Artificial knee joint prosthesis

Abstract

The invention relates to an artificial knee joint prosthesis which comprises a patella prosthesis and a femur prosthesis, wherein the patella prosthesis is made of metal and is 3-4mm, preferably 3.5mm in thickness; the femur prosthesis is provided with a tackle part which is made of metal; a polyethylene joint surface is arranged on the surface of the tackle part; and the polyethylene joint surface is gradually thickened from a near end to a far end and no gap exists between the polyethylene joint surface and the tackle part. The artificial knee joint has the following advantages: the patella prosthesis is made of metal, so that the wear resisting property is good, the thickness is thin, the patella cut amount is decreased, then the application scope of the existing knee joint prosthesis is enlarged, the postoperative fracture occurrence rate is reduced, benefit is brought to overhauling and the problem of uneven patella stress distribution is solved at the same time; the tackle part of the femur prosthesis is covered by a layer of ultra-high molecular polyethylene joint surface, so that the abrasion is reduced and the 'soft landing' of femur quadriceps tendon is realized; and no gap exists between the polyethylene joint surface and the metal backing and the polyethylene joint surface and the metal backing are integrally pressed and shaped, so that a polyethylene / metal friction surface is not added.

Description

technical field [0001] The invention relates to the technical field of medical devices, in particular to an artificial knee joint prosthesis. Background technique [0002] Total knee arthroplasty (TKA) is currently the most effective way to treat advanced knee joint lesions. At present, the annual number of TKA cases in the United States has reached 500,000, and it is expected to increase to 3 million by 2030; the radiographic and clinical incidence of knee osteoarthritis in my country is significantly higher than that in the West, and the population base is huge. TKA technology is being developed. my country has been developing rapidly and popularizing. [0003] The conventional TKA operation is to make an incision in the affected knee, perform tibial plateau osteotomy, distal femoral osteotomy, and patella osteotomy, remove the diseased articular cartilage, fix it with special bone cement, replace the corresponding tibial prosthesis, Femoral prosthesis and patellar prosth...

AI Technical Summary

Problems solved by technology

At present, the commonly used patella prosthesis in clinical practice is ultra-high molecular polyethylene patella prosthesis, and the femoral prosthesis is a prosthesis made of cobalt-chromium alloy, stainless steel, titanium, titanium alloy or nickel-cobalt alloy. Has the following disadvantages: (1) narrow scope of application

The traditional polyethylene patella prosthesis is designed according to the anatomical characteristics of western human body. The thickness of the patella is mostly 8-10 mm. After the osteotomy, the patella thickness must be greater than 15 mm to ensure a certain bone strength. This requires the initial thickness of the patella to be greater than 23 mm to be suitable for replacement. Female patients It is the main population for knee joint replacement, but the literature reports that the average thickness of the patella in Korean women is 21.2mm, and the average thickness of the patella in my country is 21.8mm. It is difficult to meet the above requirements. Therefore, when many oriental female patients undergo TKA surgery, the doctor has to do the following for the patella: Treatment: do not replace the patella; replace the patella but the bone bed is too thin; replace the patella and retain the normal thickness of the bone bed, but the total thickness of the patella increases. All of the above options can lead to abnormal biomechanical properties of the patella or complications of the patellofemoral joint, affecting postoperative function

(2) High incidence of postoperative fractures

The amount of bone cut in the traditional ultra-high molecular weight polyethylene patella prosthesis reaches 8-10 mm, the subchondral bone is completely removed, and the deformation resistance of the medial cancellous bone surface of the patella is significantly smaller than that of the lateral (Young's modulus of the medial and lateral bone surfaces of the patella). 2.6GPa and 3.7GPa respectively), the deformation and tension of the inner side of the patella are significantly greater than that of the outer side, which can easily lead to patella fracture and anterior knee pain

(3) Not conducive to renovation

When the patella prosthesis becomes loose and worn, it needs to be revised. If the traditional patella polyethylene prosthesis is used, about 1 / 3 of the patella bone volume has been resected during the initial replacement, and part of the bone is taken away when the prosthesis and bone cement are removed during the revision. If there is a large bone defect, or even only a thin bone shell, the common treatment methods include bone grafting, bone cement filling, using a prosthesis with a metal reinforcing block, and resection of the patella. It is difficult to restore the normal thickness and strength of the patella. Prone to poor postoperative function and serious complications, or even surgical failure

(4) The stress distribution of the patella is uneven, and the patella of polyethylene is easy to wear

Therefore, there is an urgent need for an artificial knee prosthesis that can replace the articular surface of the patella lesion, retain the bone mass of the patella to a great extent, and have less wear and tear, but there is no report on this type of prosthesis.

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