is formed to closely approximate the anatomical tissue being repaired the surgeon uses the instrumentation to fashion donor graft from the tissue specimen for osteochondral repair the procedure is described below with reference to the accompanying drawings referring first to fig1 following standard pre operative examination and diagnostic studies confirming the size and extent of the lesion 2 on an articular surface of femoral condyle 3 a standard para patellar arthrotomy is carried out to expose the defect cannulated sizers 4 in various diameters are selected to estimate and approximate coverage of the lesion 2 sizers 4 preferably are provided in 15 18 20 25 30 and 35 mm sizes referring to fig2 once the appropriate size for the recipient socket is determined a marker 5 is used to form a circumferential mark 6 on the condyle 3 around the cylinder of sizer 4 as shown in fig3 a guide pin 8 is drilled through the sizer 4 past the lesion 2 and into bone the sizer 4 is removed and a reference mark 10 is placed in a superior 12 00 o 39 clock position see fig3 referring to fig4 markings are placed on a synthetic hemi condyle 11 using the sizer 4 which was previously utilized to establish the recipient defect size and mark the condyle 3 the sizer 4 is placed over the synthetic hemi condyle 11 and is used to circumferentially mark 12 the surface of the hemi condyle 11 in an area corresponding to that of the lesion 2 on the damaged articular surface of condyle 3 the sizer is removed and a reference mark 13 is placed in a.