Hip joint device and method
View Patent ↗A medical device for implantation in a hip joint of a patient is provided. The medical device comprises a prosthetic caput femur having least partially spherical portion and a releasing member. The releasing member is adapted to, in a first state, restrain the at least partially spherical portion in an acetabulum or a prosthetic acetabulum and, in a second state, to release the at least partially spherical portion from the acetabulum or the prosthetic acetabulum. The releasing member is further adapted to change from the first state to the second state and from the second state to the first state when a strain, exceeding a predetermined threshold, is exerted on the hip joint.
1. A medical device for implantation in a hip joint of a patient, the medical device comprising a prosthetic caput femur comprising:
an at least partially spherical portion adapted to be received in an acetabulum or a prosthetic acetabulum fixated to the pelvic bone of the patient; and
a releasing member having a first state and a second state, wherein the releasing member is adapted to, in the first state, restrain the at least partially spherical portion in the acetabulum or the prosthetic acetabulum; and in the second state, release the at least partially spherical portion from the acetabulum or the prosthetic acetabulum, and wherein
the releasing member is further adapted to change from the first state to the second state, thereby releasing the prosthetic caput femur from the acetabulum or prosthetic acetabulum, and from the second state to the first state, thereby reinstating the prosthetic hip joint in the acetabulum or prosthetic acetabulum, when a strain, exceeding a predetermined threshold, is exerted on the hip joint, and
the at least partially spherical portion is formed and sized to be compressed as the releasing member changes from the first state to the second state and/or from the second state to the first state.
2. The medical device according to claim 1 , wherein the releasing member comprises an elastic portion allowing at least part of the releasing member to assume a compressed state in response to said strain.
3. The medical device according to claim 2 , wherein the elastic portion is at least partly formed of an elastic material.
4. The medical device according to claim 1 , wherein the releasing member comprises a movable element.
5. The medical device according to claim 1 , wherein the releasing member comprises a bendable portion and/or flexible portion and/or compressible portion and/or movable portion.
6. The medical device according to claim 1 , wherein the releasing member comprises a first and a second element.
7. The medical device according to claim 6 , wherein at least one of the first and the second element is being movable in relation to the other element so as to allow the artificial caput femur to be released from the acetabulum or prosthetic acetabulum.
8. The medical device according to claim 7 , wherein at least one of the first and second element are spring loaded to assist the movement of at least one of the first and second element.
9. The medical device according to claim 7 , wherein at least one of the first and second elements are flexible.
10. The medical device according to claim 6 , wherein the first and second element at least partly forms the spherical portion.
11. The medical device according to claim 1 , wherein the releasing member further comprises a spring.
12. The medical device according to claim 11 , wherein said spring is adapted to assist the change between the first state and the second state.
13. The medical device according to claim 1 , further comprising a prosthetic acetabulum adapted to be fixated to the pelvic bone of the patient and to receive the spherical portion of the artificial caput femur when the medical device is implanted in the patient.
14. The medical device according to claim 13 , wherein the prosthetic acetabulum comprises:
an inner surface comprising an equator line, being the largest circular circumference of the inner surface; and
at least one extending portion extending beyond the equator line and being adapted to clasp the spherical portion of the artificial caput femur for restraining the artificial caput femur in the prosthetic acetabulum.
15. The medical device according to claim 14 , wherein the at least one extending portion extends longitudinally along the equator line, and at least one of:
a) dorsal to a lateral-medial axis of pelvis;
b) dorsal to the lateral-medial axis and proximal to the lateral-medial axis of pelvis;
c) dorsal to the lateral-medial axis and distal to the lateral-medial axis of pelvis; and
d) dorsal to the lateral-medial axis and distal to the lateral-medial axis of the pelvis, and the at least one extending portion extends dorsal to the lateral-medial axis and proximal to the lateral-medial axis of the pelvis.
16. The medical device according to claim 14 , wherein the at least one extending portion longitudinally extends at least one of:
a) along at least ½ of the equator line;
b) along at least ⅓ of the equator line;
c) along at least ¼ of the equator line;
d) along at least 1/10 of the equator line; and
e) along at least 1/10 the equator line, and the at second extended portion longitudinally extends along at least ¼ of the equator line.
17. A medical device for implantation in a hip joint of a patient, the medical device comprising a prosthetic caput femur comprising:
an at least partially spherical portion adapted to be received in an acetabulum or a prosthetic acetabulum fixated to the pelvic bone of the patient; and
a releasing member having a first state and a second state, wherein the releasing member is adapted to, in the first state, restrain the at least partially spherical portion in the acetabulum or the prosthetic acetabulum; and in the second state, release the at least partially spherical portion from the acetabulum or the prosthetic acetabulum, and wherein
the releasing member is further adapted to change from the first state to the second state, thereby releasing the prosthetic caput femur from the acetabulum or prosthetic acetabulum, and from the second state to the first state, thereby reinstating the prosthetic hip joint in the acetabulum or prosthetic acetabulum, when a strain, exceeding a predetermined threshold, is exerted on the hip joint, and wherein the releasing member further comprises a spring.
18. A medical device for implantation in a hip joint of a patient, the medical device comprising a prosthetic caput femur comprising:
an at least partially spherical portion adapted to be received in an acetabulum or a prosthetic acetabulum fixated to the pelvic bone of the patient; and
a releasing member having a first state and a second state, wherein the releasing member is adapted to, in the first state, restrain the at least partially spherical portion in the acetabulum or the prosthetic acetabulum; and in the second state, release the at least partially spherical portion from the acetabulum or the prosthetic acetabulum, and wherein
the releasing member is further adapted to change from the first state to the second state, thereby releasing the prosthetic caput femur from the acetabulum or prosthetic acetabulum, and from the second state to the first state, thereby reinstating the prosthetic hip joint in the acetabulum or prosthetic acetabulum, when a strain, exceeding a predetermined threshold, is exerted on the hip joint, wherein the medical device further comprises:
a prosthetic acetabulum adapted to be fixated to the pelvic bone of the patient and to receive the spherical portion of the artificial caput femur when the medical device is implanted in the patient, wherein the prosthetic acetabulum comprises:
an inner surface comprising an equator line, being the largest circular circumference of the inner surface; and
at least one extending portion extending beyond the equator line and being adapted to clasp the spherical portion of the artificial caput femur for restraining the artificial caput femur in the prosthetic acetabulum.
19. The medical device according to claim 18 , wherein the extending portion is arranged to be placed dorsal to the proximal-distal axis Y, when implanted, and wherein the artificial acetabulum further comprises a second portion not extending beyond the equator line and extending along at least ½ of the equator line and frontal to the proximal-distal axis Y, such that the motion range of the hip joint is limited in a non-restrictive way.
20. The medical device according to claim 18 , wherein the at least one extending portion adapted to clasp the spherical portion of the artificial caput femur comprises an elastic portion.
21. The medical device according to claim 20 , wherein the elastic portion comprises an elastic material.