METHODS AND APPARATUS FOR LOCKING A BAND
A surgical fastening mechanism for releasably locking an implantable tether includes a housing having a central channel. The housing has an entry aperture, an exit aperture and a side channel extending therebetween. A roller element has a sidewall with an aperture therethrough and the roller is slidably disposed at least partially in the central channel such that the entry and exit apertures are at least partially aligned with the roller aperture. This permits passage of the tether therethrough. Rotation of the roller element in a first direction winds the tether around the roller thereby creating a friction interface between the roller element, the housing and the tether. A locking mechanism is operably connected with either the housing or the roller element and is adapted to prevent rotation of the roller in the central channel and also adapted to prevent release of the tether from the roller.
1 . A method for releasably locking an implantable surgical tether, said method comprising:
advancing the tether through an aperture in a housing;
advancing the tether through an aperture in a roller element, the roller element at least partially disposed in the housing;
rotating the roller element in a first direction so as to retract the tether into the housing thereby creating friction between the roller element and the housing; and
releasably locking the roller element in position relative to the housing.
2 . The method of claim 1 , further comprising threadably engaging the roller with the housing.
3 . The method of claim 1 , wherein rotating the roller in a first direction comprises rotating the roller approximately 180 degrees.
4 . The method of claim 1 , wherein rotating the roller comprises rotating the roller a selected amount so as to retract a desired length of the tether into the housing.
5 . The method of claim 4 , wherein the selected amount ranges from about a ¼ turn to about two full revolutions of the roller element.
6 . The method of claim 1 , wherein rotating the roller element in a first direction locks the tether in position relative to the housing.
7 . The method of claim 1 , wherein rotating the roller element comprises rotating a tool engaged with the roller element.
8 . The method of claim 1 , wherein rotating the roller element retracts both a working end and a tail end of the tether inward toward the roller.
9 . The method of claim 1 , wherein rotating the roller element simultaneously locks the roller element in position.
10 . The method of claim 1 , wherein releasably locking the roller element comprises placing a pin in the housing.
11 . The method of claim 1 , wherein releasably locking the roller element comprises threadably engaging a set screw with the housing.
12 . The method of claim 1 , wherein releasably locking the roller element comprises threadably engaging the roller element with the housing.
13 . The method of claim 1 , wherein releasably locking the roller element comprises pressing the roller element into the housing thereby creating a friction fit therebetween.
14 . The method of claim 1 , wherein releasably locking the roller element comprises constraining longitudinal movement of the roller element in a central channel of the housing, thereby also limiting rotation of the roller element.
15 . The method of claim 1 , further comprising aligning the housing aperture with the roller aperture to permit advancement of the tether therethrough.
16 . The method of claim 1 , further comprising rotating the roller element in a second direction opposite the first direction thereby unwinding the tether from the roller element and reducing the friction fit between the roller element, the tether and the housing.
17 . The method of claim 1 , further comprising monitoring a position indicator, the indicator indicating the relative position of the roller with respect to the housing.
18 . The method of claim 1 , wherein the implantable tether comprises a spinous process constraint device adapted to limit flexion between adjacent spinous processes or between a spinous process and a sacrum.
19 . The method of claim 1 , wherein the implantable tether comprises a tether adapted to hold two or more anatomic structures together.
20 . The method of claim 1 , wherein the roller element and the housing are held together and are inseparable from one another while the construct of the roller element and the housing is undamaged.
21 . The method of claim 1 , further comprising maintaining the tether in an undeformed configuration along planes in which the tether lies.
22 . The method of claim 21 , further comprising deforming the tether along a plane transverse to planes in which the tether lies.
23 . The method of claim 1 , wherein advancing the tether through the aperture in the housing and advancing the tether through the aperture in the roller element are performed in a single linear motion.