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Biomedical subjects

J O Anglen

Publications and source records attributed to J O Anglen.

At least 19 recordsLinked to original sources
PubMed2003

Heterotopic ossification prophylaxis with indomethacin increases the risk of long-bone nonunion.

Indomethacin is commonly administered for the prophylaxis of heterotopic ossification (HO) after the surgical treatment of acetabular fractures. Non-steroidal anti-inflammatory drugs such as indomethacin, have been associated with delayed healing of fractures and mechanically weaker callus. Our aim was to determine if patients with an acetabular fracture, who received indomethacin for prophylaxis against HO, were at risk of delayed healing or nonunion of any associated fractures of long bones. We reviewed 282 patients who had had open reduction and internal fixation of an acetabular fracture. Patients at risk of HO were randomised to receive either radiation therapy (XRT) or indomethacin. Of these patients, 112 had sustained at least one concomitant fracture of a long bone; 36 needed no prophylaxis, 38 received focal radiation and 38 received indomethacin. Fifteen patients developed 16 nonunions. When comparing patients who received indomethacin with those who did not, a significant difference was noted in the rate of nonunion (26% v 7%; p = 0.004). Patients with concurrent fractures of the acetabulum and long bones who receive indomethacin have a significantly greater risk of nonunion of the fractures of the long bones when compared with those who receive XRT or no prophylaxis.

Acetabulum↗
PubMed2002

The use of detergent irrigation for musculoskeletal wounds.

The primary purpose of irrigation is to remove bacterial contaminants from the wound. Surfactants do that by disrupting the bonds of the organism to the surface. The use of this wound care strategy was studied in a series of investigations spanning several years. In vitro experiments revealed that surfactant irrigation was superior to saline or antibiotic solutions for removal of adherent bacteria from metallic surfaces, from bone, and from bovine muscle. An in vivo model of the complex orthopedic wound was developed. The superiority of surfactant irrigation over saline or antibiotic solution was demonstrated in animal wounds containing metal, bone injury, and soft tissue damage. Specificity of different surfactant irrigations for various bacterial species was demonstrated. A sequential surfactant irrigation protocol was developed and shown effective in the polymicrobial wound with established infection.

Animals↗
PubMed2001

Elution characteristics of tobramycin from polycaprolactone in a rabbit model.

This study investigated the elution characteristics of tobramycin from polycaprolactone, a bioabsorbable polymer, in a rabbit model. Sixty rabbits were divided into two groups. Group 1 had polycaprolactone rods impregnated with 6% tobramycin surgically implanted into the proximal femoral intramedullary canal. Group 2 received polymethylmethacrylate rods of like size, shape, and antibiotic concentration. Serum and urine samples were obtained, and tobramycin levels were determined via fluorescent immunosorbent assay. Rabbits were sacrificed as long as 56 days after surgery. Local bone tobramycin concentration was determined using the agar diffusion method. Polycaprolactone delivered a significantly higher peak bone concentration of tobramycin (22.4 microg/mL) than did polymethylmethacrylate (13.59 microg/mL). Polycaprolactone also had a more gradual decrease in local tobramycin concentration than did polymethylmethacrylate. Neither polycaprolactone nor polymethylmethacrylate yielded consistently detectable (> 0.1 microg/mL) serum tobramycin levels. Urine concentrations mirrored those seen in bone, with polycaprolactone achieving significantly higher tobramycin concentrations than did polymethylmethacrylate. Polycaprolactone had superior elution characteristics compared with polymethylmethacrylate in this lapine model, suggesting that polycaprolactone might be a promising local antibiotic delivery vehicle for the treatment of osteomyelitis.

Animals↗
PubMed2001

In vitro elution of tobramycin from bioabsorbable polycaprolactone beads.

OBJECTIVES: To compare the in vitro elution characteristics of tobramycin impregnated beads made of polycaprolactone (PCL) and polymethylmethacrylate (PMMA). DESIGN: Six-millimeter PCL and PMMA beads with 6% tobramycin were formed and placed in phosphate-buffered saline or newborn calf serum and incubated at room temperature or 37 degrees C. Aliquots were taken at intervals for eight weeks. Tobramycin levels were determined by fluorescent assay and antibacterial efficacy was assessed by measuring the zones of inhibition against Staphylococcus aureus and Pseudomonas aeruginosa on agar diffusion plates. RESULTS: Tobramycin elution rates at room temperature were similar up to three weeks. At three weeks, elution rates from PCL beads were twice those from PMMA beads, and at eight weeks, elution from PCL was quadruple that from PMMA. At 37 degrees C, tobramycin elution rates from PCL were eight times greater than those from PMMA by eight weeks. Total tobramycin eluted from PCL beads was 38.9% and 20% in PMMA beads. All samples showed bacteriostatic activity against S. aureus and P. aeruginosa at eight weeks. CONCLUSIONS: These in vitro results show that PCL has superior antibiotic elution characteristics compared with PMMA, and this may translate into a more effective antibiotic delivery vehicle. In addition, PCL is a bioabsorbable polymer, which may decrease the need for a second surgical procedure to remove retained beads.

Analysis of Variance↗
PubMed2001

Synergy between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds.

BACKGROUND: We observed an interaction in animals inoculated concomitantly with Staphylococcus aureus and Pseudomonas aeruginosa during a study of the efficacy of surfactants for disinfection of orthopaedic wounds. This led us to investigate whether synergy could be demonstrated between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds. METHODS: A wire was implanted into the spinous process of a lumbar vertebra of Sprague-Dawley rats through a dorsal incision. Animals were divided into two groups: group one was inoculated with either Staphylococcus aureus or Pseudomonas aeruginosa, and group two received a polymicrobial inoculation with both test organisms in varying concentrations. After inoculation, the wounds were irrigated and closed. On postoperative day 14, all animals were killed and specimens from the wounds were cultured. The number of colony-forming units (CFU) of Staphylococcus aureus or Pseudomonas aeruginosa needed to cause infection in 50% of the animals (ID50) was determined with use of the Reed-Muench method. The infection rate associated with each inoculum combination was calculated, and the two groups were compared. RESULTS: The ID50 was 2.8 x 10(4) CFU for Staphylococcus aureus and 4.8 x 10(5) CFU for Pseudomonas aeruginosa. The combination of 10(3) CFU of Staphylococcus aureus with low concentrations (10(2), 10(3), or 10(4) CFU) of Pseudomonas aeruginosa yielded infection rates that were higher than those found with either organism alone at the same concentrations. The combination of 10(3) CFU of Staphylococcus aureus and 10(3) CFU of Pseudomonas aeruginosa yielded a 75% infection rate, which was significantly higher (p = 0.004) than that associated with 10(3) CFU of either organism alone. As the Pseudomonas aeruginosa concentration was increased (to 10(5), 10(6), and 10(7) CFU), this trend reversed, and the infection rate decreased to 33% (p = 0.004). Low concentrations of Pseudomonas aeruginosa (0 to 10(5) CFU) combined with 10(6) CFU of Staphylococcus aureus yielded infection rates ranging from 83% to 100%. At the higher concentrations of Pseudomonas aeruginosa (10(6) and 10(7) CFU), however, the infection rate again decreased, to 33% (p = 0.005). Only Staphylococcus aureus was isolated from the cultures of the specimens from the animals that had received a polymicrobial inoculum. CONCLUSIONS: Synergy between Staphylococcus aureus and Pseudomonas aeruginosa was demonstrated when low levels of each organism were present in the wound. As the Pseudomonas aeruginosa concentration was increased, the infection rates fell well below what would be anticipated, suggesting that low concentrations of Pseudomonas aeruginosa enhance the ability of Staphylococcus aureus to cause infection in this orthopaedic wound model. At the same time, the presence of Staphylococcus aureus in the ratios tested decreased the rate of infection by Pseudomonas aeruginosa. CLINICAL RELEVANCE: Staphylococcus aureus is a pathogen commonly seen in orthopaedic patients. The pathogenicity of Staphylococcus aureus was shown to be increased in the presence of anaerobic bacteria. This study is the first one that we are aware of that demonstrated synergy between Staphylococcus aureus and Pseudomonas aeruginosa, at low concentrations, in a wound model while at the same time showing that Staphylococcus aureus lowers the rate of Pseudomonas aeruginosa infection.

Animals↗
PubMed2001

Indomethacin compared with localized irradiation for the prevention of heterotopic ossification following surgical treatment of acetabular fractures.

BACKGROUND: There is controversy surrounding the relative effectiveness of local irradiation and oral indomethacin for prophylaxis against heterotopic ossification following surgical treatment of acetabular fractures. The purpose of this study was to compare the efficacy of these two commonly used methods in a prospective, randomized trial. METHODS: From July 1992 to June 1999, 166 patients in whom a fracture of the acetabulum was treated surgically through a posterior, extensile, or combination approach were randomized to receive either indomethacin or radiation therapy postoperatively. Seventy-eight patients received 800 cGy of local radiation therapy within seventy-two hours after surgery, and seventy-two patients received a six-week course of indomethacin (25 mg three times a day) beginning within twenty-four hours after surgery. Sixteen additional patients were randomized but did not receive treatment with either prophylactic regimen. At an average of fourteen months, the extent of heterotopic ossification was assessed on plain radiographs with use of the classification of Brooker et al. The grade of ossification was correlated with hip motion. RESULTS: There was no significant difference between treatment groups with regard to patient age, gender, Glasgow Coma Scale, operative time, estimated operative blood loss, duration of follow-up, or presence of closed head injury. The Injury Severity Score appeared to be the only covariate that was significantly different between the groups (p = 0.019). Grade-III or IV ossification developed in eight (11%) of the patients in the indomethacin group and three (4%) in the radiation therapy group. The difference was not significant (p = 0.22; 95% confidence interval, -1.1%, +15.7%). No complications related to the prophylaxis were noted in either group. Heterotopic ossification developed in all sixteen patients who did not receive prophylaxis, with six demonstrating grade-III or IV changes. The overall prevalence of grade-III or IV heterotopic ossification was 7% (eleven of 150) in the treated groups and 38% (six of sixteen) in the untreated group. We did not find any association between the prevalence of heterotopic ossification and fracture type (p = 0.296) or posterior hip dislocation (p = 0.306). Grade-I, II, and III heterotopic ossification did not decrease the range of motion of the hip except in flexion. CONCLUSIONS: Both local radiation therapy and indomethacin were found to provide effective prophylaxis against heterotopic ossification following surgical treatment of acetabular fractures through a posterior or extensile approach. We detected no significant difference in efficacy between the two prophylactic regimens.

Acetabulum↗
PubMed1999

Early outcome of hybrid external fixation for fracture of the distal tibia.

OBJECTIVE: To evaluate the early results of treatment when using hybrid external fixation for fractures of the tibial plafond. DESIGN: Retrospective review of patients treated according to protocol. Patients treated with the hybrid fixator were compared with patients treated with open reduction and internal fixation. SETTING: Orthopaedic trauma service of a Level I trauma center, with a single surgeon directing care. PATIENTS/PARTICIPANTS: All patients with fractures of the distal tibia during a five-year period (n = 63) were treated according to protocol, with specific criteria determining method of treatment. Eleven patients were lost to follow-up, and three additional patients were not reviewed for other reasons. Follow-up period averaged twenty months. INTERVENTION: Fracture stabilization was accomplished with the use of a hybrid external fixator (n = 34) or with internal fixation (n = 27), as determined by patient or fracture criteria. Two patients did not receive planned treatment. MAIN OUTCOME MEASUREMENTS: Range of motion, clinical ankle score, and incidence of complications. RESULTS: Patients treated with hybrid fixation had lower clinical scores, slower return to function, a higher rate of complications, more nonunions and malunions, and more infections. CONCLUSIONS: Due to differences in patient populations, the superiority of either treatment method is uncertain; however, hybrid fixation did not seem to solve the problems inherent in severe pilon fractures. The sanguine results reported in the literature did not hold true in this group.

Adolescent↗
PubMed1999

Sequential irrigation with common detergents: a promising new method for decontaminating orthopedic wounds.

This investigation sought to determine the capacity of irrigation solutions in decontaminating orthopedic wounds challenged with a polymicrobial inoculum. Rats were divided into two groups, a control group and a treatment group. After creation of a dorsolumbar incision and placement of a wire through the spinous process, rats were inoculated with Staphylococcus aureus and Pseudomonas aeruginosa. Wounds were irrigated with control or treated solutions. At 2 weeks, cultures were obtained. There were statistically significant differences between groups regarding total number of culture positive sites (P < 0.001), culture-positive animals (P = 0.02), and quantitative cultures (P < 0.02). Sequential irrigation with surfactants lowers bacteria counts recovered from polymicrobial wounds.

Analysis of Variance↗
PubMed1998

Temporary transarticular external fixation of the knee and ankle.

High-energy periarticular fractures of the lower extremity are frequently associated with soft tissue trauma that precludes safe surgical treatment in the early period. A technique of temporary transarticular external fixation is presented that allows stabilization at the appropriate length and alignment while awaiting resolution of soft tissue swelling. The use of these techniques in fifty-seven patients is reviewed and compared with outcome in patients having similar fracture patterns without the use of temporary external fixation.

Ankle Injuries↗
PubMed1998

Indomethacin versus radiation therapy for prophylaxis against heterotopic ossification in acetabular fractures: a randomised, prospective study.

We report a prospective, randomised, blinded clinical comparison of the use of indomethacin or radiation therapy for the prevention of heterotopic ossification (HO) in 75 adults who had open reduction and internal fixation of acetabular fractures through either a Kocher-Langenbeck, a combined ilioinguinal and Kocher-Langenbeck, or an extended iliofemoral approach. Indomethacin, 25 mg, was given three times daily for six weeks. Radiation with 800 cGy was delivered within three days of operation. Plain radiographs were reviewed and given Brooker classification scores by three independent observers who were unaware of the method of prophylaxis. One patient died from unrelated causes and two were lost to follow-up, leaving 72, 33 in the radiation group and 39 in the indomethacin group, available for evaluation at a mean of 12 months (6 to 48). There was no significant difference in the two groups in terms of age, gender, injury severity score, estimated blood loss, delay to surgery, head injury, presence of femoral head dislocation, or operating time, and no complications due to either method of treatment. The final extent of HO was already present by six weeks in all patients who were followed up. Three patients in the radiation group and five who received indomethacin developed HO of Brooker grade III. Two patients in the indomethacin group developed Brooker IV changes; both had failed to receive proper doses of the drug. Cochran-Armitage analysis showed no significant difference between the two treatment groups as regards the formation of HO. Indomethacin and single-dose radiation therapy are both safe and effective for the prevention of HO after operation for acetabular fractures. Radiation therapy is, however, approximately 200 times more expensive than indomethacin therapy at our institution and has other risks.

Acetabulum↗
PubMed1998

A randomized comparison of sequential-gradient calf compression with intermittent plantar compression for prevention of venous thrombosis in orthopedic trauma patients: preliminary results.

Trauma patients with fractures of the pelvis, acetabulum, or femur are at risk for deep venous thrombosis complicating the treatment of their injuries. This risk can be lessened with anticoagulant medications or with mechanical methods such as sequential pneumatic compression. However, many patients in this population group have contraindications to systemic anticoagulation and cannot use sequential limb compression devices because of leg injuries or appliances. Intermittent pneumatic compression of the plantar venous plexus is able to provide prophylaxis against deep venous thrombosis in many of these patients. We performed a prospective, randomized, controlled comparison between plantar compression and leg compression for prevention of deep venous thrombosis in an orthopedic trauma population of 124 patients. Patients were evaluated with duplex ultrasonagraphy at intervals after surgery. Both methods proved protective in comparison with reported rates in patients not given prophylaxis, and although the numbers were too small to give statistically meaningful results, we observed no significant difference in the thrombosis rate (4% for plantar compression versus 0% for leg compression). We conclude that foot pumps are an effective alternative to calf compression for prevention of deep venous thrombosis after a lower extremity fracture.

Adolescent↗
PubMed1998

Benzalkonium chloride. A potential disinfecting irrigation solution for orthopaedic wounds.

The efficacy of benzalkonium chloride was evaluated as an irrigating solution for the eradication of Staphylococcus aureus from a contaminated orthopaedic wound. Thirty Sprague Dawley rats were randomized into two groups. A stainless steel wire was placed in a lumbar spinous process, and the wound was inoculated with 10(7) or 10(6) colony forming units of Staphylococcus aureus. The wound was irrigated with 1 L of normal saline or 0.1% benzalkonium chloride solution. The animals were sacrificed, and cultures were obtained. Rats inoculated with 10(7) colony forming units of Staphylococcus aureus and irrigated with benzalkonium chloride had a significant decrease in the total number of positive cultures, deep wound cultures, and stainless steel wire cultures. Rats inoculated with 10(6) colony forming units of Staphylococcus aureus and irrigated with benzalkonium chloride also had a significant decrease in the total number of positive cultures, deep wound cultures, and stainless steel wire cultures. In a parallel noninoculation study, histologic evaluation of tissues did not show toxicity in the rats irrigated with benzalkonium chloride. This study shows that benzalkonium chloride is more effective than normal saline as an irrigating agent for eradicating Staphylococcus aureus from a contaminated orthopaedic wound.

Animals↗
PubMed1998

Foot pump prophylaxis for deep venous thrombosis: the rate of effective usage in trauma patients.

Trauma patients are at risk for deep venous thrombosis (DVT) but often cannot receive systemic anticoagulation therapy. The major reason for failure of mechanical methods of DVT prophylaxis is ineffective usage. It has been postulated that foot pumps may have a better compliance rate than do other devices. One thousand observations were performed on trauma patients in both the intensive care unit (ICU) and on the surgical ward. Foot pumps were applied properly and functioning correctly 59% of the time. Patients in the ICU had significantly better compliance than did patients on the surgical ward. These rates are not better than published rates for other devices for DVT prophylaxis.

Adult↗
PubMed1997

Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model.

Research in improved materials and methods for internal fixation has centered on internal fixators made of bioabsorbable materials such as polylactic acid, polyglycolic acid, and polyparadioxanone. These materials have two problems: the first is a postoperative complication related to a delayed inflammatory response; and the second is low strength characteristics. An alternative material developed to alleviate these problems is a composite of phosphate glass fibers embedded in the polymer polycaprolactone, referred to as PCL. In this study, intramedullary pins made of PCL were compared to stainless steel pins in a rabbit humerus osteotomy model. Specimens were harvested at 0, 6, and 12 weeks postoperatively, radiographs and mechanical testing to failure were performed at each time interval, and tissue was examined microscopically at 6 and 12 weeks. Histologic results showed PCL pins to be well tolerated with minimal inflammation around the pin. Mechanical testing revealed the PCL fixation to be weaker initially than the stainless steel fixation. There was significant stress shielding of stainless-steel-healed rabbit humeri when compared to the PCL/bone humeri. All osteotomies immobilized with PCL healed with abundant periosteal callus production.

Absorption↗
PubMed1997

Intertrochanteric osteotomy for failed internal fixation of femoral neck fracture.

Thirteen patients with failed internal fixation of the femoral neck were treated with valgus intertrochanteric osteotomy performed by one surgeon from 1987 to 1995. The patients ranged in age from 18 to 59 years. The interval from injury to osteotomy ranged from 4 to 54 weeks. With an average followup of 25 months (range, 9-42 months), the femoral neck fracture healed in all patients. Twelve patients returned to being fully weightbearing without pain. The average limb shortening was improved by 1 cm. Seven of eight patients who were employed before their injuries returned to the same occupations. Femoral head collapse because of avascular necrosis developed in one patient 18 months after surgery and return to full activities and in a second patient shortly after the osteotomy. These two patients now have an arthroplasty. The remainder of the patients have done well without requiring additional surgery. Harris hip scores and Short Form 36 Health Status Survey outcome scoring were available to verify the results in 10 patients.

Adolescent↗