Objective To investigate the effect of canine decellularized tendon slices (DTSs) on tendon-bone healing in repairing rotator cuff injury of rabbit. Methods Canine DTSs were prepared by repetitive freeze/thaw 5 times combined with nuclease processing for 12 hours from the adult Beagles Achilles tendons. Histological observation and cytocompatibility evaluation for the canine DTSs were performed in vitro. Twenty-four mature male New Zealand white rabbits, weighing 2.5-3.0 kg, were randomly selected. U-shaped defect of more than 50% of normal tendon in width and 8 mm in length was made in infraspinatus tendons of unilateral limb as the experimental group; the canine DTSs were used to repair defect, and the insertion of infraspinatus tendon on greater tuberosity of humerus was reconstructed in the experimental group. No treatment was done on the contralateral limb as the control group. At 4, 8, and 12 weeks after operation, the specimens were harvested for histological observation and biomechanical test. Results Histological examination showed that collagen fibers of canine DTSs were well preserved, without residual cells. The cytocompatibility examination showed that fibroblasts attached well to canine DTSs. Biomechanical test showed that the maximum load and stiffness increased significantly with time, and the maximum load and stiffness at 12 weeks were significantly higher than those at 4 and 8 weeks (P lt; 0.05). The maximum load and stiffness of the experimental group at 4 and 8 weeks were significantly lower than those of the control group (P lt; 0.05). The stiffness of the experimental group at 12 weeks was significantly lower than that of the control group (t= — 5.679, P=0.000), but no significant difference was found in the maximum load at 12 weeks between 2 groups (t=0.969, P=0.361). Histological observation showed that the control group displayed a 4-layer structure of the tendon-bone insertion. In the experimental group at 4 weeks, the tendon-bone interface was filled with granulation tissue, and a small amount of Sharpey’s fibers-like connected the tendon to bone; granulation tissue disappeared, and fibroblasts, Sharpey’s fiber, new cartilage, and chondrocytes significantly increased with time; tendon-bone interface became mature, but the tide line was not observed between the unmineralized fibrocartilage and mineralized fibrocartilage. Conclusion Canine DTSs prepared by repetitive freeze/thaw 5 times combined with nuclease processing for 12 hours, can enhance the healing of host tendon-bone and improve the biomechanical characteristics of the rabbit infraspinatus tendon.
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 investigate and compare the difference between two implants of reconstructing anterior cruciate l igament (ACL) for the early heal ing of implants tunnel interface in terms of biological mechanism. Methods Fiftyfive adult New Zealand rabbits weighing 2.0-2.8 kg were selected. Patellar l igament with tibia-bone block was obtained fromthe left knee joint serving as donor site, right knee joint served as the recipient site of autograft for ACL reconstruction. Thebone block end of implant was bone-bone interface heal ing model, while the l igament end was tendon-bone interface heal ing model. The general condition of rabbits was observed after operation, the gross observation and histology observation were conducted at 2, 4 and 8 weeks after operation (n=5), and biomechanics examination was conducted at 4 and 8 weeks after operation (n=20). Results Rabbits behaved normally after operation. The gross observation indicated that ACL had complete continuity and moderate tension during experiment. Histology observation: most part of bone-bone interface was connected by fibrous tissue, while the tendon-bone interface was mainly filled by granulation tissue 2 weeks after operation; most part of bone-bone interface was bone union, and there were osteogenesis reaction and large quantity of fibroblasts in the tendonbone interface 4 weeks after operation; complete bone union was evident in bone-bone interface, and the appearance of Sharpey fibers and the formation of indirect insertion occured in part of tendon-bone interface 8 weeks after operation. Biomechanics observation: the pull-out rate for tendon-bone interface and bone-bone interface 4 weeks after operation was 85% and 15%, respectively; while it was 95% and 5% 8 weeks after operation, respectively; indicating there was a significant difference between two groups (P lt; 0.001). Conclusion In the early stage after ACL reconstruction, bone-bone interface is better than tendonbone interface in terms of intensity and speed of heal ing.
ObjectiveTo investigate the effect of hamstring tendon transfected with adenovirus-mediated transforming growth factor β1 (AdTGF-β1) genes on the histomorphology of tendon-bone interface healing after anterior cruciate ligament (ACL) reconstruction in rabbits. MethodsAdTGF-β1 and AdGFP were diluted to 5×108 PFU/mL with DMEM. Forty-eight New Zealand white rabbits were divided into 3 groups randomly (n=16), weighing 1.6-2.5 kg for ACL reconstruction with hamstring tendon autograft. Hamstring tendon was cultured and transfected with AdTGF-β1 (group A) and AdGFP (group B) for 12 hours before ACL reconstruction, and was cultured with DMEM in group C. After 12 hours of transfection, the expression of green fluorescence was observed in groups A and B under fluorescence microscopy; TGF-β1 protein level was detected by ELISA in group A. At 2, 4, 8, and 12 weeks after operation, the specimens were harvested for HE and Masson staining; the number of fibroblasts was counted, and the Buark grading was used to evaluate tendon-bone interface healing. ResultsGreen fluorescence was observed after 12 hours of transfection in groups A and B. TGF-β1 protein level reached (221.0±12.2) ng/mL at 12 hours in group A. The histological observation showed that few fibroblasts and collagen fibers were found, and Sharpey fibers appeared in group A; regular Sharpey fibers were seen in the interface, and integrity interface in some areas at 12 weeks. But fibroblasts of groups B and C were less than those of group A, with loose tendon-bone interface; no integrity interface was observed at 12 weeks. The number of fibroblasts and Buark grading of group A were significantly higher than those of groups B and C (P<0.05), but no significant difference was found between groups B and C (P>0.05). ConclusionHamstring tendon transfected with AdTGF-β1 gene can promote the healing of tendon-bone interface after ACL reconstruction.
ObjectiveTo summarize the application status and progress of the strategies to augment tendon-to-bone healing. MethodsThe present researches focused on augmentation of tendon-to-bone healing were extensively reviewed. ResultsThe present strategies to augment healing of tendon-to-bone by enhancing the location environment, and increasing the cell numbers and relative growth factor. The mainly strategies include using calcium phosphate materials, biocompatible scaffolds and glue, growth factors, cell matrix, platelet-rich plasma, and periosteum. Although periosteum have been used in clinical and got some possitive effects, the others still not be used in clinical and needs further studies. ConclusionThere are many strategies to enhance the ability of tendon-to-bone healing, which got some positive results, but results of studies were varied. Thus, further fundamental research and clinical studies are required to achieve the best effects.
ObjectiveTo observe the effect and significance of autologous fibrin clot on tendon-bone healing after anterior cruciate ligament (ACL) reconstruction.MethodsBetween October 2014 and January 2016, 34 patients (34 knees) with ACL injury were enrolled in the study. During ACL reconstruction, autologous fibrin clot was used in 17 cases (trial group) and was not used in 17 cases (control group). The anterior drawer test, Lachman test, and axial displa-cement test were positive in 2 groups before operation. There was no significant difference in gender, age, causes of injury, injury side, disease cause, and preoperative knee joint activity, Lysholm score, and American Hospital for Special Surgery (HSS) score between 2 groups (P>0.05), with comparable. The results of anterior drawer test, Lachman test, and axial displacement test were recorded and compared between 2 groups after operation. The knee joint activity, Lysholm score, and HSS score were used to evaluate the knee function recovery at 6, 24, and 48 weeks after operation; the graft signal intensity, graft signal to noise ratio, bone tunnel expansion, and graft tendon-bone node T2 value were measured.ResultsAll patients were followed up 48 weeks. Surgical incision healed at stage I. No joint infection and joint adhesion occurred. The drawer test, Lachman test, and axial shift test were negative in 2 groups. At 6, 24, and 48 weeks after operation, the Lysholm score of trial group was significantly higher than that of control group (P<0.05); there was no significant difference in knee joint activity between 2 groups (P>0.05). The HSS score of trial group was significantly higher than that of control group at 24 and 48 weeks (P<0.05), but no significant difference was found at 6 weeks (P>0.05). MRI measu-rement showed that there was significant difference in graft signal intensity, bone tunnel expansion, and graft signal to noise ratio between 2 groups at 6, 24, and 48 weeks after operation (P<0.05). There was no significant difference in graft tendon-bone node T2 value between 2 groups (P>0.05) at 48 weeks after operation, but difference was significant at 6 and 24 weeks (P<0.05).ConclusionAutologous fibrin clot can effectively enhance graft revascularization, and accelerate the process of tendon-bone healing after ACL reconstruction.
ObjectiveTo explore the effect of silk fibroin/poly(L-lactic acid-co-e-caprolactone) [SF/P(LLA-CL)] nanofibrous scaffold on tendon-bone healing of rabbits.MethodsSF/P(LLA-CL) nanofibrous scaffold was fabricated by electrospinning methods. The morphology of the scaffold was observed by scanning electron microscope (SEM). Pre-osteoblasts MC3T3-E1 cells were seeded on the scaffold and cultured for 1, 3, and 5 days. Cell adhesion and proliferation were also observed by SEM. Meanwhile, twenty-four New Zealand white rabbits were randomly divided into the autogenous tendon group (control group) and the autogenous tendon wrapped with SF/P(LLA-CL) scaffold group (experimental group), with twelve rabbits in each group. An extra-articular model was established, the effect was evaluated by histological examination and mechanical testing.ResultsThe morphology of SF/P(LLA-CL) nanofibrous scaffold was random, with a diameter of (219.4±66.5) nm. SEM showed that the MC3T3-E1 cells seeded on the scaffold were in the normal shape, growing well, and proliferating with time course. The results of histological examination showed that inflammatory cells infltrated into the graft-host bone interface at 6 weeks after operation in both groups. Besides, the width of interface showed no significant difference between groups. At 12 weeks after operation, protruding new bone tissue could be observed at the interface in the experimental group, while scar tissue but no new bone tissue could be seen at the interface in the control group. Mechanical testing showed that there was no significant difference in the failure load and the stiffness between groups at 6 weeks after operation (P>0.05). The failure load and the stiffness in the experimental group were significantly higher than those in the control group at 12 weeks after operation (P<0.05).ConclusionThe SF/P(LLA-CL) nanofibrous scaffold has good cell biocompatibility and can effectively promote tendon-bone healing, thus providing new method for modifying graft for ACL reconstruction in the clinical practice.
ObjectiveTo assess the effect of microfracture and biomimetic hydrogel scaffold on tendon-to-bone healing in a rabbit rotator cuff tear model.MethodsGelatin and methacrylic anhydride were used to synthesize gelatin methacryloyl (GelMA). Then the GelMA were treated with ultraviolet rays and vacuum freeze-drying method to obtain a biomimetic hydrogel scaffold. The morphology of the scaffold was observed by gross observation and scanning electron microscope. Degradation of the scaffold was determined at different time points. Twenty-four adult New Zealand rabbits, weighting 2.8-3.5 kg and male or female, were surgically created the bilateral acute rotator cuff tear models. One shoulder was treated with microfractures on the footprint and transosseous suture (control group, n=24). The other shoulder was treated with the same way, except for putting the scaffold on the footprint before transosseous suture (experimental group, n=24). The general conditions of rabbits were observed postoperatively. Tendon-to-bone healing was evaluated by gross observation, Micro-CT, HE staining, and bio-mechanical testing at 4 and 8 weeks after operation.ResultsThe scaffold was white and has a porous structure with pore size of 31.7-89.9 μm, which degraded slowly in PBS solution. The degradation rate was about 95% at 18 days. All the rabbits survived to the completion of the experiment. Micro-CT showed that there was no obvious defect and re-tear at the tendon-to-bone interface in both groups. No difference was found in bone mineral density (BMD), tissue mineral density (TMD), and bone volume/total volume (BV/TV) between the two groups at 4 and 8 weeks postoperatively (P>0.05). HE staining showed that the fibrous scar tissue was the main component at the tendon-to-bone interface in the control group at 4 and 8 weeks postoperatively; the disorderly arranged mineralized cartilage and fibrocartilage formation were observed at the tendon-to-bone interface in the experimental group at 4 weeks, and the orderly arranged cartilage formation was observed at 8 weeks. Besides, the tendon maturation scores of the experimental group were significantly higher than those of the control group at 4 and 8 weeks (P<0.05). There was no significant difference in the ultimate load to failure and stiffness between the two groups at 4 weeks (P>0.05); the ultimate load to failure at 8 weeks was significantly higher in the experiment group than in the control group (t=4.162, P=0.009), and no significant difference was found in stiffness between the two groups at 8 weeks (t=2.286, P=0.071).ConclusionCompared with microfracture alone, microfracture combined with biomimetic hydrogel scaffold can enhance tendon-to-bone healing and improve the ultimate load to failure in rabbits.
ObjectiveTo investigate the effectiveness of percutaneous compression plate (PCCP) fixation for femoral neck fracture.MethodsA clinical data of 100 patients with femoral neck fractures who were treated with internal fixation were analyzed retrospectively. The fractures were fixed with the cannulated screws (CS) in 55 patients (CS group) and with the PCCP in 45 patients (PCCP group). There was no significant difference in gender, age, the cause of injury, the fracture type, complications, and disease duration between the two groups (P>0.05). The quality of fracture reduction, bone resorption, screw slipping, femoral neck shortening, complications (nonunion, failure of fixation, and osteonecrosis of femoral head), and functional recovery of hip (Harris score) were compared between the two groups.ResultsAll incisions healed by first intention. All patients were followed up 24-56 months, with an average of 30.7 months. The quality of fracture reduction was excellent in 26 cases, good in 18 cases, fair in 9 cases, and poor in 2 cases in CS group and excellent in 21 cases, good in 17 cases, fair in 4 cases, and poor in 3 cases in PCCP group, showing no significant difference between the two groups (Z=−0.283, P=0.773). The incidence of nonunion in PCCP group was significantly lower than that in CS group (P=0.046), and the fracture healing time in PCCP group was shorter than that in CS group (t=2.155, P=0.034). There was no significant difference in the incidences of bone resorption, screw slipping, femoral neck shortening, failure of fixation, and osteonecrosis of femoral head between the two groups (P>0.05). The overall complication rates were 27.27% (15/55) in CS group and 8.89% (4/45) in PCCP group, showing significant difference (χ2=5.435, P=0.020). The Harris score in PCCP group at 6 months after operation was significantly higher than that in CS group (t=−2.073, P=0.041). However, there was no significant difference in the Harris score at 12, 18, and 24 months after operation between the two groups (P>0.05).ConclusionStable sliding compression of PCCP is benefit for the femoral neck fracture healing, especially shortening union.
Parathyroid hormone (PTH) exerts multiple effects such as regulating bone remodeling, promoting angiogenesis, etc., and it is an active factor with great application potential for bone repair. In recent years, with the development of scaffold material loading strategies and parathyroid hormone-related peptides (PTHrPs), in situ loading of PTH or PTHrPs on scaffold materials to promote bone defect healing gradually becomes possible. Based on the current status and challenges of intermittent PTH (iPTH) for bone tissue engineering, the review summarizes the in-situ application strategies of PTH and the construction of PTHrPs as well as current problems and further directions in this field, with a view to propel the clinical application of scaffold materials loaded with PTH or PTHrPs in situ.