REINFORCED ARTICULATING HIP JOINT SPACER WITH ADJUSTABLE OFFSET AND METHOD OF ITS MANUFACTURING Russian patent published in 2024 - IPC A61F2/32 A61F2/36 

FIELD: medicine.

SUBSTANCE: group of inventions relates to medicine. Articulating hip spacer with adjustable offset is made of bone cement with the addition of an antibiotic, comprising a head, a leg of the femoral component with a neck for the head, self-tapping screw for connection with head is made with head and channel for K-wire. Head is made in the form of a hemisphere changing into a cylindrical neck with a seat channel for the neck of the leg of the femoral component. Through canal for the screw to communicate with the head is made in the centre of the neck of the leg of the femoral component. Self-tapping screw for connection with the head has the possibility of changing the offset length during rotation along the axis of the neck of the leg of the femoral component. Leg of the femoral component is made with a reinforced K-wire, which is bent in half and is located along the axis of the leg of the femoral component, and in the upper third in the area of the self-tapping screw location for connection with the head it has a U-shaped bend, which protrudes in the upper third of the leg, forming a loop for the possibility of the spacer removal. Width of "U" -shaped bend is 3 mm more than diameter of head of self-tapping screw for connection with head. Method of making said articulating hip spacer with adjustable offset is characterized by the fact that the sizes of the endoprosthesis components are determined based on the CT-scanned pelvic tomography data with the femoral bone capture, then, using the software, fitting models of a spacer – a cotyloid component, a head and a leg of the femoral component with a neck for the head – are designed. Canal for a self-tapping screw for connection with a head, made with a head and a channel for a K-wire are modelled along the axis of the leg of the femoral component. Its centring, size and thickness are determined. Fitting models are printed on 3D printer. Then, a matrix is made for filling silicone moulds of the spacer so that gap of 5 mm remains between the wall of the matrix and the fitting model of the spacer. For the fitting model of the leg with a neck for the head, through channels with diameter of 2 mm are formed for the K-wires, and a filling channel is formed in the end part of the fitting model. Further, the fitting model is placed in the matrix. Straight K-wire is installed in the fitting model along the neck axis, and along the axis of the leg with a neck for the head a K-wire is installed, which is bent in half and is located along the axis of the leg of the spacer with a neck for the head, and in the upper third, in the area of the self-tapping screw for communication with the head, has a protruding U-shaped bend in the upper third of leg with a neck for the head, forming a loop for the possibility of removing the spacer, width of bend is 3 mm greater than the diameter of the head of the self-tapping screw for communication with the head. Whole structure is filled with medical silicone. After the silicone hardens, the fitting model with wires is removed, the matrix with the silicone shell and the fitting models are sterilized. In the operating room, after the skin incision with excision of the postoperative old scar, the endoprosthesis is approached and dislocated, then components of the endoprosthesis are removed, bone and soft tissues are debrided, a proximal femur bed is prepared with rasps, and a joint area is sanitized with antiseptic solutions. To make an articulating spacer, cement is mixed with an antibiotic, poured into silicone moulds of an acetabular component, a head and legs with a neck for the head. To make an acetabular component and a spacer head, cement with an antibiotic is introduced into the silicone moulds through a filling channel with the help of a syringe, and after polymerisation the cement is removed from the mould and excess silicone is removed. Viscous mass of bone cement is placed in the cotyloid cavity so that it completely fills the cotyloid cavity with all defects. Acetabular component of the spacer is inserted into the cement paste, compression is performed, and the excess cement is removed. For a leg with a neck for the head, one K-wire is bent in half, a U-shaped bend is formed in the area of the upper one-third and installed in a silicone mould channel located along the axis of the leg with a neck for the head, the second K-wire is installed in the channel under the self-tapping screw for communication with the head, which passes along the centre of the leg neck axis. After polymerisation of the cement, the silicone mould is disassembled, the leg with a neck for the head is removed and the wire located in the neck of the leg is removed. Bone cement with an antibiotic is used to treat an upper part of leg with a neck for the head and to be inserted into a femoral canal. After polymerisation of the cement, a K-wire is inserted into the canal from the neck of the leg, and the wire is inserted retrograde through the lateral cortical layer of the femur. After that, the self-tapping screw for connection with the head is carried out along the axis of the neck of the leg along its entire length, guided by the K-wire, having previously drilled a channel for the diameter of the head of the self-tapping screw. Loop for the possibility of removing the spacer, which is located in the upper part of the leg, is bent and covered with cement. Further, cement is applied into the seating channel of the head of the spacer, the head is installed on the neck of the leg of the spacer, hip reduction is performed and offset length is adjusted by rotation of self-tapping screw for connection with head along axis of neck of femoral component and change of head protrusion position, after polymerisation of the cement, the wound is drained and closed in layers.

EFFECT: inventions provide possibility of adjustment of femoral offset and length of lower extremity, which provides optimal tension of muscles in area of hip joint and promotes scar constriction, and also provides non-traumatic removal of spacer with maximum preservation of bone tissue.

2 cl, 6 dwg, 1 ex