Hip joint device and method
View Patent ↗A method for implantating a medical device in a hip joint of a patient is provided. The medical device is adapted to be fixated to the pelvic bone of the patient, and comprises an inner and an outer surface, a contacting portion of the inner surface is spherical and adapted to face the center of the hip joint when said medical device is implanted, and said medical device is adapted to receive a caput femur or a prosthetic caput femur having a spherical portion. The medical device comprises at least one extending portion adapted to clasp the caput femur, or prosthetic caput femur, for restraining said caput femur, or prosthetic caput femur in said medical device. The medical device is adapted to release the caput femur or prosthetic caput femur from the medical device when a predetermined strain is placed on the medical device. The ability of the medical device to release the caput femur or prosthetic caput femur from the medical device when a predetermined strain is placed on the medical device reduces the risk that the prosthesis is loosened by an abnormal strain being placed on the hip joint from e.g. the patient falling or making a rapid movement of the hip.
1 . A method for implantation of a medical device in a hip joint of a patient wherein said medical device comprises an inner and an outer surface, having a contact portion of said inner surface being spherical and bowl shaped, and the inner surface facing the center of the hip joint having at least one extending contacting portion wherein said medical device is configured to release a caput femur or prosthetic caput femur from said medical device by deflecting said at least one extending portion when a predetermined strain is placed on said medical device by abnormal movement of the hip joint caused by the patient, said method comprising,
cutting the skin in a hip region of the patient,
dissecting the hip joint,
implanting the medical device in the hip joint of the patient,
fixating the device to a pelvic bone of the patient,
placing the caput femur or the prosthetic replacement therefore having a spherical portion, such that said extending contacting portion of said inner surface is
clasping said spherical portion of said caput femur, or a prosthetic replacement therefore, such that said caput femur, or a prosthetic replacement therefore is restrained in said bowl shaped inner surface.
2 . The method according to claim 1 , wherein the method further comprises:
placing a caput femur or an artificial replacement therefor for contacting towards said inner surface of medical device, said inner surface comprising an equator line being the largest circular circumference of said inner contacting surface,
placing said medical device and passing with said at least one extending portion beyond said equator line, such that the end portion of said contacting portion of said inner surface forms a circular extension line having a parallel smaller circumference than said equator line, the end portion being the most distal portion of the inner surface being in contact with said caput femur or artificial replacement therefore, when said caput femur or artificial replacement therefore is placed symmetrically in said inner surface, and placing a portion of said collum femur or prosthetic replacement therefore between said extension line and said equator line when moving said caput femur or artificial replacement therefore in relation to said inner surface.
3 . The method according to claim 1 ,
wherein the step of implanting said medical device comprises implanting a medical device having at least one of at least one of the following alternatives:
a) the at least one extending portion is extending circumferentially discontinuously along said equator line having a portion of the circumferential distance lacking any extending portion and b) the at least one extending portion is extending with different distal extension in different extending portions or part of such portion of said circumferential extension,
and wherein the step of placing the caput femur or the prosthetic replacement therefor having a spherical portion comprises placing a prosthetic caput femur being ball shaped at least partly inside said inner surface, being bowl shaped.
4 . The method according to claim 1 , wherein the step of implanting said medical device comprises implanting a device having a locking member for locking an artificial replacement of an acetabulum in a hip joint to clasp a caput femur or an artificial replacement therefore, when implanted in a hip joint of a patient, wherein said locking member is adapted to in situ assist in the fixation of the medical device, said artificial acetabulum comprising an inner surface comprising an equator line, being the largest circular circumference of said inner surface, wherein at least one extending portion of said inner surface passes beyond said equator line, such that the end portion of a contacting portion of said inner surface, the most distal portion of said inner surface adapted to contact a caput femur or artificial caput femur forms a circular extension line parallel to said equator line having a smaller circumference than said equator line, when the inner surface is placed symmetrically onto the prosthetic caput femur, wherein the method further comprises the following steps:
a) placing said locking member such that said caput femur, or artificial replacement therefore is restrained in said bowl shaped inner surface, and
b) locking said caput femur or artificial caput femur in said clasped and restrained position in said inner surface, by
c) fixating radially at least the end portion of the at least one extension portion within said circular extension line.
5 . The method according to claim 1 , further comprising the step of:
releasing said caput femur or artificial replacement therefor when a predetermined strain is placed onto said clasped caput femur or artificial replacement therefor.
6 . The method according to claim 1 , wherein the step of implanting said medical device comprises implanting a medical device having at least one extending portion comprising an elastic portion.
7 . The method according to claim 6 , wherein the step of implanting said medical device comprises implanting said medical device wherein said elastic portion comprises a spring.
8 . The method according to claim 6 , wherein the step of implanting said medical device comprises implanting said medical device wherein said elastic portion is further supported by an elastic band.
9 . The method according to claim 8 , wherein the step of implanting said medical device comprises implanting said medical device wherein said elastic band is adapted to at least partly encircle the caput femur.
10 . The method according to claim 1 , wherein the step of implanting the medical device comprises implanting a medical device being adapted to slide said at least one extending portion against the caput femur or artificial replacement therefor to release said caput femur or artificial replacement therefore.
11 . The method according to claim 1 , wherein the step of implanting the medical device comprises implanting a medical device adapted to roll said at least one extending portion against the caput femur or artificial replacement therefor to release said caput femur or artificial replacement therefor.
12 . The method according to claim 11 , wherein the step of implanting the medical device comprises implanting a medical device wherein said at least one extending portion comprises a ball shaped part adapted to roll against the caput femur.
13 . The method according to claim 1 , wherein said step of placing the caput femur or the prosthetic replacement therefore having a spherical portion, entails a second extending portion clasping the caput femur, or prosthetic caput femur, and restraining said caput femur, or said prosthetic caput femur in said medical device.
14 . The method according to claim 13 , wherein the step of implanting the medical device comprises implanting a medical device wherein said extending portion and said second extending portion together define an intermediate void adapted to receive an outer portion of a collum femur or a prosthetic collum femur when the collum femur or prosthetic collum femur is moved from its neutral position towards said void.
15 . The medical device according to claim 1 , wherein the step of implanting the medical device comprises implanting a medical device wherein said extending portion comprises a movable portion or portion.
16 . The medical device according to claim 1 , wherein the step of implanting the medical device comprises implanting a medical device comprising at least one slit forming said at least one extending potion.
17 . The medical device according to claim 16 , wherein the step of implanting the medical device comprises implanting a medical device comprising a plurality of slits, thereby forming one of said at least one extending portion between a pair of slits.