From the Guidelines
For a workup on reverse shoulder hardware loosening, I recommend a comprehensive evaluation including plain radiographs (AP, axillary, and scapular Y views), CT scan with metal artifact reduction protocol, and laboratory tests including complete blood count, erythrocyte sedimentation rate, and C-reactive protein to rule out infection. The patient should be assessed for pain patterns, particularly with activity or at rest, decreased range of motion, and any audible or palpable crepitus. If infection is suspected, joint aspiration with fluid analysis and culture should be performed 1. Treatment depends on the cause of loosening, which may include aseptic loosening due to mechanical factors, infection, or trauma. Revision surgery is often necessary for symptomatic hardware loosening, though conservative management with activity modification and physical therapy may be appropriate for patients with minimal symptoms or those who are poor surgical candidates.
Key Considerations
- Hardware loosening typically occurs due to inadequate initial fixation, bone resorption around components, or mechanical stresses exceeding the strength of the bone-implant interface 1.
- Early diagnosis is crucial as continued loosening can lead to bone loss, making revision surgery more complex.
- The presence of scapular notching on postoperative radiographs of reverse total shoulder prostheses has been associated with poor clinical outcomes 1.
- A 3-phase bone scan with SPECT or SPECT/CT can be useful in detecting acute osteomyelitis, but its specificity is low due to overlap with other abnormalities such as mechanical loosening with osteolysis and periprosthetic fracture 1.
Diagnostic Approach
- Plain radiographs (AP, axillary, and scapular Y views) should be obtained to assess the hardware components, alignment, and surrounding osseous and soft-tissue structures.
- CT scan with metal artifact reduction protocol can provide more detailed information about the bone-implant interface and surrounding structures.
- Laboratory tests, including complete blood count, erythrocyte sedimentation rate, and C-reactive protein, should be performed to rule out infection.
- Joint aspiration with fluid analysis and culture should be performed if infection is suspected.
From the Research
Reverse Shoulder Hardware Loosening
- Reverse shoulder arthroplasty (RSA) is a surgical procedure used to treat various shoulder conditions, including rotator cuff arthropathy and proximal humerus fractures 2, 3.
- Glenoid component loosening is a common cause of failure in anatomical total shoulder arthroplasty (TSA) and can be associated with glenoid bone loss 2.
- Revision RSA for the treatment of loosening of an anatomical polyethylene component has been shown to result in significant improvements in terms of pain and motion, but it is not universally successful and has a 17% glenoid mechanical failure rate 2.
Glenoid Loosening
- Glenoid loosening is a primary cause of failure in TSA and can be associated with glenoid bone loss 2, 3.
- Revision with a RSA is a reliable therapeutic option for treating glenoid loosening, providing the double benefit of glenoid bone stock reconstruction and solving the problem of soft tissue insufficiency and prosthetic instability 3.
- However, the rate of postoperative complications and subsequent reoperations is high, and the surgical technique is demanding 3.
Humeral Loosening
- Humeral loosening is a rare complication in RSA, representing approximately 1% of total complications 4.
- The incidence of radiographic aseptic loosening of the humeral component in RSA is low, with a reported rate of 0.74% 5.
- Press-fit fixation may provide a lower risk of stem loosening compared to cemented fixation 5.
Treatment Options
- Conservative treatment, glenoid revision, and conversion to hemiarthroplasty are treatment options for glenoid loosening following RSA 6.
- Conservative treatment and glenoid revision have been shown to significantly improve active anterior elevation, total Constant score, and pain, while hemiarthroplasty does not improve range of movement or clinical scores 6.
- Multivariable analysis has confirmed that conservative treatment and glenoid revision achieve similar improvements in pain, but outcomes are significantly worse following hemiarthroplasty 6.