SYSTEM AND METHODS FOR PATELLAR TENDON ADVANCEMENT IN QUADRUPEDS
Various methods and apparatus for cranially advancing the tuberosity and patellar tendon of a quadruped are disclosed. The patellar tendon can be advanced directly or indirectly by performing an osteotomy on the tuberosity, and subsequently advancing the tuberosity cranially to an advanced position. Implants are further disclosed for maintaining the patellar tendon, and in some embodiments also the tuberosity, in the advanced position.
1 . A TTA implant configured to maintain an advanced tuberosity or a quadruped in an advanced position relative to a tibial body, the advanced position being spaced cranially with respect to a first position when the tuberosity is integral with the tibial body, the TTA implant comprising:
a distal end that defines a plurality of bone anchor holes each configured to receive a bone anchor so as to attach the distal end to the tibial body;
a proximal end configured to support the advanced tuberosity in the advanced position; and
an intermediate portion that extends between the proximal and distal ends, the intermediate portion shaped so as to space the proximal end cranially with respect to the distal end an amount sufficient so as to maintain the advanced tuberosity in the advanced position,
wherein the TTA implant defines a spacer that is integral and monolithic with the proximal end, the spacer extending cranially from the proximal end so as to fit within a gap disposed between the advanced tuberosity and the tibial body when the distal and proximal ends are attached to the tibial body and the advanced tuberosity, respectively.
2 . The TTA implant as recited in claim 1 , further comprising an implant body that defines the distal end, the proximal end, and the intermediate portion, wherein the spacer extends from the implant body at the proximal end along a medial-lateral direction at a location so as to abut a caudal surface of the advanced tuberosity.
3 . The TTA implant as recited in claim 3 , wherein the implant body defines first and second legs that are spaced from each other, such that the spacer is attached to both legs.
4 . The TTA implant as recited in claim 1 , wherein the proximal end defines a plurality of bone anchor holes each configured to receive a bone anchor so as to attach the proximal end to the advanced tuberosity.
5 . The TTA implant as recited in claim 4 , further comprising an implant body that defines the distal end, the proximal end, and the intermediate portion, wherein the spacer is cut out from the implant body at the proximal end.
6 . The TTA implant as recited in claim 5 , wherein the spacer is flexible.
7 . The TTA implant as recited in claim 4 , wherein the distal end defines three of the bone anchor holes that are aligned with each other.
8 . The TTA implant as recited in claim 4 , wherein the distal end defines a medial side that is configured to extend along at least a portion of a medial side of the tibial body, and the distal end further defines a lateral side that is configured to extend along at least a portion of a lateral side of the tibial body.
9 . The TTA implant as recited in claim 8 , further comprising first and second opposed legs 72 a and 72 b that can be spaced along a medial-lateral direction, each of the legs defining a respective intermediate portion and a respective proximal end that is cranially spaced from the distal end.
10 . The TTA implant as recited in claim 9 , wherein the spacer extends from at least one of the first and second legs toward the other of the first and second legs.
11 . A TTA implant configured to maintain an advanced tuberosity or a quadruped in an advanced position relative to a tibial body, the advanced position being spaced cranially with respect to a first position when the tuberosity is integral with the tibial body, the TTA implant comprising:
an implant body including:
a distal end that defines a plurality of bone anchor holes each configured to receive a bone anchor so as to attach the distal end to the tibial body;
a proximal end configured to receive a bone anchor so as to attach the proximal end to the advanced tuberosity; and
an intermediate portion that extends between the proximal and distal ends, the intermediate portion shaped so as to space the proximal end cranially with respect to the distal end an amount sufficient so as to maintain the advanced tuberosity in the advanced position; and
an expandable spacer that is separate from and not directly attached to the implant body and is configured to be disposed in a gap defined between the advanced tuberosity and the tibial body, so as to resist movement of the advanced tuberosity toward the first position, the spacer comprising:
a first spacer body and a second spacer body spaced from the first spacer body and expandable with respect to the first spacer body along a cranial-caudal direction when the expandable spacer is disposed in the gap, the first spacer body defining a first bone facing surface configured to engage the advanced tuberosity, and the second spacer body defining a second bone facing surface configured to engage the tibial body.
12 . The TTA implant as recited in claim 11 , further comprising an articulation member that is operably coupled to the first and second spacer bodies, such that movement of the articulation member from a first position to a second position causes at least one of the first and second spacer bodies to move away from the other of the first and second spacer bodies.
13 . The TTA implant as recited in claim 12 , wherein the articulation member is rotatable about an axis of rotation, such that the second position is angularly offset with respect to the first position.
14 . The TTA implant as recited in claim 13 , wherein the articulation member is rotatably eccentrically about the axis of rotation.
15 . The TTA implant as recited in claim 12 , wherein the articulation member includes a first articulation member portion and a second articulation member portion that receive an actuator, such that the rotation of the actuator about an axis of rotation causes the first and second articulation member portions to bias the first and second spacer bodies away from each other.
16 . A TTA implant configured to maintain an advanced tuberosity or a quadruped in an advanced position relative to a tibial body, the advanced position being spaced cranially with respect to a first position when the tuberosity is integral with the tibial body, the TTA implant comprising:
a distal end that defines a plurality of bone anchor holes each configured to receive a bone anchor so as to attach the distal end to the tibial body, at least two of the plurality of bone anchor holes aligned along a longitudinal axis;
a proximal end configured to receive a bone anchor so as to attach the proximal end to the advanced tuberosity; and
an intermediate portion that extends between the proximal and distal ends, the intermediate portion shaped so as to space the proximal end cranially with respect to the distal end an amount sufficient so as to maintain the advanced tuberosity in the advanced position,
wherein a center of a proximal-most one of the bone anchor holes of the distal end is spaced from a distal end of the advanced tuberosity a distance along the a direction substantially parallel to the longitudinal axis, the distance within a range from and including approximately 30 mm to approximately 40 mm.
17 . The TTA implant as recited in claim 16 , wherein the intermediate portion is elongate along a central axis, and the central axis defines an angle with respect to the longitudinal axis within the range of approximately 23.7° and approximately 30.2°.
18 . The TTA implant as recited in claim 17 , wherein the implant includes an implant body that defines the proximal end, the intermediate portion, and the distal end, and the implant is devoid of a spacer that is separate from the implant body and configured to be disposed in a gap defined between the advanced tuberosity and the tibial body.
19 . A method for advancing a tuberosity of a quadruped from a first position to an advanced position that is cranially spaced from the first position, the method comprising the steps of:
creating a cut line in a tibia of the quadruped so as to separate at least a portion of the tuberosity from a tibial body;
advancing the portion of the tuberosity along the cut line to the advanced position; and
attaching an implant to both the tibial body and the advanced portion of the tuberosity so as to secure the tuberosity in the advanced position with respect to the tibial body.
20 . The method as recited in claim 19 , wherein the creating step further comprises the step of creating a proximal cut line and a distal cut line, and the advancing step further comprises advancing the portion of the tuberosity along the proximal cut line.
21 . The method as recited in claim 20 , wherein the creating step further comprises the step of positioning the distal cut line at a position such that an attachment location of a patellar tendon to the tuberosity is disposed between the proximal and distal cut lines.
22 . The method as recited in claim 20 , wherein the creating step further comprises the step of positioning the distal cut line at a position such that the distal cute line is positioned between the proximal cut line and an attachment location of a patellar tendon to the tuberosity.
23 . The method as recited in claim 19 , wherein the creating step further comprising creating a curvilinear cut line into the tibia, and the advancing step further comprises rotating the separated portion of the tuberosity along the cut line.