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The right atrium and the right ventricle of fifty-five patients were imaged with transesophageal echocardiography during fifty-nine total knee arthroplasties performed with cement and the use of general anesthesia. The patients ranged in age from thirty-two to eighty-three years (mean, 65.5 years). Cardiopulmonary parameters were measured with use of hemodynamic monitoring systems, such as pulse oximeters, pulmonary artery catheters, and radial artery catheters. In addition, a femoral vein catheter was inserted on the side of the operation in ten of the fifty-five patients. Showers of echogenic material traversing the right atrium, the right ventricle, and the pulmonary artery after the tourniquet was deflated were observed to various degrees in all patients and lasted three to fifteen minutes. The mean peak intensity occurred within thirty seconds (range, twenty-four to forty-five seconds) after the tourniquet was released. The mean mixed venous oxygen saturation (and standard error of the mean) decreased (from 83+/-0.9 to 72+/-1.5 per cent) and the mean pulmonary arterial pressure increased (from 20+/-1.0 to 27+/-1.0 millimeters of mercury [2.67+/-0.13 to 3.60+/-0.13 kilopascals]), compared with the values before the tourniquet was released, in all patients. The pulmonary vascular resistance index increased after release of the tourniquet (to a maximum of 328+/-29 dyne.s.cm(-5).m2; p = 0.00002) only in the patients who had echogenic material that was at least 0.5 centimeter in diameter. Clinical pulmonary embolism developed postoperatively in three patients; all three had had echogenic particles that were more than 0.5 centimeter in maximum diameter on imaging. Blood aspirated from one of the pulmonary artery catheters and from five of the ten femoral vein catheters demonstrated fresh venous thrombus. Histological evaluation of the aspirates failed to demonstrate fat, marrow, or particles of polymethylmethacrylate. Surgeons should consider acute pulmonary embolism as a diagnosis when evaluating a patient who has hemodynamic collapse during total knee arthroplasty performed with cement.

Using a gait mat, we characterized the functional results for thirty-five patients before and after a total knee replacement for the treatment of degenerative arthritis. Preoperatively, we studied three distinct populations of patients. Group I consisted of sixteen patients who were scheduled to have a unilateral total knee replacement and who had no signs or symptoms of arthritis in the contralateral knee. Group II consisted of twelve patients who were scheduled to have a unilateral total knee replacement but who had asymptomatic degenerative arthritis in the contralateral knee. Group III consisted of seven patients who had bilateral arthritis that was to be managed by total knee replacement. The gait mat allowed us to measure stance time, step length, double-support time, swing time, swing-to-stance ratio, and velocity. A knee-rating scale was used to measure pain. The data were compared with those obtained from an age-matched control group of ninety-one subjects. Postoperatively, the gait evaluation revealed marked improvement in all of the patients. However, the patients in Group II did not improve as much as those in Groups I and III did. We concluded that even asymptomatic arthritis can impair gait, that bilateral total knee replacement can yield excellent results, and that patients tend to use the lower limbs in as symmetrical a way as possible. Gait analysis can be an important source of objective information, and it is easily performed by using a gait mat.