BONE SCREWS WITH ENHANCED FATIGUE RESISTANCE AND RELATED KITS AND METHODS
The present bone screws—and kits and methods utilizing such bone screws—provide enhanced fatigue resistance (EFR), increased fixation strength, and/or improved tactile feedback. The enhanced fatigue resistance can increase the working life of a bone screw and reduce the possibility of a bone screw cracking or breaking and possible adverse implications thereof. The improved tactile feedback can improve usability by maintaining a level friction and resistance (during insertion of the screws into bone) that is familiar to health care providers. The present bone screws, kits, and methods may be configured and/or implemented for use in the repair of cancellous and/or cortical bone.
1 . A bone-screw, comprising:
an elongated shank extending from a proximal end to a distal tip, where the shank defines one or more threads along at least a portion of a length of the shank;
a head coupled to the proximal end of the shank, the head having a transverse dimension that is larger than a corresponding transverse dimension of the proximal end of the shank; and
a Type II (e.g., per AMS 2488 for titanium and its alloys) anodized surface layer on the shank.
2 . The bone screw of claim 1 , where the anodized surface layer extends over the head and/or is roughened over at least part of the thread(s).
3 . The bone screw of claim 1 , where the head is unitary with the shank and defines a recess configured to receive a driver, or the head is unitary with a single use driver that is configured to be broken or otherwise separated from the head after the screw is inserted into bone.
4 . The bone screw of claim 1 , where the threads are configured as self-tapping and/or self-drilling helical thread(s).
5 . The bone screw of claim 4 , where the shank defines a longitudinal, self-tapping notch extending through a portion of the helical thread(s) from the distal tip toward the proximal head.
6 . The bone screw of claim 1 , where the shank defines a longitudinal channel extending through the distal tip toward the proximal head or a longitudinal channel extending through the proximal head.
7 . The bone screw of claim 1 , where part of the shank is not threaded.
8 . The bone screw of claim 1 , where a portion of the anodized surface layer has been roughened by aluminum oxide blasting.
9 . The bone screw of claim 1 , where the distal tip is rounded.
10 . The bone screw of claim 1 , where the shank and head each comprise at least one material selected from the group of materials consisting of: a biocompatible metal, stainless steel, 316L stainless steel, and titanium.
11 . A kit comprising:
a bone screw of claim 1 ; and
a package within which the bone screw is sealed.
12 . A method of manufacturing a bone screw of claim 1 , the method comprising:
forming a Type II anodized surface layer that overlies at least part of one or more thread(s) defined by an elongated shank of a bone screw, the shank extending from a proximal end to a distal tip, where the shank defines the thread(s) along at least a portion of a length of the shank, the bone screw further comprising a head coupled to the proximal end of the shank, the head having a transverse dimension that is larger than a corresponding transverse dimension of the proximal end of the shank.
13 . A method of manufacturing a bone screw of claim 2 , the method comprising:
roughening a Type II anodized surface layer that overlies at least part of one or more thread(s) defined by an elongated shank of a bone screw, the shank extending from a proximal end to a distal tip, where the shank defines the thread(s) along at least a portion of a length of the shank, the bone screw further comprising a head coupled to the proximal end of the shank, the head having a transverse dimension that is larger than a corresponding transverse dimension of the proximal end of the shank.
14 . The method of claim 13 , further comprising:
prior to roughening the Type II anodized surface layer, anodizing the shank to form the Type II anodized surface layer.
15 . The method of claim 12 , where the head is unitary with the shank and defines a recess configured to receive a driver, or the head is unitary with a single-use driver that is configured to be broken or otherwise separated from the head after the screw is inserted into bone.
16 . The method of claim 12 , where the threads are configured as self-tapping and/or self-drilling thread(s).
17 . The method of claim 16 , where the shank defines a longitudinal, self-tapping notch extending through a portion of the thread(s) from the distal tip toward the proximal head.
18 . The method of claim 12 , where the shank defines a longitudinal channel extending through the distal tip toward the head or a longitudinal channel extending through the proximal head.
19 . The method of claim 12 , where the shank and head each comprise at least one material selected from the group of materials consisting of: a biocompatible metal, stainless steel, 316L stainless steel, and titanium and its alloys.
20 . A method of modifying a bone, comprising:
providing a bone screw of claim 1 ;
rotating the bone screw into the bone to engage the threads with the bone.
21 . The method of claim 13 , where the head is unitary with the shank and defines a recess configured to receive a driver, or the head is unitary with a single-use driver that is configured to be broken or otherwise separated from the head after the screw is inserted into bone.
22 . The method of claim 13 , where the threads are configured as self-tapping and/or self-drilling thread(s).
23 . The method of claim 22 , where the shank defines a longitudinal, self-tapping notch extending through a portion of the thread(s) from the distal tip toward the proximal head.