Detecting early biomechanical effects of zoledronic Acid on femurs of osteoporotic female rats.

Aim. To investigate the biomechanical effects of zoledronic acid (ZA) on femurs of female osteoporotic rats after follow-up periods of 9 and 12 months. Methods. Eighty female Wistar rats were prospectively assessed. At 60 days of age, the animals were randomly divided into two groups: bilateral oophorectomy (O) (n = 40) and sham surgery (S) (n = 40). At 90 days of age, groups O and S were randomly subdivided into four groups, according to whether 0.1 mg/kg of ZA or distilled water (DW) was intraperitoneally administered: OZA (n = 20), ODW (n = 20), SZA (n = 20), and SDW (n = 20). The animals were sacrificed at 9 and 12 months after the administration of the substances, and then their right femurs were removed and analyzed biomechanically. Axial compression tests that focused on determining the maximum load (N), yield point (N), and stiffness coefficient (N/mm) of the proximal femur were performed in the biomechanical study. Results. ZA significantly increased the maximum load and yield point, reducing the stiffness coefficient concerning the oophorectomy status and follow-up period. Conclusion. Zoledronic acid, at a dose of 0.1 mg/kg, significantly increased the maximum loads and yield points and reduced the stiffness coefficients in the femurs of female rats with osteoporosis caused by bilateral oophorectomy.

Two-part surgical neck fractures of the humerus: mechanical analysis of the fixation with four Shanz-type threaded pins in four different assemblies.

The configuration of percutaneous pinning may affect the stability of the fixation of 2-part surgical neck fractures of the humerus. In this investigation, the mechanical properties of four different pin configurations were analyzed by use of 36 fresh-frozen swine femora as an experimental model. The bones were selected according to previously established morphologic parameters. A transverse osteotomy was made in the proximal metaphyseal region of the bone, and the pins were inserted according to the selected configuration (group 1, four ascending parallel pins; group 2, three ascending parallel pins and one descending intersecting pin; group 3, two ascending parallel pins and two descending parallel intersecting pins; and group 4, two ascending parallel pins and two descending converging pins, on different planes [two by two]). The assemblies were subjected to an axial load of up to 1500 N in a universal testing machine, simulating a varus stress. The parameters studied were the maximum load supported and corresponding deformation, load and deformation at the limit of proportionality, rigidity, and resilience. The results showed that all configurations were sufficiently strong, but the maximum load and load at the limit of proportionality were significantly higher (P < .05) in groups 3 and 4 (1314 and 1377 N and 950 and 923 N, respectively) than in groups 1 and 2 (1104 and 1033 N and 738 and 777 N, respectively). Rigidity was significantly higher in group 3 than in groups 1 and 2 but not in group 4. Resilience, maximum deformation, and deformation at the limit of proportionality were not significantly different between groups. We conclude that the experimental model used was reliable for the purpose of the study and that any of the configurations studied would be adequate for the percutaneous fixation of 2-part surgical neck fractures of the humerus but group 3 configuration would be the most efficient.

[Kinesiotherapy prevents shoulder pain in hemiplegic/paretic patients on sub-acute stage post-stroke]. / Cinesioterapia previne ombro doloroso em pacientes hemiplégicos/paréticos na fase sub-aguda do acidente vascular encefálico.

BACKGROUND: Painful shoulder is considered the most common complication of hemiplegic/parethic (H/P) stroke patients. It is a negative factor for neuromotor recovery. PURPOSE: To study the effects of kinesiotherapy treatment on shoulder pain prevention, and as a secondary endpoints, to analyze muscle strength of H/P shoulder looking at basic functional active mobility. METHOD: Twenty one inpatients (12 men, 9 women) aged 26 to 87 years, with post-stroke H/P were submitted to thirty minutes daily program kinesiotherapy, started at 48 hours post-stroke up to their hospital discharge. Patients were evaluated pre and post treatment according to the presence or absence of shoulder pain, movements and shoulder strength, and for presence or absence of basic functional movements. RESULTS: No patient complaining of shoulder pain at the hospital discharge (p<0.001). The muscle strength improved signifcantly for elevation, protusion, abduction and flexion of the shoulder (p<0.001). There was improvement also for functional mobility on moving from dorsal to lateral recumb, from lateral recumb to a seated position and in keeping the seated position (p<0.001). CONCLUSION: Kinesiotherapy in acute phase of stroke prevented shoulder pain.