Systems and methods for producing osteotomies

#This invention relates to a device and method for producing osteotomies in bones experiencing angular deformities, and in particular osteotomies associated with angular deformities of the femur and tibia.

#Prior art methods for producing osteotomies to correct angular deformity in a bone mass, such as a femur or tibia, generally require making a large open incision around the deformed site and cutting a wedge, at such site, completely across the deformed bone mass, to initially form two bone pieces. Once the cut has been made in the bone mass and the wedge removed, the bone pieces may be realigned and the angle between the two bone pieces adjusted for corrective purposes. However, because of the invasiveness of the surgery, osteotomy procedures often result in undesirable pain and extended period of immobility for the patient.

#In addition to a period of immobility, prior art methods for producing osteotomies have allowed only minimal control of the bone pieces once the bone mass has been divided. For example, as it may be difficult to control the alignment between the two bone pieces of the deformed bone, the correction of the angular deformity may provide clinical results that are unpredictable. Also contributing to the unpredictability of the clinical results is the difficulty in maintaining the bone pieces in approximation after they have been aligned. Moreover, current osteotomy procedures typically involve application of a uniform corrective angle to the bone pieces, regardless of the individual. As individuals vary in height, weight and age, a slight difference in the angle of a deformed bone mass can cause a measurable difference in contact pressure between the articular surfaces of a deformed bone mass and another bone mass (e.g., between a deformed tibia and a femur). A uniform change in the angle of the deformed bone mass for different individuals, therefore, may not result in a sufficient change in the contact pressure between the articular surfaces of the bones, so as to avoid future degenerative problems.

#FIGS. 1A-D illustrate an angularly deformed femur having a plurality of holes formed in accordance with embodiments of the present invention, and having subcutaneously insertable pins situated within the holes.

#FIGS. 2A-D illustrate a separating device for use in the formation of the holes illustrated in FIGS. 1A-D.

#FIGS. 3A-D correspond to FIGS. 1A-D respectively and further showing a support structure positioned along the anterior surface of the femur.

#A preferred embodiment of the invention herein provides a device and method for producing minimally invasive osteotomies in and about the knee. In accordance with this embodiment, an osteotomy permits accurate, precise and controllable correction of angular deformities in bones about the knee, such that the amount of trauma typically associated with osteotomy is lessened. In order to provide an overall understanding of the present invention, the embodiments of the method of the invention will be discussed with reference to the embodiments of the devices of the invention. However, it will be understood by persons of ordinary skill in the art that embodiments of the invention are applicable to the production of osteotomies of other bones within the body.

#There are two common types of angular deformities usually associated with the femur and tibia, valgus deformity and varus deformity. In either of these conditions, the angular deformity causes a deviation in the amount of contact pressure produced within the intra-articular space between the femur and the tibia, leading to degeneration of the knee joint. In general, valgus deformity, otherwise known as knock-kneed deformity, can be corrected by performing a femoral osteotomy to reduce the relatively high contact pressure between the lateral femoral condyle and the lateral tibial plateau, and increasing the relatively low contact pressure between the femoral medial condyle and the medial tibial plateau. Varus deformity, otherwise known as bow-legged deformity, on the other hand, can be corrected by performing a tibial osteotomy to reduce the relatively high contact pressure between the medial tibial plateau and the medial femoral condyle, and increasing the relatively low contact pressure between the lateral tibial plateau and the lateral femoral condyle.

#With reference now to femoral osteotomy, FIGS. 1A-D illustrate a femur 10 having an angular deformity 11 near its patellar surface 16. In FIG. 1A, sets of holes 12 and 14 are shown formed on the anterior surface of the femur 10 relative to the angular deformity 11. Holes 12 are formed near an end adjacent the patellar surface 16 and substantially parallel to the medial and lateral border of the patella 18. Holes 14, on the other hand, are formed toward an opposite end of the femur 10 relative to the deformity 11 and away from holes 12. Holes 12 and 14 establish sites at which subcutaneously insertable pins 19 may be placed for subsequent attachment of a femur support structure necessary for producing an osteotomy in accordance with an embodiment of the present invention. In a preferred embodiment, FIG. 1C shows one hole 12 and one hole 14 formed on the lateral surface of the femur 10. Hole 12 is formed toward the patellar surface 16 and is positioned substantially in the middle of femoral anterior-posterior diameter A-P. Hole 14, on the other hand, is positioned distal to hole 12 and sufficiently clear of an osteotomy site to be formed, so as not to interfere therewith. The use of a single hole, rather than a set of holes, may be desirable as there is less stripping and thus less damage to the soft tissue surrounding the femur 10.