Neurophysiological changes during shortening osteotomies of the spine.

BACKGROUND CONTEXT: Kyphotic deformities with sagittal imbalance of the spine can be treated with spinal osteotomies. Those procedures are known to have a high incidence of neurological complications, in particular at the thoracic level. Motor evoked potentials (MEPs) have been widely used in helping to avoid major neurological deficits postoperatively. Previous reports have shown that a significant proportion of such cases present with important transcranial MEP (Tc-MEP) changes during surgery with some of them being predictive of postoperative deficits. PURPOSE: Our aim was to study Tc-MEP changes in a consecutive series of patients and correlate them with clinical parameters and radiological changes. STUDY DESIGN/SETTING: Retrospective case notes study from a prospective patient register. PATIENT SAMPLE: Eighteen patients undergoing posterior shortening osteotomies (nine at thoracic and nine at lumbar levels) for kyphosis of congenital, degenerative, inflammatory, or post-traumatic origin were included. OUTCOME MEASURES: Loss of at least 80% of Tc-MEP signal expressed as the area under the curve percentual change, of at least one muscle. METHODS: We studied the relation between outcome measure (80% Tc-MEP loss in at least one muscle group) and amount of posterior vertebral body shortening as well as angular correction measured on computed tomography scans, occurrence of postoperative deficits, intraoperative blood pressure at the time of the osteotomy, and hemoglobin (Hb) change. RESULTS: All patients showed significant Tc-MEP changes. In particular, greater than 80% MEP loss in at least one muscle group was observed in five of nine patients in the thoracic group and four of nine patients in the lumbar group. No surgical maneuver was undertaken as a result of this loss in an effort to improve motor responses other than verifying the stability of the construct and the extent of the decompression. Four patients developed postoperative deficits of radicular origin, three of them recovering fully at 3 months. No relation was found between intraoperative blood pressure, Hb changes, and Tc-MEP changes. Severity of Tc-MEP loss did not correlate with postoperative deficits. Shortening of more than 10 mm was linked to more severe Tc-MEP changes in the thoracic group. CONCLUSIONS: Transcranial MEP changes during spinal shortening procedures are common and do not appear to predict severe postoperative deficits. Total loss of Tc-MEP (not witnessed in our series) might require a more drastic approach with possible reversal of the correction and wake-up test.

Cardiac raptor deletion impairs adaptive hypertrophy, alters metabolic gene expression and causes heart failure in mice

Background: Mammalian target of rapamycin (mTOR), a central regulator of cell growth, is found in two structurally and functionally distinct multiprotein complexes called mTOR complex (mTORC)1 and mTORC2. The specific roles of each of these branches of mTOR signaling have not been dissected in the adult heart. In the present study, we aimed to bring new insights into the function of cardiac mTORC1-mediated signaling in physiological as well as pathological situations.Methods: We generated mice homozygous for loxP-flanked raptor and positive for the tamoxifen-inducible Cre recombinase (MerCreMer) under control of the α- myosin heavy chain promoter. The raptor gene encodes an essential component of mTORC1. Gene ablation was induced at the age of 10-12 weeks, and two weeks later the raptor cardiac-knockout (raptor-cKO) mice started voluntary cagewheel exercise or were subjected to transverse aortic constriction (TAC) to induce pressure overload.Results: In sedentary raptor-cKO mice, ejection fractions gradually decreased, resulting in significantly reduced values at 38 days (P < 0.001). Raptor-cKO mice started to die during the fifth week after the last tamoxifen injection. At that time, the mortality rate was 36% in sedentary (n = 11) and 64% in exercising (n = 14) mice. TAC-induced pressure overload resulted in severe cardiac dysfunction already at earlier timepoints. Thus, at 7-9 days after surgery, ejection fraction and fractional shortening values were 22.3% vs 43.5% and 10.2% vs 21.5% in raptor-cKO vs wild-type mice, respectively. This was accompanied by significant reductions of ventricular wall and septal thickness as well as an increase in left ventricular internal diameter. Moreover, ventricular weight to tibial length ratios were increased in wild-type, but not in the raptor-cKO TAC mice. Together, this shows that raptor-cKO mice rapidly developed dilated cardiomyopathy without going through a phase of adaptive hypertrophy. Expression of ANP and β-MHC was induced in all raptor-cKO mice irrespective of the cardiac load conditions. Consistent with reduced mTORC1 activity, phosphorylation of ribosomal S6 kinase and 4E-BP1 was blunted, indicating reduced protein synthesis. Moreover, expression of multiple genes involved in the regulation of energy metabolism was altered, and followed by a shift from fatty acid to glucose oxidation.Conclusion: Our study suggests that mTORC1 coordinates protein and energy metabolic pathways in the heart. Moreover, we demonstrate that raptor is essential for the cardiac adaptation to increased workload and importantly, also for normal physiological cardiac function.

Application of ultrasound in bone surgery: two case reports

The present study describes some of the applications of ultrasound in bone surgery, based on the presentation of two clinical cases. The Piezosurgery® ultrasound device was used (Tecnología Mectron Medical, Carasco, Italy). In one case the instrument was used to harvest a chin bone graft for placement in a bone defect at level 1.2, while in the other case a bony window osteotomy was made in the external wall of the maxillary sinus, in the context of a sinus membrane lift procedure. The Piezosurgery® device produces specific ultrasound frequency modulation (25-29 kHz), and has been designed to secure increased precision in application to bone surgery. This instrument produces selective sectioning of the mineralized bone structures, and causes less intra- and postoperative bleeding. One of the advantages of the Piezosurgery® device is that it can be used for maxillary sinus lift procedures in dental implant placement. In this context it considerably lessens the risk of sinus mucosa laceration by preparing the bony window in the external wall of the upper maxilla, and can be used to complete the lifting maneuver. The use of ultrasound in application to hard tissues can be regarded as a slow technique compared with the conventional rotary instruments, since it requires special surgical skill and involves a certain learning curve.

Revisiting spatial distribution and biochemical composition of calcium-containing crystals in human osteoarthritic articular cartilage.

INTRODUCTION: Calcium-containing (CaC) crystals, including basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP), are associated with destructive forms of osteoarthritis (OA). We assessed their distribution and biochemical and morphologic features in human knee OA cartilage. METHODS: We prospectively included 20 patients who underwent total knee replacement (TKR) for primary OA. CaC crystal characterization and identification involved Fourier-transform infra-red spectrometry and scanning electron microscopy of 8 to 10 cartilage zones of each knee, including medial and lateral femoral condyles and tibial plateaux and the intercondyle zone. Differential expression of genes involved in the mineralization process between cartilage with and without calcification was assessed in samples from 8 different patients by RT-PCR. Immunohistochemistry and histology studies were performed in 6 different patients. RESULTS: Mean (SEM) age and body mass index of patients at the time of TKR was 74.6 (1.7) years and 28.1 (1.6) kg/m², respectively. Preoperative X-rays showed joint calcifications (chondrocalcinosis) in 4 cases only. The medial femoro-tibial compartment was the most severely affected in all cases, and mean (SEM) Kellgren-Lawrence score was 3.8 (0.1). All 20 OA cartilages showed CaC crystals. The mineral content represented 7.7% (8.1%) of the cartilage weight. All patients showed BCP crystals, which were associated with CPP crystals for 8 joints. CaC crystals were present in all knee joint compartments and in a mean of 4.6 (1.7) of the 8 studied areas. Crystal content was similar between superficial and deep layers and between medial and femoral compartments. BCP samples showed spherical structures, typical of biological apatite, and CPP samples showed rod-shaped or cubic structures. The expression of several genes involved in mineralization, including human homolog of progressive ankylosis, plasma-cell-membrane glycoprotein 1 and tissue-nonspecific alkaline phosphatase, was upregulated in OA chondrocytes isolated from CaC crystal-containing cartilages. CONCLUSIONS: CaC crystal deposition is a widespread phenomenon in human OA articular cartilage involving the entire knee cartilage including macroscopically normal and less weight-bearing zones. Cartilage calcification is associated with altered expression of genes involved in the mineralisation process.

Type I osteogenesis imperfecta and multiple osteochondromas in the same child.

A male infant showed a humeral diaphysis fracture at 5 months of age and a distal tibial physis fracture at 2 years of age. A specialized consultant ruled out child abuse. This child had the characteristic features of type I osteogenesis imperfecta: blue sclerae, osseous fragility, and presumably autosomal dominant inheritance, as his father suffered from similar disorders. Later on, multiple painful osteochondromas were also found and some of these were surgically treated. The child's mother showed several peripheral osteochondromas. We describe the follow-up of this patient up to the age of 18 years. To our knowledge, the fortuitous association of these two inherited conditions has not been reported in medical literature.

Palliative surgical procedures to restore shoulder function in obstetric brachial palsy. Critical analysis of Narakas' series.

Dr. Narakas intended to study a series of 61 cases of shoulder sequelae of obstetric palsy. His vast experience would have enriched our clinical knowledge of this ailment. The authors carry on with that study to clarify his therapeutic approach and share the benefit of his experience.

Distraction osteogenesis in the management of severe maxillary hypoplasia in cleft lip and palate patients.

The aim of this study was to systematically review literature reporting on the use of external distraction osteogenesis (DO) and internal DO in the treatment of severe maxillary hypoplasia in cleft and palate patients. Literature research has been performed using the PubMed database of the National Library of Medicine and National Institutes of Health from 1966 to August 2007. We used cleft lip and palate and distraction osteogenesis as key words. Of the 104 articles found, we only considered the Anglo-Saxon literature, which reported on the correction of the maxillary hypoplasia with DO techniques. A total of 32 studies reported on anteroposterior external DO (27 studies on rigid external device and 5 on face mask), 17 studies reported on anteroposterior internal DO, and 3 studies reported on transverse internal DO have been retained for this review. Despite the heterogeneity and methodological limitations of most of the studies, results showed that external DO with rigid external device and internal DO resulted to be a more reliable and accurate technique than the face mask in the management of severe maxillary hypoplasia in patients with cleft lip and palate. The current review demonstrated that external and internal DO in the treatment of severe maxillary hypoplasia in cleft and palate patients (1) is a reproducible and valuable alternative to standard orthognathic surgery procedures, (2) allows for a global improvement in facial aesthetic, (3) allows a maxillary correction in patients during the period of mixed dentition, and (4) allows either for an unchanged or better velopharyngeal function.

Soft tissue artifact assessment during treadmill walking in subjects with total knee arthroplasty.

Accurate measurement of knee kinematics during functional activities suffers mainly from soft tissue artifact (STA): the combination of local surface deformations and rigid movement of markers relative to the underlying bone (also called rigid STA movement: RSTAM). This study proposes to assess RSTAM on the thigh, shank, and knee joint and to observe possible features between subjects. Nineteen subjects with knee arthroplasty were asked to walk on a treadmill while a biplane fluoroscopic system (X-rays) and a stereophotogrammetric system (skin markers) recorded their knee movement. The RSTAM was defined as the rigid movement of the cluster of skin markers relative to the prosthesis. The results showed that RSTAM amplitude represents approximately 80-100% of the STA. The vertical axis of the anatomical frame of the femur was influenced the most by RSTAM. Combined with tibial error, internal/external rotation angle and distraction-compression were the knee kinematics parameters most affected by RSTAM during the gait cycle, with average rms values of 3.8° and 11.1 mm. This study highlighted higher RSTAM during the swing phase particularly in the thigh segment and suggests new features for RSTAM such as the particular shape of some RSTAM waveforms and the absence of RSTAM in certain kinematics during the gait phases. The comparison of coefficient of multiple correlations showed some similarities of RSTAM between subjects, while some correlations were found with gait speed and BMI. These new insights could potentially allow the development of new methods of compensation to avoid STA.

Etude radio-clinique comparant les résultats à court terme des prothèses totales du genou implantées soit à l'aide d'une instrumentation manuelle soit à l'aide d'un système de navigation assisté par ordinateur

Résumé: La qualité de l'implantation d'une prothèse totale du genou est un facteur essentiel déterminant le résultat clinique à long terme. L'alignement postopératoire des membres inférieurs est considéré comme le facteur influençant le plus la survie à long terme d'une arthroplastie du genou. Au vu du haut degré de corrélation entre les complications post-opératoires et les malpositionnements prothétiques, les chirurgiens ont tenté de développer durant ces deux dernières décennies des instruments chirurgicaux améliorant la précision d'implantation. Depuis le début des années 90, de nouvelles instrumentations assistées par ordinateur ont été proposées. Actuellement, en chirurgie prothétique du genou, la plus utilisée de ces techniques est le système de navigation OrthoPilot® qui permet, grâce à une station de navigation et des émetteurs infrarouges, de contrôler en continu pendant l'opération, l'axe mécanique du membre inférieur et de vérifier la précision des coupes osseuses. Le but de cette étude de cohorte appareillée rétrospective est de comparer les résultats clinique et radiologiques de deux collectifs de patients (32 patients dans chaque groupe) comparables (âge, sexe, BMI, degré d'arthrose, recul postopératoire), opérés avec le même type de prothèse (prothèse à glissement tricompartimental postérieurement stabilisée), soit avec le système de navigation Orthopilot®, soit à l'aide de l'instrumentation ancillaire mécanique classique. Les résultats obtenus montrent que la technique chirurgicale supportée par le système de navigation Orthopilot® est fiable et aisément reproductible. Par rapport à l'instrumentation manuelle, l'instrumentation assistée améliore significativement la précision de pose du composant tibial dans le plan frontal. Cependant entre des mains expérimentées, la technique d'alignement mécanique classique, plus simple, reste performante (coût modique, temps opératoire plus court et sans risque de défaillance technique).

Contribution of femoral and proximal sciatic nerve branches to the sensory innervation of hindlimb digits in the rat

The present study was performed to investigate the possibility of 'aberrant' innervation of the tips of the hindlimb digits in the rat, i.e., from other sources than the femoral and the main sciatic branches (tibial, peroneal, sural). Cutaneous injections of fluorescent tracers in the digits were combined with either selective nerve transections to restrict afferent routes followed by detection of labeled neurons in dorsal root ganglia (DRGs), or by a delayed application of a second tracer to afferent nerves under study to detect double labeled neurons in DRGs. The results show that the tips of the digits were represented in DRGs L3-6. The femoral nerve afferents from digits 1 and 2 projected primarily to DRG L3 and to a smaller extent to DRG L4. A small number of neurons from primarily medial digits 1 and 2, but also from lateral digits 3-5, were found to project to DRGs L4 and L5 via a proximal branch that leaves the sciatic nerve near the sciatic notch and runs distally in the posterior part of the thigh, here called the musculocutaneous nerve of the hindlimb. We also have some evidence indicating innervation of the tips of the digits from the posterior cutaneous nerve of the thigh. Aberrant innervation such as that described here might contribute to remaining and perhaps abnormal sensibility after nerve injury and is of interest for the interpretation of results in experimental studies of collateral and regenerative sprouting after such injury

Postnatal ontogenesis of the tibia. Implications for age and sex estimation

The growth of five variables of the tibia (diaphyseal length, diaphyseal length plus distal epiphysis, condylo-malleolar length, sagittal diameter of the proximal epiphysis, maximum breadth of the distal epiphysis) were analysed using polynomial regression in order to evaluate their significance and capacity for age and sex determination during and after growth. Data were collected from 181 (90♂ and 91♀) individuals ranging from birth to 25 years of age and belonging to three documented collections from Western Europe. Results indicate that all five variables exhibit linear behaviour during growth, which can be expressed by a first-degree polynomial function. Sexual significant differences were observed from age 15 onward in the two epiphysis measurements and condylo-malleolar length, suggesting that these three variables could be useful for sex determination in individuals older than 15 years. Strong correlation coefficients were identified between the five tibial variables and age. These results indicate that any of the studied tibial measurements is likely to serve as a useful source for estimating sub-adult age in both archaeological and forensic samples.

BS-SEM evaluation of the tisular interactions between cortical bone and calcium-phosphate covered titanium implants

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes

BS-SEM evaluation of the tisular interactions between cortical bone and calcium-phosphate covered titanium implants

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes

BS-SEM evaluation of the tisular interactions between cortical bone and calcium-phosphate covered titanium implants

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes