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Arlen D Hanssen

Publications and source records attributed to Arlen D Hanssen.

At least 37 records · Page 2Linked to original sources
PubMed2005

The diagnosis of prosthetic joint infection: current techniques and emerging technologies.

It is important to diagnose prosthetic joint infection accurately because the medical and surgical treatment of prosthetic joint infection differs from that of other causes of prosthetic joint failure. Recognition of the presence or absence of infection at or before the time of surgery is important in directing the appropriate surgical approach. Recovery and susceptibility testing of the infecting organism are essential to the selection of appropriate anti-infective therapy.

Bacteria↗
PubMed2005

Local antibiotic delivery vehicles in the treatment of musculoskeletal infection.

The primary benefit achieved with local antibiotic delivery vehicles is the ability to obtain extremely high levels of local antibiotics without increasing systemic toxicity. Antibiotic-loaded bone cement represents the current standard as an antibiotic delivery vehicle in orthopaedic surgery. Biodegradable alternatives to antibiotic-loaded bone cement also are being used clinically and there are many new products in the active stages of development. These alternatives can be categorized as bone graft, bone graft substitutes or extenders, natural polymers (protein-based products), and synthetic polymers. Composite biomaterials that simultaneously provide the functions of variable antibiotic delivery patterns and also contribute to the process of bone regeneration represent the most ideal class of local antibiotic delivery vehicles. High concentrations of certain antibiotics have been shown to affect the process of normal bone regeneration adversely in a dose dependent response. Considerable investigation still is required to determine the proper use of locally administered antibiotics to negotiate the balance between eradicating infection without excessively inhibiting the processes of bone regeneration.

Anti-Bacterial Agents↗
PubMed2005

Editorial comment.

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Congresses as Topic↗
PubMed2005

High rate of aminoglycoside resistance among staphylococci causing prosthetic joint infection.

Gentamicin and tobramycin are two aminoglycosides commonly impregnated into polymethylmethacrylate for treatment and prevention of prosthetic joint infection. Susceptibilities of staphylococci to aminoglycosides are not reported routinely in the United States. The gentamicin and tobramycin minimum inhibitory value of 93 staphylococci from patients with PJI were determined. Forty-one and 66% of the isolates were resistant to gentamicin and tobramycin, respectively. Methicillin-resistant Staphylococcus aureus isolates were more likely to be resistant to gentamicin or tobramycin than were their methicillin susceptible counterparts. The findings suggest that consideration should be given to the further study of agents other than aminoglycosides for incorporation into polymethylmethacrylate for the treatment and prevention of prosthetic joint infection.

Anti-Bacterial Agents↗
PubMed2005

Two-incision THA had modest outcomes and some substantial complications.

UNLABELLED: Proponents of two-incision total hip arthroplasty suggest the technique is minimally invasive and promotes rapid rehabilitation with a low prevalence of complications. We applied the two-incision total hip arthroplasty technique to a consecutive group of unselected patients with primary degenerative arthritis to determine the technical difficulty of the operation as measured by the operative time compared with a standard posterior approach, the safety of the operation as measured by the prevalence of complications compared with a standard posterior approach, and the early functional outcome measured by the time to return to activities of daily living as compared with a previous study of the two-incision technique in selected younger patients. The 80 patients included 45 women and 35 men with a mean age of 70.5 years. The patients treated with a two-incision method had longer operative times and substantially more complications than did the patients treated with a standard posterior approach. The early functional outcomes in this group of unselected patients were modest when compared with the previous results in selected younger patients. Patient and surgeon enthusiasm for the potential benefits of the two-incision total hip arthroplasty should be tempered by the modest early outcomes and the substantial prevalence of complications found in this group of typical patients having total hip arthroplasty. LEVEL OF EVIDENCE: Prognostic study, Level III (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Adult↗
PubMed2005

Prosthetic joint infection.

Infection is the second most common cause of prosthetic joint failure. Signs and symptoms associated with prosthetic joint infection may develop weeks or even years following arthroplasty. While some patients with prosthetic joint infection present with findings consistent with acute septic arthritis, many present with pain alone. Morbidity and cost associated with repeat surgery, prolonged medical treatment and joint immobilization render importance to the accurate and timely diagnosis, and appropriate treatment of prosthetic joint infection. No consensus exists, however, in terms of the most cost-effective diagnostic methods or the ideal medical and/or surgical interventions. This review describes diagnostic tests and available treatment for prosthetic joint infection and gives a practical approach to this challenging clinical entity.

Anti-Bacterial Agents↗
PubMed2005

Quadriceps tendon rupture after total knee arthroplasty. Prevalence, complications, and outcomes.

BACKGROUND: There is relatively little information about quadriceps tendon tears after total knee arthroplasty. The purpose of this study was to determine the prevalence of this condition and the outcomes of patients who had a tear of the quadriceps tendon after a total knee arthroplasty. METHODS: From a cohort of 23,800 primary total knee arthroplasties, we identified twenty-four patients who had a rupture of the quadriceps tendon postoperatively. Ten additional patients had the total knee arthroplasty done elsewhere and were referred for care after sustaining a tear of the quadriceps tendon. Thus, the study group consisted of thirty-four patients, and all had at least two years of follow-up. Eleven patients had a complete tear, and twenty-three had a partial tear. RESULTS: The prevalence of a quadriceps tendon tear after total knee arthroplasty was 0.1% (twenty-four of 23,800). Seven patients with a partial tear were treated nonoperatively, and all had a satisfactory outcome. One patient with a complete tear was treated nonoperatively and had an unsatisfactory result. Of the ten patients treated operatively after a complete tear, four subsequently had rerupture of the repaired tendon and four had a satisfactory outcome. Of the sixteen patients with a partial tear treated operatively, only one had rerupture and twelve had a satisfactory outcome. Complications occurred in eleven of the twenty-six patients managed operatively. CONCLUSIONS: The prevalence of complications was high, and the outcomes were poor for seven of the eleven patients who had a complete quadriceps tendon tear after total knee arthroplasty. Patients who sustained a partial tear and were treated nonoperatively had no complications and had uniformly good outcomes.

Adult↗
PubMed2005

Early postoperative transverse pelvic fracture: a new complication related to revision arthroplasty with an uncemented cup.

BACKGROUND: Uncemented hemispherical cups are commonly used to revise failed acetabular total hip components, even in the presence of marked acetabular bone loss. The purpose of the present study was to report a new complication of acetabular component revision with an uncemented hemispherical cup. METHODS: We retrospectively reviewed the records of seven patients (seven hips) in whom an early postoperative transverse acetabular fracture had developed following the implantation of an uncemented trabecular metal cup for the revision of a failed acetabular component. All patients were female. The average age was 63.6 years. The reason for acetabular revision was aseptic loosening of the original cup in five patients and reimplantation after a previous resection arthroplasty in the remaining two. The average cup size used for revision was 58 mm. In two hips, additional modular acetabular metal augments were used to restore the acetabular rim. RESULTS: The average postoperative time to diagnosis of a transverse acetabular fracture was eight months. Five of the seven patients presented with a marked acute increase in pain and a new displaced transverse acetabular fracture (pelvic discontinuity) that was visible on plain radiographs. Two patients were asymptomatic but had a nondisplaced transverse acetabular fracture. In all seven patients, the trabecular metal socket appeared radiographically to be well fixed to part of the pelvis. The five patients with a displaced fracture were managed with additional surgery to stabilize the fracture. CONCLUSIONS: To our knowledge, early postoperative transverse pelvic fractures following revision of the acetabular component have not been reported previously. The most likely causes of this complication are further weakening of the remaining pelvic bone stock as a result of the reaming required to obtain a secure fit of a large-diameter hemispherical socket and the cyclic stresses on the weakened bone with resumption of walking. It is unlikely that the fractures occurred intraoperatively because in each case the socket remained well fixed to one of the pelvic fragments.

Adult↗
PubMed2004

Synovial fluid leukocyte count and differential for the diagnosis of prosthetic knee infection.

PURPOSE: Criteria for the interpretation of synovial fluid are well established for native joint disorders but lacking for the evaluation of prosthetic joint failure. Our aim was to define cutoff values for synovial fluid leukocyte count and neutrophil percentage for differentiating aseptic failure and prosthetic joint infection. METHODS: We performed a prospective study of 133 patients in whom synovial fluid specimens were collected before total knee arthroplasty revision between January 1998 and December 2003. Patients with underlying inflammatory joint disease were excluded. RESULTS: Aseptic failure was diagnosed in 99 patients and prosthetic joint infection was diagnosed in 34 patients. The synovial fluid leukocyte count was significantly higher in patients with prosthetic joint infection (median, 18.9 x 10(3)/microL; range, 0.3 to 178 x 10(3)/microL) than in those with aseptic failure (median, 0.3 x 10(3)/microL; range, 0.1 to 16 x 10(3)/microL; P <0.0001); the neutrophil percentage was also significantly higher in patients with prosthetic joint infection (median [range], 92% [55% to 100%] vs. 7% [0% to 79%], P <0.0001). A leukocyte count of >1.7 x 10(3)/microL had a sensitivity of 94% and a specificity of 88% for diagnosing prosthetic joint infection; a differential of >65% neutrophils had a sensitivity of 97% and a specificity of 98%. Staphylococcus aureus was the only pathogen associated with leukocyte counts >100 x 10(3)/microL. CONCLUSION: A synovial fluid leukocyte differential of >65% neutrophils (or a leukocyte count of >1.7 x 10(3)/microL) is a sensitive and specific test for the diagnosis of prosthetic knee infection in patients without underlying inflammatory joint disease.

Adult↗
PubMed2004

Prophylactic use of antibiotic bone cement: an emerging standard--in opposition.

Antibiotic-loaded bone cement (ABLC) is an effective delivery method of local antibiotics. ABLC for treatment should be high dose (>3.6 g per 40 g cement) for beads or spacers and 1 to 2 g antibiotic per 40 g cement for prosthesis fixation. Multiple antibiotics are required for treatment, with antibiotics being individualized according to culture susceptibilities. This approach requires hand mixing because there are no commercial high-dose products. ABLC should be low dose (< or =1 g per 40 g cement) for prophylaxis purposes. Concerns with toxicity and cement mechanical properties are inconsequential with low-dose ABLC. Available clinical evidence supports low-dose ABLC for prophylaxis in revisions and high-risk primary joints, but concerns of emerging drug-resistant organisms probably outweigh routine use of low-dose ABLC in all uncomplicated primary arthroplasties.

Anti-Bacterial Agents↗
PubMed2004

Release of daptomycin from polymethylmethacrylate beads in a continuous flow chamber.

Because daptomycin is active against Gram-positive cocci, it may be useful in the treatment and prevention of bone and joint infections when incorporated into polymethylmethacrylate (PMMA). The release kinetics of daptomycin from PMMA were studied in a continuous flow chamber designed to simulate in vivo conditions. Three-millimeter beads containing 2.5%, 7.5%, and 15.0% daptomycin (weight daptomycin per weight PMMA) were individually placed in a chamber with 1 mL Krebs Ringer buffer flowing at 1 mL/hour. The majority of daptomycin was released in the first 24 hours. The mean peak concentrations were 13.4, 62.3, and 146.7 microg/mL; the mean AUC0-infinity were 30, 272, and 1204 h x microg/mL; and the mean percentages of daptomycin released were 6%, 18%, and 42% for the beads containing 2.5%, 7.5%, and 15.0% daptomycin, respectively. Daptomycin is released from PMMA in a continuous flow chamber at a rate similar to that previously determined by our laboratory for vancomycin.

Anti-Bacterial Agents↗
PubMed2004

Treatment of the infected hip replacement.

Selection of the suitable treatment method for an infected hip arthroplasty requires careful assessment of patient-related variables and expected treatment goals. The basic treatment options include antibiotic suppression, open debridement, resection arthroplasty, arthrodesis, reimplantation of another prosthesis, and amputation. Successful treatment of infection requires complete debridement of all infected and foreign material and appropriate antimicrobial therapy. When possible, the preferred treatment approach is insertion of another prosthesis with a delayed reconstructive treatment technique. Patients now are presenting with an increasing incidence of resistant organisms and severe bone loss, which increases the difficulty of treatment.

Anti-Bacterial Agents↗