Search PubMed⌕ Search

Biomedical subjects

W H Thomas

Publications and source records attributed to W H Thomas.

At least 37 records · Page 2Linked to original sources
PubMed1985

Computed tomography of the hindfoot with rheumatoid arthritis.

We are performing direct, coronally oriented computed tomographic (CT) scans of the subtalar joint in patients with rheumatoid arthritis. To date, 16 examinations have been performed in 14 patients, 5 of whom were scheduled to undergo subtalar arthrodesis. Scans were 4-7-mm thick and spanned the length of the subtalar joint. CT scans depicted and localized subtalar abnormalities clearly and precisely. On CT scans, patients showed a characteristic constellation of abnormalities including: soft tissue swelling, cartilage space narrowing, bony erosions, and a pes planovalgus alignment abnormality (consisting of increased heel valgus angulation, and a tendency toward flattening of the sustentaculum tali, and medial and downward slippage of the talar head). The clarity of the CT images facilitated the surgeon's pre- and postoperative evaluation. In particular, it was easy to plan the correction of the valgus deformity, anticipate any special requirements for reinforcing the articular surfaces, and assess the results of surgery. We conclude that coronal CT scans clearly demonstrate abnormalities and help the surgeon evaluate the rheumatoid hindfoot.

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

Enhanced response of the Salmonella mutagenicity test to ionizing radiations.

Gamma-ray-induced reversions in the Ames Salmonella tester strain TA2638 have been studied for their dependence on a number of experimental parameters. It is shown that exposure to ionizing radiations soon after plating is not the procedure that yields results which correspond to those obtained in the standard utilization of the test with chemical mutagens. The ability to detect mutants is improved by irradiation 6 hr after the beginning of the incubation of the plated bacteria. This procedure has the double advantage of a markedly increased ratio of radiation-induced to spontaneous revertants and of resulting in substantial insensitivity to fluctuations in the number of bacteria initially plated. The reversion-doubling dose so obtained is 1.3 Gy; i.e., it is sufficiently small to disregard inactivation of the bacteria.

Cobalt Radioisotopes↗
PubMed1984

Computed tomography of the hindfoot.

This investigation used computed tomography (CT) to study the normal anatomy of the hindfoot and to demonstrate abnormalities in patients with rheumatoid arthritis, pes planovalgus , old trauma, and soft-tissue masses. The hindfeet of 10 normal volunteers and 17 patients were scanned in the coronal and axial transverse planes. The articular surfaces of the tibia, talus, and calcaneus were assessed, as were the relationships of each bone to the others. Normal subjects had markedly symmetrical hindfeet . The "heel valgus angle" (relating the calcaneus to the tibia) was 5.2 +/- 1.6 degrees (mean +/- standard error of the mean). The "sustentacular angle" (indicating the angle of elevation of the sustentaculum tali at the midsubtalar joint) was 18.3 +/- 1.3 degrees. The "medial offset" of the talar head with respect to the calcaneus (measured at the anterior subtalar joint) averaged 5.2 +/- 1.8 mm. Patients with rheumatoid arthritis had erosions involving both sides of the subtalar joint, leading to talocalcaneal alignment abnormalities. In patients with pes planovalgus the heel valgus angle was greater and the elevation of sustentaculum tali lower in the foot that was most severely affected. Bony talocalcaneal fusions, fractures, and the erosions of pigmented villonodular synovitis were detected on CT. The pattern of postoperative bone healing after attempted subtalar fusion could be demonstrated. We conclude that CT is a useful tool for pre- and postoperative evaluation of the hindfoot.

Adult↗
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↗
PubMed1982

Prognostic features of atlantoaxial subluxation in rheumatoid arthritis patients.

The clinical and radiographic findings of 194 patients with rheumatoid arthritis and atlantoaxial (C1-C2) subluxation and/or atlantoaxial impaction (AAI) were reviewed. The condition of most patients with C1-C2 alignment abnormalities remained unchanged or became worse with time (i.e., the misalignment became fixed, subluxation increased, or AAI developed). The chance of developing upper cervical cord compression was not related to worsening per se, but to the degree of deformity. Upper spinal cord compression developed more often in men; when C1-C2 subluxation was greater than 9 mm; and in the presence of atlantoaxial impaction. The presence of lateral C1-C2 subluxation probably also contributes to the development of upper spinal cord compression. Settling of the skull and C1 onto C2 (AAI) were considered to be present when the anterior arch of C1 was abnormally low in relation to C2.

Adult↗
PubMed1982

The kinematic rotating hinge: biomechanics and clinical application.

The Kinematic rotating hinge offers a solution as a salvage procedure for severely deformed and unstable "end-stage" knees. Excellent short-term results in terms of pain relief can be achieved, and motion up to 130 degrees is possible, depending on the condition of the quadriceps mechanism and the extent of scarring from previous operations. Care must be taken to avoid cortical penetration, especially in cases of hinge revisions, osteoporosis, thin-walled bones, and the presence of old cement. As with any total knee arthroplasty, care must be taken to achieve optimal rotatory alignment of the tibia beneath the femur to guarantee good patellar tracking.

Adult↗
PubMed1980

Capitellocondylar total elbow arthroplasty.

Sixty-nine non-constrained capitellocondylar metal-to-plastic total elbow-replacement prostheses were implanted in sixty-four patients with rheumatoid arthritis. These patients were followed for an average of 3.5 years. Postoperative flexion and pronation were significantly improved, but no significant increase in postoperative extension or supination could be demonstrated. Based on a rating system evaluating pain and function, there were 87 per cent good or excellent results. The complication rate based on the total number of prostheses implanted was 39 per cent. Eight patients required revision of the arthroplasty: four for dislocation of the prosthesis, two for sepsis, one for loosening, and one for a fracture. Eight other asymptomatic patients showed minimum radiolucent lines adjacent to the ulnar component. No patient demonstrated radiolucent lines adjacent to the humeral component.

Adolescent↗
PubMed1979

Clinical study of total ankle replacement with gait analysis. A preliminary report.

Twenty-one ankle replacements in nineteen patients after an average follow-up of 14.7 months were analyzed with respect to their history, physical and roentgenographic findings, and gait analysis. The relief of pain and functional improvement after operation were disappointing compared with the results of prosthetic replacement in other joints and were not related to early complications, age, diagnosis, or the prosthesis used. Muscle weakness about the ankle, especially of the plantar flexors, was a prominent finding and appeared to cause abnormal patterns of gait and of ankle motion. The frequency of progressively increasing radiolucent lines was 88 per cent and of late loosening, 10 per cent. These results suggest a need for more emphasis on postoperative rehabilitation and on the uncertainty of this procedure at its present stage of development.

Activities of Daily Living↗
PubMed1978

Total hip replacement with and without osteotomy of the greater trochanter. Clinical and biomechanical comparisons in the same patients.

Twelve patients with bilateral hip replacement, one side performed with a trochanteric osteotomy and the other without osteotomy, were analyzed by review of the clinical records, the findings on physical examination, preoperative and postoperative Harris hip scores, each patient's evaluation, biomechanical analysis of the preoperative and postoperative roentgenograms of the hips and pelvis, and force-plate gait analysis. All operations yielded good results clinically but the majority of patients preferred the replacement done without osteotomy. Blood loss and trochanteric bursitis were greater problems in patients who had an osteotomy. There were no differences between the two groups in the postoperative Harris scores or in the biomechanical measurements made on the preoperative and postoperative roentgenograms except for the change in the abductor-muscle length. Changes in this parameter correlated well with the patients' symptoms and clinical findings.

Adult↗
PubMed1977

X-ray photoelectron spectrometry of copper-thiouracil complexes.

X-ray photoelectron spectrometry was applied to evaluate the correct oxidation number of copper in complexes with 2-thiouracil, 6-amino-2-thiouracil and 6-methyl-2-thiouracil. Regardless of the mode of preparation exclusively Cu(I) was bound to the different thiouracil compounds, producing one homogeneous signal of the Cu2p3/2 electrons at 932.5 eV. Upon oxidation with H2O2, a typical Cu(II) satellite appeared in the main signal of the Cu2p3/2 level was shifted to higher binding energy values. The reaction of Cu(II) with thioracil yielded identical complexes as above, in which Cu had the formal oxidation state +I. During this reaction portions of the thiouracil were oxidized to 2,2'-dithiobis(4-pyrimidinol) [bis(4-hydroxy-2-pyrimidinyl)disulphide], as seen by the shifted sulphur 2p signals to 163.5 eV. After treating the Cu-thiouracil complexes with H2O2, the simultaneous presence of sulphur species having the oxidation states RStheta (161 eV), RSSR (163.5 eV) and RSOtheta3 (168.5 eV) is indicated by the ESCA signals monitored.

Copper↗
PubMed1977

Conformational changes induced by ionic strength and pH in two bovine myelin basic proteins.

The structures of two biologically different myelin proteins, A1 from the central nervous system and P2 from the peripheral nervous system, were investigated. Both proteins were isolated from nerve tissues. Conformational changes in the homogeneous proteins were examined in aqueous solutions by means of circular dichroism measurements. The secondary structures of both proteins proved to be very stable between pH 2.5 and pH 11.7. Unlike the P2 protein, the A1 protein is stable up to pH 13 without detectable conformational changes. The stereochemistry of the polypeptide chains of both proteins is markedly different in the presence of urea. While the value of theta222 for the A1 protein changes linearly with increasing urea concentration, a sigmoidal curve was obtained for the P2 protein. The observed differences in the dichroic properties of the basic myelin proteins A1 and P2 indicate the possibility of further structure - function correlations.

Animals↗
PubMed1976

Complications of total hip-replacement arthorplasty in patients with rheumatoid arthritis.

During the period 1969 through 1974, 716 total hip-replacement arthorplasties were performed. The results of the surgery in 275 cases of rheumatoid arthritis as regards complications were compared with those in 382 procedures in cases of osteoarthritis. In contrast to the reports of others,the incidence of deep would infection in the two groups was found to be equal. Patients undergoing total hip-replacement arthroplasty as a revision of a previous operation had a substantially increased risk of infection. Patients with rheumatoid arthritis, however, were more subject to certain other complication (intraoperative fracture, difficulties with anesthesia, and malposition of prosthetic components), in addition to the complications that were predictable because of the involvement of multiple joints and the systemic disease process.

Adult↗