Rod-Screw Constructs Composed of Dissimilar Metals Do Not Affect Complication Rates in Posterior Fusion Surgery Performed for Adult Spinal Deformity.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The objective of this study was to compare implant-related complications between mixed-metal and same-metal rod-screw constructs in patients who underwent posterior fusion for adult spinal deformity. SUMMARY OF BACKGROUND DATA: Contact between dissimilar metals is discouraged due to potential for galvanic corrosion, increasing the risk for metal toxicity, infection, and implant failure. In spine surgery, titanium (Ti) screws are most commonly used, but Ti rods are notch sensitive and likely more susceptible to fracture after contouring for deformity constructs. Cobalt chrome (CC) and stainless steel (SS) rods may be suitable alternatives. No studies have yet evaluated implant-related complications among mixed-metal constructs (SS or CC rods with Ti screws). METHODS: Adults with spinal deformity who underwent at least 5-level thoracic and/or lumbar posterior fusion or 3-column osteotomy between January 2013 and May 2015 were reviewed, excluding neuromuscular deformity, tumor, acute trauma or infection. Implant-related complications included pseudarthrosis, proximal junctional kyphosis, hardware failure (rod fracture, screw pullout or haloing), symptomatic hardware, and infection. RESULTS: A total of 61 cases met inclusion criteria: 24 patients received Ti rods with Ti screws (Ti-Ti, 39%), 31 SS rods (SS-Ti, 51%), and 6 CC rods (CC-Ti, 9.8%). Median follow-up was 37-42 months for all groups. Because of the limited number of cases, the CC-Ti group was not included in statistical analyses. There were no differences between Ti-Ti and SS-Ti groups with regard to age, body mass index, or smokers. Implant-related complications did not differ between the Ti-Ti and SS-Ti groups (P=0.080). Among the Ti-Ti group, there were 15 implant-related complications (63%). In the SS-Ti group, there were 12 implant-related complications (39%). There were 3 implant-related complications in the CC-Ti group (50%). CONCLUSION: We found no evidence that combining Ti screws with SS rods increases the risk for implant-related complications.

Adult Lumbar Scoliosis: Nonsurgical Versus Surgical Management.

Adult spinal deformity has become an increasingly recognized condition, with a 32% incidence in the adult population and a 68% incidence in the elderly population. Often, patients with adult spinal deformity are initially offered nonsurgical treatment for their symptoms despite the lack of data to support its efficacy because of the high complication rate associated with surgical treatment in this age group. Determining which patients would benefit the most from nonsurgical versus surgical treatment remains a challenge. Limited evidence exists to support guidelines on the most effective way to treat patients with adult spinal deformity. Treatment decisions for patients with adult spinal deformity often rely on individual surgeon experience and patient preferences.

Risk Factors for Nonroutine Discharge in Patients Undergoing Spinal Fusion for Intervertebral Disc Disorders.

BACKGROUND: Although outcomes following spinal fusion for intervertebral disc disorders have been studied, factors influencing discharge disposition and health care resource utilization have not been determined. This study sought to clarify perioperative risk factors for non-routine discharge and prolonged hospital stay in patients undergoing fusion for intervertebral disc disorders. METHODS: The National Hospital Discharge Survey was queried to identify all patients discharged from U.S. hospitals following spinal fusion for intervertebral disc disorders between 1990 and 2007. A cohort representative of 1,943,707 patients was identified and separated into those who were discharged home and those who were discharged to rehabilitation facilities. Multivariable logistic regression analysis was used to identify independent predictors of non-routine discharge to another inpatient facility and prolonged hospital stay. RESULTS: The strongest risk factors for non-routine discharge were age>65 years, congestive heart failure, atrial fibrillation, any general in-hospital complication, diabetes mellitus, osteoporosis, hypertension and any surgery-related complication. Patients younger than 50 years and males had the lowest rate of non-routine discharge. The strongest risk factors for prolonged hospital stay were any surgery-related complication, congestive heart failure, any general in-hospital complication, atrial fibrillation, age > 65 years, osteoporosis and diabetes mellitus. Patients 36-50 years of age had the lowest risk of increased length of hospital stay. CONCLUSIONS: Knowledge of these risk factors may aid in better resource allocation and improved strategies for managing patients with spondylosis in order to decrease healthcare costs. LEVEL OF EVIDENCE: 3.

Outcomes of total joint arthroplasty in HIV patients.

BACKGROUND: Advancement in human immunodeficiency virus (HIV) therapies has increased life expectancy. The need for joint replacement is expected to increase as this population develops degenerative changes from aging and avascular necrosis (AVN). Studies have shown a higher risk of peri-prosthetic joint infections (PJI) in HIV patients. However, these studies include a high percentage of hemophiliacs, which may be a confounding variable. With the advent of highly active anti-retroviral therapy (HAART) and evolving HIV demographics, we hypothesize the rate of PJIs in HIV patients are comparable to the general population. METHODS: We performed a retrospective cohort study using prospectively collected data from our arthroplasty database. We identified 24 HIV patients that underwent 31 primary hip and one primary knee arthroplasty between July 1, 2000 and September 30, 2012. Mean age was 50 years (range 31-74). Mean follow-up was 14 months (range 1.5-60). RESULTS: There were no PJIs in our HIV population. All HIV patients were non-hemophiliacs on HAART. Thirty-one total hip arthroplasties (THA) and one total knee arthroplasty were performed. Twenty-one HIV patients underwent THA for AVN. Eight patients had bilateral AVN. One patient needed revision for aseptic loosening. The mean CD4 count was 647 (194-1193). Mean viral load was undetectable in 19 patients and unavailable in five. CONCLUSIONS: Our HIV population had a lower rate of PJI compared to infection rates in prior literature. Despite our limited patient population, our data suggests that well controlled HIV patients on HAART therapy with undetectable viral loads and CD4 >200 are at similar risk of PJI as the average population.

Case reviews of infections of the spine in patients with a history of solid organ transplantation.

STUDY DESIGN: Retrospective clinical case series. OBJECTIVE: To report on the epidemiological, microbiological, and clinical characteristics of spinal infections in patients who have undergone solid organ transplantation. SUMMARY OF BACKGROUND DATA: Spine infections remain a therapeutic challenge, particularly in patients who are immunocompromised. Solid organ transplant patients represent a growing population of immunocompromised hosts. To our knowledge, no previous reports have examined the clinical characteristics spinal infections in this at-risk population in a systematic fashion. METHODS: The records of patients with a history of solid organ transplantation from January 2007 through December 2012 were identified using Current Procedural Terminology procedure codes. Patients with spine infections who have received transplants were then identified using International Classification of Diseases, Ninth Revision codes for spine infection. In addition to demographic data, we recorded medical comorbidities, immunosuppressant medications, laboratory results, culture data, treatment received, and short-term results. RESULTS: During this 6-year period, 2764 solid organ transplants were performed at our institution. Of this cohort, 6 patients (0.22%) were treated for a spinal infection. Patient's age ranged from 51 to 80 years (mean, 63 yr). All spine infections occurred within 1 year after organ transplantation. All patients had an elevated erythrocyte sedimentation rate. Only 1 patient had an elevated white blood cell count. The most common organisms were Escherichia coli and Staphylococcus. Four patients required surgical treatment. All patients had complete resolution of symptoms. CONCLUSION: Our data suggest that patients with a history of solid organ transplantation may be more susceptible to developing spine infections than the general population. The most common organisms in our cohort were E. coli and Staphylococcus. Spine infections caused by atypical organisms do also occur in the organ transplant population, as is the case in other immunocompromised patients. The identification of these organisms and timely institution of treatment remains critical in the management of this at-risk population. LEVEL OF EVIDENCE: 4.

The kinematic relationships of the upper cervical spine.

STUDY DESIGN: A retrospective radiographic study. OBJECTIVE: To elucidate the kinematic relationships of the upper cervical spine. SUMMARY OF BACKGROUND DATA: To our knowledge, few reports have described the kinematic relationships of the upper cervical spine in patients with general age-related cervical spondylosis. METHODS: We performed Kinetic magnetic resonance imaging for 295 consecutive patients experiencing neck pain without neurologic symptoms. Subjects with rheumatoid arthritis, traumatic history, and severe degenerative changes in the upper cervical spine were excluded. Anterior atlantodens interval (AADI) and the cervicomedullary angle in 3 different postures were measured, and the variations in each value between flexion and neutral (F-N), neutral and extension (N-E), and flexion and extension (F-E) were calculated. The subjects were classified into 3 groups according to the space available for the cord values (A: or=15 mm). RESULTS: AADI significantly increased from extension to flexion posture, however, no significant differences were observed in every posture among the groups. F-N variation in AADI showed no significant differences among the groups; however, N-E variation between Groups A and C and between Groups B and C and F-E variation between Groups A and C showed significant differences. The cervicomedullary angle significantly increased from flexion to extension posture, however, no significant differences were observed in every posture among the groups. Angle variations among the groups showed no significant differences, except for F-N angle variation between Groups B and C. None of the variations in AADI and the cervicomedullary angle were significantly correlated. CONCLUSION: Our results suggest that only the kinematics of the atlantoaxial movement, especially the posterior movement, was greatly affected by the narrowing of space available for the cord. The central atlantoaxial joint may be closely related to the mechanisms for protecting the spinal cord by restriction of the atlantoaxial movement.

A porcine collagen-derived matrix as a carrier for recombinant human bone morphogenetic protein-2 enhances spinal fusion in rats.

BACKGROUND CONTEXT: Recombinant bone morphogenetic proteins (rhBMPs) have been used successfully in clinical trials. However, large doses of rhBMPs were required to induce adequate bone repair. Collagen sponges (CSs) have failed to allow a more sustained release of rhBMPs. Ongoing research aims to design carriers that allow a more controlled and sustained release of the protein. E-Matrix is a injectable scaffold matrix that may enhance rhBMP activity and stimulate bone regeneration. PURPOSE: The purpose of this study was to test E-Matrix as a carrier for rhBMPs in a CS and examine its feasibility in clinical applications by using a rat spinal fusion model. PATIENT SAMPLE: A total of 80 Lewis rats aged 8-16 weeks were divided into nine groups. STUDY DESIGN/SETTING: Rat spinal fusion model. OUTCOME MEASURES: Radiographs were obtained at 4, 6, and 8 weeks. The rats were sacrificed and their spines were explanted and assessed by manual palpation, high-resolution microcomputed tomography (micro-CT), and histologic analysis. METHODS: Group I animals were implanted with CS alone (negative control); Group II animals with CS containing 10microg rhBMP-2 (positive control); Group III animals with CS containing 3microg rhBMP-2; Group IV animals with CS containing 3microg rhBMP-2 and E-Matrix; Group V animals with CS containing 1microg rhBMP-2; Group VI animals with CS containing 1microg rhBMP-2 and E-Matrix; Group VII animals with CS containing 0.5microg rhBMP-2; Group VIII animals with CS containing 0.5microg rhBMP-2 and E-Matrix; and Group IX animals with CS and E-Matrix without rhBMP-2. RESULTS: Radiographic evaluation, micro-CT, and manual palpation revealed spinal fusion in all rats in the BMP-2 and E-Matrix groups (IV, VI, and VIII) and high-dose BMP-2 groups (II and III). Four spines in the 3microg rhBMP-2 group (V) fused, and one spine in the 0.5microg rhBMP-2 group (VII) exhibited fusion. No spines were fused in Groups I (CS alone) and IX (E-Matrix alone). The volume of new bone in the area between the tip of the L4 transverse process and the base of the L5 transverse process in Group IV was equivalent to the volumes observed in Group II. CONCLUSION: E-matrix enhances spinal fusion as a carrier for rhBMP-2 in a rat spinal fusion model. The results of this study suggest that E-Matrix as a growth factor carrier may be applicable to spinal fusion and may improve rhBMP-2's activity at the fusion site.