Complications in Equine Surgery. Группа авторов

sutures such as polyglycolic acid and polyglactin 910, cause a mild inflammatory response characterized by the presence of macrophages and fibroblasts at the wound site [23, 24]. Alternatively, synthetic nonabsorbable sutures such as nylon and polypropylene are biologically inert and cause minimal tissue reaction [23, 24]. Steel is biologically inert and incites no inflammatory reaction, except for that caused by inflexible suture ends [23, 24].

       Inappropriately large suture

      Using larger suture size than necessary results in unnecessary foreign material present within the wound/incision, altering the tissue structure, causing excessive tissue reaction, weakening the incision line and therefore decreasing the capacity to resist infection [3, 9]. Knot size depends on suture size and number of throws. Suture size is the principle influence on knot volume and tissue reactivity; an increase in suture size increases tissue reaction more than adding an extra throw to a knot [22].

       Excessive suture material

      Suture material acts as a foreign body and induces a tissue reaction in the incisional line [25]. Inflammatory reactions to sutures are most pronounced close to the knots because they have the largest amount of foreign material [22].

       Inappropriate suture technique

      The suturing technique and excessive and inappropriate handling of the tissues and unnecessary needle sticks will increase tissue inflammation and edema formation [23].

      Excessive tension can affect the local blood flow and increase the inflammatory response resulting in tissue ischemia and pressure necrosis [3, 7].

       Prevention

      Appropriate surgical knowledge and technique for the given suture(s) location is crucial in limiting the occurrence of tissue reactions to sutures. Physical and biological characteristics of suture materials should be considered when selecting a suture material and size [5, 9]. Even the least reactive suture materials act as foreign material, thus minimizing the amount of suture material within the tissues without compromising the closure should be the objective in incisional closures [9]. Therefore, decreasing the amount of suture material within the tissues is achieved by minimizing the number of sutures, using the smallest adequate suture size, having the fewest number of knots achievable, keeping the number of throws in a knot to a minimum, avoiding a surgeon's throw when possible, and not having excessively long suture tails [3, 9, 23]. Suture absorption time and the gain in wound strength of the sutured tissues over time should coincide [2, 3]. Monofilament suture material is recommended instead of multifilament if the circumstances allow [23].

       Diagnosis

      Tissue reaction to suture material is usually diagnosed with observation of tissue edema or swelling filled with clear fluid around an individual suture or entire suture line [23]. Erythema in light‐colored skin or heat and pain to palpation are other clinical signs that can assist in the diagnosis of tissue suture reaction. There may also be present a draining tract to the skin if the suture reaction is of deeper tissues [23]. Ultrasound is not usually needed for the diagnosis but can be useful in identifying problematic suture fragments or segments. Suture reactions can also result in other observed incisional complications including infection, wound disruption, and chronic sinus formation and it can be difficult to determine whether tissue suture reaction or suture line infection were the initiating causes that disrupted wound healing.

       Treatment

      Treatment of tissue reactions to suture will vary, depending on the degree of clinical signs. If the suture reaction is mild, then typically no treatments are required. For more advanced suture reactions or if the reaction does not resolve within 1–2 weeks, then removal of the suture(s) or entire suture line is indicated. [23]. Samples of the affected tissues should then be submitted for bacterial culture and histopathological assessment [23]. Once the problematic sutures have been removed, the wound can be closed with a more inert suture material or left to heal by second intention, depending on the circumstances of the case. Granulomatous or abscess formation, and suture sinuses will usually heal without detrimental complication once the inciting suture is removed [9].

       Expected outcome

Tissue suture reactions can result in increased morbidity to the patient, prolonged wound healing time, decreased cosmetic appearance of the surgical site, and an increase in the treatment costs. However, the prognosis is usually good after removal of the problematic suture(s) [9, 23].

Ligature Loop Failure

       Definition

      Ligation suture loops are commonly used for hemostasis of an isolated vessel, vascular pedicle, or other structure and have the potential to fail via suture slippage or suture breaking.

       Risk factors

       Suture material

       Suture size

       Inappropriate ligation knotting

       Inappropriate ligation placement

       Tissue bulk

       Pathogenesis

      Suture material, ligation technique, number of ligatures, and manipulation of the vessel or pedicle are all factors that should be considered when performing a ligation [26]. Ligation knot slippage or breakage is a significant contributor to ligation failure and occurrence is likely underestimated [27].

       Suture material

      The use of multifilament suture for laparoscopic ligating loops does not maintain the shape of the loop well due to low stiffness of the suture material and may result in inadequate placement of the ligating loop [28, 29].

       Suture size

      Selection of suture that is too small will result in suture loop breakage, typically at the knot where suture tension forces have been converted to shear forces, making the knot the weakest point of the suture loop [9].

       Inappropriate ligation knotting

      The square knot is used commonly for vessel ligation but, however, performs poorly when compared to a slip knot, modified transfixing ligature, or single‐double other side knot [26]. When using a square knot, it is dependent on there being no slippage of the first throw until the second throw has secured the knot [26]. Every knot type is at risk of not providing appropriate vessel occlusion and hemostasis if the surgical technique is not sufficient.

       Inappropriate ligation placement

      Transection of the vessel/pedicle too close to the ligature can result in ligature slippage [29].

       Tissue bulk

      Tissue bulk of a pedicle or tissue surrounding a vessel can inhibit the ability to achieve adequate occlusion of the vessel and result in hemorrhage.

       Prevention

      The importance of meticulous and proper placement of ligatures is essential for healing and preventing surgical complications. Whether it is open surgery or laparoscopy, ligatures are placed for the same reasons; however, there may be differences in the mechanics of the