AHC Tan, AK Mitra, PCC Chang, BK Tay
Department of Orthopaedic Surgery, Singapore General Hospital, Singapore

HL Nag
Department of Orthopaedic Surgery, All India Institute of Medical Sciences, India

CS Sim
Department of Pathology, Gleneagles Hospital, Singapore

PURPOSE. To investigate the harmful effects of a single episode of intra-articular bleeding on articular cartilage of rabbit knees using scanning electron microscopy.

METHODS. Autologous blood was injected into the right knee joints of 18 New Zealand white rabbits. Surface and cellular damages were examined by the scanning electron microscope (n=9) and light microscope (n=34), respectively. The injected right knees were then compared with the corresponding control left knees at one, 3, and 6 weeks after the blood injection.

RESULTS. The articular surface of the injected knees turned uniformly rough with multiple pits after one week. Maximal changes with elevations and depressions were observed at 3 weeks. These changes reversed at 6 weeks with the irregularities smoothing out. A similar pattern of transient cartilage damage was noted histologically.

CONCLUSION. Both scanning electron microscopic and light microscopic findings suggest that a single episode of intra-articular bleeding leads to articular cartilage damage but this appears to be reversible. Our findings of transient damage to the articular cartilage suggest that there is no need for intra-articular evacuation and washout following an acute episode of haemarthrosis.