Abstract
Background
Nutrient arteries appear as radiolucent lines (Fig. 1) on account of their topography and may erroneously suggest fracture lines.
Question/purpose
(1) How frequently the nutrient artery canals of the femur are seen after cementless THA and their distribution patterns are; (2) How to distinguish visible nutrient artery canal from fracture lines; and (3) Whether clinical significance of the nutrient artery canals of the femur in patients with primary cementless THA is evident or not.
Methods
Between March 2010 and December 2013, 93 patients 102 hips were enrolled for this retrospective analysis. The number, location, direction of obliquity, length of the nutrient artery canals of the femur, the distance between the tip of the greater trochanter and the proximal end of the nutrient artery canal were measured.
Results
The nutrient artery canal of the femur in the cortex on preoperative cross-table lateral hip radiograph (NACL) was seen in 32 of 102 hips (31.4%), the nutrient artery canal of the femur in the medullary cavity on preoperative anteroposterior hip radiograph (NAMA) was seen in 17 hips (16.6%), and the nutrient artery canal of the femur in the medullary cavity on preoperative cross-table lateral hip radiograph (NAML) was seen in 5 hips (4.9%). The nutrient artery canal of the femur in the cortex on anteroposterior hip radiograph was not seen at all. Entire visible NACLs coursed upward obliquely from postero-distal to antero-proximal direction. An average length of NACL was 32.6 ± 13.9 mm and an average distance between the tip of the greater trochanter and the proximal end of the NACL, NAMA and NAML was 130.1 ± 15.8 mm, 105.1 ± 13.4 mm and 102.5 ± 7.4 mm, respectively. NACL was seen postoperatively in 37 of 102 hips (36.3%), in 24 of which (23.5% overall) both ends of the nutrient artery canal were distal to the implant tip and in 13 of which (12.8% overall) one of the ends of the nutrient canal was at least proximal to the implant tip. NAMA was seen postoperatively in 8 of 102 hips (7.8%) and NAML was seen postoperatively in 6 hips (5.9%), in 5 of which (4.9% overall) femoral stems fully masked the nutrient artery canal and in 9 of which (8.8% overall) a nutrient artery canal was visible postoperatively, but its proximal end was not defined because of implant shadowing. The length of stems which fully masked the nutrient artery canals postoperatively were at least 150 mm or larger. Six (5.9%) intraoperative periprosthethic femoral fractures were detected (Fig. 2 and 3). One was type TL, one was type A1, three were type B2 and one was type B3. Type B2 fractures showed new or additional radiolucent lines on intraoperative and/or postoperative radiographs by comparison with the preoperative radiographs.
Conclusions
The knowledge of radiographic features of the nutrient artery canals of the femur may be useful to distinguish them from intraoperative fractures after cementless THA.
