Intra-articular fluid pressure and pain in osteoarthritis of the hip.

We investigated the relationship between the pain experienced by 50 patients with osteoarthritis of the hip and the resting intra-articular pressure of the synovial fluid. We found a significant linear correlation between these factors, greater pain being experienced by patients with higher pressures. In 20 cases we showed that the pressure rises in extension and medial rotation and is least in flexion and mid-abduction. These results help to explain the benefits of rotation osteotomy of the hip and of psoas release. They also help explain the natural resting position of the hip in patients with an acute effusion and the fixed deformities associated with late osteoarthritis of the hip.

A solid state recorder for ambulatory monitoring of pulmonary-artery pressure.

A compact, portable recording system has been developed to record pulmonary-artery pressure in ambulatory patients. A transducer mounted on the tip of a conventional cardiac catheter is inserted percutaneously and positioned in the main pulmonary artery. Analogue circuitry, including peak and trough detectors, pre-processes the pressure/voltage waveform to yield sampled values for the systolic and diastolic pressures. Systolic and diastolic values sampled every 30 s are digitized and stored in CMOS semiconductor memory. Data acquired over a prolonged period is transferred to a microcomputer for permanent storage and subsequent analysis. Five patients were each successfully monitored for at least 24 h. The zero-level drift was less than 1% and gain stability was also better than 1% over 48 h. This device allows practical, safe, reliable and prolonged pressure recording and has wide-ranging clinical potential.

Immunohistological analysis of Tannerella forsythia-induced lesions in a murine model.

Tannerella forsythia has been implicated as a defined periodontal pathogen. In the present study a mouse model was used to determine the phenotype of leukocytes in the lesions induced by subcutaneous injections of either live (group A) or nonviable (group B) T. forsythia. Control mice (group C) received the vehicle only. Lesions were excised at days 1, 2, 4, and 7. An avidin-biotin immunoperoxidase method was used to stain infiltrating CD4+ and CD8+ T cells, CD14+ macrophages, CD19+ B cells, and neutrophils. Hematoxylin and eosin sections demonstrated lesions with central necrotic cores surrounded by neutrophils, macrophages and lymphocytes in both group A and group B mice. Lesions from control mice exhibited no or only occasional solitary leukocytes. In both groups A and B, neutrophils were the dominant leukocyte in the lesion 1 day after injection, the numbers decreasing over the 7-day experimental period. There was a relatively low mean percent of CD4+ and CD8+ T cells in the lesions and, whereas the percent of CD8+ T cells remained constant, there was a significant increase in the percent of CD4+ T cells at day 7. This increase was more evident in group A mice. The mean percent of CD14+ macrophages and CD19+ B cells remained low over the experimental period, although there was a significantly higher mean percent of CD19+ B cells at day 1. In conclusion, the results showed that immunization of mice with live T. forsythia induced a stronger immune response than nonviable organisms. The inflammatory response presented as a nonspecific immune response with evidence of an adaptive (T-cell) response by day 7. Unlike Porphyromonas gingivalis, there was no inhibition of neutrophil migration.

Bladder instability. Is the primary defect in the urethra?

The urethral response to bladder filling has been studied by synchronous measurement of four points in the proximal urethra and bladder using microtip transducers. Twelve male patients with urodynamically proven bladder instability had falls in urethral closure pressure of 30 cm of water 3 s before the unstable detrusor contraction. There was a lack of awareness of the urethral relaxation, the sensation of urgency occurring only when the detrusor contracted. The suggestion is made that the sequence of events occurring in these patients with bladder instability is fundamentally no different from a normal voiding sequence and that it may be more appropriate to re-educate the muscles of the proximal urethra than to treat the detrusor instability.

Long-term monitoring of renal pelvic pressures in man.

In spite of improvements in the techniques of radiological, urodynamic and radionuclide investigations there are patients in whom it remains very difficult to determine whether upper urinary tract dilatation is associated with obstruction. We describe a technique for the long-term monitoring of renal pelvic pressures and compare the results of this investigation with other methods. We believe that this technique is more useful than standard urodynamic tests and is of particular value in patients with equivocal pelviureteric junction obstruction and in those who have undergone previous surgery.

The effects of double J stenting on unobstructed ureters. An experimental and clinical study.

Upper tract pressure flow studies in four clinically unobstructed ureters with double J stents in situ indicated that urinary flow occurred mainly around the stent and that there was significant vesicorenal pressure transmission. This study examined the dynamics of ureteric urinary flow and morphological effects consequent upon stenting a ureter in vivo. In a porcine model, ureteric intubation caused a rise in intrapelvic pressures, hydroureter, vesicorenal reflux and generalised thickening of the ureteric wall with characteristic histological changes in the urothelium. These findings suggest that double J stents may compromise urinary drainage when ureteric obstruction is not present, urging caution in their use in the damaged, unobstructed upper urinary tract.

A comparison of bipolar and monopolar diathermy probes in experimental animals.

The effects of monopolar and bipolar diathermy were studied in laboratory animals. The power required to coagulate transected vessels in air was established and the effect of immersion in saline and water during electrocoagulation was investigated. Tissue heat conduction from each type of probe was measured and compared. Tissue damage was assessed by light microscopy of histochemically stained sections. The bipolar system operated at a lower power output (13 W) with less heat conduction, and was unaffected by the surrounding medium.