Showing papers by "Arlen D. Hanssen published in 1996"

The Effect of Superior Placement of the Acetabular Component on the Rate of Loosening after Total Hip Arthroplasty. Long-Term Results in Patients Who Have Crowe Type-II Congenital Dysplasia of the Hip*

Abstract: A method for measurement of the true acetabular region and the approximate femoral head center as well as a classification consisting of four zones for assessment of the acetabular position of the acetabular cup were used to analyze the results of primary total hip arthroplasty with cement in 117 patients (145 hips). All patients had Crowe type-II congenital dysplasia of the hip. The mean age at the time of the arthroplasty was fifty-one years (range, fifteen to seventy-six years), and the mean duration of follow-up was fourteen years (range, two to twenty-two years). The initial position of the acetabular cup outside of the true acetabular region and outside of zone 1 (inferior and medial) was associated with an increase in the rates of loosening (p < 0.05) and revision (p < 0.04) of the femoral components. Cups that initially were more than fifteen millimeters superior to the approximate femoral head center, without lateral displacement, were associated with an increased rate of loosening (p < 0.001) and of revision (p < 0.04) of the femoral components as well as with an increased rate of loosening (p < 0.002) and of revision (p < 0.01) of the acetabular components. These findings suggest that superior positioning of the acetabular component, even without lateral displacement, leads to increased rates of loosening of the femoral and acetabular components. An attempt should be made to position the acetabular component in or near the true acetabular region.

Prevention of deep periprosthetic joint infection.

Abstract: Although the prevalence of postoperative deep wound infection after total joint arthroplasty has decreased over the past few decades, it remains a feared consequence for both surgeons and patients107. Moynihan stated that “every operation in surgery is an experiment in bacteriology.”80 This statement provides remarkable insight into the seemingly variable and unpredictable nature of infection. Often, the specific mechanism and timing of bacterial delivery in a given wound is unknown, and it is usually extremely difficult to prove the exact cause of the infection in an individual situation. Despite improved outcomes of treatment for established deep periprosthetic infection, prevention remains a meaningful objective. The estimated cost of treatment67 of an infection at the site of a total hip or total knee arthroplasty exceeds $50,000. A thorough appreciation of and respect for the innumerable factors that may contribute to an infection is essential in the development of an over-all approach to prevention. The concept of an interdependent relationship among the triad of bacteria, host, and wound is helpful when considering prevention Fig. 1. Infection depends on the number and virulence of the bacteria introduced into a wound, the host's ability to eliminate these bacteria, and the status or viability of the wound environment. Within this triad, multiple variables can contribute to the deposition of bacteria into the wound, many conditions may impair the patient's ability to eliminate bacteria, and numerous vagaries of the wound milieu can facilitate the infectious process (Table I). Every variable may be influenced by the other variables within the triad. For example, the effect of a foreign body on the absolute number of bacteria required to facilitate the infectious process is well known29. Venn diagram demonstrating the dependent nature of bacteria, host factors, and wound environment on the development of …

Total knee arthroplasty in a previously ankylosed or arthrodesed knee.

Abstract: Few reports address the reconstructive challenge of total knee arthroplasty after a surgically fused or ankylosed knee. The long term results and complications of a large series of patients who have had their ankylosed or arthrodesed knee converted to a total knee replacement were evaluated. Thirty-seven knees (35 patients, 28 female and 7 male) without any motion in the knee were retrospectively reviewed in a multicenter study after total knee arthroplasty. The mean age was 53 years, and the average length of followup was 90 months. The results at followup showed an average 7 degrees lack of extension and 62 degrees flexion. Complications included 24% short term complications and 35% major complications with a 14% infection rate. The total complication rate was 57%. A satisfactory outcome (no pain and an unlimited ambulation distance) was obtained in only 10 patients (29%). Patients with a satisfactory outcome had an average age of 45, and postoperative knee flexion of 87 degrees, significantly different from those with an unsatisfactory outcome. There was no relationship between results and the angle at which the knee was ankylosed preoperatively. This analysis indicates that although success in reconstructing a previously ankylosed or arthrodesed knee is possible, the lack of consistent adequate motion and the complication rate may suggest that the surgeon reconsider the risks and benefits of this difficult procedure.