Apparatus for knee prosthesis

Claim 1

A modular apparatus for use in the preparation of bone surfaces and the implantation of a modular total knee prosthesis in a patient, which apparatus comprises: (a) an extendable rod 10, having a distal end 2 and a proximal end, means for adjusting the length of the rod, means for adjusting the lateral alignment and angular orientation of the proximal end of the rod, clamp means 11, 12, 13 associated with the distal end of said rod for clamping said distal end to the ankle region of the patient's leg and combination fixing means 4, 5 and cutting platform 6 associated with said proximal end of the rod for attaching said proximal end to the upper end of the patients tibia while aligning the cutting platform close to the tibial plateau; (b) an adjustable stylus 20 for aligning said cutting platform at the correct level for resecting the tibial plateau; (c) a modular stem/fin template 25 for determining the peripheral size of the resected proximal tibia and including a raised cylindrical hollow tube 28 for aligning a stem/fin punch; (d) a stem/fin punch 32 comprising a central hollow cylindrical tube 33 with a distal chisel edge 34 and two fins 35 extending radially from said tube at a predetermined angle and each having a distal chisel edge; (e) a push rod 40 which fits into said hollow cylindrical tube of said stem/fin punch; (f) an alignment fork 41 attached to an intramedullary rod 42 adapted to be introduced into a medullary canal of the patient; (g) a femoral distractor comprising a handle 44, a rail 47 adapted to slide onto the alignment fork, a lateral arm 48 and a medial arm 49, each of which has associated means for separately raising and lowering each arm; (h) a drill guide 52 adapted to slide along the rail of the femoral distractor and having a plurality of holes 54 for accepting locating pins; (i) a distal cutting guide comprising a flat plate 55 having a top surface 56 and a bottom surface and integral flanges extending from said bottom surface 57 and each being inset from one edge of said surface, each of said flanges having a locating hole 60 extending therethrough; (j) a modular cutting guide for guiding a saw blade to make cuts required for a femoral component prosthesis, comprising a substantially rectangular frame 61 having a top wall 62 and a bottom wall 63, each of said walls being defined by substantially parallel planar outer and inner surfaces, wherein each outer surface provides a flat cutting plane and the inner surfaces define an open window within which is located an intermediate solid block 64 having an angled top surface 65 and an angled bottom surface 66, each of said angled surfaces providing a guide for making a chamfer cut, said angled top surface being spaced apart from the top inner surface of said window and said angled bottom surface being spaced apart from the inner bottom surface of said window by gaps which provide a surgeon with a clear view of the surface being cut; (k) a femoral sizer for determining the size of the patient's femur, comprising a body portion 68 having locating holes, a central tubular orifice 69 for accepting a feeler element and indicating means for indicating the depth of the feeler element within said orifice when the sizer 71 is located on the patient's femur, thereby providing a determination of the size required for a modular cutting guide; (l) a reamer guide for correct location of a reamer for preparing a cavity to locate a femoral prosthesis peg, which reamer guide comprises a flat plate 72 having a top surface 73 and a bottom surface 74, a hole 75 extending through the plate, a tubular bushing 76 extending from said top surface and lined up with said hole and locating pegs 77 extending from said bottom surface; (m) a patella resection guide comprising a scissor-type clamp 79 having distal gripping arms 80, each of said arms defining a cutting surface and gripping teeth 81, said gripping teeth being inset 82 below the plane 83 of the associated cutting surface; (n) a patella handling instrument providing alternative template and clamping functions comprising a scissor-type member 84 having a first pivotal arm 85 with a distal end and a second pivotal arm 86 with a distal end; the first arm having a swivable platform 87 located at its distal end, the surface 88 of said platform facing inwardly toward said second arm and said second arm having means 89 to interchangeably grip and hold either;- (i) a modular patella template 90 having holes to accept drills, or (ii) a clamp member 91 adapted to clamp a patella prosthesis to a resected patella.