Patent Application
20090043397
1. Field of the Invention
The present invention relates to a modular femoral head surface replacement, a modular femoral neck stem, and related sleeve, adapter, and osteoconducting rod, which are used to perform total hip replacement.
2. Background Art
In general, as a person grows older, a cartilage of the femoral head is gradually worn out or disappeared, and so, it may result in osteoarthritis of the hip joint or avascular necrosis of the femoral head (hereinafter, referred to as “AVN”) due to an unknown cause. In the above case, at the early stage, various surgical operations may be performed to preserve the femoral head, but finally, total hip arthroplasty (hereinafter, referred to as “THA”) is performed. Recently, the femoral head surface replacement (hereinafter, called “FHSR”), which had failed in the past, has obtained good results through an innovative development of materials of metal. and so, many companies are producing approvals. In the conventional THA, the size of the femoral head, which was 22 mm previously, has been increased gradually to 28 mm and 32 mm, and recently, the femoral head of more than 36 mm has been experimentally developed and used. Such a big femoral head has several merits in that a wide range of motion, low dislocation rate and it is little wearing since it is a metal on metal FHSR than previous polyethylene on metal THA. However, the big femoral head has several disadvantages as cost of manufacturing is very expensive since several kinds of the femoral head must be manufactured and prepared for each patients. However, a modular femoral head system(a surface replacement or a big femoral head) according to the present invention is economical since it is using a modular locking methods without needing to independently manufacture all kinds of the femoral head, and maximizes convenience in use since the big femoral head can be inserted using an invented adapter for connecting a conventional THA or osteoconducting metal rod
Since a conventional THA are composed of a plastic liner in a metal acetabular cup, and a small metal or ceramic femoral head (diameter of head is commonly 28 mm) in the femoral stem. The conventional THA has several problems, such as frequent dislocation because of small femoral head wearing of plastic liner and resulted osteolysis due to abraded plastic microparticles. To treat the AVN, multiple drillings, vascularized bone graft, or rotational osteotomy can be performed in the initial stage of AVN, but finally, the best surgical treatment is to perform total hip replacement after cutting the necrotic femoral head and femoral neck.
Recently, there has been reported that a successful results from femoral head surface replacement by USA and UK. However, the femoral head surface replacement have some complications such a femoral neck fracture and suspicious metal ions accumulation in the organ. For prevention of the femoral neck fracture is not to make a notching of the femoral neck during operation or a valgus fixation of a femoral neck stem is recommended and but there were no proven harmful reports for metal ions accumulation to this time. The conventional THA, which has been performed to patients in Asian people who have the seating life style, namely, mainly seat on the floor, feel inconvenience in performing house affairs and working at work places, and in that a young sportsman, who underwent the surgery of the conventional THA, cannot live as the sportsman again because of narrow range of motion and earlier wearing of polyethylene liner. However, recently, metal on metal FHSR or a big femoral head using THA comes into the spotlight since ballet dancer, baseball player or golfers can keep their positions as sportsmen after undergoing the surgery with a FHSR or total hip replacement.
The total hip replacement, which is the final treatment method of osteoarthritis and AVN of the femoral head, is the most successful treatment to relieve the pain and recover the stability and increase the range of motion. However, as time goes, because of progressive worn-out of a plastic liner, resulted osteolysis in the pelvis and femur by abraded particles, a reduction in a range of motion (96 degree in case of the femoral head of 22 mm, and 103 degree in case of the femoral head of 28 mm) of the hip joint and increased dislocation rate of the hip joint due to a small femoral head and instability. Anyone who managed with conventional THA, showed difficulties in sports activities. A big and hard-bearing femoral head is preferred gradually, and so, a CoCr-alloy or a ceramic femoral head comes into the spotlight. As commonly, simple and fixed-type big femoral heads or femoral head surface replacements are used in the world medical market, but a modular femoral head surface replacement according to the present invention give a convenience and supported to a surgeon to choose a straight or tapered, fluted type stem according to the patients' bone state.
Now is the time to challenge to the market of medical appliances owing to development of metal industry and ceramic technology. The most important point of the surgeon who chooses the implant is the design. The modularity, adapter and sleeve systems are to give a chance to surgeon to correct misdirected located femora stem by using an eccentric femoral neck stem or adapter. The modularity give a forgiveness to surgeon to change the operation methods, the sleeve system gives an initial stability of the femoral stem and the adapter can be used with conventional THA alternatively
The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings, in which:
Reference will be now made in detail to the preferred embodiment of the present invention with reference to the attached drawings so that those skilled in the art can easily understand and reproduce.
As described above, the present invention provides the modular FHSR in stead of the conventional fixed type FHSR, and the modular FHSR according to the present invention can be applied in the conventional THA but also to the big femoral head. The various types of FHSR or modular big femoral head which can be selected according to the patients' conditions. As a related part of the FHSR, the sleeves of various types can be applied according to the degree of avascular necrosis of the femoral head to prevent or support a breakage of the femoral neck or femoral neck stem metal as complications of the FHSR The adapter for mounting the big femoral head is connected with the femoral stem of conventional THA in such a way that an artificial femoral head is attached to the femoral neck without removing a healthy femoral neck differently from the conventional total hip replacement even though avascular necrosis of femoral head occurs. Moreover, according to the present invention, by using the adapter connectable with the osteoconducting rod (or a trabecular metal rod), which can be used in the beginning stage of avascular necrosis of the femoral head, even though the avascular necrosis of the femoral head makes progress, total hip replacement of the mini incision method can be performed without inserting the conventional large femoral stem to the marrow cavity, whereby the present invention is economical since it can reduce a surgical operation period and does not need a great deal of blood transfusions, and allow the patients to walk directly after the surgical operation. Owing to the development of the medical science, stem cells can be used experimentally for revascularization of the dead portion of the femoral head, but the greatest problem is to develop a carrier to transfer the stem cells correctly to an avascular lesion without splitting or falling down. To solve such a problem, the present invention 54 act as a stem cell carrier. This container in which we inserted stem cell like a oral pill in medical drug.
While the present invention has been described with reference to the particular illustrative embodiment, it is not to be restricted by the embodiment but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiment without departing from the scope and spirit of the present invention.
