Orthopedics Today Grand Rounds

A 73-year-old man with acute atraumatic shoulder pain 2 years after reverse TSA

A 73-year-old, right-hand dominant man presented with a 4-day history of right shoulder pain. He underwent reverse total shoulder arthroplasty in that shoulder 22 months prior for cuff tear arthropathy. He was doing well clinically at his last follow-up appointment at 12 months postoperatively, with forward elevation to 120°, abduction to 90°, external rotation to 30° and internal rotation to the level of his sacrum without pain.

Four days prior to this visit, he was standing in his backyard pool when he developed sudden onset of right shoulder pain. He denied any significant trauma as he was just moving his arms through the water for forward propulsion. The pain progressively worsened to the extent that he was unable to move his shoulder at all by the evening. He denied any fevers, chills, night sweats or constitutional symptoms. He also denied recently undergoing dental work or other invasive procedures. Notably, several days prior to presentation he sustained a few mosquito bites, which he scratched, although not particularly aggressively.

The patient’s medical history is otherwise notable for chronic atrial fibrillation, for which he is anticoagulated with dabigatran (Pradaxa, Boehringer Ingelheim), gout, hypertension, hyperlipidemia and a stroke he sustained 15 years prior which resulted in mild, residual right-sided hemiparesis.

On physical exam, his vital signs were normal, and his incision was well-healed without erythema. The shoulder was moderately swollen, but not warm to touch. The patient was tender with any palpation of the shoulder. When in an upright position, he had severe pain with any active shoulder range of motion (ROM). When bending forward, the patient could perform only small pendulum motions, but even these elicited mild pain. His neurovascular exam was intact distally.

Radiographs of the right shoulder performed on the day of the clinic visit demonstrated a reverse total shoulder arthroplasty (TSA) without evidence of dislocation or loosening (Figure 1). Given the patient’s severe pain, unremarkable radiographic findings and a lack of clinical signs of infection, a mechanical cause of pain was explored further. This involved dynamic examination of the shoulder under live fluoroscopy since occult implant failure at the humeral tray-taper is a rare, but known complication of the type of modular humeral implant system implanted in this patient’s case. This revealed no signs of implant failure or humeral tray-taper dissociation (Figure 2).

Laboratory tests revealed elevated inflammatory markers with a white blood cell (WBC) count of 14.7 cells/nL (laboratory normal range < 12 cells/nL), C-reactive protein of 33.7 mg/dL (normal < 2 mg/dL) and erythrocyte sedimentation rate of 95 mm/hour (normal < 20 mm/hour).

The patient was referred for ultrasound-guided aspiration, which yielded a large amount of purulent fluid, a cell count of 57,875 WBCs per mm3 with 88% neutrophils and gram staining that demonstrated many white cells and gram-positive cocci. Preliminary culture results the next day indicated alpha-hemolytic Streptococcus species.

reverse TSA prosthesis
Figure 1. Radiographs of the patient’s right shoulder with anterior-posterior (A), axillary (B) and scapula-Y views (C) show a reverse TSA prosthesis without evidence of loosening, dislocation or hardware failure.
Figure 2. Dynamic fluoroscopic examination revealed no evidence of modular implant failure.

Source: Michael C. Fu, MD

What is your diagnosis?

See answer on next page.

Late-onset PJI of reverse TSA with alpha-hemolytic Streptococcus species

The patient was admitted to the hospital after the aspiration followed by consultations with our internal medicine and orthopedic infectious disease colleagues. His dabigatran was held. There were a number of treatment decisions to be made including surgical timing given his recent use of dabigatran, which is a direct thrombin inhibitor, and whether to use a reversal agent such as idarucizumab. In addition, consideration needed to be given to the risks and benefits of treatment with debridement, antibiotics and implant retention (DAIR) vs. complete explantation of the prosthesis and placement of an antibiotic spacer in the context of an atypical organism for shoulder periprosthetic joint infection (PJI).

With input from our multidisciplinary team, the decision was made to postpone the surgical case for 48 hours given his benign systemic clinical picture and to ensure medical optimization. He was started on empiric IV vancomycin on the day of admission and monitored for clinical deterioration. In the interim, the culture sensitivity analysis revealed the organism to be pan-sensitive, including to vancomycin. He was taken to the OR on the second day after initial presentation and the reversal agent for dabigatran, a monoclonal antibody, idarucizumab, was administered just prior to surgery. After extensive discussion with our orthopedic infectious disease team, as well as a literature review, the preoperative plan was to exchange the humeral tray, liner and glenosphere, but to retain the humeral stem and glenoid baseplate if they were found to be well-fixed.

Intraoperatively, surgical exposure was achieved through the previous deltopectoral interval. Meticulous hemostasis with electrocautery was maintained throughout the case. Upon entering the joint, a moderate amount of purulent fluid and synovitis was encountered. The humeral tray, liner and glenosphere were removed. Fluid and tissue samples were taken for culture and pathology. The joint space was copiously irrigated. The humeral stem, glenoid baseplate and baseplate screws were found to be well-fixed. Therefore, the decision was made to proceed with retaining the humeral stem and baseplate, and replacement of the humeral tray, polyethylene liner and glenosphere. Vancomycin powder (1 g) was applied in the glenohumeral space, and deep and subcutaneous drains were used. Estimated blood loss was 250 mL. Postoperative imaging revealed no evidence of fracture, dislocation or hardware abnormalities (Figure 3).

Postoperatively, the patient’s antibiotics were narrowed by our infectious disease team to IV ceftriaxone that was administered for 6 weeks through a peripherally inserted central catheter given the pan-sensitive Streptococcus species. He was started on a bridging therapeutic dose of enoxaparin postoperatively. His drain was removed on postoperative day 2 and he was restarted on dabigatran on postoperative day 4. The patient was discharged from the hospital on postoperative day 5.

postoperative radiograph
Figure 3. The immediate postoperative radiograph is shown.

With the increasing number of anatomic and reverse TSAs being performed for an expanding set of indications, the number of shoulder PJIs are expected to rise. Reported rates of PJI after TSA in the literature has ranged from less than 1% to 5%. Similar to PJI in lower extremity arthroplasty, in the shoulder it is associated with significant morbidity and the potential need for multiple operations. Depending on infection chronicity, severity, systemic involvement and the specific organism, treatment options include DAIR, one-stage exchange arthroplasty and two-stage reimplantation.

Furthermore, shoulder PJI due to Streptococcus species is rare. In a single-center series of 15 PJIs after reverse TSA during an 8-year period, Morris and colleagues had no cases of streptococcal infections. The most common organisms were Staphylococcus aureus, Propionibacterium acnes and Staphylococcus epidermidis. In a series of 32 PJIs during a 33-year period, Singh and colleagues showed Staphylococcus predominated in earlier years, but P. acnes has recently become nearly as common. They report just two cases during that time with Streptococcus species. In the lower extremity arthroplasty literature reported success rates of debridement with prosthesis retention for streptococcal PJI are 66% to 89.5%. Therefore, after discussion with the patient and our infectious disease team, we treated the infection with DAIR after it was determined the humeral stem and glenoid baseplate were well-fixed.

The source of streptococcal infection in this patient is unclear. He reported he had been scratching mosquito bites recently. Interestingly, in a retrospective series of 55 cases of streptococcal septic arthritis in native joints, Dubost and colleagues reported skin lesions were suspected to be the portal of entry for Group A and Group B Streptococcus species.

There is the possibility of humeral tray-taper failure in the initial differential diagnosis. Five such failures in modular shoulder arthroplasty humeral components were reported by McDonald and colleagues. Although the failures were mostly associated with a traumatic event, one such case occurred from just swinging a golf club. Notably, three of these cases had normal-appearing plain radiographs.

Finally, the patient’s chronic anticoagulation on dabigatran posed an additional clinical dilemma. With our multidisciplinary team, the urgency of taking the patient to surgery had to be balanced against the risks of excessive bleeding and acute reversal. Furthermore, idarucizumab used as a reversal agent for dabigatran was novel for our clinical service. The potential delay to surgery also raised the question of whether empiric antibiotics should be started preoperatively to the detriment of the value of intraoperative cultures and the contribution to fostering antibiotic resistance. These specific issues highlight the importance of close multidisciplinary collaboration with colleagues in medicine, hematology and infectious disease in complex clinical cases.

Disclosures: Warren reports he receives royalty payments from Arthrex and Zimmer Biomet, including for the implant mentioned. Fu and Ruzbarsky report no relevant financial disclosures.

A 73-year-old, right-hand dominant man presented with a 4-day history of right shoulder pain. He underwent reverse total shoulder arthroplasty in that shoulder 22 months prior for cuff tear arthropathy. He was doing well clinically at his last follow-up appointment at 12 months postoperatively, with forward elevation to 120°, abduction to 90°, external rotation to 30° and internal rotation to the level of his sacrum without pain.

Four days prior to this visit, he was standing in his backyard pool when he developed sudden onset of right shoulder pain. He denied any significant trauma as he was just moving his arms through the water for forward propulsion. The pain progressively worsened to the extent that he was unable to move his shoulder at all by the evening. He denied any fevers, chills, night sweats or constitutional symptoms. He also denied recently undergoing dental work or other invasive procedures. Notably, several days prior to presentation he sustained a few mosquito bites, which he scratched, although not particularly aggressively.

The patient’s medical history is otherwise notable for chronic atrial fibrillation, for which he is anticoagulated with dabigatran (Pradaxa, Boehringer Ingelheim), gout, hypertension, hyperlipidemia and a stroke he sustained 15 years prior which resulted in mild, residual right-sided hemiparesis.

On physical exam, his vital signs were normal, and his incision was well-healed without erythema. The shoulder was moderately swollen, but not warm to touch. The patient was tender with any palpation of the shoulder. When in an upright position, he had severe pain with any active shoulder range of motion (ROM). When bending forward, the patient could perform only small pendulum motions, but even these elicited mild pain. His neurovascular exam was intact distally.

Radiographs of the right shoulder performed on the day of the clinic visit demonstrated a reverse total shoulder arthroplasty (TSA) without evidence of dislocation or loosening (Figure 1). Given the patient’s severe pain, unremarkable radiographic findings and a lack of clinical signs of infection, a mechanical cause of pain was explored further. This involved dynamic examination of the shoulder under live fluoroscopy since occult implant failure at the humeral tray-taper is a rare, but known complication of the type of modular humeral implant system implanted in this patient’s case. This revealed no signs of implant failure or humeral tray-taper dissociation (Figure 2).

Laboratory tests revealed elevated inflammatory markers with a white blood cell (WBC) count of 14.7 cells/nL (laboratory normal range < 12 cells/nL), C-reactive protein of 33.7 mg/dL (normal < 2 mg/dL) and erythrocyte sedimentation rate of 95 mm/hour (normal < 20 mm/hour).

The patient was referred for ultrasound-guided aspiration, which yielded a large amount of purulent fluid, a cell count of 57,875 WBCs per mm3 with 88% neutrophils and gram staining that demonstrated many white cells and gram-positive cocci. Preliminary culture results the next day indicated alpha-hemolytic Streptococcus species.

reverse TSA prosthesis
Figure 1. Radiographs of the patient’s right shoulder with anterior-posterior (A), axillary (B) and scapula-Y views (C) show a reverse TSA prosthesis without evidence of loosening, dislocation or hardware failure.
Figure 2. Dynamic fluoroscopic examination revealed no evidence of modular implant failure.

Source: Michael C. Fu, MD

What is your diagnosis?

See answer on next page.

PAGE BREAK

Late-onset PJI of reverse TSA with alpha-hemolytic Streptococcus species

The patient was admitted to the hospital after the aspiration followed by consultations with our internal medicine and orthopedic infectious disease colleagues. His dabigatran was held. There were a number of treatment decisions to be made including surgical timing given his recent use of dabigatran, which is a direct thrombin inhibitor, and whether to use a reversal agent such as idarucizumab. In addition, consideration needed to be given to the risks and benefits of treatment with debridement, antibiotics and implant retention (DAIR) vs. complete explantation of the prosthesis and placement of an antibiotic spacer in the context of an atypical organism for shoulder periprosthetic joint infection (PJI).

With input from our multidisciplinary team, the decision was made to postpone the surgical case for 48 hours given his benign systemic clinical picture and to ensure medical optimization. He was started on empiric IV vancomycin on the day of admission and monitored for clinical deterioration. In the interim, the culture sensitivity analysis revealed the organism to be pan-sensitive, including to vancomycin. He was taken to the OR on the second day after initial presentation and the reversal agent for dabigatran, a monoclonal antibody, idarucizumab, was administered just prior to surgery. After extensive discussion with our orthopedic infectious disease team, as well as a literature review, the preoperative plan was to exchange the humeral tray, liner and glenosphere, but to retain the humeral stem and glenoid baseplate if they were found to be well-fixed.

Intraoperatively, surgical exposure was achieved through the previous deltopectoral interval. Meticulous hemostasis with electrocautery was maintained throughout the case. Upon entering the joint, a moderate amount of purulent fluid and synovitis was encountered. The humeral tray, liner and glenosphere were removed. Fluid and tissue samples were taken for culture and pathology. The joint space was copiously irrigated. The humeral stem, glenoid baseplate and baseplate screws were found to be well-fixed. Therefore, the decision was made to proceed with retaining the humeral stem and baseplate, and replacement of the humeral tray, polyethylene liner and glenosphere. Vancomycin powder (1 g) was applied in the glenohumeral space, and deep and subcutaneous drains were used. Estimated blood loss was 250 mL. Postoperative imaging revealed no evidence of fracture, dislocation or hardware abnormalities (Figure 3).

Postoperatively, the patient’s antibiotics were narrowed by our infectious disease team to IV ceftriaxone that was administered for 6 weeks through a peripherally inserted central catheter given the pan-sensitive Streptococcus species. He was started on a bridging therapeutic dose of enoxaparin postoperatively. His drain was removed on postoperative day 2 and he was restarted on dabigatran on postoperative day 4. The patient was discharged from the hospital on postoperative day 5.

postoperative radiograph
Figure 3. The immediate postoperative radiograph is shown.

With the increasing number of anatomic and reverse TSAs being performed for an expanding set of indications, the number of shoulder PJIs are expected to rise. Reported rates of PJI after TSA in the literature has ranged from less than 1% to 5%. Similar to PJI in lower extremity arthroplasty, in the shoulder it is associated with significant morbidity and the potential need for multiple operations. Depending on infection chronicity, severity, systemic involvement and the specific organism, treatment options include DAIR, one-stage exchange arthroplasty and two-stage reimplantation.

PAGE BREAK

Furthermore, shoulder PJI due to Streptococcus species is rare. In a single-center series of 15 PJIs after reverse TSA during an 8-year period, Morris and colleagues had no cases of streptococcal infections. The most common organisms were Staphylococcus aureus, Propionibacterium acnes and Staphylococcus epidermidis. In a series of 32 PJIs during a 33-year period, Singh and colleagues showed Staphylococcus predominated in earlier years, but P. acnes has recently become nearly as common. They report just two cases during that time with Streptococcus species. In the lower extremity arthroplasty literature reported success rates of debridement with prosthesis retention for streptococcal PJI are 66% to 89.5%. Therefore, after discussion with the patient and our infectious disease team, we treated the infection with DAIR after it was determined the humeral stem and glenoid baseplate were well-fixed.

The source of streptococcal infection in this patient is unclear. He reported he had been scratching mosquito bites recently. Interestingly, in a retrospective series of 55 cases of streptococcal septic arthritis in native joints, Dubost and colleagues reported skin lesions were suspected to be the portal of entry for Group A and Group B Streptococcus species.

There is the possibility of humeral tray-taper failure in the initial differential diagnosis. Five such failures in modular shoulder arthroplasty humeral components were reported by McDonald and colleagues. Although the failures were mostly associated with a traumatic event, one such case occurred from just swinging a golf club. Notably, three of these cases had normal-appearing plain radiographs.

Finally, the patient’s chronic anticoagulation on dabigatran posed an additional clinical dilemma. With our multidisciplinary team, the urgency of taking the patient to surgery had to be balanced against the risks of excessive bleeding and acute reversal. Furthermore, idarucizumab used as a reversal agent for dabigatran was novel for our clinical service. The potential delay to surgery also raised the question of whether empiric antibiotics should be started preoperatively to the detriment of the value of intraoperative cultures and the contribution to fostering antibiotic resistance. These specific issues highlight the importance of close multidisciplinary collaboration with colleagues in medicine, hematology and infectious disease in complex clinical cases.

Disclosures: Warren reports he receives royalty payments from Arthrex and Zimmer Biomet, including for the implant mentioned. Fu and Ruzbarsky report no relevant financial disclosures.