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Biomedical subjects

A D Hanssen

Publications and source records attributed to A D Hanssen.

At least 19 recordsLinked to original sources
PubMed2006

Outcome of prosthetic joint infections treated with debridement and retention of components.

BACKGROUND: Debridement and retention of the prosthesis represents an attractive surgical modality for treatment of prosthetic joint infection, but risk factors for treatment failure require clarification. METHODS: We conducted a retrospective cohort analysis of all patients with a prosthetic joint infection who were treated with debridement and retention of the prosthesis at the Mayo Clinic (Rochester, Minnesota) between 1995 and 1999. RESULTS: Debridement and retention of the prosthesis was the initial treatment modality for 99 episodes of prosthetic joint infection that occurred in 91 patients who presented to the Mayo Clinic during 1995-1999. A total of 32% and 23% of all episodes were due to Staphylococcus aureus and coagulase-negative staphylococci, respectively. The median duration of intravenous antimicrobial therapy was 28 days (range, 1-90 days). Oral antimicrobial suppression was used in 89% of the episodes, for a median duration of 541 days (range, 5-2673 days). Treatment failure occurred in 53 episodes during a median follow-up period of 700 days (range, 1-2779 days). The 2-year survival rate free of treatment failure was 60% (95% confidence interval [CI], 50%-71%). Variables associated with an increased risk of treatment failure in multivariable analysis included the presence of a sinus tract (hazard ratio, 2.84; 95% CI, 1.48-5.44; P = .002) and a duration of symptoms prior to debridement of > or = 8 days (hazard ratio, 1.77; 95% CI, 1.02-3.07; P = .04). CONCLUSIONS: Debridement and retention of the prosthesis is a common surgical modality at our institution to treat prosthetic joint infection. Risk factors independently associated with treatment failure include the presence of a sinus tract and duration of symptoms prior to debridement of > or = 8 days.

Adult↗
PubMed2005

Prosthetic joint infection diagnosed postoperatively by intraoperative culture.

The purpose of this study was to assess the outcome of prosthetic joint infection initially diagnosed by multiple positive intraoperative cultures after revision arthroplasty and treated by strategies that include less than 6 weeks of intravenous antimicrobial therapy. Between January 1995 and December 1999, 16 of 509 (3%) episodes of prosthetic joint infection in 16 patients initially were diagnosed by positive intraoperative cultures after revision arthroplasty. Patients were followed up for a median of 1057 days (range, 731-1969 days). The median age of the patients was 65 years, and 65% of patients had revision total hip arthroplasty. Coagulase-negative staphylococci and Propionibacterium spp were the main pathogens identified. Intravenous antimicrobial therapy was used in 81% of patients and chronic oral suppression was used in 56% of patients. Three patients received no antimicrobial therapy. The median duration of intravenous antimicrobial therapy was 28 days (range, 2-42 days). The 5-year survival free of treatment failure for the 16 episodes was 89%. These results suggest a favorable outcome of prosthetic joint infections because of low virulence pathogens initially diagnosed as positive intraoperative cultures after revision arthroplasty with a variety of medical treatment strategies, including strategies that contain less than 6 weeks intravenous antimicrobial therapy.

Administration, Oral↗
PubMed2003

Outcome of penicillin-susceptible streptococcal prosthetic joint infection treated with debridement and retention of the prosthesis.

Debridement with retention of the prosthesis was the initial treatment modality for 19 cases of penicillin-susceptible streptococcal prosthetic joint infection that occurred in 18 patients who presented to the Mayo Clinic (Rochester, Minnesota) during 1969-1998. All of the cases of prosthetic joint infection occurred >30 days after implantation of the prosthesis, which was well fixed at the time of debridement. The median duration of symptoms before debridement was 4 days (range, 1-10 days). Treatment failure (defined as relapse of infection with the original microorganism) occurred in 2 cases (10.5%) during a median follow-up period of 3.9 years (range, 0.3-21.7 years). The 1-year cumulative risk of relapse was 11% (95% confidence interval, 0%-26%). Relapse of prosthetic joint infection due to penicillin-susceptible streptococci after debridement and retention of the prosthesis is uncommon. For patients who present with a well-fixed prosthesis and a short duration of symptoms, debridement with retention appears to be an effective treatment modality.

Adolescent↗
PubMed2001

Infection after shoulder arthroplasty.

Between 1972 and 1994, 2279 patients underwent primary shoulder arthroplasty (2512 shoulders) and 194 patients underwent revision shoulder arthroplasty (222 shoulders) at the authors' institution. Of these, 18 patients with primary shoulder arthroplasties (19 shoulders) and seven patients with revision shoulder arthroplasties (seven shoulders) were diagnosed with deep periprosthetic infection. Additionally, during this period, seven patients (seven shoulders) with primary shoulder arthroplasties and one patient (one shoulder) with a previously revised shoulder arthroplasty were referred to the authors' institution for treatment of deep periprosthetic infection. Two patients (two shoulders) were excluded because of incomplete medical records and with component removal performed elsewhere. The average time from arthroplasty to the diagnosis of infection was 3.5 years (range, 0-14.8 years). The patients were divided into four groups on the basis of treatment. Group I comprised 20 patients (21 shoulders) who underwent resection arthroplasty. Six of the 21 shoulders had additional episodes of infection. Group II comprised six patients (six shoulders) who underwent debridement and prosthetic retention. Three of the six shoulders failed this treatment with subsequent reinfection and underwent a resection arthroplasty. Group III comprised two patients (two shoulders) who had removal of the prosthesis, debridement, and immediate reimplantation. One patient underwent resection arthroplasty 9 months after direct exchange because of reinfection. Group IV comprised three patients (three shoulders) who had removal of the prosthesis, debridement, and delayed reimplantation. Reinfection has not occurred in any of these patients. At final followup, patients with a prosthesis in situ had better pain relief and shoulder function than patients treated with resection arthroplasty. Delayed reimplantation may offer the best hope for pain relief, eradication of infection, and maintenance of shoulder function.

Adult↗
PubMed2001

Use of recombinant human erythropoietin in two-stage total knee arthroplasty for infection.

A multicenter prospective study was conducted to determine whether epoetin alfa could be used to lower transfusion requirements after two-stage exchange arthroplasty for infection. Forty-one consecutive patients undergoing successful two-stage exchange arthroplasty for an infected total knee arthroplasty were enrolled in a prospective study. Epoetin alfa (40,000 units) was administered subcutaneously after prosthesis resection and antibiotic spacer placement. Although there was no difference in the hemoglobin levels before resection arthroplasty or on postoperative Day 3 between the study group and the control group, hemoglobin levels before reimplantation were higher in the patients who received epoetin alfa (12.4 mg/dL; range, 9.3-15.1 mg/dL) compared with the control group (11.3 mg/dL; range, 8.1-14.4 mg/dL). Average increase in hemoglobin level in the interval between stages was higher in the treatment group (3.2 mg/dL; range, -0.7-6.8 mg/dL) than the control group (1.7 mg/dL; range, -1.9-6 mg/dL). The transfusion rate decreased from 83% of patients in the control group to 34% in the study group during reimplantation. In addition, overall incidence of transfusion for either stage improved from 89% in the control group to 44% in the patients treated with epoetin alfa. Perioperative epoetin alfa statistically increased the hemoglobin levels and decreased transfusion rates for patients undergoing two-stage revision for infected total knee arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMed2001

Total knee arthroplasty in patients with isolated patellofemoral arthritis.

The current study evaluated the results of total knee arthroplasty for the treatment of isolated patellofemoral degenerative arthritis. Between 1980 and 1997, 31 total knee arthroplasties were done in 24 patients with advanced, isolated patellofemoral arthritis. The average followup was 5.2 years (range, 2-12 years). There was a significant improvement in the mean preoperative Knee Society pain and function scores. Twenty-one knees required a lateral retinacular release and three knees required additional formal proximal realignment at the time of the total knee arthroplasty. There were three reoperations in this series including, manipulation for poor motion in one patient; revision of a loose patellar component in one patient; and extensor mechanism realignment in the third patient. At midterm followup, total knee arthroplasty proved to be reliable and durable in alleviating pain and improving function in this group of patients with isolated, advanced patellofemoral arthritis. Surgeons should be made aware, however, that resurfacing of the patella and balancing the extensor mechanism for patients with isolated patellofemoral arthritis can be demanding technically as evidenced by the high rate of asymmetrically resurfaced patellas, the high rate of lateral retinacular release, and formal realignment procedures.

Aged↗
PubMed2001

The kinematic rotating hinge prosthesis for complex knee arthroplasty.

Fifty-eight patients (69 knees) treated with the Kinematic Rotating Hinged knee prosthesis for complex primary and salvage revision total knee arthroplasty were followed up for an average of 75.2 months (range, 24-199 months). The indications for use of the Kinematic Rotating Hinged knee prosthesis included severe bone loss combined with ligamentous instability (30 knees), nonunion of a periprosthetic fracture (10 knees), an acute periprosthetic fracture (nine knees), severe collateral ligamentous instability (five knees), reimplantation for infection (six knees), nonunion of a supracondylar femoral fracture (four knees), congenital dislocation of the knee (three knees), and treatment of a severely comminuted distal femur (two knees). At the time of surgery, the average patient age was 72 years (range, 46-92 years). Preoperatively, knee extension averaged 4.94 degrees (range, 0 degrees-40 degrees) and flexion averaged 81 degrees (range, 15 degrees-125 degrees). At final followup, knee extension averaged 1.25 degrees (range, -5 degrees-25 degrees) and flexion averaged 94.2 degrees (range, 5 degrees-125 degrees). The preoperative Knee Society Knee score averaged 40.3 points (range, 2-93 points) and improved to 77 points (range, 33-99 points) at final followup. Complications were numerous: 23 (32%) patients experienced at least one complication and 12 (17%) patients had two or more complications. Deep periprosthetic infection was the most common complication (14.5%), followed by patellar complications (13%), and prosthetic component breakage (10%). During the period of this study, there were 15,798 primary and 2673 revision total knee arthroplasties done at the authors' institution. The patients receiving a Kinematic Rotating Hinged knee prosthesis represent a highly complex and small subset (0.37%) of the overall population having knee arthroplasty. Although the use of the Kinematic Rotating Hinged knee prosthesis for these limited indications has been useful for the authors, the incidence of complications and the poor outcome of these complications is disconcerting. Hinged total knee arthroplasty should be reserved for the final salvage option of the treatment options available when doing complex primary and salvage revision knee arthroplasties.

Aged↗
PubMed2001

Bone-grafting for severe patellar bone loss during revision knee arthroplasty.

BACKGROUND: Severe patellar bone loss may preclude adequate fixation of another patellar prosthesis as a part of revision knee replacement. The purpose of this study was to describe the surgical technique and early clinical results of an alternative to the conventional treatment options of either patellectomy or retention of the remaining patellar osseous shell. The goals of this procedure are to restore patellar bone stock and potentially to improve the functional outcome. METHODS: Severe patellar bone loss had left a "patellar shell" that precluded insertion of another patellar implant in nine of 100 consecutive knees undergoing revision total knee arthroplasty. Rather than performing a patellectomy or simply retaining the patellar osseous shell in these nine knees (eight patients), I performed a surgical procedure in which a tissue flap was secured to the patellar rim to contain cancellous bone graft inserted into the patellar bone defect. Final follow-up was at a mean of 36.7 months (range, twenty-four to fifty-five months) after the patellar bone-grafting procedure. RESULTS: The mean preoperative Knee Society scores for function and pain were 39 points (range, 18 to 82 points) and 40 points (range, 20 to 80 points), respectively. At the time of final follow-up, the Knee Society function and pain scores had improved significantly, to a mean function score of 91 points (range, 80 to 98 points) and a mean pain score of 84 points (range, 65 to 100 points) (p<0.05). The point of greatest patellar thickness measured intraoperatively ranged from 7 to 9 mm. Patellar thickness on immediate postoperative Merchant radiographs averaged 22 mm (range, 20 to 25 mm) whereas, at the time of final follow-up, patellar thickness averaged 19.7 mm (range, 17 to 22.5 mm). CONCLUSIONS: In contrast with other treatment alternatives, this surgical procedure imparts the potential for restoring patellar bone stock and may improve functional outcome by facilitating patellar tracking and improving quadriceps leverage. On the basis of satisfactory short-term to mid-term clinical results, this technique of patellar bone-grafting appears to be an important addition to the armamentarium of surgeons performing revision knee arthroplasties.

Aged↗
PubMed2001

Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: a case-control study.

OBJECTIVE: To identify and assess the impact of postoperative complications in patients with unrecognized or known obstructive sleep apnea syndrome (OSAS) undergoing hip replacement or knee replacement compared with control patients undergoing similar operations. Although OSAS is a risk factor for perioperative morbidity, data quantifying the magnitude of the problem in patients undergoing non-upper airway operations are limited. PATIENTS AND METHODS: This retrospective, case-control study from a single academic medical institution included patients diagnosed as having OSAS between January 1995 and December 1998 and undergoing hip or knee replacement within 3 years before or anytime after their OSAS diagnosis. Patients with OSAS were subcategorized as having the diagnosis either before or after the surgery and also, regardless of time of diagnosis, by whether they were using continuous positive airway pressure (CPAP) prior to hospitalization. Matched controls were patients without OSAS undergoing the same operation. Interventions were defined specifically as administration of a particular treatment in the context of each complication, eg, supplemental oxygen, implementation of additional monitoring such as oximetry for hypoxemia, or transfer to the intensive care unit (ICU) for cardiac ischemia concerns. Postoperative complications were assessed for all patients in the different categories and included respiratory events such as hypoxemia, acute hypercapnia, and episodes of delirium. Serious complications were noted separately, including unplanned ICU days, reintubations, and cardiac events. The length of hospital stay was also tabulated. RESULTS: There were 101 patients with the diagnosis of OSAS in this study and 101 matched controls. Thirty-six patients had their joint replacement before OSAS was diagnosed, and 65 had surgery after OSAS was diagnosed. Of the latter 65 patients, only 33 were using CPAP at home preoperatively. Complications were noted in 39 patients (39%) in the OSAS group and 18 patients (18%) in the control group (P=.001). Serious complications occurred in 24 patients (24%) in the OSAS group compared with 9 patients (9%) in the control group (P=.004). Hospital stay was significantly longer for the OSAS patients at a mean +/- SD of 6.8 +/- 2.8 days compared with 5.1 +/- 4.1 days for the control patients (P<.007). CONCLUSION: Adverse postoperative outcomes occurred at a higher rate in patients with a diagnosis of OSAS undergoing hip or knee replacement compared with a group of matched control patients.

Adult↗
PubMed2001

Varus tibial joint line obliquity: a potential cause of femoral component malrotation.

In 60 consecutive total knee arthroplasties done in 52 patients with primary osteoarthritis and varus or neutral tibiofemoral alignment, the posterior condylar angle was calculated intraoperatively and averaged 3.98 degrees (range, 0 degrees-9 degrees). Eighteen knees had a posterior condylar angle value less than 3 degrees whereas 27 knees had a posterior condylar angle value of 5 degrees or greater. Final rotational alignment of the femoral component was set parallel to the transepicondylar axis. Only one of these 60 knees required a lateral retinacular release for proper patellar tracking during the knee arthroplasty. When compared with three previously defined angles measured on the radiographs taken preoperatively, only the tibial plateau-tibial shaft angle values were correlated significantly with the value of the posterior condylar angle. As the tibial varus joint line obliquity increased, there was a distinct tendency for the transepicondylar axis to be rotated more externally relative to the posterior condylar axis. This variance suggests that the use of the posterior condylar axis as a rotational reference is inappropriate in many knees with arthritis with varus or neutral tibiofemoral alignment. In particular, varus tibial joint line obliquity of more than 4 degrees increases the likelihood of femoral component malrotation when the posterior femoral condyles are used to reference femoral component rotation.

Adult↗
PubMed2000

Treatment of periprosthetic tibial fractures.

Periprosthetic fractures of the tibia are less commonly encountered and have received less attention than periprosthetic fractures of the patella and distal femur. In contrast with distal femoral fractures, tibial fractures frequently are encountered with loose implants and treatment often requires simultaneous revision knee surgery to address the loose prosthesis, the fracture, and any associated bone deficiencies. In some instances, fractures associated with well-fixed and satisfactorily positioned knee components may be treated by traditional methods of operative or nonoperative fracture management. A classification system, which accounts for the anatomic location of the fracture, the status of prosthesis fixation, and timing of the fracture is helpful in description of the various fracture patterns and direction of the appropriate treatment approach.

Arthroplasty, Replacement, Knee↗
PubMed2000

Assessment of patient selection criteria for treatment of the infected hip arthroplasty.

In a group of 37 infected hip arthroplasties (36 patients) treated consecutively between January 1997 and October 1999, the feasibility of published patient selection criteria for direct exchange arthroplasty was tested. These criteria include the requirement of a healthy patient with good soft tissues, minimal femoral bone loss, and an organism identified preoperatively as an antibiotic sensitive gram-positive organism. After assignment of the selection criteria, only four patients (four hips) (11%) were deemed potential candidates for a direct exchange procedure. Infected arthroplasties excluded from a primary exchange included 14 patients (15 hips) with gram-negative or methicillin-resistant gram-positive organisms obtained from preoperative joint aspirations, 10 patients (10 hips) with moderate or severe femoral bone loss, four patients (four hips) who required a proximal femoral osteotomy for component removal, two patients (two hips) with poor health status, and two patients (two hips) with poor soft tissues. Because of the increasing emergence of antibiotic-resistant bacteria and an increased prevalence of revision arthroplasties with associated bone loss, the feasibility of published selection criteria for direct exchange are limited. A philosophy of delayed reconstruction for the treatment of the infected hip arthroplasty seems most appropriate in the current era of patient treatment.

Acetabulum↗
PubMed2000

Ciprofloxacin inhibition of experimental fracture healing.

BACKGROUND: Fluoroquinolones, such as ciprofloxacin, have an adverse effect on growing cartilage and endochondral ossification in children. This study was carried out to determine whether ciprofloxacin also has an adverse effect on the healing of experimental fractures. METHODS: Sixty male 300-gram Wistar rats were divided equally into three groups, which received ciprofloxacin, cefazolin, or no treatment for three weeks, beginning seven days after production of a closed, nondisplaced, bilateral femoral fracture. The serum concentrations of the ciprofloxacin and the cefazolin were 2.4 and 146 micrograms per milliliter, respectively. Radiographic, histological, and biomechanical studies were used to evaluate fracture-healing. RESULTS: Radiographs revealed significantly more advanced healing of the control fractures compared with the fractures in the ciprofloxacin-treated group (average stage, 2.1 compared with 1.5, p = 0.01). The cefazolin-treated group was not different from the controls with respect to radiographic healing (average stage, 1.8 compared with 2.1, p = 0.18). Torsional strength-testing of fracture callus exposed to ciprofloxacin revealed a 16 percent decrease in strength compared with the controls (284 compared with 338 newton-millimeters, p = 0.04) and a 49 percent decrease in stiffness (twenty compared with thirty-nine newton-millimeters per degree, p = 0.001). The biomechanical strength in the cefazolin-treated group was not different from that of the controls. Fracture calluses in the animals treated with ciprofloxacin showed abnormalities in cartilage morphology and endochondral bone formation and a significant decrease in the number of chondrocytes compared with the controls (0.77 x 10(4) compared with 1.3 x 10(4) cells per square millimeter, p = 0.004). CONCLUSIONS: These data suggest that experimental fractures exposed to therapeutic concentrations of ciprofloxacin in serum demonstrate diminished healing during the early stages of fracture repair. The administration of ciprofloxacin during early fracture repair may compromise the clinical course of fracture-healing.

Animals↗
PubMed2000

Reduction of vancomycin use in orthopedic patients with a history of antibiotic allergy.

OBJECTIVE: To reduce prophylactic vancomycin use in patients with a history of penicillin or cephalosporin allergy undergoing elective orthopedic surgery by using a targeted allergy consultation and penicillin allergy skin testing. PATIENTS AND METHODS: The participants in this practice improvement study were patients with a history of penicillin or cephalosporin allergy who were scheduled for elective orthopedic surgery and referred by orthopedic surgeons for allergy consultation and penicillin allergy skin testing between September 22, 1998, and April 15, 1999. The primary outcome measure was the percentage of participants who received prophylactic cefazolin during the study period compared with historical controls. RESULTS: Of the 60 study patients, 59 received a penicillin allergy skin test, 58 underwent orthopedic surgery, and 55 received antibiotic prophylaxis. Fifty-five patients had a history of allergy to penicillin, a cephalosporin, or both, and 5 had a history of nonspecific antibiotic allergy. Of the 59 patients, 55 (93%) had negative penicillin allergy skin test results. Fifty-four (90%) of the 60 patients were given clearance by the allergist to receive cefazolin. Of the 55 study patients who received antibiotic prophylaxis, 6 (11%) received vancomycin compared with 38 (30%) of 127 historical controls (P < or = .05). None of the study patients had an immediate reaction to cefazolin or to vancomycin. CONCLUSION: Prophylactic vancomycin use in patients with a history of penicillin or cephalosporin allergy undergoing elective orthopedic surgery can be reduced by a targeted allergy consultation and penicillin allergy skin testing.

Adolescent↗