Patent ID: 12245948

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an orthopedic implant10, and more specifically, a plate that is crescent or arcuate shaped in outline with a convex side12and a concave side14each extending between a first radiused end16and a second radiused end18and has generally coextensive (meaning that there is a relatively constant thickness22therebetween and which may include a curve or topography that is planar or curved in one or more dimensions) top24and bottom26surfaces (relative to the bone) where the thickness is sufficiently substantial to support the forces that can be applied to a human hand during use and in healing so as to support the bones during fusion. The plate includes a plurality of fixation holes30, such as first32and second34tapered threaded or otherwise locking screw holes in a first end of the arc and a second end of the arc that receives locking screws38. The FIGS. illustrate three version of the plate,10,10′ and10″ in which the reference numerals are differentiated also by the use of o′, and o″ for the variations in the compression hole well44,44′ and44″.

The implant of the present invention is a crescent or kidney shape (i.e. a plate having an arcuate foot-print and a uniform through thickness through-out at least half of the surface area of its body and co-planar top and bottom surfaces perforated by one or more through openings which are preferably threaded so as to accept locking screws) of appropriate length (i.e. 2-3 cm), width (i.e. 5-20 mm) and thickness (i.e. 1-3 mm). In addition, the plate includes a recessed screw opening40that receives and supports one or more screws42(typically self-tapping, locking or non-locking threaded cancellous screws of from 10 to 40 mm in length), such as a lag screw, at an oblique angle relative to the plane of the top surface. This screw can be used for the compression or reduction of a bone or bone fragment, often preferably the lunate in wrist fusion procedures.

In various embodiments, the reduction recess44(or recesses) is located at the convex side of the crescent profile. In the first embodiment, which includes a single reduction recess, the recess including a well comprising a side wall46that extends downward from the top surface of the plate (i.e. from 2 to 6 mm) and a bottom wall48which surrounds the through hole40for the lag screw. The bottom wall48supports the back side50of the reduction or lag screw head in use and helps to define the angle provided by the screw relative to the top surface of the plate which supports or is supported by the other carpal bones (i.e. the capitate, the hamate, and the triquetrum) while the reduction screw fastens the lunate relative to the remainder of the construct. The edge of the recess which contains the hole40forms a rim that resides in a recess countersunk into the bone to help to confine the bone into which it is set. In this embodiment, the first and second ends of the arc-shaped plate are held in position on the capitate on one side and the triquetrum on the other. In various embodiments shown, the entry position of the lag screw is defined according to the placement of the reduction recess on the arc at the convex side of the plate so that the proximal end of the screw can be nearer the end of the plates at the capitate, or the triquetrum or in the center at the hamate.

In a variation of this embodiment shown inFIGS.9-14, the plate110has two reduction recesses144with openings140and bottom screw walls148that define the retaining areas248surrounding the bottom of the screw heads for two screws250. Here, the side walls of the reduction recesses form conjoined circular rims that form a teeth shape to provide better leverage in the underlying bone. Also, this version is shown with threaded locking screw holes for the lag screws150. The distal ends of these screws converge so as to provide increased resistance to pull-out. The plate is also illustrated including a pair of laser etched lines150that are aligned with the reduction recesses and can be used to help orient the plate.

The plate has a length which is between 0.5 and 1.5 inches, a width of from 0.2 and 0.75+/−0.01 inches, a thickness of 0.04 to 0.3+/−0.05 inches and the compression screw wells have a depth of from 0.1 to 0.25+/−0.05 inches.

In an alternative version of this plate210, the reduction recesses244can be located on each side of the arc with recesses244defined in opposing planes, here for example 150°+/−20° apart, so as to capture the hamate as well as the lunate.

In a second embodiment of the outline of the plate, the plate310has a tri-corner extension so that a third arm 3i 5 is available for one or more of the reduction recesses344. More particularly, the extension has a lag screw350that extends away from the center of the plate in a direction below the top (i.e., away from the bone) surface of the plate at an angle of from 75° to 60°+/−10° relative to a plane defined at the top surface of the plate, and the reduction recess also includes a second opening defined at a different angle relative to the plate i.e. from 15° to 45°+/−10°, such that the angle between the two lags screws in position is from 75° to 120°. Preferably, these screws are fixed angle locking screws, as are the end screws.

FIG.33illustrates four methods of wrist fusion that use the system of the present invention. InFIG.33(a), the template is secured using olive wires, while the template is secured with k-wires inFIG.33(b), and inFIG.33(c)a starter tip reamer is used, while a cannulated reamer is used inFIG.33(d).

In the first procedure as illustrated the carpals are prepared for the fusion with a dorsal exposure of the carpal area. The scaphoid bone is excised and a special clamp having offset arms is used to reduce the lunate by grasping the outer carpals, the triquetrium and the capitate and rotating the offset jaws of the clamp about a medial axis of the clamp so as to move the capitate palmarly which in turn causes the lunate to rotate dorsally. Once the carpals are re-positioned, the fixation procedure can begin in one of four illustrated manners. In the first one, a template400is positioned spanning the triquetral, and capitate with the laser guide lines directed at the lunate. Then, the template is fixed to the triquetral with an olive wire and the capitate is reduced and fixed using an olive wire. A reamer404is used to countersink through the template for the compression screw wells. The olive wires and template are removed, and the plate is positioned ensuring that the laser marks are directed at the lunate. The plate is fixed using a screw to the triquetral and then to the capitate, and then the lunate is fixed (and reduced) using compression screws through the compression screw holes such that the final reduction of the lunate can be accomplished using the plate screw system. In a second procedure, k-wires405are used rather than the olive wires, and the procedure is similar, except the k-wires can be used to hold the position of the reduced bones, and the template400is slide off the k-wires and the plate is slide onto the k-wires. In a third procedure, a template400′ is placed on the carpals with laser marks directed at the lunate and a reamer404′ having a trocar tip is used to create starter holes at the compression screw wells which are then reamed to full depth. These countersunk holes are used to position the plate which is secured as previously described. In a fourth version of the procedure, the template400′ is placed using the laser marks, and k-wires are driven through k-wire holes in the template and a cannulated reamer404″ is used over the k-wires405to drill holes for the end screws and at the compression screw holes. The template is removed and the plate is placed and secured.

The present involves a unique clamp500that has a locking scissoring pair of jaws502joined at a pivot point501and having pincer ends which are offset from a plane defined by the handles of the clamp. The clamp also includes typical handles504having finger holes and a locking spacer508with a threaded cross member509and locking nut510or a ratchet and pawl type locking means. One pincer end includes a single tine512which has a pivot tip normal to the length of its arm which fixes the triquetral, and the other pincer end has an L-bracket514with a tine516that supports the capitate dorsally. After the surgeon grabs these carpals with the clamp, he or she can twist the clamp to cause the capitate to move palmarly which in turn forces the lunate to rotate and move upward so as to help reduction into a preferred position for fusion.

FIGS.37,38, and39illustrate a reamer guide540with a plate template542and handle555and with a reamer544engaged in one of the compression/reduction screw holes of the guide.FIG.37shows the reamer-template assembly from the front view overlaid with the plate548to illustrate how the reamer and template are shaped to match the plate shape.FIG.38shows the assembly ofFIG.37from the back view, andFIG.39shows the assembly on a wrist from the side with k-wires546. Following the reaming step, the reaming guide is removed by sliding it off the k-wires and a plate548is positioned over the k-wires546as is shown inFIG.41.FIG.42shows a plate548in position with the reduction holes positioned into the counterbores which have been reamed out, and a drill guide550in position for the reduction screws.

FIGS.43and44illustrate a side and top view of the plate548with screw assembly after the screws552have been implanted through the plate, and for clarity,FIG.45shows the plate548in a plate assembly558(minus one reduction screw556but with both of the end screws559). This view illustrates a variable locking mechanism560which includes interruptions561in the threads563of the screw holes564which allow a threaded screw head565to bear against the threads562and wedge into a variable locking relationship.FIG.46shows a cross-section of the plate taken through a reduction hole in order to illustrate the configuration of the screw holes564.FIG.47is a view from the bottom side of the plate.