Spontaneous induced bone fusion in minimally invasive fusionless bipolar fixation in neuromuscular scoliosis: a computed tomography analysis.

PURPOSE: Posterior spinal fusion (PSF) at skeletal maturity is still the gold standard in children with neuromuscular scoliosis (NMS) who underwent fusionless surgery. The aim of this computed tomography (CT) study was to quantify the spontaneous bone fusion at the end of a lengthening program by minimally invasive fusionless bipolar fixation (MIFBF), that could avoid PSF. METHODS: NMS operated on with MIFBF from T1 to the pelvis and at final lengthening program were included. CT was performed at least five years postoperatively. The autofusion was classified as completely or not fused at the facets joint (on both coronal and sagittal plane, right and left side, from T1 to L5), and around the rods (axial plane, right and left side, from T5 to L5). Vertebral body heights were assessed. RESULTS: Ten patients were included (10.7y ± 2 at initial surgery). Mean Cobb angle was 82 ± 20 preoperatively and 37 ± 13 at last follow-up. CT were performed on average 6.7y ± 1.7 after initial surgery. Mean preoperative and last follow-up thoracic vertebrae height were respectively 13.5 mm ± 1.7 and 17.4 mm ± 1.7 (p < 0.001). 93% facets joints were fused (out of 320 analyzed joints), corresponding to 15/16 vertebral levels. Ossification around the rods was observed in 6.5±2.4 levels out of 13 in the convex side, and 4.2 ± 2.2 in the concave side (p = 0.04). CONCLUSIONS: This first computed quantitative study showed MIFBF in NMS preserved spinal growth, while it induced 93% of facet joints fusion. This could be is an additional argument when questionning the real need for PSF at skeletal maturity.

3D quasi-automatic spine length assessment using low dose biplanar radiography after surgical correction in thoracic idiopathic scoliosis.

OBJECTIVE: Surgical correction of thoracic scoliosis leads to a height improvement. Our objectives were to assess how the linear and developed spinal column lengths relate to the frontal and sagittal parameters after a surgical correction of thoracic idiopathic scoliosis, and whether the measurement of these lengths is reliable using quasi-automatic 3D reconstruction methods with biplanar X-rays. METHODS: Consecutive children with thoracic idiopathic scoliosis who underwent spinal fusion surgery and biplanar pre and postoperative X-rays in free-standing position were included prospectively. Quasi-automatic computed 3D reconstructions of the spine were done using a previously validated technique and allowed the automatic computation of geometrical spinopelvic parameters including OD-pelvis, linear, and developed T1-T12 and T1-L5 lengths. RESULTS: Thirty patients with scoliosis were included, and 240 reconstructions were performed (2 operators x2 repetitions x30 patients pre and postoperative). The main thoracic Cobb angle, T1-T12, T1-L5 linear and developed distance, OD-pelvis were significantly improved (p < 0.001). The gain of the main thoracic Cobb angle (31.6°;SD = 9°) was correlated to the gain of the linear distance T1-T12 (15.3 mm;SD=7.3 mm)(rho = 0.76;p < 0.0001) and T1-L5 (24.7 mm;SD = 8 mm)(rho = 0.64;p < 0.0001). The postoperative change of developed length between T1-L5 represented 41% of the gain in linear distance between the same vertebrae. Similarly, the gain of T1-T12 developed length was 50% of linear T1-T12 height gain. Both differences were significant (p = 0.01). Absolute bias using Bland & Altman plots was lower than 1 mm for linear distance (0.1%) and lower than 2 mm (0.3%) for developed distance. CONCLUSION: The gain in spinal length is correlated to the thoracic Cobb angle correction in the surgical treatment of idiopathic thoracic scoliosis. The new significant finding is that the developed spinal height gain represented approximately a little less than 50% of the linear spinal height gain and these parameters were reliable from a 3D quasi-automatic reconstruction of biplanar X-ray.

Micro-mechanical damage of needle puncture on bovine annulus fibrosus fibrils studied using polarization-resolved Second Harmonic Generation(P-SHG) microscopy.

Needle injection has been widely used in spinal therapeutic or diagnostic processes, such as discography. The use of needles has been suspected in causing mild disc degeneration which can lead to long-term back pain. However, the localised microscopic damage caused by needles has not been well studied. The local progressive damage on a microscopic level caused by needle punctures on the surface of bovine annulus fibrosus was investigated. Four different sizes of needle were used for the puncture and twenty-nine bovine intervertebral discs were studied. Polarization-resolved second harmonic generation and fluorescent microscopy were used to study the local microscopic structural changes in collagen and cell nuclei due to needle damage. Repeated 70 cyclic loadings at ±5% of axial strain were applied after the needle puncture in order to assess progressive damage caused by the needle. Puncture damage on annulus fibrosus were observed either collagen fibre bundles being pushed aside, being cut through or combination of both with part being lift or pushed in. The progressive damage was found less relevant to the needle size and more progressive damage was only observed using the larger needle. Two distinct populations of collagen, in which one was relatively more organised than the other population, were observed especially after the puncture from skewed distribution of polarization-SHG analysis. Cell shape was found rounder near the puncture site where collagen fibres were damaged.

Biomechanical cadaver study of proximal fixation in a minimally invasive bipolar construct.

STUDY DESIGN: Biomechanical human cadaver study. OBJECTIVE: To determine the three-dimensional intervertebral ranges of motion (ROMs) of intact and hook-instrumented thoracic spine specimens subjected to physiological loads, using an in vitro experimental protocol with EOS biplane radiography. Pedicle screws are commonly used in thoracic instrumentation constructs, and their biomechanical properties have been widely studied. Promising clinical results have been reported using a T1-T5 thoracic hook-claw construct for proximal rod anchoring. Instrumentation stability is a crucial factor in minimizing mechanical complications rates but had not been assessed for this construct in a biomechanical study. METHODS: Six fresh-frozen human cadaver C6-T7 thoracic spines were studied. The first thoracic vertebrae were instrumented using two claws of supra-laminar and pedicle hooks, each fixed on two adjacent vertebrae, on either side of a single free vertebra. Quasi-static pure-moment loads up to 5 Nm were applied to each specimen before and after instrumentation, in flexion-extension, right and left bending, and axial rotation. Five steel beads impacted in each vertebra allowed 3D tracking of vertebral movements on EOS biplanar radiographs acquired after each loading step. The relative ranges of motion (ROMs) of each pair of vertebras were computed. RESULTS: Mean ROMs with the intact specimens were 17° in flexion-extension, 27.9° in lateral bending, and 29.5° in axial rotation. Corresponding values with the instrumented specimens were 0.9°, 2.6°, and 7.3°, respectively. Instrumentation significantly (P < 0.05) decreased flexion-extension (by 92-98%), lateral bending (by 87-96%), and axial rotation (by 68-84%). CONCLUSION: This study establishes the biomechanical stability of a double claw-hook construct in the upper thoracic spine, which may well explain the low mechanical complication rate in previous clinical studies. LEVEL OF EVIDENCE: Not applicable, experimental cadaver study.

Biplanar stereoradiography predicts pulmonary function tests in adolescent idiopathic scoliosis: a cross-sectional study.

PURPOSE: Various spinal and rib cage parameters measured from complex examinations were found to be correlated with preoperative pulmonary function tests (PFT). The aim was to investigate the relationship between preoperative rib cage parameters and PFT using biplanar stereoradiography in patients with severe adolescent idiopathic scoliosis. METHODS: Fifty-four patients, 45 girls and nine boys, aged 13.8 ± 1.2 years, with Lenke 1 or 2 thoracic scoliosis (> 50°) requiring surgical correction were prospectively included. All patients underwent preoperative PFT and low-dose biplanar X-rays. The following data were collected: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio, residual volume, slow vital capacity (SVC), total lung capacity (TLC), rib cage volume (RCV), maximum rib hump, maximum width, mean thoracic index, spinal penetration index, apical vertebral rotation, main curve Cobb angle (MCCA), T4-T12 kyphosis. The primary outcome was the relationship between rib cage parameters and PFT. The secondary outcome was the relationship between rib cage parameters and spine parameters. Data were analyzed using Spearman's rank test. A multivariable regression analysis was performed to compare PFTs and structural parameters. Significance was set at α = 0.05. RESULTS: The mean MCCA was 68.7° ± 16.7°. RCV was highly correlated with all pulmonary capacities: TLC (r = 0.76, p < 0.0001), SVC (r = 0.78, p < 0.0001) and FVC (r = 0.77, p < 0.0001). RCV had a low correlation with FEV1/FVC (r = - 0.34, p = 0.014). SPI was not correlated with any pulmonary parameters. CONCLUSION: Rib cage volume measured by biplanar stereoradiography may represent a prediction tool for PFTs. LEVEL OF EVIDENCE: Non-randomized cross-sectional study among consecutive patients, Level 2. These slides can be retrieved under Electronic Supplementary Material.

Feasibility of sub-dermal soft tissue deformation assessment using B-mode ultrasound for pressure ulcer prevention.

Pressure Ulcer (PU) prevention remains a main public health issue. The physio-pathology of this injury is not fully understood, and a satisfactory therapy is currently not available. Recently, several works suggested that mechanical strains are responsible of deformation-induced damage involved in the initiation of Deep Tissue Injury (DTI). A better assessment of the internal behavior could allow to enhance the modeling of the transmission of loads into the different structures composing the buttock. A few studies focused on the experimental in vivo buttock deformation quantification using Magnetic Resonance Imaging (MRI), but its use has important drawbacks. In clinical practice, ultrasound imaging is an accessible, low cost, and real-time technic to study the soft tissue. The objective of the present work was to show the feasibility of using B-mode ultrasound imaging for the quantification of localised soft-tissue strains of buttock tissues during sitting. An original protocol was designed, and the intra-operator reliability of the method was assessed. Digital Image Correlation was used to compute the displacement field of the soft tissue of the buttock during a full realistic loading while sitting. Reference data of the strains in the frontal and sagittal planes under the ischium were reported for a population of 7 healthy subjects. The average of shear strains over the region of interest in the fat layer reached levels up to 117% higher than the damage thresholds previously quantified for the muscular tissue in rats. In addition, the observation of the muscles displacements seems to confirm previous results which already reported the absence of muscular tissue under the ischium in the seated position, questioning the assumption commonly made in Finite Element modeling that deep tissue injury initiates in the muscle underlying the bone.

The hierarchical response of human corneal collagen to load.

Fibrillar collagen in the human cornea is integral to its function as a transparent lens of precise curvature, and its arrangement is now well-characterised in the literature. While there has been considerable effort to incorporate fibrillar architecture into mechanical models of the cornea, the mechanical response of corneal collagen to small applied loads is not well understood. In this study the fibrillar and molecular response to tensile load was quantified using small and wide angle X-ray scattering (SAXS/WAXS), and digital image correlation (DIC) photography was used to calculate the local strain field that gave rise to the hierarchical changes. A molecular scattering model was used to calculate the tropocollagen tilt relative to the fibril axis and changes associated with applied strain. Changes were measured in the D-period, molecular tilt and the orientation and spacing of the fibrillar and molecular networks. These measurements were summarised into hierarchical deformation mechanisms, which were found to contribute at varying strains. The change in molecular tilt is indicative of a sub-fibrillar "spring-like" deformation mechanism, which was found to account for most of the applied strain under physiological and near-physiological loads. This deformation mechanism may play an important functional role in tissues rich in fibrils of high helical tilt, such as skin and cartilage. STATEMENT OF SIGNIFICANCE: Collagen is the primary mediator of soft tissue biomechanics, and variations in its hierarchical structure convey the varying amounts of structural support necessary for organs to function normally. Here we have examined the structural response of corneal collagen to tensile load using X-rays to probe hierarchies ranging from molecular to fibrillar. We found a previously unreported deformation mechanism whereby molecules, which are helically arranged relative to the axis of their fibril, change in tilt akin to the manner in which a spring stretches. This "spring-like" mechanism accounts for a significant portion of the applied deformation at low strains (<3%). These findings will inform the future design of collagen-based artificial corneas being developed to address world-wide shortages of corneal donor tissue.

Comparison of superficial digital flexor tendon loading on asphalt and sand in horses at the walk and trot.

The incidence of superficial digital flexor tendon (SDFT) injuries is one of the highest of all equine musculoskeletal conditions. Horses with SDFT injuries commonly show no improvement of lameness on soft ground, unlike those suffering from distal bone or joint lesions. The aim of this study was to compare the SDFT loading in five horses at the walk and trot on asphalt and sand using a non-invasive ultrasonic tendon force measurement device. Three horses were equipped with the ultrasonic device, whereas the other two horses were equipped with the ultrasonic device and a dynamometric horseshoe (DHS); the DHS was used to calibrate the measured values of tendon speed of sound (SOS) converted to tendon force, while a previously established ground reaction force pattern was used to calibrate SOS measurements for the other three horses. Although the horses tended to be slower on S, maximal tendon force was higher on sand than on asphalt at the trot (+6%); there was no significant difference between the two surfaces at the walk. The duration of tendon loading was longer on S (+5%) and the area under the tendon force-time curve was larger on S (+10%) at both walk and trot. SDFT loading is significantly affected by the ground surface and the observed increase in SDFT loading on sand compared with asphalt is consistent with clinical observations in horses with SDFT injuries.

Comparative kinematic analysis of the leading and trailing forelimbs of horses cantering on a turf and a synthetic surface.

REASONS FOR PERFORMING STUDY: The relationship between track surface properties and limb kinematics is poorly understood. Hoof orientation within the track surface has never been quantified under training conditions. Previously described kinematic and dynamic differences between leading and trailing forelimbs at the canter poorly correlate with epidemiological data regarding injuries. OBJECTIVES: To compare joint kinematics and hoof orientation in the leading and trailing forelimbs of horses cantering on turf and on a synthetic surface. STUDY DESIGN: Noninvasive experimental study. METHODS: The right forelimb of 5 horses was equipped with markers facing the main joints while markers and a dynamometric horseshoe were placed on the hoof. The horses were filmed with 2 high-speed cameras (1000 Hz) while cantering (30 km/h). Recordings were repeated at each lead and alternated on turf and on a synthetic surface. Joint angles and angles of the hoof and limb to the track were measured from the 2-dimensional coordinates of the markers. RESULTS: Elbow, carpus and fetlock were more maximally flexed during swing and had a larger range of motion throughout the stride in the leading forelimb. Maximal carpal extension during stance was also larger on this limb, which had a more toe-up orientation. Comparing surfaces, the limb was more oblique at landing, the range of motion of the hoof into the surface was larger, most kinematic events were delayed and fetlock and carpus extension velocities were smaller on the synthetic surface. CONCLUSIONS: The differences between limbs were more prominent than those between surfaces and the more toe-up orientation on the hoof of the leading forelimb suggests a different loading of that limb's joints and tendons. Differences between limbs may be important in the interpretation of lead changes in lame horses. While the synthetic surface appears to be less strenuous for the joints in the forelimbs, it was associated with changes in timing of the kinematic events of the stride.

A randomized clinical trial comparing radiation therapy v radiation therapy plus cis-dichlorodiammine platinum (II) in the treatment of locally advanced non-small cell lung cancer.

Cis-Dichlorodiammine platinum (II) (cis-DDP) was demonstrated to be a potentiator of radiation therapy (RT) in experimental tumor models and in cultured cells. To assess the effectiveness of a combined modality treatment including RT and a weekly low-dose administration of cis-DDP, from January 1986 to June 1987, 95 patients with unresectable locally advanced non-small cell carcinoma of the lung (stage IIIa, b) were randomized for study. Fifty patients received RT alone at doses of 50 Gy; 45 patients received the same RT plus cis-DDP 15 mg/m2 IV weekly. An overall response rate of 50% and 64% was observed in the RT and RT + cis-DDP group, respectively. No statistically significant differences were detected with regard to median survival time (11 months for RT v 16 months for RT + cis-DDP) and progression-free interval (7 months in the RT arm v 9 months in the RT + cis-DDP arm), but the patterns of the first failure appeared to be affected by treatment. In fact, a lower number of intrathoracic relapses was observed in the RT + cis-DDP arm (12 in the RT + cis-DDP v 23 in the RT arm). Toxicity was mild and the feasibility of this schedule must be remarked. A better local control of disease can be obtained using cis-DDP as a radiation potentiator, but the true influence of this combined modality treatment on the length of survival, and the optimal cis-DDP timing and dosage are still to be evaluated in further clinical trials.