Objective?To analyze the effect of different surgery techniques on the tendon-bone healing of rotator cuff insertion.?Methods?Forty-two adult Japanese rabbits, weighing 2.0-2.5 kg and male or female, were selected. Thirty-six rabbits were given a sharply left-lateral tenotomy of the supraspinatus tendon with subsequent re-attachment of the tendon. According to the depth of re-attachment, 36 rabbits were equally randomized into the cancellous-fixation group (a cancellous bed was prepared with a dental burr) and the cortical-fixation group (the same treatment was performed except the preparation of the bone bed). Six rabbits served as the controls without treatment (control group). At 4 and 8 weeks after operation, the general observation, HE staining, and the biomechanical test were performed.?Results?At 4 weeks after operation, the supraspinatus-humerus specimens morphologically showed atrophy and vague between tendon and new bone in the cancellous-fixation group and the cortical-fixation group; at 8 weeks, no obvious difference was observed between 2 groups and the control group. The histological results of the cortical-fixation group at 4 weeks revealed the interface between tendon and new bone became smooth. The interface became transitional at 8 weeks, and the shape of bone tissue was nearly normal. The interface obtained from the cancellous-fixation group at 4 weeks became sclerotic, and collagen fibers formed in disorder. With ingrowth of new bone and re-establishment of collagen-fiber continuity at 8 weeks, thickness of interface became thin, and bone tissue was remodeling. The ultimate load were significantly higher in the cortical-fixation group than in the cancellous-fixation group at both 4 and 8 weeks, and the results gained at 8 weeks is significantly higher than that at 4 weeks in each group (P lt; 0.05). Except rupture strength at 4 weeks between 2 groups and all tensile strength (P gt; 0.05), there were significant differences in the results of others (P lt; 0.05).?Conclusion?In this model, the tendon-bone healing process and the biomechanical properties of cortical-fixation is superior to those of cancellous-fixation.
Objective To explore the biomechanical difference between the different fixations of cortical bone plate allograft. Methods Twenty-seven cadaveric femurs were harvested and were made into the simulated fracture models, which were equally divided into Groups A, B and C. In Group A, the models were fixed with 2 bone plate allografts (110 mm×10 mm×3 mm); in Group B, the models were fixed with 2 struts (110 mm×10 mm×3 mm) and 5 bone screws; in Group C, the models were fixed with 1 strut (110 mm×10 mm×3 mm) and 5 bone screws. The biomechanical tests for the three-piont bending, torsion, and compression were performed. The parameters studied included the values of the displacements in the three-piont bending tests and the compression tests, and the maximum loads during the bending, the compression, and the torsion. Results As for all the stiffness parameters tested, Group A showed the greatest displacements among the threegroups（P＜0.05）, except the compressive stiffness parameter, which was similar to that in Group B. The maximum loads of the three-point bending, the torsion, and the compression in Group A were 1.65±0.34 kN, 554.3±49.34 N, and 7.78±0.82 Nm, respectively; in Group B, they were 1.12±0.37 kN, 428.00±37.40 N,and 3.39±0.22 Nm, respectively; in Group C, they were 0.71±0.46 kN, 218.67±36.53N, and 1.74±0.12 Nm, respectively. Group A had a significantly greater strengththan the other 2 groups(P＜0.05). Conclusion The strength of the cortical bone plate allograft is related to its different fixations. The two cortical bone plate allografts have a greater strength and stiffness than the struts fixed with the bone screws, which can meet the clinical requirement.
Objective To study the effect of vascular endothelial cell growth factor (VEGF) on repair of bone defect with cortical bone allograft. Methods Forty five New Zealand white rabbits, weighted 2.5-3.0 kg, were made bone defect model of 1.5 cm in length in the bilateral radii and then were randomly divided into 3groups. The defect was repaired with only cortical bone allograft in the control group, with the cortical bone allograft and local injection of human recombinantVEGF in the experimental group, and with the cortical bone allograft and abdominal injection of VEGF PAb3 in the antagonist group. Roentgenography, immunohistochemical staining and tetracycline labelling were carried out to evaluate the reparative results 1, 3, 5, 8 and 16 weeks after operation. Results Immunohistochemical staining results showed that a great deal of blood vessels formed in the experimental group, and the number of blood vessels increased gradually with the time and reached the highest value at the 8th week. Tetracyclinelabelling showed the same result.The best results in callus formation, ossification rate and count of microvascular density were shown in the experimental group, while those in the control group were significantly better than those in the antagonist group (Plt;0.05),but there was no significant difference between the experimental group and the control group at the 8th week and the 16th week (Pgt;0.05). Conclusion VEGF can accelerates the bone formation and angiogenesis in the bone allografts, thus it can promote the repair of bone defects.
ObjectiveTo summarize the effectiveness of anatomical plate combined with cortical bone plate allografts in the treatment of comminuted fractures of the femoral condyles. MethodsBetween January 2008 and December 2012, 18 patients with comminuted fractures of the femoral condyles were treated, including 13 males and 5 females with an average age of 45 years (range, 23-65 years). Fractures were caused by traffic accident in 11 cases, by falling from height in 4 cases, and by the other in 3 cases. The locations were the left side in 7 cases and the right side in 11 cases. Of 18 fractures, 12 were open fractures and 6 were closed fractures. The mean time from injury to operation was 6 days (range, 4-15 days). The fixation was performed by anatomical plate combined with cortical bone plate allografts, and autograft bone or allogeneic bone grafting were used. ResultsSuperficial local skin necrosis occurred in 1 case, and was cured after skin graft, and other incisions achieved primary healing. All patients were followed up 12-36 months (mean, 23 months). X-ray films showed that bone union was achieved within 3-12 months (5.6 months on average). No related complication occurred, such as fixation loosening, refracture, infection, or immunological rejection. According to Merchan et al. criteria for knee joint function evaluation, the results were excellent in 7 cases, good in 9 cases, fair in 1 case, and poor in 1 case at last follow-up; the excellent and good rate was 88.9%. ConclusionAnatomical plate combined with cortical bone plate allograft fixation is a good method to treat comminuted fractures of the femoral condyles. This method can effectively achieve complete cortical bone on the inside of the femur as well as provide rigid fixation.
ObjectiveCT three-dimensional reconstruction technology was used to simulate the placement of the lumbar cortical bone trajectory (CBT), to determine the starting point and direction of the screw trajectory.MethodsBetween February 2017 and April 2018, 24 patients with lumbar CT were selected as the study object. There were 7 males and 17 females, with an average age of 50.4 years (range, 37-68 years). The CT DICOM data of patients were imported into Mimics 16.0 software, and the three-dimensional model of lumbar spine was established. A 5 mm diameter cylinder was set up to simulate the CBT by using Mimics 16.0 software. According to the different implant schemes, the study was divided into groups A, B, and C, the track of the screw respectively passed through the upper edge, the medial edge, and the lower edge of the isthmus of the pedicle. The intersection of simulated screw and lumbar spine was marked as region of interest (ROI) and a mask was generated. The average CT value [Hounsfield unit (HU)] and the screw length of ROI were automatically measured by Mimics 16.0 software. In addition, the head inclination angle and head camber angle of the screw were measured respectively. Point F was the intersection of the level of the lowest edge of the transverse process and the lumbar isthmus periphery. The horizontal and vertical distance between point F and the starting point were measured, and the relationship between the three schemes and the position of the zygapophysial joint and spinous process was observed.ResultsPlan A has the highest ROI average HU, with the maximum value appearing in L4; plan B has the longest screw length, with the maximum value appearing in L5; plan C has the largest nail track head inclination angle, with the maximum value appearing in L4; plan B has the largest nail track head camber angle, with the maximum value appearing in L3. The screw length and head camber angle of the nail in group B were significantly greater than those in groups A and C (P<0.05); the head inclination angle in groups A, B, and C was gradually increased, showing significant differences (P<0.05); there was no significant difference in the average HU value of ROI between the 3 groups (P>0.05). In plan A, 74.48% (143/192) screws had a horizontal distance of −2 to 4 mm from point F, a vertical distance of 6-14 mm from point F, a head inclination angle of (14.64±2.77)°, and a head camber angle of (6.55±2.09)°, respectively; in plan B, 84.58% (203/240) screws had a horizontal distance of 1-6 mm from point F, a vertical distance of 1-5 mm from point F, a head inclination angle of (26.93±2.21)°, and a head camber angle of (10.29±2.46)°, respectively; in plan C, 85.94% (165/192) screws had a horizontal distance of −2 to 3 mm from point F, a vertical distance of −2 to 4 mm from point F, a head inclination angle of (33.50±3.69)°, and a head camber angle of (6.47±2.48)°, respectively.ConclusionPlan B should be selected as the starting point of the L1-L5 CBT implant. It is located at the intersection of the lowest horizontal line of the transverse process root and the lateral edge of the lumbar isthmus, which is 1-6 mm horizontally inward, 1-5 mm vertically upward, with a head inclination angle of (26.93±2.21)°, and a head camber angle of (10.29±2.46)°, respectively.