Biomedical subjects
Publications and source records attributed to D T Reilly.
The case of an 80-year-old woman who sustained occlusion of the external iliac vein by methyl methacrylate cement following total hip arthroplasty is presented. The cement was removed via a pelvic approach without the need for revision of the acetabular cup and led to resolution of her symptoms.
Although the risk of pulmonary embolism or other embolic events associated with total joint arthroplasty have been recorded for some time, to date no direct means of monitoring these events in human arthroplasty have been reported. The authors used transesophageal echocardiography to monitor directly the release of embolic particles into the circulatory system during the course of total knee arthroplasty. The transesophageal echocardiography, in conjunction with intramedullary instrumentation, revealed that showers of embolic particles entered the heart in repeated and unpredictable patterns during the course of conventional intramedullary instrumented total knee procedures. In response to the presence of these embolic showers in the heart, an extramedullary pneumatically positioned system of instrumentation permitting automatic and accurate alignment of the knee with the mechanical axis of the femur has been developed. This new instrumentation establishes proper knee kinematics by semiautomatically determining and maintaining accurate positioning of the femoral component along the mechanical axis of the knee. Qualitative and quantitative monitoring of embolic events using transesophageal echocardiography in conjunction with conventional intramedullary and the new instrumentation suggests that the embolic risk is substantially reduced using the new procedure. Furthermore, the new extramedullary instrumentation was able to align the femoral knee component to within 1 degree of the mechanical axis in an initial series of 25 procedures. Excellent component alignment in conjunction with a substantially reduced quantity of embolic particles in the right heart as seen using transesophageal echocardiography was achieved using the newly developed extramedullary positioning and alignment arm.
Data on disease severity, co-morbidity, and process of care were obtained from the medical records of 356 patients without rheumatoid arthritis undergoing a first unilateral total hip replacement at four teaching hospitals in California and Massachusetts. Socio-demographic characteristics, functional status prior and subsequent to hospitalization, and improvement in health status were measured with a patient questionnaire 12 months after discharge. Completed questionnaires were received from 284 patients, a response rate of 79.8%. The questionnaire was acceptable to patients, reliable, and had good construct validity. The data indicate substantial benefits from hip arthroplasty. As expected, pre-surgical functioning was a strong predictor of outcomes 1 year after surgery. Controlling for pre-surgical functioning, age was not related to outcomes.
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Bone allografts were used to reconstruct deficient acetabular and femoral bone in eighteen patients during two-stage revision of a hip arthroplasty that had failed due to infection. At a mean of 4.2 years after reimplantation, only two patients had had recurrence of the infection. Four patients needed another revision arthroplasty for reasons other than infection. These results suggest that allografts of bone are useful for the reconstruction of osseous deficiencies in carefully selected patients who have a hip arthroplasty after infection. The results do not support the concern that allografts that are used under these circumstances necessarily lead to a high rate of recurrence of infection. However, the long-term results of the use of allografts in hip arthroplasty after infection remain unknown.
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This study compared one dose of cefotetan with three doses of piperacillin as prophylaxis against wound infection in 153 patients undergoing elective colorectal surgery. The patients were randomized into two groups: the first received 2 g cefotetan intravenously with induction of anaesthesia (n = 75), and the second received three doses of 2 g piperacillin (n = 78). Wound infection was defined as the presence of an abscess or discharging pus from the wound. In the cefotetan group there were 14 (19%) wound infections and 13 (17%) in the piperacillin group. There were three septic deaths, one in the cefotetan group and two in the piperacillin group. Both groups were comparable with regard to age, sex, nature of pathology and pre- and perioperative risk factors. No significant haematological or biochemical abnormalities were detected. The only adverse reaction was one patient who had an allergic reaction (rash) to piperacillin. These data suggest that single-dose cefotetan is as effective as triple-dose piperacillin in prophylaxis against infection in elective colorectal surgery.
Infection of a prosthetic graft is one of the most feared complications of vascular surgery. The difficulties of accurate, objective diagnosis are well recognised. We have used III Indium labelled white blood cell scans (InWBC) in two groups: 9 control patients who underwent uncomplicated aortic aneurysm surgery, and 23 patients with suspected graft sepsis. In the control group there was one positive scan in a patient with an inflammatory aneurysm. In the suspected sepsis group, 11 patients subsequently has proven graft sepsis. Nine were correctly predicted by Indium scanning. Ten of 12 patients who did not have proven graft sepsis had negative scans. There was a total of 5 inflammatory aneurysms in the control and suspected sepsis groups, of whom two had positive scans. False positive scans were not present in the early postoperative period i patients without inflammatory aneurysms. In our experience Indium labelled WBC scanning for suspected graft sepsis has a accuracy of 83% a negative predictive value of 83% and a positive predictive value of 82%. These results suggest that Indium white cell labelling techniques which do not involve substantial cross-labelling of platelets are the best objective methods of establishing the presence or absence of graft sepsis.
A simple and non-hazardous technique for intraperitoneal placement of gentamicin beads after excision of an infected prosthetic aortic graft is presented. It has been used successfully in six cases of aortic graft sepsis.
Deep vein thrombosis and pulmonary embolism are significant hazards of surgery, especially in orthopedic procedures. However, the true incidence of these complications is unknown. Many surgeons are now using prophylactic methods to prevent the postoperative occurrence of thromboembolic disease. Pneumatic compression devices are recommended in some instances, especially in cases where increased bleeding could be devastating. Several pharmacologic agents are also used, alone or in combination with pneumatic devices. These include subcutaneous heparin, warfarin, dextran, and aspirin. Each agent has advantages and disadvantages. The US National Institutes of Health (NIH) and numerous ongoing clinical trials are attempting to establish recommendations and guidelines for the use of prophylaxis against postoperative deep vein thrombosis and pulmonary embolism.
Diagnostic imaging is often used to document the progression of healing and diagnose complications in the patient with musculoskeletal trauma. Common types of fixation devices and their complications are discussed. Guidelines for acceptable positioning and alignment are described.
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A consecutive series of 60 percutaneous transluminal angioplasties has been performed in 53 patients with severe peripheral ischaemia over a 4 year period. There were 78 lesions dilated with an initial technical success rate of 78%. Forty-eight lesions were dilated for severe claudication and 30 for rest pain or necrosis. There was a mean followup of 24 months (range 9-56) for the immediately successful angioplasties. When these were analysed according to symptomatic relief, 59% of claudicants with iliac lesions were still improved at 2 years, compared with 86% of those with femoropopliteal lesions. Amongst patients treated for rest pain or necrosis there was a 100% success rate at 2 years for iliac lesions, compared with 49% for femoropopliteal lesions. The overall success of this procedure in this high risk group is reflected by the fact that at 2 years 85% of claudicants and 72% of those with rest pain and necrosis have avoided any further procedure. This encouraging early experience confirms the place of interventional radiology in the management of peripheral vascular disease.
The biomechanics of joints are discussed with regard to the relative motion of the bones controlled by a combination of muscle forces, condylar shape, and ligamentous constraints. The author describes the joint reaction forces that are a result of muscle forces, and provides a detailed description of joint loads to the hip and knee.
As strategies are considered for improving fixation of femoral components in total hip arthroplasty (THA), one is challenged to exceed the standard set by contemporary cement procedures. However, despite the improved ten- to 15-year clinical results anticipated with current cementing techniques, the limited fatigue strength of polymethylmethacrylate warrants continued investigation of alternative systems, particularly for younger patients and in revision arthroplasty. Design considerations for femoral stems for cementless THA include (1) initial mechanical stability afforded by the stem shape, (2) strength and stiffness of the stem, and (3) surface features relating to biocompatibility and attachment to bone. In one approach a fit-and-fill algorithm has been implemented to design stems that maximize contact between prosthesis and cortex in priority areas to achieve stability. Titanium is recommended for the fabrication of such stems because of its corrosion resistance, its biocompatibility, and its modulus, which is lower than that of cobalt-chromium alloy. Long-term fixation of these implants will be dependent upon the maintenance of normal strain patterns in the host bone. Achievement of this goal will require additional strategies that combine optimal fit and optimal material properties of the prosthesis.