Persistence of bacteria on antibiotic loaded acrylic depots. A reason for caution.

Bacterial growth on the surface of antibiotic loaded acrylic cement was examined in an in vitro model. Tobramycin or vancomycin impregnated discs were incubated in broth containing either Staphylococcus epidermidis or Staphylococcus aureus organisms. At 24, 48, and 96 hours, the broth and the surface of the acrylic discs were examined for viable organisms. In the broth, only 6% (8 of 136) of samples contained viable organisms at 24 hours, and all samples were sterile by 96 hours. This is in contrast to the surface of the discs, which revealed the presence of viable organisms at all study time periods. Growth was noted in 99% and 30% of the Staphylococcus epidermidis and Staphylococcus aureus discs, respectively, at 24 hours. Viable organisms were found on both types of discs through 96 hours (20% of Staphylococcus epidermidis and 15% of Staphylococcus aureus). The surface of bone cement is therefore a suitable substrate for bacterial growth, even in the presence of antibiotics. In clinical practice, antibiotic loaded acrylic cement should therefore be used with caution and clear indications.

Bacterial growth on antibiotic-loaded acrylic cement. A prospective in vivo retrieval study.

Twenty-three patients with intraoperative culture-proven periprosthetic infection of the hip or knee were enrolled in a prospective cement retrieval study. All were treated with a two-stage technique using antibiotic-loaded acrylic cement as an antibiotic depot. Staphylococcus epidermidis was the most commonly isolated organism (19 of 23 cases). Cement and tissue were examined at second-stage revision for the presence of viable organisms. In this series, no organisms were isolated from the surface of the cement, a 100% concordance with the tissue cultures. A subsequent failure rate of 4.4% (1 case) was seen in this series. Investigation suggests this may represent reinfection from a new strain of organism rather than failure of eradication of the original infection.

Temporary antibiotic loaded acrylic hip replacement: a novel method for management of the infected THA.

Postoperative infection after hip joint replacement is an uncommon but potentially devastating complication in contemporary orthopaedics. Management in two stages is the more favored approach in North America. This introduces difficulty with patient management in the interval between stages, delays rehabilitation, and introduces technical difficulty during the second stage. A method has been developed whereby a temporary antibiotic-loaded facsimile of the hip is introduced at the first stage, designed to maintain stability of the joint, length of the limb, and mobility of the patient. It has been used in a total of 86 cases to date. The results in 46 cases with a minimum follow-up of 2 years are reviewed in this article. The infection was controlled in 93.5% of cases.

Two-stage exchange arthroplasty using a functional antibiotic-loaded spacer in the treatment of the infected knee replacement: the Vancouver experience.

Two-stage exchange arthroplasty is currently the method of choice in the treatment of the infected knee replacement. The prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) is a temporary, antibiotic-loaded functional prosthesis that is used as an interim spacer in two-stage exchange arthroplasty. In this prospective series, we report on the early results of the use of the PROSTALAC knee spacer in two-stage exchange arthroplasty of infected knees. A total of 24 knees were treated with this prosthesis, and were reviewed at a mean follow-up time of 2.2 years. Infection was controlled in all but 2 knees, for an infection cure rate of 91.7%. The patients' function was improved between stages, and motion was maintained in the majority of cases. The significant complications with the PROSTALAC implant in place were tibio-femoral instability, which was corrected with a design modification, and patellar instability, which continues to be a problem. These complications were transient and were not of any significance after the second stage.

The role of arteriography in assessing vascular injuries associated with dislocations of the knee.

All patients with a diagnosis of knee dislocation during a 7 1/2-year period (1984-1991) were reviewed retrospectively. There were 37 knee dislocations (KDs) in 35 patients. The mechanism of injury was predominantly motor vehicle or pedestrian crashes. Popliteal artery injury was present in 6 of 37 (16%). There was no significant vascular injury in 31 of 37 knee dislocations as evidenced by normal arteriograms or absence of vascular complications on follow-up. Of those with no significant vascular injury, 3 of 31 had limb ischemia that improved with reduction of the KD, had normal arteriograms, and had no further vascular treatment. All patients with popliteal artery injury had a pulse deficit (five of six) or a documented history of ischemia (six of six). In the absence of these findings, no patient was found to have an arterial injury. Arterial injuries were treated with interposition (five of six) or bypass graft (one of six) and fasciotomies (six of six). Amputation was required in one of six of the vascular injury group and none of 31 of the remainder of the patients with no vascular injury. We recommend the selective use of arteriography in patients with KDs based on a history or clinical findings of ischemia and do not recommend routine arteriography for all patients with KD.

Postinfarction cardiac rupture: surgical success and review of the literature.

Cardiac rupture following myocardial infarction has been reported as the cause of 4 to 24% of all infarction deaths. The rupture may occur from a few hours to several days after the myocardial infarction and is not a true "blowout" but rather a necrotic hemorrhagic area in the center of the infarction that extravasates blood and leads to pericardial tamponade. The most common findings when rupture occurs are renewed chest pain, bradycardia, and shock. Two patients with postinfarction myocardial rupture who were operated on successfully are reported. With prompt diagnosis and treatment, more of these patients would survive long enough to undergo operation. With cardiopulmonary bypass the repair of these ruptures is not difficult.

Surgical treatment for ventricular aneurysm.

The results of 110 patients with ventricular aneurysm treated surgically are discussed. The overall mortality in this group was 11.8 per cent. Since the use of coronary bypass operation and the intra-aortic balloon pump, the mortality has been significantly reduced.

Acute myocardial infarction: a surgical emergency.

Preservation of viable myocardium is the primary goal of coronary artery surgery. Our total experience with coronary artery bypass grafting is 1,612 patients, operated upon from March 13, 1969, through Jan. 31, 1975 (2.85 per cent over-all mortality rate). Four hundred thirteen patients were operated upon on an emergency basis. Of this group, 96 were having acute myocardial infarctions and 317 were in the preinfarction syndrome. Emergency coronary artery bypass surgery was performed with 5 deaths (5.2 per cent) in the acute myocardial infarction group and 4 deaths in the preinfarction group (1.26 per cent). These patients had a much lower mortality rate than that of medically treated patients in the acute myocardial infarction group. Postoperative catheterization studies on the acute myocardial infarction group showed a 96 per cent rate of primary graft patency. Follow-up studies through 3 years, 10 months show only 1 late death (4 months after the operation). The in-hospital and the first year mortality rates in a medically treated group with acute myocardial infarction were compared with the surgically treated group. The result was a mortality rate of 30 per cent with medical treatment and 6.3 per cent with surgical treatment. Actuarial analysis demonstrated a greater than 20 per cent difference in mortality rate at 1 year, in favor of surgical treatment. The lower surgical mortality coupled with the early and late clinical results prove that emergency coronary bypass is superior therapy in selected patients with acute myocardial infarction.