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Biomedical subjects

R S Laskin

Publications and source records attributed to R S Laskin.

11 recordsLinked to original sources
PubMed1990

The use of metal-backed patellar prostheses in total knee arthroplasty.

Metal backing of polyethylene prosthesis components decreases deformity of the overlying polyethylene and enhances fixation to the underlying bone. Previous metal-backed patellar designs have often failed, primarily because of implant design and implantation technique. In 451 total knee arthroplasties using metal-backed patellar prostheses, there were no implant failures. The implants were dome shaped and did not have a metal endoskeleton. The component was inset into the patellar bone so that the base plate was below the superficial surface of the bone. These factors maximized polyethylene thickness and prevented wearing through to the metal base plate. The advantage of metal backing is that it strengthens the component and allows for possible biologic ingrowth. In this series, the combination of implant design and implantation technique may have eliminated serious problems seen with other metal-backed patellar implants.

Aged↗
PubMed1990

Total condylar knee replacement in patients who have rheumatoid arthritis. A ten-year follow-up study.

Eighty knee replacements with a total condylar prosthesis in patients who had rheumatoid arthritis were followed for ten years. At ten years, nineteen knees needed revision and sixty-one prostheses were still functioning. The major reasons for revision were loosening of the tibial component or late bacteremic seeding from another site. Radiolucency at the bone-cement interface adjacent to the tibial component was statistically related to malposition of the tibial component. According to the system of The Hospital for Special Surgery, the mean scores were 64 points preoperatively and 85 points postoperatively. Synovitis recurred in only 3 per cent of the knees. When revision, pain, or radiographic evidence of loosening were considered an indication of failure, the ten-year cumulative survival was 75 per cent.

Arthritis, Rheumatoid↗
PubMed1989

Total knee arthroplasty in the presence of large bony defects of the tibia and marked knee instability.

Twenty-six patients with severe tibial bone loss and secondary varus-valgus instability of greater than 20 degrees were treated by total knee arthroplasty using autogeneic bone as a graft in the defect. With proper filling of the resultant flexion and extension spaces, instability was corrected in 22 of the knees. Hospital for Special Surgery rating scores at one, two, and three years postsurgery were not statistically different from a matched group of total knee arthroplasty patients without bone grafts. There was no statistical difference in eventual motion or rating scores between those patients with a posterior cruciate-retaining and a posterior stabilized prosthesis. Four bone grafts demonstrated fragmentation and dissolution within the first year with implant subsidence. Needle biopsy performed one year postoperatively in nine knees in which the graft had not fragmented revealed osteocytes in the lacunae in only four grafts. In each of four further knees, there was a complete radiolucency between the graft and the tibial host bone. The overall success rate at five years was only 67%. This high failure rate has led the authors to reevaluate the use of prosthetic shims or wedges in large fragment defects but to continue to use bone grafting for smaller, circumscribed defects.

Arthritis, Rheumatoid↗
PubMed1988

Inhibition of epiphyseal cartilage collagenase by tetracyclines in low phosphate rickets in rats.

Drugs in the tetracycline family can inhibit mammalian tissue collagenase both in vitro and in vivo by a mechanism that is independent of antibiotic action. The epiphyseal cartilages of rachitic rats contain extremely high levels of collagenase (CGase), and we have used this model to study further the phenomenon of tetracycline inhibition of tissue CGase. Rickets was induced in rats by phosphate/vitamin D deficiency and parameters of gross bone morphology, bone chemistry, and serum chemistry were evaluated in both rachitic and nonrachitic animals with and without treatment with oral tetracyclines (TETs). Minocycline (or doxycycline) partially suppressed the appearance of many of the expected changes in the rachitic animals, including gross bone hardness, growth plate widening, long bone length, suppression of weight gain, and decreased bone ash content. The effects were dose dependent and were associated with marked suppression of the enhanced CGase activity. Examination of collagen breakdown products by SDS-PAGE documented that the rachitic enzyme behaved like other mammalian collagenases including in vitro inhibition with minocycline 10-20 micrograms/ml and with a nonantibiotic tetracycline. No evidence of TET osseous toxicity was noted, and, in fact, administration of TET to nonrachitic animals had a mildly favorable effect on growth and development. TET suppression of CGase can be demonstrated in a well defined model system and this form of pharmacologic enzyme inhibition can be a useful probe for delineating the role of the enzyme in connective tissue pathology.

Animals↗
PubMed1979

Intertrochanteric fractures of the hip in the elderly: a retrospective analysis of 236 cases.

A series of 236 patients over the age of 80 with intertrochanteric fractures were treated on a protocol established basis in an attempt to decrease postoperative morbidity and mortality. Rigid fixation with interfragmentary compression using the compression hip screw permitted us to begin early mobilization and immediate weight-bearing. Vigorous pulmonary tiolette, prophylactic antibiotics, and aspirin "anticoagulation" were used as adjuncts. Three month mortality was 7%. Overall, 76% of the patients who ambulated in any manner before their fracture walked again after surgery. Many, however, lost one grade level of walking postoperatively. Effective treatment for a patient with an intertrochanteric fracture, regardless of advanced age, is surgery and early mobilization.

Age Factors↗
PubMed1978

Unicompartmental tibiofemoral resurfacing arthroplasty.

Thirty-seven patients with unicompartmental osteoarthritis were treated by replacement arthroplasty using the Marmor modular prosthesis and each patient was followed for at least two years. Despite rigid preoperative criteria for the selection of cases, the over-all results were definitely inferior to those seen after either bicompartmental or tricompartmental replacement arthroplasty. Complications included recurrent pain and degeneration of the other compartment, often associated with abrasion of the remaining cartilaginous surfaces caused by polyethylene particles. There was also more settling of the tibial component in these patients than in patients treated by bicompartmental replacement arthroplasty. Because of these findings, we no longer use unicompartmental replacement of the medial side of the knee. The results after the three lateral compartment replacements, on the other hand, were good, and use of this procedure for post-traumatic arthritis is still under investigation.

Arthroplasty↗
PubMed1976

Modular total knee-replacement arthroplasty. A review of eighty-nine patients.

Fifty-eight osteoarthritic and thirty-one rheumatoid patients underwent modular total knee-replacement arthroplasty. The major indication for the operation was relief of pain. Contraindications to this resurfacing arthroplasty included varus-valgus instability of over 20 degrees, combined varus-valgus instability with flexion contracture of over 40 degrees, marked recurvatum, and predominant patellofemoral symptoms. In 59 per cent of the osteoarthritic and 58 per cent of the rheumatoid patients, complete relief of pain was evident when they were evaluated twenty-four months after surgery, while another 35 per cent of each group had only mild pain related to inclement weather. Their ability to walk long distances without support or limp was increased. Range of motion and ability to climb stairs were not significantly improved.

Aged↗
PubMed1975

A single stage osteotomy and epiphysiodesis for treatment of moderately displaced femoral capital epiphyses.

Epiphysiodesis and subtrochanteric osteotomy have long been recognized as valuable procedures in the treatment of the patient with a moderately or markedly displaced femoral capital epiphysis. Typically these have been performed individually or sequentially. The operation herein described combines the two in one single-stage procedure. Using a stainless steel Lorenzo Screw, the epiphyseal plate is transfixed and further capital displacement prevented. The subtrochanteric compensatory osteotomy is performed using simple visual clinical guidelines and is held rigidly immobilized with a variable angle sideplate affixed to the Lorenzo Screw. The firm fixation enables one to dispense with plaster immobilization and begin the patient on an early exercise program. Restoration of a more normal range of motion, especially regarding rotation internally, abduction, and flexion is easily obtained. Radiographic correction of varus and posterior tilting are thereby secured.

Adolescent↗