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R N Stauffer

Publications and source records attributed to R N Stauffer.

At least 19 recordsLinked to original sources
PubMed1992

Roentgenographic and mechanical performance of centrifuged cement in a simulated total hip arthroplasty model.

Roentgenographic analysis showed that centrifugation significantly reduced the gross and regional porosity of the cement compared with hand-mixed controls in a simulated total hip arthroplasty model. Static failure test of the prosthetic system demonstrated that the centrifuged cement had significantly greater strength than the hand-mixed cement. Under low-cycle fatigue tests of the same composite models, there was a trend for the centrifuged cement to be stronger than the hand-mixed specimens, although statistically it was not significant. Thus, centrifugation can reduce porosity and significantly improve the static strength of cement in a simulated in vitro total hip replacement model. When cement is used, any possible improvement in the physical properties of bone cement should be considered.

Analysis of Variance↗
PubMed1990

The effect of centrifugation on the mechanical properties of cement. An in vitro total hip-arthroplasty model.

An in vitro total hip-arthroplasty model was evaluated to determine if centrifugation of bone cement results in greater static strength and low-cycle fatigue strength than hand-mixing. The static-failure test of the stem, cement, and simulated bone composite demonstrated that the centrifuged cement had significantly greater static strength than the hand-mixed cement. However, under low-cycle fatigue tests on the same composite models, the centrifuged and hand-mixed specimens were not significantly different.

Biomechanical Phenomena↗
PubMed1989

Charnley total hip arthroplasty with cement. Fifteen-year results.

The results of the first 333 Charnley total hip arthroplasties that were performed with cement at the Mayo Clinic were reviewed a minimum of fifteen years postoperatively. Data were available for 166 of 170 hips of patients who were still alive. One hundred and thirty patients died, and thirty-seven hips were revised. At the time of this study, 80 per cent of the living patients had no pain, and 152 of the 160 hips remained much better than before the operation. Kaplan-Meier analysis of probable loosening of one or both components, on the basis of roentgenographic evidence, demonstrated a probability of loosening of 3 per cent incidence at one year after operation, 13 per cent at five years, 19 per cent at ten years, and 32 per cent at fifteen years. The probability of failure (that is, revision or symptomatic loosening) was 0.9 per cent at one year, 4.1 per cent at five years, 8.9 per cent at ten years, and 12.7 per cent at fifteen years. We did not identify a dramatic increase in the incidence of loosening or failure at any of the follow-up periods (one, five, ten, or fifteen years). With the Mayo Clinic clinical and roentgenographic system for scoring the hips, we found that ninety-seven hips had a good or excellent result; fifteen, a fair result; and thirteen, a poor result. (The scoring could not be completed for forty-one hips). The functional results deteriorated slightly over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗
PubMed1988

Vertebral fractures without neurological deficit. A long-term follow-up study.

Twenty-five patients, who did not have osteoporosis and who were between the ages of seventeen and sixty years, were treated for one or more stable compression fractures of a vertebra with compaction of less than 50 per cent and without an associated neurological deficit. The patients were followed for a minimum of nine years. Associated vertebral fractures (12 per cent) were identified during the first three months after the injury, but no deformity progressed after three months. Radiographic changes of degenerative disc disease were evident in eight patients, but the changes did not correlate with symptoms or with level of activity. With one exception, all patients functioned as well as uninjured subjects of comparable age. Patients who have a compression fracture of a vertebra should have serial radiographs made for at least three months to ensure that all fractured vertebrae are identified and to document any progression of deformity.

Adolescent↗
PubMed1988

Cemented total hip arthroplasty with contemporary techniques. A five-year minimum follow-up study.

A retrospective clinical and roentgenographic review was performed on 251 consecutive cemented total hip arthroplasties (THA) performed from 1978 to 1980 that had been followed a minimum of five years (range, five to seven years). All arthroplasties involved the use of a Harris Design II femoral stem, an intramedullary plug, a cement gun, and pulsatile lavage of both the acetabulum and the femoral canal. At the final follow-up examination, 98% of the patients had excellent results. The average Harris hip score was 47 points preoperative and 97 points postoperative. There were three definitely loose femoral stems, one probably loose, and two possibly loose. There was one loose acetabular component, no revisions or operations were performed. When comparing this series with a similar study, there were statistically improved results in all parameters. Results from this study of cemented THAs using contemporary techniques and prosthetic stem design represent the standard for comparison when evaluating alternative THA systems.

Adult↗
PubMed1987

Fixed-head and bipolar hip endoprostheses. A retrospective clinical and roentgenographic study.

A retrospective review of 1,001 hip hemiarthroplasties was performed. The prosthetic designs were grouped into fixed-head types (682 cases) and bipolar types (319 cases) for comparison. The main indications for operation were femoral neck fracture and avascular necrosis of the femoral head. Clinical and roentgenographic data for different follow-up periods were compared between prosthetic types, using multivariate analysis. Roentgenographic loosening of the femoral component was noted in 25.4% of cases but was significantly higher (P less than .05) in the bipolar groups for a follow-up period less than 2 years, regardless of the method of fixation. The acetabular erosion rate was significantly higher (P less than .05) in the fixed head group, but this finding was related to length of follow-up period, bone porosity, and prosthesis/acetabulum fit. The reoperation rate, including revision to total hip arthroplasty, was higher in the fixed-head group (12.5%) than the bipolar group (7.2%). Based on Kaplan-Meier survivorship analysis, 13.7% of the bipolar and 22.9% of the fixed-head hip endoprostheses are expected to be reoperated 8 years after initial implantation. Cement fixation of the femoral component led to a higher prosthesis survival rate, regardless of type. Both prosthetic types are useful in hip surgery, but the bipolar type appears to be indicated in younger and more active patients, whereas the fixed-head design is more suitable for older patients with femoral neck fractures.

Acetabulum↗
PubMed1987

Kinematic rotating-hinge total knee arthroplasty.

The first fifty kinematic rotating-hinge total knee arthroplasties that were done at the Mayo Clinic were reviewed. The indication for use of this prosthesis was either ligamentous instability or loss of bone, or both. At a mean length of follow-up of fifty months (range, twenty-nine to seventy-nine months), the clinical results of thirty-eight knees in thirty-six patients were evaluated. Fifteen of the thirty-eight knees had had a primary arthroplasty and twenty-three had had a revision arthroplasty using the kinematic rotating-hinge prosthesis. Using the knee-rating score of The Hospital for Special Surgery, there were fourteen excellent, twelve good, five fair, and five poor results. For two knees there was inadequate information to calculate a knee-rating score. Lucent lines that were more than one millimeter in width were seen with 25 per cent of the femoral and 50 per cent of the tibial components. Progression of lucent lines was observed in thirteen knees, and five knees showed probable radiographic loosening. The high incidence of complications was distressing, with a 16 per cent rate of sepsis, a 22 per cent rate of patellar instability, and a 6 per cent rate of breakage of the implant. In our opinion, this implant should be used only in knees in which there is functional absence of a collateral ligament that cannot be managed by soft-tissue reconstruction.

Adult↗
PubMed1979

Total joint arthroplasty. The ankle.

When conservative measures fail to relieve significant disability due to ankle joint disease, the only surgical method of treatment has been arthrodesis. Because of less than ideal results and other long-term problems with ankle arthrodesis, and after numerous investigation to characterize the ankle mechanically, we developed a prosthetic ankle joint replacement. The Mayo total ankle replacement is a metal-on-polyethylene, congruent, constrained prosthesis. Analysis of 94 patients (102 ankle prostheses) revealed good clinical results in patients with rheumatoid arthritis and in older persons with posttraumatic degenerative disease. Younger, more active patients in the latter category had more disappointing results. Further design development is under way to improve range-of-motion characteristics, decrease constraint forces, and improve bone fixation of the prosthetic components.

Ankle Joint↗
PubMed1979

Total joint arthroplasty. The role of biomechanics.

The role of biomechanics is intricately involved in total joint replacement from its inception to its clinical use. By integrating knowledge of joint function and material properties, the artificial joint is designed and tested. After clinical use, the joint function is again studied and failure modes are defined. Biomechanics is the single most important discipline that can be employed to study the cause of failure in order to improve design and technique. This will increase the reliability of, and decrease the incidence of failure associated with, total joint replacement.

Arthroplasty↗
PubMed1979

Limb fractures in a defined population. I. Frequency and distribution.

This population-based study revealed that 2,519 limb fractures occurring during a 3-year period produced an age-adjusted incidence rate for all limb fractures of 1,596 per 100,000 person-years. Fractures of the upper limb had a bimodal age distribution and were commoner than those of the lower limb, which had a J-shaped age distribution. The most frequent anatomic site was the lower end of the radius and ulna. Limb fractures occurred as solitary events in 93% of cases; only 4% were classified as open and more than half of the total were closed and undisplaced. Fractures were distributed evenly throughout all time periods of the day. The commonest place of fracture occurrence was the home, and the most important direct cause was falls, particularly in females. A wide range of sports activities were a major source of fractures, particularly in younger males. Underlying bone pathology was uncommon, other contributory causes being more important, particularly in the elderly. The increased ratio of metaphyseal to diaphyseal fractures with age indicated a relative loss of cancellous bone in the elderly, but no evidence was found to suggest that elderly women had reduced resistance of bone to impact forces in comparison with elderly men.

Accidents, Home↗
PubMed1979

Limb fractures in a defined population. II. Orthopedic treatment and utilization of health care.

This study describes the orthopedic treatment and utilization of health care obtained by 2,333 patients in the population of Rochester, Minnesota, who suffered 2,519 limb fractures during the period 1969 through 1971. Overall, 24% of fracture occurrences required patient hospitalization, the remainder involving care on an ambulatory basis only. The mean number of physician visits was 4.5 per fracture, with the visits occurring during an interval of 103 days from the time of first evaluation. Fifteen percent of limb fractures were subject to at least one surgical operative procedure as part of their orthopedic treatment. The frequency of operative treatment increased markedly with patient age. Seventeen percent of patients with limb fractures received physiotherapy or occupational therapy or both, 4% were ambulatory patients, and the remainder were hospital inpatients. Fractures of the head and neck of the femur constituted only about 7% of fractures in the series, yet utilized an inordinate proportion of health care resources. Hip fractures were responsible for 27% of the hospital admissions, 52% of all bed days utilized, and 56% of the physiotherapy sessions.

Adolescent↗
PubMed1977

Severe degenerative joint disease. Mild and moderately severe hemophilia A.

Severe degenerative joint disease developed in three adults with mild to moderately severe hemophilia A, as judged by the clinical course and by levels of factor VIII coagulant. Bilateral total hip arthroplasty was required in one patient, unilateral hip arthroplasty in the second, and a recommendation for bilateral knee replacement in the third. The pathogenesis of the arthropathy may be multifactorial and the result of repeated joint hemorrhage that remains unrecognized and inadequately treated. These observations suggest the need for more careful monitoring of patients who have relatively mild hemophilia.

Adult↗
PubMed1977

Quo vadis.

Explore the source record for details and available documents.

Arthroplasty↗
PubMed1977

Total ankle joint replacement.

The ankle is an inherently stable, kinematically simple joint that bears tremendous compression forces with relative ease because of a large load-bearing surface area. Disabling disease of the ankle is less common than at the hip or knee joints, but is not rare. Ankle arthrodesis seems less than ideal as a technique of surgical treatment. Total ankle joint replacement seems to be a clinically possible alternative on the basis of experience with 76 procedures performed during a 31-month period. Continuing clinical experience is resulting in more gratifying results by the avoidance of technical errors and better selection of patients.

Adult↗
PubMed1977

Muscle force analysis of the lumbar spine.

A mathematical analysis of the complex musculature controlling the lumbar spine was performed, using computer analysis of muscle areas seen on serial cross sections through two fresh human cadaver trunks. Physiologic cross sectional areas were used to approximate maximal potential forces generated, and three dimensional centroid lines of muscles were used to approximate their direction of action. Results indicate that the total extensor moment exceeds the total flexor moment only slightly; the rectus abdominis, internal oblique, and external oblique muscles contribute approximately one third to total flexor moment; the erector spinae group of muscles contributes approximately one half of the total extensor moment; and in rotation (twisting) the large abdominal oblique muscles dominate over small "rotator" muscles of the spine. The maximal calculated total extensor moment was 2860 kg.-cm. The magnitude of flexor and extensor moments suggests that the rise in intra-abdominal pressure during lifting is produced by the transverse and posterior oblique abdominal muscles, and not by the rectus abdominis.

Biomechanical Phenomena↗
PubMed1977

Force and motion analysis of the normal, diseased, and prosthetic ankle joint.

A 2-dimensional motion and force study of the ankle joint during gait has been carried out on normal subjects and patients with ankle joint disease, before and 1 year following total ankle replacemetn. The methods employed involved the use of high-speed motion picture film, force plate and foot-switch data. The Achilles and anterior tibial tendon forces, the compressive and tangential (shear) forces across the ankle during stance phase of gait were determined, based on a quasi-static analysis. During stance phase of gait normal subjects used a mean of 24.4 degree of sagittal plane ankle motion. Patients with ankle joint disease showed reduced motion which returned to near normal values 1 year following total ankle replacement. Compressive force across the ankle joint rose to about 5 times body weight during the latter part of stance phase. Backward, or aft, shear forces or nearly full body weight were demonstrated during all but the last 20% of stance phase. Patients with ankle joint disease apparently altered their gait to markedly reduce these forces. Following total ankle replacement, shear forces returned toward more normal values, but compressive forces were not significantly changed.

Adult↗
PubMed1976

Total hip arthroplasty in Paget's disease of the hip.

For thirty-two patients with Paget's disease of the pelvis, mechanical disruption of the hip joint caused sufficient pain and disability to require total hip-replacement arthroplasty. Three of the patients had had fractures of the femoral neck. No unusual complications were encountered and the results were excellent.

Aged↗