Joint pressure influences synovial tissue blood flow as determined by colored microspheres

Comparison of Arthroscopic Lavage and Needle Lavage Techniques, and Lavage Volume on the Recovery of Colored Microspheres From the Tarsocrural Joints of Cadaver Horses

OBJECTIVE

To quantify recovery of colored microspheres from normal cadaver tarsocrural joints using arthroscopic or needle lavage with 1-5 L of fluid.

STUDY DESIGN

Ex vivo experimental study.

ANIMALS

Adult Quarter Horse cadavers (n = 8).

METHODS

After euthanasia, 1.5 × 10(6)  colored microspheres were injected into each tarsocrural joint. Each joint was randomly assigned to receive lavage (5 L 0.9% NaCl) with an arthroscope (dorsomedial arthroscope and dorsolateral egress cannula) or three 14 g needles (dorsomedial ingress, dorsolateral, and plantarolateral egress). Egress fluid from each liter was collected separately over time and the number of microspheres present in each recovered liter determined by spectrophotometry.

RESULTS

A significant interaction was present between treatment group and liter of fluid (P < .01). The number of microspheres recovered in the first liter of lavage fluid was significantly higher in the needle lavage group than in the arthroscopic lavage group (P < .01). For both groups, the number of microspheres recovered in the first liter of lavage fluid represented a majority of the total microspheres collected and was significantly different from each subsequent liter collected (P < .01). The number of microspheres recovered did not differ between liters 2, 3, 4, and 5 within or between treatment groups.

CONCLUSION

In this model, tarsocrural lavage with three 14 g needles was more effective at removing colored microspheres from the joint than arthroscopic lavage, suggesting that the number or placement of portals present may be more important than portal size and flow rate. No difference in microsphere recovery was seen with lavage volumes >1 L.

Diagnosis and Treatment of Septic Arthritis

Septic arthritis (SA) is a common orthopedic condition encountered in horses that are presented to equine veterinarians. Successful out-come is dependent on prompt and thorough evaluation and treatment. This article briefly reviews the pathophysiology, outlines diagnostics, describes treatment options and prognostics, and discusses current research in diagnosis and treatment of SA.

Effect of foot balance on the intra-articular pressure in the distal interphalangeal joint in vitro

REASONS FOR PERFORMING STUDY

Increased joint pressure has been implicated in the progression of osteoarthritis.

HYPOTHESIS

That intra-articular pressure in the distal interphalangeal joint (DIP) is significantly higher in legs loaded with heel up (HU), low heel (TU), lateral side up (LU) and medial side up (MU) imbalance compared to the balanced position.

METHODS

Twelve elbow down limbs were compressed in a hydraulic loading jig and DIP pressure measured.

RESULTS

Elevating the heels by 5 degrees significantly increased DIP pressure. After 5 ml of contrast was injected into the joint, heel elevation caused a greater increase in DIP pressure and heel lowering decreased DIP pressure. Silicone rubber castings were taken of 20 DIP whilst under load. The articular contact area was localised on the dorsal aspect in the HU position, palmar aspect in the TU position and towards the elevated side with lateromedial imbalance.

CONCLUSIONS

Altered foot orientation, which could result from trimming and shoeing, therefore influences intra-articular pressure in the DIP and the articular contact area.

POTENTIAL CLINICAL RELEVANCE

The results support the view that a balanced foot is the ideal and that the elevated heels may be detrimental to long term viability of the DIP joint.

Effect of intraluminal distention on microvascular perfusion in the equine small colon

OBJECTIVE

To determine the effect of experimental intraluminal distention on microvascular perfusion of the small colon in horses.

ANIMALS

6 mixed-breed healthy horses (mean age [+/- SDI, 9.1 +/- 2 years).

PROCEDURE

Under general anesthesia, the small colon was exposed by celiotomy and 3 segments were demarcated. In 1 of these segments, intraluminal obstruction was created by placement of a latex balloon inflated to a pressure of 40 mm Hg (obstructed segment). The other segments were the sham-operated segment and the control segment. Microvascular perfusion was evaluated in the mucosal, submucosal, muscular, and serosal layers by injection of 15 microm-diameter colored microspheres into branches of the caudal mesenteric artery. Recovery of microspheres was performed by tissue digestion, washing, and centrifugation. Distribution of microspheres in the intestinal layers was evaluated by direct observation of stained frozen sections by light microscopy.

RESULTS

A significant reduction was observed in total microvascular perfusion of obstructed segments, which was 26.4% of that of control segments. This reduction was not evident in the mucosal layer.

CONCLUSIONS AND CLINICAL RELEVANCE

Intraluminal distention of the equine small colon wall can promote ischemia by a reduction in microvascular perfusion in the intestinal wall. Intestinal layers do not seem to be affected to the same extent, because the absolute value for mucosal perfusion did not decrease in the obstructed segment.

Intra-articular pressure, elastance and range of motion in healthy and injured racehorse metacarpophalangeal joints

The objective of this study was to determine if intraarticular pressure, elastance of the soft tissue forming the dorsal pouch, and range of motion in flexion measurements are significantly different in Thoroughbred metacarpophalangeal joints with clinical evidence of idiopathic synovitis, primary synovitis, synovitis/capsulitis, or osteoarthritis relative to clinically normal joints. Forty-two metacarpophalangeal joints, in 25 active or retired Thoroughbred racehorses, were categorised by palpation and visual inspection of the palmar pouch into one of 4 increasing grades of distention. Intra-articular pressures were then measured using 2 pressure transducers attached to 22-gauge needles from both the dorsal and palmar pouches simultaneously while the horses stood squarely under mild sedation. After obtaining baseline pressure measurements, a third needle was inserted into the dorsal pouch, and 0.5 ml increments of saline solution were added every 10 s to perform a pressure/volume (elastance) study of the dorsal pouch. The elastance study for each joint ended when leakage into the palmar pouch was detected by the pressure transducer placed in that region. A lateral radiographic view was taken of each metacarpophalangeal joint in maximal flexion. The maximum angle of flexion was measured from the radiograph, and this angle was subtracted from 180 degrees to acquire the range of motion in flexion. In this study, all Thoroughbreds with clinical evidence of lameness and/or sensitivity to flexion, referable to the metacarpophalangeal joint region, had fluid distention of the palmar pouch (grade 2 or 3 distention). The 16 metacarpophalangeal joints with no clinical abnormalities had a mean palmar pouch pressure of -1.25 mmHg. Joints afflicted with synovitis/capsulitis had the highest intraarticular pressures (mean +51.00 mmHg); however, joints with idiopathic synovitis (mean +15.71 mmHg), primary synovitis (mean +28.33 mmHg) and osteoarthritis (mean +26.20 mmHg) also had significantly elevated intraarticular pressures relative to the clinically normal group. Thoroughbred metacarpophalangeal joints diagnosed with synovitis/capsulitis, or osteoarthritis, had significantly increased elastance (stiffness) of the soft tissue forming the dorsal pouch relative to the normal group and, probably, as a result significantly decreased range of motion in flexion. The presence of primary synovitis alone did not have a significant immediate effect on elastance of the dorsal pouch and range of motion in flexion. The 16 Thoroughbred metacarpophalangeal joints assessed as having no clinical abnormalities had a mean range of motion in flexion of 60.81 degrees. The mean range of motion in flexion of Thoroughbred metacarpophalangeal joints with a clinical diagnosis of primary synovitis was 53.67 degrees; idiopathic synovitis 52.14 degrees; synovitis/capsulitis 44.20 degrees; and those with radiographic evidence of moderate to marked osteoarthritis 30.80 degrees. This study demonstrated that, as the severity of the clinical evidence of metacarpophalangeal joint injury/disease increased, the range of motion in flexion decreased.