Osteochondral Allograft: More Efficient Donor-Host Matching?

In order to effectuate a fresh osteochondral allograft transplantation, donor and host should be well matched. According to recent work from Patrick McCulloch, M.D. at Houston Methodist Orthopedics & Sports Medicine, there is room for improvement. Dr. McCulloch and his colleagues have developed a new method to improve the accuracy of this matching based upon the cartilage surface’s arc of curvature.

Dr. McCulloch told OTW, “Osteochondral allograft transplantation using bone and cartilage from a healthy donor is an effective strategy for treating cartilage defects in the knee. However, matching patients with grafts can be challenging, leading to some grafts being wasted while many patients have long wait times for a graft to become available. Furthermore, there has been a significant increase in the number of osteochondral allograft transplantation procedures being performed in the U.S., making improved graft matching an important priority. Current algorithms for matching donors using two-dimensional sagittal and coronal dimensions often prevent the timely use of these grafts, prolonging implantation wait times for patients and wasting potential graft tissue. Therefore, the purpose of this investigation was to determine if femoral condyle radius of curvature (RoC) has the potential to be an appropriate isolated matching criterion for donor-host matching in fresh osteochondral allograft in the knee.”

“First, we evaluated the feasibility of articular reconstruction using donor-host pairs matched by radius of curvature. In the second portion, the conventional osteochondral allograft donor-host matching technique was compared to matching by the sagittal and coronal radius of curvature. In each case, a high resolution FARO laser scanner with a 35 µm resolution was used to generate three-dimensional surface models of 14 fresh frozen cadaveric distal femur hemicondyles. The sagittal and coronal radii of curvature were determined using computational model development software. While alternative, clinically-available measurement techniques were considered, including the use of computerized tomography (CT) or magnetic resonance imaging (MRI) scans to determine the radius of curvature or the use of a physical template to estimate the radius of curvature, we selected higher resolution modalities given their benefit in a proof-of-concept study.”

“At present, tissue banks only provide the linear width and length measurements on their allograft. They do not include a measure of the radius of curvature. However, adding this measurement by holding commercially available templates up to the donor condyles at the time of processing would be the first step. Surgeons could then begin measuring RoC on their patients knees using CT or MRI scans pre-operatively. They could also be used intra-operatively to find the best place on the donor condyle to find a perfect match for their defect.”

“This investigation has demonstrated that restoration of the articular surface geometry can be reliably achieved to within 1mm using the femoral condyle RoC in the coronal and sagittal planes (three dimensions) as an isolated matching criterion. This technique is as least as good as conventional matching with the potential to improve the ability to restore the articular surface contour. Additionally, the RoC method has the potential to significantly increase the number of available grafts and may be a useful alternative matching criteria, expanding upon current criteria, increasing the number of timely matches, and reducing the number and associated costs of wasted grafts.”