Psoriatic Arthritis Does Not Directly Attack Implanted Hardware
Psoriatic arthritis (PsA) is an inflammatory disease that attacks native joints, entheses, and bone—not the implanted hardware itself. The concern with PsA patients and implanted hardware relates to increased risk of post-operative infection around the implant, not direct inflammatory attack on the metal or prosthetic material 1.
Understanding the Disease Mechanism
PsA is characterized by:
- Inflammatory arthritis of peripheral joints with synovial inflammation, increased vascularity, and T-cell infiltration 1
- Osteoclast activation leading to bone erosion and severe osteolysis in untreated disease 1
- Enthesitis (inflammation at tendon/ligament insertion sites) and dactylitis 1, 2
The pathophysiology involves elevated TNF-α, IL-1, and matrix metalloproteinases that drive cartilage collagen breakdown and bone destruction through osteoclast precursor cell activation 1. However, this inflammatory process targets biological tissues—not inert prosthetic materials like metal or plastic implants 1.
The Real Clinical Concern: Post-Operative Infection Risk
The actual risk with PsA patients and implanted hardware is infectious complications, not inflammatory attack 1:
- Evidence is conflicting but the preponderance of data suggests psoriasis may be a risk factor for post-operative infection in orthopedic surgery, particularly hip replacement 1
- One study of 55 arthroplasties found psoriasis patients had significantly increased risk for post-operative infection versus patients with rheumatoid or osteoarthritis 1
- The largest case-control study found psoriasis was a risk factor for post-operative infection in hip replacement but not knee replacement 1
Important Caveats About Infection Risk
The National Psoriasis Foundation consensus states there is no substantial evidence that additional precautions need to be taken for plaque psoriasis patients regarding infectious risk 1. The condition does not preclude necessary procedures 1.
Clinical Implications for Patients with Existing Hardware
For patients with PsA who already have implanted hardware:
- Monitor for signs of device-related infection (fever, wound dehiscence, loosening of implant, local warmth/erythema)—not inflammatory arthritis symptoms 3
- PsA can cause progressive joint damage in adjacent native joints, with radiologic damage occurring in over 50% of patients at 10 years 4, 5
- Uncontrolled PsA causes joint destruction through osteolysis and erosion of native bone, which could theoretically affect bone-implant interfaces 1, 4
Key Distinction
The hardware itself is not a target of autoimmune inflammation. However, poorly controlled PsA can cause bone erosion around the implant site, potentially leading to mechanical loosening 1, 6. This is fundamentally different from the inflammatory process directly attacking the prosthetic material.
Management Approach
- Aggressive treatment of PsA with biologics (TNF-α inhibitors) and disease-modifying antirheumatic drugs is essential to prevent progressive joint destruction 6, 7
- Early treatment substantially improves long-term prognosis and prevents the severe osteolysis that occurs most rapidly in early disease 4, 7
- Some surgeons prefer to clear psoriatic skin prior to surgery, though no study has proven this reduces infection risk 1
The bottom line: PsA threatens the bone and soft tissues around implants through its inflammatory and erosive processes, not the hardware itself 1, 6.