Surgery – Instruments – Orthopedic instrumentation
Patent
1995-06-30
1997-04-01
Buiz, Michael Powell
Surgery
Instruments
Orthopedic instrumentation
606 96, 606 89, A61B 1758, A61B 1760
Patent
active
056161476
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to means to safely determine the mutual positions of a femur and an ilium in hip surgery to be able to correctly make a surgical replacement of pathologic components.
More exactly the invention relates to means for hip joint surgery giving a very high grade of certainty in obtaining a correct length of the leg, the right off-set regarding ithium and the correct joint hook of the prosthesis.
In hip joint surgery it is of vital importance to have the surgical replacement components fixed in mutual positions corresponding to the original positions of the joint components (femur head of the femur and the acetabulum of the ilium) provided that an adjustment of the length of the leg and/or the joint hook is not to be made in connection to the surgery. Thus the surgically replaced prothesis of the femur head must have essentially the same extension in the length direction in a determined angular setting to the extension of the femur as was the case for the original femur heads, and at the same time as the position of the acetabulum of the hip must allow a correct bending action in a normal position of the pelvis. The femur and the new prothesical femur head and the acetabulum in the hip are exposed to stress cycles (pressure and bending stresses) which, if concentrated on some components of the natural bone, may involve a risk of destruction of the bone. In a total hip replacement it is also important that a correct length of the leg and a correct off-set are obtained to avoid a defective walking which easily can inflict damages on other joints and muscle attachments, especially in the back of the body. Thus it is of vital importance that concentrations of stresses are evenly distributed as possible and that the position of the body after the surgery not have to be changed to compensate for incorrectly implanted prothesis components. This even distribution of stresses and the original way of moving and walking after an operation is facilitated if the implanted prothesis components will take positions that essentially correspond to the original and correctly acting, but pathologic hip.
Since hip surgery is likely and most often done to elderly people it is important that learnt and automated movement patterns of the legs can be kept unchanged as far as possible after surgery. It is well known that it is very difficult and sometimes impossible for elderly people to change a moving, pattern once learnt.
The object of the present invention is to obtain a technique making it possible to attach joint protheses in exact positions to avoid stress concentrations and destruction of the bone and to make it easier for the patient to walk again without having to adapt his/hers walking an incorrectly implanted hip joint prothesis.
The invention will now be described in connection with the drawings showing one embodiment by way of example, where
FIG. 1A is a side view of a femur head in an initial position and onto which first orientation means is attached;
FIG. 1B is an enlarged view from below of a part of the first orientation means showing a possibility for adjustment;
FIG. 2 is a diagrammatic view of an attachment of the other attachment means onto the pelvis;
FIG. 3 shows the other orientation means being attached at the pelvis and the control of the mutual parallelism of the orientation means;
FIG. 4 shows the position for determine the distance between the two orientation means;
FIG. 5A shows the femur head and pelvis after removal of the orientation means and just before the replacement of worn joint components;
FIG. 5B shows how a necessary adjustment of the length of the leg can be made prior to removal of the orientation means; and
FIG. 6 shows the final adjustment of the femur and pelvis back to their initial positions prior to the final locking of the femur prosthesis components.
FIG. 1A shows a femur head 1 on a trochanter surface of which a fixing means 2 in the form of a tipped screw just has been struck into the bone with a hammer 3. The screw is in threaded engagement with thread
REFERENCES:
patent: 5122145 (1992-06-01), Fishbane
patent: 5141512 (1992-08-01), Farmer et al.
patent: 5213112 (1993-05-01), Niwa
patent: 5385567 (1995-01-01), Goble
Buiz Michael Powell
Leonardo Mark S.
Meduse Scandinavia AB
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