Infected shoulder arthroplasty calls for correct diagnosis, thorough debridement

Treatments include replacement or excision arthroplasty, shoulder joint fusion and antibiotics.

Issue: September 2009

As rare as shoulder sepsis, septic shoulder arthroplasty and infected shoulder arthroplasty can be, treating these conditions appropriately can result in pain relief and the return of good shoulder function for patients, according to an orthopedic group in Cleveland.

William H. Seitz Jr., MD, discussed his group’s results at the 2009 Current Concepts in Joint Replacement Spring Meeting and shared some approaches he has found effective for diagnosing, culturing and treating shoulder infections.

“Basically in the acute onset, if we can salvage it, we try to salvage it. If not, we go to resection and then ultimately an exchange arthroplasty. If it is chronic, longer than a month or late evolution, then we will go directly to the exchange,” he said.

Improved pain, function

Among the 18 infected shoulder arthroplasty cases Seitz and colleagues treated with debridement, antibiotic spacers and secondary reconstruction, three each were due to methicillin-resistant Staphylococcus aureus (MRSA), S. epidermis and Propionibacterium acnes. They typically performed two-staged arthroplasty using temporary methylmethacrylate spacers containing tobramycin and more recently vancomycin due to the increased MRSA infection rates.

“Results in this initial group were gratifying in terms of pain relief and improvement of their function, but they all had limits in motion and decrease in strength,” Seitz explained.

This 57-year-old woman’s swollen shoulder had erythematous and pain after two rotator cuff surgeries.

He mentioned excision arthroplasty and fusion as other possible treatments.

Tricky diagnosis

For Seitz, making the diagnosis correctly and quickly is essential.

“In other words, do not miss it,” he said, noting that accurately identifying these bugs can be challenging.

For early detection he recommends sterile aspiration, culturing in broth at least 15 days to grow most bacteria and imaging.

“You will need to use all of your faculties and have a high index of suspicion,” he said. “If infection is suspected, don’t wait for culture results, act immediately to drain and débride.”

Late infections

Identifying indolent bugs can be problematic: not all the tests are positive, and white blood cell counts may not be elevated. He said signs of slow or late onset organisms include an aching or sore shoulder, but not necessarily one that is red.

After making the diagnosis, Seitz said the key is to be aggressive in early cases that develop within 1 month after arthroplasty. He recommended salvaging them via arthroscopic synovectomy and debridement or arthrotomy with the goal of removing all nonviable tissue and treating the infection with antibiotics.

Cultures revealed methicillin-resistant Staphylococcus aureus, which was treated with intravenous vancomycin for 6 weeks. However, the patient developed more redness, swelling and inflammation 3 weeks later, which was treated with more aggressive surgical debridement and inserting a large spacer.

Once the patient’s white blood cell and C-reactive protein counts and erythrocyte sedimentation rate were within normal limits, she was revised to a reverse shoulder arthroplasty implant, fixed in the glenoid with trabecular metal and in the humerus with antibiotic-impregnated cement.

Images: Seitz WH

Late or persistent early infections require removing all implants and cement, perhaps using an antibiotic-impregnated methylmethacrylate spacer in two-stage reconstructions to maintain the joint gap before placing the new implant. Seitz said he was most surprised by the increased quality of the pseudocapsule, which allowed better enclosing the arthroplasty and afforded patients increased pain relief, but typically with decreased motion.

For more information:

William H. Seitz Jr., MD, can be reached in the Department of Orthopaedic Surgery, Cleveland Clinic Lerner College of Medicine, Cleveland Orthopaedic and Spine Hospital at Lutheran, 1730 W. 25th St., Cleveland, OH 44113; 216-363-2331; e-mail: seitzw@ccf.org. He has no direct financial interest in any products or companies mentioned in this article.

Reference:

Seitz WH. The infected arthroplasty: Bacterial badlands. #17. Presented at the 10th Annual Current Concepts in Joint Replacement Spring Meeting. May 17-20, 2009. Las Vegas.