Biomedical subjects

F J Dorey

Publications and source records attributed to F J Dorey.

At least 73 records · Page 4Linked to original sources

PubMed1991

Total knee arthroplasty in patients after patellectomy.

Twenty-six total knee arthroplasties (TKAs) were evaluated in 22 patients who had had a patellectomy. Fourteen knees (12 patients) had a primary TKA, and 12 patients had a revision TKA. Two patients in the revision group, whose prostheses failed, were from the primary TKA group. The mean follow-up time was 8.5 years in the primary TKA group and 7.6 years in the revision TKA group. A group of 14 control knees with patellae was randomly generated but matched for prosthesis, diagnosis, surgeon, age, and time of surgery. This group was similarly evaluated with an average follow-up time of 6.9 years. The primary TKA group had seven knees that were rated as good or excellent, two as fair, and three as poor. The control group had a significantly higher average rating than the primary TKA group. In this group, there were 12 good or excellent knees, three fair, and none poor. Postoperative pain, flexion contracture, extension lag, and range of motion all contributed significant information to the final score, whereas other variables (walking, function, strength, and instability) did not contribute any additional information. Although higher overall scores may have been expected if the patients had patellae, the results during the follow-up examination were satisfactory and justified TKA in these patients. In general, however, patients without patellae may be at a higher risk for failure of the prosthesis, as seen in five patients having primary TKA and another ten patients with failed TKA requiring revision.

Adult↗

PubMed1991

Continuous passive motion versus immobilization. The effect on posttraumatic joint stiffness.

Management of intraarticular fractures is often complicated by joint stiffness long after bony healing has occurred. The following experiments provide biomechanical evidence for the effectiveness of CPM in maintaining joint function in stabilized articular injuries. The ankles of ten adolescent New Zealand white rabbits were penetrated by Steinmann pins to create an intraarticular injury. One limb of each animal was immobilized, and the contralateral limb was placed in a continuous passive motion (CPM) machine for three weeks. Joint stiffness of each ankle was quantified with an arthrograph before injury and after three weeks of treatment. Hindlimb volumes were recorded before injury and monitored at weekly intervals using a water-displacement method. Joint stiffness increased 2.6 times the preinjury levels in limbs that were immobilized for three weeks. There was no statistically significant increase in joint stiffness in ankles treated with CPM compared to preinjury values. The posttraumatic difference between the CPM-treated and immobilized limbs was highly significant; limb swelling was not affected by CPM.

Animals↗

PubMed1990

Correlation between penile angiography and duplex scanning of cavernous arteries in impotent men.

During the diagnostic evaluation of patients with vasculogenic impotence duplex scanning has been proposed as a reliable noninvasive method to evaluate the cavernous arteries. However, the sensitivity and specificity of this test have never been elucidated. To provide insight into the clinical value of this test 25 men who presented with impotence and failed to respond to 60 mg. intracavernous papaverine were evaluated with duplex scanning and the results of this modality were compared to penile angiography. The cavernous arteries were considered normal by duplex scanning if the artery demonstrated either a 60% or greater increase in diameter and/or a peak flow velocity of greater than 25 cm. per second 5 minutes after papaverine injection. Penile angiography was considered normal if both cavernous arteries were visualized and appeared to be normal radiographically (after intracorporeal papaverine). In the 25 patients studied there was no significant difference in peak flow velocity between patients with normal or abnormal cavernous arteries by angiography. In addition, arterial dilatation (more than 60%) after papaverine injection did not correlate with the results of the angiogram. These data demonstrate that duplex scanning of the cavernous arteries does not correlate well with what is observed by penile angiography in a selected population of men with vasculogenic erectile dysfunction. Since penile angiography itself has limitations in the evaluation of the penile arteries, the reliability of duplex scanning to identify cavernous artery dysfunction needs additional confirmation.

Adult↗

PubMed1990

Clavicle fractures in the newborn.

A retrospective review of 21,632 live births from January 1982 to July 1987 was performed to determine the incidence and risk factors associated with fractures of the clavicle in the newborn. Fifty-eight fractures (57 patients) were identified, for an incidence of 2.7 clavicle fractures per 1000 live births. Fractures of the clavicle were associated with heavy neonates and shoulder dystocia. Three patients had concurrent clavicular fractures and Erb's palsy. These findings suggest that the incidence of clavicle fractures in the newborn may be reduced by identifying the macrosomic fetus and by minimizing shoulder dystocia. When clavicle fractures occur, a brachial plexus injury should be ruled out.

Apgar Score↗

PubMed1990

Joint replacement for ankylosed hips.

Forty-one fused hips in thirty-eight patients were converted to total hip replacement. The average length of follow-up was seven years. The predominant indications for conversion were progressively disabling pain in the low back or the hip, or both; loss of function due to immobility or malposition of the hip; and progressive pain and instability of the knee (usually ipsilateral). The postoperative arc of flexion averaged 87 degrees. Limb-length discrepancies improved an average of 2.5 centimeters. Postoperative function of the abductor muscles depended on the preoperative quality of those muscles and on the accuracy of the biomechanical restoration. Postoperative strength of the muscles of the hip improved for two years or more in most patients. There was complete or major relief of pain, improved mobility of the hip, and decreased dependence on supports for walking. There were nine failures: four because of sepsis, four because of loosening of the femoral component, and one because of malposition of the acetabular component. The failures were predominantly in patients who were fifty years old or less at the time of arthroplasty, patients who had had two or more previous operations, and patients who had had an injury to the hip. The quality of the results approached that after primary hip arthroplasty in older patients who have not had multiple previous operations on the hip. Survivorship analysis of the spontaneously fused hips that were treated with conventional hip replacement predicted a probability of survival of the implant of 96 per cent at thirteen years postoperatively (p = 0.048).

Adult↗

PubMed1990

Strength of initial mechanical fixation of screw ring acetabular components.

This study was conducted to determine the effects of design on the initial fixation of several types of screw-ring acetabular components. The components were tested in polyurethane foam to assess relative screw fixation strengths with a consistent material. Embalmed pelves from anatomic specimens were used to conduct paired tests between designs that showed large differences in insertional torque to failure in foam. The quality of the initial fixation in foam was found to be dependent on the design features of the components. Components with widely spaced, deep threads, and minimal thread interruptions offered the strongest initial fixation in foam. Tests in bone revealed a wide range of fixation strengths reflecting the variability in bone quality. No differences in fixation strength attributable to component design were observed in bone. When the insertional failure torque was greater than 60 N.m, one-half of the pelves fractured, and these fractures occurred with all designs. At failure torques less than 60 N.m, failure was predominantly due to thread strippage of the screw, with only two of 20 specimens experiencing pelvic fracture.

Acetabulum↗

PubMed1990

Treatment of osteoarthrosis secondary to congenital dislocation of the hip. Primary cemented surface replacement compared with conventional total hip replacement.

Seventy-four cemented conventional total hip arthroplasties (in fifty-five patients) and thirty-seven cemented surface replacements (in thirty-two patients) were done between 1971 and 1984 for treatment of osteoarthrosis secondary to congenital dislocation of the hip. The patients in the first group were older and had more severe dysplasia. In all patients, we tried to position the acetabular component at the level of the true acetabulum. In both groups, the operation relieved pain and improved the function of the hip in the short term. There were fewer and less severe early postoperative complications in the surface-replacement group, but the rate of long-term failure (revision or resection) was substantially higher. Survivorship analysis demonstrated that neither type of operation yielded durable results in younger patients; all revisions were in patients who were less than sixty years old. However, in older patients who had cemented conventional total hip arthroplasty, survivorship was excellent, regardless of the amount of dysplasia.

Adult↗

PubMed1989

The effects of dexamethasone on periarticular swelling and joint stiffness following fracture in a rabbit hindlimb model.

An established rabbit hindlimb model was used to determine the effects of systemic steroid administration on posttraumatic limb swelling and joint stiffness. Dexamethasone acetate was administered intramuscularly to the test rabbits in one of four doses two hours following fracture as well as one and two weeks later. Dexamethasone did not produce a significant decrease in swelling but did produce a statistically significant dose-dependent decrease in ankle stiffness compared to controls. Tibia torsional strength to failure was not adversely affected.

Animals↗

PubMed1989

Resection arthroplasty of the hip.

The results of forty-eight resection arthroplasties (Girdlestone procedures) in forty-three patients were analyzed. The indications were sepsis after a total hip replacement (thirty-three procedures), aseptic loosening of a total hip replacement (ten procedures), and primary septic arthritis (five procedures). The resection arthroplasty effectively eradicated the sepsis in all but three patients, who had a recurrence. Pain was alleviated in nearly all of the patients, but the ability to walk and the level of activity improved only slightly. Shortening of the limb ranged from three to eleven centimeters, and all patients used a support for walking. The six patients who had a bilateral procedure were able to walk using double supports. With regard to relief of pain, walking, and function, the results were significantly poorer in the women, particularly the older ones. The results were also significantly inferior in the patients who had had sepsis after a total hip replacement. Generally, walking, function, and the level of activity were better when much of the proximal end of the femur had been retained. Resection arthroplasty should spare as much of the proximal end of the femur as possible if a future replacement of the hip is contemplated.

Adult↗

PubMed1989

Instrumented measurements of laxity in patients who have a Gore-Tex anterior cruciate-ligament substitute.

Twenty patients who had substitution of the anterior cruciate ligament with a Gore-Tex synthetic ligament were evaluated preoperatively and postoperatively with the University of California at Los Angeles instrumented clinical-testing apparatus, which records anterior-posterior force versus displacement-response curves of the tibia with respect to the femur at 20 degrees of flexion of the knee. The mean age of the patients was thirty-three years (range, nineteen to fifty-four years). The duration of follow-up ranged from twenty-four to forty-four months (mean, thirty-one months). The mean preoperative difference in anterior laxity between the injured knee and the normal knee (4.5 millimeters with neutral rotation of the foot) was unchanged two years after the operation; at that time, all patients had an anterior laxity of the injured knee of more than eight millimeters, and 90 per cent had a difference in anterior laxity of more than two millimeters between sides. The mean values for anterior stiffness at fifty and 100 newtons of anterior force were unchanged after the operation, remaining at 40 to 50 per cent of normal levels. At 200 newtons, or 20.4 kilograms (forty-five pounds) of anterior force, the mean stiffness of the involved knee was 11 to 17 per cent greater than that of the normal knee. Clinically, there were improvements in both subjective and objective knee-rating scores. All but four patients had a reduction of at least one grade in the pivot-shift score; in thirteen, the pivot-shift sign was eliminated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

The effects of two nonsteroidal antiinflammatory drugs on limb swelling, joint stiffness, and bone torsional strength following fracture in a rabbit model.

Using a rabbit distal tibia fracture model treated by immobilization for three weeks, the effects of two nonsteroidal antiinflammatory drugs on postfracture limb swelling, joint stiffness, and torsional bone strength were examined. Limb swelling in rabbits treated with low-dose piroxicam was reduced by 39%, and high-dose piroxicam reduced limb swelling by 86%. Flunixin, tested at one dose, reduced swelling by 53%. Neither piroxicam nor flunixin affected ankle stiffness or tibia torsional strength.

Animals↗

PubMed1988

Efficacy of soft splints in reducing severe knee-flexion contractures.

This study evaluated the effectiveness of soft splints made from polyurethane foam in reducing severe knee-flexion contractures of patients with cerebral palsy. The splints were applied nightly over a period of 10 months. Knee-flexion contractures were reduced by an average of 24 degrees in all patients. Younger patients generally presented with less severe initial contractures and had the greatest percentage of improvement. When used on a single limb when bilateral contractures were present, sympathetic reduction of the contracture occurred to varying degrees in the unsplinted limb. It is recommended that the splints be replaced regularly to maximize their effectiveness. The benefit-to-cost ratio is extremely high and their low cost makes soft splints feasible for use in developing countries and by low-income families.

Adolescent↗

PubMed1988

The effects of dimethyl sulfoxide on posttraumatic limb swelling and joint stiffness. A review and an experimental study in rabbits.

Dimethyl sulfoxide (DMSO) is an inorganic compound with many interesting in vitro properties, including the ability to scavenge oxygen-free radicals. DMSO has been used to treat a variety of clinical conditions, especially musculoskeletal trauma, but valid data regarding its effectiveness are lacking. This paper reviews the pharmacology of DMSO and reports on its effectiveness in reducing posttraumatic limb swelling and ankle joint stiffness in a rabbit hind limb model. The left and right hind limbs of the test and control animals were instrumented and fractured identically. DMSO was applied daily to the skin of only one limb in the test animals. DMSO reduced postinjury ankle stiffness in both ankles of the test rabbits by 41% but had no effect on limb swelling compared to control rabbits. Postulated mechanisms of decreased joint stiffness include oxygen-free radical scavenging and inhibition of fibroblast proliferation.

Animals↗

PubMed1988

Tibial torque generation in a flexed weight-bearing stance.

Internal and external torque generated about the long axis of the lower extremity was measured in 18 male subjects who were instructed to twist with maximal effort against a fixed footplate containing an instrumented torque cell. Mean torque values ranged from 30 to 71 newton meters (Nm) depending upon the test conditions. Torques recorded during the flexed single-leg stance were 19% to 49% higher than those measured while seated. Values at 45 degrees of knee flexion were 11% to 16% greater than those at 20 degrees. Torques generated while wearing a ski boot were 8% to 11% greater than those recorded in an athletic shoe. When movement of the pelvis and upper torso was allowed, torque values were 17% to 49% higher than those recorded when the hips and shoulders were restrained which allowed only lower leg musculature to act in an isolated fashion. There were no differences between internal versus external generated torques when the hips and torso were restrained. When the hips and shoulders were unrestrained, internal torque was 12% greater than external torque. There were no strong correlations between generated torque and body weight or height. These generated torque values suggest that if ski bindings are set to American Society for Testing and Materials (ASTM) standards for twist-release torque, then upper torso and pelvic movement in conjunction with tensed knee musculature (i.e., a "locked knee") may be necessary to accomplish binding release. Use of the lower leg musculature alone (i.e., ankle twist) may not generate sufficient torque for release.

Adult↗

PubMed1988

Survival analysis of T-28 hip arthroplasty with clinical implications.

Seventeen years after its introduction, the T-28 and its successor (the TR-28) have proved to be a successful arthroplasty system, with very low long-term socket and femoral loosening rates, especially in older patients. The 10-year revision rate for aseptic loosening of the socket is only 2 per cent. This form of conventional cemented total hip replacement has provided pain relief and improved function in many individuals who have exhausted nonoperative treatment alternatives. Although there are still unsolved long-term problems for the young active patients, cemented hip arthroplasty continues to play an important role in joint replacement, and remains the treatment of choice in older and relatively inactive patients.

Activities of Daily Living↗

PubMed1988

The Dana total shoulder arthroplasty.

Fifty-six Dana unconstrained total shoulder arthroplasties in forty-seven patients were followed for a minimum of two years. The preoperative diagnoses included osteoarthritis, rheumatoid arthritis, traumatic arthritis, avascular necrosis, failed hemiarthroplasty, and failed total shoulder arthroplasty of another design. For all of the patients, the average rating for pain improved from 3 points preoperatively to 8 points postoperatively, and the average rating for function improved from 3 to 7 points. The ranges of abduction and of external rotation improved substantially in the shoulders that were affected by osteoarthritis, rheumatoid arthritis, or osteonecrosis. Ten patients were treated with a hooded glenoid component, designed to improve stability in shoulders in which the rotator cuff is deficient. In these shoulders, both the rating for pain and the rating for function improved, although the range of motion did not. Complications that required revision of the arthroplasty developed in five shoulders in which a regular component had been implanted and in two that had a hooded glenoid component. A radiolucent line developed at the bone-cement interface of the glenoid component in fifty-three shoulders, but only two revisions were done for loosening of the glenoid component.

Adult↗

PubMed1987

How do physicians adapt when the coronary care unit is full? A prospective multicenter study.

Reducing the numbers of coronary care unit (CCU) beds would decrease expensive unnecessary admissions, but might also block appropriate admissions. To study how physicians adapt to limited CCU beds, we compared their decisions to admit patients to the CCU when the CCU was full with those made when the CCU was not full. We studied 4479 patients who presented with symptoms suggesting acute cardiac ischemia to six New England hospital emergency rooms over 16 months. Of the 2931 patients found on follow-up not to have acute ischemia, 33% of those presenting when the CCU was not full were admitted to the CCU vs 24% of such patients presenting when the CCU was full (P = .0005), a 27% drop. Of the 725 patients proving to have angina pectoris, 74% of those presenting when the CCU was not full were admitted to the CCU vs 62% of such patients presenting when the CCU was full (P = .007), a 16% reduction. Of the 823 patients found to have myocardial infarction, 90% were admitted to the CCU both when the CCU was not full and when it was full. Importantly, for no group did mortality increase when the CCU was full. These data suggest that physicians can safely adapt to substantial reductions in the availability of CCU beds.

Adult↗

PubMed1987

Effective sample sizes for confidence intervals for survival probabilities.

We examine various methods to estimate the effective sample size for construction of confidence intervals for survival probabilities. We compare the effective sample sizes of Cutler and Ederer and Peto et al., as well as a modified Cutler-Ederer effective sample size. We investigate the use of these effective sample sizes in the common situation of many censored observations that intervene between the time point of interest and the last death before this time. We note that there is no a priori reason to treat upper and lower confidence intervals in a symmetric fashion since censored survival data are by nature asymmetric. We recommend the use of the Cutler-Ederer effective sample size in construction of upper confidence intervals and the Peto effective sample size in construction of lower confidence intervals. Two examples with real data demonstrate the differences between confidence intervals formed with different effective sample sizes. This study also illustrates the need for caution in the application of simulation studies to real problems.

Bacterial Infections↗