The femoral calcar: A computed tomography anatomical study

Abstract

The femoral calcar is a dense internal septum reaching from the femoral neck to the distal part of the lesser trochanter. Our study aimed at providing an exhaustive radio-anatomical description of this structure. One hundred pelvic computed tomography examinations were retrospectively selected to bilaterally evaluate the shape, dimensions, and density of the femoral calcar. Then, its relation to the femoral cavity was assessed by recording the dimensions of the medullary canal at the level of the greatest length of the spur. The femoral calcar exhibited a variable shape classified as ridge-type 17% (34/200), spur-type 66.5% (133/200), and septum-type 16.5% (33/200). Its mean dimensions were: height = 33.03 mm (20-46), length = 9.94 mm (5-16), and thickness = 2.71 mm (1-4). These dimensions were positively correlated to the height and weight of the individuals (P < 0.001) and were higher in males (P < 0.001). Its mean density was 788.5 Hounsfield units (530-1,200). The longest oblique and anteroposterior diameters of the femoral cavity were respectively 38.74 mm (28-51) and 22.04 mm (17-27). The femoral cavity dimensions were positively correlated to the height and weight of the individuals (P < 0.001), to the femoral calcar dimensions (P < 0.001) and were higher in males (P < 0.001). The femoral calcar was constantly identified as a vertical plate of compact bone exhibiting a consistent anatomical pattern, which suggests a significant mechanical function within the upper femur. Our results may lead to a greater understanding of the hip fracture patterns and to alternative designs for hip arthroplasties.

Effect of altered proximal femoral geometry on predicting femoral stem anteversion in patients with developmental dysplasia of the hip

“…A positive correlation between the CF and postoperative stem anteversion has been reported in OA patients [10, 11, 15]. In this study, we also found a strong positive correlation between postoperative stem anteversion and both CF-LFN and CF-CLT in the CF group, supporting that the CF angle influences the version of the effective femoral cavity.…”

“…The calcar femorale (CF) plays an essential role in the initial stability and alignment of femoral stems [10] and has been reported to reduce torsional micromotion between the stem and host bone [11]. Several studies investigated the relationship between CF, femoral anteversion (FA) at various levels, and final stem anteversion using computed tomography (CT) scan in patients with primary osteoarthritis [9, 12–14].…”

Calcar Femorale in Patients with Osteoarthritis of the Hip Secondary to Developmental Dysplasia

“…The calcar femorale can take various shapes, lengths, and thicknesses. Le Corroller et al 18) classified the shape of the calcar femorale into three types among normal hips without osteoarthritis. A ridge type was present in 17.0% of hips, a spur type in 66.5%, and a septum type in 16.5%.…”

“…Third, the original classification of calcar femorale by Le Corroller et al 18) does not offer sufficient reproducibility or reliability due to the lack of objectivity of the classification. We therefore classified the shape of the calcar femorale using a modification of the classification described by Le Corroller et al 18) into “ridge type” for a short and thick structure (< 9 mm), “septum type” for a thin and long structure (≥ 13 mm), and “spur type” for an intermediate structure, for better objectivity. In order to further improve reliability, calcar femorale should be classified after correcting for patient height, not simply by considering its length.…”

“…1E and G ). We classified the shape of the calcar femorale according to a modification of the classification described by Le Corroller et al, 18) defining ridge type as short and thick (< 9 mm), septum type as thin and long (≥ 13 mm), and spur type as intermediate between the two ( Fig. 1A–C ).…”