Biomechanical assessment of the NCB-PH plate in proximal humeral fractures, and anatomic study for its application technique
LicenseStandard (Fassung vom 03.05.2003)
The NCB-PH (Non contact bridging-proximal humerus) plate is a locked plate used for fixation of proximal humeral fractures especially in osteoporotic bones. It can be applied through a MIS (minimally invasive surgical) technique thus avoiding the use of the extensive deltopectoral approach. The aim of this work was to study the biomechanical advantages of such new locked plate in the fixation of proximal humeral fractures in osteoporotic bones and the safety of its MIS technique of application regarding the risk of injury to the axillary nerve. 8 pairs of fresh-frozen osteoporotic cadaveric humeri were used for the biomechanical study. For each bone an AO-11 B1 fracture with head impaction was created. The bones were then reduced anatomically and fixed with the NCB-PH plate. For each pair, one bone was fixed with the plate in the locked mode and the other in the non-locked mode. The bones were then loaded axially for 100 cycles with a force up to 120 N and the interfragmentary motion between the head and shaft was measured using the Zebris 3-D motion analyzer. As for the anatomical study, the plate was applied using the guidelines for its MIS technique in the 10 limbs of 5 fresh cadavers and then the axillary nerve was dissected to assess its integrity. Interfragmentary motion was found to be less in the group fixed with the plate in the locked mode compared to the non-locked mode. This occurred in both rotation and translation. This difference was statistically significant for the 3 planes of rotation, but only for the sagittal plane of translation. Using the MIS technique, there was one case of partial injury of the axillary nerve and it was totally intact in the other 9 limbs. The NCB-PH plate is a suitable implant for fixation of proximal humeral fractures in osteoporotic bones. The locked mode has biomechanical advantages especially in limiting the interfragmentary rotational motion. Its MIS technique of application is safe provided that the guidelines are strictly adhered to.
Subject HeadingsOberarmbruch [GND]
Shoulder fractures [MeSH]