Effect of Platelet-Rich Plasma at Different Initiation Times on Healing of the Bone-Tendon Interface of the Rotator Cuff in a Mouse Model.

Background: Platelet-rich plasma (PRP) has demonstrated beneficial effects on healing of the bone-tendon interface (BTI). Purpose: To determine the optimal initiation time for PRP application after rotator cuff repair in an animal model. Study Design: Controlled laboratory study. Methods: A total of 136 C57BL/6 mice were included; 40 mice were used to prepare PRP, while 96 mice underwent acute supraspinatus tendon (SST) repair. The animals were randomly divided into 4 groups: a control group and 3 groups in which PRP was injected into the injury interface immediately after surgery, on the 7th postoperative day (PRP-7d), and on the 14th postoperative day. At 4 and 8 weeks postoperatively, the animals were sacrificed, blood was collected by eyeball removal, and samples of the SST-humerus complex were collected. Histological, imaging, immunological, and biomechanical data were compared among the groups using 1-way analysis of variance with the Bonferroni post hoc test. Results: Histological analysis revealed that the fibrocartilage layer at the BTI was larger in the PRP-7d group compared to the other groups at both 4 and 8 weeks postoperatively. Moreover, the PRP-7d group exhibited improved proteoglycan content and distribution compared to the other groups. Enzyme-linked immunosorbent assay results demonstrated that at 4 weeks postoperatively, higher concentrations of transforming growth factor-ß1 and platelet-derived growth factor-BB (PDGF-BB) were seen in the PRP-7d group versus the PRP-14d and control gruops (P < .05), and at 8 weeks postoperatively, the concentration of PDGF-BB was higher in the PRP-7d group versus the control group (P < .05). Biomechanical testing at 4 weeks postoperatively revealed that the failure load and ultimate strength of the SST-humerus complex were superior in the PRP-7d group compared to the other groups (P < .05), at 8 weeks, PRP-7d group was superior to the control group (P < .05). Additionally, at 8 weeks postoperatively, the PRP-7d group exhibited a greater trabecular number and trabecular thickness at the BTI compared to the PRP-14d and control gruops (P < .05). Conclusion: PRP promoted healing of the BTI after a rotator cuff injury at an early stage. Clinical Relevance: A PRP injection on the 7th postoperative day demonstrated superior therapeutic effects compared with injections at other time points.

Effects of adipose-derived cell supplementation on tendon-bone healing in a rat model of chronic rotator cuff tear with suprascapular nerve injury.

OBJECTIVE: To investigate the effect of adipose-derived cells (ADCs) on tendon-bone healing in a rat model of chronic rotator cuff tear (RCT) with suprascapular nerve (SN) injury. METHODS: Adult rats underwent right shoulder surgery whereby the supraspinatus was detached, and SN injury was induced. ADCs were cultured from the animals' abdominal fat. At 6 weeks post-surgery, the animals underwent surgical tendon repair; the ADC (+ve) group (n = 18) received an ADC injection, and the ADC (-ve) group (n = 18) received a saline injection. Shoulders were harvested at 10, 14, and 18 weeks and underwent histological, fluorescent, and biomechanical analyses. RESULTS: In the ADC (+ve) group, a firm enthesis, including dense mature fibrocartilage and well-aligned cells, were observed in the bone-tendon junction and fatty infiltration was less than in the ADC (-ve) group. Mean maximum stress and linear stiffness was greater in the ADC (+ve) compared with the ADC (-ve) group at 18 weeks. CONCLUSION: ADC supplementation showed a positive effect on tendon-bone healing in a rat model of chronic RCT with accompanying SN injury. Therefore, ADC injection may possibly accelerate recovery in massive RCT injuries.

Hot spots and frontiers in bone-tendon interface research: a bibliometric analysis and visualization from 2000 to 2023.

Objective: In this research, we investigated the current status, hotspots, frontiers, and trends of research in the field of bone-tendon interface (BTI) from 2000 to 2023, based on bibliometrics and visualization and analysis in CiteSpace, VOSviewer, and a bibliometric package in R software. Methods: We collected and organized the papers in the Web of Science core collection (WoSCC) for the past 23 years (2000-2023), and extracted and analyzed the papers related to BTI. The extracted papers were bibliometrically analyzed using CiteSpace for overall publication trends, authors, countries/regions, journals, keywords, research hotspots, and frontiers. Results: A total of 1,995 papers met the inclusion criteria. The number of papers published and the number of citations in the field of BTI have continued to grow steadily over the past 23 years. In terms of research contribution, the United States leads in terms of the number and quality of publications, number of citations, and collaborations with other countries, while the United Kingdom and the Netherlands lead in terms of the average number of citations. The University of Leeds publishes the largest number of papers, and among the institutions hosting the 100 most cited papers Hospital for Special Surgery takes the top spot. MCGONAGLE D has published the highest number of papers (73) in the last 10 years. The top three clusters include #0 "psoriatic arthritis", #1 "rotator cuff repair", and #2 "tissue engineering". The structure and function of the BTI and its key mechanisms in the healing process are the key to research, while new therapies such as mechanical stimulation, platelet-rich plasma, mesenchymal stem cells, and biological scaffolds are hot topics and trends in research. Conclusion: Over the past 23 years, global research on the BTI has expanded in both breadth and depth. The focus of research has shifted from studies concentrating on the structure of the BTI and the disease itself to new therapies such as biomaterial-based alternative treatments, mechanical stimulation, platelet-rich plasma, etc.