RU170830U1 - Pins to strengthen the bowls of the acetabular component of the hip endoprosthesis - Google Patents

Abstract

The utility model relates to medicine in the field of traumatology, orthopedics and rheumatology, namely, to the device of the hip joint endoprosthesis. The pins for strengthening the bowl of the acetabular component of the hip joint prosthesis consist of a central cylindrical part with helical grooves running at an angle of 30 ° to the distal part of the pin, the width of the helical grooves is 2 mm and a depth of 1 mm, the distal part of the pin 8 mm long has a conical shape with a flat ( blunt) surface at the end, and the proximal part of the pin is made in the form of a cylindrical head with a diameter of 5-6 mm, a nanostructured calcium phosphate coating 60-70 μm thick is applied to the surface of the pins. The proposed utility model provides the reliability of primary and secondary fixation of the hip joint prosthesis.

Description

The utility model relates to medicine in the field of traumatology, orthopedics and rheumatology, namely, to the device of the hip joint endoprosthesis.

In case of fractures of the femoral neck, the use of a hip joint endoprosthesis is widely used. Fractures of the femoral neck are severe and frequent damage to the musculoskeletal system in the elderly and senile, arising against the background of osteoporosis. The mortality rate of elderly and senile patients in the first 6 months after injury reaches 20%. The frequency of fractures of the femoral neck in this category of patients over the past 65 years worldwide has increased from 135.5 to 612.7 per 100 thousand population [MG Kakabadze Fractures of the femoral neck: arthroplasty in the acute period. // Abstract. dis. Cand. honey. Sciences., Moscow, 2005; Yezhov I.Yu. et al. Total endoprosthetics for fractures and false joints of the femoral neck // Endoprosthetics in Russia. Issue 5. - Kazan, 2009. - S. 101-107]. Among patients who have used traditional conservative methods, up to 80% die during the first year of life after an injury [Klyuchevsky V.V. et al. Endoprosthetics for hip fractures // Bulletin of Traumatology and Orthopedics. - 2009. - N3. - S. 21-25].

According to the WHO, mortality among elderly and senile patients with a fracture of the proximal femur reaches 12-15%. In the conservative treatment of fractures, i.e. with prolonged bed rest, mortality reaches 25-40% [Voitovich A.V. Surgical treatment of patients with fractures of the proximal femur in the system of medical rehabilitation. // Abstract. dis. Doct. honey. sciences. S - Pb. 1994. - 24 p.].

There are many endoprostheses of the hip joint, however, the main disadvantage of the proposed endoprostheses is the instability of the fixation of the bowl of the acetabular component.

To strengthen the cup of the acetabular component of the hip joint endoprosthesis, helical ribs are provided in the cups [Patent RU No. 2092132 C1 of 10/21/1997], holes for clamps are made in the cup [Patent RU No. 2083184 C1 of 10/21/1997], the cup is made of corundum ceramic with porous coating [Patent RU No. 2120257 C1 of 10.20.1998]. Meridionally directed grooves, slots are formed on the bowl [Patent RU No. 2183441 C2 06/20/2002; Patent RU No. 2071299 of January 10, 1997], grooves with an annular chamfer are performed on a cylindrical bowl [Patent RU No. 229179 C2 of 08.20.2005], the cups are fixed with bolts, spongy screws [Patent RU No. 2265420 C1 of 12/10/2005; RU patent No. 2303050 from 2007] Through holes with threaded threads are formed in the bowls [RU patent No. 2297203 C2 dated 04/20/2007]. Pointed spikes are made on the outer surface of the metal bowl [Patent RU No. 2040228 C2 of 03/27/2003], use the transverse corrugated surface of the bowl [Patent RU No. 2299707 C2 of 05/27/2007]. The bowl is equipped with teeth, a shoulder having a thread [Patent RU No. 2040228 C1 of 07.25.1995; Patent RU No. 2040227 C1 of 07.25.1995].

The closest technical solution we have taken as a prototype is an acetabular endoprosthesis having inserts (pins) made of porous titanium nickelide [Patent RU No. 66190 of 09/10/2007].

The disadvantage of the proposed device is the instability of the fixation of the bowl in the acetabulum, since there are no osseointegrative properties of the structure, namely, the osseointegrative connection of bone structures with the implanted structure is not formed. As a result of the progression of osteopenic syndrome, this drawback leads to pathological mobility of the endoprosthesis.

The task of constructing pins to strengthen the bowl of the acetabular component of the hip joint implant is to create a simple device that provides a strong and reliable fixation of the acetabular endoprosthesis not only at the osteogenesis stage, but also at the stages of cyclic remodeling due to the formation of osseointegrative connection of bone structures with implantable design.

The technical result is achieved by the fact that the pins have helical grooves, which ensure that the pins are screwed into the bone tissue and the endoprosthesis is fixed in the acetabulum, and the nanostructured calcium phosphate coating provides an osteointegrative connection of the bone structures with the implanted structure.

The technical result of the proposed device is achieved by the fact that according to the technical solution, the pins for strengthening the bowl of the acetabular component of the hip joint prosthesis consist of a central cylindrical part with helical grooves running at an angle of 30 ° to the distal part of the pin, the width of the helical grooves is 2 mm and the depth is 1 mm, the distal part of the pin 8 mm long has a conical shape with a flat (blunt) surface at the end, and the proximal part of the pin is made in the form of a cylindrical head with a diameter of 5-6 mm, on The surface of the pins is coated with a nanostructured calcium phosphate coating 60-70 μm thick.

The proposed utility model is illustrated by graphic material. The figure 1 shows a top view of the cup of the hip joint endoprosthesis, where 1 is the pin, 3 is the commercially available hip joint endoprosthesis cup, 4 is the plug of the insertion hole of the endoprosthesis cup; 5 - holes for pins.

The figure 2 shows the pin in the bowl of the hip joint endoprosthesis, where 1 is the pin, 2 is the central cylindrical part of the pin with a helical groove, 3 is the commercially available bowl of the hip joint prosthesis, 5 is the hole for the pin in the commercially available bowl of the hip joint prosthesis.

The figure 3 shows the pin, where 1 is the pin, 2 is the central cylindrical part of the pin with a helical groove, 6 is the cylindrical head of the pin.

The proposed device is used as follows: after access to the hip joint, dislocation and osteotomy of the femoral neck, the remnants of the capsule with ligaments are removed. Then, spherical cutters, starting from the smallest diameter, develop the acetabulum, form the bone bed, removing the remnants of the cartilage tissue to the subchondral layer. The subchondral layer is treated only to a bleeding surface, removing only the layer in a state of aseptic necrosis. The cavity is processed to the required size of the metal bowl. Then the bowl is driven into the acetabulum, while observing the necessary angles of inclination and anversion. When clogging the cup, truncated half-cylinders get bone chips scraped from the surface of the bone bed. Visual control of the position of the surface of the bowl relative to the bone bed is carried out through the viewing windows. Pins are installed in the viewing windows of the acetabular component of the endoprosthesis. Pins through the inspection openings of a standard bowl of the hip joint endoprosthesis are driven into bone tissue. The presence of helical grooves in the cylindrical central part of the pins provides helical progression of the pins in the bone tissue.

The positive properties of the pins are expressed due to additional helical grooves with high porosity and a nanostructured calcium phosphate coating to enhance the osseointegrative properties of the device.

Clinical example

Patient K., 75 years old. Received complaints of pain in the right hip joint when walking and limiting movements. Movement in the joint: flexion of 45 degrees, abduction of 20 degrees. Relative shortening of the right lower limb by 3.5 cm. On radiographs of the right hip joint, signs of coxarthrosis of the III st. On the basis of clinical and radiological data, the diagnosis was made: Right-sided coxarthrosis III art. Adjacent contracture of the right hip joint. The tactics of further treatment are determined: The need for total endoprosthetics of the right hip joint.

The proposed device was used as follows: After access to the hip joint, dislocation and osteotomy of the femoral neck, the remains of the capsule with ligaments were removed. Then, spherical cutters, starting with the smallest diameter, developed the acetabulum, formed a bone bed, removing the remnants of cartilage tissue to the subchondral layer. The subchondral layer was treated only to a bleeding surface, removing only the layer in a state of aseptic necrosis. The cavity was processed to the required size of the metal bowl. Then the bowl was hammered into the acetabulum, while observing the necessary angles of inclination and anversion. When clogging the bowl, truncated half-cylinders got bone chips scraped from the surface of the bone bed. Visual control of the position of the surface of the bowl relative to the bone bed is carried out through the viewing windows. Pins were installed in the viewing windows of the acetabular component of the endoprosthesis and hammered into the bone tissue. The helical progress of the pins in the bone tissue provides a reliable fastening of the bowl of the acetabular component of the hip joint prosthesis. After installing the bowl in the inner cavity, a polymer insert is inserted. After the operation, the wound was drained and sutured in layers. The patient was discharged on the 12th day in a satisfactory condition for outpatient treatment in the clinic at the place of residence under the supervision of a traumatologist.

Remote observation results: joint flexion increased to 90 °, and abduction up to 45 °. Relative shortening of the left lower limb after surgical treatment was not noted.

The given clinical example demonstrates the necessity of using this device when installing a hip joint implant. Reliability of the primary fixation of the bowl of the hip joint endoprosthesis is ensured due to the tight fit of the cup to the bone bed and clogging of pins with a helical groove through the inspection openings of the endoprosthesis. Reliable secondary fixation of the bowl is achieved due to increased osseointegration of the peri-implantation zone around the pins with a nanostructured calcium phosphate coating with osteoinductive and osteoconductive properties.

The proposed utility model was introduced on the basis of the Design Bureau No. 2 of Tyumen and used in operations for total hip arthroplasty. Conducted 4 operations with a positive effect.

Claims (1)

Pins for strengthening the bowls of the acetabular component of the hip joint implant containing inserts (pins), characterized in that the pins consist of a central cylindrical part with helical grooves running at an angle of 30 ° to the distal part of the pin, the width of the helical grooves is 2 mm and the depth is 1 mm, the distal part of the pin 8 mm long has a conical shape with a flat (blunt) surface at the end, and the proximal part of the pin is made in the form of a cylindrical head with a diameter of 5-6 mm, nanostructured is applied to the surface of the pins calcium-phosphate coating of 60-70 microns thick.

Images