Abstract
Helical plates potentially bypass the medial neurovascular structures of the thigh. Recently, two plate designs (90°- and 180°-helix) proved similar biomechanically behaviour compared to straight plates. Aims of this study were: (1) Feasibility of MIPO-technique with 90°- and 180°-helical plates on the femur, (2) Assessment of distances to adjacent anatomical structures at risk, (3) Comparison of these distances to using medial straight plates instead, (4) Correlation of measurements performed in anatomic dissection with CT-angiography.
MIPO was performed in ten cadaveric femoral pairs using either a 90°-helical 14-hole-LCP (Group1) or a 180°-helical 15-hole-LCP-DF (Group2). CT angiography was used to evaluate the distances between the plates and the femoral arteries as well as the distances between the plates and the perforators. Subsequently, the specimens were dissected, and the distances were determined again manually. Finally, all helical plates were removed, and all measurements were repeated after application of straight medial plates (Group3).
Closest overall distances between plates and femoral arteries were 15 mm (11 − 19 mm) in Group1, 22 mm (15 − 24 mm) in Group2 and 6 mm (1 − 8 mm) in Group3 with a significant difference between Group1 and Group3 (p < 0.001). Distances to the nearest perforators were 24 mm (15 − 32 mm) in Group1 and 2 mm (1 − 4 mm) in Group2. Measurement techniques (visual after surgery and CT-angiography) demonstrated a strong correlation of r2 = 0.972 (p < 0.01).
MIPO with 90°- and 180°-helical plates is feasible and safe. Attention must be paid to the medial neurovascular structures with 90°-helical implants and to the proximal perforators with 180°-helical implants. Helical implants can avoid medial neurovascular structures compared to straight plates although care must be taken during their distal insertion. Measurements during anatomical dissection correlate with CT-angiography.
