Fractures of the proximal humerus are difficult to treat because of the fragility of the fragments and of their blood supply. A number of methods have been devised which use threaded wires placed transcutaneously. Some wire configurations have been augmented by external fixator devices, which link together the lateral ends of the wires. This study tested the hypothesis that a wire plus external fixator configuration could be found, which gives fracture stability equivalent to a plate and screw construct. Methods 72 artificial humeri received a standardized sloping osteotomy, simulating a two-part fracture. These were fixed using: 2.5mm terminally threaded pins in Box and Fan configurations; 3mm fully threaded pins in Box and Fan configurations with or without external fixator; 2.5mm and 3mm Up-Down configuration. One group had bone plate and screws constructs. The constructs underwent cyclic loading in torsion and varus axial compression/bending, followed by loading to failure. Results In cyclic torsion the 2.5 and 3mm Fan constructs had significantly lower stiffness than all other constructs (p<0.05). Adding an external fixator increased the torsional stiffness of the 3mm Fan group from 1.2 to 2.6 Nm/deg (p=0.12) and gave a significantly higher torsional stiffness for the Box group (p=0.03). In cyclic axial compression plus varus bending test the Box and Fan constructs had a higher stiffness (p=0.08) when augmented with an external fixator. These constructs were stiffer than the Plate (p=0.07) and Up-Down constructs. The 3mm Box with and without the external fixator and the Plate groups had a ultimate load of 2000, 2068 and 2070 N respectively (p>0.05). Four 3 mm threaded wires in a parallel ‘box’ configuration plus external fixator gave mechanical performance which did not differ significantly from the plate and screws construct. Conclusions When four 3 mm fully-threaded wires were placed in the box configuration and linked by an external fixator, the stiffness and strength of the construct did not differ significantly from that of the bone plate and locking screws constructs.

The stability of percutaneous fixation of proximal humeral fractures

CASTOLDI, Filippo;ROSSI, Roberto;
2010-01-01

Abstract

Fractures of the proximal humerus are difficult to treat because of the fragility of the fragments and of their blood supply. A number of methods have been devised which use threaded wires placed transcutaneously. Some wire configurations have been augmented by external fixator devices, which link together the lateral ends of the wires. This study tested the hypothesis that a wire plus external fixator configuration could be found, which gives fracture stability equivalent to a plate and screw construct. Methods 72 artificial humeri received a standardized sloping osteotomy, simulating a two-part fracture. These were fixed using: 2.5mm terminally threaded pins in Box and Fan configurations; 3mm fully threaded pins in Box and Fan configurations with or without external fixator; 2.5mm and 3mm Up-Down configuration. One group had bone plate and screws constructs. The constructs underwent cyclic loading in torsion and varus axial compression/bending, followed by loading to failure. Results In cyclic torsion the 2.5 and 3mm Fan constructs had significantly lower stiffness than all other constructs (p<0.05). Adding an external fixator increased the torsional stiffness of the 3mm Fan group from 1.2 to 2.6 Nm/deg (p=0.12) and gave a significantly higher torsional stiffness for the Box group (p=0.03). In cyclic axial compression plus varus bending test the Box and Fan constructs had a higher stiffness (p=0.08) when augmented with an external fixator. These constructs were stiffer than the Plate (p=0.07) and Up-Down constructs. The 3mm Box with and without the external fixator and the Plate groups had a ultimate load of 2000, 2068 and 2070 N respectively (p>0.05). Four 3 mm threaded wires in a parallel ‘box’ configuration plus external fixator gave mechanical performance which did not differ significantly from the plate and screws construct. Conclusions When four 3 mm fully-threaded wires were placed in the box configuration and linked by an external fixator, the stiffness and strength of the construct did not differ significantly from that of the bone plate and locking screws constructs.
2010
92 Suppl. 2
90
97
Castoldi F; Bonasia DE; Blonna D; Rossi R; Dettoni F.; Assom M; Sankey A.; Halewood C; Amis A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/136560
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