Introduction. This thesis reports the incidence of diffusion of mepivacaine between the forelimb distal interphalangeal joint and navicular bursa, the intercarpal and radiocarpal joints, the tarsometatarsal, centrodistal and tarsocrural joints of the hock and the three stifle compartments in the horse. Materials and methods. The serum urea and synovial fluid urea concentrations were compared in 42 horses. Known dilutions of synovial fluid were made and the acute urea concentrations compared with the expected urea concentrations. For the diffusion studies thirty-three fresh cadavers were used. Synovial structures in the forelimb foot, carpus, hock and stifle in the left limbs and an alternate adjacent synovial structure in the right limbs were injected with mepivacaine. Results. The serum urea and synovial fluid urea concentrations in 42 horses proved to be equivalent (p<0.005). Results of dilution studies in synovial fluid indicated that changes in urea concentration accurately reflect dilution. Mepivacaine was detected in 25/25 (100%) adjacent navicular bursa, distal interphalangeal, tarsometatarsal and centrodistal joints and in 20/20 (100%) lateral femorotibial and medial femorotibial joints. Diffusion between other adjacent synovial structures were: intercarpal to radiocarpal joint 24/25 (96%), radiocarpal to intercarpal joint 21/25 (84%), centrodistal to tarsocrural joint 22/25 (88%), tarsometatarsal to tarsocrural joint 23/25 (92%), lateral femorotibial to femoropatellar joint 18/20 (90%) and medial femorotibial to femoropatellar joint 17/20 (85%). Mepivacaine was detected at concentrations >0.3 mg/l ranging from a minimum of 9/25 (36%) in the intercarpal joint from radiocarpal joint injection to a maximum of 25/25 (100%) in the navicular bursa from distal interphalangeal joint injection. At mepivacaine concentrations >100 mg/l detection ranged from 2/25 (8%) in the intercarpal joint from radiocarpal joint injection to 19/25 (76%) in the centrodistal joint from tarsometatarsal joint injection. Conclusions. The results show that serum and synovial urea concentrations are the same. The results show greater diffusion of mepivacaine between adjacent synovial structures than assumed from previous anatomical, latex injection and contrast arthrography studies. Therefore, commonly performed intra-synovial local analgesic techniques in the horse are not as specific as first thought.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:651658 |
| Date | January 2000 |
| Creators | Gough, M. R. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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