78 - Freie Mitteilung
16. Mai 2019, 17:30 - 19:00, Sopra 3, 4. OG
The cortical overlap view – A tool for reproducible determination of the entry point for proximal femoral nailing
K. Boernert1, F. J. Beeres1, C. Jiamton2, R. Babst1, B. C. Link1, Presenter: K. Boernert1 (1Luzern, 2Bangkok/TH)
Implant-related complications after proximal femoral nailing of trochanteric fractures occur in 6 to 21%. Besides appropriate reduction of the fracture, it is crucial to identify the correct entry point for the implant. Accurate intraoperative choice of the entry point is dependent on identification of the tip of the greater trochanter (GT) and requires proper radio-anatomic understanding of the proximal femur. A radiological view was defined to provide readily identifiable radio-anatomic landmarks which allows sound determination of the tip of the GT in the anteroposterior (ap) view. The aim of this study is to characterise this radiological view and test its intra- and inter-observer reproducibility.
Anatomical and radio-anatomical features of 16 cadaveric femurs were analysed. A radiological view was identified that is characterised by the radiological overlap of the density line of the piriformis fossa and the posterior-superior boarder of the GT. It marks the rotation of the proximal femur in which the GT can be accurately identified and safely used to determine the proper entry point for a proximal femoral nail. This view was called cortical overlap view (COV). Five junior and 5 senior orthopaedic trauma surgeons were asked to identify the correct COV in radiological imaging series at the beginning of the study and 4 weeks after. Intra- and interrater reliability was calculated using the intraclass correlation coefficient.
Mean internal rotation of the femur to achieve a correct COV was 17.5° (range 12.8°-21.8°). The mean distance from the cortical overlap line in the correct COV to the tip of the GT was 4.5 mm (range 4.1-4.8mm, CI 95%). Intra-rater and interrater reliability was high with ICC(2,k)= 0,932 (95%CI: 0,826 – 0,985) and ICC(2,k)= 0,987 (95%CI: 0,975 – 0,994), respectively. Junior doctors achieved higher rates of correct identification than senior doctors both in the first and the second round (95% vs. 90% and 90% vs. 86.25%).
The COV is an easily reproducible radio-anatomical landmark allowing accurate identification of the anatomy of the GT. This should assist the operating surgeon to determine the correct entry point for intramedullary nailing, optimise implant positioning and might prevent implant-related complications. Hence, radio-anatomic education of surgeons could help improving the clinical results following proximal femoral nailing.