Posterior instrumented fusion surgery for adult spinal deformity: Correction rate and total balance.

BACKGROUND: The primary radiological goal of surgery for adult spinal deformity (ASD) is the restoration of lumbar lordosis (LL). Radiological parameters were analyzed to determine the surgical indications for ASD using posterior side-loading spinal instrumentation system. MATERIALS AND METHODS: This retrospective study included 31 patients of ASD who underwent posterior instrumented fusion surgery. Imaging parameters included spinal tilt angle (STA), LL, and thoracic kyphosis (TK). The ideal LL was estimated based on the normal value. RESULTS: Of 16 patients with sagittal imbalance, 10 patients demonstrated sagittal balance postoperatively. All six patients with frontal imbalance showed frontal balance postoperatively. STA improvement well correlated with change of LL. On univariate analysis, preoperative TK was significantly associated with preoperative sagittal imbalance and postoperative lack of LL with postoperative sagittal imbalance. CONCLUSIONS: The surgical concept of ASD focusing on correction of LL was demonstrated. Although the surgery of ASD is still challenging, posterior instrumented fusion surgery using posterior side-loading system may be well applied for mild or moderate ASD without hyper-TK. The posterior side-loading system is practical and can be one of the surgical choices.

Stand-alone ALIF with integrated intracorporeal anchoring plates in the treatment of degenerative lumbar disc disease: a prospective study on 65 cases.

PURPOSE: ALIF with cages is expected to restore disc height and stabilize the spine promoting fusion, while avoiding damage attributed to rod-pedicle screw fixation. However, it may be related to an increased risk of fusion failure and subsidence. A prospective study was conducted by five investigators across three centers to confirm performance of a PEEK cage for stand-alone ALIF in the treatment of lumbar degenerative disc disease (DDD). METHODS: Sixty-five patients, with back ± leg pain, requiring surgery for DDD, were included. Efficacy and safety were evaluated at 6 weeks, 3, 6, and 12 months post-operatively. Fusion and subsidence were assessed through CT-images at 12-month follow-up. Disc height was measured. Clinical outcomes included back and leg pain (VAS), disability (Oswestry Disability Index), Quality of Life (Short-Form 36), and adverse events. RESULTS: The fusion and the subsidence rates were 96.3 and 2.0 %, respectively. ALIF surgery restored anterior and posterior disc height compared to baseline. There were no device-related serious adverse events, and no revision surgeries. Clinical outcomes improved significantly through 12-month follow-up. CONCLUSION: Safety and efficacy of this stand-alone cage with integrated intracorporeal plates was confirmed through 12 months for treatment of degenerative conditions. The design of the cage and plates may contribute to the decreased subsidence rate observed.

Effect of adding bone marrow to ceramic graft materials with different interconnectivities in lumbar arthrodesis : quantification of bone formation.

INTRODUCTION: Combining bone marrow (BM) with graft materials can stimulate bone healing. However, bone growth is not quantified in most studies, and the influence of the rate of interconnectivity of ceramics loaded with bone marrow has not yet been quantified. Here, a rabbit model of posterolateral intertransverse arthrodesis was used to quantify the effect of adding BM to partially (PIC) or totally (TIC) interconnected ceramics. MATERIALS AND METHODS: A single lumbar level was grafted on two sides with TIC (n = 12) or PIC (n = 18). The ceramic was loaded with 1.5 ml of BM on one side (chosen at random). The fusion rate was assessed by manual palpation test. Bone formation was quantified on scanning electron microscopy images and by dual-energy X-ray absorptiometry. RESULTS: At week 6, bone formation with TIC was twice as high as that with PIC. When BM was added, 35.1 and 87.8 % more bone formation was observed in the TIC and PIC, respectively. In ceramics loaded with BM, the bone mineral density was significantly higher than that in ceramics alone. CONCLUSIONS: Differences in interconnectivity within the family of biphasic ceramics should be taken into account when applying them clinically. BM increased bone formation regardless of the type of ceramic employed.

Induction of osteogenesis in mesenchymal stem cells by activated monocytes/macrophages depends on oncostatin M signaling.

Bone resorption by osteoclasts and bone formation by osteoblasts are tightly coupled processes implicating factors in TNF, bone morphogenetic protein, and Wnt families. In osteoimmunology, macrophages were described as another critical cell population regulating bone formation by osteoblasts but the coupling factors were not identified. Using a high-throughput approach, we identified here Oncostatin M (OSM), a cytokine of the IL-6 family, as a major coupling factor produced by activated circulating CD14+ or bone marrow CD11b+ monocytes/macrophages that induce osteoblast differentiation and matrix mineralization from human mesenchymal stem cells while inhibiting adipogenesis. Upon activation of toll-like receptors (TLRs) by lipopolysaccharide or endogenous ligands, OSM was produced in classically activated inflammatory M1 and not M2 macrophages, through a cyclooxygenase-2 and prostaglandin-E2 regulatory loop. Stimulation of osteogenesis by activated monocytes/macrophages was prevented using neutralizing antibodies or siRNA to OSM, OSM receptor subunits gp130 and OSMR, or to the downstream transcription factor STAT3. The induced osteoblast differentiation program culminated with enhanced expression of CCAAT-enhancer-binding protein δ, Cbfa1, and alkaline phosphatase. Overexpression of OSM in the tibia of mice has led to new bone apposition with no sign of bone resorption. Two other cytokines have also a potent role in bone formation induced by monocytes/macrophages and activation of TLRs: IL-6 and leukemia inhibitory factor. We propose that during bone inflammation, infection, or injury, the IL-6 family signaling network activated by macrophages and TLR ligands stimulates bone formation that is largely uncoupled from bone resorption and is thus an important target for anabolic bone therapies.

Effects of lumbar artificial disc design on intervertebral mobility: in vivo comparison between mobile-core and fixed-core.

Although in theory, the differences in design between fixed-core and mobile-core prostheses should influence motion restoration, in vivo kinematic differences linked with prosthesis design remained unclear. The aim of this study was to investigate the rationale that the mobile-core design seems more likely to restore physiological motion since the translation of the core could help to mimic the kinematic effects of the natural nucleus. In vivo intervertebral motion characteristics of levels implanted with the mobile-core prosthesis were compared with untreated levels of the same population, levels treated by a fixed-core prosthesis, and normal levels (data from literature). Patients had a single-level implantation at L4L5 or L5S1 including 72 levels with a mobile-core prosthesis and 33 levels with a fixed-core prosthesis. Intervertebral mobility characteristics included the range of motion (ROM), the motion distribution between flexion and extension, the prosthesis core translation (CT), and the intervertebral translation (VT). A method adapted to the implanted segments was developed to measure the VT: metal landmarks were used instead of the bony landmarks. The reliability assessment of the VT measurement method showed no difference between three observers (p < 0.001), a high level of agreement (ICC = 0.908) and an interobserver precision of 0.2 mm. Based on this accurate method, this in vivo study demonstrated that the mobile-core prosthesis replicated physiological VT at L4L5 levels but not at L5S1 levels, and that the fixed-core prosthesis did not replicate physiological VT at any level by increasing VT. As the VT decreased when the CT increased (p < 0.001) it was proven that the core mobility minimized the VT. Furthermore, some physiologic mechanical behaviors seemed to be maintained: the VT was higher at implanted the L4L5 level than at the implanted L5S1 level, and the CT appeared lower at the L4L5 level than at the L5S1 level. ROM and motion distribution were not different between the mobile-core prosthesis and the fixed-core prosthesis implanted levels. This study validated in vivo the concept that a mobile-core helps to restore some physiological mechanical characteristics of the VT at the implanted L4L5 level, but also showed that the minimizing effect of core mobility on the VT was not sufficient at the L5S1 level.

Does core mobility of lumbar total disc arthroplasty influence sagittal and frontal intervertebral displacement? Radiologic comparison with fixed-core prosthesis.

BACKGROUND: An artificial disc prosthesis is thought to restore segmental motion in the lumbar spine. However, it is reported that disc prosthesis can increase the intervertebral translation (VT). The concept of the mobile-core prosthesis is to mimic the kinematic effects of the migration of the natural nucleus and therefore core mobility should minimize the VT. This study explored the hypothesis that core translation should influence VT and that a mobile core prosthesis may facilitate physiological motion. METHODS: Vertebral translation (measured with a new method presented here), core translation, range of motion (ROM), and distribution of flexion-extension were measured on flexion-extension, neutral standing, and lateral bending films in 89 patients (63 mobile-core [M]; 33 fixed-core [F]). RESULTS: At L4-5 levels the VT with M was lower than with F and similar to the VT of untreated levels. At L5-S1 levels the VT with M was lower than with F but was significantly different compared to untreated levels. At M levels a strong correlation was found between VT and core translation; the VT decreases as the core translation increases. At F levels the VT increases as the ROM increases. No significant difference was found between the ROM of untreated levels and levels implanted with either M or F. Regarding the mobility distribution with M and F we observed a deficit in extension at L5-S1 levels and a similar distribution at L4-5 levels compared to untreated levels. CONCLUSION: The intervertebral mobility was different between M and F. The M at L4-5 levels succeeded to replicate mobility similar to L4-5 untreated levels. The M at L5-S1 succeeded in ROM, but failed regarding VT and mobility distribution. Nevertheless M minimized VT at L5-S1 levels. The F increased VT at both L4-5 and L5-S1. CLINICAL RELEVANCE: This study validates the concept that the core translation of an artificial lumbar disc prosthesis minimizes the VT.

Mesenchymal stem cells induce a weak immune response in the rat striatum after allo or xenotransplantation.

Mesenchymal stem cells (MSCs) have attracted attention for their potential use in regenerative medicine such as brain transplantation. As MSCs are considered to be hypoimmunogenic, transplanted MSCs should not trigger a strong host inflammatory response. To verify this hypothesis, we studied the brain immune response after transplantation of human or rat MSCs into the rat striatum and MSC fate at days 5, 14, 21 and 63 after transplantation. Flow cytometry analysis indicated that both MSCs express CD90 and human leucocyte antigen (MHC) class I, but no MHC class II molecules. They do not express CD45 or CD34 antigens. However, MSC phenotype varies with passage number. Human MSCs have mRNAs for interleukin (IL)-6, IL-8, IL-12, tumour necrosis factor (TNF)-alpha and TGF-beta(1), whereas rat MSCs express IL-6-, IL-10-, IL-12- and TGF-beta(1)-mRNAs. The quantification shows higher levels of mRNAs for the anti-inflammatory molecules IL-6 and TGF-beta(1) than for pro-inflammatory cytokines IL-8 and IL-12; ELISA analysis showed no IL-12 whereas TGF-beta(1) and IL-6 were detected. Transplant size did not significantly vary between 14 and 63 days after transplantation, indicating an absence of immune rejection of the grafts. Very few mast cells and moderate macrophage and microglial infiltrations, observed at day 5 remained stable until day 63 after transplantation in both rat and human MSC grafts. The observations of very few dendritic cells, T alphabeta-cells, and no T gammadelta-lymphocytes, all three being associated with Tp rejection in the brain, support the contention that MSCs are hypoimmunogenic. Our results suggest that MSCs are of great interest in regenerative medicine in a (xeno)transplantation setting.

Epidural analgesia after scoliosis surgery: electrophysiologic and clinical assessment of the effects of bupivacaine 0.125% plus morphine versus ropivacaine 0.2% plus morphine.

STUDY OBJECTIVE: To study the electrophysiologic and clinical effects of epidural morphine combined with either bupivacaine 0.125% or ropivacaine 0.2%. DESIGN: Comparative, randomized, double-blind study. SETTINGS: Intensive care unit and hospital ward of a university hospital. PATIENTS: 18 adult ASA physical status I and II patients with degenerative or idiopathic scoliosis, undergoing posterior spinal fusion with instrumentation. INTERVENTIONS: Patients received epidural administration of 10-mL bolus of either bupivacaine or ropivacaine followed by a 6-mL/h infusion for 48 hours of unlabeled local anesthetic. In all patients, epidural morphine 5 mg was added daily. MEASUREMENTS: Assessment was focused mainly on somatosensory cortical evoked potentials, soleus H-reflex, and F waves. These electrophysiologic data were recorded before and after epidural medications. Second, respiratory rate, Paco(2), visual analog score (VAS), and side effects such as postoperative nausea and vomiting (PONV), gastrointestinal (GI) transit delay, and urinary retention were noted. MAIN RESULTS: Bupivacaine 0.125% + morphine was given to 9 patients, and ropivacaine 0.2% + morphine was given to 9 other patients. H-reflex, F waves, and somatosensory cortical evoked potential recording remained unchanged across the time of assessment. Respiratory rate and Paco(2) values were normal. VASs were indifferently low at rest, but they were lower with bupivacaine than with ropivacaine on mobilization. The frequency of PONV was indifferently high. No altered GI transit or urinary retention was noted. CONCLUSION: After epidural administration during the study conditions, bupivacaine 0.125% and ropivacaine 0.2% combined with morphine allow for neurologic examination.

Contribution of centralization phenomenon to the diagnosis, prognosis, and treatment of diskogenic low back pain.

The centralization phenomenon is the migration of low back and/or radiating pain to the spinal midline in response to specific positions or movements, for instance during a McKenzie mechanical assessment. However, differences in the definition of the centralization phenomenon occur across studies, most notably regarding the smallest required change in pain location and the time to centralization. Standardized criteria would be useful. Available data fail to establish that centralization is sufficiently specific of diskogenic pain as to obviate the need for investigations, particularly in patients considered for surgical treatment (e.g., fusion or implant). Although centralization correlates strongly with a positive diskography, the value of this last finding as a sign of diskogenic pain or an indicator that surgery is needed remains highly controversial. Nevertheless, centralization may indicate a high likelihood of diskogenic pain and may provide therapeutic guidance. Because centralization is associated with better outcomes after nonsurgical treatment, even in patients with nerve root pain, its presence may constitute an argument against surgical treatment. Finally, the McKenzie assessment may induce pain relief, albeit to a modest extent and for no longer than 3 months.

The vertebral interbody grafting site's low concentration in osteogenic progenitors can greatly benefit from addition of iliac crest bone marrow.

The ability of bone substitutes to promote bone fusion is contingent upon the presence of osteoinductive factors in the bone environment at the fusion site. Osteoblast progenitor cells are among these environmental osteoinductive factors, and one of the most abundant and available sources of osteoblastic cells is the bone marrow. As far as biological conditions are concerned, the vertebral interbody space appears as a favorable site for fusion, as it is surrounded by spongy bone, theoretically rich in osteogenic cells. This site may, however, not be as rich in osteogenic precursor cells especially at the time of grafting, because decortication of the vertebral end plates during the grafting process may modify cell content of the surrounding spongy bone. We tested this hypothesis by comparing the abundance of human osteogenic precursor cells in bone marrow derived from the iliac crest, the vertebral body, and the decorticated intervertebral body space. The number of potential osteoblast progenitors in each site was estimated by counting the alkaline phosphatase-expressing colony-forming units (CFU-AP). The results, however, demonstrate that the vertebral interbody space is actually poorer in osteoprogenitor cells than the iliac crest (P<0.001) and vertebral body (P<0.01), especially at the time of graft implantation. In light of our results, we advocate addition of iliac crest bone marrow aspirate to increase the success rate of vertebral interbody fusion.

Revision total hip arthroplasty performed after fracture of a ceramic femoral head. A multicenter survivorship study.

BACKGROUND: The alumina ceramic femoral head was introduced for total hip arthroplasty approximately thirty years ago. One of its main drawbacks was the risk of implant fracture. The aim of this study was to examine the results of revision total hip replacement performed specifically to treat a fracture of a ceramic femoral head and to identify technical factors that affected the outcomes. METHODS: One hundred and five surgical revisions to treat a fracture of a ceramic femoral head, performed at thirty-five institutions, were studied. The patients were examined clinically by the operating surgeon at the time of the last follow-up. The surgeon provided the latest follow-up radiographs, which were compared with the immediate postoperative radiographs. The success of the revisions was assessed with Kaplan-Meier survivorship analysis, with the need for repeat revision as the end point. We evaluated the complication rate and radiographic changes indicative of implant loosening. The average duration of follow-up between the index revision and the last clinical and radiographic review was 3.5 years (range, six months to twenty years). RESULTS: Following the revisions, radiographic evidence of cup loosening was seen in twenty-two hips (21%) and radiographic evidence of femoral loosening was seen in twenty-two (21%). One or several repeat revisions were necessary in thirty-three patients (31%) because of infection (four patients), implant loosening (twenty), osteolysis (eight), or fracture of the revision femoral head component (one). The survival rate at five years was 63% (95% confidence interval, 51% to 75%). The survival rate was significantly worse when the cup had not been changed, when the new femoral head was made of stainless steel, when a total synovectomy had not been done, and when the patient was less than fifty years old. CONCLUSIONS: Fracture of a ceramic femoral head component is a rare but potentially serious event. A suitable surgical approach, including total synovectomy, cup exchange, and insertion of a cobalt-chromium or new ceramic femoral ball minimizes the chance of early loosening of the implants and the need for one or more repeat revisions. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series [no, or historical, control group]).

Surgical treatment of idiopathic scoliosis in adults: an age-related analysis of outcome.

STUDY DESIGN: A retrospective outcome study was conducted. OBJECTIVE: To analyze the clinical and radiographic outcome of surgical treatment for idiopathic scoliosis in patients treated at the age of 20 years or older. SUMMARY OF BACKGROUND DATA: Idiopathic scoliosis continues to pose problems in many patients after adolescence. Surgical treatment of idiopathic scoliosis in adults still is a challenging subject, but no outcome analysis in terms of different age groups had been performed. METHODS: In this study, 58 adult patients with idiopathic scoliosis who underwent surgery using Cotrel-Dubousset instrumentation were followed up for 2 to 7 years, and the results were studied clinically and radiographically. RESULTS: The prevalence of pain that requires specific treatment decreased from 16% to 5%, and the pain improvement was reliably obtained in the older patients. Radiographically, the mean rate of Cobb angle correction was 53% for both the thoracic and lumbar curves, whereas it decreased age dependently, especially in relation to the thoracic curve. The sagittal plane correction generally was satisfactory in patients younger than 50 years, but appropriate lumbar lordosis was difficult to maintain after the age of 50 years. Frontal and sagittal balance often was difficult to achieve in patients older than 50 years. CONCLUSIONS: This study clarified specific characteristics and problems in the surgical treatment of adult idiopathic scoliosis according to different age groups. Although pain was the most important indication for surgery in patients older than 40 years, it was improved reliably by surgery in most of these patients. On the other hand, the radiographic results tended to be less satisfactory in the older patients in an age-dependent manner. These results provide useful information concerning the indications and strategies of adult scoliosis surgery.

Combined spinal cord monitoring using neurogenic mixed evoked potentials and collision techniques.

STUDY DESIGN: Neurogenic mixed evoked potentials are used routinely to monitor the spinal cord during spine surgery. This study investigates the differential sensory-motor contribution by using collision techniques. OBJECTIVE: To demonstrate that neurogenic mixed evoked potentials do contain a motor component. SUMMARY OF BACKGROUND DATA: Spinal cord monitoring is now routinely used during spine deformity surgery. Neurogenic mixed evoked potentials (i.e., potentials recorded from lower limb nerves after spinal cord stimulation) represent a reliable and sensitive technique. However, their specificity (sensory and motor spinal pathways) remains debated. METHODS: Neurogenic mixed evoked potentials and collisions were performed in 24 consecutive patients during scoliosis surgery. Neurogenic mixed evoked potentials were elicited by a high thoracic spinal test stimulation and recorded from the tibial nerve at the ankle. A peripheral conditioning stimulation was delivered at the popliteal fossa 15 ms before spinal stimulation, inducing an ascending volley. The antidromic ascending motor component stops at the anterior horn cell level, whereas the orthodromic sensory component reaches the dorsal columns. The 15-ms interstimulus interval between peripheral conditioning and spinal test stimulation makes the collision with descending volleys occur in the spinal cord. The descending sensory volley is blocked, whereas the descending motor volley is unaffected. RESULTS: Reproducible evoked potentials were recorded from the tibial nerve in all the patients studied when the conditioning stimulation was performed. These conditioned neurogenic mixed evoked potentials consist of a small and polyphasic wave whose amplitude represents approximately 26% that of the wave of unconditioned neurogenic mixed evoked potentials. It is likely that they correspond to motor spinal pathway activation. CONCLUSION: Both standard and conditioned neurogenic mixed evoked potentials are proposed to provide combined sensory and motor spinal pathway monitoring.

Paradoxical air embolism from patent foramen ovale in scoliosis surgery.

STUDY DESIGN: A case was reported in which paradoxical air embolism arose from the patent foramen ovale in scoliosis surgery. OBJECTIVES: To present a case of suspected paradoxical air embolism after scoliosis surgery. SUMMARY OF BACKGROUND DATA: Embolic accident during scoliosis surgery may be caused by air, thrombus, or fat. There is growing attention on patent foramen ovale involved in paradoxical embolism. The devastating consequences are caused by multiple artery occlusions. METHODS: Details of a recent documented neurologic complication (paraplegia, weakness of right arm, and blurry vision) after scoliosis surgery have been analyzed in medical publications. RESULTS: The surgical procedure was not imputed. The causative role of epidural catheter for analgesia was considered, but it is likely that a paradoxical embolism occurred in this case, based on the multifocal (cerebral and spinal) neurologic dysfunction, the evidence of cerebral ischemia (on computed tomography), and the presence of a patent foramen ovale (on postoperative transesophageal echocardiography). Although no intraoperative embolism detection was available, air embolism was highly suspected because there was no absolute argument to exclude cruor or fatty embolism. CONCLUSIONS: It is critical to detect a patent foramen ovale before surgery and cerebral embolization intraoperatively. This might permit ascertainment of the etiologic diagnosis in case of a complication in surgery for scoliosis.