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Biomedical subjects

F C Ewald

Publications and source records attributed to F C Ewald.

At least 37 records · Page 2Linked to original sources
PubMed1989

The Knee Society total knee arthroplasty roentgenographic evaluation and scoring system.

A roentgenographic knee evaluation system endorsed by The Knee Society is included in this year's proceedings to encourage uniform reporting of the results of total knee arthroplasty. No rating system is ideal, but if many surgeons and centers use the same reporting system, then relative comparisons will at least become possible. Agreement on a new system by many experienced surgeons and institutions with a large clinical volume represents a sacrifice because old rating system data will have to be discarded.

Arthrography↗
PubMed1989

Is kinematic total knee replacement better than total hip replacement?

Revision rates, complication rates, and the bone-cement interface reaction of 1,069 condylar total knee replacements were reviewed to help decide if conventional total knee replacement continues to be appropriate for the older low-demand patient. This knee replacement series was also compared with two published series of total hip replacements from the same institution. The conclusions are (1) in medium-term follow-up, total knee replacement is as good as or superior to total hip replacement and (2) based on bone-cement interface analysis, survival of total knee replacement is expected to be superior to conventional total hip replacement ten years postoperatively.

Follow-Up Studies↗
PubMed1988

The current status of total knee replacement.

Total knee replacement has come of age, and long-term results are much better than those for total hip replacement. The designs of the late 1980s have addressed function, mobility, wear, and long-term survival for the young and active. Conventional, cemented knee arthroplasty is highly successful and well represented by the state of the art in the Kinemax total knee replacement prosthesis. This design also has the capability of treating the postseptic knee, the knee that requires extensive bone grafting, and, experimentally, the young, the active, or the overweight patient.

Cementation↗
PubMed1988

Failure of the metal-backed patellar component after total knee replacement.

Twenty-five patients had failure of a metal-backed patellar component after total knee replacement. Five manufacturers and seven designs were involved. There was no apparent correlation between failure of the component and the age or sex of the patient, the diagnosis, the use of cement, the femorotibial alignment, or the use of lateral release. The patients in whom the patellar implant failed were relatively heavy, and the diagnosis in most of them was osteoarthritis. The failure was due to one of two mechanisms: wear or fracture, or both, of the polyethylene over the edge of the metal backing (eighteen components), or dissociation of the polyethylene or the base-plate, or both, from the anchoring pegs (seven components). In many of the patients, failure of the component was not suspected before arthrotomy. The failure led to considerable wear of the femoral component in eleven patients and to metal-induced synovitis in twenty-three. We concluded that metal backing may predispose the patellar component to a small but important likelihood of failure, and we urge caution in choosing a metal-backed patellar implant. Additional research is necessary to improve designs for the patellar component, especially if metal backing is to be used.

Aged↗
PubMed1987

Long-term results of total hip arthroplasty in protrusio acetabuli.

Ninety-three total hip arthroplasties were examined radiographically and clinically to investigate the best method of correction in protrusio acetabuli. Fifty-three percent were treated with cement alone, 36% with mesh or protrusio shell, and 11% with bone graft. Long-term follow-up study revealed a high percentage of immediate and late radiolucent lines. The highest rate of loosening, 50%, occurred in the cement alone group, which had not been corrected to within 10 mm of anatomic position. Sex, cause of protrusio, age at operation, and degree of osteopenia were not significantly different between the groups. The follow-up period was longer in the cement alone group, but this did not account for the excessively high rate of loosening. Correction of the anatomic position in protrusio deformity is vital, whether accomplished with cement, mesh, protrusio shell, or bone graft. Late radiolucent lines are common and do not reliably indicate loosening.

Acetabulum↗
PubMed1987

Radiographic study of Kinematic total knee arthroplasty.

One thousand sixty-nine consecutive cemented Kinematic Condylar total knee arthroplasties performed by one group of orthopaedists were studied. The maximum follow-up period was 7 years. Most patients had rheumatoid arthritis or osteoarthritis, and the average patient age was 67 years (range, 12-90 years). Aseptic revisions for loosening were required for only one tibial component and six patella components. Average postoperative flexion was 2.5-107 degrees. The preoperative to postoperative change in range of flexion was not affected by the tilt angle of the tibial component in the sagittal plane. With the use of external alignment guides, the average postoperative alignment was ideal but the standard deviation was high; the standard deviation and the extremes were lower when intramedullary guides were used. There was a 14% incidence of femoral radiolucency and a 30% incidence of tibial radiolucency, which increased only slightly with time. Most radiolucencies on the tibial side were small and restricted to the extreme edges; rarely did radiolucency occur around the central peg. More than one half of the thicker radiolucencies occurred adjacent to wedge-shaped bone defects that were filled with cement.

Activities of Daily Living↗
PubMed1987

Arthroplasty of the ipsilateral shoulder and elbow in patients who have rheumatoid arthritis.

Over a ten-year period, arthroplasty of the ipsilateral shoulder and elbow was performed in thirty-five extremities of thirty-one patients who had advanced rheumatoid arthritis. The results of the procedures were retrospectively reviewed to determine the appropriate sequence of surgery and the functional results that were obtained. All patients were followed for a minimum of two years after the last arthroplasty. The elbow had been operated on first in twenty-one extremities and the shoulder had been operated on first in fourteen. The time-interval between arthroplasties was significantly longer (p less than 0.005) when the elbow had been operated on first (forty-five compared with 13.4 months). All motion of the elbow and elevation and external rotation of the shoulder improved significantly (p less than 0.005), similar to the improvement in motion that is noted when either joint is operated on alone. Also, there was a highly significant reduction in pain and improvement in function (both, p less than 0.001). Review of the roentgenograms of twenty-three patients demonstrated no humeral fractures or interference in the proper placement of the humeral component of the prosthesis either by the stem of the other prosthesis or by the methylmethacrylate. All of the arthroplasties of the shoulder that were performed as the second arthroplasty were done at least five months after the arthroplasty of the elbow, and no dislocations or subluxations of the components of the elbow prosthesis occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

McKeever metallic hemiarthroplasty of the knee in unicompartmental degenerative arthritis. Long-term clinical follow-up and current indications.

Forty patients with forty-four unicompartmental McKeever metallic uncemented hemiarthroplasties were followed for five to thirteen years (average, eight years). Thirty-nine knees had a medial and five, a lateral arthroplasty. The age at surgery ranged from thirty-two to eight-two years (average, sixty-seven years). At the final follow-up, 70 per cent of the knees were rated as good or excellent. Seventy-nine per cent of the knees in patients who were less than sixty-five years old at the time of surgery were in these categories. Six knees (14 per cent) had required revision to either a unicompartmental or a bicompartmental total knee replacement. The average preoperative and postoperative knee flexion did not change, but knees with initially poor motion improved. The average preoperative flexion contracture of 10 degrees improved postoperatively to 5 degrees. Complications were rare and no cases of infection, peroneal palsy, or clinically detectable phlebitis occurred. Obesity did not seem to adversely affect the outcome. This study indicated that the McKeever unicompartmental metallic hemiarthroplasty can provide an attractive alternative in the treatment of unicompartmental degenerative arthritis when proximal tibial osteotomy is contraindicated or has failed or when the patient is too young, heavy, or active to consider total knee replacement.

Adult↗
PubMed1985

Air in painful total hip arthroplasty: diagnosis and treatment.

A 78-year-old woman presented with a painful total hip arthroplasty five years postoperation. Plain radiographs revealed air in the hip joint. Aspiration of the hip indicated hip sepsis, and arthrogram showed communication of the hip joint with the sigmoid colon. Cultures grew Bacteroides fragilis. Abdominal exploration showed a ruptured diverticulum that decompressed through the sciatic notch into the total hip arthroplasty. A colostomy was performed, and the hip joint was drained and debrided laterally at the same operation. The prosthesis was later removed with all cement, and the hip was converted to a Girdlestone resection. The authors conclude that air or gas shadows in a painful total hip arthroplasty are an ominous finding and mean either joint sepsis with a gas-forming bacteria or communication of the joint with a hollow viscus and sepsis.

Aged↗
PubMed1984

Kinematic total knee replacement.

We reviewed 124 consecutive kinematic condylar total knee replacements (in ninety-one patients) at two to four years postoperatively. One hundred and eleven (90 per cent) were rated as good or excellent. The average active postoperative flexion was 106 degrees (range, 94 to 120 degrees). Twenty-two knees (18 per cent) had incomplete, non-progressive radiolucent lines, less than one millimeter in width, at the tibial bone-cement interface; these were considered insignificant. Restriction of stair-climbing ability in this series appeared to be a function of involvement of multiple joints rather than of patellar replacement, as the rheumatoid patients with resurfaced patellae performed the worst. The osteoarthritic patients with involvement of a single joint performed the best, regardless of whether the patella was resurfaced or not. When compared with a similar series of total knee replacements in which the tibial component was made entirely of plastic, less reaction at the bone-cement interface was found with the metal-backed kinematic tibial component. We suggest that this finding is clinical confirmation of in vitro studies that demonstrated the advantage of metal-backed tibial components. We concluded that this procedure, if meticulously performed, will give predictably good to excellent results with a low complication rate, a good postoperative range of motion, and a favorable-appearing bone-cement interface at two to four years.

Adult↗
PubMed1984

Control of cement penetration in total knee arthroplasty.

A radiographic study of 45 knees immediately and at least two years after operation showed that the average depth of cement penetration was 1.5-3.0 mm at different locations around the interface and that there was a strong inverse relation between the development of radiolucency and initial cement penetration. In laboratory studies of penetration in the upper tibia, penetration was approximately proportional to bone pore diameter and to the square root of the applied pressure and inversely proportional to the time after initial mixing. There was a low correlation of the tensile strength of the cement-bone bond with the depth of penetration, probably due to the variability of the trabecular bone strength. Failure occurred by direct cement pullout or by partial or total fracture through the bone. In light of all factors, the suggested ideal depth of cement penetration is 3-4 mm. This penetration can be achieved by using the left-lift method about four minutes after initial cement mixing, but with some selective prepenetration around the periphery of the tibia.

Biomechanical Phenomena↗
PubMed1983

Total knee arthroplasty in juvenile rheumatoid arthritis.

From 1971 to 1981, total knee arthroplasty was performed on forty-eight knees in twenty-eight patients with juvenile rheumatoid arthritis at the Robert Breck Brigham (now Brigham and Women's) Hospital. Seventeen of these patients, with twenty-nine knee-replacement arthroplasties, were followed for from two to eleven years (average, five years) and are the basis for this study. The patients' ages at operation ranged from thirteen to thirty-nine years (average, twenty-three years). Six patients had undergone total hip arthroplasty prior to admission for total knee replacement, and five patients had a total hip replacement performed while they were hospitalized for the knee arthroplasty. Thirteen patients (twenty-one knees) had significant preoperative pain but only three (five knees) had severe discomfort. Four patients were unable to walk, three were household walkers, and ten were limited community walkers. Preoperative deformities of the knees ranged from 20 degrees of varus angulation to 35 degrees of valgus angulation. The average preoperative flexion deformity was 23 degrees and the arc of motion averaged 45 degrees. At follow-up, twenty of the twenty-one knees that had been significantly painful preoperatively were completely relieved of discomfort. The average arc of motion increased by 34 degrees, while in all but one knee the angular deformity had been corrected to zero to 10 degrees of valgus angulation. All but one patient became a limited or full community walker. Complications included one late deep infection and one posterior tibial subluxation. Four knees required subsequent resurfacing of the patella for treatment of pain. We now routinely resurface the patella in all patients with juvenile rheumatoid arthritis who have a total knee replacement. To date no prosthesis has required revision for loosening. Radiolucency of one millimeter or less about the prosthesis was noted at follow-up in eight (30 per cent) of the knees. As custom-made components were required in twelve of the twenty-nine knees, it is obvious that preoperative planning is crucial in the treatment of these patients. Our recent experience has shown that the use of preoperative and postoperative serial casts aids greatly in the correction of severe flexion deformity of the knee. Postoperative manipulation was required for twenty-one of the twenty-nine knees. Skeletal immaturity was not an absolute contraindication to surgery. We think that our results, which showed a marked improvement in both knee function and in quality of life, make the short and long-term risks of knee-implant surgery well worth taking in this patient population.

Adolescent↗
PubMed1983

Quantitative gait analysis after total knee arthroplasty for monarticular degenerative arthritis.

By quantitative gait analysis, we characterized the functional results of total knee arthroplasty in a group of twelve elderly patients with isolated degenerative arthritis of one knee. All patients had had a standard replacement arthroplasty performed at least two years before the study. In the gait analysis we used high-speed movie cameras synchronized with force platforms and electromyograms to provide kinetic and kinematic data. The data were compared with those obtained from an age-matched control group. In the patients most of the measurements of gait had been restored to normal levels. These measurements included: velocity; stride length; arcs of motion of the hip, knee, and ankle bilaterally; phasic muscle activity; and the amount of mechanical work performed. There were three patterns of external torque across the implants and in the control knee which were comparable in magnitude but varied in relative frequency between the two groups. As compared with the controls, the patients spent approximately 30 per cent more time in double-limb stance and had prolonged cycle times. These findings may have been the result of muscle weakness, neural impairment, or habit, but the cause could not be determined by this study.

Aged↗
PubMed1982

Effects of tibial components on load transfer in the upper tibia.

Knee specimens were loaded in combinations of compression, anteroposterior force, rotational torque, and varus-valgus moment. The strains on the outer surface of the tibia at four levels were determined from strain gauges. Tibial components of the central peg type were cemented in place and the strains again measured for the same loading combinations, thus obtaining comparisons with the normal. Strain readings were also taken around the central pegs. The variables of the tibial components were all-plastic versus a metal tray; short, medium, and long post; and complete versus incomplete upper surface coverage. For varus-valgus or anteroposterior loading, there were high strains due to bending around the proximal part of the plastic stem compared with the metal stem; the metal stem carried a much higher bending moment than did the plastic stem. In direct loading, there was a rim of low-stressed bone around the proximal perimeter for incomplete contact, and a metal stem longer than the standard, transmitted some load directly to the cortex; a plastic stem carried only small axial loads, probably because of its low axial stiffness. Metal backing is not without disadvantages; notably, some load by-passing, cost, and comparatively difficult removal.

Humans↗