The reliability of diagnosis of infection during revision arthroplasties.

BACKGROUND: Follow up studies have shown that 0.5 to 4% of the total joint arthroplasties will be complicated by infection. Distinction between aseptic loosening and infection is important for prediction of the final outcome after revision arhtroplasty but also for the choice of operative treatment. However, diagnosis of low grade chronic infection is extremely demanding. MATERIALS AND METHODS: 68 hip and knee revision arthroplasties were reviewed retrospectively in order to evaluate the reliability of pre- and perioperative analysis of infection during total joint revision arthroplasties. The sensitivity and specificity for clinical signs, blood white-cell count, C-reactive protein level, radiographic analysis, bone and leukocyte scans, joint aspirations, and gram staining were determined. Tissue sample were harvested and cultured in all cases. Positive cultures were regarded as a true infection. RESULTS: We were not able to characterize the infection by clinical signs. Also no single test was able to show the presence of infection in all cases. The best results were obtained from pre- and perioperative joint aspirations. Joint aspiration showed 1.0 specificity and 0.75 sensitivity. CONCLUSION: It is clear from this study that no single test is able to show the presence of infection in every case. Classical clinical signs, laboratory tests, special imaging studies and joint aspirations have all yielded a notable rate of false negative results. Therefore, we recommend that, if arthroplasty patients have pain in prosthetic joint without clear radiological evidence of loosening, bone scans and preoperative joint aspirations should be undertaken. Also, if radiological evidence of loosening is accompanied with one or more of following criteria; C-reactive protein level elevated, radiologic evidence of infection, loosening within the first five years after implantation. In case of infection a delayed two-stage reconstruction should be managed.

Comparison of the analgesic effects of intrabursal oxycodone and bupivacaine after acromioplasty.

STUDY OBJECTIVES: To compare the peripheral analgesic effect of oxycodone, an opioid agonist, to the effect of bupivacaine infiltration and parenteral oxycodone administration in conjunction with shoulder surgery. DESIGN: Prospective, randomized, double-blind study. SETTING: University teaching hospital. PATIENTS: 42 ASA physical status I and II patients scheduled for shoulder surgery with general anesthesia. INTERVENTIONS: Patients were randomized to three study groups: at the end of the surgery patients received either 10 ml of 0.5% bupivacaine (group BIB) or 5 mg of oxycodone in 10 ml of saline (group OIB) in the subacromial bursa; or 5 mg of oxycodone intramuscularly (group OIM). Postoperative analgesia was provided by patient-controlled analgesia (PCA). MEASUREMENTS AND MAIN RESULTS: The fentanyl requirements were recorded for the 24-hour postoperative period and the total perioperative period. Postoperative pain was assessed by visual analog scale for pain (VASP). Plasma oxycodone concentrations were measured in groups OIB and OIM. The total perioperative fentanyl consumption was significantly lower in groups BIB (0.97 +/- 0.09 mg) and OIB (1.23 +/- 0.12 mg) than in group OIM (1.61 +/- 0.12 mg) (p = 0.01 and 0.048, respectively). Groups BIB and OIB were similar (p = 0.34). The absorption of oxycodone was significantly lower after subacromial than after intramuscular administration. CONCLUSION: Intrabursal oxycodone and intrabursal bupivacaine reduced perioperative analgesic requirements similarly. Intrabursal oxycodone may offer an effective, simple, and safe method for postoperative analgesia after shoulder surgery.

Effect of Elmslie-Trillat and Roux-Goldthwait procedures on patellofemoral relationships and symptoms in patients with patellar dislocations.

Seventeen patients (18 knees) with a history of one or more patellar dislocations underwent Elmslie-Trillat (9 knees [group 1]) or Roux-Goldthwait (9 knees [group 2]) patellar realignment surgery. Anterior knee pain was evaluated with a questionnaire, and lateral patellar displacement and tilt were analyzed by magnetic resonance imaging both pre- and postoperatively. Postoperative evaluations were performed after 44 and 50 months (mean) in groups 1 and 2, respectively. The Elmslie-Trillat procedure provided better subjective relief of anterior knee pain and symptoms. One redislocation occurred in each group. Both procedures relieved excessive patellar lateralization, but the effect on patellar tilt was less marked. In patients who underwent the Roux-Goldthwait operation, a less pronounced correction of tilt and lateralization appeared to correlate with more satisfactory subjective results.

Experimental fat embolism induces urine 2,3-dinor-6-ketoprostaglandin F1alpha and 11-dehydrothromboxane B2 excretion in pigs.

OBJECTIVE: To evaluate the in vivo production of prostacyclin and thromboxane A2 during the initial phase of experimental fat embolism as assessed, respectively, by determinations of urine 2,3-dinor-6-ketoprostaglandin F1alpha and 11-dehydrothromboxane B2 excretion. DESIGN: Randomized, controlled trial. SETTING: Animal laboratory. SUBJECTS: Twenty seven domestic pigs, weighing 24 to 31 kg. INTERVENTIONS: All pigs were anesthetized and mechanically ventilated during the experiment. Eighteen pigs were subjected to an intracaval infusion of 10% allogeneic bone marrow suspension at a dose of 100 mg/kg over 5 mins. Nine pigs received only bone marrow suspension (fat embolism group). Nine pigs were given an intravenous bolus of aspirin (300 mg) 1 hr before the bone marrow suspension infusion. After the induction of fat embolism, intravenous aspirin was administered at a dose of 150 mg/hr for 2 hrs (aspirin-treated group). Nine pigs were infused with saline (control group). MEASUREMENTS AND MAIN RESULTS: In the fat embolism group, cardiac index decreased within 30 mins, while mean arterial pressure remained unchanged. Central venous pressure and pulmonary artery occlusion pressure remained relatively stable over time in the animals with fat embolism. Mean pulmonary arterial pressure and pulmonary vascular resistance increased immediately after the bone marrow suspension infusion from 23 +/- 0.8 (SEM) to 34 +/- 1.3 mm Hg and from 305 +/- 28 to 585 +/- 45 dyne x sec/cm5, respectively; these variables remained increased throughout the study period. Simultaneously, pulmonary shunt in the fat embolism group increased persistently from the baseline of 12.3 +/- 2.8%, and reached its maximum of 26.1 +/- 4.8% at the end of the experiment. Instant and gradual decreases in PaO2 (from 95 +/- 4 to 67 +/- 5 torr [12.6 +/- 0.5 to 8.9 +/- 0.7 kPa]), hemoglobin oxygen saturation (from 97.2 +/- 0.4 to 91.8 +/- 1.8%), and oxygen delivery (from 16.3 +/- 1.0 to 12.6 +/- 0.4 mL/min/kg) were observed in the fat embolism group. In the bone marrow suspension-infused animals, urine 2,3-dinor-6-ketoprostaglandin F1alpha excretion increased transiently from 451 +/- 63 up to 1466 +/- 499 pg/micromol creatinine, while urine 11-dehydrothromboxane B2 excretion increased transiently from 385 +/- 36 up to 2307 +/- 685 pg/micromol creatinine. In the aspirin-treated animals, urinary excretion of these prostanoid metabolites was reduced by 81% and 88%, respectively. The changes in mean pulmonary arterial pressure and PaO2 were ameliorated, and the alterations in pulmonary shunt and SaO2 were abolished in the animals with aspirin treatment. CONCLUSIONS: Pulmonary hypertension, increased pulmonary vascular tone, and increased pulmonary shunt are hallmarks of the present fat embolism model. These hemodynamic responses may, at least partly, be related to the changed balance between prostacyclin and thromboxane A2 production.

Catalytic activity of phospholipase A2 in serum in experimental fat embolism in pigs.

OBJECTIVE: To investigate the catalytic activity of phospholipase A2 in serum during the early phase of experimental fat embolism. DESIGN: Randomised controlled experimental study. SETTING: Animal laboratory, Finland. SUBJECTS: 18 domestic pigs weighing 25-31 kg. INTERVENTIONS: Allogeneic bone marrow suspension at a dose of 100 mg/kg was infused intracavally in 9 anaesthetised, mechanically ventilated, and haemodynamically monitored pigs; 9 control pigs received saline. MAIN OUTCOME MEASURES: Central haemodynamics, blood gases, catalytic activity of phospholipase A2. RESULTS: In the fat embolism group, there were significant increases in mean pulmonary arterial pressure (p < 0.001), pulmonary vascular resistance (p < 0.001) and pulmonary shunting (p < 0.05) and simultaneously, systemic oxygenation was significantly impaired. The animals with fat embolism developed gradual fever and leucocytosis, whereas the catalytic activity of phospholipase A2 remained relatively unchanged. CONCLUSION: In this experimental model the measurement of serum phospholipase A2 activity does not provide a useful tool for the early detection of experimental fat embolism.

Plasma levels of atrial natriuretic peptide and endothelin-1 in experimental fat embolism.

In order to understand the role of vasoactive peptides in fat embolism, arterial plasma atrial natriuretic peptide (ANP) and endothelin-1 concentrations were investigated in an experimental study. Nine anesthetized and mechanically ventilated pigs received an intracaval infusion of allogeneic bone marrow suspension at a dose of 100 mg/kg (fat embolism group); 9 control pigs received saline. The observation period was 5 h. In the fat embolism group, cardiac index and heart rate decreased within 30 min, whereas mean arterial pressure remained stationary. Pulmonary capillary wedge pressure rose transiently and central venous pressure rose slightly in time, while mean pulmonary arterial pressure, pulmonary vascular resistance and pulmonary shunt increased immediately and persistently after the bone marrow suspension infusion. Simultaneously, arterial oxygen tension and arterial hemoglobin oxygen saturation decreased markedly. Arterial plasma ANP and endothelin-1 concentrations remained stable in the fat embolism animals, whereas in the controls ANP and endothelin-1 levels decreased at 3 and 5 h. Arterial epinephrine concentrations were stable in animals receiving bone marrow suspension, while in the controls arterial epinephrine concentrations decreased towards the end of the experiment. Arterial norepinephrine concentrations remained unchanged in both groups. To conclude, impaired pulmonary function and consequent systemic hypoxemia distinguish the present fat embolism model. Unchanged arterial ANP and endothelin-1 concentrations in the fat embolism group suggest that these circulating vasoactive hormones have a minor impact on the pathogenesis of the current experimental fat embolism.

Splanchnic and peripheral tissue perfusion in experimental fat embolism.

OBJECTIVE: To investigate the acute effects of experimental fat embolism on splanchnic and peripheral perfusion and oxygenation in pigs. DESIGN: Randomized, controlled trial. SETTING: Animal laboratory. SUBJECTS: Eighteen domestic pigs, weighing 25 to 31 kg. INTERVENTIONS: The 18 pigs were randomized to either the fat embolism or control groups. Nine anesthetized and mechanically ventilated pigs were intracavally infused with a 10% allogeneic bone marrow suspension at a dose of 100 mg/kg over 5 mins (the fat embolism group); nine control pigs received normal saline in the same volume and speed (control group). MEASUREMENTS AND MAIN RESULTS: Mean pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary shunt increased, and PaO2 decreased immediately after the bone marrow suspension infusion. In the fat embolism animals, oxygen delivery decreased, oxygen content difference widened, and total oxygen consumption remained high, indicating enhanced oxygen extraction. Further, superior mesenteric artery blood flow and mesenteric oxygen delivery decreased, while intramucosal pH in the small bowel was stable. Subcutaneous PO2 decreased in both groups, whereas transcutaneous PO2 decreased only in the animals receiving bone marrow suspension. Skin red cell flux showed no significant changes. CONCLUSIONS: The present model of fat embolism results in significant impairment in systemic oxygenation. Despite this fact, the intestinal oxygenation remains unaffected probably due to sufficient compensatory mechanisms. Transcutaneous PO2 measurements may provide a useful index for early detection of fat embolism.

Effects of experimental fat embolism on central hemodynamics and oxygenation in pigs.

Nine anesthetized and mechanically ventilated test pigs were intracavally infused with a 10% allogeneic bone marrows suspension at a dose of 100 mg/kg over 5 min; 9 control pigs received saline. The cardiac index decreased slightly in the fat embolism animals. Left ventricular stroke work remained unchanged in both groups, whereas right ventricular stroke work rose in the fat embolism animals. Mean arterial pressure remained stationary in the test group but rose in the controls. Pulmonary capillary wedge pressure and central venous pressure rose slightly in the test group. After infusion of the bone marrow suspension, mean pulmonary arterial pressure, pulmonary vascular resistance, pulmonary shunt and alveoloarterial oxygen tension difference increased immediately and remained elevated throughout the study period. Simultaneously, arterial and mixed venous oxygen tension and hemoglobin oxygen saturation decreased. Arterial carbon dioxide tension and hematocrit remained stationary. The fat embolism animals developed gradual fever. In conclusion, increased mean pulmonary arterial pressure, pulmonary vascular resistance, pulmonary shunt and alveoloarterial oxygen tension difference proved to be useful early indicators of experimental fat embolism.

Magnetic resonance imaging of patellofemoral relationships.

Patellofemoral relationships were analyzed in 11 patients (13 knees) with patellar dislocation and 15 asymptomatic subjects (15 knees) at 0 degree and 20 degrees of flexion. The measurements were made from five consecutive axial images through the patellofemoral joint. The six indices measured were lateral patellar tilt (LPT), lateral patellofemoral angle (LPA), lateral patellar displacement (LPD), patella-lateral condyle index (L/PW), congruence angle (CA), and sulcus angle (SA). The reproducibility of the method was evaluated. The difference between the two study groups was more evident at 0 degree than at 20 degrees of knee flexion. Significant differences were noted between measurements made at different levels of the joint, particularly in the controls. Isometric contraction of the quadriceps muscle lateralized and tilted the patella slightly in both groups. L/PW with and without quadriceps muscle contraction, and LPA with reference to the anterior condyles differentiated between the two study groups most clearly. LPT and LPA with reference to the anterior condyles differentiated the study groups better than LPT and LPA with reference to the posterior condyles. The reproducibility was good except for inter-observer comparison of CA and SA. The use of an imaging plane selected at the midpoint of the patellar articular cartilage increases the sensitivity of the measurements, since it takes into account both the height of the patella and the tendency towards lateralization. These results indicate that patellar tilt is best measured with the LPA index and patellar lateralization with the L/PW index at 0 degree knee flexion. This study should always include isometric contraction of the quadriceps muscle.

Scoring of patellofemoral disorders.

A new questionnaire was used to evaluate subjective symptoms and functional limitations in patellofemoral disorders. The questionnaire was completed independently by four groups of female subjects: controls (N = 17), and subjects with anterior knee pain (N = 16), patellar subluxation (N = 16), and patellar dislocation (N = 19). The questionnaire mean scores for the groups were 100, 83, 68, and 62 points, respectively (p < 0.0001). The items dealing with abnormal painful patellar movements (subluxations) (p < 0.0001), limp (p < 0.0001), pain (p < 0.0001), running (p < 0.0001), climbing stairs (p < 0.0001), and prolonged sitting with the knees flexed (p < 0.0001) differentiated the study groups most clearly. We recommend that these questions be asked when taking a standardized clinical history of an anterior knee pain patient. We also analyzed lateral patellar tilt and displacement by magnetic resonance imaging (MRI) in 28 subjects with patellar subluxation or dislocation. Low questionnaire sum score correlated best with increased lateral patellar tilt measured during quadriceps contraction in 0 degree knee flexion. It seems that a tendency to lateral patellar tilt during quadriceps contraction causes anterior knee pain and can be imaged in knee extension when the patella is not fully supported by femoral condyles.

ABO blood groups and musculoskeletal injuries.

The distribution of the ABO blood groups was studied in 917 patients with specific musculoskeletal diagnoses. The ABO blood group distribution of patients with rupture of the Achilles tendon (P = 0.030) and of patients with chronic Achilles peritendinitis (P = 0.10) differed from the controls. The ABO blood group distribution was not associated with other musculoskeletal injuries studied. The blood group A/O ratio was 1.42 in the control population. In the group with rupture of the Achilles tendon this ratio was 1.0, and in the group with Achilles peritendinitis it was 0.70. The association between injuries of the Achilles tendon and the ABO blood group distribution was in accordance with an earlier report. There may be a genetic linkage between the ABO blood groups and the molecular structure of the tissue of Achilles tendons.

Relationship between the pivot shift and the configuration of the lateral tibial plateau.

Twenty patients with a chronic anterior cruciate ligament tear were studied. First they were interviewed on the preoperative history of unexpected giving way (pivot shift), then they were tested for clinical pivot shift sign, and last, the configuration of the lateral tibial plateau was studied using magnetic resonance imaging. A connection could be noticed between the history of instability symptoms and the pivot shift sign at clinical examination (P less than 0.001). Interestingly, there was also a link between the instability history and the configuration of the lateral tibial plateau (P = 0.0021), and, further, between the clinical pivot shift sign and the configuration of the lateral tibial plateau (P = 0.0002). The variation in the shape of the convexity of the lateral tibial plateau seems to be associated with the symptoms and prognosis of the patients with rupture of the anterior cruciate ligament.

Renal carnitine concentration decreases in endotoxic dogs.

BACKGROUND AND METHODS: Renal cortical and serum carnitine concentrations were studied in seven anesthetized beagle dogs in which acute circulatory collapse was induced by an iv injection of Escherichia coli endotoxin, 0.5 mg/kg given over 15 mins. Four controls received normal saline. RESULTS: The endotoxin injection resulted in cardiac depression, renal hypoperfusion, acidosis with a decrease in urinary output, and hematuria. Arterial and renal venous free carnitine concentrations increased significantly in endotoxemia during the 5-hr experiment, but remained low and unchanged in the controls. Circulating acyl-carnitine concentrations underwent no essential changes in either group. Total, free, and acyl-carnitine concentrations decreased in endotoxic renal tissue. CONCLUSIONS: These data suggest that endotoxemia decreases carnitine concentrations in the renal cortex, but increases free carnitine concentrations in the circulation.

Renal uptake of fats and glycerol in endotoxin shock in dogs.

Circulatory changes and renal uptake of free fatty acids (FFA), glycerol and triglycerides were studied in ten adult beagle dogs during pentobarbital anesthesia. Six dogs were injected intravenously with E. coli endotoxin 0.5 mg/kg over 15 min and four control dogs received saline. Cardiac depression, hypotension, renal hypoperfusion and acidosis resulted in endotoxin shock. Arterial FFA concentrations increased significantly 2 hours after onset of shock whereas renal venous FFA levels remained rather stationary during the 5-hour study. Arterial and renal venous glycerol levels increased during the first two hours and decreased thereafter. Unchanged triglyceride levels were observed in endotoxin shock. The renal uptake of FFA increased with increasing arterial FFA concentrations. Net renal uptake of glycerol and triglycerides were observed as well. Blood concentrations and renal uptake of fats and glycerol remained relatively stationary in the control animals through the observation period. These data suggest renal ability to consume FFA, glycerol and triglycerides during endotoxin shock.

Plasma levels of atrial natriuretic factor and catecholamines in endotoxin shock in dogs.

Changes in arterial plasma levels of atrial natriuretic factor and catecholamine release were studied in 11 beagle dogs during pentobarbital anesthesia. Seven dogs were injected intravenously with Escherichia coli endotoxin, 0.5 mg/kg over 15 min. Four control dogs received only saline solution. The endotoxin injection resulted in cardiac depression,, hemoconcentration, acidosis and renal hypoperfusion. The central venous pressure remained relatively unchanged in both groups during the 2-hour study. The concentrations of epinephrine, norepinephrine and the norepinephrine metabolite 3,4-dihydroxyphenylglycol increased in arterial plasma during the acute hypodynamic endotoxin shock. In the control dogs the levels of these hormones remained very low and constant. Increased circulating levels of atrial natriuretic factor were observed in endotoxin shock with renal hypoperfusion, unchanged central venous pressure and no concomitant tachycardia.

Patellofemoral relationships in recurrent patellar dislocation.

Magnetic resonance imaging was used to analyse the patellofemoral relationships during the first 30 degrees of knee flexion in women with recurrent patellar dislocation. The patellofemoral joints were imaged both sagittally and axially with the knee flexed 0 degrees, 10 degrees, 20 degrees, and 30 degrees. At the beginning of knee flexion the sulcus angle was greater than in unaffected women, the lateral patellofemoral angle was smaller, the patella displaced further laterally, tilted more laterally and the congruence angle was directed more laterally. At 30 degrees of knee flexion these differences were less marked than at 0 degree to 10 degrees. Logistic regression analysis showed that the sulcus angle at 10 degrees of knee flexion was the most diagnostic feature, indicating that there is an anatomical predisposition to recurrent dislocation and that pathological patellar tracking starts from the beginning of flexion. Traditional sunrise radiographic films taken at 25 degrees to 30 degrees knee flexion clearly miss diagnostically important information.

Renal glucose and lactate metabolism in endotoxin shock in dogs.

Renal metabolism of glucose and lactate was studied in ten adult beagle dogs during pentobarbital anesthesia. Six dogs were submitted to hypodynamic shock by means of an intravenous bolus injection of Escherichia coli endotoxin, 0.5 mg/kg over 15 min. Four dogs received only saline solution and served as controls. Sudden cardiac depression, hypotension and moderate renal hypoperfusion were observed in the endotoxin-injected animals. Acidosis and oliguria also occurred during the 5-hour study. Arterial and renal venous glucose concentration increased transiently during the early phase of endotoxin shock. In the control group glucose levels increased slightly by the end of the experiment. Despite marked hyperlactatemia in the endotoxin group, the arteriovenous lactate difference remained almost unchanged. Renal uptake of lactate and output of glucose were not influenced during the moderate renal hypoperfusion caused by endotoxin.

Renal oxygenation in endotoxin shock in dogs.

Renal hemodynamics and oxygen metabolism were studied in eight adult beagle dogs during shock induced with an iv infusion of Escherichia coli endotoxin. Renal blood flow (RBF) and renal cortical PO2 decreased profoundly during the 15-min endotoxin infusion. RBF increased sharply immediately after cessation of infusion, but soon declined and remained depressed throughout the rest of the 4-h experiment. The renal cortical PO2 remained depressed for approximately 2 h and then gradually increased toward the baseline level. Endotoxin infusion was followed by an increased renal PvO2 and a decreased renal arteriovenous oxygen difference. Renal oxygen consumption declined abruptly during endotoxin infusion, but increased toward the end of the experiment. These results suggest impaired tissue oxygenation and possibly increased oxygen shunting in the kidney during endotoxin shock.

Soleus muscle anomaly in a patient with exertion pain in the ankle. A case report.

A patient with soleus muscle anomaly and symptoms simulating retrocalcanear bursitis or peritendinitis of the Achilles tendon is reported. A soft bulge was observed anteromedially to the Achilles tendon some weeks after the onset of symptoms in soccer training. A clinical diagnosis of retrocalcanear bursitis was made and the patient received physiotherapy and two injections of corticosteroids during six months without pain relief. Due to the continuing symptoms surgery was performed and large mass of the anomalic soleus muscle in the Kager's triangle was removed. At the follow-up the patient was asymptomatic and had resumed his physical exercises and soccer training.