Porous titanium-nickel for intervertebral fusion in a sheep model: part 2. Surface analysis and nickel release assessment.

Porous titanium-nickel (PTN) devices represent an alternative to traditional cage implants. PTN materials possess an interconnecting network of pores with capillarity properties that may promote bone ingrowth, long-term fixation, and intervertebral fusion without the need for bone grafting. However, their considerable surface area and nickel content may elicit concerns over sensitization potential. Therefore, PTN surface corrosion and nickel release resistance must be carefully studied. To evaluate this possibility, a PTN interbody fusion device (IFD) was compared to a conventional nonporous cage made of TiAlV, a well-known biocompatible biomaterial, in a sheep model. PTN and TiAlV IFDs were inserted at two non-contiguous lumbar sites for 3, 6, and 12 months postsurgery. Their surface was then evaluated by scanning electron microscopy (SEM) combined with backscattered electron analysis (BSE). No evidence of surface corrosion was observed either pre- or postimplantation, regardless of device type. Dosage of nickel ions was also performed with the use of inductively coupled plasma-mass spectrometry (ICP-MS). Blood nickel levels were observed to be within acceptable levels at all postinstrumentation times. Nickel content in PTN-adjacent tissue, as well as in detoxification and remote organs, was equivalent both in PTN-treated and control sheep. Therefore, porous titanium-nickel demonstrated resistance to both in vivo surface corrosion and nickel ion release and compared very well with a conventional titanium implant in the course of a 12-month sheep study.

Altered mechanics and histomorphometry of canine tibial cartilage following joint immobilization.

Joint immobilization is associated with altered cartilage biosynthesis and catabolism that may affect cartilage mechanics and joint function. In this study, the mechanical behavior of articular cartilage was studied in an experimental model of joint immobilization, in which the canine knee was cast-immobilized at 90 degrees of flexion for 4 weeks. Articular cartilage from the medial tibial plateau was tested in compression and in shear. Biochemical assays for water and glycosaminoglycan content and histomorphometric grading were performed on site-matched samples. Significant decreases in the equilibrium and dynamic shear moduli, but not compressive moduli, were observed in cartilage after 4 weeks of joint immobilization as compared to cartilage from a separate control population. Importantly, there was also evidence of a decrease in the compressive and shear moduli of tibial cartilage from the contralateral knee joints compared to control joints that were not immobilized. No significant effect of immobilization on the biochemical parameters or histomorphometric scores was detected, expect for a significant loss of proteoglycan staining following immobilization. These findings for changes in the tibial cartilage following cast immobilization are consistent with a mild form of cartilage degeneration.

Acute postural adaptations induced by a shoe lift in idiopathic scoliosis patients.

The objective of this study was to identify acute spinal and three-dimensional postural adaptations induced by a shoe lift in a population of idiopathic scoliosis (IS) patients. Forty-six IS patients (mean age: 12 +/- 2 years) were evaluated radiologically and with a stereovideographic system for pelvic obliquity. Based on the initial postural and radiological evaluation, a pertinent shoe lift height was chosen for each with the result that 12 patients were tested with 5-mm (S5) lifts, 20 patients were tested with 10-mm (S10) lifts, and 14 patients with 15-mm (S15) lifts. The posture for all 46 patients was then re-evaluated and a spinal radiograph obtained for 14 patients. The implementation of a shoe lift independent of the type of curve and amplitude significantly decreased the Cobb angle. As expected there was a change in the vertical height of the left tibial plateau and greater trochanter that induced a change in pelvic tilt. There was also a significant increase in the vertical height of S1 and T1. There was a significant change in the left and right iliac bone version, as well as a decrease in the difference in version between these two bones. The implementation of the shoe lifts also changed the lateral shift of the pelvis. A relative change between the shoulders and pelvis for tilt and anteroposterior shift was also found to be significant. In conclusion, using a shoe lift resulted in acute postural adaptations which specifically affected the spine and the three-dimensional position and orientation of the pelvis and shoulder girdle.

Simultaneous changes in the mechanical properties, quantitative collagen organization, and proteoglycan concentration of articular cartilage following canine meniscectomy.

The mechanical properties and microstructure of articular cartilage from the canine tibial plateau were studied 12 weeks after total medial meniscectomy. The organization of the birefringent collagen network was measured with quantitative polarized light microscopy to determine the thickness and the degree of organization of the superficial and deep zones. The zonal concentration of sulfated glycosaminoglycan was quantified with digital densitometry of safranin-O staining. Equilibrium compressive and shear properties, as well as dynamic shear properties, were measured at sites adjacent to those of microstructural analysis. The results evinced significant loss of cartilage function following meniscectomy, with decreases of 20-50% in the compressive and shear moduli. There was no evidence of alterations in the degree of collagen fibrillar organization, although a complete loss of the surface zone was seen in 60% of the samples that underwent meniscectomy. Meniscectomy resulted in a decreased concentration of sulfated glycosaminoglycan, and significant positive correlations were found between the equilibrium compressive modulus and the glycosaminoglycan content. Furthermore, the shear properties of cartilage correlated directly with collagen fibrillar organization measured at the superficial zone of corresponding sites. These findings demonstrate that meniscectomy leads to impaired mechanical function of articular cartilage, with significant evidence of quantitative correlations between cartilage microstructure and mechanics.

A noninvasive anthropometric technique for measuring kyphosis and lordosis: an application for idiopathic scoliosis.

STUDY DESIGN: Cross-sectional measurement of the sagittal geometry of adolescent idiopathic scoliosis patients. OBJECTIVES: To evaluate the accuracy of a noninvasive anthropometric approach for the measurement of kyphosis and lordosis. SUMMARY OF BACKGROUND DATA: Noninvasive approaches were developed to estimate the sagittal curvatures of the spine. However, the magnitude of the estimation error could be high for an important proportion of patients, which leads to a difficult clinical application. METHODS: The group was composed of 124 female patients with a mean age of 13.5 years (SD 2. 7 years) with Cobb angles ranging from 4 degrees to 66 degrees. Kyphosis and lordosis were measured on the lateral radiograph. The spine sagittal curvature of the same patients was also estimated using the spatial localization of skin markers placed overlying the spinous processes. These coordinates served as input into a simple trigonometric model. Data were collected by means of a stereovideographic technique (Motion Analysis Corp., Santa Rosa, CA). RESULTS: The intraclass correlation coefficient between both approaches was 0.94 for kyphosis and 0.91 for lordosis; the mean absolute differences were 5 degrees (SD 4 degrees ) and 6 degrees (SD 6 degrees ), respectively. The difference was less than 10 degrees in 91% of the patients for kyphosis, and in 79% for lordosis. CONCLUSIONS: The proposed technique appears to give more representative results than those presented in the literature. It has the advantage of being part of a global noninvasive postural evaluation. Using this approach in a systematic manner could help reduce radiograph exposure while keeping track of the spine sagittal curvatures.

Relationship between gibbosity and Cobb angle during treatment of idiopathic scoliosis with the SpineCor brace.

The objective of this study was to quantify the relationship between gibbosity and spinal deformation expressed by the angle of Cobb before and during treatment with a brace for different classes of idiopathic scoliosis patients. As part of the standard treatment with the Dynamic Corrective Brace (SpineCor), 89 idiopathic scoliosis patients underwent an initial radiological examination and gibbosity measurement with a scoliometer wearing and not wearing the brace. The 89 patients were classified in relation to the apex of the scoliosis curves: thoracic (n = 29); thoracolumbar (n = 40); lumbar (n = 7) and double (n = 13). With the dynamic corrective brace, the patients showed a mean decrease of 8.3 degrees for the major Cobb angle, and a mean decrease of 2.3 degrees for their gibbosity. There was a significant positive relationship between gibbosity and Cobb angle with and without the brace for the thoracic and thoracolumbar curves. A linear regression analysis identified a small mean estimation error for the thoracic curves (7.4 degrees no-brace; 2.7 degrees with brace) and thoracolumbar curves (5.2 degrees no-brace; 5.3 degrees with brace), indicating a predictive potential of the scoliometer. The measure of gibbosity with the scoliometer provides a fairly reliable estimation of Cobb angle at the initial clinical examination of a scoliosis patient. However, when initial Cobb angle and gibbosity are considered, the measure of gibbosity when wearing a brace provides the clinician with a highly reliable estimation of the Cobb angle while in a brace. This relationship also exists for the follow-up with a brace, permitting a judgement of the patient's evolution under the treatment with SpineCor.

[Comparison of the reliability of two 3D acquisition systems used for the study of anthropometric and postural parameters]. / Comparaison de la fidélité de deux systèmes d'acquisition 3D sur l'étude de paramètres anthropométriques et posturaux.

The goal of this study is to compare the between trials and between session reliability of the postural geometry (PG) and anthropometrical evaluations, obtained by the FreePoint (FP) system and the Motion Analysis System (MA). The potential of automatization of the anthropometric evaluation is also evaluate through the comparison of height measurements obtained by the two 3D systems and traditional anthropometrical tools. The PG of 15 adult control subjects (x: 25 years, SD: 6) evaluated on two occasions (1 week interval) and a mannequin on one occasion were evaluated with both systems. Each evaluation involved the identification of 52 anatomical landmarks followed by the acquisition of 5 trials with each system. The 3 dimensional position of the anatomical landmarks serves to define a postural model including the shoulder girdle, spinous processes (T1 to S1), thorax, pelvis, lower extremities and base of support. Postural parameters were calculated, including rotations, tilts, versions, kyphosis, lordosis, right and left Cobb, anteroposterior shifts, (AP), mediolateral shifts (ML) and vertical heights. The between trials and between session results demonstrate a strong correspondence of the 15 anthropometric heights and the 20 postural parameters between the three systems, permitting the proposal of a broadened clinical utilisation of the FreePoint system. However, the validity of these measures is influenced by the reliability of the anthropometric landmarking, natural oscillation of the body and the intra-specific variation of the posture of each subject.

[Reductibility of idiopathic scoliosis during orthopedic treatment]. / La réductibilité des scolioses idiopathiques dans le traitement orthopédique.

Non-operative treatment of idiopathic scoliosis is long and difficult. For the patient and the therapist it is particularly important to define early the therapeutic prognosis. The goal of this study is to verify if the initial reducibility at the beginning of treatment with the dynamic corrective brace (Spinecor) would be valid as a prognostic factor, allowing a more effective prognostic judgement of the final outcome treatment. This is a prospective study which includes 99 scoliosis patients (88 female, 11 male), with a mean age of new 12.6 years, treated by the dynamic corrective brace for progressive idiopathic scoliosis curves (29 degrees mean Cobb angle). The initial Cobb angle was compared to the pre-therapeutic Cobb angle. The results demonstrate that the reducibility of the scoliotic curves with the brace at the beginning of treatment provides a significant global prognostic index but is difficult to apply individually. Other factors should be considered, such as the impact of growth velocity on the spinal deformity at the onset of the adolescent growth spent as well as vertebral deformities diagnosed around the apex.

Compressive and shear properties of alginate gel: effects of sodium ions and alginate concentration.

The equilibrium and viscoelastic properties of alginate gel crosslinked with Ca2+ were determined as a function of alginate concentration and duration of exposure to physiologic concentrations of NaCl. Compressive and shear stress relaxation tests and oscillatory shear tests were performed to measure the material properties at two time periods after storage in NaCl compared to no NaCl exposure. The effect of concentration was determined by testing 1-3% alginate gel in a bath of physiological NaCl and CaCl2. After 15 h of exposure to NaCl, the compressive, equilibrium shear, and dynamic shear moduli decreased by 63, 84, and 90% of control values, respectively. The material properties exhibited no further changes after 7 days of exposure to NaCl. The loss angle and amplitude of the relaxation function in the shear also decreased, indicating less viscous behaviors in both dynamic and transient configurations. All moduli, but not the loss angle, significantly increased with increasing alginate concentration. The observed decrease in compressive and shear stiffness for alginate gel after exposure to Na+ was significant and indicated that physiological conditions will soften the gel over a time period of up to 7 days after gelation. The alginate gel retains significant solid-like behaviors, however, as measured by a loss angle of approximately 3 degrees. This study provides the first available data for material properties of alginate gel tested in physiological saline.

Acute systematic and variable postural adaptations induced by an orthopaedic shoe lift in control subjects.

A small leg length inequality, either true or functional, can be implicated in the pathogenesis of numerous spinal disorders. The correction of a leg length inequality with the goal of treating a spinal pathology is often achieved with the use of a shoe lift. Little research has focused on the impact of this correction on the three-dimensional (3D) postural organisation. The goal of this study is to quantify in control subjects the 3D postural changes to the pelvis, trunk, scapular belt and head, induced by a shoe lift. The postural geometry of 20 female subjects (X = 22, sigma = 1.2) was evaluated using a motion analysis system for three randomised conditions: control, and right and left shoe lift. Acute postural adaptations were noted for all subjects, principally manifested through the tilt of the pelvis, asymmetric version of the left and right iliac bones, and a lateral shift of the pelvis and scapular belt. The difference in the version of the right and left iliac bones was positively associated with the pelvic tilt. Postural adaptations were noted to vary between subjects for rotation and postero-anterior shift of the pelvis and scapular belt. No notable differences between conditions were noted in the estimation of kyphosis and lordosis. The observed systematic and variable postural adaptations noted in the presence of a shoe lift reflects the unique constraints of the musculoskeletal system. This suggests that the global impact of a shoe lift on a patient's posture should also be considered during treatment. This study provides a basis for comparison of future research involving pathological populations.

[Classification of left thoracolumbar scoliosis according to its radiologic morphology and its postural geometry]. / Classification des scolioses thoraco-lombaires gauches selon leur morphologie radiologique et leur géométrie posturale.

Idiopathic scoliosis is a tridimensional (3D) deformation of the spine associated with postural geometry (PG) disorganisation. Conventional classification of scoliosis is primarily based on the analysis of PA X-rays. This is a descriptive classification that forms heterogeneous groups. Diagnosis, prognosis and treatments are then developed around partial information. The goal of this project was to divide the left thoracolumbar (TLG) class in two subgroups using exhaustive analysis of the PA and lateral X-rays, and the evaluation of postural deformations. The quantification of the PG of 14 control subjects and 20 scoliotic patients (TLG) was realised using a stereovideographic approach. For each patient, PA and lateral X-rays were done using a digital X-ray apparatus. The TLG group shows common pathological characteristics but is forming a relatively heterogeneous group. When this class is divided in two subgroups, 9 postural parameters appeared to be different from the control group, each subgroup showing specific postural characteristics. The 3D quantification of pertinent radiological parameters and the PG evaluation should allow the classification of idiopathic scoliosis patients. Furthermore, these groups of patients could be characterised, in order to improve the diagnosis, the prognosis and the treatment, with a brace or surgically.

[Stereovideographic evaluation of the postural geometry of healthy and scoliotic patients]. / Evaluation stéréovidéographique de la géométrie posturale du sujet sain et scoliotique.

Idiopathic scoliosis principally characterised by a deformation of the vertebral column can also be associated to postural abnormalities. The validity and reliability of current quantitative postural evaluations has not been thoroughly documented, frequently limited by a two dimensional view of the patient, and do not include the whole posture of the patient. The purpose of this study is to 1) quantify within and between-session reliability of a stereovideographic Postural Geometry (PG) evaluation and 2) to investigate the sensitivity of this technique for the postural evaluation of scoliosis patients. The PG of 14 control subjects and 9 untreated scoliosis patients were evaluated with 5 repeat trials, on two occasions. Postural geometry parameters that describe the position and orientation of the pelvis, trunk, scapular girdle and head were calculated based on the 3-dimensional co-ordinates of anatomical landmarks. The mean between and within-session variability across all parameters were 12.5 mm, 2.8 degrees and 5.4 mm and 1.4 degrees respectively. The patient group was heterogeneous with some noted pathological characteristics. This global stereovideographic postural geometry evaluation appears to demonstrate sufficient reliability and sensitivity to follow-up on the posture of scoliosis patients.

Capilaroscopia en Raynaud primario y secundario / Capillaroscopy in primary and secondary Raynaud

Se estudian 32 pacientes y un grupo control de 10 personas con un protocolo que consta de : Cínica, inmunología y capilaroscopía. Esta última es una técnica de visualización in vivo de los capilares del lecho ungueal a traveés de una lupa estereos-cópica. Se analiza edad de aparición, correlación de los tres items del protocolo y enfermedad de base en Raynaud secundario. Los pacientes se dividieron en: Raynaud primario (7), Raynaud secundario (19) y Raynaud indeterminado (4). La sensibilidad del presente estudio para el diagnóstico diferencial fue del 81,3 por ciento. Además se analiza la alteración de la morfologá capilar y la injuria capilar (presencia de hemorragias) a nivel capilaroscópico

Capilaroscopia en Raynaud primario y secundario / Capillaroscopy in primary and secondary Raynaud

Se estudian 32 pacientes y un grupo control de 10 personas con un protocolo que consta de : Cínica, inmunología y capilaroscopía. Esta última es una técnica de visualización in vivo de los capilares del lecho ungueal a traveés de una lupa estereos-cópica. Se analiza edad de aparición, correlación de los tres items del protocolo y enfermedad de base en Raynaud secundario. Los pacientes se dividieron en: Raynaud primario (7), Raynaud secundario (19) y Raynaud indeterminado (4). La sensibilidad del presente estudio para el diagnóstico diferencial fue del 81,3 por ciento. Además se analiza la alteración de la morfologá capilar y la injuria capilar (presencia de hemorragias) a nivel capilaroscópico(AU)