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Biomedical subjects

R Poss

Publications and source records attributed to R Poss.

14 recordsLinked to original sources
PubMed1992

A controlled evaluation of continuous passive motion in patients undergoing total knee arthroplasty.

OBJECTIVE: To evaluate the efficacy of continuous passive motion (CPM) in the postoperative management of patients undergoing total knee arthroplasty. DESIGN: A randomized controlled single-blind trial of CPM plus standardized rehabilitation vs standard rehabilitation alone. SETTING: A referral hospital for arthritis and musculoskeletal care. PATIENTS: Consecutive patients with end-stage osteoarthritis or rheumatoid arthritis undergoing primary total knee arthroplasty who had at least 90 degrees of passive knee flexion. One hundred fifty-four patients were eligible and 102 patients agreed to participate and were randomized. Ninety-three patients completed the study protocol. INTERVENTION: Continuous passive motion machines programmed for rate and specified arc of motion within 24 hours of surgery with range increased daily as tolerated with standardized rehabilitation program compared with standardized rehabilitation program alone. MAIN OUTCOME MEASURES: Primary outcomes were pain, active and passive knee range of motion, swelling (or circumference), quadriceps strength at postoperative day 7, as well as complications, length of stay, and active and passive range of motion and function at 6 weeks. RESULTS: Use of CPM increased active flexion and decreased swelling and the need for manipulations but did not significantly affect pain, active and passive extension, quadriceps strength, or length of hospital stay. At 6 weeks there were no differences between the two groups in either range of motion or function. In this series, use of CPM resulted in a net savings of $6764 over conventional rehabilitation in achieving these results. CONCLUSION: For the average patient undergoing total knee arthroplasty, CPM is more effective in improving range of motion, decreasing swelling, and reducing the need for manipulation than is conventional therapy and lowers cost.

Aged↗
PubMed1992

Osteotomies of the hip in the prevention and treatment of osteoarthritis.

Osteoarthritis of the hip is common in our society, even in the relatively young patient. Most of this osteoarthritis is mechanical in etiology and is secondary to residual deformity from developmental hip disease. This type of osteoarthritis can often be predicted and prevented if the causative excessive joint pressures are reduced in a timely fashion by corrective osteotomy. Realigning pelvic or intertrochanteric osteotomy of this preventive type is termed reconstructive; those osteotomies performed after osteoarthritis is established are termed salvage. Corrective osteotomy will be clinically successful only if the mechanical etiology for the potential or established osteoarthritis is clear and if the osteotomy succeeds in reducing the pathologically excessive joint loads. The clinical success of osteotomy also requires precise technical planning preoperatively and careful operative technique.

Adolescent↗
PubMed1992

Natural factors that affect the shape and strength of the aging human femur.

The human skeleton loses bone mass with increasing age. A wide variety of evidence suggests that the skeleton compensates for this decreased bone mass by increasing the second moment of area in the midshaft of long bones. Strain is the mechanical transducer of bone's adaptation to its mechanical environment. In the absence of strain, bone resorption occurs. Contemporary femoral prostheses are stiffer than the cortical bone that serves as their host and, therefore, induce stress shielding and bone resorption that augments the naturally occurring loss of bone mass with age. With the expectation that total hip replacement can endure 15-25 years, one must be aware that a new limit to its longevity may be the biologic failure of the host bone. Particulate debris, stress shielding, and the natural consequences of aging are conspiring to make the proximal femur a diminishing site. The design strategy and materials of fabrication of future total hip prostheses should seek to maximize the preservation of bone.

Adult↗
PubMed1990

Results of revision total knee arthroplasty performed for aseptic loosening.

One hundred thirty-seven revision total knee arthroplasties (TKA) performed in 117 patients with failed aseptic metal-to-plastic knees over ten years (1974-1984) were studied to determine the long-term clinical and roentgenographic results and were compared to primary TKA. The mean age was 65 years (range, 32-90 years). Fifty-three percent had rheumatoid arthritis, and 47% had osteoarthritis. The mean interval from initial to revision TKA (129 knees) was four years (range, three months to 11 years) and from the first to second revision (seven knees) was 2.4 years (range, seven months to 5.5 years). The most common reasons for failure were loosening (73%), patellar complications (13%), and instability (10%). The mean follow-up time was 5.2 years (range, two to 12 years). Function, instability, motion, and pain all improved after revision TKA, but these improvements were significantly less than those seen after primary TKA. One-third of the patients still ambulated with crutches, a walker, or not at all. While mean postoperative flexion was 100 degrees, 24% could not flex to 90 degrees. Most patients (90%) were malaligned at the time of failure and remained so after revision (78%). The increased incidence of radiolucent lines (tibial, 61%; femoral, 24%) was not related to increased failure. Complications were not increased over primary TKA. The failure rate was 5.8% at 5.2 years, or approximately 1% per year. A successful clinical result was defined as a knee with mild or no pain, mild or no instability, and flexion to at least 90 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Total knee arthroplasty with the kinematic prosthesis. Results after five to nine years: a follow-up note.

A review of the results of 192 kinematic total knee replacements five to nine years after the operation showed that the results were still satisfactory. At the time of the review, the ages of the patients ranged from twenty-two to eighty-seven years. About half of the patients had rheumatoid arthritis and the other half, osteoarthrosis. About 90 per cent of the results were rated good or excellent, and the average range of flexion was 109 degrees. Radiolucency was present around 40 per cent of the tibial components, 30 per cent of the femoral components, and 60 per cent of the patellar components, but the lines were thin and not progressive. The complications included loosening of the patellar components in five knees, one fracture of the tibial tray with loosening of the patellar component, one fracture of the patellar component, and one dislocation of the patellar component.

Adult↗
PubMed1979

Methylmethacrylate is a mutagen for Salmonella typhimurium.

The long-term effects of exposure to monomeric methylmethacrylate have yet to be established. We have measured the toxicity and mutagenicity of methylmethacrylate for Salmonella typhimurium. At levels of thirty-four millimolar, methylmethacrylate exhibited 28 per cent of the mutagenic activity of an equimolar dose of dimethylnitrosamine. Methylmethacrylate alone exhibited toxicity to the bacteria, but when the methylmethacrylate was incubated with a rat-liver enzyme metabolizing system, mutagenesis was induced. These findings suggest that an intermediate metabolite of methylmethacrylate is mutagenic to Salmonella typhimurium.

Adhesives↗
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↗
PubMedDate not supplied

Red cell transfusions in total knee and total hip replacement surgery.

To explore how red cell transfusions were used to support patients who underwent primary and revision hip and knee replacements classified within diagnosis-related group (DRG) 209 (major joint and limb reattachment procedures), we studied abstracted patient discharge records from 151 United States hospitals in 1986. A total of 9684 units of whole blood and/or separated red cells was used to support 6472 patients. The transfusion use varied by surgical procedure, with patient gender as an influencing factor. Large proportions of patients underwent surgery without requiring transfusion. Among transfused patients, the majority received 1 to 3 units of red cells; however, a minority of patients required multiple transfusions, thereby utilizing a disproportionate share of the blood resource. Comparison of transfusion practice within the seven most active hospitals revealed significant differences (p less than or equal to 0.01) in the percentage of patients actually transfused, but not in the mean number of units of red cell components transfused per transfused patient. Similar findings emerged from comparison of transfusion practice when all hospitals were segregated into five hospital classes on the basis of orthopedic surgical service activity. These effects were seen for both total knee and total hip replacement procedures. It can be concluded that the lack of clearly defined criteria for transfusion contributed to the variations observed.

Blood Transfusion↗
PubMedDate not supplied

Bilateral total hip and knee replacement in adults with rheumatoid arthritis: an evaluation of function.

Sixteen patients with advanced rheumatoid arthritis who underwent total joint replacements of both hips and both knees were followed for an average of 22.8 months postoperatively. Their functional status before and after surgery was assessed by use of a special rating system for function. Fourteen of the 16 patients demonstrated higher total function scores at follow-up. Improvement was most marked in walking endurance, need for walking aids, and ability to climb stairs. Factors which were believed to predispose to less functional improvement included older age at initial surgery, longer duration of disease, more severe upper extremity involvement, and more frequent medical illnesses. There were 8 patients in whom combined hip and knee flexion in one or both lower extremities did not exceed 190 degrees after surgery. When this deficiency was combined with severe involvement of the upper extremities, difficulty with activities such as climbing stairs and arising from a chair was more common. Therefore, the goal of surgical treatment is to provide combined hip and knee flexion in excess of 190 degrees in these patients. Total joint arthroplasty has increased the likelihood of functional improvement in patients with severe rheumatoid arthritis involving the hips and knees, and encouraged the surgeon to operate earlier in the course of the disease as well as on patients with severely deformed joints.

Adult↗