Enhanced zone II flexor tendon repair through a new half hitch loop suture configuration

This study evaluated the impact of a new half hitch loop suture configuration on flexor tendon repair mechanics. Cadaver canine flexor digitorum profundus tendons were repaired with 4- or 8-strands, 4-0 or 3-0 suture, with and without half hitch loops. An additional group underwent repair with half hitch loops but without the terminal knot. Half hitch loops improved the strength of 8-strand repairs by 21% when 4-0, and 33% when 3-0 suture was used, and caused a shift in failure mode from suture pullout to suture breakage. 8-strand repairs with half hitch loops but without a terminal knot produced equivalent mechanical properties to those without half hitch loops but with a terminal knot. 4-strand repairs were limited by the strength of the suture in all groups and, as a result, the presence of half hitch loops did not alter the mechanical properties. Overall, half hitch loops improved repair mechanics, allowing failure strength to reach the full capability of suture strength. Improving the mechanical properties of flexor tendon repair with half hitch loops has the potential to reduce the postoperative risk of gap formation and catastrophic rupture in the early postoperative period

The effect of mesenchymal stromal cell sheets on the inflammatory stage of flexor tendon healing

BACKGROUND: The clinical outcomes following intrasynovial flexor tendon repair are highly variable. Excessive inflammation is a principal factor underlying the formation of adhesions at the repair surface and affecting matrix regeneration at the repair center that limit tendon excursion and impair tendon healing. A previous in-vitro study revealed that adipose-derived mesenchymal stromal cells (ASCs) modulate tendon fibroblast response to macrophage-induced inflammation. The goal of the current study was therefore to explore the effectiveness of autologous ASCs on the inflammatory stage of intrasynovial tendon healing in vivo using a clinically relevant animal model. METHODS: Zone II flexor tendon transections and suture repairs were performed in a canine model. Autologous ASC sheets were delivered to the surface of repaired tendons. Seven days after repair, the effects of ASCs on tendon healing, with a focus on the inflammatory response, were evaluated using gene expression assays, immunostaining, and histological assessments. RESULTS: ASCs delivered via the cell sheet infiltrated the host tendon, including the repair surface and the space between the tendon ends, as viewed histologically by tracking GFP-expressing ASCs. Gene expression results demonstrated that ASCs promoted a regenerative/anti-inflammatory M2 macrophage phenotype and regulated tendon matrix remodeling. Specifically, there were significant increases in M2-stimulator (IL-4), marker (CD163 and MRC1), and effector (VEGF) gene expression in ASC-sheet treated tendons compared with nontreated tendons. When examining changes in extracellular matrix expression, tendon injury caused a significant increase in scar-associated COL3A1 expression and reductions in COL2A1 and ACAN expression. The ASC treatment effectively counteracted these changes, returning the expression levels of these genes closer to normal. Immunostaining further confirmed that ASC treatment increased CD163(+) M2 cells in the repaired tendons and suppressed cell apoptosis at the repair site. CONCLUSIONS: This study provides a novel approach for delivering ASCs with outcomes indicating potential for substantial modulation of the inflammatory environment and enhancement of tendon healing after flexor tendon repair

Σύγκριση χρήσης νευραγωγών σιλικόνης με ή χωρίς τη χρήση T3 και BDNF ως εναλλακτική μέθοδο των αυτομοσχευμάτων για την γεφύρωση νευρικών ελλειμμάτων σε αρουραίους

Η μικροχειρουργική και η βιολογική μηχανική των ιστών είναι σημαντικά εργαλεία για την βελτίωση των λειτουργικών αποτελεσμάτων στην χειρουργική αποκατάσταση των νευρικών ελλειμμάτων. Στο συγκεκριμένο πρωτόκολλο μελετήθηκε η δράση της τοπικής και μονοδοσικής χορήγησης Τ3 και BDNF εντός νευρικού αγωγού σιλικόνης στην γεφύρωση ενός νευρικού ελλείμματος 10 mm στο ισχιακό νεύρο αρουραίων. Τα αποτελέσματα συγκρίθηκαν με την κλασσική τεχνική γεφύρωσης νευρικών ελλειμμάτων που είναι η χρήση αυτομοσχευμάτων.Microsurgery and tissue engineering are crucial to improving the outcomes of bridging peripheral nerve gaps. This protocol was employed to study the effect of a single and local administration of T3 and BDNF into silicone conduit on bridging a 10 mm sciatic nerve gap in rats. The results were compared with those of the gold standard technique of autografting

A comparison of silicone nerve conduits with or without using T3 and BDNF as an autografting alternative for bridging nerve gaps in rats

Microsurgery and tissue engineering are crucial to improving the outcomes of bridging peripheral nerve gaps. This protocol was employed to study the effect of a single and local administration of T3 and BDNF into silicone conduit on bridging a 10 mm sciatic nerve gap in rats. The results were compared with those of the gold standard technique of autografting.Η μικροχειρουργική και η βιολογική μηχανική των ιστών είναι σημαντικά εργαλεία για την βελτίωση των λειτουργικών αποτελεσμάτων στην χειρουργική αποκατάσταση των νευρικών ελλειμμάτων. Στο συγκεκριμένο πρωτόκολλο μελετήθηκε η δράση της τοπικής και μονοδοσικής χορήγησης Τ3 και BDNF εντός νευρικού αγωγού σιλικόνης στην γεφύρωση ενός νευρικού ελλείμματος 10 mm στο ισχιακό νεύρο αρουραίων. Τα αποτελέσματα συγκρίθηκαν με την κλασσική τεχνική γεφύρωσης νευρικών ελλειμμάτων που είναι η χρήση αυτομοσχευμάτων

Suture configuration.

<p><b>(A-C)</b> The three suture passes required to make a single half hitch loop are shown sequentially as an end view from the transection interface, a side view, and a perspective view. This is a continuous piece of suture, where suture coloration is artificially added to aid in following the suture path, going from blue to purple. The suture diameter is enlarged two-fold for clarity. Looped suture is used surgically, but only one of each pair of suture threads is diagrammed here for simplicity. <b>(D)</b> The complete half hitch loop configuration is enlarged for clarity. <b>(E-F)</b> The locations of half hitch loops are shown in green for 4-strand modified Kessler (E) and 8-strand Winters-Gelberman (F) repairs. In 8-strand repairs, the first four passes were performed on the dorsal side and the last four passes were performed on the ventral side of the tendon.</p

Mechanical properties of repairs (mean ± standard deviation).

<p>Mechanical properties of repairs (mean ± standard deviation).</p

Failure modes.

<p>Repairs completed with 4–0 caliber suture failed almost exclusively by suture breakage. Increasing suture caliber from 4–0 to 3–0 led to a shift in failure mode from suture breakage to suture pullout. The addition of half hitch loops shifted the failure mode in 3–0 suture caliber repairs back to suture breakage, indicating a significant increase in suture-tendon interaction due to the hitches. (G: grasping, H: hitched, K: hitched knotless).</p

Shear Lag Sutures: Improved Suture Repair through the Use of Adhesives

Conventional surgical suture is mechanically limited by the ability of the suture to transfer load to tissue at suture anchor points. Sutures coated with adhesives can improve mechanical load transfer beyond the range of performance of existing suture methods, thereby strengthening orthopaedic repairs and decreasing the risk of failure. The mechanical properties of suitable adhesives were identified using a shear lag model. Examination of the design space for an optimal adhesive demonstrated requirements for strong adhesion and low stiffness to maximize strength. As a proof of concept, cyanoacrylate-coated sutures were used to perform a clinically relevant flexor digitorum profundus tendon repair in cadaver tissue. Even with this non-ideal adhesive, the maximum load resisted by repaired cadaveric canine flexor tendon increased by ∼ 17.0% compared to standard repairs without adhesive. To rapidly assess adhesive binding to tendon, we additionally developed a lap shear test method using bovine deep digital flexor tendons as the adherends. Further study is needed to develop a strongly adherent, compliant adhesive within the optimal design space described by the model