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Biomedical subjects

G W Bradley

Publications and source records attributed to G W Bradley.

At least 19 recordsLinked to original sources
PubMed2000

Revision total knee arthroplasty by impaction bone grafting.

The presence of bone loss in a failed total knee arthroplasty can present a significant reconstructive challenge. Experience with the technique of using impacted morselized allograft with revision components having fixed stems is presented. Nineteen knees (21 patients) were reconstructed using impacted bone graft alone in 14 knees, bone graft plus methylmethacrylate in five knees (including one knee in which the replacement failed), and in three knees morselized bone graft was used in conjunction with structural bone allograft. Minimum followup ranged from 6 months to 62 months for the patients in the current series. These patients represent a relatively small, but growing portion of this surgeon's population of patients undergoing revision knee arthroplasty. Patients with large defects were selected for the study. Histologic specimens from the one failed knee arthroplasty revealed viable, incorporated bone graft. Excluding the replacement that failed, the average improvement in Knee Society combined knee and function scores was 87 points. The principles of revision and primary total joint arthroplasty are applied for achieving a stable implant. Specific to this technique, solid support of the implant-graft interface, graft-host bone interface, and the use of a tight, supportive stem is imperative. The author's experience provides additional support for the use of bone grafting techniques in patients with large bone defects who are undergoing revision total knee replacement.

Adult↗
PubMed1998

Can a total knee replacement prosthesis be made entirely of polymers?

We have prospectively studied 63 total knee replacements (TKR) in which the femoral component was polyacetal, and 138 TKRs in which the femoral component was conventional cobalt chrome. The tibial and patellar components were of ultrahigh molecular weight polyethylene (UHMWPE). Patients were followed-up for at least 10 years. In the polyacetal group, a number of patients have died or have been revised, for reasons unrelated to the presence of polyacetal. There were no instances of femoral component fracture, nor failure by wear. One postmortem specimen, retrieved at 9 years after surgery, showed no measurable polyacetal wear and negligible HDP wear. The histology of tissue in contact with polyacetal was indistinguishable from that adjacent to polymethyl methacrylate and UHMWPE in the same knee. We believe that polyacetal could be used for the femoral component of a TKR and that a further trial should be undertaken.

Acetals↗
PubMed1993

Evaluation of wear in an all-polymer total knee replacement. Part 2: clinical evaluation of wear in a polyethylene on polyacetal total knee.

In an effort to improve the long-term result of total joint replacement arthroplasty, we have investigated the use of a polymer-on-polymer articular replacement arthroplasty. Because of their known biocompatibility and previous use in orthopedic surgery, polyethylene and polyacetal (copolymer, Hoechst) were selected. Polyethylene served in its usual role as the concave member of the articulation; polyacetal formed the convex number. Formal wear testing using a multi-channel hip simulator demonstrated superior wear characteristics of the polymer-on-polymer configuration compared to a conventional chrome-cobalt versus polymer (polyethylene) configuration. A clinical series of relatively high-activity patients having a minimum five-year follow-up (N = 26) showed no specific unfavorable reaction to this material combination in a total knee replacement. Given certain potential advantages of polymeric materials, as well as some theoretical disadvantages of metallic materials, a polymer-on-polymer design for a large joint replacement may have some merit.

Acetals↗
PubMed1987

Total prosthetic replacement of ankylosed knees.

Total knee arthroplasty is reliable for achieving pain relief, increasing range of motion, maintaining stability, and improving walking ability. In this study, the results in knees with a preoperative range of motion of 0 were reviewed to determine whether an ankylosed knee can be replaced successfully. In eight of nine knees, the results with regard to pain, stability, and walking ability were good at follow-up evaluations greater than 2 years after operation. Range of motion was also improved in all knees but was still limited. Motion achieved was in a physiologic arc with all knees having full, or nearly full, extension.

Ankylosis↗
PubMed1987

Resurfacing arthroplasty. Femoral head viability.

Although obvious theoretic advantages accrue from resurfacing arthroplasty of the hip, the indications for the procedure are controversial because the failure rate is high and loosening is unacceptably frequent. To determine the role of osteonecrosis in these failures, the viability of bone within the femoral head was determined by histologic examination of bone inside 25 failed femoral resurfacing components. The bone was substantially alive throughout the femoral head in 23 of 25 cases (92%). In two cases, the bone of the femoral head was dead. Both of these hips had clinically failed because of femoral neck fracture. This histologic evaluation indicates that bone death is not an inevitable consequence of femoral head resurfacing and the use of polymethylmethacrylate fixation.

Adult↗
PubMed1983

ICLH surface replacement of the hip. An analysis of the first 10 years.

Clinical experience of the ICLH method of resurfacing the hip now spans 10 years. The first 36 arthroplasties, performed between 1972 and 1974, have been previously reported. This review covers in detail 204 such arthroplasties performed between 1975 and 1979 using a standard operative technique and prosthesis; these hips were consecutive and entirely unselected. Follow-up averaged 3.2 years (range two to six years). Successful hips are comparable to hips successfully replaced with stemmed prostheses. The rates of perioperative complications and failure due to infection, ectopic ossification, fracture of the femoral neck, and dislocation are favourably comparable to rates reported for stemmed total hip arthroplasties. The rate of aseptic loosening (17 per cent) greatly exceeded that found for stemmed total hip arthroplasties. Errors of patient selection, operative technique and prosthetic design have been identified. It is concluded that, although resurfacing arthroplasty of the hip may be an appealing procedure with theoretical advantages in certain instances, patient selection is essential, operative technique is demanding and changes in the design of the prosthesis are required. The procedure is still in evolution and therefore it should not yet be generally employed.

Adult↗
PubMed1983

Revision of failed hip resurfacing.

Resurfacing arthroplasty of the hip is a relatively recent innovation that has theoretic advantages in certain instances. One alleged advantage is "revisability." At the London Hospital 28 resurfaced hips that were converted to stemmed hip arthroplasties have been reviewed. Follow-up periods averaged 2.8 years (range, 1-9 years). Almost 90% of these hips were functioning satisfactorily at the time of review. The data suggest that the result of revising a resurfaced hip may be predictably better than that of revising a stemmed hip arthroplasty.

Aged↗
PubMed1982

Effect of vagotomy on the breathing pattern and exercise ability in emphysematous patients.

1. The potential value of right vagotomy for the relief of breathlessness has been explored in five patients with emphysema. Two patients had symptomatic improvement, two had minor symptomatic improvement, and one was unchanged. 2. Exercise ventilation was not noticeably depressed by unilateral right vagotomy in the two patients investigated fully, but the pattern of breathing was altered. After vagotomy, breathing was deeper, and the rise in the frequency of breathing with exercise was depressed. 3. After right vagotomy the response to rebreathing carbon dioxide also consisted of slower deeper breaths. 4. Right vagotomy sometimes appears to remove an influence preventing slow deep breathing and exacerbating dyspnoea. 5. Results of bilateral pulmonary denervation, attempted in one patient, were complicated by the need for left thoracotomy, which removed any possible beneficial effects.

Aged↗
PubMed1982

Cementless fixation of the tibial component for the ICLH knee.

The use of polymethylmethacrylate bone cement in joint replacement surgery is not without drawbacks. Certain hazards have been appreciated and the bone cement interface may not be as stable in the long run as was once felt. This paper reports the results in 52 knees which were replaced using the uncemented ICLH (Imperial College/London Hospital) tibial component; the average follow up was two years (range six months to four years). The results were compiled with regard to pain as well as clinical examination and X-ray evaluation. The results were comparable to those achieved in knees replaced using bone cement. Roentgenographic evaluation revealed no evidence of loosening nor sinkage of any of these prostheses. Considerations in the development of a knee prosthesis to be utilized without bone cement and the operative technique employed to implant such a prosthesis are presented. The merits of such a system are discussed.

Adult↗
PubMed1982

Observations upon the interface between bone and polymethylmethacrylate cement.

The occurrence of a radiolucent line at the interface of bone and cement in total joint prostheses is a frequently observed, although little understood, phenomenon. Because of an operative technique utilised in instances of bone loss, we have, within a single implant mass used in each of a series of 18 total knee replacements, been able to observe two separate interfaces, one between bone and cement and the other between bone and cobalt chrome. The average period of observation was 32 months. All of the knees except one demonstrated a lucency at the bone-cement interface; only one of the knees had a similar lucency at the bone-CoCr interface. One of the knees was studied histologically. In the light of the universal observation of macrophages at bone-cement interfaces and the recent finding that osteoclasts are derived from macrophages, these observations are significant in relation to the aetiology of bone-cement lucencies.

Adult↗
PubMed1981

Haemolytic anaemia with hypernephroma.

A case is reported of Coombs' positive haemolytic anaemia associated with hypernephroma. The anaemia regressed on removal of the tumour but returned when secondary deposits developed.

Adenocarcinoma↗
PubMed1981

Treatment of the calcaneocavus foot deformity.

The calcaneocavus foot is almost always the result of a neural disorder and subsequent weakness of the triceps surae muscles. It is inexorably progressive, always disabling, and refractory to bracing. Therefore, treatment is directed toward the surgical correction of any existing deformity and the restoration of muscle balance. We developed a treatment approach based on goals and requirements that must be individualized according to the underlying neural disorder, the exact nature of the muscle imbalance, the degree of bone deformity, and the skeletal age of the patient. Nineteen calcaneocavus feet have been treated at our institution since 1958, with follow-up averaging seven and three-quarters years. The objective evaluation of the correction obtained was determined from a ratio computed by measurements on radiographs. All feet were improved according to this raio, although three were not corrected as well as was desired. An effort also was made to establish the amount of functional improvement as it was reflected in improved gait and push-off. These were largely subjective determinations, however, and although all patients demonstrated improved function, the amount of improvement was difficult to quantitate and none had normal function. There was a substatially consistent relationship between the improved objective and subjective result evaluations.

Adolescent↗