An internal fixation device for use in a transverse surgical neck fracture of the humerus to cross fix a fracture line, the internal fixation device comprising a guide plate and a single screw;
- wherein the guide plate comprises
- a generally rectangular shaped low profile guide plate for abutting against the diaphysis cortex of the humerus on one side of the fracture and having a front side, a back side and a bore therethrough located adjacent to one end of the low profile guide plate;
- a short barrel portion having a distal end with an opening, a proximal end with an opposite opening, an inner sidewall, and an inner flange adjacent to the distal end, the inner sidewall defining a passage extending from the distal end opening to the proximal end opening, the internal diameter of the distal end opening being less than the internal diameter of the passage of the inner sidewall of the barrel portion, the length of the barrel portion being sufficiently short so as not to cross the fracture line and also to rest a sufficient distance from the fracture line to leave a bone mass between the fracture line and the distal end of the short barrel portion;
- said proximal end of said barrel portion integrally attached to said front side of said low profile guide plate at an inclined angle between 155.degree. to 170.degree. such that said passage is communicating with said bore of said low profile guide plate, said short barrel portion for adapting within said diaphysis cortex of the humerus such that said front side of said low profile guide plate is placed against the diaphysis cortex of the humerus;
- wherein the single screw is
- an elongated lag screw for internally cross fixing the fracture line and settling in the depth of the epiphysis and having a distal threaded portion, a middle shaft portion, and a proximal portion, the proximal portion having a proximal shoulder flange and a proximal head with means for receiving a driving tool in its top end, the diameter of the middle shaft portion being less than the diameter of the proximal shoulder flange, and the diameter of the shoulder flange being less the diameter of the proximal head;
- and
- said lag screw being slidably received within said passage of said barrel portion and extending out of said barrel portion for cross fixing the fracture line of said diaphysis cortex of the humerus with said distal threaded portion of said lag screw being located within the depth of the epiphysis, said proximal shoulder flange of said lag screw being press-fitted within said distal end opening of said barrel portion such that said proximal head of said lag screw is contacting said inner flange of said inner sidewall of said short barrel portion and rests within said barrel portion for preventing said proximal head from extending out of said barrel portion when said low profile guide plate is compressed against said diaphysis cortex of the humerus, and said low profile guide plate adapted for being fixed to the diaphysis cortex of the humerus solely by said lag screw and dissipates all of the compression forces of the internal fixation device;
- whereby said low profile guide plate dissipates all of the compression forces of said internal fixation device that are applied against said diaphysis codex of the humerus, and thereby said diaphysis codex of the humerus remains healthy and intact.