US 12,220,154 B2
Motor-driven fixator to apply micromotion to fracture site to accelerate bone healing
Weichen Qi, Hong Kong (HK); Xiaoreng Feng, Hong Kong (HK); and Ka-Li Leung, Hong Kong (HK)
Assigned to THE UNIVERSITY OF HONG KONG, Hong Kong (HK)
Appl. No. 17/784,731
Filed by THE UNIVERSITY OF HONG KONG, Hong Kong (HK)
PCT Filed Dec. 11, 2020, PCT No. PCT/CN2020/135629
§ 371(c)(1), (2) Date Jun. 13, 2022,
PCT Pub. No. WO2021/115418, PCT Pub. Date Jun. 17, 2021.
Claims priority of provisional application 62/947,569, filed on Dec. 13, 2019.
Prior Publication US 2023/0000524 A1, Jan. 5, 2023
Int. Cl. A61B 17/72 (2006.01); A61B 17/64 (2006.01); A61B 17/66 (2006.01); A61B 17/00 (2006.01); A61B 17/56 (2006.01)
CPC A61B 17/66 (2013.01) [A61B 17/6475 (2013.01); A61B 2017/00017 (2013.01); A61B 2017/564 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An external fixator for treating bone fractures, the external fixator comprising:
a holder attached to bone at two fracture fragments, the two fracture fragments respectively on opposite sides of a fracture site;
a micromotional unit removably coupled to the holder, the micromotional unit configured to produce a reciprocating displacement between the two fracture fragments to apply a controllable micromotion to the fracture site; and
a controller coupled to the micromotional unit, the controller configured for controlling the micromotional unit to produce the reciprocating displacement between the two fracture fragments,
wherein the micromotional unit comprises an outer tube, an inner tube, a motor, and a gear drive, and at least a portion of the inner tube is inserted inside the outer tube,
wherein the motor and the gear drive are configured to transform an electrical signal from the controller into a relative axial displacement between the outer tube and the inner tube along an axial direction of the inner tube and the outer tube,
wherein the outer tube and the inner tube are respectively connected with the two fracture fragments, so that the relative axial displacement between the outer tube and the inner tube produces the reciprocating displacement between the two fracture fragments,
wherein the gear drive is a harmonic gear drive, and the harmonic gear drive comprises a strain wave generator, an elliptical gear, and a circular ring gear; and
wherein the strain wave generator is connected with an output shaft of the motor, the circular ring gear is provided on the inner tube, and the motor drives the strain wave generator to press the elliptical gear from an inside of the elliptical gear to force the elliptical gear mesh with the circular ring gear.