Surgical Simulation Maximizing the Use of Fresh-Frozen Cadaveric Specimens: Examination of Tissue Integrity Using Ultrasound.

BACKGROUND: Arthroscopic surgical simulation, including the use of cadaveric tissue, is valuable for training orthopedic surgery residents. However, it is unclear how often fresh-frozen cadaveric tissue can be reused to provide a reproducible model for developing arthroscopic skills. OBJECTIVE: We determined the usefulness of ultrasound in evaluating tissue degradation in fresh-frozen shoulder and knee joints used for surgical simulation. METHODS: Between February 7 and April 11, 2017, orthopedic residents participated in 6 wet lab sessions during 1 rotation. Knee and shoulder specimens were subjected to ultrasound using a SonoSite Edge machine and a linear probe after each freeze-and-thaw cycle. Degradation of each structure was determined based on standards created for living tissue and comparisons to previous images of the same tissue before initial use. RESULTS: Ultrasonographic assessment of the 2 knee and 2 shoulder specimens revealed lost integrity in subcutaneous fat and muscle with evidence of increased hypoechoicity and loss of normal fiber orientation and density in all specimens examined. Tendons, ligaments, cartilage, iliotibial band, and bone did not lose integrity during freezing and thawing. Ultrasonographic assessment revealed no loss of joint structure integrity. However, the intra-articular work assigned for the simulation curriculum had been carried out to a degree that by the third use, little opportunity remained for further arthroscopic practice on that specimen. CONCLUSIONS: In this study, ultrasound findings showed that fresh-frozen shoulder and knee specimens maintained structural integrity useful for simulation training after 3 cycles of freezing.

A biomechanical comparison of all-inside cruciate ligament graft preparation techniques.

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.