A novel concept for splint fixation of midshaft clavicle fractures: a biomechanical feasibility study.

BACKGROUND

Minimally invasive treatment of clavicle shaft fractures has become increasingly popular due to reduced soft tissue damage, smaller incisions, lower rates of infections, and minimal scarring. Most commonly described options are titanium elastic nailing and plate osteosynthesis. Clinical studies report promising results with good healing tendencies, particularly in children and adolescents. However, there are still some downsides to consider—titanium elastic nails have been associated with soft-tissue irritation, implant associated discomfort, and notable complications rates including lateral perforation of the cortex and medial protrusion of the implant. Implant removal after a few months is standardly carried out, leading to a second surgery with corresponding risks and costs. Furthermore, biomechanical studies report a low rotational stability for these implants. Therefore, the aim of this biomechanical feasibility study was to explore a new concept for minimally invasive splint fixation of clavicle shaft fractures in comparison to the titanium elastic nailing.

METHODS

Twelve anatomical composite clavicles with standardised oblique midshaft fractures AO/OTA 15.2 A were randomized to two groups for fixation with either a 2.5 mm titanium elastic nail (Group 1) or a 5.0 mm rib splint (Group 2). Each specimen underwent (1) non-destructive quasi-static pure-bending tests in anteroposterior and superoinferior directions, followed by (2) non-destructive and (3) progressively increasing cyclic pure-bending loading to failure in superoinferior direction with monitoring of the interfragmentary movements via motion tracking.

RESULTS

Anterior and posterior bending stiffness in Group 2 was significantly higher compared to Group 1, p ≤ 0.030. Superior and inferior bending stiffness, interfragmentary displacements during cyclic testing, and cycles to failure were not significantly different between the groups, p ≥ 0.078.

CONCLUSION

Despite the observed differences in implant thickness and the suboptimal distal design of the rib splint for clavicle anatomy, both tested implants demonstrated comparable biomechanical performance in the current feasibility study. The results should be interpreted with caution and further investigations may help clarify the influence of other factors on implant stability of fixation.