The graft/femoral tunnel angles in posterior cruciate ligament reconstruction: a comparison of 3 techniques for femoral tunnel placement.

This study compared the graft/femoral tunnel angle produced with the outside-in technique with the inside-out technique at 90 degrees and 120 degrees of flexion. Three femoral tunnels were marked with guidewires and measured radiographically in 8 fresh-frozen cadaveric knees using both techniques. Results were analyzed. The mean graft/femoral tunnel angle was 34.4 degrees +/- 14.4 degrees for the outside-in technique, 52.3 degrees +/- 14.1 degrees for the inside-out technique at 120 degrees of flexion, and 74.4 degrees +/- 11 degrees for the inside-out technique at 90 degrees of flexion. The angle was smaller for the outside-in technique versus the inside-out technique at both 120 degrees (P = .019) and 90 degrees of knee flexion (P < .001). The outside-in technique for femoral tunnel placement produces the lowest graft/femoral tunnel angle in cadavers. With the inside-out technique, 120 degrees of flexion produces smaller angles than does 90 degrees of flexion. The outside-in technique results in lower angles and perhaps lower graft failure rates. However, additional clinical studies are needed.

A biomechanical study of plate versus intramedullary devices for midshaft clavicle fixation.

BACKGROUND: Non-operative management of midshaft clavicle fractures is standard; however, surgical management is increasing. The purpose of this study is to compare the biomechanical performance of plate versus intramedullary fixation in cyclic bending for matched pairs of cadaveric clavicles. We hypothesized that the biomechanical properties are similar. METHODS: Eight sets of matched clavicles with vertical, midshaft osteotomies were prepared from fresh, frozen cadavers. A 3.5 mm dynamic compression plate or a 3.8 or 4.5 mm intramedullary device were used for fixation. Clavicles were loaded in a four-point bend at 6 different loads for 3000 cycles at 1 Hz starting with 180 N and increasing by 180 N with sampling at 2 Hz. Failure was defined as 10 mm of displacement or catastrophic construct failure prior to 10 mm of displacement. RESULTS: Between constructs, there was a significant difference with large effect size in displacement at fixed loads of 180 N (P = 0.001; Cohen's d = 1.85), 360 N (P = 0.033; Cohen's d = 1.39), 540 N (P = 0.003; Cohen's d = 0.73) and 720 N (P = 0.018; Cohen's d = 0.72). There was a significant difference with large effect size in load at fixed displacements of 5 mm (P = 0.001; Cohen's d = 1.49), 7.5 mm (P = 0.011; Cohen's d = 1.06), and 10 mm (P = 0.026; Cohen's d = 0.84). CONCLUSION: Plate constructs are superior in showing less displacement at fixed loads and greater loads at fixed displacements over a broad range of loads and displacements with cyclic four-point bending. The clinical relevance is that plate fixation may provide a stronger construct for early rehabilitation protocols that focus on repetitive movements in the early pre-operative period.