Management of failed metal-backed glenoid component in patients with bilateral total shoulder arthroplasty
A 75-year-old male presented to the clinic with a history hemochromatosis and bilateral glenohumeral arthritis status post-bilateral total shoulder replacements (left shoulder in 1999 and right shoulder in 2002). Both shoulders were also replaced with the Kirschner modular II-C components (Kirschner Medical Corp., Fair Lawn, New Jersey, USA).\nIn terms of the left shoulder, patient reported several years of good pain relief and functional improvements after the shoulder replacement. However, he started to have intermittent left shoulder pain about 8 years after surgery that progressed to constant pain and significant limitation in terms of his range of motion and also functional activities. On physical examination, his FF was 0-80, ER of 0-45 and internal rotation to L3. He also had significant pain with any range of motion on examination and strength testing demonstrated 4+/5 in supraspinatus and 4–/5 in ER. Anteroposterior radiograph of the left shoulder showed catastrophic failure of the metal-backed glenoid component with breakage of both screws []. Given the pain and functional impairment, the patient underwent revision arthroplasty with removal of the metal-backed glenoid and humeral components. Intraoperatively, significant metallosis was encountered. In addition, there was a concern for infection. Intraoperative frozen section indicated acute inflammatory reaction with a high WBC seen on the high-powered field. Based on the high probability of a coexistent infection, a decision was made to place prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) antibiotic humeral component and bone graft the glenoid cavitary defect with iliac crest autograft bone graft. Subsequently, intraoperative cultures grew both Methicillin-resistant Staphylococcus aureus (MRSA) and Propionibacterium acnes. Patient was treated with 8 weeks of intravenous antibiotics and Peripherally Inserted Central Catheter (PICC) line. Arthroscopic biopsy was then performed and demonstrated no evidence of persistent infection. Patient underwent revision arthroplasty to a custom reverse prosthesis component (Biomet comprehensive custom reverse prosthesis, Warsaw, IN) in 2008. Patient tolerated the procedure well with no intraoperative or post-operative complications. On the most recent follow-up (2012), patient had no pain on the left shoulder. His range of motion measurements were: FF = 0-170, abduction = 0-95, ER = 0-30 []. Radiographs revealed the custom reverse prosthesis was stable without evidence of loosening or failure []. His SST and ASES measured 83 and 78 respectively.\nOn the right shoulder, patient also reported progressive intermittent pain that started about 6 years after the initial procedure. This progressed to constant pain and significant limitations on the overall range of motion. On physical exam, patient's range of motion was: FF = 0-60 passive, ER = 0-20 and IR to the side only. He also had significant weakness with supraspinatus and ER testing. Radiographs revealed lucency behind the metal-backed glenoid without failure of the two screws as well as marked decrease in the space between the humeral head and metal-backed glenoid indicating wear []. Patient underwent revision arthroplasty with removal of the glenoid component and humeral modular head. An intraoperative biopsy was also obtained, which was positive for P. Acnes and subsequent placement of a PROSTALAC spacer was performed. Furthermore, he had a prolonged course of IV penicillin via PICC line. In 2010, patient underwent a revision arthroplasty with reverse shoulder prosthesis (Tornier Aequalis Reverse system. Bloomington, MN) and iliac crest bone graft of the glenoid. Harvesting of the iliac crest was performed with an oscillating saw and a 3 cm × 3 cm tri-cortical crest was obtained. The iliac crest was shaped to fit the glenoid defect and the metaglene was fixed onto the crest and native glenoid with a central plug and two compression screws. Patient tolerated the procedure well with no intraoperative or post-operative complications. On the most recent follow-up (2 years post-op), range of motion: FF = 0-120, abduction = 0-80, ER 0-75 and IR to back pocket []. He reports minimal pain on the right and no limitations to his activities of daily living. Radiographs demonstrate the reverse prosthesis in a good position without evidence of loosening or failure []. His SST and ASES scores measured 100 and 88 points respectively.