RESUMO

Objetivo: Evaluar si el tratamiento con ácido hialurónico reticulado bifásico de lesiones osteocondrales promovería la regeneración del tejido cartilaginoso, favoreciendo así la reparación de la lesión. Materiales y métodos: Quince conejos hembra adultos fueron divididos aleatoriamente en tres grupos: grupo 1, de control; grupo 2 y grupo 3, sometidos a una estrategia quirúrgica de lesión osteocondral en la rodilla derecha (4 mm de diámetro, 5 mm de profundidad), el grupo 3 recibió tratamiento con 0,2 ml de ácido hialurónico por vía intrarticular después de la cirugía. Se realizaron controles clínicos, bioquímicos, histopatológicos y estudios por imágenes. Resultados: Se detectaron menos casos de dolor a la palpación en el grupo 3 que en el grupo 2 a partir de los 45 días. En la resonancia magnética, casi todas las muestras del grupo 3 tenían signos de regeneración del tejido cartilaginoso en el sitio de la lesión, sin edema óseo, ni derrame articular significativo. Los estudios histopatológicos de las muestras del grupo 3 indicaron un aumento de la matriz extracelular propia de tejido cartilaginoso, comparada con la del grupo 2, con hipercelularidad, dada por condrocitos, los que formaban grupos isogénicos axiales y coronales. Conclusiones: Este estudio brinda evidencias de que el tratamiento con ácido hialurónico reticulado bifásico en unidades experimentales de conejos con lesión osteocondral no tuvieron dolor en etapas tempranas después de la lesión, a diferencia de las unidades intervenidas y sin dicho tratamiento. A su vez, los estudios por imágenes e histopatológico mostraron la reparación del tejido dañado.

Objective: To demonstrate whether treatment with biphasic cross-linked hyaluronic acid in osteochondral lesions promotes the regeneration of cartilage tissue. Materials and methods: Fifteen adult female rabbits were randomly assigned to three groups. G1 was the control group, whereas G2 and G3 underwent surgery to treat an osteochondral injury in the right knee (4mm diameter, 5mm depth). G3 received treatment with 0.2 ml of hyaluronic acid intrarticularly after surgery. Clinical, biochemical, histopathological controls and imaging studies were performed. Results:Clinically, G3 exhibited less pain on palpation than G2 after 45 days. In G3, almost all samples showed evidence of cartilage tissue regeneration at the injury site, with neither bone edema or considerable joint effusion detected on MRI. The histological tests of G3 samples revealed an increase in the extracellular matrix of cartilaginous tissue when compared to G2, with hypercellularity caused by chondrocytes that formed axial and coronal isogenic groups. Conclusions: This study provides evidence that treatment with biphasic cross-linked hyaluronic acid in experimental units of rabbits with osteochondral injuries did not cause pain in the early stages of the injury. In turn, imaging and histopathological studies revealed that the injured tissue had been repaired.

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RESUMO

To study the musculoskeletal effects of hypophysectomy (Hx) and a partial replacement treatment with recombinant human growth hormone (rhGH) in rats, we determined the stiffness (elastic modulus, E) and volumetric BMD (vBMD) of cortical bone; the periosteal and endosteal perimeters, area and bending moment of inertia (xCSMI) of the cross sections, and the structural stiffness and pre- and post-yield strength of the femur diaphyses by pQCT and mechanical tests, and the gastrocnemius weight of rats that were either intact (n = 9) or Hx at 15 days of age (20). The latter were otherwise untreated (Hx controls, 4) or given 0.4 (8) or 2.0 (8) IU kg(-1) day(-1), s.c., of rhGH for 45 days starting 15 days after surgery. Hx delayed musculoskeletal development (gastrocnemius weight, bone geometric properties), thus affecting the diaphyseal stiffness and strength. It also reduced the cortical vBMD through an undefined mechanism, and increased the elastic modulus of cortical bone. The Hx also affected the correlation between bone geometric and material properties (xCSMI vs. E), suggesting an antianabolic interaction with the biomechanical control of bone modeling in response to strains caused by mechanical usage. As a result, Hx reduced the stiffness, post-yield, and ultimate strength of the diaphyses. These effects should reflect changes in bone tissue microstructure, perhaps associated with crack generation and progress, but unrelated to bone mineral mass. They are compatible with the induction of a delay in collagen turnover with associated increases in fibers' diameter and crystals' size that may have resulted from the suppression of some other hormones, such as thyroid, prolactin, or other hormones regulated by ACTH. The above doses of rhGH significantly but incompletely prevented the negative Hx effects on bone and muscle development (bone geometric properties, muscle mass). However, rhGH treatment failed to prevent the demineralizing and stiffening effect of Hx on bone tissue and the unusual effects on the post-yield strength (less clearly related to muscle development than the former). Consequently, rhGH treatment tended to preserve the natural relationship between muscle function and bone geometry but not bone strength. The effects of larger rhGH doses and the interaction of other hormones with the described effects remain to be investigated. Nevertheless, these findings would deserve special attention because they challenge the prevailing view that in endocrine-metabolic bone-weakening diseases the bone matrix always has a normal composition.

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