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Biomedical subjects

M D Ries

Publications and source records attributed to M D Ries.

At least 37 records · Page 2Linked to original sources
PubMed1997

Distribution of orthopaedic surgeons, lawyers, and malpractice claims in New York.

The New York State Department of Health Medical Malpractice Insurance Database was used to determine the number and location of malpractice claims filed by residents of New York State against board certified orthopaedic surgeons between 1979 and 1993. The numbers of board certified orthopaedic surgeons, lawyers, law firms doing medical malpractice work, and malpractice claims per capita for each county were calculated. Stepwise linear regression analysis was used to determine whether the per capita rate of malpractice claims was predicted by the population density of board certified orthopaedic surgeons, law firms filing malpractice claims, or total population of lawyers. Three thousand one hundred eighty-two malpractice claims were filed during the period of interest. The per capita rate of malpractice claims did not correlate with the population density of board certified orthopaedic surgeons. The per capita malpractice claim rate, however, was significantly correlated with the population density of law firms filing malpractice claims and with the overall population density of lawyers. Orthopaedic practices located in areas with high concentrations of lawyers involved in medical malpractice litigation appear to have a higher risk of having malpractice claims filed against them than practices located in other areas.

Humans↗
PubMed1997

Acetabular strains produced by oversized press fit cups.

The purpose of this study was to determine the amount of acetabular deformation that occurs when acetabular components of different sizes are press fit. The change in acetabular volume was calculated for 1- to 3-mm oversized cup diameters with acetabuli ranging from 40 to 80 mm. An axisymmetric finite element model was used to determine the maximum acetabular strain that occurs when oversized cups are inserted in different acetabuli. The highest acetabular strains occur at the cup periphery, indicating that the resultant compressive force between the lateral pelvis and cup enhances press fit stability. In addition, higher maximum strains occur when the same millimeter amount of oversizing is used in a small compared with a large acetabulum. When a constant millimeter increment in cup oversizing is used, there may be a greater risk of pelvic fracture in a small acetabulum and a greater risk of inadequate press fit stability in a large acetabulum. To achieve the same amount of acetabular deformation and magnitude of strain, more oversizing is needed in a large acetabulum and less oversizing is needed in a small acetabulum. These results suggest that 1 mm of oversizing should be used for cups that are less than 52 mm in diameter, 2 mm of oversizing should be used for cups from 52 to 76 mm in diameter, and 3 mm of oversizing should be used for cups that are more than 76 mm in diameter.

Acetabulum↗
PubMed1996

Intraoperative modular stem lengthening to treat periprosthetic femur fracture.

Fracture of the femur around a femoral prosthesis can be a difficult problem to manage. Treatment options consist of traction, allograft struts, or plating with cerclage fixation, and revision arthroplasty. Intramedullary stabilization is usually preferable to plating for treatment of diaphyseal femur fractures; however, for a fracture around a cementless stem, disruption of the biologically fixed proximal area of the implant and revision to a long-stem component are generally required to permit intramedullary fixation of the fracture. Many modular femoral stems are currently available. Some of these have both proximal and distal modular options. Distal modularity provides the surgeon treating a fracture around a femoral component with a unique opportunity to lengthen the stem during surgery by adding an attachment to the distal stem through the fracture site.

Adult↗
PubMed1996

Extended tibial tubercle osteotomy in total knee arthroplasty.

Thirty tibial tubercle osteotomies were performed to obtain exposure and facilitate patellar tracking in 29 patients who underwent total knee arthroplasty. The thickness and width of the bone fragment were gradually tapered from proximal to distal. Fixation was obtained with three or four titanium screws. Average follow-up period was 18 months. Twenty-nine of the osteotomies healed primarily. In one patient, postoperative displacement of the tibial tubercle developed requiring additional screw and suture fixation. Extended tibial tubercle osteotomy is a useful technique during difficult total knee arthroplasty. Poor tibial bone stock is a relative contraindication. The authors recommend that a long tapered bone fragment that is 1.5 to 2 cm thick at the level of the tibial tubercle be elevated and fixation achieved with screws.

Adult↗
PubMed1996

Safety and efficacy of ethylene oxide sterilized polyethylene in total knee arthroplasty.

Eleven unassembled metal backed patellar interfaces were inoculated with 0.1 ml of Sportol (Bacillus subtilis variety niger spore) and then assembled. Ten of the 11 implants were exposed to 1/2 of a standard ethylene oxide sterilization cycle. The remaining implant was left unsterilized as a control. All the implants were separately incubated in soybean casein digest broth for 7 days at 30 degrees to 35 degrees C and tested for positive growth of Bacillus subtilis. To measure residual ethylene oxide content, 4 ultrahigh molecular weight polyethylene tibial inserts were exposed to a full ethylene oxide sterilization cycle. The implants were removed from the sterilization chamber and tested for residual ethylene oxide at 3, 5, 8, and 9 days after sterilization using an exhaustive extraction headspace technique. Residual ethylene oxide was measured in 3 additional implants 26 days after sterilization. No growth of Bacillus subtilis occurred on any of the 10 inoculated and ethylene oxide sterilized metal backed patellar components, whereas positive growth occurred on the inoculated, unsterilized control implant. Residual ethylene oxide measured in the tibial inserts at 3, 5, 8, and 9 days after sterilization was 23, 15, 12, and 9 ppm, respectively. Twenty-six days after sterilization, residual ethylene oxide was below the minimum detectable level of the measurement technique (5 ppm).

Bacillus subtilis↗
PubMed1996

Improvement in cardiovascular fitness after total knee arthroplasty.

Patients who have osteoarthrosis involving weight-bearing joints typically have a gradual decline in physical activity, which is often associated with cardiovascular deconditioning. After joint replacement, many patients resume routine walking and recreational activities, which may improve aerobic capacity. The purpose of the present study was to determine the effect of total knee arthroplasty on cardiovascular fitness. Nineteen patients who had had total knee arthroplasty (the arthroplasty group) performed an exercise test for cardiovascular fitness preoperatively. Sixteen of these patients were tested again at one year postoperatively and thirteen, at two years postoperatively. Sixteen patients in whom osteoarthrosis of the knee was being treated medically (the control group) were tested at the time of enrollment in the study and one year later. Nine of these patients also were tested two years after enrollment. All of the patients completed the Arthritis Impact-Measurement Scales (AIMS) at each examination. Fitness was assessed by the performance of a progressive maximum exercise test with use of a bicycle ergometer and a metabolic cart. All patients achieved the anaerobic threshold. One year postoperatively, the patients in the arthroplasty group demonstrated an increase, which approached significance, in maximum oxygen consumption (measured in milliliters of oxygen per minute) (p = 0.07), maximum oxygen consumption corrected for body weight (p = 0.08), and percentage of predicted maximum uptake of oxygen (p = 0.06). Two years after the total knee arthroplasty, the patients had a significant improvement with regard to all three parameters (p = 0.008, 0.005, and 0.005, respectively). The patients in the control group demonstrated a significant decrease in duration of exercise and in maximum workload at one year (p = 0.003 and 0.005, respectively) and at two years (p = 0.008 for both parameters). Physical activity had increased in the arthroplasty group but not in the control group, as demonstrated by the results of the Arthritis Impact-Measurement Scales. These findings demonstrate a trend toward improvement in cardiovascular fitness one year after total knee arthroplasty and a significant improvement two years postoperatively for patients who had been able to resume routine functional activities because of the arthroplasty. These improvements compared favorably with the static pattern or the decline in the measures of fitness that were observed in the control group. Our results should be considered preliminary because of the relatively small number of patients who were studied.

Aged↗
PubMed1996

Impacted cancellous autograft for contained bone defects in total knee arthroplasty.

Techniques of bone grafting for peripheral tibial defects in total knee arthroplasty are well described using solid bone graft or metal wedges. Central contained defects may be irregularly shaped and not easily managed with bulk grafts or wedges. Morselized grafts loosely packed into the defect may allow cement to intrude into the interstices between the graft fragments. However, impaction of the morselized autograft into a contained defect can permit complete filling of the area with graft and prevent undesirable cement intrusion. This article describes the successful use of this technique in eight patients who underwent primary total knee arthroplasty.

Aged↗
PubMed1996

Varus migration of PCA stems.

Forty-seven patients with cementless, porous-coated anatomic hip replacements were evaluated after a minimum 2-year follow up with specific attention to varus migration of the stem. A cadaver study was done to define a relationship between projected size of the lesser trochanter seen radiographically, rotation of the femur, and stem position. Seven (15%) of the stems migrated into varus with the distal tip moving laterally. Thigh pain occurred in patients with varus migration and those with no change in stem position. A lower percent canal fill was seen on the lateral radiograph (P < .001) and larger average width of radiodense lines in zone 1 superolateral, and zone 6, midstem medial (P < .005) in the patients with varus migration. Poor distal stability associated with a lower percent canal fill at the stem tip seen on the lateral radiograph may result in varus migration.

Biomechanical Phenomena↗
PubMed1996

Fatigue strength of polyethylene after sterilization by gamma irradiation or ethylene oxide.

The oxidation level of ultrahigh molecular weight polyethylene specimens sterilized by gamma irradiation in either air or Ar gas was compared with that of unsterilized and ethylene oxide sterilized ultrahigh molecular weight polyethylene. The fatigue strength of ultrahigh molecular weight polyethylene specimens sterilized by gamma irradiation in air was compared with that of unsterilized and ethylene oxide sterilized ultrahigh molecular weight polyethylene. At the specimen surface, oxidation was highest for ultrahigh molecular weight polyethylene gamma irradiated in air, lower for ultrahigh molecular weight polyethylene gamma irradiated in Ar gas, and absent in unsterilized and ethylene oxide sterilized ultrahigh molecular weight polyethylene. At a depth of 3.5 mm below the specimen surface, oxidation levels were equivalent for ultrahigh molecular weight polyethylene gamma irradiated in either air or Ar gas whereas unsterilized and ethylene oxide sterilized specimens were again unoxidized. Thus, even in an inert atmosphere, oxidative degradation of gamma irradiated ultrahigh molecular weight polyethylene occurs. The 10 million cycle fatigue strength was similar for unsterilized and ethylene oxide sterilized ultrahigh molecular weight polyethylene whereas the fatigue strength of gamma irradiated in air ultrahigh molecular weight polyethylene was lower. Results of this study show that ethylene oxide gas does not degrade ultrahigh molecular weight polyethylene whereas gamma radiation in air causes changes in the polymer that adversely affect its mechanical properties. Ethylene oxide gas is a viable alternative to gamma radiation in air that avoids oxidation and fatigue strength degradation known to accompany irradiation of ultrahigh molecular weight polyethylene polymer bearing surfaces in total joint implants.

Biophysical Phenomena↗
PubMed1996

Osteoarthritis as a determinant of an adverse coronary heart disease risk profile.

BACKGROUND: Osteoarthritis is associated with obesity, sedentary behavior and poor fitness. This study was conducted to test the hypothesis that risk factors for coronary heart disease (CHD) are more prevalent among patients with osteoarthritis than among non-arthritic adults of the same age and sex. METHODS: Forty-six patients with osteoarthritis of the hip and/or knee were evaluated; 23 non-arthritic subjects served as control group. A panel of metabolic risk factors were measured including body mass index (BMI), waist-hip ratio (WHR), blood pressure, fasting blood glucose, and serum lipids and apoproteins. RESULTS: Measures of arthritis severity confirmed marked disability and deformity in the arthritis group. Patients reported the performance of less aerobic exercise than controls. Compared with controls, patients were noted to have greater mean BMI (31.2 +/0- 5.9 versus 24.6 +/- 3.2 kg/m2, P < 0.000005), WHR (0.88 +/- 0.07 versus 0.83 +/- 0.08, P < 0.05), systolic blood pressure (140.8 +/- 17.9 versus 131.3 +/- 15.3 mmHg, P < 0.05) and fasting blood glucose (105.0 +/- 24.6 versus 93.2 +/- 7.0 mg/dl, P < 0.01), and lower mean high-density-lipoprotein cholesterol (47.9 +/- 10.9 versus 56.7 +/- 17.1 mg/dl, P < 0.05). Nonsignificant trends for higher mean diastolic blood pressure and serum triglycerides were also noted in the arthritic group. Mean estimated risk for development of CHD within 10 years of evaluation was greater in the arthritic than in the control group (21.6 +/- 14.4% versus 15.2 +/- 11.7%, P < 0.05). CONCLUSION: Patients with moderately severe to end-stage lower extremity osteoarthritis may be at advanced risk for the development of CHD by virtue of their unfavorable risk factor profile.

Aged↗
PubMed1995

Cardiovascular fitness and health in patients with end-stage osteoarthritis.

OBJECTIVE: To evaluate the cardiovascular fitness of a group of patients with severe osteoarthritis (OA). METHODS: Thirty-seven patients with end-stage OA were evaluated just before hip or knee replacement surgery. Severity of arthritis was evaluated using standardized techniques. Patients and age- and sex-matched controls underwent a single, maximal, symptom-limited, cardiopulmonary exercise test using arm or leg ergometry and a metabolic cart to measure expired respiratory gases. RESULTS: Severe musculoskeletal disability and deformity was confirmed in the OA patient group. During exercise testing, OA patients were able to perform physiologically maximal cardiopulmonary exercise. Arthritis patients were noted to be severely deconditioned, with reduced peak oxygen consumption (OA hips mean +/- SD 14.9 +/- 4.2 versus control hips 19.0 +/- 4.6, P < 0.0001; OA knees 12.8 +/- 3.7 versus control knees 17.6 +/- 5.2 ml/kg/minute, P < 0.0005). A trend for more frequent manifestations of coronary heart disease in OA patients than in controls (27% versus 13%; P > 0.05) was also noted. CONCLUSION: Patients with end-stage lower extremity OA are severely deconditioned. This may place them at incremental risk for the development of coronary heart disease.

Aged↗
PubMed1995

Femoral head autograft in simultaneous primary and revision total hip arthroplasty.

Bilateral total hip arthroplasty during one anesthetic procedure can be beneficial in properly selected patients. For patients who have a failed hip arthroplasty requiring revision and a contralateral arthritic hip requiring primary arthroplasty, bilateral surgery permits the resected femoral head from the primary procedure to be used as a fresh autogenous bone-graft during the revision procedure. Four patients underwent combined primary hip arthroplasty and contralateral revision hip arthroplasty during one anesthetic procedure. The femoral head obtained during the primary procedure was used as a structural acetabular bone-graft in three patients, and bone slurry was used to fill cavitary acetabular defects in one patient. A femoral neck autograft was used to reconstruct a calcar defect in one of the patients. After an average follow-up period of 27 months, all hips were functioning well with healed bone-grafts and stable prosthetic components.

Acetabulum↗
PubMed1995

Feasibility of maximal cardiopulmonary exercise testing in patients with end-stage arthritis of the hip and knee prior to total joint arthroplasty.

STUDY OBJECTIVE: Although no studies exist, to our knowledge, that examine the feasibility and safety of stress testing in a consecutive series of patients with severe arthritis, musculoskeletal conditions are often listed as relative contraindications to graded exercise testing. The current study was designed to examine the feasibility of maximal exercise testing in patients with end-stage arthritis prior to total joint arthroplasty. DESIGN: An observational and descriptive study in a consecutive series of patients with severe arthritis. SETTING: This study was conducted in the outpatient clinics and cardiopulmonary exercise physiology laboratory of a rural teaching hospital. PARTICIPANTS: Sixty-one patients with severe osteoarthritis and rheumatoid arthritis were recruited from the orthopedic surgical service immediately before total joint arthroplasty of the hip, knee, or both. A reference group of 23 nonarthritic control patients were recruited from the general medical population of the same hospital and subjected to measures of arthritis severity. MEASUREMENTS AND RESULTS: The severity of arthritis was graded by assessment of variables reflective of subjective symptoms, lifestyle impact, joint deformity, and radiographic abnormality. Arthritic subjects underwent a single graded, maximal, symptom-limited, cardiopulmonary exercise test using an electronically braked ergometer and a metabolic cart. Subjects were first asked to pedal with their legs; those apparently incapable performed the same task using their arms. Ninety-five percent of subjects who presented for an exercise test were capable of symptom-limited exercise. Of 29 patients evaluated before hip replacement, 66% completed leg tests, 31% completed arm tests, and 3% were incapable of symptom-limited exercise. Of 30 patients evaluated before knee replacement, 57% completed leg tests and 37% completed arm tests, while 7% were incapable of symptom-limited exercise. Two patients were evaluated before hip and knee surgery; one completed a leg study and one completed an arm study. Among the 37 subjects completing leg tests, a mean percentage of age-predicted maximum heart rate (APMHR) of 92 +/- 11% and a mean respiratory exchange ratio (RER) of 1.15 +/- 0.13 were noted. Among the 21 completing arm tests, a mean percentage of APMHR of 87 +/- 11% and a mean RER of 1.10 +/- 0.10 were observed. High rates of achievement of physiologic values indicative of maximal exercise (80% or more of APMHR and RER > or = 1.0) were noted in individuals in both exercise groups. Similar findings were noted regardless of the patient's subjective symptomatic limitation to exercise and the presence or absence of documented or suspected coronary heart disease. CONCLUSIONS: Most patients with severe arthritis are capable of maximal, symptom-limited exercise using ergometry methods. Ergometry stress testing may be a viable, low-cost alternative to dipyramidole-thallium testing or cardiac catheterization in some patients with arthritis warranting objective assessment of known or suspected cardiac disease.

Aged↗
PubMed1995

Relationship between severity of gonarthrosis and cardiovascular fitness.

Cardiovascular fitness was assessed in 3 groups of patients having varying severity of gonarthrosis. Group I consisted of 16 patients with severe knee symptoms scheduled for total knee arthroplasty. Group II included 17 patients with medically treated osteoarthrosis who were not considered surgical candidates because knee symptoms were not severe. Group III consisted of 14 healthy control patients with no lower extremity arthritis. All patients were evaluated with Hospital for Special Surgery knee scores, Arthritis Impact Measurement Scale questionnaires, and a cardiopulmonary exercise test using semi-upright bicycle ergometry. All patients achieved anaerobic threshold during exercise. Mean (+/- standard deviation) maximum oxygen consumption (VO2) at peak exercise was 13.9 +/- 3.3 for Group I, 16.2 +/- 4.1 for Group II, and 21.5 +/- 3.9 for Group III. Mean (+/- standard deviation) Hospital for Special Surgery score was 55 +/- 7 for Group I, 70 +/- 14 for Group II, and 100 +/- 1 for Group III. Lower Hospital for Special Surgery score was associated with lower VO2 at peak exercise, suggesting that inactivity secondary to more severe arthritic symptoms can result in cardiovascular deconditioning. The association between severity of gonarthrosis and cardiovascular deconditioning supports the concept that a regular exercise program should be recommended for patients with arthritis. Also, for patients who are surgical candidates, the practice of delaying total knee arthroplasty may be associated with worsening cardiovascular fitness, particularly when physical activity becomes more limited. The expected longevity of implant function as well as the effect of continued arthritic symptoms on cardiovascular fitness should be considered when determining the optimal time for a patient to undergo total knee arthroplasty.

Activities of Daily Living↗
PubMed1994

Osteolysis associated with cemented total knee arthroplasty. A case report.

Osteolysis induced by particulate debris occurs within 5 years after cementless total knee arthroplasty, but has not been reported to be a problem after cemented total knee arthroplasty. It has been suggested that the bone-cement interface may form a barrier to polyethylene-debris migration, thereby limiting bone loss. The authors have observed osteolysis in a 75-year-old woman 9 years after cemented total knee arthroplasty. An osteolytic area appeared to return to an area of normal bone architecture 3 years after the removal of synovium and particulate debris without implant revision.

Aged↗