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Category: Basic Sciences/Biologics; Ankle Introduction/Purpose: Achilles tendon defects are a challenging problem, and there is a need for new treatments. We investigated the use of Platelet-rich fibrin (PRF), a dense fibrin scaffold containing many growth factors and cytokines, for Achilles tendon injuries. The study found that PRF accelerates healing by promoting the proliferation and activation of tenocytes via FGF receptor/AKT signaling and TGF-β/SMAD3 signaling. While FGF-2, a growth factor in PRF, has been shown to promote tenocyte differentiation and proliferation, its effect on Achilles tendon injuries has not been reported. Therefore, this study aimed to investigate the effect of FGF-2 on Achilles tendon healing when administered alone and to determine its specific contribution to the healing process. Methods: We used a rat model of Achilles tendon defect. A 4-mm portion of the right Achilles tendon, 4 mm proximal to the calcaneal insertion, was resected to create a tendon defect. Gelatin hydrogel sheet (MedGel PI5) as a scaffold for PBS, FGF-2 (Rigroth®), and FGF receptor inhibitor (FGFRI: Pemigatinib) was placed into the gap before suturing it with nylon sutures. We observed HE-stained specimens at 200x and assessed histological healing by counting cells and vessels and grading cell morphology. The motor function was evaluated by the Basso, Beattie, and Bresnahan (BBB) score and the treadmill test. We compared the effects of FGF-2 on tenocytes isolated from rat Achilles tendons in the control, FGF2, and FGFRI groups. The proliferation and migration of tenocytes were measured by MTS assay and wound closure assay, respectively. Protein expression, such as Tenomodulin (Tnmd), Collagen Ⅰ, Ⅲ, and Screlaxis-A in cells, were evaluated by Western Blotting. Results: In the rat model, the number of cells, vessels and cell morphology scores at the defect sites increased in the FGF-2 group and decreased in the FGFRI group at 2 and 4 weeks postoperatively. In the motor functional evaluation, the FGF-2 group showed earlier improvement in the BBB score and the treadmill test compared to the control and FGFRI groups. The MTS assay showed that the number of viable cells was higher in the FGF-2 group and lower in the FGFRI group than in the control. Wound closure assay showed tenocyte migration was increased in the FGF-2 group and decreased in the FGFRI group. Regarding protein expression, Tnmd, Collagen I, III, and Screlaxis-A were increased in the FGF-2 group and decreased in the FGFRI group. Conclusion: In vivo, FGF-2 promoted healing of Achilles tendon injury, and FGFRI impeded it in terms of motor function and histology. Additionally, in vitro, FGF-2 promoted the proliferation and migration of tenocytes and enhanced extracellular matrix production, while FGFRI diminished these effects. Although native FGF-2 is produced at the injured site, further administration of FGF-2 accelerated Achilles tendon injury healing, while inhibiting the FGF receptor delayed recovery in this study. Therefore, FGF- 2 is very important in Achilles tendon injury healing and may promote recovery by enhancing angiogenesis, proliferation, and extracellular matrix production of tenocytes. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Sports Introduction/Purpose: The occurrence of peroneal tendon dislocation (PTD) may be influenced by anatomical variations in the peroneal muscles and ankle lateral malleolus. One such factor is peroneal groove crowding, which can result from increased muscle and tendons bulk within the peroneal tendon sheath. Another potential factor is the shape of the retromalleolar groove, which determines the inherent stability of the tendons in the groove. This study aims to examine the anatomical variations of the retromalleolar groove and peroneal muscles in patients with and without recurrent PTD (RPTD) using magnetic resonance imaging (MRI) and computed tomography (CT). Methods: This study included 30 patients (30 ankles) with recurrent PTD who underwent both MRI and CT before surgery (PD group) and 30 age- and sex-matched patients (control (CN) group) who underwent MRI and CT. The imaging was reviewed at the level of the tibial plafond (TP level) and the center slice between the TP and the fibula tip (CS level). CT images were used to assess the appearance of a malleolar groove (convex, concave, or flat) and the posterior tilting angle of the fibula. MRI images were used to assess the appearance of accessory peroneal muscles, height of the peroneus brevis muscle belly, and volume of the peroneal muscle and tendons. Low-lying muscle belly (LLMB) of the PB was defined as when the musculotendinous junction extended beyond the tip. The Mann-Whitney U test was used to compare continuous variables, and Fisher's exact test was used to compare nominal variables. Results: There were no differences in the appearance of the malleolar groove, posterior tilting angle of the fibula, or accessory peroneal muscles at the TP and CS levels between the PD and CN groups. However, the peroneal muscle ratio was significantly higher in the PD group than in the CN group at both levels (both p< 0.001). The peroneal tendons ratio was not significantly different between the groups at both levels. The height of the peroneus brevis muscle belly was significantly lower in the PD group than in the CN group (p=0.001). LLMB of the PB was identified in 19 patients (63.3%) in the PD group and in eight patients (26.7%) in the CN group (p=0.009). Conclusion: The findings of this study suggest that LLMB of the PB and the peroneal muscle ratio are significantly related to RPTD, whereas retromalleolar bony morphology is not. Therefore, maintaining proper volume in the peroneal tunnel is more important than the groove shape. Reduction of the muscle belly of the peroneus brevis during RPTD surgery may help prevent peroneal tendon dislocation. [ABSTRACT FROM AUTHOR]