Anna L. Falkowski, Presenter: Nothing to Disclose

Carlo Camathias, Abstract Co-Author: Nothing to Disclose

Jon A. Jacobson MD, Abstract Co-Author: Consultant, BioClinica, Inc Royalties, Reed Elsevier Equipment support, Terumo Corporation Equipment support, Arthrex, Inc

Olaf Magerkurth MD, Abstract Co-Author: Nothing to Disclose

To characterize MR findings of osteochondral lesions in the knee joint with regard to location, size, shape, orientation of the axes and compare these findings with a split line map of the distal femoral cartilage.

IRB approval was obtained. Patients with acute OCDs were included. The following measurements and observations were obtained: location, depth, shape and size of the OCD. Lesions with a ratio of short axis / long axis <0.6 were considered as oval and over 0.6 as round lesions. Orientation of the long and short axes were compared to a split line map. Interreader Agreement was tested with a paired two tailed t-test.  

56 patients were included in the study. 17 OCDs were located in the medial central portion of the medial femoral condyle joint surface (R13, Fig.1). The location of the other lesions were: 4 in R1, 1 in R4 and R7, 4 in R10, 6 in R11, 1 in R12, 5 in R14, 8 in R17, 4 in R19, and 1 in R20. Orientation of the long axis correlated with the split line map. In regions R10-R12, lesions were round, whereas they were oval in R4, R7 and R13-R20. Testing for interreader agreement showed no significant difference and a good correlation (p=0.067, r=0.7100).

In this study shape of osteochondral lesions in the knee joint do follow split line maps representing the layered structure of the cartilage. We assume that paying attention to orientation of autologous chondral grafts might increase stability a the recipient site and improve outcome.

The majority of osteochondral defects (OCD) in the knee joint occur in the femoral cartilage. According to the International Cartilage Repair society (ICRS) OCDs should be characterized by location (Fig. 1B), size, depth and involvement of the underlying bone. According to histological and biomechanical studies the cartilage is not an amorphous mass covering the epiphysis, but consists of a layered matrix orientated to tensile forces during motion of the joint. This layering is supposed to increase stability of the cartilage. We observed that osteochondral lesions are oval in shape and that the long axis may correlate with split lines maps (Fig. 1A) of the femoral cartilage.This might imply that in autologous chondral grafting paying attention to orientation of chondral plugs at the donor and recipient site might improve the outcome.

Falkowski, A, Camathias, C, Jacobson, J, Magerkurth, O, Osteochondral Lesions of the Femoral Cartilage follow a Distinctive Pattern: Comparison of MR findings with Split Line Maps of the Knee Joint.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015984.html