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Biomedical subjects

K Knutson

Publications and source records attributed to K Knutson.

At least 55 records · Page 3Linked to original sources
PubMed1986

Revision of infected knee arthroplasty.

Sixteen infected knee arthroplasties were revised and followed for 5 (1-10) years. There were nine recurrences of infections, but in one of these a second revision was successfully carried out. The remaining seven revisions resulted in only four functioning prostheses. The results were poor for hinged and stabilized prostheses for which arthrodesis, after eradication of the infection, is recommended. Infected compartmental prostheses with good bone stock could be treated with a two-stage procedure using tricompartmental revision prostheses.

Aged↗
PubMed1986

The functional message behavior inventory. Linking nursing action with health care outcomes.

In an era where issues concerning cost and quality of care are constantly raised, it will be increasingly important that expanded-role nurses be able to define their unique contributions to primary care. This will require nurses to self-inventory their nursing processes and conduct research that serves to link nursing action processes to health care outcomes. In order to lay the groundwork for accomplishing this goal, this article provides a brief assessment of the strengths and limitations of an existing primary care process measure (the nurse practitioner rating form), and furnishes a conceptual framework for constructing an alternative process measure--the functional message behavior inventory.

Communication↗
PubMed1986

Loosening of the porous coating of bicompartmental prostheses in patients with rheumatoid arthritis.

Thirty-four porous-coated anatomical (PCA) total knee arthroplasties in twenty-eight patients with rheumatoid arthritis were followed for an average of seventeen months. In these thirty-four knees, twenty-three tibial and fifteen femoral components were cemented. The rest were uncemented. At follow-up, more than half of the knees (nineteen of thirty-four) showed radiographic evidence of displacement of some of the beads from the porous coating. In fourteen knees the beads loosened more than three months postoperatively, and all of these knees had a radiolucent zone. Six knees had beads within the joint. Eight of nine non-cemented tibial components (excluding one tibial component) and five of the nineteen femoral components that were not cemented showed late loosening of beads (after three months). This study indicates that the metallurgical technique for porous coating with heat-sintered cobalt-chromium beads does not produce a coating that is sufficiently strong to prevent loosening in the case of the porous-coated anatomical prosthesis. The long-term clinical relevance of our findings is unclear. The mechanical strength of the porous coating on the prosthetic surface should be improved and the prosthesis should be tested in limited clinical studies before cementless fixation can be recommended.

Adult↗
PubMed1985

Arthrodesis for failed knee arthroplasty. A report of 20 cases.

Twenty consecutive patients treated by arthrodesis for failed knee arthroplasty are reviewed. Eight hinged, five stabilised and seven compartmental prostheses were removed, for infection (15 cases), loosening (4) and instability (1). One patient refused a second-stage operation but the remainder gained sound fusion. Infected knees had a two-stage procedure with temporary insertion of gentamicin-loaded beads after removal of the prosthesis; all infections healed. Six arthrodeses using a Hoffmann-Vidal external fixator resulted in two temporary failures. One Ace-Fischer external fixation was successful. Of 10 primary attempts at arthrodesis with an intramedullary Küntscher nail, nine were successful; the tenth fused after two more attempts by the same method. The two failures of external fixation and two failures after Charnley single-frame compression done elsewhere were successfully fused with intramedullary nails. Delayed union in three cases fused after prolonged fixation and repeated bone grafts. The indications for and methods of arthrodesis after failed knee arthroplasty are discussed.

Aged↗
PubMed1985

Survival of knee arthroplasties for rheumatoid arthritis.

During a 15-year period, 498 primary knee arthroplasties for chronic rheumatoid and related arthritides were performed. Ninety arthroplasties where prosthetic components were added, removed or replaced were recorded as failures. Eighty-one revisions were exchange arthroplasties, eight attempted arthrodeses and one an above-the-knee amputation. Survival rates were calculated with a life table technique. The cumulative 5-year survival rate was 76 per cent for tibial hemiprostheses, 78 per cent for unicompartment prostheses, 100 per cent for tricompartment prostheses, 87 per cent for stabilized prostheses and 84 per cent for hinge prostheses. Continuous deterioration was observed in the tibial hemiprostheses. The improved surgical technique, with guide instruments and release procedures for better alignment and stability, and to some extent the improved prosthetic design may explain the good early results with tricompartment prostheses.

Adolescent↗
PubMed1984

Arthrodesis after failed knee arthroplasty. A nationwide multicenter investigation of 91 cases.

Ninety-one patients with attempted arthrodesis after failed knee arthroplasty were identified in a prospective nationwide study of knee arthroplasties performed from October 1975 through January 1982 in Sweden. The study included 43 hinged or stabilized, 34 bi- or tricompartment, and 14 unicompartment endoprostheses. Three-fourths of the failures were caused by infections. At follow-up evaluation, two patients had expired from infection and four patients had amputations. Fusion was achieved in only 50% of 108 attempts in 91 knees. Patients with unstable joints had limited function. The fusion rate was relatively high after unicompartment endoprostheses, in cases with sustained rigid fixation, or in cases where infection was brought under control at arthrodesis. Rigid fixation was best achieved with an external double frame or an intramedullary nail. Repeated attempts were worthwhile. Removal of all foreign material, eradication of the infectious lesion, and an arthrodesis performed in a one- or two-stage procedure with insertion of gentamicin beads seemed to be the best way to combat infection. The treatment of prosthetic failures should be referred to centers with special interest in knee arthroplasty.

Adult↗
PubMed1984

Stability of external fixators used for knee arthrodesis after failed knee arthroplasty.

Secondary arthrodesis as treatment for failed knee arthroplasty is being used increasingly. The usual method is sustained rigid external fixation. The fusion rate is low in cases with considerable metaphyseal bone loss and poor bone quality. Currently, the Hoffmann- Vidal fixator or comparable designs are preferred to the less stable Charnley single frame fixator. The standard Hoffmann- Vidal device uses only transverse percutaneous fixating pins and gives an anteroposterior bending stiffness that is considerably lower than the lateral bending stiffness. In the present study, external fixators were tested for stability in a material testing machine under standardized conditions using synthetic bones. The anteroposterior bending stiffness was significantly improved when sagittal pins connected to a ventral compression rod were added to a Hoffmann- Vidal fixator. Stiffness was still more improved when sagittal pins were connected to ventral frames as in a modification of the Hoffmann- Vidal or the similar Ace-Fischer fixator.

Arthrodesis↗
PubMed1983

Nerve palsy after knee arthroplasty in patients with rheumatoid arthritis.

Forty-two consecutive knee arthroplasties on rheumatoid knees (19 Attenborough, 20 Total Condylar, 3 Marmor) were examined pre- and postoperatively for signs of below-the-knee nerve lesions. Sixteen of these knees were also studied neurophysiologically (EMG). Four patients (knees) had peroneal nerve palsy, three early and one late. Three further knees had only EMG signs of nerve lesion. Predisposing factor was correction of flexion contracture of more than 10 degrees and especially when combined with varus change in alignment. Preoperative EMG could not predict nerve lesion.

Action Potentials↗
PubMed1981

Deformation and loosening of the tibial component in knee arthroplasty with unicompartmental endoprostheses.

Roentgenological signs of deformation and loosening of the tibial component in knee arthroplasties with unicompartmental endoprostheses occurred in one-third of 87 rheumatoid (RA) knees within 2 years and in one-fifth of 107 osteoarthritic (OA) knees within 3 years after the operation. Compared with thicker components significantly more 6 mm components in RA, and 6 and 9 mm components in OA became deformed and loose. There was no difference in the clinical assessment of the knees with and without deformed tibial components. Reoperations were recorded during an extended follow-up. In the group with initially asymptomatic loosening twelve RA knees within four and a half years and three OA knees within four years developed pain on weight-bearing and had to be reoperated. One patient (OA) had loose components without any roentgenological signs; the loosening was first discovered when the unoperated compartment was revised because of secondary osteoarthrosis. Knees fitted with 6 mm components more often required reoperation because of loosening than did those with thicker components.

Adult↗