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Dense innervation in pseudocapsular tissue compared to aneural interface tissue in loose totally replaced hips
Sirkku Niissalo1, Tiang-Fang Li, Seppo Santavirta
1Department of Oral Pathology and Oral Medicine, Institute of Dentistry, University of Helsinki, Finland.
The Journal of Rheumatology
|April 13, 2002
Summary
Pain from aseptic loosening of hip replacements is not caused by nerve inflammation in the interface membrane. Instead, inflammation and tissue overgrowth may stem from foreign body reactions and impaired protein degradation.
Area of Science:
- Orthopedic research
- Neuroscience
- Biomedical engineering
Background:
- Neuronal cells regulate inflammatory cells, potentially causing neurogenic inflammation.
- Sensory nerves are involved in pain sensation.
Purpose of the Study:
- To investigate the presence and role of neural structures in the interface membrane and pseudocapsular tissue surrounding loosened total hip replacements.
- To determine the contribution of neurogenic factors to pain and inflammation in aseptic loosening.
Main Methods:
- Immunohistochemical analysis of synovial membrane-like interface and pseudocapsular tissue.
- Visualization of C-sensory and sympathetic innervation.
- Assessment of neural regeneration and expression of neural markers like PGP 9.5.
Main Results:
- The interface membrane lacked C-sensory and sympathetic innervation, with only minimal neural regeneration.
- The pseudocapsule showed dense sympathetic innervation, and osteoarthritis cases exhibited C-sensory fibers.
- Fibroblast-like cells in fibrotic areas expressed the neural marker PGP 9.5.
Conclusions:
- Pain in aseptic loosening is unlikely to originate from the aneural interface membrane.
- Inflammation appears to be driven by non-neurogenic factors, including foreign bodies and micromovement.
- Impaired ubiquitin-mediated proteolysis may contribute to connective tissue overgrowth and aseptic loosening.