1. An implant (1; 100) of a joint for implantation inside the bone, comprising: a rod (10) having a proximal section (11) and a distal section (15); at least two grooves (12), which essentially extend in the longitudinal the direction of said rod (10); a first coating (14) at least partially covering the surface (14) of said elongated grooves (12); a ridge-shaped protrusion (13), wherein said ridge-shaped protrusion is formed between adjacent grooves (12) and has an apical surface (13a); wherein said apical surface (13a) has an average surface roughness that is lower than the average surface roughness of the first coating (14). 2. An implant (1; 100) according to claim 1, wherein the grooves (12) have a depth of at least 1 mm, preferably at least 2 mm, and even more preferably at least 3 mm. An implant (1; 100) according to claim 1 or 2, wherein said comb-shaped protrusion has such a width that the ratio of the width of the groove (12) to the width of the comb-shaped protrusion (13) is from 0.5 to 5, preferably from 1.5 up to 4.4. An implant (1; 100) according to claim 1 or 2, in which at least one of the grooves (12) is made with the ability to open in its longitudinal direction near at least one of the ends - proximal or distal. An implant (1; 100) according to claim 1 or 2, in which the cross section of at least one of the grooves (12) is constant and / or increases in width near the apical surface (13a) of the ridge-shaped protrusion (13) .6. An implant (1; 100) according to claim 1 or 2, wherein the apical surface (13a) of the ridge-shaped protrusion (13) has an average surface roughness of at least 2.5 μm. The implant (1; 100) according to claim 1 or 2, in which the first coating (14) of the grooves (12) is a titanium-plasma coating,1. Имплантат (1; 100) сустава для вживления внутрь кости, содержащий:стержень (10), имеющий проксимальный участок (11) и дистальный участок (15);по меньшей мере, две бороздки (12), которые по существу проходят в продольном направле