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Biomedical subjects

R Poss

Publications and source records attributed to R Poss.

At least 37 records · Page 2Linked to original sources
PubMed1995

The impact of modularity in total hip arthroplasty.

Use of modularity in total hip arthroplasty has been of benefit in terms of allowing inventory reduction while providing surgeon versatility and thus optimal joint reconstruction. As with any advancement, the improvements gained must be weighed against their cost. The authors sought to examine the effects that modularity may have on the results of total hip arthroplasty in terms of bone loss, durability of fixation, time to failure, and incidence of revision. Using data from their total joint registry, the authors examined their experiences with total hip arthroplasties done during the past 25 years. They sought to compare the results of total hip arthroplasties in patients who differed chiefly by the number of modular junctions present in their hip prostheses. With each incremental increase in modularity, an earlier appearance of radiolucencies, an earlier occurrence of aseptic loosening, and an increased incidence of osteolysis in the absence of loosening was found. The authors conclude that suboptimal design rather than the concept of modularity best explains these results. The presence of suboptimal design in a total hip arthroplasty may cause polyethylene to be stressed beyond its performance limits.

Hip Prosthesis↗
PubMed1994

A clinical prediction rule for delirium after elective noncardiac surgery.

OBJECTIVE: To develop and validate a clinical prediction rule for postoperative delirium using data available to clinicians preoperatively. DESIGN: Prospective cohort study. SETTING: General surgery, orthopedic surgery, and gynecology services at Brigham and Women's Hospital, Boston, Mass. PATIENTS: Consenting patients older than 50 years admitted for major elective noncardiac surgery between November 1, 1990, and March 15, 1992 (N = 1341). MEASUREMENTS: All patients underwent preoperative evaluations, including a medical history, physical examination, laboratory tests, and assessments of physical and cognitive function using the Specific Activity Scale and the Telephone Interview for Cognitive Status. Postoperative delirium was diagnosed using the Confusion Assessment Method or using data from the medical record and the hospital's nursing intensity index. Patients were followed up for the duration of hospitalization to determine major complication rates, length of stay, and discharge disposition. RESULTS: Postoperative delirium occurred in 117 (9%) of the 1341 patients studied. Independent correlates included age 70 years or older; self-reported alcohol abuse; poor cognitive status; poor functional status; markedly abnormal preoperative serum sodium, potassium, or glucose level; noncardiac thoracic surgery; and aortic aneurysm surgery. Using these seven preoperative factors, a simple predictive rule was developed. In an independent population, the rule stratified patients into groups with low (2%), medium (8%, 13%), and high (50%) rates of postoperative delirium. Patients who developed delirium had higher rates of major complications, longer lengths of stay, and higher rates of discharge to long-term care or rehabilitative facilities. CONCLUSIONS: Using data available preoperatively, clinicians can stratify patients into risk groups for the development of delirium. Since delirium is associated with a variety of adverse outcomes, patients with substantial risk for this complication could be candidates for interventions to reduce the incidence of postoperative delirium and potentially improve overall surgical outcomes.

Aged↗
PubMed1994

Blood product utilization in hip and knee arthroplasty: effect of gender and autologous blood on transfusion practice.

Analysis of total blood product support for a 1-year cohort of patients undergoing hip or knee total joint arthroplasty showed significant differences in transfusion therapy between patients who predeposited autologous blood and those who did not. In primary joint arthroplasty, 51% of nonpredepositing patients undergoing hip replacement and 28% of nonpredepositing patients undergoing knee replacement required red cell transfusions. In revision procedures, 58-61% were transfused. Predepositors requiring only autologous blood received less blood per patient than nonpredepositors; however, 73-87% of primary and 86-88% of revision arthroplasty patients were transfused. Predepositors receiving supplemental allogeneic blood used a volume of red cells comparable to nonpredepositing patients, which was significantly greater than the red cell requirement of predepositors using only autologous blood. Moreover, regardless of predeposit status, the extent of red cell replacement differed between men and women. Male patients presented with significantly higher hematocrits and were less likely to be transfused than females undergoing the same procedure. However, once the transfusion-decision was made, the average amount of red cells given for each procedure did not show gender-related variation. Despite differences in admission and lowest observed hematocrits, all patients were discharged with hematocrits in the same range, suggesting that men were replaced with relatively less blood than women. These differences in transfusion practice relating to gender and predeposit status could not be associated with identifiable changes in clinical outcome which might provide rationale for the observed differences in practice.

Blood Transfusion↗
PubMed1994

Catastrophic failure of the polyethylene liner of uncemented acetabular components.

Ten cases are described of catastrophic failure of the polyethylene liner of three different designs of uncemented acetabular component. Failure occurred as a result of either 'wearthrough' to the metal backing, liner fracture or a combination of both, at a mean of 4.6 years after implantation (2 to 7.6). At revision there was metallosis in all hips and osteolysis of the femur or the pelvis in six. Catastrophic failure was seen only in cups with a minimum polyethylene thickness of less than 5 mm.

Acetabulum↗
PubMed1993

Influence of age on measurement of health status in patients undergoing elective surgery.

PURPOSE: To assess the influence of age on the relationships between global measures of health and specific health dimensions. DESIGN: Cross-sectional cohort study. SETTING: University tertiary care hospital. PATIENTS: Patients older than 50 years admitted for major elective non-cardiac surgery. MEASUREMENTS: Consenting patients underwent preoperative evaluations including a medical history, physical examination, and administration of health status assessment instruments. Global health status was measured with the Medical Outcomes Study Short Form (SF-36) and with a 0 to 100 verbal measure of global health. Specific health dimensions (physical function, role function, social function, mental health, energy and fatigue, and pain) were measured using the SF-36. Subjects also completed a second validated measure of physical functioning, the Specific Activity Scale (SAS). RESULTS: Although patients aged > 70 years (n = 276) had poorer role function, energy, and fatigue scores and poorer physical function on both the SF-36 and SAS than younger patients (n = 469) (P < 0.05), they had similar overall health perception. In the entire population, global health status as measured with the SF-36 health perception scale had the greatest correlation with the energy and fatigue scale (r = .45), correlated moderately with mental health (r = .35), social function (r = .32), and physical function (r = .33), and correlated less well with the surgically remediable dimension of pain (r = .23). However, correlations of global health perception with pain and global health perception with role functioning were significantly (P < or = 0.05) lower in older patients when compared with subjects 70 years or younger (r = .13 vs .28 and r = .19 vs .33, respectively). CONCLUSION: Despite poorer role function, poorer energy and fatigue scores, and poorer physical function, elderly persons have similar global health perception when compared with younger individuals. These data indicate that global health perception may be determined by different factors in the elderly or that the elderly have fundamentally different expectations of what their global health status should be. Our findings emphasize the importance of multidimensional scales when evaluating quality of life because, particularly in the elderly, the use of global measures alone may not reflect critically important dimension-specific impairments in health.

Activities of Daily Living↗
PubMed1993

Capitellocondylar total elbow replacement in rheumatoid arthritis. Long-term results.

We evaluated the long-term results of 202 capitellocondylar total elbow replacements that had been performed, from July 1974 through June 1987, in 172 patients. The duration of follow-up averaged sixty-nine months (range, twenty-four to 178 months). At the most recent follow-up examination, use of a 100-point rating score demonstrated an improvement from an average preoperative score of 26 points (range, 2 to 50 points) to an average postoperative score of 91 points (range, 45 to 100 points). The most improvement occurred in the categories of relief of pain, functional status, and range of motion in all planes except extension. The improvements in these categories and in the roentgenographic appearance that were seen in the early postoperative period did not deteriorate with time. The average preoperative arc of motion at the elbow ranged from -37 degrees of extension to 118 degrees of flexion. The average postoperative arc of motion at the elbow ranged from -30 degrees of extension to 135 degrees of flexion. Supination improved from 45 degrees preoperatively to 64 degrees postoperatively; pronation improved from 56 degrees preoperatively to 72 degrees postoperatively. The roentgenograms showed a radiolucent line adjacent to eight humeral and nineteen ulnar components; most of the lines were incomplete and one millimeter wide or less. Revision of the prosthesis was necessary in three elbows (1.5 per cent) because of loosening without infection, and in three additional elbows because of dislocation of the prosthesis. Complications included deep infection in three elbows (1.5 per cent); problems related to the wound in fifteen (7 per cent); permanent, partial sensory ulnar-nerve palsy in five (2.5 per cent); permanent, partial motor ulnar-nerve palsy in one (0.5 per cent); and dislocation in seven (3.5 per cent).

Adult↗
PubMed1993

Long-term complications after total knee arthroplasty with or without resurfacing of the patella.

The long-term complications related to the patella were retrospectively evaluated for 891 knees (684 patients) that had had a total arthroplasty, with or without resurfacing of the patella, with use of an unconstrained, condylar, posterior-cruciate-preserving prosthesis. The study population comprised two groups of patients who were similar in size, age, sex distribution, and diagnosis. One group (396 knees [303 patients]) had had a total knee arthroplasty with patellar resurfacing and the other group (495 knees [381 patients]) had had the same procedure without resurfacing. The average duration of follow-up was six and one-half years (range, two to fifteen years). The decision to resurface the patella was based on subjective inspection of the articular surface and on assessment of patellar tracking at the time of the operation. Resurfacing was performed if there was loss of cartilage, exposed bone, gross surface irregularities, or tracking abnormalities. Complications occurred an average of three years (range, immediately postoperatively to nine years) after the operation in the group that had had resurfacing and an average of four years (range, immediately post-operatively to ten years) postoperatively in the group that had not had resurfacing. In the group that had had resurfacing, there was loosening of the patellar component in five knees, patellar subluxation in four knees, fracture of the patella in three knees, rupture of the patellar tendon in three knees, and chronic peripatellar pain in one knee. In the group that had not had resurfacing, the complications included patellar subluxation in five knees, rupture of the patellar tendon in two knees, and chronic peripatellar pain in fifty-one knees.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Total Joint Replacement: Optimizing Patient Expectations.

Rehabilitation of the patient who has undergone total hip or knee replacement embraces many facets of care, including prevention of complications, patient education, and a program of gradual resumption of normal functions. This program may be divided into three phases. In the perioperative phase, elimination of factors that contribute to morbidity will facilitate resumption of physical activities. In the interim phase (the first year following surgery), the patient's desire to return to full activities must be tempered by the goal of preserving for the longest possible time the mechanical-biologic construct of the joint replacement. Although a final functional result is usually achieved in the first 2 to 3 years following surgery, the patient must be followed up indefinitely. During this third phase of long-term assessment, the question of whether total joint arthroplasty was a success must be answered by the surgeon, by the patient, and by society.

Journal Article↗
PubMed1993

Two- to four-year experience with cemented, press-fit, and porous coated applications of the profile total hip system.

The clinical outcome and radiographic results of 90 cemented profile stems, 59 press-fit profile stems and 20 porous-coated profile stems implanted between October, 1987 and December, 1989 were analyzed. All total hip replacements were performed by the same group of surgeons. All used a cementless porous ingrowth acetabular component, and all femoral components were of the same geometrical design. Clinical results were evaluated using the Hip Society/SICOT/AAOS consensus format and were recorded prospectively preoperatively and at 6 months, 1 year, 2 years, 3 years and 4 years postoperatively. Radiographs were evaluated for component migration, subsidence, and cortical and cancellous biologic response as well as zonal analysis of radiolucent lines, using the Muller THR template. The functional results were similar for all three groups with no significant differences at 2 years postoperatively with respect to pain with activity, limp, or support used. However, patient satisfaction tended to be higher for cemented stems than for press-fit or porous-coated stems. Radiographic analysis showed press-fit stems to have a higher incidence (29.5%) of femoral component subsidence (mean 5.7 mm). None of the porous-coated stems subsided. Press-fit and porous-coated stems also demonstrated a higher rate of cortical hypertrophy at mid- and distal stem levels in comparison to cemented components. Press-fit application of the femoral component gives satisfactory clinical results, and the addition of proximal porous coating may confer additional advantages to the technique. Cemented stems enjoy the highest level of patient satisfaction and the most predictable objective clinical results.

Adult↗
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↗