Carl L. Nelson

The treatment of experimental osteomyelitis by surgical debridement and the implantation of calcium sulfate tobramycin pellets.

Calcium sulfate was used as a biodegradable delivery system for the administration of antibiotics in musculoskeletal infection. New Zealand white rabbits were infected with Staphylococcus aureus, debrided, and randomized to one of four treatment groups: calcium sulfate pellets with 10% tobramycin sulfate, placebo calcium sulfate pellets and IM tobramycin, placebo calcium sulfate pellets, or debridement. Serum and wound exudate tobramycin concentrations and serum calcium levels were measured. Radiographs, cultures, and histology were analyzed for efficacy and treatment. Rabbits treated with 10% tobramycin sulfate pellets showed a significantly higher eradication of infection (11/13) than rabbits treated with debridement only (5/12), placebo pellets and IM tobramycin (5/14), or placebo pellets (3/13). In the group receiving 10% tobramycin sulfate pellets, serum tobramycin concentrations peaked 3 h post‐operatively at 5.87 μg/ml and were non‐detectable after day 1. In the group receiving placebo pellets and IM tobramycin, serum concentrations peaked at 7.82 μg/ml 1 h post‐operatively, fell to 6.12 μg/ml on day 2, and averaged 4.18 μg/ml for the remainder of the treatment period. The wound exudate tobramycin concentrations in the animals treated with tobramycin sulfate pellets peaked at 11.9 mg/ml on day 1 and dropped to 2.5 μg/ml on day 7. There was no significant difference in the serum calcium levels in any of the treatment groups. Calcium sulfate containing tobramycin sulfate has potential utility as a biodegradable local antibiotic delivery system in the treatment of musculoskeletal infections.© 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

Perioperative asymptomatic venous thrombosis: Role of duplex scanning versus venography * **

We compared combined B-mode/Doppler (duplex ultrasonic scanning and venography in routine preoperative and postoperative screening for major proximal deep vein thrombosis in 78 patients undergoing total hip or knee arthroplasty. Of 309 extremity examinations, duplex scanning had an overall sensitivity of 85.7% (12/14) and a specificity of 97.3% (287/295). The preoperative prevalence and postoperative incidence of major deep vein thrombosis were 2.5% and 14.1% of patients, respectively, despite intensive mechanical and pharmacologic prophylaxis. In addition, venography documented a preoperative prevalence and postoperative incidence of isolated calf deep vein thrombosis in 2.5% and 16.7% of patients, respectively. Whereas such disease extended proximally even in the absence of anticoagulation in only 18% of patients studied by serial duplex scans, calf deep vein thrombosis accounted for the only two instances of pulmonary embolism in this study. There were no deaths related to pulmonary embolism. This study suggests that duplex scanning is useful in screening for perioperative deep vein thrombosis in patients undergoing total hip or knee arthroplasty, which carries a significant risk of venous thromboembolism despite routine prophylaxis.

Prophylaxis against infection in total joint arthroplasty. One day of cefuroxime compared with three days of cefazolin.

The efficacy of cefuroxime was compared with the efficacy of cefazolin for prophylaxis against postoperative wound infection in a prospective, double-blind, multicenter study of 1354 patients who had had elective primary or revision total hip or knee arthroplasty. The patients were randomly assigned to receive either 1.5 grams of cefuroxime followed by 750 milligrams eight and sixteen hours later (for a total of one day of antibiotic treatment), or one gram of cefazolin every eight hours for nine doses (for a total of three days of antibiotic treatment). The first dose of each drug was administered fifteen to sixty minutes before the operative incision was made (for a primary operation) or after tissue samples had been obtained for culture (for a revision procedure). After the operation, the patients were assessed daily while hospitalized and then at two to three months and one year after the operation. Demographic characteristics and risk factors were similar in the two groups. For the patients who had had a primary hip arthroplasty, the rate of deep wound infection was 0.5 per cent (one of 187) for those who had received cefuroxime and 1.2 per cent (two of 168) for those who had received cefazolin. For the patients who had had a primary knee arthroplasty, the rate of deep wound infection was 0.6 per cent (one of 178) for those who had received cefuroxime and 1.4 per cent (three of 207) for those who had received cefazolin.(ABSTRACT TRUNCATED AT 250 WORDS)

Is anticoagulation indicated for asymptomatic postoperative calf vein thrombosis

The purpose of this study was to determine the effect of anticoagulation on the incidence of thrombotic propagation and pulmonary embolism in patients with calf vein thrombosis after total hip or total knee arthroplasty. Patients undergoing arthroplasties had prospective surveillance for postoperative deep vein thrombosis by both bilateral contrast venography and venous duplex scanning. Calf vein thrombosis was documented by venography in 42 patients (50 limbs), including 29 of 253 patients undergoing total hip arthroplasty (11.4%) and 13 of 99 patients undergoing total knee arthroplasty (13%). Of patients on whom follow-up duplex scans were performed, heparin followed by warfarin anticoagulation was used in 11 (13 limbs) and withheld in 21 (25 limbs). Propagation of thrombosis to the popliteal or superficial femoral vein or both was detected by serial duplex scanning in 3 of 13 treated limbs (23%) and 2 of 25 untreated limbs (8%), (p = 0.43). All thrombus propagations were detected within 2 weeks of the operative procedure. There were no pulmonary emboli or deaths. Propagation of asymptomatic calf vein thrombosis after arthroplasty was not influenced by anticoagulation, suggesting that postoperative calf vein thrombosis need not be routinely treated. Serial venous duplex scanning is useful to identify the occasional patient in whom thrombotic propagation requiring anticoagulation develops.

Detecting bacterial colonization of implanted orthopaedic devices by ultrasonication.

Glycocalyx-producing bacteria have been observed on orthopaedic devices that were removed for reasons other than infection. It has been suggested that the bacteria adhere to foreign surfaces within a biofilm and elude standard culture techniques. The authors adapted previously used ultrasonication protocols that disrupt the surface biofilm before culturing removed orthopaedic devices from patients without clinical evidence of infection. Patients having revision total joint arthroplasty of the hip or knee who lacked current or prior clinical evidence of infection were studied prospectively. During surgery, the femoral component and a corresponding control femoral implant were placed in separate sterile bags of saline. The implant and saline combination was placed in an ultrasonication bath for 30 minutes at 60 Hz. The saline solution was passed through a 0.45-μm pore filter, and the filter residue was cultured on sheep blood agar. None of the 21 implants yielded positive culture on routine microbiologic testing. However, using the ultrasonication protocol, a coagulase-negative Staphylococcus grew from one of the removed implants. Numerous total joint implant failures that are attributed to aseptic loosening may be a result of subclinical infection from bacteria within a biofilm. The current study supports the concept that biofilm-protected bacterial colonization of implants may occur without overt signs of infection and ultrasonication can be used to enhance identification of these bacteria.

Nightly enteral nutrition support of elderly hip fracture patients: a phase I trial.

OBJECTIVE This non-blinded randomized controlled trial was the first phase of a planned series of investigations designed to test the efficacy of aggressive post-operative enteral nutrition support to decrease the rate of post-operative complications or improve long-term outcomes in specifically defined subgroups of elderly patients who have sustained a hip fracture requiring surgery. METHODS Eighteen patients (17 males) were randomized to the treatment (eight male subjects) or control groups. The control group (mean age 76.5+/-6.1 years) received standard post-operative care. Subjects in the treatment group (mean age 74.5+/-2.1 years) received 125 cc/hour of nasoenteral tube feedings over 11 hours each night in addition to standard post-operative nutritional care. RESULTS Both the treatment and control groups had reduced volitional nutrient intakes for the first 7 post-operative days (3,966+/-2,238 vs. 4,263+/-2,916 kJ/day [948+/-535 vs. 1019+/-697 kcal/day], p=0.815), but the treatment subjects had a greater total nutrient intake (7,719+/-2,109 vs. 4,301+/-2,858 kJ/day [1845+/-504 vs. 1028+/-683 kcal], p=0.012). On average, treatment subjects were tube fed for 15.8+/-16.4 days. There was no difference between the groups (treatment vs. controls) in the rate of post-operative life-threatening complications (25 vs. 30%, p=1.00) or in-hospital mortality (0 vs. 30%, p=0.216). Mortality within 6 months subsequent to surgery was lower in the treatment group compared to the controls (0 vs. 50%, p=0.036). DISCUSSION We conclude that nightly enteral feedings are a safe and effective means of supplementing nutrient intake. The greatest impact of nutrition support may be to reduce mortality.

RESURFACING OF ONLY THE FEMORAL HEAD FOR OSTEONECROSIS : LONG-TERM FOLLOW-UP STUDY

Fourteen patients (21 hips) with osteonecrosis of the femoral head with collapse had the femoral head resurfaced with a cemented titanium shell. All of the femoral heads were Ficat stage III or IV. Of the 21 surgeries, 7 were failures. Treatment for all 4 patients with sickle cell disease or trait failed (100%). When the cases of 17 patients who did not have sickle cell disease or trait were reviewed separately, the success rate was 14 of 17 (82%). The follow-up periods (all > 5 years) of the 14 successful patients in this group averaged 6.2 years, and their average Harris hip score was 87 (10 excellent, 4 good). Of the 14 successes, 10 patients had a follow-up period longer than 5 years (average, 7.7 years) and an average Harris hip score of 94 (7 excellent, and 3 good). There was no evidence of loosening and there was no osteolysis. It is concluded that this operation provides an alternative to hemiarthroplasty, total joint arthroplasty surgery, or bipolar arthroplasty. This is a time-buying first-stage operation and, for younger patients, will not last a lifetime. The concept appears prudent because the surgical procedure is directed at the site of primary disease, the femoral head.

Revision total hip arthroplasty using ultrasonically driven tools. A clinical evaluation.

A three-center clinical evaluation of the use of ultrasonic instrumentation for cement removal during 90 revision total hip arthroplasties was undertaken. In conjunction with hand tools, cement removal was facilitated with ultrasonic tools. Superficial bone burns were seen in eight cases (9%). Bone perforations were created with ultrasonic tools in three cases (4%)--two followed perforations already created by hand tools in the proximal metaphyseal area. Only one perforation (1%) was made in the shaft of the femur. Ultrasonic instrumentation is a valuable adjunct for cement removal in revision total hip arthroplasty.

Ten strategies to reduce blood loss in orthopedic surgery.

In any operative procedure, careful surgical dissection with precise hemostasis is one of the most effective ways to minimize surgical blood loss and reduce the need for allogeneic red blood cell transfusion. Several other techniques contribute to reduce blood loss in major orthopedic procedures. These techniques are reviewed and include rehearsal of the procedure and positioning the patient to reduce venous engorgement. In addition, a case report is presented that demonstrates the feasibility of revision hip replacement surgery without the use of transfusion in a Jehovahs Witness patient.

Nightly Enteral Nutrition Support of Elderly Hip Fracture Patients: A Pilot Study

Objectives: Assess whether postoperative nightly enteral nutrition support improves outcomes of elderly patients with an acute hip fracture Design: Randomized controlled trial Setting: A University and a Department of Veteran’s Affairs Hospital Subjects: Adults >64 years of age who underwent surgical repair of an acute hip fracture Interventions: Subjects randomized to the control (Ctrl) group received standard care while the treatment (Tx) group received standard care plus up to 1,375 Kcal [5,755 kJ/d] of nasoenteral tube feedings each night. When tube feedings had to be discontinued, Tx subjects were asked to drink an equivalent amount of the nutritional supplement each night. Measures of Outcome: Rate of postoperative complications and 6-month postoperative survival Results: Fifty-seven patients were randomized to the Tx (n = 27, mean age 75.9 ± 7.4 yrs) or Ctrl groups (age 81.7 ± 7.7 yrs). All subjects had reduced volitional nutrient intakes after surgery. During the first week subsequent to surgery, there was no difference between the treatment and control groups in the amount of nutrients that they volitionally consumed during the day. However, the treatment subjects had a greater total daily nutrient intake (Median 5,866 (IQR 5,024 to 7,335) kJ/d vs. 3,965 (IQR 2,968 to 4,664) kJ/d, p < 0.001). However, by the second postoperative week this difference was no longer statistically significant. Intolerance to the tube feedings developed commonly. There was no difference between the groups in the rate of postoperative life-threatening complications or mortality within six months subsequent to surgery. Conclusions: This study failed to confirm findings from a prior study of improved postoperative survival with nutrition support. However, it was conducted on multiple hospital wards which may have contributed to the higher rate of tube-related problems and less nutrient delivery signifying the need for further study.