Employing direct electromagnetic coupling to assess acute fracture healing: An ovine model assessment.

OBJECTIVES: This study explored the efficacy of collecting temporal fracture site compliance data via an advanced direct electromagnetic coupling (DEC) system equipped with a Vivaldi-type antenna, novel calibration technique, and multi-antenna setup (termed maDEC) as an approach to monitor acute fracture healing progress in a translational large animal model. The overarching goal of this approach was to provide insights into the acute healing dynamics, offering a promising avenue for optimizing fracture management strategies. METHODS: A sample of twelve sheep, subjected to ostectomies and intramedullary nail fixations, was divided into two groups, simulating normal and impaired healing scenarios. Sequential maDEC compliance or stiffness measurements and radiographs were taken from the surgery until euthanasia at four or eight weeks and were subsequently compared with post-sacrifice biomechanical, micro-CT, and histological findings. RESULTS: The results showed that the maDEC system offered straightforward quantification of fracture site compliance via a multiantenna array. Notably, the rate of change in the maDEC-measured bending stiffness significantly varied between normal and impaired healing groups during both the 4-week (p = 0.04) and 8-week (p = 0.02) periods. In contrast, radiographically derived mRUST healing measurements displayed no significant differences between the groups (p = 0.46). Moreover, the cumulative normalized stiffness maDEC data significantly correlated with post-sacrifice mechanical strength (r2 = 0.80, p < 0.001), micro-CT measurements of bone volume fraction (r2 = 0.60, p = 0.003), and density (r2 = 0.60, p = 0.003), and histomorphometric measurements of new bone area fraction (r2 = 0.61, p = 0.003) and new bone area (r2 = 0.60, p < 0.001). CONCLUSIONS: These data indicate that the enhanced maDEC system provides a non-invasive, accurate method to monitor fracture healing during the acute healing phase, showing distinct stiffness profiles between normal and impaired healing groups and offering critical insights into the healing process's progress and efficiency.

Biomechanical specimen assessment by low dose biplanar X-ray study of fusion constructions using a posterior lumbar cage with integrated anchors and posterior adjunctive fixators.

The objective was to compare L4/5 range of motions of fusion constructs using anchored cages. Twelve human cadaveric spine were tested in intact condition, and divided into TLIF and PLIF groups. Testing consisted in applying pure moments in flexion-extension, lateral bending and axial rotation. The computation of intersegmental motion was assessed using 3 D biplanar radiographs. In TLIF group, the addition of contralateral transfacet decreased flexion-extension motion (39%; p = 0.036) but without difference with the ipsilateral pedicle screw construction (53%; p = 0.2). In PLIF group, the addition of interspinous anchor reduced flexion-extension motion (12%; p = 0.036) but without difference with the bilateral pedicle screw construction (17%; p = 0.8).

Predicting the Failure Risk of Internal Fixation Devices in Chinese Patients Undergoing Spinal Internal Fixation Surgery: Development and Assessment of a New Predictive Nomogram.

The current study is aimed at developing and validating a nomogram of the risk of failure of internal fixation devices in Chinese patients undergoing spinal internal fixation. We collected data from a total of 1139 patients admitted for spinal internal fixation surgery at the First Affiliated Hospital of Guangxi Medical University from May 2012 to February 2019. Of these, 1050 patients were included in the spinal internal fixation group and 89 patients in the spinal internal fixation device failure group. Patients were divided into training and validation tests. The risk assessment of the failure of the spinal internal fixation device used 14 characteristics. In the training test, the feature selection of the failure model of the spinal internal fixation device was optimized using the least absolute shrinkage and selection operator (LASSO) regression model. Based on the characteristics selected in the LASSO regression model, multivariate logistic regression analysis was used for constructing the model. Identification, calibration, and clinical usefulness of predictive models were assessed using C-index, calibration curve, and decision curve analysis. A validation test was used to validate the constructed model. In the training test, the risk prediction nomogram included gender, age, presence or absence of scoliosis, and unilateral or bilateral fixation. The model demonstrated moderate predictive power with a C-index of 0.722 (95% confidence interval: 0.644-0.800) and the area under the curve (AUC) of 0.722. Decision curve analysis depicted that the failure risk nomogram was clinically useful when the probability threshold for internal fixation device failure was 3%. The C-index of the validation test was 0.761. This novel nomogram of failure risk for spinal instrumentation includes gender, age, presence or absence of scoliosis, and unilateral or bilateral fixation. It can be used for evaluating the risk of instrumentation failure in patients undergoing spinal instrumentation surgery.

Time to Surgery for Unstable Thoracolumbar Fractures in Latin America-A Multicentric Study.

OBJECTIVE: We sought to identify delays for surgery to stabilize unstable thoracolumbar fractures and the main reasons for them across Latin America. METHODS: We reviewed the charts of 547 patients with type B or C thoracolumbar fractures from 21 spine centers across 9 Latin American countries. Data were collected on demographics, mechanism of trauma, time between hospital arrival and surgery, type of hospital (public vs. private), fracture classification, spinal level of injury, neurologic status (American Spinal Injury Association impairment scale), number of levels instrumented, and reason for delay between hospital arrival and surgical treatment. RESULTS: The sample included 403 men (73.6%) and 144 women (26.3%), with a mean age of 40.6 years. The main mechanism of trauma was falls (44.4%), followed by car accidents (24.5%). The most frequent pattern of injury was B2 injuries (46.6%), and the most affected level was T12-L1 (42.2%). Neurologic status at admission was 60.5% intact and 22.9% American Spinal Injury Association impairment scale A. The time from admission to surgery was >72 hours in over half the patients and over a week in >25% of them. The most commonly reported reasons for surgical delay were clinical instability (22.9%), lack of operating room availability (22.7%), and lack of hardware for spinal instrumentation (e.g., screws/rods) (18.8%). CONCLUSIONS: Timing for surgery in this sample of unstable fractures was over 72 hours in more than half of the sample and longer than a week in about a quarter. The main reasons for this delay were clinical instability and lack of economic resources. There is an apparent need for increased funding for the treatment of spinal trauma patients in Latin America.

Exploring trends in admissions and treatment for ankle fractures: a longitudinal cohort study of routinely collected hospital data in England.

BACKGROUND: Evidence on the most effective and cost-effective management of ankle fractures is sparse but evolving. A recent large RCT in older patients with unstable fractures found that management with close-contact-casting was functionally equivalent and more cost-effective than internal fixation. We describe temporal and geographic variation in ankle fracture management and estimate the potential savings if close-contact-casting was used more often in older patients. METHODS: Patients admitted to hospital in England between 2007/08 and 2016/17 with an ankle fracture were identified using routine hospital episode statistics. We tested whether the use of internal fixation, and the proportion of internal fixations using intramedullary implants, changed over time. We estimated the potential annual cost savings if patients aged 60+ years were treated with close-contact-casting rather than internal fixation, in line with emerging evidence. RESULTS: Over the 10-year period, there were 223,465 hospital admissions with a primary ankle fracture diagnosis. The incidence (per 100,000) of internal fixation was fairly consistent over time in younger (33.2 in 2007/08, 30.9 in 2016/17) and older (36.5 in 2007/08, 37.4 in 2016/17) patients. The proportion of internal fixations which used intramedullary implants increased in both age groups (17.0-19.5% < 60 years; 15.2-17.4% 60+ years). In 2016/17, the cost of inpatient hospital care for ankle fractures in England was over £63.1million. If 50% of older patients who had an internal fixation instead had close-contact-casting, we estimate that approximately £1.56million could have been saved. CONCLUSIONS: Despite emerging evidence that non-surgical and surgical management achieve equivalent functional outcomes in older patients, the rate of surgical fixation has remained relatively stable over the decade. The health service could achieve substantial savings if a higher proportion of older patients were treated with close-contact-casting, in line with recent evidence.

Assessment of Patient Outcomes and Proximal Junctional Failure Rate of Patients with Adult Spinal Deformity Undergoing Caudal Extension of Previous Spinal Fusion.

OBJECTIVE: This case series examined patients undergoing caudal extension of prior fusion without alteration of the prior upper instrumented vertebra (UIV) to assess patient outcomes and rates of proximal junctional kyphosis (PJK)/proximal junctional failure (PJF). METHODS: Patients eligible for 2-year minimum follow-up undergoing caudal extension of prior fusion with unchanged UIVs were identified. These patients were evaluated for PJK/PJF, and patient reported outcomes were recorded. RESULTS: In total, 40 patients were included. Mean follow-up duration was 2.2 ± 0.3 years. Patients in this cohort had poor preoperative sagittal alignment (pelvic incidence minus lumbar lordosis [PI-LL] 26.7°, T1 pelvic angle [TPA] 29.0°, sagittal vertical axis [SVA] 93.4 mm) and achieved substantial sagittal correction (ΔSVA -62.2 mm, ΔPI-LL -19.8°, ΔTPA -11.1°) after caudal extension surgery. At final follow-up, there was a 0% rate of PJF among patients undergoing caudal extension of previous fusion without creation of a new UIV, but 27.5% of patients experienced PJK. Patients experienced significant improvement in both the Oswestry Disability Index and Scoliosis Research Society-22r total score at 2 years postoperatively (P < 0.05). In total, 7.5% (n = 3) of patients underwent further revision, at an average of 1.1 ± 0.54 years after the surgery with unaltered UIV. All 3 of these patients underwent revision for rod fracture with no revisions for PJK/PJF. CONCLUSIONS: Patients undergoing caudal extension of previous fusions for sagittal alignment correction have high rates of clinical success, low revision surgery rates, and very low rates of PJF. Minimizing repetitive tissue trauma at the UIV may result in decreased PJF risk because the PJF rate in this cohort of patients with unaltered UIV is below historical PJF rates of patients undergoing sagittal balance correction.

Lengthening of magnetically controlled growing rods caused minimal pain in 25 children: pain assessment with FPS-R, NRS, and r-FLACC.

STUDY DESIGN: Descriptive case series. OBJECTIVE: The aim of the study is to investigate the pain associated with magnetically controlled growing rod (MCGR) lengthening procedures. MCGRs have gained popularity because they offer non-surgical lengthening procedures in early-onset scoliosis (EOS) instead of semi-annual open surgery elongations with traditional growing rods. Many aspects of MCGR treatment have been investigated, but pain in conjunction with distraction is only sparsely described in the literature. METHODS: Pain intensity was assessed in 25 EOS patients before, during and after MCGR lengthening procedures in an outpatient setup. They underwent at least two (range 2-16) lengthening procedures prior to this study. The pain intensity was estimated using patient-reported Faces Pain Scale (FPS-R), caregiver-reported pain numeric rating scale (NRS), and NRS and revised Face, Legs, Activity, Cry, Consolability scale (r-FLACC) by two medically trained observers. The inter-rater reliability and correlation between instruments were analyzed. RESULTS: 23 of 25 EOS patients (8- to 16-year old) with mixed etiology were able to self-report pain. The average pain intensity was mild: median 1 (range 0-6) on all four instruments on a 0-to-10 scale. Afterward, 22/25 patients (88%) were completely pain free and the remaining 3 patients had a pain score of 1. MCGR stalling (i.e. clunking) was encountered in 14/25 (56%) of the patients without impact on the pain intensity. CONCLUSIONS: The average maximum pain intensities during the lengthening procedures were mild and pain ceased within few minutes. The inter-rater reliability was good to excellent for NRS and r-FLACC, and there were high correlations between all the four pain instruments, indicating high criterion validity. LEVEL OF EVIDENCE: Level IV, case series.

Cost-Effectiveness of Magnetically Controlled Growing Rods: Who Really Benefits?

STUDY DESIGN: Retrospective case analysis. OBJECTIVES: Evaluate the cost difference between magnetically controlled growing rod (MCGR) and traditional growing rod (TGR) surgeries at initial implantation and determine the recipient of cost savings. SUMMARY OF BACKGROUND DATA: Treatment of early-onset scoliosis is challenging and costly, with growing rods (GRs) becoming a standard treatment. Although both effectively control deformity, TGR requires repeat surgical lengthening and MCGR does not. Previous cost analyses have suggested that MCGR results in lower overall cost after 3 years because of the elimination of repeat surgeries; however, the benefactor of these savings is unclear. METHODS: All patients who underwent initial GR implantation from May 2011 to January 2016 at a tertiary care children's hospital were included (37 cases: 16 MCGR and 21 TGR; 4 TGR to MCGR conversions). Financial information was analyzed including insurance provider, and amount billed to and reimbursed from payer. Charges at the time of implantation were divided into categories (surgery time, room/board, anesthesia, implant cost, lab, radiology, therapy, medications, neuromonitoring, operating room materials, and recovery room). Variables were compared using t-tests to determine differences overall and per category. RESULTS: The average overall charge for MCGR implantation was 1.5 times greater than TGR implementation (p = .04). Average charges were statistically similar across all categories, except implant costs, which were significantly higher for MCGR (MCGR: $31,621 vs. TGR: $8,966, p < .0001). The average percentage reimbursement of total charges were similar between surgeries (MCGR 43% vs. TGR 46%, p = .26). CONCLUSIONS: MCGR implantation has a significantly higher charge than TGR, secondary to the higher expense of MCGR implants. Despite this, total institutional reimbursement is similar between the two procedures. Although MCGRs have been shown to be "cost effective" after 3 years, our findings suggest health care institutions bear the cost of this new technology while payers gain the long-term financial benefit. LEVEL OF EVIDENCE: Level III, economic analysis.

Towards a Non-Invasive Technique for Healing Assessment of Internally Fixated Femur.

The lack of a quantitative method to adequately assess fractured bone healing that has undergone fixation limits prognostic capabilities on patients' optimal return to work. This paper addresses the use of vibrational analysis to monitor the state of healing of a plate-screw fixated femur and supplement the current clinical radiographic assessment. This experimental study involves an osteotomised composite femur specimen enclosed by modelling clay to simulate the damping effect of overlying soft tissues. Epoxy adhesives are applied to the fractured region and to simulate the healing process. With the instrumentation described, the cross-spectrum and coherence are obtained and analysed in the frequency domain over a period of time. The results suggest that it is crucial to analyse the cross-spectrum and proposed healing index to quantitatively assess the stages of healing. The results also show that the mass loading effect due to modelling clay did not influence the proposed healing assessment technique. The findings indicate a potential non-intrusive technique to evaluate the healing of fractured femur by utilising the vibrational responses.

Polyetheretherketone Rods in Lumbar Spine Degenerative Disease: Mid-term Results in a Patient Series Involving Radiological and Clinical Assessment.

AIM: To evaluate the satisfaction of patients operated due to degenerative lumbar spinal diseases with dynamic stabilization placing polyetheretherketone (PEEK) rods and to share their radiological and clinical results (mid-term) with visual analogue scale (VAS) and Oswestry disability index (ODI) scores. MATERIAL AND METHODS: The preoperative and postoperative low back pain, leg pain VAS and ODI scores of 172 patients who were operated for degenerative spinal diseases, were evaluated. Preoperative and postoperative lumbar lordosis were compared. The patients included to the study were evaluated postoperatively around the 2nd year with lumbar MRI by means of adjacent segment disease (ASD) and additional problems. RESULTS: A statistically but not radiologically-by means of sagittal profile reconstruction-significant increase in lumbar lordosis angle was achieved. Significant improvement was observed in the comparison of preoperative and postoperative period in the analysis of patients’ preoperative low back pain (p < 0.0001), and decompression-related leg pain VAS scores (p < 0.0001). Significant improvement was also observed in the ODI scores of the patients (p < 0.0001). Among 172 patients with dynamic stabilization, there were 10 patients who underwent reoperation (5.8%). CONCLUSION: Although it is statistically significant, it can be seen that the lumbar lordosis can not be corrected at significant degrees radiographically in the operations performed with the PEEK rod. Dynamic stabilization with PEEK rod is insufficient for sagittal correction, but the mid-term results reached satisfactory reoperation rates clinically outcomes. Rate of ASD is quite low in stabilization with PEEK rod.

Costs and Radiographic Outcomes of Rotational Ankle Fractures Treated by Orthopaedic Surgeons With or Without Trauma Fellowship Training.

INTRODUCTION: We evaluated the radiographic outcomes and surgical costs of surgically treated rotational ankle fractures in our health system between providers who had completed a trauma fellowship and those who had not. METHODS: We grouped patients into those treated by trauma-trained orthopaedic surgeons (TTOS) and non-trauma-trained orthopaedic surgeons (NTTOS). We graded the quality of fracture reductions and calculated implant-related costs of treatment. RESULTS: A total of 208 fractures met the inclusion criteria, with 119 in the TTOS group and 89 in the NTTOS group. Five patients lost reduction during the follow-up period. The adequacy of fracture reduction at final follow-up did not differ (P = 0.29). The median surgical cost was $2,940 for the NTTOS group and $1,233 for the TTOS group (P < 0.001). DISCUSSION: We found no notable differences in radiographic outcomes between the TTOS and NTTOS groups. Cost analysis demonstrated markedly higher implant-related costs for the NTTOS group, with the median surgical cost being more than twice that for the TTOS group. LEVEL OF EVIDENCE: Level III.

A comparison of a self-locking stand-alone cage and anterior cervical plate for ACDF: Minimum 3-year assessment of radiographic and clinical outcomes.

OBJECTIVES: The self-locking stand-alone cage has been clinically applied in treating cervical degenerative disc disease (CDDD). However, no long-term clinical and radiographic studies have been performed so far. This retrospective study was designed to analyze and compare the efficacy and outcomes of anterior cervical discectomy and fusion (ACDF) using self-locking stand-alone cages and cages with the anterior cervical plating system. PATIENTS AND METHODS: A total of 98 consecutive patients were recruited in this study. Patients in the cage group were given stand-alone self-locking cages, and patients in the plate group were treated with cages and anterior plate fixation. The operative time, intraoperative blood loss and complications were recorded. Clinical outcomes were evaluated using the JOA scoring system, Neck Disability Index and Odom's criteria. The cervical lordosis, subsidence and cervical fusion status were assessed by X-ray and computed tomography. RESULTS: The mean follow-up period was 39.7 months in the cage group and 42.2 months in the plate group. The operative time, intraoperative blood loss, postoperative dysphagia, sore throat and adjacent segment degeneration in the cage group were significantly less than those in the plate group (p < 0.05). All the patients in both groups achieved complete interbody fusion. Postoperative JOA and NDI scores in both groups were obviously improved compared with the preoperative ones. The postoperative cervical lordosis was effectively restored in both groups. CONCLUSIONS: The self-locking stand-alone cage for ACDF could effectively restore the cervical physiological curvature, cause few complications, and lead to satisfactory outcomes. Therefore, it could be used as an effective and reliable treatment for the CDDD.

Radiopaque UHMWPE sublaminar cables for spinal deformity correction: Preclinical mechanical and radiopacifier leaching assessment.

Polymeric sublaminar cables have a number of advantages over metal cables in the field of spinal deformity surgery, with decreased risk of neurological injury and potential for higher correction forces as the two most predominant. However, currently available polymer cables are radiolucent, precluding postoperative radiological assessment of instrumentation stability and integrity. This study provides a preclinical assessment of a woven UHMWPE cable made with radiopaque UHMWPE fibers. Our primary goal was to determine if the addition of a radiopacifier negatively affects the mechanical properties of UHMWPE woven cables. Tensile mechanical properties were determined and compared to suitable controls. Radiopacity was evaluated and radiopacifier leaching was assessed in vitro and in vivo. Finally, in vivo bismuth organ content was quantified after a 24-week implantation period in sheep. Results show that the mechanical properties of woven UHMWPE cables were not deleteriously affected by the addition of homogenously dispersed bismuth oxide particles within each fiber. Limited amounts of bismuth oxide were released in vitro, well below the toxicological threshold. Tissue concentrations lower than generally accepted therapeutic dosages for use against gastrointestinal disorders, well below toxic levels, were discovered in vivo. These results substantiate controlled clinical introduction of these radiopaque UHMWPE cables. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 771-779, 2018.

A cost-utility analysis of Dynesys dynamic stabilization versus instrumented fusion for the treatment of degenerative lumbar spine diseases.

BACKGROUND: Symptomatic chronic low back and leg pain resulting from lumbar spine degenerative disorders is highly prevalent in China, and for some patients, surgery is the final option for improvement. Several techniques for spinal non-fusion have been introduced to reduce the side-effects of fusion methods and hasten postoperative recovery. In this study, the authors have evaluated the cost-effectiveness of Dynesys posterior dynamic stabilization system (DY) compared with lumbar fusion techniques in the treatment of single-level degenerative lumbar spinal conditions. METHODS: A total of 221 patients undergoing single-level elective primary surgery for degenerative lumbar pathology were included. 2-Year postoperative health outcomes of Visual Analogue Scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36) and EuroQol-5 Dimensions (EQ-5D) questionnaires were recorded. 2-Year back-related medical resource use, missed work, and health-state values (Quality-adjusted life-year [QALY]) were assessed. Cost-effectiveness was determined by the incremental cost per QALY gained. RESULTS: At each follow-up point, both cohorts were associated with significant improvements in VAS scores, ODI, SF-36 scores and EQ-5D QALY scores, which persisted at the 2-year evaluation. The 2-year total mean cost per patient were significantly lower for Dynesys system ($20,150) compared to fusion techniques ($25,581, $27,862 and $27,314, respectively) (P < 0.001). Using EQ-5D, the mean cumulative 2-year QALYs gained were statistically equivalent between the four groups (0.28, 0.27, 0.30 and 0.30 units, respectively) (P = 0.74). Results indicate that patients implanted with the DY system derive lower total costs and more utility, on average, than those treated with fusion. CONCLUSIONS: The Dynesys dynamic stabilization system is cost effective compared to instrumented lumbar fusion for treatment of single-level degenerative lumbar disorders. It is not possible to state whether DY or lumbar fusion is more cost-effective after 2 years.

Magnetically controlled growing rods in the treatment of early-onset scoliosis: a note of caution.

The MAGnetic Expansion Control (MAGEC) system is used increasingly in the management of early-onset scoliosis. Good results have been published, but there have been recent reports identifying implant failures that may be associated with significant metallosis surrounding the implants. This article aims to present the current knowledge regarding the performance of this implant, and the potential implications and strategies that may be employed to identify and limit any problems. We urge surgeons to apply caution to patient and construct selection; engage in prospective patient registration using a spine registry; ensure close clinical monitoring until growth has ceased; and send all explanted MAGEC rods for independent analysis. The MAGEC system may be a good instrumentation system for the treatment of early-onset scoliosis. However, it is innovative and like all new technology, especially when deployed in a paediatric population, robust systems to assess long-term outcome are required to ensure that patient safety is maintained. Cite this article: Bone Joint J 2017;99-B:708-13.

A Prospective Randomized Trial to Assess Fixation Strategies for Severe Open Tibia Fractures: Modern Ring External Fixators Versus Internal Fixation (FIXIT Study).

The treatment of high-energy open tibia fractures is challenging in both the military and civilian environments. Treatment with modern ring external fixation may reduce complications common in these patients. However, no study has rigorously compared outcomes of modern ring external fixation with commonly used internal fixation approaches. The FIXIT study is a prospective, multicenter randomized trial comparing 1-year outcomes after treatment of severe open tibial shaft fractures with modern external ring fixation versus internal fixation among men and women of ages 18-64. The primary outcome is rehospitalization for major limb complications. Secondary outcomes include infection, fracture healing, limb function, and patient-reported outcomes including physical function and pain. One-year treatment costs and patient satisfaction will be compared between the 2 groups, and the percentage of Gustilo IIIB fractures that can be salvaged without soft tissue flap among patients receiving external fixation will be estimated.

Magnetically controlled growing rods for scoliosis surgery.

INTRODUCTION: Early onset scoliosis can be both a disfiguring as well as a life threatening condition. When more conservative treatments fail, pediatric spinal surgeons are forced to consider operative interventions. Traditionally, these interventions have involved the insertion of a variety of implants into the patient with a limited number of anchor points controlling the spine. In the past, these pediatric patients have had multiple surgeries for elective lengthening of these devices to facilitate their growth while attempting to control the scoliosis. These patients often experience a physical and emotional toll from their multiple repeated surgeries. Growing spine techniques have also had a noted high complication rate due to implant dislodgement and infections. Recently, the development of non-invasively, self-lengthening growing rods has occurred. These devices have the potential to allow for the devices to be lengthened magnetically in a conscious patient in the surgeon's office. Areas covered: This review summarized previously published articles in the English literature using a key word search in PubMed for: 'magnetically controlled growing rods', 'Magec rods', 'magnetic growing rods' and 'growing rods'. Expert commentary: Magnetically controlled growing rods have an advantage over growing rods in lengthening the growing spine in the absence of repetitive surgeries.

Metals in Spine.

The treatment of spinal disorders requires the consideration of a number of factors and understanding the type of material we are implanting is important. Alloys have different mechanical properties and behave differently under different physiologic conditions. Spinal implants need to have good performance in the characteristics of biofunctionality and biocompatibility. In this review, the alloys titanium, cobalt-chrome, nitinol, and tantalum will be examined closely. Several of the important properties that are considered when selecting an alloy for use in spinal instrumentation are explored and detailed for each. This allows for an assessment and comparison of each alloy and a possible determination of which is the best alloy for specific surgery or the best alloy for use in specific situations.

Assessment of magnetic field interactions and radiofrequency-radiation-induced heating of metallic spinal implants in 7 T field.

The safety of metallic spinal implants in magnetic resonance imaging (MRI) performed using ultrahigh fields has not been established. Hence, we examined whether the displacement forces caused by a static magnetic field and the heating induced by radiofrequency radiation are substantial for spinal implants in a 7 T field. We investigated spinal rods of various lengths and materials, a screw, and a cross-linking bridge in accordance with the American Society for Testing and Materials guidelines. The displacement forces of the metallic implants in static 7 T and 3 T static magnetic fields were measured and compared. The temperature changes of the implants during 15-min-long fast spin-echo and balanced gradient-echo image acquisition sequences were measured in the 7 T field. The deflection angles of the metallic spinal materials in the 7 T field were 5.0-21.0° [median: 6.7°], significantly larger than those in the 3 T field (1.0-6.3° [2.2°]). Among the metallic rods, the cobalt-chrome rods had significantly larger deflection angles (17.8-21.0° [19.8°]) than the pure titanium and titanium alloy rods (5.0-7.7° [6.2°]). The temperature changes of the implants, including the cross-linked rods, were 0.7-1.0°C [0.8°C] and 0.6-1.0°C [0.7°C] during the fast spin-echo and balanced gradient-echo sequences, respectively; these changes were slightly larger than those of the controls (0.4-1.1°C [0.5°C] and 0.3-0.9°C [0.6°C], respectively). All of the metallic spinal implants exhibited small displacement forces and minimal heating, indicating that MRI examinations using 7 T fields may be performed safely on patients with these implants. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1831-1837, 2017.

An assessment of outcomes with intramedullary fixation of fractured ribs.

BACKGROUND: Surgical management of fractured ribs with internal fixation is an increasingly accepted therapy. Concurrently, specific rib fixation prostheses are being developed which should improve results and minimise hardware and rib/splint construct failures. The Synthes titanium intramedullary splint lends itself to difficult to access areas such as posterior rib fractures and fractures under the scapula. We analyse a case series of patients in whom this rib fixation prosthesis has been used. METHODS: Fifteen patients received 35 intramedullary splints. Follow up at 3 and 6 months was performed with three dimensional computed tomography scanning to assess for bone alignment, callus formation and healing, residual deformity, hardware failure or cut through. Computerized finite element analysis (FEA) was used to model forces acting on a posterior fracture with and without an intramedullary fixation splint in situ. RESULTS: Complete healing (bony union) was noted in only 3 (9 %) of the fractures fixed with splints by 3 months. Partial healing (cartilaginous union) was noted in 28 of the 33 fractures (85 %), and non healing was noted in only 2 (6 %). In both those two patients, failure at the rib / splint interface was noted after both patients reported sneezing. No hardware failures were noted. By 6 months the fractures which had shown partial healing, had all completely healed. There were no late failures (between 3 and 6 months) of either hardware or rib/splint interfaces. FEA modelling identified sites of increased stress in the rib at the rib / splint interface and in a modelled intramedullary splint where it spans the fracture. CONCLUSIONS: Further analysis of outcomes with intramedullary splints is warranted as well as further development of intramedullary rib fixation solutions.