Patellofemoral kinematics in mobile-bearing and fixed-bearing posterior stabilised total knee replacements: a cadaveric study.

PURPOSE: The aim was to compare the patellar kinematics in the normal knee, fixed-bearing (FB) and mobile-bearing total knee replacement (MB-TKR). The hypothesis that a mobile-bearing TKR has a more natural patellar movement was tested. METHODS: Computer navigation was used to track the patella in nine whole lower extremities in the natural knee and in the same knee with a posterior stabilised FB-TKR and a posterior stabilised MB-TKR from 0° to 90° flexion. The form and position of the trochlea in the natural knee and the patellar groove of the TKR femoral component was also analysed. RESULTS: There were no differences between the FB and MB-TKRs. But the patella in the TKRs at flexion angles of more than 50° had a more medial tilt compared to the natural knee. The patella of the natural knee tended to rotate externally with flexion, this was not seen in both TKR types. There were no significant differences in absolute mediolateral translation nor in translation relative to the patellar groove. During flexion, the patella lost contact with its groove earlier in the TKRs. The radius of the patellar groove of the femoral component was larger. The groove extended more superiorly and less far posteriorly, it was also positioned further laterally compared to the natural knee. CONCLUSIONS: There are subtle kinematic differences in patellar tracking between the natural knee and a TKR presumably due to differences in the shape and position of the patellar groove. There are no kinematic differences in patellar movement between the FB- and MB-TKR.

Hypercapnic cerebral blood flow in spontaneously hypertensive rats.

OBJECTIVE: Hypercapnic cerebral vasodilation appears to be endothelium-dependent, as it involves nitric oxide and prostaglandins. Since chronic hypertension has been associated with impaired endothelial function, we designed a study to find out whether hypercapnic cerebral blood flow and its nitric oxide- and prostaglandin-sensitive component is reduced in spontaneously hypertensive rats (SHR) compared with normotensive controls. METHODS: Cerebral blood flow was measured in enflurane-anesthetized SHR (n=53), Wistar-Kyoto (WKY, n=20) and Sprague-Dawley (n=50) rats using the hydrogen clearance method. Cerebral blood flow was measured during eucapnia and hypercapnia; it was also assessed after administering either nonisoform-selective or isoform-selective neuronal nitric oxide synthase inhibitors and during inhibition of prostaglandin production. RESULTS: Hypercapnic cerebral blood flow did not differ among the strains. Nitric oxide synthase inhibition with intracortical N(G)-monomethyl-L-arginine reduced hypercapnic cerebral blood flow in SHR by 23+/-4% and in Sprague-Dawley rats by 23+/-7% without affecting eucapnic flow. Intraperitoneal administration of the inhibitor of neuronal nitric oxide synthase, 7-nitroindazole, reduced eucapnic flow by 18+/-5% in SHR and 27+/-5% in WKY rats, and hypercapnic flow by 48+/-3 and by 51+/-6%, respectively. Indomethacin produced a similar decrease in hypercapnic flow in Sprague-Dawley rats and SHR (49+/-5 and 62+/-4%, respectively). CONCLUSION: Hypercapnic cerebral blood flow was not impaired in SHR. The contribution of nitric oxide- and prostaglandin-dependent vasodilation appeared to be intact Our results are consistent with the hypothesis that neuronal rather than endothelial production of nitric oxide may be responsible for maintaining hypercapnic cerebral vasodilation in SHR.

[Quantitative enzymatic and enzyme histochemical analysis in detecting inductive and nephrotoxic effects of various antibiotics]. / Quantitative enzymatische und enzymhistochemische Analysen zum Nachweis induktiver und nephrotoxischer Wirkungen verschiedener Antibiotika.

In order to evaluate quantitatively changes of kidney tubular membrane and lysosomal proteins following administration of aminoglycosides and cephalosporins enzymatic and enzyme histochemical investigations were performed. Alterations of kidney enzyme concentrations of the proximal tubule were considered as a parameter indicating nephrotoxic and inductive effects of antibiotics. Following administration of aminoglycosides to volunteers significantly (Wilcoxon test, 2P less than 0.05) increased enzymuria was found as compared to untreated control persons. Under experimental conditions inductive effects were analysed following treatment with aminoglycosides, especially gentamicin. In contrary to these findings cephalosporins were administered without effects an the proximal tubule. Once daily administration of aminoglycosides were observed to be less nephrotoxic than twice daily injections to volunteers. Quantitative evaluation of tubular specific proteins appears to be a tool in monitoring the degree of alterations (enzyme induction, -liberation, -excretion) caused by antibiotics.

Digital templating in hip replacement with and without radiological markers.

Digital templating in hip replacement is commonly performed with radiological markers to determine the magnification. The latter can also be determined by measuring the distance from the x-ray focal spot to the object and the distance from the x-ray focal spot to the radiological cassette or image receptor. We used post-operative radiographs of total hip replacements and hemiarthroplasties from 22 patients to calculate the magnification using both methods. The accuracy of each method was ascertained by measuring the size of the head of the implant projected on to the radiographs and comparing the result with the known size recorded in the medical records. The accuracy was found to be similar with a mean absolute measurement error of 2.6% (SD 1.4; 0.0% to 5.2%) for the radiological marker and 2.8% (sd 2.2; 0.4% to 10.1%) for the distance method (p = 0.75). The mean radiation dose for templating radiographs (pelvis and lateral of the hip) was similar when taken using a radiological marker (328 mSv SD 142) (n = 51) or using the distance measurement method (324 mSv SD 39) (n = 39) (p = 0.90). We conclude that the distance measuring method is as accurate as the radiological marker method, but may avoid some of the disadvantages such as misplacement of the marker or placement outside the radiological field. It may also be more acceptable to the patient and radiographer.

Pressure sores and hip fractures.

Development of pressure sores during hospital admission causes morbidity and distress to the patient, increases strain on nursing resources, delaying discharge and possibly increasing mortality. A hip fracture in elderly patients is a known high-risk factor for development of pressure sores. We aimed to determine the current incidence of pressure sores and identify those factors which were associated with an increased risk of pressure sores. We retrospectively analysed prospectively collected data of 4654 consecutive patients admitted to a single unit. One hundred and seventy-eight (3.8%) of our patients developed pressure sores. Patient factors that increased the risk of pressure sores were increased age, diabetes mellitus, a lower mental test score, a lower mobility score, a higher ASA score, lower admission haemoglobin and an intra-operative drop in blood pressure. The risk was higher in patients with an extracapsular neck of femur fracture and patients with an increased time interval between admission to hospital and surgery. Our studies indicate that while co-morbidities constitute a substantial risk in an elderly population, the increase in incidence of pressure sores can be reduced by minimising delays to surgery.

Intramedullary osteosynthesis of complex proximal femoral fractures with the Targon PF nail.

We evaluated the performance of the Targon PF nailing system in the treatment of complex proximal femoral fractures with a retrospective analysis of prospectively collected data for 94 patients with a complex proximal femoral fracture (subtrochanteric fracture or fracture with reversed fracture line pattern) treated with a Targon PF nail. There were no intra-operative femoral fractures. Late complications requiring reoperation were one femoral fracture and one fracture around the nail secondary to tumour. Seven nails had to be dynamised and a further six 'self-dynamised' at the site of the distal locking screw. One patient required revision of the distal locking. Only one other patient required secondary surgery for a wound haematoma. There were no cases of implant cut-out or non-union. The Targon PF nail represents a progressive development in the design of intramedullary nails for proximal femoral fractures and the results compare favourably with other intramedullary systems used to treat complex proximal femoral fractures.

[Retrograde infusion urethrocystography in boys]. / Retrograde Infusionsurethrozystographie beim Knaben.

The main advantages of retrograde infusion-urethrocystography are compared with conventional diagnostic procedures: a sterile infusion set is used for small anatomic situations in the childs urethra; the radiological evaluation of the urethra can be performed painlessly, non invasively, and avoids radiation of the investigator as shown by the examination of 35 young patients in our department.

Quantitative enzymatic and immunologic computer-assisted histophotometry of human kidney tissue following neoplastic and other clinically significant alterations.

Renal tissue sections from 178 patients, whose kidneys were either normal or altered by various conditions such as hydronephrosis, interstitial nephropathies, chronic graft rejection, renal cancer etc., were investigated by computer-assisted histophotometry. We used enzyme histochemical and immunologic methods to measure kidneys suffering from various urological diseases quantitatively. Through this procedure, we were able to obtain information that allowed us to determine the degree of alteration in the metabolic state of tubular epithelial cells. The tissue activities of the following enzymes of the proximal tubule were investigated: alanine aminopeptidase (AAP), alkaline phosphatase (AP) and maltase (Ma) as membrane-bound markers, and beta-glucuronidase (beta-Gl) as a lysosomal marker. In addition, AAP and gamma-glutamyltranspeptidase (GGTP) were measured by immunofluorescent microscopy after having added specific anti-enzyme antibodies to the tissue sections. Compared to normal kidneys, quantitative enzyme histograms of diseased kidneys revealed a significant decrease in marker protein concentration of the tubule. The decline in tissue enzyme activities of AP, AAP, Ma and beta-Gl was accompanied by a significant decrease of enzyme concentrations as measured by the immuno histological method. This was especially true in cases with kidney cancer and in kidney tissues adjacent to infiltration adenocarcinoma. Morphological analyses of alterations were generally improved by enzymatic and/or immunologic histophotometry.

Surgery for recurrent goitre: its complications and their risk factors.

OBJECTIVE: To find out the morbidity of reoperation for benign recurrent thyroid disease, and the risk factors associated with it. DESIGN: Retrospective study. SETTING: Specialist endocrine unit, Germany. SUBJECTS: 1031 patients operated on for recurrent goitre between 1 January 1983 and 31 December 1996. MAIN OUTCOME MEASURES: Incidence of recurrent laryngeal nerve palsy and hypocalcaemia. RESULTS: 82/1031 patients were excluded from assessment for recurrent laryngeal nerve function leaving 949 for analysis. There were no cases of bilateral permanent palsy, but 1 patient developed temporary bilateral palsy. 33 patients (3%) developed permanent unilateral palsy and 46 (5%) temporary palsy. 1307 nerves were at risk, and the rate of permanent palsy was therefore 2% of nerves at risk. This was 5 times the rate after the initial operation. Hyperthyroidism and not exposing the nerve during operation were predisposing factors. 118 patients were excluded from assessment of hypocalcaemia leaving 913 for analysis. 23 patients developed temporary hypocalcaemia (2%), but only 5 (0.5%) developed permanent hypocalcaemia. Because so few patients developed hypocalcaemia we were unable to designate risk factors. CONCLUSION: Because of the high risk of complications operations for recurrent goitre should be done only if the patient cannot be treated in any other way. The risk of recurrence should be minimised by excision of all nodules during the initial operation.

Nitric oxide and prostaglandin pathways interact in the regulation of hypercapnic cerebral vasodilatation.

To test whether nitric oxide and prostaglandin pathways interact in hypercapnic cerebral vasodilatation, cerebral blood flow (CBF) was measured in enflurane anaesthetized Sprague-Dawley rats using the hydrogen clearance method. Isometric tension was measured in rat middle cerebral arteries in vitro. The neuronal NO synthase inhibitor 7-nitroindazole (7-NI 60 mg kg-1 i.p.) reduced the hypercapnic CBF response by 62 +/- 7% (but not the hypoxic response) and indomethacin (IMC 6 mg kg-1 i.v.) reduced the hypercapnic CBF response by 60 +/- 5%. Combined application caused only an 80 +/- 1% reduction. The attenuation of hypercapnic CBF by IMC was diminished by 7-NI and similarly 7-NI had less effect in the presence of IMC. Spermine-NO (50 microM 0.5 microL min-1 intracortically) increased eucapnic and hypercapnic CBF in the presence of IMC. In isolated middle cerebral arteries, combined application of sodium nitroprusside (SNP 3 nM) and prostacyclin (30 nM) had a synergistic vasodilatory effect. Milrinone (PDE-III inhibitor) also potentiated prostacyclin-mediated vasodilatation. Our results suggest that the NO- and IMC-sensitive pathways involved in the hypercapnic response are distinct, however, both may interact synergistically. A similar synergism was observed between the effects of SNP and prostacyclin.

Differential K+ channel distribution in smooth muscle cells isolated from the pulmonary arterial tree of the rat.

Intracellular photorelease of Ca2+ demonstrated the presence of Ca(2+)-activated K+ channels in smooth muscle cells isolated from different locations of the rat pulmonary arterial tree. However, cell-free patch studies revealed marked differences in K+ channel distribution. In the main pulmonary artery the most frequently observed K+ channel was a approximately 245pS conductance Ca(2+)- and ATP-activated (KCa,ATP) channel. In small pulmonary arteries two K+ channel types predominated: the KCa,ATP channel and a approximately 185pS conductance K+ channel insensitive to intracellular Ca2+, ATP and voltage. This difference in K+ channel distribution may highlight a more complex regulatory mechanism for controlling membrane potential in small pulmonary arteries, reflecting their physiologically more important role in governing pulmonary vascular reactivity.

Quantitative histophotometry analysing significant inductive and alterative effects of aminoglycoside application (gentamicin, tobramycin, amikacin) upon tubular kidney proteins.

In order to evaluate quantitative changes in kidney proteins, computer-assisted histophotometry of tissues was performed. Kidney marker enzyme concentrations were considered to be involved in inductive and alterative developments in the proximal tubule. These effects were caused by the administration of aminoglycosides. Indicator enzymes of the proximal tubule such as membrane-bound alkaline phosphatase (AP) and alanine-aminopeptidase (AAP) as well as lysosomal beta-glucuronidase (beta-Gl) were stained in kidney tissues. Graphic monitoring and digital display of kidney cortex sections were registered by electronic image analysis using the 'Micro-Videomat' 2 system. As an experimental design, 160 kidneys of Wistar rats were studied. Their kidneys were analyzed after one, two and three intravenous applications of gentamicin, 25 mg/kg/day, or tobramycin, 25 mg/kg/day, or amikacin, 50 mg/kg/day, on consecutive days. In a fourth test group, the kidneys were examined after the third application and a 5-day recovery period. Concentrations of tubular marker enzymes were significantly increased (2p less than 0.01, Wilcoxon test) after two applications of gentamicin: AP 37.6%, AAP 6.3% and beta-Gl 11.8%. Contrary to these findings, after two injections of tobramycin or amikacin only slight alterations were documented: tobramycin, AP 14.5%, AAP -0.1% and beta-Gl 0.4%; amikacin, AP 6.0% and AAP 4.2%. The studies indicate that tobramycin induces less severe nephrotoxic and inductive reaction than gentamicin and partly than amikacin in doses administered during our experiments. In all cases, enzyme activities studied were nearly normalized after three applications of aminoglycosides and a recovery period of 5 days. Quantitative computer-assisted evaluation of the proteins located in the tubule appears to be a tool for monitoring the degree of alterations caused by enzyme induction, enzyme release and excretion of kidney proteins.

Quantitative enzymatic histophotometry of morphologic alterations caused by urologically relevant tubular kidney damages using computed image analysis device technique.

The tissue concentration of tubular marker enzymes were evaluated in sections of kidneys from 86 patients with various underlying diseases such as hydronephrosis, interstitial nephropathies, ischemia due to renal arterial stenosis and chronic allograft rejection. In addition, as an experimental model, kidney tissue sections of 166 Wistar rats were analyzed due to hydronephrosis caused by ureteral obstruction, ischemia and obstruction of the renal vein. The tissue concentration of indicator enzymes, such as alkaline phosphatase (AP) and alanine-aminopeptidase (AAP), was considered as a parameter describing the extent of kidney tubule damage. Quantitative evaluation of enzymatic activity was performed by histophotometry using a computed image analysis device technique. As compared to normal human kidney (enzyme activity 100%), the concentrations of brush border enzymes were significantly (p less than 0.001) lower under pathological conditions (AP less than 15%, AAP less than 55%). In similar manner investigations of kidneys in animal experiments with rats exhibited lower enzyme concentrations following kidney injury caused by ureteral obstruction for 10 and 21 days (AP less than 12%, AAP less than 65%; 2p less than 0.01). Kidneys after an ischemic period of 2 h and a subsequent 14-day recirculation period displayed a significant (2p less than 0.01) decrease of normally present indicator enzyme concentrations (AP less than 22%, AAP less than 77%) as compared to normal renal organs (100%). Computed image analysis of kidney tissue sections might be a useful aid in evaluating morphologic and enzymatic patterns of human and animal kidney alterations.

Quantitative enzymatic, immunologic and histochemical studies of clinically relevant human kidney alterations using image analysis.

Tissue sections of kidneys from 172 patients with various pathologic conditions, such as hydronephrosis, interstitial nephropathies, ischemia, chronic graft rejection and renal cancer, were evaluated by an image analysis technique. Structurally defined kidney alterations were monitored for enzymatic, immunologic and other histochemical changes. Indicator enzymes of the proximal tubule, alanine-aminopeptidase (AAP), alkaline phosphatase (AP), beta-glucoronidase (beta-Gl) and gamma-glutamyltranspeptidase (GGTP), were used as parameters for screening. Enzyme concentrations were found to be significantly decreased in kidney sections of patients with various renal diseases (AP less than 15%, AAP less than 55% and beta-Gl less than 60%) as compared to normal kidney tissues (100%). AAP concentration was measured quantitatively by specific immunofluorescence using an antienzyme antibody. Immunofluorescence of AAP was comparable to that of AAP calculated by the colorimetric technique (substrate: DL-alanine-beta-naphthylamide-HCl) and decreased to less than 50% in altered kidney tissues. Furthermore, kidney cancer (less than 20%) and kidney tissue adjacent to tumours (less than 65%) displayed significantly decreased levels of kidney marker enzyme activity. This study suggests that (1) the diseased kidney is characterized by a defined change in key enzymes of the cell surface and (2) renal cancer exhibits partial depletion of these constituents. Image analysis of the pattern of enzyme activity appears to be a useful tool in the analysis of renal pathology.

Enzymuria: a parameter for the assessment of potential nephrotoxicity of cephalosporins.

Ten informed healthy volunteers with normal renal function received 2 X 3.0 g ceftazidime on three consecutive days. The combination of the same dose of ceftazidime together with tobramycin (3 mg/kg/d) was administered four weeks later to the same group of volunteers. In the first trial with ceftazidime alone no changes in the elimination of brush-border membrane enzyme AAP were found. In contrast, the administration of ceftazidime together with tobramycin produced the expected response to tobramycin with the cumulative pattern of enzyme elimination into urine. Functional parameters remained unchanged.