Regional perfusion of carpal tissues by forced intramedullary administration of fluids was evaluated in 10 horses. Results of subtraction radiography after perfusion with a contrast medium demonstrated that perfusate was delivered to the carpal tissues by the venous system. Perfused India ink was distributed uniformly in the antebrachiocarpal and middle carpal synovial membranes. Histologically, the ink was within the venules of the synovial villi. Immediately after perfusion with gentamicin sulfate (1 g), the gentamicin concentrations in the synovial fluid and synovial membrane of the antebrachiocarpal joint were 349 +/- 240 micrograms/mL and 358 +/- 264 micrograms/g, respectively. When gentamicin concentrations in the synovial fluid of the antebrachiocarpal joint and serum were measured 0, 0.5, 1, 4, 8, 12, and 24 hours after carpal perfusion, the mean peak gentamicin concentration in the synovial fluid was 589 +/- 429 micrograms/mL. At hour 24, the mean gentamicin concentration in the synovial fluid was 4.8 +/- 2.0 micrograms/mL. The resulting peak gentamicin concentration in the serum was 23.7 +/- 14.5 micrograms/mL immediately after the perfusion; it decreased below the desired trough level of 1 micrograms/mL between hours 4 and 8.

Septic arthritis was induced in one antebrachiocarpal joint of seven horses by the intra-articular injection of 1 mL Staphylococcus aureus suspension containing a mean of 10(5) colony-forming units. Twenty-four hours after inoculation, four horses were treated by regional perfusion with 1 g of gentamicin sulfate, and three horses received 2.2 mg/kg gentamicin sulfate intravenously (IV) every 6 hours. Synovial fluid was collected for culture and cytology at regular intervals, and the synovial membranes were collected for culture and histologic examination at euthanasia 24 hours after the first treatment. Gentamicin concentration in the septic synovial fluid after three successful perfusions was 221.2 +/- 71.4 (SD) micrograms/mL; after gentamicin IV, it was 7.6 +/- 1.6 (SD) micrograms/mL. The mean leukocyte count in the inoculated joints decreased significantly by hour 24 in the successfully perfused joints. Terminal bacterial cultures of synovial fluid and synovial membranes were negative in two horses with successfully perfused joints. S. aureus was isolated from the infected joints in all three horses treated with gentamicin IV.

An autograft of periosteal tissue containing cambium cells has potential to become chondrogenic or osteogenic depending on the regeneration repair strategies. The potential number of harvestable cambium cells diminishes with age. Other factors may be associated with a reduction in the number or variable yields of cambium cells including harvest technique, harvest site location, and the time interval from harvest to implantation. Attempts to increase the number of cambium cells have included improvements in harvesting and handling technique, and expansion of the cells in tissue culture. An "in situ" stimulation and proliferation technique would offer the potential for increasing the number of cambium cells in a cost-effective manner for transplantation without the need for expansion in tissue culture.The hypothesis tested was that surgical release of the periosteum and its deep inner underlying cambium layer by sharply incising through the superficial periosteal fibrous layer down to and scoring the cortical bone surface would increase the number of cambium cells that could be harvested at a later time period. Two techniques for periosteal release were used to stimulate a proliferation of the underlying cambium layer and increase the cambium cells for harvest in skeletally mature goats: ( I ) sharply scoring all four-sides of the tissue test site perimeter, and (2) sharply scoring only two sides of the tissue test site.The two-sided and four-sided release scoring of the periosteum induced stimulatory responses in the number of cambium cells. In addition, a marked increase in mRNA expression for BMP-2 (p < 0.001) was observed within 24 h and remained elevated over baseline values for up to 96 h after this stimulation to the cambium layer.

The proximal humeral chondroepiphysis of newborn pups was shown to be well-vascularized by a series of segmentally distributed cartilage canals which varied from short unbranched channels to channels which coursed half-way across the epiphysis. Cartilage canals were observed to contain a muscular arteriole, venule, loose connective tissue and perivascular capillaries. The muscular arterioles originated from the dense perichondrial vascular network at regular intervals, coursed in the central portion of the cartilage canal, and terminated by dividing into a capillary glomerulus in the cartilaginous matrix.These glomeruli were observed to assume a wide variety of sizes and shapes reflecting the metabolic needs of the areas they served. The capillaries of the glomerulus recombined into a single venule which rejoined the perichondrium via the same channel as the parent arteriole. The loose connective tissue surrounding these vessels was rich in fibroblasts and macrophages and was continuous with that of the perichondrium.From the structural relationship of the cartilage canals and the articular surface, it was concluded that at birth the synovial fluid had little nutritional significance for the epiphysis, but with age the nutritional contribution from the synovial fluid became more important.The particular arrangement of the venule and the perivascular capillaries allowed for metabolic exchange the entire length of the canal. Structures which appeared to be unmyelinated nerves and structures which contained a flocculent material and resembled lymphatics were seen in the connective tissue of the cartilage canals.

Thin images of living articular cartilage using NLOM may be obtained with (sub-)cellular resolution at varying depths without fixing, sectioning or staining. Extracellular matrical collagen and chondron may be imaged separately in native tissue using spectrally distinct, endogenous, nonlinear optical signals. NLOM was sensitive to macromolecular composition and pathologic changes in articular cartilage matrix. Advances in instrumentation may lead to the application of NLOM to study articular cartilage in vivo.