Giuliano Barbieri

Is the Sciatic Functional Index always reliable and reproducible

The Sciatic Functional Index (SFI) is a quite useful tool for the evaluation of functional recovery of the sciatic nerve of rats in a number of experimental injuries and treatments. Although it is an objective method, it depends on the examiners ability to adequately recognize and mark the previously established footprint key points, which is an entirely subjective step, thus potentially interfering with the calculations according to the mathematical formulae proposed by different authors. Thus, an interpersonal evaluation of the reproducibility of an SFI computer-aided method was carried out here to study data variability. A severe crush injury was produced on a 5 mm-long segment of the right sciatic nerve of 20 Wistar rats (a 5000 g load directly applied for 10 min) and the SFI was measured by four different examiners (an experienced one and three newcomers) preoperatively and at weekly intervals from the 1st to the 8th postoperative week. Three measurements were made for each print and the average was calculated and used for statistical analysis. The results showed that interpersonal correlation was high (0.82) in the 3rd, 4th, 5th, 7th and 8th weeks, with an unexpected but significant (p<0.01) drop in the 6th week. There was virtually no interpersonal correlation (correlation index close to 0) on the 1st and 2nd weeks, a period during which the variability between animals and examiners (p=0.24 and 0.32, respectively) was similar, certainly due to a poor definition of the footprints. The authors conclude that the SFI method studied here is only reliable from the 3rd week on after a severe lesion of the sciatic nerve of rats.

Ultrasound Propagation Velocity and Broadband Attenuation Can Help Evaluate the Healing Process of an Experimental Fracture

Ultrasonometry seems to have a future for the evaluation of fracture healing. Ultrasound propagation velocity (USPV) significantly decreases at the same time that bone diameter decreases as healing takes place, thus approaching normal values. In this investigation, both USPV and broadband ultrasound attenuation (BUA) were measured using a model of a transverse mid‐diaphyseal osteotomy of sheep tibiae. Twenty‐one sheep were operated and divided into three groups of seven, according to the follow‐up period of 30, 60, and 90 days, respectively. The progress of healing of the osteotomy was checked with monthly conventional radiographs. The animals were killed at the end of the period of observation of each group, both operated‐upon and intact tibiae being resected and submitted to the measurement of underwater transverse and direct contact transverse and longitudinal USPV and BUA at the osteotomy site. The intact left tibia of the 21 animals was used for control, being examined on a symmetrical diaphyseal segment. USPV increased while BUA decreased with the progression of healing, with significant differences between the operated and untouched tibiae and between the periods of observation, for most of the comparisons. There was a strong negative correlation between USPV and BUA. Both USPV and BUA directly reflect and can help predict the healing of fractures, but USPV alone can be used as a fundamental parameter. Ultrasonometry may be of use in clinical application to humans provided adequate adaptations can be developed.

A Comparative Analysis between Ultrasonometry and Computer‐Aided Tomography to Evaluate Bone Healing

An ultrasonometric and computed‐tomographic study of bone healing was undertaken using a model of a transverse mid‐shaft osteotomy of sheep tibiae fixed with a semi‐flexible external fixator. Fourteen sheep were operated and divided into two groups of seven according to osteotomy type, either regular or by segmental resection. The animals were killed on the 90th postoperative day and the tibiae resected for the in vitro direct contact transverse and axial measurement of ultrasound propagation velocity (UV) followed by quantitative computer‐aided tomography (callus density and volume) through the osteotomy site. The intact left tibiae were used for control, being examined in a symmetrical diaphyseal segment. Regular osteotomies healed with a smaller and more mature callus than resection osteotomies. Axial UV was consistently and significantly higher (p ≤ 0.01) than transverse UV and both transverse and axial UV were significantly higher for the regular than for the segmental resection osteotomy. Transverse UV did not differ significantly between the intact and operated tibiae (p = 0.20 for regular osteotomy; p = 0.02 for resection osteotomy), but axial UV was significantly higher for the intact tibiae. Tomographic callus density was significantly higher for the regular than for the resection osteotomy and higher than both for the intact tibiae, presenting a strong positive correlation with UV. Callus volume presented an opposite behavior, with a negative correlation with UV. We conclude that UV is at least as precise as quantitative tomography for providing information about the healing state of both regular and resection osteotomy.

Uma nova pinça regulável para a produção de lesões por esmagamento do nervo ciático do rato

Objective: A new adjustable pinch has been developed for producing a crush injury, with a previously known load of 5 kg, on a 5 mm-long segment of the nerve. Methods: Stainless steel was the material selected for building the pinch due its durability and possibility of sterilization with anti-septic substances, which are often corrosive. The crushing load of the pinch is adjustable by increasing or decreasing the tension of the spring by means of a screw used for calibration, which is performed by a load cell. Result: This pinch has been used in a few experimental investigations and was shown to be as efficient as both the universal testing machine and the dead weight machine, previously used. Conclusion: The developed pinch has the advantages of being portable and user-friendly. In addition, the pinch is cheap and allows for the standardization of the applied load.

Esteira com velocidade controlada para captação da marcha

Histological and electrophysiological methods for evaluation of peripheral nerve regeneration do not faithfully reproduce the functional index of limbs, even in controlled experimental conditions. Some methods of functional evaluation have been proposed, but their correlation to histological and electrophysiological data is not completely established, requiring more investigations with improvement of collection, management and processing of obtained data. In this study we developed a treadmill with controlled speed for recording footprint of rats submitted to different kinds of sciatic, fibular and tibial nerve lesions. The footprints were obtained on a walking track by means of a webcam connected to the treadmill and a computer with capacity to record the gait that will be submitted to functional evaluation. The developed treadmill allows the collection and filming of gaits and it has been tested in current experimental studies in rats with sciatic nerve lesion submitted to different kinds of treatment. The treadmill also enables researchers to record gait with constant, controlled and pre-established speed, with the possibility of direct visualization through the treadmill wall. In this manner, some variables that could damage the results of the research are resolved.

A comparative in vivo ultrasonometric evaluation of normal and delayed fracture healing in sheep tibiae

OBJECTIVE: To compare normal and delayed bone healing by measuring ultrasound conduction velocity across the bone callus. METHODS: A model of transverse linear and 5 mm resection osteotomies of sheep tibiae was used. Fourteen sheep were operated on and were divided into two groups of seven according to osteotomy type. The procedure was performed on the right tibiae and the intact left tibiae were used as controls. The transverse and axial ultrasound velocities were measured at 30-day intervals for 90 days, after which the animals were killed and both the right and left tibiae were resected for in vitro biomechanical analysis. RESULTS: Both the transverse and axial ultrasound velocities progressively increased, but the increase was smaller for the delayed union that resulted from the resection osteotomy. The mechanical resistance was higher for the normally healed tibiae that resulted from a linear osteotomy; this result closely correlated with the ultrasound velocity results. Significant differences were found for the comparisons between the intact and operated tibiae in both groups and between the groups for both the transverse and axial ultrasound velocities, but the differences were greater for the latter. CONCLUSION: We conclude that in vivo transverse and axial ultrasound velocities provide highly precise information about the healing state of both linear and resection diaphyseal osteotomies, but the axial ultrasound velocity most likely has greater discriminatory power. This method has the potential for clinical application in humans.

A new treadmill-type motorized walking belt machine for video recording of the rat's gait and sciatic functional index measurement. A comparative study with other methods

The sciatic functional index (SFI) is a remarkable tool to assess dysfunction and functional recovery of the sciatic nerve of rats. Usually measured on hind foot imprints on paper, a new method is now being proposed, by direct analysis of video recorded foot sole images obtained with a treadmill-type walking belt machine functioning with gait speed control (G1). Results were compared with the SFI measured on imprints on paper (G2) and on video recorded foot sole images obtained with a static see-through runway (G3). The right sciatic nerve of 19 adult female Wistar rats was crushed by the application of a controlled load. Impressions/images obtained both preoperatively and at weekly intervals for eight consecutive postoperative weeks were digitized, stored and analyzed in a computer loaded with specific software, the SFI being automatically calculated after measuring the appropriate parameters. SFI differed significantly between G1 and G2 and G1 and G3 (p<0.05), but not between G2 and G3 (p>0.05) during the first and second postoperative weeks, nonsignificant differences (p>0.05) being observed for any comparison between groups during the third through eighth postoperative weeks. We conclude that the three methods yielded equivalent results from the third week onward, but both video recording methods (G2 and G3) permitted a more adequate early evaluation (first and second weeks), since the SFI parameters were more easily identifiable. Images obtained with the walking belt machine are more uniform and sharper, thus contributing to reduce the influence of biases observed with imprints on paper.

Avaliação ultra-sonométrica da consolidação de osteotomias mediodiafisárias transversas em diferentes períodos: estudo experimental em tíbias de carneiro

Foi realizado um estudo experimental sobre a avaliacao ultra-sonometrica da consolidacao de tibias de carneiros submetidas a osteotomia transversal mediodiafisaria, utilizando 15 carneiros, com peso medio de 37 Kg, divididos em tres grupos experimentais de cinco animais cada, conforme o periodo de observacao pos-operatoria de 30, 45 e 60 dias. As osteotomias foram realizadas nas tibias direitas dos animais, ficando as tibias esquerdas como controle. Foi feita avaliacao radiografica da consolidacao a cada duas semanas e, ao fim do periodo de observacao, os animais foram sacrificados e as tibias, removidas para a analise ultra-sonometrica. Foram medidos e correlacionados o diâmetro da tibia e a velocidade de propagacao transversal do ultra-som na regiao da osteotomia, em duas direcoes diferentes (perpendicular e paralela ao plano da tuberosidade anterior da tibia). A velocidade de propagacao do ultra-som aumentou com o avancar da consolidacao (±5%), sendo as diferencas significantes em relacao ao grupo-controle, mas nao entre os grupo experimentais. Os diâmetros diminuiram nas duas direcoes medidas, sendo as diferencas significantes entre os grupos, com forte correlacao negativa com a velocidade. Concluiu-se que o metodo de avaliacao da consolidacao pela ultra-sonometria e factivel, com resultados confiaveis e precisos.

Correlation between ultrasound velocity and densitometry in fresh and demineralized cortical bone

OBJECTIVE: To compare ultrasound propagation velocity with densitometry in the diaphyseal compact cortical bone of whole sheep metatarsals. METHODS: The transverse ultrasound velocity and bone mineral density of 5-cm-long diaphyseal bone segments were first measured. The bone segments were then divided into four groups of 15 segments each and demineralized in an aqueous 0.5 N hydrochloric acid solution for 6, 12, 24 or 36 hours. All measurements were repeated after demineralization for each time duration and the values measured before and after demineralization were compared. RESULTS: Ultrasound velocity and bone mineral density decreased with demineralization time, and most differences in the pre- and post-demineralization values within each group and between groups were significant: A moderate correlation coefficient (r=0.75956) together with a moderate agreement was determined between both post-demineralization parameters, detected by the Bland-Altman method. CONCLUSION: We conclude that both ultrasound velocity and bone mineral density decrease as a result of demineralization, thus indicating that bone mineral content is of great importance for maintaining the acoustic parameters of cortical bone, as observed for cancellous bone. Ultrasound velocity can be used to evaluate both compact cortical bone quality and bone mineral density.

Influence of the osteosynthesis plate on ultrasound propagation in the bone

Objective: To analyze the influence of steel plates for osteosynthesis on the velocity of ultrasound propagation (VU) through the bone. Methods: The transverse coronal and sagittal velocity of ultrasound propagation underwater were measured on the intact bone and then on assemblies of the same bone with two types of osteosynthesis plates (DCP and semi tubular), fixed onto the dorsal side of the bones. The first arriving signal (FAS) was the ultrasound parameter used, taking the coronal and sagittal diameters as the distances to calculate velocity. Intergroup statistical comparisons were made at significance level of 1% (p<0.01). Results: Velocity was higher on the intact bones than on the bone-plate assemblies and higher for the semitubular than for the compression plates, although differences were not statistically significant for most comparisons (p=0.0132 to 0.9884), indicating that the steel plates do not interfere significantly with ultrasound wave propagation through the bone-plate assemblies. Conclusion: The velocity reduction effect was attributed to the greater reflection coefficient of the steel as compared to that of bone and water. Ultrasonometry can, thus, be used in the evaluation of healing of fractures fixed with steel plates. Experimental Study.