Effect of femoral component rotation and patellar design on patellar forces.

A force transducer attached to the patella was used to measure patellar contact forces after total knee arthroplasty for neutral femoral component position and for 10 degrees internal and external femoral component rotations. Knees were cycled continuously under load from 10 degrees to 110 degrees flexion. Two designs of knee replacement with differing degrees of intrinsic tibiofemoral constraint were studied. Additionally, contact forces for a dome shaped patella and a modified dome shaped patella (a patellar component with a central projection surrounded by a peripheral flat region) were compared. When using the design with relatively high intrinsic tibiofemoral constraint, there were no significant changes in patellar contact forces after axial rotation of the femoral component. When using the design with relatively low intrinsic tibiofemoral constraint and averaging over the range of flexion angles tested, the mediolateral component of the patellar contact force increased approximately 17% after 10 degrees internal rotation compared with neutral rotation, and the normal component of the patellar contact force decreased approximately 8% after a 10 degrees external rotation compared with 10 degrees internal rotation of the femoral component. The inferosuperior component of the patellar shear force, when using the modified dome shaped patellar component, was significantly lower than for the dome shaped patella.

Decreased posterior tibial slope increases strain in the posterior cruciate ligament following total knee arthroplasty.

The purpose of this study was to measure the strain in the posterior cruciate ligament as a function of knee flexion angle and posterior tibial slope following total knee arthroplasty with a posterior cruciate ligament-retaining design. Posterior cruciate ligament strain was measured in seven fresh-frozen cadavers for posterior tibial slopes of 10 degrees, 8 degrees, and 5 degrees. For all three levels of tibial slope tested, strain in the posterior cruciate ligament increased with increasing flexion angle to approximately 100 degrees and then decreased with increasing flexion. The strain measured at 8 degrees posterior tibial slope was greater than that measured at 10 degrees, but the difference was not significant. The strain measured at 5 degrees posterior slope was significantly greater than strain measured at both 8 degrees and 10 degrees. This increased strain may result in altered knee kinematics and reduced range of motion at higher flexion angles.

Pheochromocytoma: a twenty year experience at the University Hospital.

During the past 20 years (1970-90), we had 24 patients with pheochromocytoma: 19 diagnosed clinically and 5 post-mortem. Their ages ranged from 17 to 74 (mean, 43.2 years). Males (n = 14) outnumbered females (n = 10), a 1.41:1 M:F ratio. A majority were symptomatic (95%), with a typical triad of headaches, palpitations and diaphoresis. Most frequent finding was hypertension (95%). It was sustained in 60% and paroxysmal in 35%. In 6 patients (25%) pheochromocytomas were bilateral, all familial. Fifteen were solitary adrenal tumors (63%); 3 (12.5%) were extra-adrenal: 2 intra-abdominal, and 1 cardiac paraganglioma of right atrium. Of 6 familial cases, 4 were associated to Von Hippel-Lindau (VHL) disease, while 2 were multiple endocrine neoplasia (MEN-II) patients. All familial cases were bilateral and in the adrenals. There were no malignancies. Among the 19 clinical cases pre-operative Dx was made by positive urine VMA or catecholamines urine levels: (95 and 100% sensitivity respectively). Preoperative visualization by CT or MRI was done in 62% of the most recent patients. In 5 earlier cases the diagnosis was made post mortem: 3 died of cerebral hemorrhage, 1 with a pons infarct and 1 with congestive heart failure (CHF). There were 2 post-operative deaths and another died 13 years later from thyroid medullary carcinoma. Of the 19 operated, 13 (68%) were cured. Thus pheochromocytomas retain considerable morbidity and some mortality. These rare tumors constitute a clinical diagnostic challenge yet a rewarding therapeutic experience for the alert physician.

Aggressive use of intra-aortic balloon pump and emergency coronary bypass surgery. Enhanced survival in acute evolving MI.

This report describes our experience with prophylactic and therapeutic use of IABPs prior to and following coronary artery bypass grafting (CABG) in 39 patients experiencing acute evolving myocardial infarctions (AEMI). All patients showed objective evidence of coronary thrombosis (contrast angiography) followed by later evidence of streptokinase (SK)-induced restoration of antegrade blood flow in the infarct-related coronary artery (as determined by repeat angiography). In these 39 high-risk patients, 38 survived and were discharged. One patient died (2.6 per cent) on the twelfth postoperative day.

Coronary artery bypass grafting within 24 hours after intracoronary streptokinase thrombolysis.

Little specific information currently exists describing the management of patients with an evolving acute myocardial infarction (AMI) treated with direct intracoronary infusion of streptokinase (SK) followed by emergency coronary artery bypass grafting (CABG). A total of 194 patients with an evolving AMI underwent emergency coronary artery angiography with infusion of SK. Thirty-four of these patients with partial restoration of orthograde blood flow in the infarct-related coronary artery (as determined by clinical and objective evidence of myocardial salvage) were referred for emergency CABG. Problems related to the surgical and anesthetic care of these high-risk patients involved: (1) management of resuscitation of patients with AMI, (2) SK-induced coagulopathy and ongoing thrombolysis, and (3) timely CABG to preserve myocardial salvage. To highlight comparisons of SK-CABG management, data regarding 34 consecutive patients having routine non-SK-CABG surgery were collected simultaneously during the study. Data collected retrospectively included: anesthetic drug summaries, time frame of events from admission to the emergency room until commencing bypass, use of invasive monitoring and hemodynamic assist devices, induction complications, operative complications, coagulation derangements, volume replacement, and blood loss. Results revealed no deaths up to 24 hours postoperatively in the 34 emergency SK-CABG patients, even though complications were frequent intraoperatively. Furthermore, there were no statistically significant differences in SK patients v non-SK patients in blood lost, banked blood and cell saver blood administered, or platelet transfusions. However, in comparison to the non-SK-CABG patients, the SK patients received significantly larger amounts of fresh frozen plasma, cryoprecipitate, and aminocaproic acid.