The Effects of Adipose Derived Stromal Vascular Fraction and Platelet-Rich Plasma on Bone Healing of a Rat Model With Chronic Kidney Disease.

BACKGROUND: Chronic kidney disease (CKD) impairs osteoblast/osteoclast balance and damages bone structure with diminished mineralization and results in bone restoration disorders. In this study, we investigate the effects of adipose-derived stromal vascular fraction and platelet-rich plasma (PRP) on bone healing model in rats with CKD. METHODS: Sprague-Dawley rats were separated into 4 groups. All groups except group I (healthy control) had CKD surgery using 5/6 nephrectomy model. All groups had intramedullary pin fixation after receiving bone fracture using drilling tools. Group II rats were used as control group for CKD. Group III rats received PRP treatment on fracture site. Group IV rats received PRP and stromal vascular fraction treatment on fracture site.Weight loss and blood samples were followed at the time of kidney surgery, third, sixth, and 12th weeks. Bone healing and callus formations were compared, biomechanically, radiologically, histopathologically, and immunohistochemically. Osteoblastic transformation of stem cells was assessed with DiI staining. RESULTS: Negative effects of CKD on bone healing were reduced by increasing mechanical, histological, radiological, and biochemical properties of the bone with stromal vascular fraction and PRP treatments. Although thickness of callus tissue delayed bone healing process, it also enhanced biomechanical features and bone tissue organization. CONCLUSIONS: Platelet-rich plasma and adipose-derived stromal vascular fraction treatments were effective for bone healing in animal model, which can be promising for clinical trials.

The effects of extracorporeal shock waves on carrageenan-induced Achilles tendinitis in rats: a biomechanical and histological analysis.

OBJECTIVE: The aim of this study was to investigate the influence of low-dose extracorporeal shock waves (ESW) on the healing potential of Achilles tendinitis in the rat. METHODS: The 36 adult Sprague-Dawley rats used in this study were randomly divided into four groups. Group A (n=10) were injected with carrageenan, Group B (n=10) were injected with carrageenan and received ESW, Group C (n=10) received ESW only, and Group D (n=6) was a sham group. Rats were injected with 10 microliters of 3% carrageenan or a saline solution eight times during a one-week period with a subcutaneous needle. One week following the final injection, ESW was applied at a rate of 500 impulses in 5 minutes at 2 bars (comparative to 0.09 mJ/mm²) to rats in Groups B and C. Rats were sacrificed three weeks later. Tensile strength, inflammation, and vascularity and collagen density were measured. RESULTS: Failure of the tendon ultimate loads was significantly lower in the study groups than in the control group (p<0.05). Collagen fiber density was higher in the control group than in the other groups (p=0.59). No other histological differences were found. CONCLUSION: Low-dose ESW has a negative effect on tendon tensile strength in this animal model.

Comparison of repair techniques in small and medium-sized rotator cuff tears in cadaveric sheep shoulders.

OBJECTIVE: The aim of this study was to compare new knotless single-row and double-row suture anchor techniques with traditional transosseous suture techniques for different sized rotator cuff tears in an animal model. METHODS: The study included 56 cadaveric sheep shoulders. Supraspinatus cuff tears of 1 cm repaired with new knotless single-row suture anchor technique and supraspinatus and infraspinatus rotator cuff tears of 3 cm repaired with double-row suture anchor technique were compared to traditional transosseous suture techniques and control groups. The repaired tendons were loaded with 5 mm/min static velocity with 2.5 kgN load cell in Instron 8874 machine until the repair failure. RESULTS: The 1 cm transosseous group was statistically superior to 1 cm control group (p=0.021, p<0.05) and the 3 cm SpeedBridge group was statistically superior to the 1 cm SpeedFix group (p=0.012, p<0.05). The differences between the other groups were not statistically significant. CONCLUSION: No significant difference was found between the new knotless suture anchor techniques and traditional transosseous suture techniques.

Effect of static magnetic field on experimental dermal wound strength.

CONTEXT: An animal model. AIM: We sought to evaluate the effect of static magnetic fields on cutaneous wound healing. MATERIALS AND METHODS: Male Wistar rats were used. Wounds were created on the backs of all rats. Forty of these animals (M group) had NeFeB magnets placed in contact with the incisions, either parallel (Pa) and perpendicular (Pr) to the incision. The other 40 animals (sham [S] group) had nonmagnetized NeFeB bars placed in the same directions as the implanted animals. Half of the animals in each group were killed and assessed for healing on postoperative day 7 and the other half on postoperative day 14. The following assessments were done: gross healing, mechanical strength, and histopathology. STATISTICAL ANALYSIS USED: Intergroup differences were compared by using the Mann-Whitney U or t test. Values for P less than 0.05 were accepted as significant. RESULTS AND CONCLUSIONS: There were no differences between the magnetic and sham animals with respect to gross healing parameters. The mechanical strength was different between groups. On postoperative day 14, the MPr14 had significantly higher scores than the other groups. When static, high-power, magnetic fields are placed perpendicular to the wound, increased wound healing occurs in the skin of the experimental model.

Comparison of fixation stability of resorbable versus titanium plate and screws in mandibular angle fractures.

PURPOSE: The aim of this study was to compare the fixation reliability and stability of titanium and resorbable plates and screws by simulating chewing forces. MATERIALS AND METHODS: Mandibular angle fractures in 11 sheep hemimandibles were fixed with 4-hole straight titanium plates and 2.0 x 7-mm titanium screws; in addition, 11 hemimandibles were fixed with 4-hole straight resorbable plates and 2.5 x 6-mm resorbable screws according to the Champy technique. The hemimandibles were mounted with a fixation device in a servohydraulic testing unit for compressive testing. Displacement values under 20, 60, 100, 120, 150, and 200 N; maximum displacements; and maximum forces that the model could resist before breakage were recorded and compared. RESULTS: Significant differences were found between resorbable and titanium plates and screws at all forces (20, 60, 100, 120, 150, and 200 N) (P < .05). We found no statistically significant differences in the breaking force and maximum displacement values (displacement values at the breaking forces) between the groups. CONCLUSIONS: The stability of mandibular angle fractures with titanium miniplates under simulated chewing forces was significantly higher than with the resorbable system. Metallic and resorbable fixation systems cannot be used interchangeably to treat mandibular angle fractures under similar loading conditions.

Biomechanical and histological comparison of the influence of oestrogen deficient state on tendon healing potential in rats.

Thirty-six female Sprague-Dawley rats were divided into two groups: oophrectomised (oestrogen deficient) rats and sham operated (oestrogen maintained) rats. Rats were sacrificed at six, ten, and 14 weeks. The rats were randomly chosen to have biomechanical evaluation on one side and histological evaluation on the other. Biomechanical testing was performed on an Instron machine to measure peak load. Histological sections were evaluated for cell proliferation, collagen-fibre organisation, fibroblast density, angiogenesis, inflammatory cells, chondroid and osseous metaplasia. Compared with the sham operated group, the oophrectomised group showed a lesser average maximum stress (42.9 N/m(2) versus 33.7 N/m(2)) at six weeks, which was significant (p < .05). Succeeding weeks showed no significant biomechanical differences between the two groups. The sham operated group showed greater inflammatory response, which was statistically significant (p < 0.05), and also revealed greater cell proliferation and density. The results of this study revealed that endogenous oestrogen may improve healing of the Achilles tendon in rats.

Early weight bearing of porous HA/TCP (60/40) ceramics in vivo: a longitudinal study in a segmental bone defect model of rabbit.

Porous interconnected hydroxyapatite (HA) and HA/tricalcium phosphate (TCP) (60/40) ceramics are promising materials for hard tissue repair. However, the mechanical properties of these materials have not been accurately determined under weight-bearing conditions. In this study, newly developed HA and HA/TCP (60/40) ceramics were used with intramedullary fixation in segmental bone defects of rabbits. Early radiological, histological, densitometric and biomechanical changes were evaluated. The mean radiological grade of healing and bonding to bone was higher in HA/TCP (60/40) ceramics than that of pure HA ceramics but the difference was not statistically significant. The densities of both implanted ceramics improved with time, supported by the histological evaluation of bone matrix ingrowth into ceramic pores, whereas the densities at the bone-ceramic interface decreased gradually. Flexural resonant frequencies and three-point bending strength increased, revealing an increase in mechanical stability during this early critical time interval where implant and/or bone-implant interface failures occur frequently. It can be concluded that both HA and HA/TCP (60/40) ceramics have a limited application in the treatment of load-bearing segmental bone defects but did not fail at the early stages of implantation.

Mechanical strength of four different biceps tenodesis techniques.

PURPOSE: The aim of this study was to compare the biomechanical properties of 4 different biceps tenodesis techniques. TYPE OF STUDY: Biomechanical experiment. METHODS: Four groups of fresh sheep shoulders (28 total) with similar shape characteristics were used. Biceps tenodesis was performed using the following techniques: group 1 (n = 7), tunnel technique; group 2 (n = 7), interference screw technique; group 3 (n = 7), anchor technique; and group 4 (n = 7), keyhole technique. Each construct was loaded to failure and the groups were compared with respect to maximum load in Newtons and deflection at maximum load in millimeters. The results were statistically analyzed with 1-way analysis of variance, the Bonferroni post hoc test and the Student t test or the nonparametric Mann-Whitney U test. RESULTS: The calculated average maximum loads were 229.2 +/- 44.1 N for the tunnel technique, 243.3 +/- 72.4 N for the interference screw, 129.0 +/- 16.6 N for the anchor technique, and 101.7 +/- 27.9 N for the keyhole technique. Statistical testing showed no statistically significant differences between groups 1 and 2, groups 3 and 4, or groups 2 and 3 with respect to maximum load and deflection at maximum load (P = .09/P = .49, P = .41/P = .79, and P = .06/P = .82 for load/deflection in the 3 comparisons, respectively). However, all other group comparisons revealed significant differences for both parameters (group 1 v group 4 [P < .01/P < .01]; group 1 v group 3[P < .01/P = .01]; and group 2 v group 4 [P = .007/P = .003]). CONCLUSIONS: The strongest construct was made with the interference screw technique, followed by the tunnel, anchor, and keyhole techniques. There were no statistically significant differences between the interference screw and tunnel techniques with respect to maximum load or deflection at maximum load. CLINICAL RELEVANCE: Although it is difficult to extrapolate in vitro data to the clinical situation, the interference screw technique has better initial biomechanical properties and may produce improved clinical outcomes.