A device for bone support with improved rotational stability

A bone support fixating device comprising of an hollow intramedullary rod with a smooth anterior medial curve;

• an extended hip screw;
• a set screw;
• an elongate device collectively called the ‘tri-wire’;
• a locking screw 6;
• the intramedullary rod comprising an upper cylindrical proximal portion and lower distal portion;
• the upper end of the proximal portion having a threaded hole through which a threaded set screw passes in order to secure the hip screw towards the bottom of the proximal portion;
• the length of which is approximately ⅓ of the total length of the rod;
• an upwardly inclined hip screw receiving hole to fix the hip screw through the hole with a threaded part of the hip screw entering the hip bone;
• the edges of the inclined hole at the proximal portion having a ‘C shaped surface;
• having a narrow bore formed through the lower part of the proximal portion of the rod and through the complete distal portion of the rod to minimise the use of materials to provide a fixating device which is light;
• an end cap receiving threaded portion through which an end cap travels through;
• the end cap receiving threaded portion having a larger diameter than the set screw receiving female thread;
• having three openings at the proximal end for easy griping;
• the distal end having a conical section with a smoothly rounded end;
• having horizontal oblong slots with smoothly curved surfaces, formed through the distal cross section;
• three equally spaced elongated V-grooves with smoothly formed curved surfaces, formed along the exterior face of the distal portion 8 of the rod resulting in a cloverleaf like cross section;
• a hip screw comprising a hollow shaft having a self-tapping threaded portion at its proximal end and four equally spaced longitudinal grooves at its distal end;
• the grooves having variable heights at different points to aid in dynamisation;
• provided with a narrow longitudinal bore from one end of the screw to save on materials and weight;
• having two co-axial bores;
• provided with a substantially flat distal end face with a mild chamfering or rounding, in such a manner that any possibility of post-operative perforation of the cortex of the femoral head is minimised;
• the distal end of the hip screw having four cruciate slots and wide threaded bore;
• an end cap at the distal end over the ball of the tri-wire to prevent distal migration of the tri-wire;
• the end cap comprising of a shaft with a hole to take the ball of the elongate device in such a manner that the elongate device is extractable;
• the end cap further comprising of a hexagonal head and a threaded portion
• with a step down at the end, easing the entry into the distal thread bore in the hip screw, the hip screw being located within the inclined fixing hole;
• the set screw being located within the threaded bore in such a manner that the smoothly rounded lower end of the set screw is located within one of the four grooves of the proximal end of the hip screw;
• ensuring that the fixating device is fitted to a patient with the hip screw located in the ideal position with respect to the fixing hole;
• the set screw comprising of a solid shaft having a threaded upper end and smoothly rounded ball-nose lower end, there being a hexagonal hole formed through the top face of the shaft to receive an Allen key;
• the locking screw comprising a threaded shaft portion, an enlarged head portion with a hexagonal hole formed through the top face to receive an Allen key and a self-tapping threaded end;
• being long enough such that the head projects outside the shaft of the femur and the self tapping portion cuts a path into the opposing wall of the femur;
• the elongate device is constructed by welding together three stainless steel wires of equal length with rounded or chamfered tips;
• the said wires are pre-sprung, flared and strong;
• comprising of a rod having three holes into which the stainless steel wires are inserted and welded, brazed, soldered, crimped or press-fit;
• the said rod consisting of an enlarged head, a ball-ended tip with a flat milled for easy manipulation as the axis of the ball is directly on the longitudinal axis of the rod, thereby at the centre of the axis of the elongate device;
• being positioned to move through the three tear drop slots in the hip screw;
• in such a manner as to enable these projections to penetrate the bone surrounding the leading end of the bone support to prevent rotation;
• the nail end cap comprising of a solid shaft, threaded portion, an enlarged head flat top surface and an Allen key receiving hexagonal hole, being secured to the intramedullary rod through the threaded hole;
• the projections being guided out of the elongated tear drop holes on the hip screw;
• the elongated tear drop holes being placed on a tapered neck at a forward angle on the tapered neck of the hip screw with a wedge shaped leading edge;
• the tips of the wires moving along the rod in the direction of the hip screw;
• the wedge shaped leading edge bringing about the guiding;
• the back edge of the wedge also angled to enable minimal stress concentration at pivot point of the wires with respect to the back edge;
• the length of each slot proportioned in such a manner as to provide a greater constraint to each of the wires as they emerge from the rod to engage the bone;
• providing maximum control over movement between wire and the hip-screw, resulting
• in faster bone healing;
• the tri-wire not only stablises the intertrochanteric fractures but also maintains the rotational stability of the intracapsular fractures of the neck of femur, widening the indication to the intracapsular fractures by closed intrameduallry method.