Temporal and Spatial Expression of TGF-b1 in the Early Phase of Patellar Tendon Healing after Application of Platelet Rich Plasma.

BACKGROUND: The aim of this study is to find out the spatial and temporal expression of TGF-b1 during the tendon healing, after application of Platelet Rich Plasma (PRP). METHODS: A patellar tendon defect model in rabbits was used for this purpose. 48 skeletally mature New Zealand White rabbits, weighing 3.5 kg, were used for this study. Equal numbers of animals from both groups were sacrificed at 4 different time points (1st, 2nd, 3rd, and 4th week). A full thickness patellar tendon substance in the right limb of each animal was excised from its central portion during the operation. PRP with a gel form was applied and filled the tendon defect in PRP group. No PRP was applied in the tendon defect of controls. Histological sections with hematoxylin-eosin and immunohistochemical sections with an anti-TGF-b1 primary antibody were made for the evaluation of the results. RESULTS: A differentiation of the healing process was observed in the PRP group in comparison with the control group. TGF-b1 expression was detected in various cell populations (inflammatory cells, endothelial cells, macrophages, and tenocytes). Both cytoplasmic and nuclear expressions were present. The larger amounts of immunoexpression were localized in epitenon and in the repair site. PRP group showed stronger and more extensive staining at 1st and 2nd week (P<0.0001), whereas control group showed more extensive staining at the 3(rd) and 4(th) week (P<0.0001). CONCLUSIONS: Our study demonstrates that locally application of PRP result in an alteration of TGF-b1 expression during the healing of a patellar tendon defect.

Application of PRP gel alone or in combination with guided bone regeneration does not enhance bone healing process: An experimental study in rabbits.

INTRODUCTION: The aim of this study was to assess the hypothesis that application of platelet-rich plasma (PRP) gel in mandibular defects in rabbits, alone or in combination with guided bone regeneration (GBR) techniques, could enhance the bone healing process. MATERIALS AND METHODS: Thirty New Zealand white rabbits were used. Three groups of 10 animals each were assigned, and the animals were sacrificed after 12 weeks. During the operation, a rotating trephine bur was used to create circular defects 10-mm in diameter in the region anterior to the jaw angles. In group human fascia lata (HFL), a human fascia lata membrane was used. In group PRP, PRP gel was used to fill the defect, and in group HFL+PRP, PRP was used to fill the defect which after that was covered with a human fascia lata membrane. RESULTS: In general, none of the control sides and the PRP treated sides had full development of bone or filling of the defect through bone bridging. Conversely, the sides on which the fascia lata membrane or the combination of membrane and PRP had been applied were characterized mostly by development of newly formed bone that bridged the gap. CONCLUSIONS: Our results suggest that the application of PRP gel alone or in combination with GBR does not enhance bone healing process.

Temporal and spatial expression of TGF-beta1 in an Achilles tendon section model after application of platelet-rich plasma.

BACKGROUND: To investigate the effect of platelet-rich plasma (PRP) on TGF-beta1 expression during tendon healing. METHODS: We used 48 skeletally mature New Zealand White rabbits. 24 rabbits received the PRP, and 24 rabbits served as an untreated control group. Equal numbers of animals were sacrificed at 1st, 2nd, 3rd, and 4th week. The surgical procedure involved a transverse incision to transect the Achilles tendon. A volume of 1ml of PRP was then injected into the tendon mass in the PRP group. Histological and immunohistochemical evaluations with an anti-TGF-beta primary antibody were performed. RESULTS: The pattern of expression of TGF-beta1 in the PRP group was characterized by a significant upregulation during the first 2 weeks and subsequently significant downregulation in the 3rd and 4th week in comparison with the controls. CONCLUSIONS: Our results suggest that PRP may affect the tendon healing process by altering the expression of TGF-beta1.

Immunohistochemical study of angiogenesis after local administration of platelet-rich plasma in a patellar tendon defect.

A full thickness defect was made in the central portion of the patellar tendon of 48 New Zealand white rabbits. Platelet-rich plasma (PRP) gel was then applied and filled the tendon defect. The same procedure was performed in the control group, without the application of PRP. Animals were sacrificed after one, two, three, and four weeks. Histological and immunohistochemical analyses using a monoclonal antibody against CD31 were performed. The histological examination showed a superior healing process in the PRP group compared with the control group. Especially in the third week, the tissue formed in the PRP group was more mature and dense with less elastic fibres remaining. Neovascularisation was significantly higher in the PRP group during the first two weeks and significantly lower in the third and fourth weeks (p < 0.0001). Histological examination and study of angiogenesis showed that the application of PRP enhances and accelerates the tendon healing process.

The influence of platelet-rich plasma on angiogenesis during the early phase of tendon healing.

BACKGROUND: The poor vascularity of tendons is a major factor in their limited healing capacity. The aim of this study was to assess the effect of Platelet Rich Plasma (PRP) on angiogenesis during tendon healing. MATERIALS AND METHODS: Forty-eight skeletally mature New Zealand White rabbits were used. The Achilles tendon was transected transversely and 0.5 ml of PRP was injected into the tendon mass on each side of the incision on both limbs. The injection in the control group consisted of saline. Six animals from each group (12 tendons each) were sacrificed after 1, 2, 3, and 4 weeks following treatment. Three sections from each Achilles were stained with hematoxylinosin for microscopic examination. Further three sections were immunostained with a monoclonal antibody against CD31 (Daco Co), followed by image analysis to count new vessel numbers and statistical analysis was performed. RESULTS: There was significantly more angiogenesis in the PRP group compared to the control group during the first two weeks of the healing process, i.e., inflammatory and proliferative phase (p < 0.0001). The orientation of collagen fibers in the PRP group was better organized. The number of the newly formed vessels in the PRP group were significantly reduced at 4 weeks compared to the controls (p < 0.0001) suggesting the healing process was shortened. CONCLUSION: PRP seems to enhance neovascularization which may accelerate the healing process and promote scar tissue of better histological quality. CLINICAL RELEVANCE: Although these results need replication and further biomechanical research, PRP may promote tendon healing acceleration.

The effect of platelet-rich plasma gel in the early phase of patellar tendon healing.

INTRODUCTION: The aim of this study is to assess if an application of platelet-rich plasma (PRP) gel would improve the mechanical properties of rabbit's patellar tendon after resecting its central portion. MATERIALS AND METHODS: Forty skeletally mature New Zealand White rabbits were used. Two groups ten rabbits each (PRP and control group) were used to evaluate mechanical properties and histology after 14 days and two groups ten rabbits each (PRP and control groups) were used to evaluate mechanical properties and histology after 28 days. RESULTS: At 14 days, PRP group showed a 72.2% increase in force at failure, a 39.1% increase in ultimate stress, and a 53.1% increase in stiffness, as compared with controls. These changes were statistically significant (P < 0.05). At 28 days, there was no longer any significant difference between PRP and control groups (P > 0.05). DISCUSSION: In our study, the mechanical properties of the regenerated tendon in the PRP group were significantly improved in relation to the control group. It appears that PRP has a strong effect in the early phase of tendon healing. This effect is probably due to the growth factors that are released from the platelets during activation.

Fractures of the femoral neck treated with hemiarthroplasty. A comparative study.

INTRODUCTION: Hemiarthroplasty is the treatment of choice in the management of displaced intracapsular fractures of the proximal femur in old patients with low functional demands. AIM: To assess the effectiveness of cementless Austin-Moore and the cemented Thompson prostheses used in the treatment of displaced intracapsular fractures of the proximal femur. PATIENTS AND METHODS: We studied retrospectively 376 patients with fresh, displaced, nonpathological femur neck fractures. They were treated with either a cementless Austin-Moore prosthesis or a cemented Thompson prosthesis. Criteria for the choice of the prosthesis were the fracture site on the neck of the femur and the bone quality. The follow-up period was 3 to 8 years and the number of reviewed patients was 122. RESULTS: The Thompson prosthesis group showed slightly better results. Acetabular erosion rate was significantly lower in the uncemented group while loosening rate here was significantly higher. CONCLUSION: Advantages and disadvantages were identified in both groups although we believe that none of the approaches proved definitively superior to the other.