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Biomedical subjects

C M Evarts

Publications and source records attributed to C M Evarts.

At least 19 recordsLinked to original sources
PubMed1992

A collarless cobalt-chrome femoral component in uncemented total hip arthroplasty. Five- to eight-year follow-up.

We implanted 57 uncemented cobalt-chrome porous-coated collarless femoral components into 51 patients (mean age 49 years). At review, five to eight years postoperatively, good or excellent results were recorded in 70% by the Mayo Clinic hip evaluation and in 84% by the Harris hip score. Revision for aseptic loosening of the femoral stem was necessary in only one hip. Thigh pain diminished with time and was present in only two hips at the time of review. Endosteal bone formation was seen at the junction of the smooth and the porous segments of the stem in 94% of hips and in 60% it continued after three years. In 90% of hips, proximal femoral atrophy did not progress after three years. Discontinuous radiolucent lines were seen around 30% of stems, most commonly in zones I, IV and VII. They were not progressive in 94% and their presence did not correlate with the clinical outcome.

Activities of Daily Living↗
PubMed1992

Prevention of heterotopic ossification with irradiation after total hip arthroplasty. Radiation therapy with a single dose of eight hundred centigray administered to a limited field.

Sixty-two hips in fifty-five patients who were considered to be at risk for postoperative heterotopic ossification were randomly divided into two groups: one received a single 800-centigray dose of limited-field radiation and the other, 1000 centigray of limited-field radiation in divided doses. The risk for heterotopic-bone formation was identified on the basis of previously described criteria, which included previous heterotopic ossification after an operation about the hip, hypertrophic osteoarthritis or post-traumatic osteoarthrosis characterized by formation of extensive osteophytes, radiographic evidence of diffuse idiopathic skeletal hyperostosis, ankylosing spondylitis, and male sex. The treatment portals excluded prosthetic surfaces that were intended for biological fixation by ingrowth of bone. At a minimum six-month follow-up, progression of heterotopic ossification had occurred in seven (21 per cent) of thirty-four hips in the first group and in six (21 per cent) of twenty-eight hips in the second group. The ossification had advanced more than one grade in only one hip. Extra-field ossification occurred in fifteen (43 per cent) of thirty-five hips that had not had previous heterotopic ossification. Since the time of the study, the treatment portal has been modified to include the lateral aspect of the greater trochanter, so that the risk of bursitis associated with ossification in this area is minimized. Single-dose limited-field radiation is effective for the prevention of heterotopic ossification, without compromise of early fixation of an uncemented implant.

Adult↗
PubMed1991

Prevention of heterotopic ossification in high-risk patients by radiation therapy.

Heterotopic ossification (HO) is a frequent occurrence after cemented and cementless total hip arthroplasty (THA). Patients at risk for this complication include those with preexisting ipsilateral or contralateral HO, diffuse idiopathic skeletal hyperostosis, hypertrophic osteoarthrosis, posttraumatic arthritis, and ankylosing spondylitis. Low-dose radiation therapy effectively prevents HO in this high-risk group when treatment is begun early in the postoperative period. A prospective evaluation has established the efficacy of fractionated and single-dose radiation therapy protocols. Limited radiation portals are used in patients receiving cementless prostheses. A rectangular radiation portal obliquely oriented to the prosthesis enables radiation treatment of the periarticular soft tissues while avoiding exposure of the bone-prosthesis interface. Radiation therapy to this interface may inhibit or delay bony ingrowth. Radiation therapy is the only treatment used to prevent HO that is delivered locally and not systemically. Low-dose radiation therapy using a limited radiation portal is the treatment of choice to prevent HO in high-risk patients after cementless THA.

Hip Prosthesis↗
PubMed1990

The use of postoperative irradiation for the prevention of heterotopic bone after total hip replacement with biologic fixation (porous coated) prosthesis: an animal model.

Radiation has been shown to be effective in the prevention of heterotopic bone. The exact etiology of heterotopic bone is unknown. Total Hip prosthetic devices that do not depend upon bone cement for fixation have become increasingly popular. The mechanism by which the bone forms around the prosthesis is similar to the process by which fractures heal which has been shown to be sensitive to irradiation. Using a rabbit model we have undertaken a study to investigate the effect of irradiation on the bony ingrowth on porous coated implants. Forty-five rabbits had porous coated implants surgically placed in the tibiae bilaterally. Each rabbit had one tibae randomly irradiated with 1,000 cGy in 5 fractions starting on the first post-operative day. Animals were sacrificed weekly starting 2 weeks post-operatively and the tibae were sent for pullout studies. The amount of force necessary to pullout the treated tibae was statistically less than the amount of force necessary to remove the untreated tibae at 2 weeks. From 3 weeks on there was no difference in the force necessary to remove the prosthesis from the untreated or treated tibae. Histologically, the untreated tibae showed bone formation while the treated tibae did not. Because of these results, it is suggested that the treatment of patients at risk for development of heterotopic bone be modified to only include the area between the femur and pelvis avoiding treatment of the prosthetic device.

Animals↗
PubMed1990

Randomized trial comparing single dose versus fractionated irradiation for prevention of heterotopic bone: a preliminary report.

Radiation therapy has been shown to prevent heterotopic bone formation in high risk patients undergoing total hip replacement. A number of doses have been used without a randomized trial comparing one dose regimen against another. A prospective randomized trial was undertaken comparing 10 Gy in 5 fractions versus 8 Gy in 1 fraction. Forty-seven patients have been randomized at the time of this evaluation with 37 patients eligible for analysis. The pre-operative, immediate post-operative and 2 month post-operative radiographs were graded. At the time of this analysis, 17 patients were randomized to the 8 Gy arm with 20 patients in the 10 Gy arm. Patients were treated with limited fields so as to only cover the area at risk for development of heterotopic bone to prevent adverse effects on biologic fixation of uncemented implants. When comparing the pre-operative, operative, and 2 month post-operative radiographs, only four patients (1 patient in the 8 Gy arm and 3 patients in the 10 Gy arm), had an increase in the score. No patient had an increase in score to a clinically significant level, usually grade 3 or 4. These preliminary results appear to show that 8 Gy in a single fraction can be as effective as 10 Gy in 5 fractions in preventing heterotopic bone in susceptible individuals. Further follow-up of the remaining patients may confirm this.

Female↗
PubMed1990

The relationship of physician assistants to an orthopedic residency program.

In 1979, coincident with a planned decrease in the size of the general surgery training program, the orthopedic department of the senior author's university-affiliated teaching hospital began to employ physician assistants. The intent of using physician assistants was to relieve the two orthopedic residents assigned to the hospital of many service responsibilities and patient care that previously had been rendered by the general surgical residents and interns. The non-M.D. physician assistants record a comprehensive past and present medical history, carry out physical exams, and assist at surgery. They are directly under the supervision of and responsible to the attending surgeon. It was hoped the addition of these individuals will help maintain a quality educational experience for the orthopedic residents. The general response to the use of physician assistants in this affiliated hospital has been favorable.

Hospital Bed Capacity, 300 to 499↗
PubMed1990

On leadership.

Explore the source record for details and available documents.

Academies and Institutes↗
PubMed1988

Long-term clinical observations and venous functional abnormalities after asymptomatic venous thrombosis following total hip or knee arthroplasty.

The long-term clinical and physiological sequelae of venographically diagnosed, asymptomatic postoperative venous thrombosis were studied in a group of 51 patients following total hip or total knee arthroplasty. After a mean follow-up period of 49.7 months, the patients were recalled for interview, physical examination, air plethysmography (APG), and photoplethysmography (PPG). At the time of follow-up examination, legs with prior postoperative venous thrombosis were not more likely to have clinical findings of deep venous insufficiency than legs with a negative venogram. Abnormal venous emptying, as measured by APG, was significantly correlated (p less than 0.005) with postoperative venous thrombosis and was found in patients with both proximal and calf vein thrombi, but was not clearly associated with symptoms. There was, however, a significant correlation (p less than 0.0005) between clinical findings of venous insufficiency and incompetent valves, as reflected by rapid refilling time after exercise shown by PPG. The findings indicate that asymptomatic postoperative venous thrombosis involving calf or proximal veins can lead to abnormal vein function, but is not closely correlated with later development of symptoms. These observations also suggest that symptomatic venous insufficiency is more closely associated with calf vein valve incompetence than with proximal vein obstruction.

Aged↗
PubMed1987

Prevention of heterotopic bone formation with early post operative irradiation in high risk patients undergoing total hip arthroplasty: comparison of 10.00 Gy vs 20.00 Gy schedules.

Prior studies have demonstrated the effectiveness of postoperative radiation therapy (RT) to the hip area following total hip replacement (THR) surgery in preventing the development of heterotopic bone formation in patients considered to be at high risk for development of this complication. Previously, patients received 20.00 Gy in 10 fractions (fx) over 2 weeks, beginning as soon postop as medically feasible (usually post-op day 2). In an effort to reduce hospital stay and risk of secondary malignancy, a prospective treatment program was initiated April 1982 using a reduced dose of 10.00 Gy in 5 fx over 5-7 days. As of February 1984, 46 consecutive hips determined to be at high risk were treated with this reduced dose. Prior studies have demonstrated that heterotopic bone is always radiographically evident by 8 weeks. Of the 46 hips, 41 had been evaluated with the minimum required 8 week follow-up X ray. Twenty-five of these hips, 61%, had a mean long term follow-up of 12 months. Our historical control group, consisting of 54 consecutive high risk post-THR's, was shown to have a 68.5% incidence of heterotopic bone. The 20.00 Gy group, when RT was started by post-op day 5, demonstrated a 3.2% incidence, compared to 4.9% in the 10.00 Gy group. Complication rates were also comparable in the two RT groups, 19.4% and 7.3% respectively; 10.00 Gy is apparently as effective as 20.00 Gy in preventing heterotopic bone formation in high risk post-THR patients.

Adult↗
PubMed1987

Prevention of venous thromboembolism.

Pulmonary embolism is still the largest single cause of postoperative mortality (1%-3%) from major reconstructive lower extremity joint surgery. It is imperative that the surgeon who deals with trauma and musculoskeletal disorders be informed about the prevention of venous thromboembolic disease, recognize the magnitude of the problem, and then take effective steps. Attention must be given to the use of physical methods and the administration of effective antithrombotic agents, including anticoagulants and antiplatelet agents as well as combination agents, to prevent thromboembolic disease.

Humans↗
PubMed1986

Lower risk of thromboembolic disease after total hip replacement with non-cemented than with cemented prostheses.

During the course of a prospective, randomised trial comparing dextran 40 with antithrombin III plus heparin as prophylaxis against thrombosis after total hip replacement, an unexpectedly low incidence of postoperative thromboembolic disease was found in patients receiving non-cemented (0 of 23) rather than cemented prostheses (4 of 13, 31%). Despite the small number of patients, the difference was significant and necessitated modification of the protocol. These preliminary findings suggest that the type of hip replacement used was more important than the type of antithrombotic medication in preventing venous thrombosis and pulmonary embolism.

Adult↗
PubMed1986

Biologic fixation.

One of the major problems of implant surgery is the failure of the bone-cement interface. Because of such failures, observed with increasing frequency with the passage of time, biologic fixation of total joint implants by means of bone ingrowth has become the focus of considerable interest among orthopedic surgeons. Actual bone ingrowth has been demonstrated into porous metals, resulting in a strong interface between metal and bone. Many clinical trials of biologic fixation, including endoprostheses and total hip, shoulder, and knee prostheses, are being conducted. The brief experience of such fixation in humans supports the hypothesis that bone ingrowth will provide stable fixation for load-bearing prostheses. Many questions remain to be answered about biologic fixation and the burden that falls upon the clinical scientist to identify the proper niche for this process in the care of the musculoskeletal patient.

Bone Cements↗
PubMed1986

The Robert Jones bandage.

A bulky compression dressing (the Robert Jones bandage) is often used by orthopaedic surgeons. We have reviewed its history and monitored intramuscular compartment pressure under it after total knee replacement. We found that it increased compartment pressure and helped to reduce bleeding, tissue oedema and the size of effusions and haemarthroses.

Bandages↗
PubMed1986

The prevention of heterotopic ossification in high-risk patients by low-dose radiation therapy after total hip arthroplasty.

A prospective study was done to evaluate the efficacy of treatment with 1,000 rads of radiation in the prevention of heterotopic ossification after total hip arthroplasty in patients who are at high risk. In a previous prospective study, patients who were at high risk for heterotopic ossification after total hip arthroplasty were identified and an effective regimen for its prevention was established. It was demonstrated that treatment with 2,000 rads of radiation that was initiated within four days after the total hip arthroplasty was highly effective in the prevention of heterotopic ossification and in the prevention of recurrence after resection of existing ossification. In the present study, 1,000 rads of radiation was administered in increments of 200 rads over a period of five to seven days and was as effective as treatment with 2,000 rads. The protocol of 1,000 rads is preferable because it reduces the risk of malignancy and the duration of hospitalization.

Aged↗