Factors affecting intraosseous pressure measurement
- PDF / 1,172,025 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 44 Downloads / 262 Views
RESEARCH ARTICLE
Open Access
Factors affecting intraosseous pressure measurement Michael Beverly*
and David Murray
Abstract Background: Although a raised intraosseous pressure (IOP) has been found in osteoarthritis and osteonecrosis, the normal physiology of subchondral circulation is poorly understood. We developed an animal model and explored the physiology of normal subchondral perfusion and IOP. Methods: In 21 anaesthetised rabbits, 44 intraosseous needles were placed in the subchondral bone of the femoral head (n = 6), femoral condyle (n = 7) or proximal tibia (n = 31). Needles were connected to pressure transducers and a chart recorder. In 14 subjects, the proximal femoral artery and vein were clamped alternately. In five subjects, arterial pressure was measured simultaneously in the opposite femoral artery. Results: The average IOP at all 44 sites was 24.5 mmHg with variability within SD 6.8 and between subjects SD 11.5. IOP was not significantly influenced by gender, weight, site or size of a needle. Needle clearance by flushing caused a prolonged drop in IOP whereas after clearance by aspiration, recovery was rapid. IOP recordings exhibited wave patterns synchronous with the arterial pulse, with respiration and with drug circulation time. There was a correlation between IOP and blood pressure (13 sites in 5 subjects, Pearson correlation 0.829, p < 0.0005). There was a correlation between IOP and the associated pulse pressure (PP) in 44 sites among 21 subjects (Pearson correlation 0.788, p < 0.001). In 14 subjects (31 sites), arterial occlusion caused a significant reduction in IOP and loss of PP (p < 0.0001). Venous occlusion significantly raised IOP with preservation of the PP (p < 0.012). Conclusion: Our study shows that subchondral cancellous bone behaves as a perfused tissue and that IOP is mainly a reflection of arterial supply. A single measure of IOP is variable and reflects only perfusion at the needle tip rather than being a measure of venous back pressure. Alternate proximal vessel clamping offers a new means of exploring the physiology of subchondral perfusion. We describe a model that will allow further study of IOP such as during loading. Keywords: Intraosseous pressure, Physiology, Subchondral, Bone blood flow, Vascular occlusion, Osteoarthritis, Osteonecrosis
Background Intraosseous pressure (IOP) and bone blood flow have been studied by authors interested in bone circulation and physiology for more than 50 years. Varying techniques using different needles, flushing and recording methods have produced differing results, and there has been limited progress in understanding IOP physiology since Azuma reported IOP fluctuation in a rabbit model in 1964 [1–7]. Measurement of IOP in man has also proved variable [8]. IOP has generally been found to be raised in bone diseases such as osteonecrosis and after steroid use [9–13]. A raised * Correspondence: [email protected] Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology & Musculoskeletal Sciences, University
Data Loading...
