PubMed Health⌕ Search

Biomedical subjects

Arlen D Hanssen

Publications and source records attributed to Arlen D Hanssen.

At least 55 records · Page 3Linked to original sources
PubMed2004

The modular segmental kinematic rotating hinge for nonneoplastic limb salvage.

From January 1980 to July 1998, 25 patients (26 knees) were treated with an arthroplasty using a Modular Segmental Kinematic Rotating Hinge total knee prosthesis for nonneoplastic limb salvage. The indications included: nonunion of a periprosthetic femur fracture (11 knees), severe bone loss and ligamentous instability (eight knees), nonunion of a supracondylar femur fracture (four knees), acute periprosthetic fracture (one knee), fracture of a previous hinge (one knee), and prior resection arthroplasty (one knee). The average age of the patients was 72.3 years. Twenty-two arthroplasties were revisions. The average followup was 58.5 months. At the latest followup, knee extension averaged 2.4 degrees and flexion averaged 93.6 degrees. The Knee Society knee score improved from an average of 45.4 preoperatively to 75.5. Preoperatively, functional scores averaged 8.6 and improved to 25. Complications occurred in eight patients. The most common was deep infection (five patients). The use of the Modular Kinematic Rotating Hinge for nonneoplastic limb salvage represents a small proportion (0.14%) of all primary and revision knee arthroplasties done at our institution. The indications for the surgery are for a highly complex and small subset of patients. The patients in the current study gained significant improvement in overall range of motion, Knee Society knee scores, and functional scores when this prosthesis was used.

Aged↗
PubMed2004

Practical applications of antibiotic-loaded bone cement for treatment of infected joint replacements.

The use of antibiotic-loaded bone cement is an accepted treatment method for infected joint arthroplasties. It is helpful to separate the use of antibiotic-loaded bone cement as a method of prophylaxis as compared with the treatment of an established infection. A low dose of antibiotic-loaded bone cement (< or = 1 g of antibiotic per batch of cement) should be used for prophylaxis, and high-dose antibiotic-loaded bone cement (> 1 g antibiotic per batch of cement) is indicated for treatment. The only commercially available antibiotic-loaded bone cement products are low dose, with the use of tobramycin or gentamicin as an antibiotic selection. High-dose antibiotic-loaded bone cement requires hand mixing by the surgeon to facilitate the use of high dosages and choices of multiple antibiotics. Treatment of infected hip and knee arthroplasties with high-dose antibiotic-loaded bone cement is aided by the use of spacers of various shapes and sizes. These spacers, whether they are static or articulating (mobile), are meant to provide local delivery of antibiotics, stabilization of soft tissues, facilitation of an easier reimplantation, and improved clinical outcomes.

Anti-Bacterial Agents↗
PubMed2004

Systemic safety of high-dose antibiotic-loaded cement spacers after resection of an infected total knee arthroplasty.

The purpose of this study was to assess the systemic safety and potential adverse effects of using a high-dose antibiotic-impregnated cement spacer after resection arthroplasty of an infected total knee replacement. Between October 2000 and December 2002, 36 knees (34 patients) had a resection arthroplasty of an infected total knee prosthesis with placement of a high-dose antibiotic impregnated cement spacer. There were 24 men and 10 women with a mean age of 66.5 years (range, 48-84 years). All spacers placed contained an average of 3.4 batches of cement with an average total dose of 10.5 g of vancomycin (range, 3-16 g) and 12.5 g of gentamicin (range, 3.6-19.2 g). All patients were followed up post-operatively until reimplantation for evidence of renal failure. The preoperative creatinine ranged from 0.7 to 1.8 mg/dL. All patients were concomitantly treated with 6 weeks of intravenous organism-specific antibiotics. One patient with normal preoperative renal function (Cr 0.7 mg/dL) had a perioperative 1-day transient rise in serum creatinine (1.7 mg/dL) postoperatively that subsequently normalized. No patients showed any clinical evidence of acute renal insufficiency, failure, or other systemic side effects of the antibiotics. Treatment of patients with an infected total knee arthroplasty with high-dose vancomycin and gentamicin antibiotic spacers seems to be clinically safe.

Aged↗
PubMed2004

Gentamicin and vancomycin do not impair experimental fracture healing.

The purpose of this study was to determine whether gentamicin or vancomycin impair experimental fracture healing in rats. Forty-one male Wistar rats were divided into three groups, receiving either 1.5 mg/kg of gentamicin intramuscularly twice daily for 3 weeks (n = 15), 25 mg/kg of vancomycin intraperitoneally twice daily for 3 weeks (n = 14), or no treatment (n = 12), starting 7 days after production of closed, nondisplaced, bilateral femoral fractures. The mean 30 minute serum concentrations of gentamicin and vancomycin were 4.5 microg/mL and 35.1 microg/mL, respectively. Biomechanical and radiographic studies were used to evaluate fracture healing. Torsional strength testing of fracture callus exposed to gentamicin and vancomycin was similar (437 and 424 N-mm, respectively) to controls (334 N-mm). Radiographs showed similar healing in control animals (Goldberg score, 2.3) compared with rats treated with gentamicin and vancomycin (Goldberg score, 2.6 in both groups). Results of this study do not show impaired healing of experimental fractures after exposure to gentamicin or vancomycin (such as has been reported after exposure to quinolones).

Animals↗
PubMed2004

Bilateral total knee replacement using the same anesthetic is not justified by assessment of the risks.

The question of whether simultaneous bilateral knee replacement is associated with an increased risk of perioperative morbidity and mortality remains controversial. There are no true prospective randomized studies that address this question. There is general agreement that the risk is higher for older patients and for those with considerable medical comorbidities, particularly those with a history of cardiac disease. There is no general agreement on the appropriate threshold for age or comorbidities in order to minimize risk. Based on available retrospective data, there is evidence to suggest that there may be some patient selection bias favoring patients with simultaneous bilateral knee replacements; despite this bias, the perioperative risks are higher for these healthier patients. The highest risk for the patient having simultaneous bilateral knee replacement seems to be that of early postoperative mortality followed by the risk of a cardiac event. The risks of thromboembolic, gastrointestinal, and neurologic dysfunction also are increased. These patients also have a higher likelihood of requiring homologous blood transfusions and of requiring posthospitalization transfer to a rehabilitation center. Because of the absence of established patient selection criteria, thresholds for assessment of the increased risks, the patient having simultaneous bilateral replacement faces an increased risk of perioperative mortality and morbidity on a random basis. Patients should be aware of this information when deciding whether to proceed with simultaneous bilateral knee replacement.

Age Factors↗
PubMed2004

Mid-term to long-term followup of two-stage reimplantation for infected total knee arthroplasty.

Between January 1989 and December 1994, 94 patients (96 knees) had a two-stage reimplantation for treatment of an infected total knee arthroplasty. All patients were treated with an interval antibiotic-loaded static cement spacer and had antibiotic-loaded bone cement for prosthesis fixation at the time of reimplantation. The purpose of this study was to assess the long-term risk of reinfection and the mechanical durability of these reimplantation arthroplasties. Patients were followed up for a median of 7.2 years (range, 2.5-13.2 years). At final followup, 15 knees (16%) had required reoperation. Nine knees (9%) had component removal for reinfection and six knees (6%) were revised for aseptic loosening. The median time to reoperation for reinfection was 1 year (range, 0.1-9.8 years). The risk of recurrent infection was not correlated with the type of organism, patient demographics, or method of prosthesis fixation at reimplantation. The survivorship free of implant removal for any reason was 90% (confidence intervals, 83.9-96.4%) at 5 years and 77.3% (confidence intervals, 65.5-89.6%) at 10 years. The survivorship free of implant removal for reinfection was 93.5% (confidence intervals, 88.5-98.7%) at 5 years and 85% (confidence intervals, 73.8-96.3%) at 10 years. Survival free of revision for mechanical failure (aseptic loosening or radiographic loosening) was 96.2% (confidence intervals, 92-100%) at 5 years and 91% (confidence intervals, 80.8-98.3%) at 10 years. These results suggest that the high likelihood of early success after two-stage reimplantation of an infected TKA is well maintained throughout long-term followup, with a modest rate of late recurrent infection or mechanical implant failure.

Adult↗
PubMed2004

Modular porous metal augments for treatment of severe acetabular bone loss during revision hip arthroplasty.

Modular acetabular augments were implanted in 16 patients (16 hips) for support of an uncemented hemispheric acetabular component during revision acetabular reconstruction. Based on the classification of Paprosky, acetabular bone defects were classified as 2A in one hip, 2B in three hips, 2C in one hip, 3A in five hips, and 3B in six hips. Preoperatively, the prosthetic femoral head centers were located at a mean horizontal distance of 18.6 mm (range, -3-46 mm), and a mean vertical distance of 27.6 mm (range, -16-52 mm) from the approximate femoral head center. Postoperatively, the prosthetic femoral head centers were located at a mean horizontal distance of 10.4 mm (range, 1-25 mm), and a mean vertical distance of 7.4 mm (range, -15-25 mm). At final followup, no implant had evidence of migration or loosening. At early clinical followup, this modular acetabular augment system seems helpful in acetabular reconstructions that cannot be treated with an uncemented hemispheric cup that would have required other forms of treatment such as structural allografts, acetabular cages, bilobed acetabular components, or custom acetabular components. Longer term followup is required to determine whether there are untoward effects of using a modular acetabular reconstructive system.

Acetabulum↗
PubMed2004

Editorial comment.

Explore the source record for details and available documents.

Arthroplasty, Replacement, Hip↗
PubMed2004

icaA is not a useful diagnostic marker for prosthetic joint infection.

A collection of 99 staphylococcal isolates associated with prosthetic joint infection and 23 coagulase-negative staphylococci isolated from noninfected arthroplasty-associated specimens were screened in order to determine whether the presence of icaA could be used to distinguish between pathogens and nonpathogens. All Staphylococcus aureus prosthetic joint infection isolates (n = 55) were icaA positive. A total of 46% (20 out of 44) of coagulase-negative staphylococcal prosthetic joint infection isolates were icaA positive, and 30% (7 out of 23) of arthroplasty-associated non-prosthetic joint infection-associated coagulase-negative staphylococcal isolates were icaA positive (P = 0.23). Certain coagulase-negative Staphylococcus species appeared more likely to be isolated as either arthroplasty-associated non-prosthetic joint infection-associated isolates (e.g., Staphylococcus warneri and Staphylococcus hominis) or pathogens (e.g., Staphylococcus lugdunensis). The presence of icaA in a coagulase-negative staphylococcal isolate associated with an arthroplasty is not a useful diagnostic indicator of pathogenicity.

Arthroplasty↗
PubMed2004

Total knee arthroplasty following proximal tibial osteotomy: risk factors for failure.

BACKGROUND: The results of proximal tibial osteotomy are known to deteriorate over time, with the majority of patients eventually requiring total knee arthroplasty. The outcome of total knee arthroplasty in patients who have had a proximal tibial osteotomy, compared with that of routine primary total knee arthroplasty, remains controversial. The purpose of the present study was to evaluate the long-term clinical and radiographic outcome of total knee arthroplasty in patients who had undergone a previous proximal tibial osteotomy and to identify the risk factors that may result in an inferior outcome. METHODS: Between 1980 and 1990, 166 cemented condylar total knee prostheses were implanted in 118 patients who had had a previous proximal tibial osteotomy for the treatment of osteoarthritis. The study group included seventy-seven men and forty-one women who had a mean age of 69.1 years at the time of knee arthroplasty. The average interval between the osteotomy and the total knee arthroplasty was 8.6 years. The average duration of clinical follow-up was 15.1 years, and the average duration of radiographic follow-up was 9.2 years. RESULTS: The mean Knee Society pain score improved from 34.5 to 82.9 points, and the mean function score improved from 44.6 to 88.1 points. There was also a substantial improvement in the mean arc of motion. Thirteen knees (8%) were revised at a mean of 5.9 years. At the time of the final follow-up, progressive complete radiolucent lines indicating a loose prosthesis were present around seventeen tibial components and seven femoral components. CONCLUSIONS: There was a very high rate of radiographic evidence of loosening. Male gender, increased weight, young age at the time of total knee arthroplasty, coronal laxity, and preoperative limb malalignment were identified as risk factors for early failure. Despite these findings, total knee arthroplasty can provide reliable and durable pain relief and improvement in function for patients who have had a previous proximal tibial osteotomy. LEVEL OF EVIDENCE: Prognostic study. Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.

Age Factors↗
PubMed2004

Revision of failed patellar components.

In the majority of revision knee replacements, the existing patellar component is well fixed and it is possible to retain the existing patellar component when specific criteria are met. If the patellar component is loose, malpositioned, or damaged, it should be revised. The decision regarding whether to implant another prosthesis or to perform an alternative procedure is dependent on an assessment of remaining patellar bone stock. Patellae with severe bone deficiency, which preclude adequate fixation of another patellar implant, occur in approximately 10% of revision knee replacements. Specific techniques include patellar resection arthroplasty, the gull-wing osteotomy, structural bone grafting of the patella, morcellized bone grafting of the patella, or use of a porous metal augmentation baseplate. Whether the patellar revision being performed is an isolated procedure or is part of revision arthroplasty, optimal positioning of the femoral and tibial component is important for proper patellar kinematics.

Arthroplasty, Replacement, Knee↗
PubMed2004

Rotating platform knees did not improve patellar tracking: a prospective, randomized study of 240 primary total knee arthroplasties.

Renewed interest in mobile-bearing total knee replacement designs has been generated by the concept of self alignment and the suggestion that those designs can accommodate small mismatches in the rotational position of the tibial and femoral components. Self alignment might improve patellar tracking, decrease the prevalence of lateral retinacular release and postoperative patellar tilt or subluxation, improve knee flexion, and improve patellofemoral function during daily activities such as stair climbing. This prospective randomized study of 240 patients used a single posterior-stabilized femoral component and included three groups of 80 patients: an all-polyethylene group, a modular metal-backed group, and a rotating platform tibia group. The prevalence of lateral retinacular release was 3.8% in each group. The prevalence of patellar tilt was 5% (all-polyethylene group), 7% (modular metal-backed group), and 11% (rotating platform group). Preoperative motion was not significantly different and both the 3-month flexion (112 degrees , 110 degrees , and 108 degrees ) and 1-year flexion (116 degrees , 117 degrees , and 115 degrees ) were not significantly different among the all-polyethylene, modular metal-backed, and rotating platform groups, respectively. Preoperative stair climbing scores were not significantly different and both the 3-month (38, 41, and 35 points) and 1-year (44, 46, and 42 points) scores were not significantly different. In this prospective randomized study, the rotating platform knee design did not decrease the prevalence of lateral retinacular release or patellar tilt or subluxation and did not increase knee flexion or improve stair climbing ability at 3 months or at 1 year postoperatively when compared with a posterior-stabilized, fixed-bearing knee.

Adult↗
PubMed2003

Cemented long-stem revision total knee arthroplasty.

From 1981 to 1989, 38 cemented, posterior, stabilized, revision, total knee arthroplasties (TKAs) were performed at the authors' institution using the stemmed kinematic stabilizer prosthesis of a single design. The mean clinical follow-up after the index procedure was 10.1 years. The Knee Society pain score averaged 17 points before revision and improved to 51 points at last follow-up, and the function score averaged 48 points before revision and improved to 57 at last follow-up. Ten-year component survival free of revision or removal for any reason was 96.7%; 11-year component survival free of revision for aseptic loosening was 95.7%. Cemented stem fixation in revision TKA provides good clinical results with durable fixation at an average of 10 years' follow-up.

Adult↗
PubMed2003

Cementation of an acetabular liner into a well-fixed acetabular shell during revision total hip arthroplasty.

Cementing a polyethylene liner into a well-fixed acetabular shell during revision hip arthroplasty may be appropriate in select patients. The purpose of this study was to review our early results with this technique. Sixteen patients with >2-year follow-up or who had any complications at <2 years from surgery were identified. Indications for this technique included: failure of the previous locking mechanism, significant polyethylene wear, malposition of the well-fixed metal shell, and previous removal of the liner with a retained acetabular shell. One acetabular shell has been revised at 13 months for multiple dislocations. Hip scores improved an average of 24.2 points. Radiographs revealed no polyethylene dissociation or acetabular loosening. Complications occurred in 7 patients. Initial results appear successful at providing secure fixation, while preventing the bone loss that might occur with removal of a well-fixed component.

Aged↗
PubMed2003

Total knee arthroplasty in post-traumatic arthrosis of the knee.

Total knee arthroplasty is an effective method of treatment for the majority of patients with a prior distal femoral or tibial plateau fracture and end-stage arthritis. There is a higher complication rate and overall poorer outcome when compared with routine primary total knee arthroplasty. In patients for whom the goals of optimal limb and implant alignment are achieved, the results are comparable with routine primary knee arthroplasty. Patients with suboptimal component positioning or residual deformity have a poorer outcome. The technical challenges encountered can require skills, implant systems, and methods usually reserved for complex revision arthroplasty.

Arthritis↗