One of the most common knee surgeries currently being performed is the anterior cruciate ligament transplant. In this operation the anterior cruciate ligament is replaced by a graft from the patient's patellar tendon. The graft includes bone plugs at both ends of the tendon which are typically removed from the patient's own patella and tibia using a hammer and chisel and perhaps also a standard reciprocating saw. The bone plugs of the resultant graft must then be trimmed to an approximate circular cross section of typically either 9 millimeters or 10 millimeters in diameter for insertion into drilled out femoral and tibial tunnels.
Since the chiseled bone plugs are approximately triangular or rectangular in cross section and the desired plugs are to be circular, obviously more bone must be removed from the patient than if the means were available to cut a circular cross section plug from the donor site to begin with. Also the bone trimming process can be tedious and inexact and also quite costly since the patient must remain under anesthesia and the remainder of the operating team must stand by as one person trims the bone plugs. More time is lost if the bone plugs must be re trimmed after the initial attempt at insertion into the transplant site. Clearly a substantial improvement to this operation could be realized if a tool were available to initially cut properly sized circular cross section plugs from the donor sites.
Attempts have been made to use a conventional hole saw for cutting the plugs, but the results have not been satisfactory. A conventional hole saw cannot easily cut out a plug which must be parallel to and congruent with the surface of the bone because of the presence of the hole saw shaft. The proper entry angle could only be achieved if the bone portion opposite to the direction of the cut were first removed. This is an unsatisfactory solution since the patient is also the donor and it becomes therefore quite important to conserve intact as much of the donor's bone as possible. What is needed is a shaftless hole saw, which is the object of this invention.