripheral blood lymphocytes culture.

Lead, a heavy metal and multifaceted toxicant, is well studied for its distribution and toxicity in ecosystem, yet there is no consensus on its amelioration by any synthetic or phytochemical compounds. Curcumin, a known antioxidant and dietary element, is a well-known herb, for its therapeutic uses and having a wide spectrum of its beneficial properties against several adverse effects. Hence, the current study was taken into consideration to evaluate the ameliorative effects of curcumin (3.87 µM, i.e. 1.43 µg/ml) against lead acetate (doses: 10-6 M, i.e. 0.379 µg/ml and 10-4 M, i.e. 37.9 µg/ml, durations: 24 h and 69 h) induced genotoxicity and oxidative stress in human peripheral blood lymphocyte cultures (PBLC). On one hand, antigenotoxic and antioxidative potentials of curcumin against lead were simultaneously evaluated by the array of genotoxicity and oxidative stress indices. The result postulated that lead acetate showed dose- and duration-dependent increase in both genotoxicity and oxidative stress whereas curcumin, when added along with lead acetate, showed the significant amelioration in all genotoxic and oxidative stress-related indices. The study indicated that, due to alteration in antioxidant defense system, there is an adverse genotoxic effect of lead. On the other hand, curcumin, a potent antidote, can protect chromatin material against lead -mediated genotoxicity by balancing the activity of antioxidant defense system.

An elastic second skin.

We report the synthesis and application of an elastic, wearable crosslinked polymer layer (XPL) that mimics the properties of normal, youthful skin. XPL is made of a tunable polysiloxane-based material that can be engineered with specific elasticity, contractility, adhesion, tensile strength and occlusivity. XPL can be topically applied, rapidly curing at the skin interface without the need for heat- or light-mediated activation. In a pilot human study, we examined the performance of a prototype XPL that has a tensile modulus matching normal skin responses at low strain (<40%), and that withstands elongations exceeding 250%, elastically recoiling with minimal strain-energy loss on repeated deformation. The application of XPL to the herniated lower eyelid fat pads of 12 subjects resulted in an average 2-grade decrease in herniation appearance in a 5-point severity scale. The XPL platform may offer advanced solutions to compromised skin barrier function, pharmaceutical delivery and wound dressings.

Divergent response of homologous ATP sites to stereospecific ligand fluorination for selectivity enhancement.

Acquiring a divergent response from homologous protein domains is essential for selective ligand-protein interactions. Stereospecific fluorination of (-)-balanol, an ATP mimic, uncovers a new source of selectivity from integrated chemical and conformational perturbation that differentiates homologous sites by the level of congruency in their response to local and remote fluorine effects.

Simultaneous DNA amplification and detection using a pH-sensing semiconductor system.

We developed an integrated chip for real-time amplification and detection of nucleic acid using pH-sensing complementary metal-oxide semiconductor (CMOS) technology. Here we show an amplification-coupled detection method for directly measuring released hydrogen ions during nucleotide incorporation rather than relying on indirect measurements such as fluorescent dyes. This is a label-free, non-optical, real-time method for detecting and quantifying target sequences by monitoring pH signatures of native amplification chemistries. The chip has ion-sensitive field effect transistor (ISFET) sensors, temperature sensors, resistive heating, signal processing and control circuitry all integrated to create a full system-on-chip platform. We evaluated the platform using two amplification strategies: PCR and isothermal amplification. Using this platform, we genotyped and discriminated unique single-nucleotide polymorphism (SNP) variants of the cytochrome P450 family from crude human saliva. We anticipate this semiconductor technology will enable the creation of devices for cost-effective, portable and scalable real-time nucleic acid analysis.

The role of intense athletic activity on structural lumbar abnormalities in adolescent patients with symptomatic low back pain.

PURPOSE: To determine if adolescent athletics increases the risk of structural abnormalities in the lumbar spine. METHODS: A retrospective review of patients (ages 10-18) between 2004 and 2012 was performed. Pediatric patients with symptomatic low back pain, a lumbar spine MRI, and reported weekly athletic activity were included. Patients were stratified to an "athlete" and "non-athlete" group. Lumbar magnetic resonance and plain radiographic imaging was randomized, blinded, and evaluated by two authors for a Pfirrmann grade, herniated disc, and/or pars fracture. RESULTS: A total of 114 patients met the inclusion criteria and were stratified into 66 athletes and 48 non-athletes. Athletes were more likely to have abnormal findings compared to non-athletes (67 vs. 40 %, respectively, p = 0.01). Specifically, the prevalence of a spondylolysis with or without a slip was higher in athletes vs. non-athletes (32 vs. 2 %, respectively, p = 0.0003); however, there was no difference in the average Pfirrmann grade (1.19 vs. 1.14, p = 0.41), percentage of patients with at least one degenerative disc (39 vs. 31 %, p = 0.41), or disc herniation (27 vs. 33 %, p = 0.43). Body mass index, smoking history, and pelvic incidence (51.5° vs. 48.7°, respectively, p = 0.41) were similar between the groups. CONCLUSION: Adolescents with low back pain have a higher-than-expected prevalence of structural pathology regardless of athletic activity. Independent of pelvic incidence, adolescent athletes with low back pain had a higher prevalence of spondylolysis compared to adolescent non-athletes with back pain, but there was no difference in associated disc degenerative changes or herniation.

What are the Risk Factors for Cerebrovascular Accidents After Elective Orthopaedic Surgery?

BACKGROUND: Perioperative cerebrovascular accidents (CVAs) are one of the leading causes of patient morbidity, mortality, and medical costs. However, little is known regarding the rates of these events and risk factors for CVA after elective orthopaedic surgery. QUESTIONS/PURPOSES: Our goals were to (1) establish the national, baseline proportion of patients experiencing a 30-day CVA and the timing of CVA; and (2) determine independent risk factors for 30-day CVA rates after common elective orthopaedic procedures. METHODS: Patients undergoing elective TKA, THA, posterior or posterolateral lumbar fusion, anterior cervical discectomy and fusion, and total shoulder arthroplasty, from 2006 to 2012, were identified from the American College of Surgeons National Surgical Quality Improvement Program(®) database. A total of 42,150 patients met inclusion criteria. Thirty-day CVA rates were recorded for each procedure, and patients were assessed for characteristics associated with CVA through univariate analysis. Multivariate regression models were created to identify independent risk factors for CVA. RESULTS: A total of 55 (0.13%) patients experienced a CVA within 30 days of the procedure, occurring a median of 2 days after surgery (range, 1-30 days) with 0.08% of patients experiencing a CVA after TKA, 0.15% after THA, 0.00% after single-level anterior cervical discectomy and fusion, 0.38% after multilevel anterior cervical discectomy and fusions, 0.20% after single-level posterior or posterolateral lumbar fusion, 0.70% after multilevel posterior or posterolateral lumbar fusion, and 0.22% after total shoulder arthroplasty. Independent risk factors for CVA included age of 75 years or older (odds ratio [OR], 2.50; 95% CI, 1.44-4.35; p = 0.001), insulin-dependent diabetes mellitus (OR, 3.08; CI, 1.47-6.45; p = 0.003), hypertension (OR, 2.71; CI, 1.19-6.13; p = 0.017), history of transient ischemic attack (OR, 2.83; CI, 1.24-6.45; p = 0.013), dyspnea (OR, 2.51; CI, 1.30-4.86; p = 0.006), chronic obstructive pulmonary disease (OR, 2.33; CI, 1.06-5.13; p = 0.036), and operative time of 180 minutes or greater (OR, 3.25; CI 1.60-6.60; p = 0.001). CONCLUSIONS: Numerous nonmodifiable patient comorbidities and increased operative time were associated with CVA after elective orthopaedic procedures. However, the American College of Surgeons National Surgical Quality Improvement Program(®) database does not code for cardiac arrhythmia or atrial fibrillation, which other studies have suggested may be important predictor variables; those may be important risk factors, although we were unable to evaluate them in our study. Surgeons should counsel patients with these risk factors and limit their operative time to reduce the risk of these adverse events, and future studies should examine other patient characteristics such as arrhythmia and noncoronary heart disease and assess the role of pharmacologic prophylaxis in patients with these risk factors. LEVEL OF EVIDENCE: Level III, prognostic study.

Cervical spine surgery in professional athletes: a systematic review.

Cervical surgery is one of the most common surgical spinal procedures performed around the world. The authors performed a systematic review of the literature reporting the outcomes of cervical spine surgery in high-level athletes in order to better understand the nuances of cervical spine pathology in this population. A search of the MEDLINE database using the search terms "cervical spine" AND "surgery" AND "athletes" yielded 54 abstracts. After exclusion of publications that did not meet the criteria for inclusion, a total of 8 papers reporting the outcome of cervical spine surgery in professional or elite athletes treated for symptoms secondary to cervical spine pathology (focusing in degenerative conditions) remained for analysis. Five of these involved the management of cervical disc herniation, 3 were specifically about traumatic neurapraxia. The majority of the patients included in this review were American football players. Anterior cervical discectomy and fusion (ACDF) was commonly performed in high-level athletes for the treatment of cervical disc herniation. Most of the studies suggested that return to play is safe for athletes who are asymptomatic after ACDF for cervical radiculopathy due to disc herniation. Surgical treatment may provide a higher rate of return to play for these athletes than nonsurgical treatment. Return to play after cervical spinal cord contusion may be possible in asymptomatic patients. Cervical cord signal changes on MRI may not be an absolute contraindication for return to play in neurologically intact patients, according to some authors. Cervical contusions secondary to cervical stenosis may be associated with a worse outcome and a higher recurrence rate than those those secondary to disc herniation. The evidence is low (Level IV) and individualized treatment must be recommended.

Simplifying optimal tooth-size calculations and communications between practitioners.

The purpose of this article is to present a simple method for determining the optimal sizes of anterior teeth. This is needed because of the frequency of anomalous and missing maxillary lateral incisors. In addition to anomalous and missing incisors, other factors that create challenges for the dentist and orthodontist when designing an esthetic and occlusally sound dentition are attrition, trauma, transposition, erosion, and caries. Optimal esthetics and occlusion require correctly sized teeth in proportion to themselves and the other teeth. Orthodontics, in partnership with restorative dentistry, allows doctors to accomplish the objectives of ideal occlusion and enhanced esthetics. Data compiled from previously published research enabled us to create simple formulae to determine optimal tooth sizes, an esthetic guide worksheet to use with collaborating dentists, and a sample written communication to accompany the completed esthetic guide worksheet. The method for establishing optimal tooth sizes is presented in a manner that allows easy memorization of the formulae and determination of the best dimensions for teeth without the use of a calculator.

Assessment of Various Nutritional Parameters in Geriatric Patients Who underwent Different Prosthodontic Treatments.

BACKGROUND: Some relation exists between oral and general health with progressive aging. Certain risk factors are common between oral and systemic diseases. Absence of teeth also affects the oral health by altering the quality of life. Hence, the nutritional changes occurring in elderly patients following prosthodontic rehabilitation are evaluated. MATERIALS AND METHODS: A total of 250 patients who underwent prosthodontic treatment for missing teeth were included for the study. Twice measurement of nutritional parameters was done: Initially at the time of diagnosis and then 5 months following commencement of the prosthodontic treatment. Dental analysis, evaluation of the diet, anthropometric assessment, and analysis of serum biochemical values were done in all the patients and tabulated records were maintained. Independent Student's t test and Tukey's test were done to assess the level of significance. RESULTS: A total of 250 patients were included for the study. The complete denture (CD) group showed the highest alteration in the mean values of the nutritional parameters followed by the removable partial denture group. A significant change was seen in the body mass index, protein, carbohydrate, and iron levels among the different patients who were grouped based on the mode of treatment modality. The CD group showed significantly higher mean change in carbohydrates value compared with mean change in patients receiving fixed treatment. CONCLUSION: Both nutrition and diet form an integral part of the prosthodontic treatment to maintain the health of elderly population. CLINICAL SIGNIFICANCE: With the advancement in the level of edentulism, rehabilitation by prosthetic treatment has become progressively important to restore and improve dietary parameters.

Surgical treatment of Type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumented fusion?

Odontoid fractures comprise as many as 20% of all cervical spine fractures. Fractures at the dens base, classified by the Anderson and D'Alonzo system as Type II injuries, are the most common pattern of all odontoid fractures and are also the most common cervical injuries in patients older than 70 years of age. Surgical treatment is recommended for patients older than 50 years with Type II odontoid fractures, as well as in patients at a high risk for nonunion. Anterior odontoid screw fixation (AOSF) and posterior cervical instrumented fusion (PCIF) are both well-accepted techniques for surgical treatment but with unique indications and contraindications as well as varied reported outcomes. In this paper, the authors review the literature about specific patients and fracture characteristics that may guide treatment toward one technique over the other. AOSF can preserve atlantoaxial motion, but requires a reduced odontoid, an intact transverse ligament, and a favorable fracture line to achieve adequate fracture compression. Additionally, older patients may have a higher rate of pseudarthrosis using this technique, as well as postoperative dysphagia. PCIF has a higher rate of fusion and is indicated in patients with severe atlantoaxial misalignment and with poor bone quality. PCIF allows direct open reduction of displaced fragments and can reduce any atlantoaxial subluxation. It is also used as a salvage procedure after failed AOSF. However, this technique results in loss of atlantoaxial motion, requires prone positioning, and demands a longer operative duration than AOSF, factors that can be a challenge in patients with severe medical conditions. Although both anterior and posterior approaches are acceptable, many clinical and radiological factors should be taken into account when choosing the best surgical approach. Surgeons must be prepared to perform both procedures to adequately treat these injuries.

Surgical Site Infections in Spinal Surgery.

Surgical site infections (SSIs) are a potentially devastating complication of spine surgery. SSIs are defined by the Centers for Disease Control and Prevention as occurring within 30 days of surgery or within 12 months of placement of foreign bodies, such as spinal instrumentation. SSIs are commonly categorized by the depth of surgical tissue involvement (ie, superficial, deep incisional, or organ and surrounding space). Postoperative infections result in increased costs and postoperative morbidity. Because continued research has improved the evaluation and management of spinal infections, spine surgeons must be aware of these modalities. The controversies in evaluation and management of SSIs in spine surgery will be reviewed.

Vertebral Osteomyelitis and Spinal Epidural Abscess: An Evidence-based Review.

Spinal infections have historically been associated with significant morbidity and mortality. Current treatment protocols have improved patient outcomes through prompt and accurate infection identification, medical treatment, and surgical interventions. Medical and surgical management, however, remains controversial because of a paucity of high-level evidence to guide decision making. Despite this, an awareness of presenting symptoms, pertinent risk factors, and common imaging findings are critical for treating spine infections. The purpose of this article is to review the recent literature and present the latest evidence-based recommendations for the most commonly encountered primary spinal infections: vertebral osteomyelitis and epidural abscess.

The effect of aging on posterior intertransverse lumbar fusion: a New Zealand white rabbit model.

STUDY DESIGN: In vivo assessment of lumbar spinal fusion between a younger and older cohort of New Zealand white rabbits. OBJECTIVE: Directly compare fusion within young and aged New Zealand white rabbits to establish an aged spinal fusion model translational research. SUMMARY OF BACKGROUND DATA: Prior studies have utilized skeletally mature young rabbits (6-12 mo old) that may not be appropriate as an analog for studying the aging human spine. METHODS: Ten aged (>36 mo old) and 10 young (12 mo old) New Zealand white rabbits underwent a single-level, bilateral, L5-6 posterolateral intertransverse fusion using autogenous iliac crest bone graft. The animals were killed at 6 weeks postoperatively, and the specimens were then evaluated with quantitative microcomputerized tomography and manual palpation by 6 orthopedic surgeons. The fusions were graded as either fused or not fused by each examiner. The spines were then embedded in poly(methyl methacrylate) and cut into 2-mm-thick sections for histologic analysis. RESULTS: A higher percentage of young rabbits were determined to be successfully fused through manual palpation testing compared with the aged rabbits. Micro-computed tomography (CT) analysis revealed a significantly greater fusion mass volume in the younger rabbits than in the older cohort. In addition, the fusion density of the younger rabbits was found to be significantly lower than that of the older rabbits when normalized to the bone density in the nonfused portion of the spine. Histologic analysis showed that the quality of the bone within the fusion mass was consistent between the young and old rabbits. A greater number of young animals had bilateral continuous bone graft compared with the aged animals. CONCLUSIONS: The aged (>36 mo) New Zealand white rabbit model appears to be a valid model to evaluate the effect of aging on lumbar fusion and has the potential to more accurately model conditions that are present in the older human spine.

Evaluation and treatment of spinal metastatic disease.

With the increased survival of oncologic patients, evaluation and management of patients with spinal metastasis is crucial to reducing morbidity and maximizing function. In this chapter, we present some guidelines for the initial systematic evaluation of patients with spinal lesions, as well as the risks, benefits, and alternatives to nonoperative and operative management of metastatic spinal disease, and the overall survival of these patients.