A self-adjusting spacer device , comprising: a bushing , forming a cavity having a first longitudinal axis (B) between a proximal bushing end and a distal bushing end, further comprising at least one opening, a flange member at said proximal bushing end and at least one internal first coupling member ; a pin , having a second longitudinal axis (C) between a head portion and a shank portion , said shank portion further comprising at least two external threaded portions , each partially circumferentially extending on a surface of said shank , and at least one second coupling member which is adapted to operably engage with said internal first coupling member of said bushing so as to allow translational but prevent rotational movement of said pin relative to said bushing ; a locking member , having a bore along a third longitudinal axis (D) between a proximal surface and a distal surface, and at least two internal threaded portions , each partially circumferentially extending on a surface of said bore ; wherein, when assembled, said locking member is coaxial with said bushing and said pin and operably coupled to said bushing via a coupling mechanism configured to allow rotational movement of said locking member relative to said bushing about said third longitudinal axis (D) between an adjustment position , where said at least two internal threaded portions of said locking member do not engage with respective said at least two external threaded portions of said shank portion , and a locking position , where said at least two internal threaded portions of said locking member operably engage with said at least two external threaded portions of said shank portion , characterized in that said coupling mechanism is further configured to prevent translational movement along said third longitudinal axis (D) of said locking member relative to said bushing . a bushing , forming a cavity having a first longitudinal axis (B) between a proximal bushing end and a distal bushing end, further comprising at least one opening, a flange member at said proximal bushing end and at least one internal first coupling member ; a pin , having a second longitudinal axis (C) between a head portion and a shank portion , said shank portion further comprising at least two external threaded portions , each partially circumferentially extending on a surface of said shank , and at least one second coupling member which is adapted to operably engage with said internal first coupling member of said bushing so as to allow translational but prevent rotational movement of said pin relative to said bushing ; a locking member , having a bore along a third longitudinal axis (D) between a proximal surface and a distal surface, and at least two internal threaded portions , each partially circumferentially extending on a surface of said bore ; wherein, when assembled, said locking member is coaxial with said bushing and said pin and operably coupled to said bushing via a coupling mechanism configured to allow rotational movement of said locking member relative to said bushing about said third longitudinal axis (D) between an adjustment position , where said at least two internal threaded portions of said locking member do not engage with respective said at least two external threaded portions of said shank portion , and a locking position , where said at least two internal threaded portions of said locking member operably engage with said at least two external threaded portions of said shank portion , characterized in that said coupling mechanism is further configured to prevent translational movement along said third longitudinal axis (D) of said locking member relative to said bushing . <EOS>