Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2001-02-01
2003-05-13
Bennett, Henry (Department: 3743)
Surgery
Instruments
Orthopedic instrumentation
C606S065000, C606S066000, C606S075000
Reexamination Certificate
active
06562042
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a medical device used to repair intertrochanteric fractures of the femur and a method for inserting and using the same.
2. Description of the Currently Available Technology
Current implants for the treatment of intertrochanteric (“IT”) fractures consist of a variety of devices which are distinguished by three cardinal features—two of which are generally mechanical in nature and the third of which relates to the surgical procedure for implantation of the devices in a patient.
The femur is generally comprised of its head, which is ball-shaped and fits into the hip socket, its neck which is generally cylindrical in shape and extends from the head of the femur towards the shaft of the femur, the body or shaft of the femur which forms the major longitudinal axis of the femur, and an intermediate region which connects the shaft of the femur with the neck of the femur. This intermediate region is the trochanteric region and, very generally speaking, it holds the body of the femur and the neck of the femur at an angle of about 130 degrees relative to one another. This angle, often called the neck/shaft angle is not always precisely a 130 degree angle, but may vary considerably in each animal or human having a femur, but will generally be referred to hereinafter as a 130 degree angle for discussion purposes. Fractures in the trochanteric region of the femur are generally termed intertrochanteric or “IT” fractures.
All orthopedic implants for the treatment of IT fractures of the femur must operate to hold the head of the femur at the above-described generally 130 degree angle relative to the body of the femur during healing of the fracture of the trochanteric and/or neck of the femur. All such orthopedic implants generally consist of three main elements. The first is a hip implant, also commonly referred to as a hip screw, which is screwed at one end into the head of the femur and extends therefrom to the body of the femur. The second is a stable platform affixed in some manner to the body of the femur. The third is a mechanism for affixing the hip screw and the stable platform to one another in order to hold the body of the femur and the head of the femur at the above-described generally 130 degree angle to one another while the fracture or fractures in the intervening region heals.
The three cardinal features which differentiate the presently available orthopedic implants are: 1) the type of stable platform employed by the implant (e.g., intramedullary or extramedullary); 2) the type of connection between the hip screw and the stable platform (e.g., rigid, dynamic or static plus dynamic); and 3) the surgical procedure, and more particularly, whether it is the hip screw or the stable platform that must be first implanted in the patient.
With regard to the first cardinal feature, there are two types of stable platforms which can be affixed or otherwise associated with the body of the femur—intramedullary and extramedullary. Extramedullary platforms typically employ one or more plates affixed to the outside of the body of the femur with screws which extend generally transverse to the femur's longitudinal axis into the body of the femur to attach the plate to the body of the femur. The hip screw and plate are affixed to one another to hold the head of the femur and the body of the femur at the above-described generally 130 degree angle during the healing process. Extramedullary platforms of this type are particularly useful for nondisplaced or minimally displaced IT fractures.
Intramedullary platforms typically employ an intramedullary nail (IM nail) which is generally a metal rod or tube which is inserted from the top of the femur through the trochanteric region into the hollow core of the body of the femur (known as the intramedullary cavity). The intramedullary nail extends along a portion of the body of the femur, and may extend from the trochanteric region of the femur through nearly all of the body of the femur. The intramedullary nail is generally affixed at its end opposite the end implanted in the trochanteric region (e.g., that portion of the intramedullary nail nearest the patella) to the shaft of the femur with screws inserted transverse to the longitudinal axis of the shaft of the femur through the femur and through the intramedullary nail. The hip screw is positioned generally transverse to the intramedullary nail's longitudinal axis into the head of the femur. The intramedullary nail and hip screw are affixed to one another as explained below, to prevent relative motion in order to provide the stabilization of the body of the femur and the head of the femur at the above described generally 130 degree angle during the healing process.
As between intramedullary platforms and extramedullary platforms, intramedullary platforms are generally more desirable because the moment arm between the head of the femur and the intramedullary nail is less than that of the moment arm of extramedullary platforms where the moment arm extends between the head of the femur and the extramedullary plate attached to the outside of the femur. Thus, the moment arm mechanical forces on the intramedullary implant are lower and it is therefore less likely to experience a mechanical failure. Intramedullary platforms are also desirable because they generally involve a less invasive surgical exposure for implantation. In other words, rather than having to make a surgical incision along a substantial portion of the length of the femur sufficient to permit the surgeon to insert the plate of the extramedullary platform and attach it to the outside of the body of the femur, the intramedullary platform permits the surgeon to simply make a small incision at the top of the femur to insert the intramedullary nail and a small incision on the side of the femur to insert the hip screw.
With regard to the second cardinal feature, the type of connection between the hip screw and the stable platform differentiates presently available orthopedic implants. Such connections may be rigid, dynamic or “static plus dynamic.”
Bone compression occurs during the healing process. Bone compression or simply compression, refers here to the process in which bones held together during healing collapse into one another during the healing process to provide a smaller overall dimension than that provided when the fragments were first placed contiguous to one another during the surgery conducted to set the broken bone. Uncontrolled compression is undesirable, but controlled compression is desirable as it permits the fractured bone to heal along desired or required compression paths.
Rigid connections permit no movement in any direction between the stable platform and the hip screw, and are therefor unable to accommodate bone compression that may occur during the healing process.
Dynamic connections permit some movement between the stable platform and the hip screw during the healing process. More particularly, where for example the femur is a human femur and the patient is viewed from a standing position, dynamic connections permit the stable platform to move closer to or further away from the head of the femur along the longitudinal axis of the hip screw, but do not permit vertical movement of the stable platform relative to the longitudinal axis of the hip screw. Dynamic connections can accommodate bone compression, and allow the hip screw to guide the fracture to its most stable position during the healing process without further surgical intervention, but do not provide a post-operative compressive force along the longitudinal axis of the hip screw to urge the stable platform towards the head of the femur, which may be desirable to stabilize the fracture.
Static plus dynamic compression devices also provide such guidance, but permit the surgeon to stabilize the fracture intraoperatively by applying compression forces on the fracture and then allow further dynamic compression during the healing phase.
With regard to the third cardinal feat
Bennett Henry
DKW Law Group, PC
Ferko Kathryn
Schnell Terry L.
LandOfFree
Orthopedic implant used to repair intertrochanteric... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Orthopedic implant used to repair intertrochanteric..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Orthopedic implant used to repair intertrochanteric... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3011628