Shoulder and Elbow cases infected total shoulder arthroplasty

A 72-year-old, right-hand-dominant male with a history of type 2 diabetes, hypertension, and coronary artery disease presents to clinic for a second opinion regarding worsening left shoulder pain 8 months after undergoing a left total shoulder arthroplasty. He had an uncomplicated procedure and has had no major postoperative complications thus far; however, he has never been completely pain free since his procedure. He denies any recent trauma, fevers, chills, or drainage from the incision site. On examination, the incision sites are clean, dry, and intact, and he has mild tenderness to palpation diffusely over the left shoulder as well as decreased range of motion. Imaging is shown in Figure 2–55.

 

 

 

Figure 2–55

 

What is the most appropriate next step in his management?

1. Schedule the patient for soonest available irrigation and debridement of left shoulder

2. MRI with contrast to evaluate for infection

3. CT arthrogram of the left shoulder to evaluate for loosening

4. Referral to physical therapy

 

Discussion

The correct answer is (C). This patient’s story of acutely worsening pain without known trauma and with a history of orthopaedic implants is suspicious for infection. Risk factors for infection include rheumatoid arthritis, diabetes mellitus, systemic lupus erythematosus, malignancy, immunosuppression, etc. The first step in this diagnosis would be CT arthrogram of the shoulder to evaluate for loosening as sign of infection. A is incorrect as, although infection is on the differential, it has not yet definitively been diagnosed and therefore an immediate irrigation and debridement would not be indicated. MRI (Choice B) might be helpful in identifying a joint effusion or bony edema/signal intensity but would not provide as useful information as synovial fluid would at this point. Choice D is incorrect because the patient must be worked up for infection before deciding on conservative

management only. As a side note, aspiration of the glenohumeral joint would be more appropriate for cases in which bacteremic seeding of a joint is suspected.

CT arthrograms of the patient’s left shoulder are shown in Figure 2–56. CRP is <3, ESR 45. The patient continues to have pain, so you decide to perform arthroscopic biopsy to obtain tissue cultures. Frozen sections show <5 PMNs per hpf, and Gram stains are all negative.

 

 

 

Figure 2–56

 

What is the next step in management of this patient?

1. Referral to pain clinic for management of his chronic pain

2. Hold cultures for 3 weeks and await final report

3. Request tissue culture medium be changed to chocolate agar

4. Immediate conversion to open with washout of right shoulder and explanation of components

Discussion

The correct answer is (B). Figure shows contrast under the glenoid component. Given the patient’s normal inflammatory markers and frozen sections combined with continued pain and loosening on CT, infection with P. acnes (an organism that is very difficult to isolate) should be investigated by holding any cultures for at least 2 weeks to see if it will eventually grow. Chocolate agar (Choice C) is mainly used for growing species such as H. influenzae and Neisseria meningitidis not P. acnes. A is incorrect since the patient’s cell count and frozen sections are clearly abnormal, therefore referral to pain clinic would not be appropriate. However, Choice D would be too aggressive an approach given that no organisms have been isolated, frozen sections show <5 PMNs per hpf, and the patient has relatively normal inflammatory markers.

After 17 days, P. acnes is isolated from the culture medium.

 

What is the most appropriate treatment for P. acnes infection in a patient with a total shoulder arthroplasty?

1. Resection arthroplasty with implantation of antibiotic cement spacer

2. Resection arthroplasty with component exchange

3. Chronic suppression with antibiotic therapy

4. Resection arthroplasty with right shoulder arthrodesis

 

Discussion

The correct answer is (A). The patient should be treated for his infection by removing his current implants and placing an antibiotic spacer. He should also be referred to infectious diseases clinic for recommendations for antibiotic therapy. Choice B is incorrect since it would involve placement of hardware into an infected area. Choice C would be more appropriate if the patient had failed treatment with a spacer. Choice D would not be indicated at this time, and would be reserved for cases of infection that were unresponsive to long-term antibiotic treatment and caused severe pain and limited functionality in the patient.

The patient undergoes resection arthroplasty with antibiotic cement spacer and a 6-week course of IV antibiotics. He returns to clinic 4 months later with improved pain, CRP <3, however, on examination he has a positive belly press sign and increased external rotation compared with the contralateral shoulder. Imaging is shown in Figure 2–57.

 

 

 

Figure 2–57

 

What will likely be the definitive management of his infection?

1. Maintenance of antibiotic cement spacer

2. Explanation of antibiotic cement spacer with total shoulder arthroplasty

3. Additional 6 weeks of antibiotic therapy followed by rechecking CRP

4. Explanation of antibiotic cement spacer with reverse total shoulder arthroplasty

 

Discussion

The correct answer is (D). The patient has completed his course of antibiotics and his spacer and is now an appropriate candidate for explanation of the cement spacer with revision shoulder arthroplasty, therefore Choices A and C are incorrect. The patient’s clinical examination findings point to rotator cuff tear (specifically subscapularis) which has occurred in the interval between his obtaining his initial total shoulder arthroplasty and his current examination. Therefore, total shoulder arthroplasty (Choice B) is contraindicated, and the patient should have a reverse total shoulder arthroplasty.

 

Objectives: Did you learn...?

 

Recognize the clinical presentation of a patient with infection after total shoulder arthroplasty?

 

Initiate appropriate work-up of a patient with a suspected infected total shoulder arthroplasty?

 

Treat a patient with infected total shoulder arthroplasty?