Patent ID: 11944358
Assignee: NUVASIVE SPECIALIZED ORTHOPEDICS, INC
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 16:
17. A lengthening device configured for placement between a first bone section and a second bone section, the device comprising:
a distraction shaft having an internal cavity disposed therein, and an axial groove disposed on an outer surface thereof, wherein the distraction shaft is configured for fixation to the first bone section;
a housing configured for fixation to the second bone section, wherein the distraction shaft is configured to be telescopically displaceable relative to, and disposed partially within the housing;
a lip seal flange attached to the housing;
a lip seal configured to allow a sliding seal between the distraction shaft and the housing, the lip seal including:
a base portion configured to seal against an inner diameter of the lip seal flange;
one or more protrusions disposed about an inner diameter of the lip seal and configured to slidingly seal against the distraction shaft; and
an inner surface configured to slidingly seal against an outer diameter of the distraction shaft,

a ball disposed within the axial groove disposed on the distraction shaft;
a ball cage disposed over the distraction shaft and the ball, the ball cage being configured to trap the ball within the axial groove;
a splined housing disposed over the ball cage and the ball, the splined housing having an axial groove disposed along an inner diameter surface of the splined housing, wherein the ball cage and the ball are interposed between the distraction shaft and the splined housing,
wherein the ball is constrained by the ball cage, and is configured to be disposed at least partially within the axial groove disposed on the distraction shaft, and at least partially within the axial groove disposed on the splined housing, thereby rotationally locking the splined housing to the distraction shaft, while allowing axial displacement of the distraction shaft relative to the splined housing; and
an actuator configured to increase at least one of a distraction force between the distraction shaft and the housing and a length of the lengthening device, the actuator including:
a permanent magnet being configured for rotation relative to the housing; and
a lead screw operatively coupled to the permanent magnet via a gear assembly.