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Biomedical subjects

T J Slooff

Publications and source records attributed to T J Slooff.

At least 55 records · Page 3Linked to original sources
PubMed1991

Antibiotic use after cefuroxime prophylaxis in hip and knee joint replacement.

The amount of additional antibiotics measured by defined daily dose (DDD) methods after 2651 hip and 362 knee replacements was assessed after prophylaxis with one or three doses (1502/1511 patients) of cefuroxime. No differences were observed between the two regimens with respect to total amount, type, indication, and duration of additional antibiotics. The incidence of joint sepsis did not differ significantly between the two trial arms, but the sample was too small for definite conclusions. There were 11.4 DDD/100 bed days of additional antibiotics used in 21% of patients after hip replacement and 15.7 DDD/100 bed days in 31% after knee replacement. For wound problems, 3.8 and 6.9 DDD/100 bed days were given in the hip- and knee-replacement groups. For distant infection, 6.5 DDD/100 bed days was administered in both groups. Duration of therapy varied only in relation to indication. Prescribed were penicillins (43% to 50%), sulfonamides (18%), cephalosporins (10% to 16%), and nitrofurantoin (8% to 13%); drug use was related to the type of infection.

Aged↗
PubMed1991

Girdlestone's pseudarthrosis after removal of a total hip prosthesis; a retrospective study of 40 patients.

In case of irreversible failed total hip replacement, a Girdlestone operation is sometimes the obvious solution: excision of cement and prosthesis without attempting a new hip replacement. Reasons for not implanting a new prosthesis are severe loss of bone stock, the risk of recurrent infection, or poor general condition. A clinical follow-up study was performed on 40 patients who underwent a Girdlestone hip procedure using the following criteria: pain, walking distance and the use of a walking support. The mean follow-up was 4.9 years. Postoperatively 33 of 40 patients had less pain compared with the situation before the operation. Sixteen patients walked more than 500 m, 13 patients walked 200-500 m and 11 patients walked less than 200 m, of whom 4 were wheelchair bound. The objective result was good in 40% of the patients, moderate in 42.5%, and bad in 17.5%. Subjectively 62.5% were satisfied. A Girdlestone arthroplasty after loosening of the hip prosthesis was a satisfying solution in most cases.

Adult↗
PubMed1991

Heterotopic ossification following total hip arthroplasty: a review.

Heterotopic ossification is the most frequent complication of total hip arthroplasty. When formed in the para-articular tissues, it may cause pain and restriction of hip motion. The present article extensively reviews the current literature on heterotopic ossification following total hip arthroplasty with regard to epidemiologic factors, clinical presentation and possible pathogenesis. Preventive measures are emphasized. Postoperative treatment with radiation and nonsteroidal antiinflammatory drugs have yielded good results in the prevention of heterotopic ossification. On the other hand, biophosphonates were ineffective. In comparison with radiation therapy, prophylaxis with nonsteroidal antiinflammatory drugs gave better results. Further research is still needed to define the most effective and safe medication regimen.

Aged↗
PubMed1991

The effect of biphosphonate on induced heterotopic bone.

HEBP (1-hydroxy, ethylidene-1, 1-biphosphonate) inhibited mineralization and was observed in matrix-induced heterotopic bone in rabbits. In one group of rabbits, HEBP was administered continuously until sacrifice 20 weeks after the operation. Another group of animals received HEBP for the first four weeks only. The effect of HEBP on de novo bone formation was determined by histologic and biochemical analyses. Implant alkaline and acid phosphatase levels and implant calcium and phosphate contents were measured. The implants of HEBP-treated animals showed diminished implant resorption and, at the same time, formation of atypical osteoid tissue. Quantitative measurements revealed a decrease of acid phosphatase activity, whereas implant alkaline phosphatase activity was unaffected. The mineralization, as depicted by the implant calcium and phosphate content, was almost completely inhibited during HEBP-administration. These effects were completely reversible after the withdrawal of the drug. Remineralization began directly after discontinuation, and recovered only 12 weeks later. The results of this study confirm reports that HEBP cannot prevent the formation of heterotopic ossification. The only effect would be a delay of mineralization during its administration.

Alkaline Phosphatase↗
PubMed1990

Post-loosening mechanical behavior of femoral resurfacing prostheses.

The survival rate of femoral surface replacements has been low relative to conventional total hip replacements. The purpose of this investigation was to determine whether the early clinical loosening can be explained by mechanical causes. Using linear and nonlinear finite element methods, the pre- and post-failure load-transfer characteristics of the femoral surface replacement were analysed, and stress patterns and relative motions at the implant/bone interface were evaluated for a particular hip-loading cycle. Using histology of revision material as a guideline, implant loosening, bone resorption and fibrous interface formation were introduced in the model and their mechanical consequences analysed. The results suggest that the high failure rates are not correlated directly with the chances for primary mechanical failure of the implant-bone interface, but rather indirectly with the sensitivity of the implant design to implant loosening and the propagation of bone resorption and fibrous tissue formation. This mechanism appears to be governed by the proliferation of relative motions between implant and bone. We conclude that the 'secondary stability' of implants in general and their capacity to obtain a stable post-loosening configuration is an important design criterion for long-term survival.

Bone Cements↗
PubMed1990

Late pulmonary metastases from chondroblastoma of the distal femur. A case report.

A patient treated with curettage and bone grafting for a chondroblastoma of the distal femur sustained a pathologic fracture after a local recurrence. He then underwent a local, radical resection and an arthrodesis of the knee. Ten years after the first operation, pulmonary metastases were found, for which he underwent a metastasectomy (thoracotomy). At the latest follow-up, 1 year later there were no signs of tumor.

Adult↗
PubMed1990

Prosthesis-related infection. Etiology, prophylaxis and diagnosis (a review).

The recent literature concerning prosthesis-related infection is reviewed with respect to etiology, prophylaxis and diagnosis. Most prosthesis-related infections are initiated during operation by contamination with bacteria-carrying particles from the air as a result of dispersion of skin scales from individuals in the operating room. A small number of infections are caused by hematogenous seeding of bacteria. Glycocalyx, a slime layer produced by bacteria, plays an important role in the pathogenesis of infections, especially in the presence of biomaterial. Clean-air systems in combination with perioperative systemic antibiotics reduce prosthesis-related infections from 3 or 4 per cent to a few per thousand. The use of antibiotic-loaded bone cement is advised in high risk patients although further evaluation is needed. Physical examination of the patient, laboratory tests such as the E.S.R. and C-reactive protein, serial radiograms, isotope scanning techniques and joint aspiration can all help diagnose prosthesis-related infection. However definitive diagnosis is possible only by culturing several samples of material obtained from the interface during revision operation. A perioperative frozen section of interface tissue showing acute (more than 5 leucocytes per field) or severe chronic (more than 50 lymphocytes) inflammation is highly suggestive of sepsis.

Anti-Bacterial Agents↗
PubMed1989

The heel-tip test for restricted tarsal motion.

We describe a simple test that selectively reveals restricted tarsal motion. From functional anatomic data, it is evident that talocalcaneal motion, being essential for intrinsic tarsal mobility, is correlated with rotation of the tibia when tested in a standing person. When supination of the weight-bearing foot generates only a limited external rotation of the tibia, tarsal pathology must be assumed. In 9 feet with a talocalcaneal coalition, axial tibial rotation with the heel-tip test averaged only 8.4 degrees in contrast to an average rotation of 27 degrees in 60 control feet.

Adolescent↗
PubMed1989

Plain radiographs inadequate for evaluation of the cement-bone interface in the hip prosthesis. A cadaver study of femoral stems.

To determine whether plain radiographs accurately represent the true cement-bone interlock, a comparison was made between radiographs and macroscopic morphology on cross sections of 11 human femora into which a cemented endoprosthesis had been inserted. Four femora had been retrieved postmortem from patients with a hip arthroplasty, and seven cadaver femora were cemented under varying conditions. All the femora were radiographed and then cut for macroscopic inspection of the cement-bone interface with respect to gross interposition, depth of cement penetration, integrity of the bone bed, and lamellation of the cement.

Bone Cements↗
PubMed1988

Effects of preparation techniques on the porosity of acrylic cements.

We investigated four acrylic cement preparation techniques for their effects on cement porosity: hand mixing, pressurization in a pneumatic pistol, centrifugation, and vacuum mixing. All the techniques were tested on three types of cement with different viscosity characteristics. The best results were obtained with vacuum mixing using a newly designed experimental system, yielding porosity reductions of 60-80 percent relative to hand mixing. Vacuum mixing with a commercial system was also effective, but to a somewhat lesser extent. Pressurization and centrifugation had no substantial effect on the overall porosity. Centrifugation led to considerable nonuniformity in the distribution of pores and additives.

Bone Cements↗
PubMed1988

Vascular changes following hip arthroplasty. The femur in goats studied with and without cementation.

We studied two groups of 6 adult female African pygmy goats, which received cemented or uncemented femoral endoprostheses in their right hip. One additional goat was used for in vivo angiography preoperatively and postoperatively. The blood supply to the proximal femur at a macroscopic level was not severed by the operation. Until the 6th postoperative week, the animals were killed at weekly intervals. Microangiography and fluorescence microscopy revealed that rapid revascularization of the metaphyseal trabecular bone in the vicinity of the implants occurred as early as the first postoperative week in both groups. However, in general, the revascularization of the bone around the uncemented prostheses occurred more rapidly, resulting in earlier bone remodeling when compared with the cemented group. Surprisingly, the apposition of periosteal bone was longer lasting and more intensive in the uncemented group, particularly at the metaphyseal level. We suggest that this phenomenon may be enhanced by mechanical stimuli; the restoration of function was delayed in the noncemented goats.

Angiography↗
PubMed1987

Accuracy and reproducibility of instrumented knee-drawer tests.

Instrumented devices for knee-drawer tests have become popular in orthopaedics relatively recently. The objective of the present study was to document the effects of several parameters on the accuracy and reproducibility of anterior-posterior (AP) drawer measurements. An instrumented knee-drawer tester for AP laxity evaluations was constructed, based on the differential displacement method, measuring shifts of the tuberosity relative to the patella. The accuracy of the AP-shift was determined with the parallel use of a highly accurate roentgen stereo photogrammetric (RSP) measurement system on two postmortem leg specimens. The effects of relative motion between patella and femur were negligible. In addition to AP shifts, significant knee flexion and tibial rotations occurred, although the foot and the thigh were fixed as well as possible. The differential displacement method was effective in circumventing this problem. The accuracy of the AP shift was greater than 10%. The reproducibility of the AP drawer parameters (shifts and compliances) was determined in normal subjects and patients. Tests were made to evaluate the effects of different observers, time sequences, and different days. In addition, effects of muscle relaxation were studied. Overall, the shift parameters at different forces were found to be reproducible to between 5 and 15%. The slopes (compliances) of the laxity curves, at different forces, were found to be reproducible between 20 and 40%. The reproducibility was principally affected by deviations in the subject positioning procedure.

Biomechanical Phenomena↗
PubMed1987

Adaptive bone-remodeling theory applied to prosthetic-design analysis.

The subject of this article is the development and application of computer-simulation methods to predict stress-related adaptive bone remodeling, in accordance with 'Wolff's Law'. These models are based on the Finite Element Method (FEM) in combination with numerical formulations of adaptive bone-remodeling theories. In the adaptive remodeling models presented, the Strain Energy Density (SED) is used as a feed-back control variable to determine shape or bone density adaptations to alternative functional requirements, whereby homeostatic SED distribution is assumed as the remodeling objective. These models are applied to investigate the relation between 'stress shielding' and bone resorption in the femoral cortex around intramedullary prostheses, such as used in Total Hip Arthroplasty (THA). It is shown that the amount of bone resorption depends mainly on the rigidity and the bonding characteristics of the implant. Homeostatic SED can be obtained when the resorption process occurs at the periosteal surface, rather than inside the cortex, provided that the stem is adequately flexible.

Adaptation, Physiological↗
PubMed1986

The use of subtraction arthrography in total hip arthroplasties.

The results of plain film radiography and subtraction arthrography in 24 patients prior to revision surgery for a loosened total hip arthroplasty (T.H.A.) were compared with operative findings. Loosening of both the acetabular and the femoral components was evaluated. In plain film radiography the overall accuracy for evidence of loosening in 22 acetabular and 23 femoral components was 58%. The overall accuracy with arthrography was 93%. Three results were false-negatives; arthrography showing no evidence of loosening, while the arthroplasty was found to be loose on surgical evaluation. The results of this study are compared with findings reported in the literature. Arthrography was performed by a lateral puncture technique. There were no complications. The use of the puncture technique has not been described previously. The extent of contrast leakage into the interfaces is described and discussed.

Adult↗