Drying of open animal joints in vivo subsequently causes cartilage degeneration.
OBJECTIVE
During open orthopaedic surgery, joints may be exposed to air, potentially leading to cartilage drying and chondrocyte death, however, the long-term effects of joint drying in vivo are poorly understood. We used an animal model to investigate the subsequent effects of joint drying on cartilage and chondrocytes.


METHODS
The patellar groove of anaesthetised rats was exposed (sham-operated), or exposed and then subjected to laminar airflow (0.25m/s; 60 minutes) before wounds were sutured and animals recovered. Animals were monitored for up to eight weeks and then sacrificed. Cartilage and chondrocyte properties were studied by histology and confocal microscopy, respectively.


RESULTS
Joint drying caused extensive chondrocyte death within the superficial regions of cartilage. Histology of dried cartilage demonstrated a loss of surface integrity at four weeks, fibrillations at eight weeks, and an increased modified Mankin score (p < 0.001). Cartilage thickness increased (p < 0.001), whereas chondrocyte density decreased at four weeks (p < 0.001), but then increased towards sham-operated levels (p < 0.01) at eight weeks. By week eight, chondrocyte pairing/clustering and cell volume increased (p < 0.05; p < 0.001, respectively).


CONCLUSIONS
These in vivo results demonstrated for the first time that as a result of laminar airflow, cartilage degeneration occurred which has characteristics similar to those seen in early osteoarthritis. Maintenance of adequate cartilage hydration during open orthopaedic surgery is therefore of paramount importance.Cite this article: Dr A. Hall. Drying of open animal joints in vivo subsequently causes cartilage degeneration. Bone Joint Res 2016;5:137-144. DOI: 10.1302/2046-3758.54.2000594.
Centre for Integrative Physiology, University of Edinburgh, Deanery of Biomedical Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK.
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Paterson
Centre for Integrative Physiology, University of Edinburgh, Deanery of Biomedical Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK.
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Eltawil
Department of Orthopaedics, Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 4SA, UK.
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Simpson
Department of Orthopaedic and Trauma Surgery, University of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK.
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Amin
Centre for Integrative Physiology, University of Edinburgh, Deanery of Biomedical Sciences, Hugh Robson Building, George Square, Edinburgh EH8 9XD, UK a.hall@ed.ac.uk.
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Hall
cartilage; chondrocyte; drying; orthopaedic surgery; osteoarthritis