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EP-4039232-B1 - MODULAR ARTIFICIAL KNEE SYSTEM

EP4039232B1EP 4039232 B1EP4039232 B1EP 4039232B1EP-4039232-B1

Inventors

  • Jonathan P., Garino

Dates

Publication Date
20260506
Application Date
20211115

Claims (7)

  1. A modular knee joint prosthesis (700, 800) configured to move between an extended position and a flexion position, the modular knee joint prosthesis (700, 800) comprising: a femoral component (10, 702) configured to be mounted to a femur, the femoral component (10, 702) having a first cutout (712, 723) or opening (12) in a central region thereof; a femoral insert (705, 805) removably mounted within said first cutout (712, 723) or opening (12); a tibial component (704) configured to (i) be mounted either directly or indirectly to a tibia, and (ii) engage the femoral component (10, 702), the tibial component (704) having a second cutout (712, 723) or opening (12) in a central region thereof, a tibial insert (706, 806) removably mounted within said second cutout (712, 723) or opening (12), characterized in that a femoral gear (734, 834) is disposed on the femoral insert (705, 805) and a tibial gear is disposed on the tibial insert (706, 806), wherein the femoral and tibial gears are configured to be meshed together.
  2. The modular knee joint prosthesis of claim 1, wherein the femoral and tibial gears are configured to be meshed together in both the extended and flexion positions.
  3. The modular knee joint prosthesis of claim 1, wherein the femoral and tibial gears have gear teeth (734, 752).
  4. The modular knee joint prosthesis of claim 1, wherein at least one of the gears follows a helical trajectory to cause movement of the tibial component (702) (704) in either a medial or lateral direction as the knee joint prosthesis (700, 800) is moved to the extended position.
  5. The modular knee joint prosthesis of claim 1, wherein the tibial component (704) comprises an articular insert (22), and the second cutout (712, 723) or opening (12) is formed in the articular insert (22), and wherein the articular insert (22) is configured to be sandwiched between the femoral component (10, 702) and a tibial baseplate (16) that is mounted directly to the tibia.
  6. A kit comprising the modular knee joint prosthesis of claim 1 and further comprising at least two of the femoral inserts (705, 805) having different geometries, and at least two of the tibial inserts (706, 806) having different geometries.
  7. The modular knee joint prosthesis of claim 1, wherein the femoral insert (705, 805) is removably mounted within the first cutout (712, 723) or opening (12) of the femoral component (10, 702) by a rail and slot engagement, and the tibial insert (706, 806) is removably mounted within the second cutout (712, 723) or opening (12) of the tibial component (704) by a sliding rail and slot engagement.

Description

FIELD OF THE INVENTION This invention relates generally to artificial knee prostheses used for Total Knee Replacement (TKR), and more particularly, to a knee joint prosthesis having an artificial anterior cruciate ligament (ACL) and/or posterior cruciate ligament (PCL). BACKGROUND OF THE INVENTION As is described in U.S. Patent App. Pub. No. 2017/0252173 to Garino, prosthetic knees generally include three main components, a femoral component (FIGs. 1A and 1B), which is attached to the distal end of the femur, a tibial baseplate (FIGs. 2A and 2B), which is implanted onto the proximal end of the tibia, and an articular tibial insert (FIGs. 3A and 3B), which is mounted onto the tibial baseplate and provides a frictional surface for the femoral component. The components are designed to simulate a joint and the associated mechanics of a human knee throughout the knee's range of motion. The components are generally provided in a variety of shapes with varying dimensions (identified as dimensions A-H and J-T in FIGs. 1A to 3B), so that a physician is able to select the optimal combination of components depending on the specific anatomy of the patient. The size and shape of the knee is dependent on various factors including age, gender, and size of the patient. Therefore, a fairly large inventory of components are generally made available, so that the prosthetic knee may be tailored for the patient. During the course of a routine knee construction with a TKR, the ACL is removed in a vast majority of all cases and depending on the selected TKR design, the patient's PCL is either retained or substituted with some mechanism to replace the lost function of the PCL. Even when the PCL is retained, often a portion of the PCL must be cut or partially cut during surgery to aid in the balancing of the knee replacement. When the PCL is completely removed, the PCL is substituted by a post and cam mechanism. A TKR generally comprises a femoral component 10, a tibial baseplate 16 having a post 18 that is implanted within a bore formed in the tibia, and an articular insert 22 that resides on a top mounting portion 20 of the tibial baseplate 16 for interfacing with the femoral component 10. Articular insert 22 may be either separate from tibial baseplate 16, as shown, or integrated with tibial baseplate 16 into a single component. The articular insert 22 and tibial baseplate 16 may be referred to herein either together or individually as a "tibial component." Referring to FIGs. 1A, 1B, 3A, and 3B, an illustration of a typical design of a post and cam mechanism is provided. An articular insert 22 includes an extension 24 that protrudes into an opening 12 of the femoral component 10. A box 11 having upwardly projecting walls is formed on the interior side of the femoral component 10 and includes an interior region that intersects the opening 12. The extension 24 includes a posterior surface 25 that is intended to be in frictional contact with the posterior surface 14 of the opening 12 when the joint is flexed. The resistance generated when the extension 24 bears against the posterior surface 14 of the opening 12 in the femoral component 10 is intended to simulate the resistance that would have been generated by a healthy posterior cruciate ligament (PCL). Cam and post mechanisms have been manufactured that partially replace the function of an ACL by creating a cam surface between the anterior surface of the extension 24 and the anterior surface of the opening 12; however, this solution provides only a partial substitution of an ACL because the anterior side of the extension 24 is at best able to contact the anterior side of the opening only between 0 to 20 degrees of flexion. The lack of an anatomically correct replacement may result in a TKR having reduced functionality as compared to the original knee. This may create difficulties during physical therapy following surgery, as well as limit the patient's ability or desire to participate in physical activity following therapy. Virtually all modern total knee replacements sacrifice the ACL or inadequately substitute it with a crude cam and post mechanism, thus leaving the reconstructed knee with kinematics similar to that of an ACL-deficient knee. Normal knee kinematics therefore remain elusive. In addition, the lack of proper interplay between an ACL and PCL (which together drive normal knee kinematics) leaves the TKR reconstruction short of producing a relatively normal knee for the patient. Given the complexity of the mechanics of a knee joint and the difficulty for patients to adjust to an artificial knee after surgery, an anatomically correct knee replacement system is needed that more accurately simulates the resilience and support formerly provided by the removed ligaments. In order to provide a more anatomically correct TKR, prosthesis embodiments that replicate the function provided by both the ACL and PCL are desirable. Referring now to FIG. 4, a healthy human knee is illus