Distal Femoral Bone Harvest For Sub-Articular Grafting: A new technique and case report
by
Chadwick Prodromos MD and Brett Keller BS BA
PURPOSE: It is sometimes necessary to fill sub-articular bony defects with autologous bone as part of a program of joint restoration. Typically the autologous bone is harvested from the iliac crest. We hypothesized that harvesting a graft from the distal femoral metaphysis using coring reamers would substantially reduce surgical time and post-operative pain, and improve graft defect filling.
METHODS: The surgical technique as used in a recent patient with a moderate osteochondritis dissecans bone defect and much larger cartilage defect is as follows. The knee was exposed through a midline arthrotomy. A 2 cm coring reamer (Arthrex, Inc., Naples, FL, USA) was used to produce a cylindrical defect centered over the medial femoral condyle (MFC) defect and brought to a depth equal to the deepest part of the defect. This same coring reamer was then used to remove a depth-matched plug of cortico-cancellous bone from the distal medial femoral metaphysis, leaving the far cortex intact. Prior to removal, the twelve o’clock position was marked on both the plug and the adjacent femoral metaphysis. The cortical cap was then separated from the cancellous bone with an osteotome. A small hole was drilled into the cortical cap at the twelve o’clock mark 5 millimeters from the edge of the cap and into the distal femur near the 12 o’clock mark present there. Allomatrix Custom bone paste (Wright Medical Technology, Inc., Arlington, TN, USA) was then used to fill the defect in the distal femur. The cap was press fit into place and a #5 braided suture was used to secure the cap. The cancellous bone was then inserted into the matching intra-articular recipient site and impacted with a bone tamp. An articular cartilage implantation (ACI) “sandwich” graft using two periosteal grafts was then performed. The patient then underwent an external-fixation valgization bone transport high tibial osteotomy.
RESULTS: Post-operative knee pain was not greater than that typically encountered from the ACI procedure alone. The patient’s distal femoral donor site and MFC recipient site healed well radiographically by three months post-operatively. The patient was completely pain free and walking without a limp by the fourth month after surgery.
CONCLUSION: Bone graft harvest for intra-articular grafting can safely and effectively be accomplished from the distal femur using coring reamers. Surgical time and pain are much less than for iliac grafting. Press fitting of the size-matched plug is simpler and provides better fill than iliac piece grafting.