An Experimental Study on the Effect of Safflower Yellow on Tendon Injury-Repair in Chickens

Current trends in the prevention of adhesions after zone 2 flexor tendon repair

Treating flexor tendon injuries within the digital flexor sheath (commonly referred to as palmar hand zone 2) presents both technical and logistical challenges. Success hinges on striking a delicate balance between safeguarding the surgical repair for tendon healing and initiating early rehabilitation to mitigate the formation of tendon adhesions. Adhesions between tendon slips and between tendons and the flexor sheath impede tendon movement, leading to postoperative stiffness and functional impairment. While current approaches to flexor tendon repair prioritize maximizing tendon strength for early mobilization and adhesion prevention, factors such as pain, swelling, and patient compliance may impede postoperative rehabilitation efforts. Moreover, premature mobilization could risk repair failure, necessitating additional surgical interventions. Pharmacological agents offer a potential avenue for minimizing inflammation and reducing adhesion formation while still promoting normal tendon healing. Although some systemic and local agents have shown promising results in animal studies, their clinical efficacy remains uncertain. Limitations in these studies include the relevance of chosen animal models to human populations and the adequacy of tools and measurement techniques in accurately assessing the impact of adhesions. This article provides an overview of the clinical challenges associated with flexor tendon injuries, discusses current on- and off-label agents aimed at minimizing adhesion formation, and examines investigational models designed to study adhesion reduction after intra-synovial flexor tendon repair. Understanding the clinical problem and experimental models may serve as a catalyst for future research aimed at addressing intra-synovial tendon adhesions following zone 2 flexor tendon repair.

Acmella oleracea extract increases collagen content and organization in partially transected tendons

Acmella oleracea contains spilanthol as the main active compound, which possesses analgesic and anti-inflammatory effects that can favor tendon reorganization. To analyze the effect of A. oleracea on the content and organization of collagen in injured tendons, the calcaneal tendon of male Lewis rats was partially transected and treated at the site of injury with a topical application of 20% A. oleracea ointment (AO group) or with the ointment base without the plant extract (B group). The animals were euthanized 21 days after partial transection. Higher collagen concentration was observed in the AO group than in the B group, and morphological analysis using polarization microscopy showed higher birefringence in the AO group than in the B group, indicating higher collagen organization. No difference was observed in the number of fibroblasts, blood vessels, proteoglycan distribution, and maximum load between the B and AO groups. In conclusion, topical application of 20% A. oleracea ointment increased the molecular organization and content of collagen, thus indicating a potential application in tendon repair. Studies on the later phases of the tendon healing process are necessary to demonstrate the possible biomechanical changes after the application of A. oleracea ointment.

Prospective application of stem cells to prevent post-operative skeletal fibrosis

Post-operative skeletal fibrosis is considered one of the major complications causing dysfunction of the skeletal system and compromising the outcomes of clinical treatment. Limited success has been achieved using current therapies; more effective therapies to reduce post-operative skeletal fibrosis are needed. Stem cells possess the ability to repair and regenerate damaged tissue. Numerous studies show that stem cells serve as a promising therapeutic approach for fibrotic diseases in tissues other than the skeletal system by inhibiting the inflammatory response and secreting favorable cytokines through activating specific signaling pathways, acting as so-called medicinal signaling cells. In this review, current therapies are summarized for post-operative skeletal fibrosis. Given that stem cells are used as a promising therapeutic approach for fibrotic diseases, little effort has been undertaken to use stem cells to prevent post-operative skeletal fibrosis. This review aims at providing useful information for the potential application of stem cells in preventing post-operative skeletal fibrosis in the near future. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1236-1245, 2019.

Molecular Biology of Flexor Tendon Healing in Relation to Reduction of Tendon Adhesions

Tendon injuries are encountered after major and minor hand trauma. Despite meticulous repair technique, adhesion formation can occur, limiting recovery. Although a great deal of progress has been made toward understanding the mechanism of tendon healing and adhesions, clinically applicable solutions to prevent adhesions remain elusive. The goal of this paper is to review the most recent literature relating to the tendon healing and adhesion prevention.

Phytochemistry and Pharmacology of Carthamus tinctorius L

Carthamus tinctorius L. is a multifunctional cash crop. Its flowers and seeds are extensively used in traditional herbal medicine in China, Korea, Japan, and other Asian countries, for treating various ailments such as gynecological, cardiovascular, and cerebrovascular diseases as well as blood stasis and osteoporosis. More than 100 compounds have been isolated and identified from C. tinctorius. Flavonoids and alkaloids, especially the quinochalcone c-glycoside hydroxysafflor yellow A, N-(p-Coumaroyl)serotonin, and N-feruloylserotonin, are responsible for most of the pharmacological activities of C. tinctorius. In this paper, comprehensive and up-to-date information on the phytochemistry and pharmacology of C. tinctorius is presented. This information will be helpful for further explorations of the therapeutic potential of C. tinctorius and may provide future research opportunities.

History and performance of implant materials applied as peritendinous antiadhesives

Peritendinous fibrotic adhesions after tendon surgery are still a problem up-to-date. Approaches to overcome or at least minimize adhesion formation include implantation of barrier materials, application of lubricants or combinations of materials and functionalized drugs that are controllably released and support the healing tendon to glide and achieve the full range of motion after regeneration. Although a huge amount of different materials have been experimentally tested, the optimal strategy with respect to material and method has not yet been determined. In this review, we present a historical overview of physical barriers as well as liquid agents that have been used in order to prevent peritendinous adhesion formation. The materials are divided according to their first publication into two time frames; before and after 1980. There is no claim to include all materials tested neither will the "best" material be chosen; however, we present several materials that were experimentally tested in different animal trials as well as in clinical trials in contrast to other materials that were only tested once and disappeared from the assortment of anti-adhesives; which as such is a valuable information about its applicability for this purpose.

Does loading velocity affect failure strength after tendon repair?

Tensile testing of repaired tendons has been used to assess the efficacy of repair techniques. However, individuals flex and extend fingers at rates higher than those typically used for testing. This study characterized the effect of loading rate on the failure strength of repaired canine flexor tendons. Thirty-six canine flexor digitorum profundus tendons were lacerated, repaired, and tested at three displacement rates: 0.33 mm/s; 84 mm/s; and 590 mm/s. Peak force and stiffness of the repairs were evaluated. Peak force was significantly greater (p<0.05) for tendons distracted at 590 mm/s than at 0.33 mm/s. Crosshead stiffness was significantly greater for tendons distracted at 590 mm/s than at either 84 mm/s or 0.33 mm/s. The predominant failure mode was core suture knot untying. Distracting tendons at slow loading rates provides a conservative assessment of tendon repair strength. Additionally, an estimate of the failure load of this repair for different clinical events has been identified.