Biomechanical evaluation of locked plating in proximal humeral fractures

The aim of the study was to examine the correlation between the chosen position of screws and the complications observed in patients who underwent locked plating of proximal humeral fractures. We evaluated radiographs of 367 patients treated by locked-plating for proximal humeral fractures. Radiographs were taken at one day, 6 weeks, 3 months and 6 months after surgery, and were analyzed for secondary fracture displacement, loss of fixation, cutting out of screws and necrosis of the humeral head. Secondary loss of fixation occurred in 58 cases (15.8%) and among those cutting out of screws was observed in 25 cases (6.8%). In cases of secondary loss of fixation a mean of 6.7 screws were used to fix the fracture (<em>vs</em> 6.6, P=0.425). There was neither significant correlation between position of screws and the occurrence of postoperative loss of fixation in Spearman correlation nor relationship from backward logistic regression analysis. Loss of fixation following locked plating of proximal humeral fractures does not relate to the number of screws and their positions in the humeral head. In consequence, anatomic fracture reduction and restoration of the humeral head-shaft angle are still important factors and should not be disregarded.

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Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures

Bone and Joint Research ◽

10.1302/2046-3758.76.bjr-2017-0356.r1 ◽

2018 ◽

Vol 7 (6) ◽

pp. 422-429 ◽

Cited By ~ 5

Author(s):

Y. P. Acklin ◽

I. Zderic ◽

J. A. Inzana ◽

S. Grechenig ◽

R. Schwyn ◽

...

Keyword(s):

Motion Tracking ◽

Plate Fixation ◽

Proximal Humeral Fractures ◽

Humeral Fractures ◽

High Rate ◽

Initial Stiffness ◽

Screw Perforation ◽

Optical Motion ◽

Biomechanical Evaluation ◽

Philos Plate

Aims Plating displaced proximal humeral fractures is associated with a high rate of screw perforation. Dynamization of the proximal screws might prevent these complications. The aim of this study was to develop and evaluate a new gliding screw concept for plating proximal humeral fractures biomechanically. Methods Eight pairs of three-part humeral fractures were randomly assigned for pairwise instrumentation using either a prototype gliding plate or a standard PHILOS plate, and four pairs were fixed using the gliding plate with bone cement augmentation of its proximal screws. The specimens were cyclically tested under progressively increasing loading until perforation of a screw. Telescoping of a screw, varus tilting and screw migration were recorded using optical motion tracking. Results Mean initial stiffness (N/mm) was 581.3 (sd 239.7) for the gliding plate, 631.5 (sd 160.0) for the PHILOS and 440.2 (sd 97.6) for the gliding augmented plate without significant differences between the groups (p = 0.11). Mean varus tilting (°) after 7500 cycles was comparable between the gliding plate (2.6; sd 1.9), PHILOS (1.2; sd 0.6) and gliding augmented plate (1.7; sd 0.9) (p = 0.10). Similarly, mean screw migration(mm) after 7500 cycles was similar between the gliding plate (3.02; sd 2.85), PHILOS (1.30; sd 0.44) and gliding augmented plate (2.83; sd 1.18) (p = 0.13). Mean number of cycles until failure with 5° varus tilting were 12702 (sd 3687) for the gliding plate, 13948 (sd 1295) for PHILOS and 13189 (sd 2647) for the gliding augmented plate without significant differences between the groups (p = 0.66). Conclusion Biomechanically, plate fixation using a new gliding screw technology did not show considerable advantages in comparison with fixation using a standard PHILOS plate. Based on the finding of telescoping of screws, however, it may represent a valid approach for further investigations into how to avoid the cut-out of screws. Cite this article: Y. P. Acklin, I. Zderic, J. A. Inzana, S. Grechenig, R. Schwyn, R. G. Richards, B. Gueorguiev. Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures. Bone Joint Res 2018;7:422–429. DOI: 10.1302/2046-3758.76.BJR-2017-0356.R1.

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