Septic failure is not a septic loosening: A case report of a failed shoulder prosthesis
A 70-year-old woman presented at our outpatient department with primary glenohumeral osteoarthritis at the right side \n[]. She had osteoarthritis in multiple joints and underwent previously a bilateral total knee replacement. General medical history revealed diverticulitis, mild chronic obstructive pulmonary disease (COPD), and atrial fibrillation. Because of her persisting pain non-responding to conservative treatment, she was scheduled for a resurfacing shoulder prosthesis on the right side. Standard antibiotic prophylaxis of three gifts of 1 g cefazoline in 24 h was used. A deltopectoral approach was used during surgery and the rotator cuff was intact. The osteophytes were removed and the 44 mm uncemented resurfacing shoulder prosthesis (DePuy; Global Cap) was placed \n[]. The glenoid was sclerotic without any bone loss and microfracturing was performed with the chondropick. No wound problems occurred and the patient was discharged 2 days after surgery. The physiotherapist accompanied a standard rehabilitation program with initial restricted passive range of motion. During the first 4 months, the patient was very satisfied with painless shoulder and full range of motion.\nSince this initial period, she suffered progressive shoulder pain. At examination, there was a painful arc and the supraspinatus resistance test was painful, but there were no clinical signs of a cuff rupture. It was thought that rotator cuff tendinitis caused this pain and an arthroscopic subacromial decompression was performed. Preoperative 1 gr of cefazoline was given. During surgery the rotator cuff was intact. At this time, an infection was not considered and therefore the glenohumoral joint was neither inspected nor aspirated. However, the subacromial decompression did not relieve the complaints and the range of motion gradually decreased. At 2 years after the arthroplasty, the patient had pain on the anterior side of the shoulder, mild rest pain, increased pain whilst lifting, and a restricted forward flexion of 90° and external rotation of 50°. No clinical infectious signs were present and the cuff seemed intact. Her erythrocyte sedimentation rate (ESR) was slightly elevated since the first operation (between 30 and 45) with a normal C-reactive protein (CRP). However, the biochemical markers are not completely reliable for an infection due to her diverticulitis. The X-rays showed a well-positioned prosthesis without signs of loosening and some progression in glenoid erosion []. To exclude an infection, a culture of intra-articular fluid (obtained by fine-needle aspiration) was done, which was negative.\nBecause of the persisting pain and signs of progressive of glenoid erosion on plain radiographs, a conversion from hemi to total shoulder prosthesis was performed []. Three times cefozline was given perioperative. Intraoperative inspection of the joint showed induration of the synovium and a sclerotic glenoid with irregular erosions. The cap was macroscopically solidly incorporated in the bone. Routine swabs and tissue samples from the bone and synovium were taken for cultures. The peri- and postoperative course was uneventful with normal wound healing. However, after 10 days, all intraoperative cultures revealed a combination of micro-organisms and antibiotic therapy was started. The Pantoea agglomerans, Staphylococcus epidermidis, and Propionium acnes were found in all four operative cultures.\nThe resected resurfacing prosthesis was sent to a specialized bone lab. It was fixated in buffered formalin at 4°C and the prosthesis was cut along the central stem. After embedding of the halves in polymethyl methacrylate (PMMA), the surfaces were polished, sputter coated with cold, and examined by scanning electron microscope (SEM). Then, surfaces were polished again, acid etched to partially remove the PMMA, and then stained with basic fuchsin and photographed. A microscopic stable prosthesis with full osseointegration was seen. The bone was intact, generally osteoporotic, and in good contact with the coating of the prosthesis. There were no signs of soft tissue interface formation due to loosening or microfractures of the bone trabeculae [Figures –].\nThese findings led to the conclusion that the resurfacing prosthesis failed due to a painful low-grade infection, without loosening of the prosthesis. According to the advice of the microbiologist, prolonged antibiotic regiment was started until the ESR and CRP normalized after 3 months. The rehabilitation period was longer than after the first operation, but uneventful and no wound problems occurred. At the last follow-up, 24 months postoperative, she was satisfied with her shoulder. She had a pain-free active forward flexion of 140°, endorotation of 70°, and exorotation of 30°. There were no clinical or biochemical signs of infection and the X-ray showed a correct position of the prosthesis with no signs of loosening [].