Complications in Canine Cranial Cruciate Ligament Surgery. Ron Ben-Amotz

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2 Surgeon and Patient Preparation to Minimize Surgical Site Complications and Infection Surveillance Programs

      Katie L. Hoddinott, J. Scott Weese, and Ameet Singh

2.1 Introduction

The reported incidence of surgical site infections (SSIs) in companion animal veterinary medicine ranges from 3% to 18.1%, with increasing risk of SSI development associated with increasing classification of the surgical procedure (Table 2.1) [1–7]. Orthopedic surgeries are most commonly classified as clean procedures; however, SSI rates are often higher in clean orthopedic surgeries (3.54–12.9%) when compared to other clean surgical procedures (2.5–4.8%) [5,7–9]. Furthermore, SSI rates vary amongst surgical stabilization techniques for treatment of cranial cruciate ligament ruptures. Extracapsular repair techniques, including the lateral fabellotibial suture and Arthrex Canine Cruciate Ligament Repair Anchor System™, have reported SSI rates ranging from 3.9% to 21% [6,10–12] while proximal tibial osteotomy procedures, including tibial plateau leveling osteotomy (TPLO), tibial tuberosity advancement (TTA), triple tibial osteotomy, and cranial closing wedge osteotomies, have reported SSI rates ranging from 4.7% to 25.9% [13–26].

Many risk factors have been associated with development of SSIs following surgical stabilization of the cranial cruciate‐deficient stifle. These risk factors may be associated with the host, the environment, details surrounding the surgical procedure and the use of antimicrobials. Host factors include breed, sex, body weight, American Society of Anesthesiologists (ASA) status, methicillin‐resistant Staphylococcus pseudintermedius (MRSP) carrier status, and skin microbiome. Environmental factors include the number of personnel in the surgical suite and potential for bacterial contamination from surrounding surfaces. Surgical procedure factors include the method of stifle stabilization, length of general anesthesia, length of surgical procedure, surgeon preparation, intraoperative contamination, adherence to Halstead's principles (Table 2.2), and choice of implant and wound closure materials. Finally, the use of antimicrobials in the preoperative, perioperative, and postoperative periods has been documented as a risk factor for SSI.

2.2 Host Factors

      2.2.1 Breed, Sex, and Body Weight

Several host factors identified as risk factors for SSI development are beyond the control of the veterinary team, such as breed, sex, and body weight. Bulldogs and German Shepherds have been identified as having an increased risk for development of SSI following TPLO surgery [21, 27]. Labrador Retrievers and mixed‐breed dogs have been identified as having a lower SSI development risk following TPLO surgery [4, 3]. Both Fitzpatrick and Solano and Nicholson et al. identified intact male dogs to be at higher risk of SSI; however, sex was not identified as a risk factor in other studies [3, 4, 17, 28]. Increased body weight has been significantly associated with an increased SSI risk in several studies [2, 4, 10, 15,28–30]. In one study, each 1 kg increase in body weight resulted in 1.03 times increased odds of developing an SSI, while a second study noted that for each 1 kg increase in body weight, the odds of developing an SSI increased by 4.7% [28, 29]. As these factors are inherent to the patient and cannot be specifically controlled, this information can be utilized to distinguish those animals at higher risk of developing an SSI and thus requiring greater preventive measures.

Table 2.1 Surgical procedure classification.

      Source: Based on Turk et al. [1], Eugster et al. [2], Nicholson et al. [3], Fitzpatrick and Solano [4], Beal et al. [5], Frey et al. [6], and Vasseur et al. [7].

Clean	No infection No break in aseptic technique Nontraumatic
Clean‐contaminated	Controlled access to a hollow viscus Minor break in aseptic technique
Contaminated	Entry through nonseptic, yet inflamed tissues Spillage from a hollow viscus – localized, controlled Major break in aseptic technique Fresh, traumatic wounds (<4 h)
Dirty	Perforated hollow viscus Septic purulent discharge encountered Chronic, traumatic wounds (>4 h)

Table 2.2 Halstead's principles.

Gentle tissue handling Meticulous hemostasis Strict aseptic technique Preservation of blood supply Elimination of dead space Accurate apposition of tissues while minimizing tension

      2.2.2 ASA Status and Endocrinopathies

Preoperative ASA score (Table 2.3) has been correlated with risk for developing an SSI, such that the risk for SSI increases with each increment in ASA score [2]. As ASA scores take into consideration the overall health status of a patient, the higher the ASA score, the more systemically ill the patient. Animals with endocrinopathies have also been identified to be 8.2 times more likely to develop an SSI, likely due to alterations in immune function [3]. Logically, if an animal has a chronic illness, such as an unmanaged or poorly controlled endocrinopathy, postponement of elective orthopedic procedures until these illnesses