Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation.

In this study of bioabsorbable screw fixation of free tendon grafts used in anterior cruciate ligament reconstruction, we performed load-to-failure and cyclic loading of tendon fixation in porcine bone. Bone density measurements from dual photon absorptometry scans were obtained to correlate bone density with fixation failure. The average density of porcine bone (1.42 g/cm2) was similar to that of young human bone (1.30 g/cm2) and significantly higher than that of elderly human cadaveric bone specimens (0.30 g/cm2). Cyclic loading was performed on free tendon grafts fixed with a bioabsorbable screw alone and on grafts fixed with a bioabsorbable screw and an anchor (polylactic acid ball or cortical bone disk). Stiffness of fixation increased substantially with the addition of a cortical bone disk anchor or polylactic acid ball compared with the interference screw alone. Tensile fixation strength of central quadriceps free tendon and hamstring tendon grafts were significantly superior in porcine bone of density similar to young human bone than in elderly human cadaveric bone. The bioabsorbable interference screw yielded loads at failure comparable with traditional bone-tendon-bone and hamstring tendon fixation when controlled for bone density. The addition of a cortical bone disk anchor provided the most optimal fixation of free tendon with the bioabsorbable screw and reduced slippage with cyclic loading to a very low level.

Risk factors for Amphotericin B-associated nephrotoxicity.

PURPOSE: A case-control study was performed to identify and quantify risk factors for amphotericin B-associated nephrotoxicity. PATIENTS AND METHODS: Thirty-five patients receiving intravenous amphotericin B for treatment of proven or suspected fungal infection who developed nephrotoxicity (greater than 100% increase in baseline serum creatinine to a level above the normal range) were compared with 60 control patients receiving amphotericin B who did not develop nephrotoxicity. Amphotericin B dosing variables and other potential risk factors were analyzed in a logistic regression model. RESULTS: Cases of nephrotoxicity received a significantly higher average daily dose of amphotericin B (0.49 +/- 0.18 mg/kg/day) than did controls (0.34 +/- 0.17 mg/kg/day). In a multivariate model, the risk of nephrotoxicity increased 3.7-fold for each 50-mg increase in total dose for a fixed duration of therapy and patient weight. Risk decreased by a factor of 0.4 for each extra day of therapy for a fixed total dose and weight. An increase in weight was also protective when the two other dosage variables were held constant. Each 0.10 mg/kg/day dose increment was associated with a 1.8-fold (95% confidence interval, 1.2 to 2.7) increase in the risk of nephrotoxicity. Other significant risk factors included diuretic use during amphotericin B therapy (12.5, 1.7 to 94.7), for which a linear dose-response relationship was demonstrated, and an abnormal baseline serum creatinine level (15.4, 1.4 to 173.2). CONCLUSION: Risk factors for amphotericin B-associated nephrotoxicity include higher average daily doses (approximately a doubling for each 0.10 mg/kg/day increment), diuretic use, and abnormal baseline renal function. These data suggest possible protective interventions and will aid clinicians in assessing the risk-benefit ratio of amphotericin B therapy for deep fungal infection.