ABSTRACT
BACKGROUND: The all-inside cruciate ligament graft preparation technique has become popular due to its utility in sparing a growing physis, preserving a tendon in ACL surgery, and/or reduction of pain. However, few studies have compared graft preparation techniques to determine the ideal construct for cruciate ligament reconstruction. We sought to compare biomechanical properties of two quadrupled all-inside cruciate ligament graft preparation techniques and three alternative all-inside graft preparation techniques that may be used when the available tendon is too short to be quadrupled. METHODS: Fifty porcine extensor tendons were evenly divided into five groups (n = 10) representing all-inside graft preparation techniques, including two quadrupled (Quad-A, Quad-B) and three alternative methods (Tripled, Folded, Two-Doubled). Each graft construct underwent preconditioning (10 loading cycles from 20 to 50 N at 0.1 Hz), cyclic loading (500 loading cycles from 50 to 250 N at 1.0 Hz) and load-to-failure (tension applied at 20 mm/min). RESULTS: Quad-A and Quad-B demonstrated no significant differences in cyclic displacement (10.5 ± 0.3 vs 11.7 ± 0.4 mm; p = 0.915), cyclic stiffness (1086.2 ± 487.3 vs 460.4 ± 71.4 N/mm; p = 0.290), pullout stiffness (15.9 ± 4.3 vs 7.4 ± 4.4 N/mm; p = 0.443), ultimate failure load (641.2 ± 84.7 vs 405.9 ± 237.4 N; p = 0.672), or ultimate failure displacement (47.3 ± 6.7 vs 55.5 ± 0.7 mm; p = 0.778). The mean cyclic displacement of the Two-Doubled group was significantly greater than the Quad-A (29.7 ± 2.2 vs 10.5 ± 0.3 mm; p < 0.001), Quad-B (29.7 ± 2.2 vs 11.7 ± 0.4 mm; p < 0.001), Tripled (29.7 ± 2.2 vs 11.3 ± 0.2 mm; p < 0.001), and Folded group (29.7 ± 2.2 vs 13.3 ± 0.2 mm; p < 0.001). There were no other statistically significant differences between the three alternative all-inside graft preparation techniques. CONCLUSION: The current study demonstrates the biomechanical properties of two quadrupled all-inside graft constructs, Quad-A and Quad-B, are not significantly different. When the available tendon is of insufficient length, the Two-Doubled group demonstrated more than twice the cyclic displacement of all other graft preparation techniques, and is therefore not recommended for use in all-inside cruciate ligament reconstruction.
ABSTRACT
In 16 patients with blunt trauma to the chest, the role of cardiovascular nuclear medicine was evaluated using anterior chest flow assessment, with first-pass ejection fraction of left and right ventricles and 99mTc-pyrophosphate scintigraphy. The radiopharmaceutical used was pyrophosphate, labelled with approximately 20 mCi 99mTc. The anterior chest flow and first-pass ejection fractions were initially obtained during the injection of 99mTc-pyrophosphate and were followed up 3 h later by anterior, LAO 45 degrees, and left lateral views of the chest, using an LFOV gamma camera with a data processor. The results were compared with serial cardiac enzymes studies, electrocardiograms and echocardiograms. Of the patients, 77% showed scintigraphic evidence of cardiac contusion. The intensity of activity varied from grades I to II; five patients had abnormal echocardiographic findings. Only two had abnormal ejection fractions, and one patient had evidence of left ventricular aneurysm along with poor ventricular performance. Cardiac enzymes were found to be the least helpful. Electrocardiograms, though non-specific for myocardial damage, were abnormal in 62% of the patients. Eleven of our patients had both abnormal ECG and increased PYP uptake. Even though there is no agreement as to which noninvasive parameter is more sensitive in the diagnosis of myocardial contusion, 99mTc-pyrophosphate scintigraphy, in conjunction with ECG, seems promising in this respect.
