59 Explant/Insertion of Spacer for Infected Shoulder Arthroplasty
Abstract
The explant or insertion of an antibiotic spacer in the setting of an infected shoulder arthroplasty can be challenging and fraught with complication, but outcomes can be improved with a methodological approach. Addressing a periprosthetic shoulder infection starts with a thorough workup and identification of the offending organism. Initial debridement and removal of components is of paramount importance for infection eradication. Antibiotic cement spacers can provide local antibiotic delivery while maintaining soft-tissue tension and shoulder function until infection eradication can be achieved. There are a variety of ways to construct a cement spacer. It is to a surgeon’s benefit to have these varying techniques in their repertoire. No matter which type is employed, it is imperative to have a primary plan for implantation and removal, followed by sequential backup options should the primary plan not work.
59.1 Goals of Procedure
59.1.1 Eradication of Infection
The primary goal of management of an infected shoulder arthroplasty is eradication of the infection. Most bacteria have the ability to create a polysaccharide biofilm and adhere to foreign material and devitalized tissue, rendering them impervious to antibiotic therapy alone. Clearance of a chronic periprosthetic joint infection can only be successful with removal of all implants and debridement of devitalized tissue. An antibiotic spacer is then inserted and used for local delivery of antibiotics in conjunction with systemic intravenous antibiotics.
59.1.2 Improvement in Pain
One of the most consistent findings in any periprosthetic joint infection is the subjective symptom of pain. The range of severity can vary from minor to debilitating. Control of the infection is the only means by which to improve a patient’s pain. Removal of the compromised prosthesis without placement of another implant or spacer compromises joint function and can lead to persistent pain.
59.1.3 Maintenance of Function
In addition to local delivery of antibiotics, a spacer can provide a means of articulation, thus providing glenohumeral mobility and extremity function. It also functions to preserve the soft-tissue envelope and prevent significant contractures, thereby maintaining tissue planes and improving the feasibility of a second-stage reimplantation.
59.2 Advantages
59.2.1 Local Antibiotic Delivery
Following a thorough debridement, insertion of an antibiotic spacer provides local delivery of antibiotics and time for infection clearance. Certain antibiotics, such as gentamicin, have a better bony penetrance via dissolution from a spacer than they do systemically. The delivery of high doses of antibiotics from a spacer directly to the site of infection can achieve concentrations higher than those reached with systemic antibiotics alone, while at the same time avoiding the potential systemic toxicity that can arise from high-dose intravenous use.
59.2.2 Pathogen Identification
The reported sensitivity of joint aspiration in diagnosing a prosthetic joint infection ranges from 12 to 100%, with the majority of studies demonstrating a sensitivity between 45 and 75%. 1 , 2 When a pathogen cannot be identified via a preoperative aspirate, performing a two-stage procedure allows for deep tissue cultures to be obtained, and antibiotics to be tailored to sensitivities of bacterial cultures prior to reimplantation of hardware.
59.2.3 Single-versus Two-Stage Reconstruction
The current gold standard for treatment of chronic infections of the hip and knee is a two-stage revision. This has also shown favorable results in the shoulder. 3 , 4 This includes removal of the prosthesis and all hardware, a thorough debridement of all devitalized tissue, insertion of an antibiotic-impregnated cement spacer, followed by at least 6 weeks of intravenous antibiotics with assurance of infection eradication prior to second-stage revision, and reimplantation of components.
59.3 Indications
Implantation of an antibiotic cement spacer is performed in cases of documented or highly suspected chronic prosthetic joint infection. The removal of a spacer is performed when there is reason to believe the infection has been eradicated. We allow at least 6 weeks’ duration of systemic antibiotic therapy, followed by a 4- to 6-week antibiotic holiday. If subjective symptoms and serologic markers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], or interleukin-6 [IL-6]) remain normal, the patient is sent for a guided aspiration of the joint (with cultures held for 14 days) to confirm the absence of persistent infection. If this aspiration is negative, then the second-stage procedure can be undertaken.
59.4 Contraindications
Implanting or explanting an antibiotic spacer should not be undertaken if a patient is medically unfit for surgery. In the case of a periprosthetic joint infection, if the patient is relatively asymptomatic or is elderly, frail, or has an unacceptable level of medical risk to undergo another surgical procedure, chronic suppressive antibiotic therapy alone with retention of the implanted prosthesis is an option. In the setting of an acute prosthetic infection with a typical bacterial pathogen, irrigation and debridement with polyethylene exchange and retention of components is currently considered the standard of care. For patients who have already undergone stage I with implantation of an articulating spacer, retention of the spacer as definitive treatment can be an alternative to second-stage reimplantation. 4 – 8 This is typically seen in patients who are low demand, have severe medical comorbidities, or who decline a second-stage reimplantation due to satisfactory symptoms and/or function with their retained spacer.
59.5 Preoperative Preparation/Positioning
59.5.1 Infectious Workup
Wound Appearance
The surgical wound is evaluated for signs of infection including erythema, warmth, delayed closure with drainage, fistula formation, or subcutaneous fluid collection. The location of the prior incision can have ramifications with regard to surgical planning and the approach for explantation and spacer placement.
Imaging
Standard shoulder radiographs consisting of a true anteroposterior (AP; Grashey) view and axillary lateral view are obtained and evaluated for signs of humeral or glenoid component loosening. Further imaging workup in these cases often includes CT scan with or without intra-articular contrast to assess the soft-tissue envelope, glenoid and humeral bone stock, and prosthetic positioning and version, and to plan extraction of the current implant.
Labs
Blood laboratory values are obtained evaluating for leukocyte count, ESR, and CRP. If hematogenous origin is suspected, blood cultures can also be obtained.
Aspirate
We prefer to perform a radiographic-guided aspirate of the glenohumeral joint in order to reliably obtain an intra-articular fluid sample.
Related posts:
45 Posterior Glenoid Wear in Total Shoulder Replacement: Eccentric Reaming
48 Convertible Components in Shoulder Arthroplasty
53 Internal Latissimus Transfer for Reverse Shoulder Arthroplasty
43 Stemless Anatomic Shoulder Replacement
47 Bone Grafting for B2/B3 Glenoid
39 Deltopectoral Approach for Shoulder Arthroplasty
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