Fig. 16.1
ACL infection; suggested management flow diagram
Once the diagnosis of postoperative septic arthritis has been made, prompt surgical management is critical in minimizing the deleterious effects on the articular proteoglycans and collagen by the bacterial production of degrading enzymes and toxins [40]. Second, in theory, any delay in treatment increases the risk of more complicated graft involvement and potential biofilm formation. For example, several authors have described debriding a “fibrinous coating” off of the graft [3, 12]. Also, with pathologic sectioning, bacteria have been found in the mid substance of the graft [15]. As a result, prompt administration of antibiotics and surgical irrigation and debridement remain the hallmarks of management in all cases. All suspected postoperative joint infections should be considered a surgical emergency and should be dealt with in an expedited fashion. A wait-and-see strategy has essentially no role in the treatment algorithm.
Antibiotics
Once cultures have been obtained, intravenous antibiotics should be administered as soon as possible. Empiric coverage should target the most likely organisms and later be tailored based on particular isolates and antibiotic sensitivities. Due to an increasing amount of antibiotic resistant gram positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) [41, 42] the use of broad spectrum, intravenous antibiotic as the initial treatment is likely prudent. While waiting for culture results, we recommend broad spectrum coverage with an agent effective against MRSA (e.g. Vancomycin) as well as gram negative coverage (e.g. third generation Cephalosporin). Once definitive cultures are obtained, the antibiotic regimen is tailored accordingly. In culture negative cases, empiric regimen covering Staphylococcus and Streptococcus species as well as anaerobes is indicated (e.g. Ceftriaxone and Metronidazole). Early involvement of an infectious disease specialist is often helpful.
Even in the nonsurgical septic arthritis literature, no consensus or randomized control trials exist concerning the duration of antibiotic treatment [43]. As a result, the duration of antibiotics is tailored to the individual. Intravenous antibiotics are continued for 6 weeks. Patients with intra-articular sepsis after ACL reconstruction are considered to have contiguous osteomyelitis, hence the 6 week duration. Some authors have advocated the routine use of high dose intra-articular antibiotics after irrigation and debridement [10]. As there is no good evidence to suggest its efficacy and because of the potential, but unproven, deleterious effects on intra-articular structures, its routine use in practice is not recommended, but may be considered in the most recalcitrant cases.
Surgical management
Surgical intervention plays a critical role in controlling and eradicating postoperative septic arthritis. Some literature, particularly dated research from the nonsurgical literature, has suggested antibiotics alone or repeat aspirations may be as sufficient as surgery in controlling septic arthritis [44]. We would advocate, in general, that a more aggressive approach utilizing both surgical and medical interventions likely affords the joint cartilage the greatest chance of survival and is the safest and most prudent approach in the young, otherwise healthy population of patients with suspected joint infection after ACLR.
Superficial wound infection
In the situation where an isolated superficial wound infection is diagnosed and there is no evidence of deep infection, we recommend oral antibiotics and serial examinations. However, the diagnosis should be absolutely clear and no doubt should exist that an insidious deeper infection lurks. If the wound infection worsens or fails to improve quickly, early wound debridement should be considered. An extremely low threshold for knee irrigation and debridement exists at all times. Only one research paper has discussed superficial wound infections after ACLR in detail [4]. In their experience, oral antibiotics and wound care were successful in 100 % of cases. However, there are relatively frequent reports in the literature of post-ACLR septic arthritis that were preceded by a prior diagnosis of a superficial infection [9].
Acutely infected ACLR
The infected ACLR knee should be brought to the operative theatre as soon as possible—ideally within hours of the diagnosis. Either an open, arthroscopic, or combined approach should be used to perform a thorough synovectomy, debridement, and washout of the knee. All surgical wounds including the graft harvest site should be surgically opened, regardless of their appearance, in order to ensure as few potential sources of recalcitrant infection are left behind. There have been reports of as high as 86 % of patients having secondary extra-articular sites of infection concurrent with the septic arthritis [15]. Although a formal arthrotomy is rarely necessary, the use of postero-medial and/or posterolateral accessory portals can be valuable in ensuring an adequate debridement and synovectomy is performed.
Regarding graft removal or retention, most investigators recommend retention whenever possible [7]. The knee should be examined under anaesthetic intraoperatively. If the knee is grossly unstable to Lachman and pivot shift testing, the graft is incompetent and it should be removed along with all hardware. Similarly, if there is a significant delay (>48 h) between the clinical picture of septic arthritis and surgical management, there should be a consideration of graft removal. In the more likely scenario where the knee remains stable and the diagnosis and subsequent treatment is reasonably prompt, graft retention during the first surgical intervention is an acceptable option. Careful inspection of the graft followed by debridement of any fibrinous exudates is necessary to avoid ongoing and recalcitrant infection. Some authors have suggested the decision of graft retention or removal be based on the visual appearance of the graft intraoperatively [5]. This is a potentially dangerous practice, given the low case exposure and the subjective nature of visual graft inspection.
Copious amounts of normal saline (>9 L) should be used to irrigate the knee and soft tissue wounds. The value of antibiotic impregnated solutions or impregnated solutions such as soap, alcohol, or betadine are not conclusively known to have any particular value. In fact, although impregnated solutions may have a greater bacterial kill rate in vivo, their effects on soft tissue viability are of particular concern. Similarly, although occasionally utilized, the addition of a postoperative drain or continuous irrigation device lacks evidence. In fact, postoperative intra-articular drains may undesirably serve as a conduit for further infection. Therefore, in the acutely infected ACLR, after thorough debridement and irrigation with normal saline, the wounds should be closed primarily without a drain. The use of intra-articular deposition of high dose antibiotic beads has been described [10]. This approach has several potential draw-backs and should be avoided: the sterile exudate created may serve as a potential source of ongoing drainage from wounds thereby complicating the clinical picture, effluent from the bead’s dissolution is often of a gritty consistency and may lead to a “third-body” mechanism of cartilage erosion, and the effect of high concentrations of antibiotic on articular cartilage, although unknown, may be deleterious. Its use may play a more important role in recalcitrant setting, particularly with osteomyelitis.
Postoperative management
All patients who undergo an initial irrigation and debridement and are suspected of having a deep infection should be admitted to hospital. Admission helps facilitate intravenous administration of antibiotics, allows for guided physiotherapy, and most importantly allows the best opportunity for close monitoring for clinical regression. A protocol of protected weight bearing with a knee immobilizer when ambulatory until quadriceps function and proprioception return should be instituted. Early, physiotherapist-guided range of motion of the knee is encouraged in an attempt to avoid postoperative stiffness. Liberal use of intermittent ice packs or cooling sleeve is encouraged to reduce postoperative swelling and to aid in pain control. Because of the added surgical insult, it may be prudent to add thromboprophylaxis and place patients on subcutaneous heparin on the first day postoperatively, and continue until the patient is fully mobile or for a minimum of 21 days. Reports of DVT and PE after post-arthroscopic infection exist [16]. Laboratory monitoring with WBC, ESR, and CRP is performed regularly during the initial postoperative period. Clinical monitoring should be frequent and the threshold for repeat irrigation and debridement should be extremely low. To give the articular cartilage its best chance at survival, and avoid recalcitrant cases, patients should be taken back to the operative theatre at approximately 48 h for an additional irrigation and debridement in order to avoid ongoing infection. In cases where the clinical picture is particularly benign, one trip to the operating room may suffice. However, this is an area of controversy for which there is limited evidence in the literature for either approach.
Missed or delayed diagnosis
The distinction between a missed infection or delayed diagnosis and an acute infection can be challenging to make. In the circumstance where it is obvious a deep infection has been ongoing for more than several days untreated, a more aggressive surgical approach is required. In this unfortunate circumstance, urgent surgical debridement including early graft and hardware removal likely gives the best chance at eradicating the established infective process. Particular attention should be made to the tunnels ensuring an adequate debridement in order to avoid the risk of ongoing osteomyelitis. The threshold for employing accessory posterior medial and/or posterior lateral portals to facilitate a complete synovectomy under these circumstances is low. The additional use of a formal arthrotomy should be considered if it increases the adequacy of the debridement. All patients should undergo an additional irrigation and debridement at approximately 48 h for delayed cases and sequential debridements may well be necessary to eradicate the infection.
Recalcitrant infections
Despite the best efforts to quickly diagnose and treat postoperative septic arthritis, the risk of continued infection remains real. For this reason, repeat irrigation and debridement is likely of significant benefit in most cases. Even though an expedient repeat surgical intervention may occur, clinical signs suggestive of ongoing infection can persist. In the case of ongoing infectious symptoms despite two consecutive irrigation and debridements, the most prudent intervention is graft and hardware removal and an aggressive complete synovectomy. The concern being that the graft, hardware, or synovium remain an untreated nidus of infection. Graft tunnels should be thoroughly debrided, removing all residual graft and debris—reamers may be particularly helpful in this regard. In one study, where removed grafts were sent to pathology, inflammatory infiltrates were found within the substance of the graft the majority of the time—creating concern it may serve to harbour infection and provide a culture media of sorts [15]. The primary goal is eradication of the infection and protection of the articular cartilage. This philosophy has led some authors to suggest graft removal during the initial intervention. This is likely overly aggressive as a majority of investigations have shown successful elimination of infection with graft preservation. However, if infection persists after two consecutive irrigation and debridements, sacrificing the knee stability in order to successfully eradicate the infection is prudent.
In the resistant infection, consideration must be made for the possibility of less common pathogens or polymicrobial infections. In these situations incorrect or insufficient antibiotics may be being administered. Zalavras’ investigation of recalcitrant cases demonstrated 3/5 (60 %) of cases were polymicrobial [45]. They advocated aggressive arthrotomy, synovectomy, and graft removal in these cases. Additionally, repeat aspirations and broader spectrum antibiotics may play a more significant role in these settings.
In the rare but unfortunate situation, where despite repeated washouts and graft/hardware removal infection persists, ruling out osteomyelitis with bone abscess as the cause is important. In these rare situations, MRI scan can be valuable. If osteomyelitis (involucrum or sequestrum) is diagnosed, an urgent and aggressive debridement of the bone is recommended. Severe osteomyelitis requiring additional surgery and bone grafting has been reported very infrequently [2].
Revision ACL reconstruction
If the graft is incompetent and removed during the first surgical intervention, or removed during a subsequent debridement, revision reconstruction should be approached judiciously. This unfortunate circumstance mandates a lengthy discussion with the patient regarding the possibility of repeat infection (and potential sepsis) as well as the pros and cons of a significant revision surgical intervention with its own inherent risks. In the case where revision surgery is desired to address ongoing symptomatic knee instability, a minimum of 6 weeks off of antibiotics is recommended. Inflammatory markers including ESR and CRP must be normalized, and at least two serial knee aspirates must be negative. In most instances, this likely means a minimum of 3–6 months after the initial surgical intervention for septic arthritis. The traumatic experience to the patient having to deal with multiple surgeries should not be understated. For this reason, further surgical interventions should be personalized to accommodate the best interest of the individual. In one series where seven grafts were removed for infection on the initial surgical intervention, 3/7 patients decided against subsequent ACL reconstruction [3]. Additionally, the value of ACL reconstruction in a post-septic arthritic knee may be of less value and depending on the symptomatology of the individual. That is, if a patient’s symptoms and decreased quality of life are focused more on post-arthritic pain and not instability, treatment should be focused on the arthritis and not revision ACL reconstruction.
Intraoperative contamination
Intraoperative contamination of the graft, poses a relatively unique challenge. In the unfortunate event that the graft comes into contact with unsterile conditions (e.g. the dropped graft) a predetermined plan of action should be in place. The dilemma of washing the graft, harvesting an alternative autograft, or using an allograft is troubling, each with its own inherent risks and benefits. Our practice is to have a backup allograft available for these situations. In the event that an allograft back up is not available, determined to be unsuitable, or not anticipated (e.g. preoperative consent not obtained), several regimens for decontamination have been suggested. From what little research on this topic exists, evidence for washing the graft and implantation exists [46, 47].
A simple and effective method of graft decontamination was described and tested by Parker et al. [48]. Their technique of “mechanical agitation and serial dilution” included ten serial washes in 100 cc of polymyxin B antibiotic solution (166 u/cc), each time agitated with 15 s of gentle shaking. This method proved superior to both antibiotic soak alone and pulsatile lavage. What solution to use to wash the graft is clearly debatable, but antibiotic impregnated or chlorohexidine gluconate-based solutions may be superior to providine-iodine solutions [49].
When allografts are used for ACL reconstruction, a sample is often sent for culture and sensitivity. Although the results of these cultures are frequently positive (5.7–13.25 %), no evidence of detrimental effects on the ACL reconstructed knee exist [26, 27, 29Related posts:
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