Anatomical implications of the subvastus approach on major vascular injury during a distal femoral osteotomy: a computed tomographic venography study.

PURPOSE

This study evaluated major vascular injury risk in distal femoral osteotomy (DFO) via the subvastus approach and examined the relationship between the posterior border of the vastus medialis (VM) and the superficial femoral artery (SFA) and vein (SFV).

METHODS

Eighty limbs from 80 patients were evaluated using lower extremity computed tomographic venography. The positional relationship between the VM, SFA, and SFV was evaluated by measuring the angle between each structure and the horizontal reference point (VMA: VM angle, FAA (femoral arterial angle), FVA (femoral venous angle) and the distance between VM and the SFA and SFV (VMAD: VM-arterial distance, VMVD: VM-venous distance) in each axial slice (0/10/20/30/40 mm) proximal to the level of the superior patellar margin. The proximity of the posterior border of the VM and the SFA/SFV as a vertical distance, measured between the slice of the superior border of the patella and the slice where the posterior border of the VM contacted the SFA was evaluated. Single and multiple regression analyses were performed using the vertical distance as the objective variable.

RESULTS

As the slice shifted proximally, the VMA significantly increased (24.9 ± 8.5, 36.3 ± 8.8, 47.4 ± 11.8, 59.9 ± 14, 70.3 ± 13.7 degrees, respectively, p < 0.001 between all slices) and moved posteromedially from a medial direction. FAA (94.2 ± 7, 86.9 ± 9.2, 78.4 ± 9.7, 71.4 ± 9.8, 66.6 ± 10.5 degree, respectively, p < 0.001 between all slices) and FVA (100.6 ± 4.9, 98.3 ± 5.9, 93.7 ± 7.5, 88 ± 9.2, 81.1 ± 10.5 degrees, respectively, p < 0.001 between all slices) decreased and moved from a posterolateral to a posteromedial direction, while VMAD (35.4 ± 7.8, 24.1 ± 7.3, 14.3 ± 6, 8.4 ± 7, 6.2 ± 6.3 mm, respectively, p < 0.001 between all slices) and VMVD significantly decreased (42.7 ± 7.3, 32 ± 7.4, 22.4 ± 6.8, 14.5 ± 10.6, 8.7 ± 7.1 mm, respectively, p < 0.001 between all slices). The average vertical distance was 36 ± 9.3 mm (range 18.6-61.5 mm). The body height and the patellar length significantly affected the vertical distance.

CONCLUSION

The posterior border of the VM shifted posteromedially from distal to proximal and contacted the SFA at an average of 36 mm from the suprapatellar border. Surgeons should be aware of the risk of major vascular injury during exposure and osteotomy.

LEVEL OF EVIDENCE

Case series, Level IV.