Takashi Ohnishi, Presenter: Nothing to Disclose

Masahiko Suzuki MD, Abstract Co-Author: Nothing to Disclose

Tatsuya Kobayashi MD, Abstract Co-Author: Nothing to Disclose

Shinji Naomoto, Abstract Co-Author: Nothing to Disclose

Tomoyuki Sukegawa, Abstract Co-Author: Nothing to Disclose

Atsushi Nawata, Abstract Co-Author: Nothing to Disclose

Hideaki Haneishi PhD, Abstract Co-Author: Nothing to Disclose

 In diagnosis and treatment of knee joint diseases, it is effective to acquire 3D motion information about the knee joint. We have previously proposed a method for 3D motion acquisition of the human knee using bi-plane fluoroscopy and CT images. However, parameters such as the facet space map between the bones are required in the diagnosis and treatment. In this paper, we developed a procedure to generate the facet space map of the femorotibial joint surface and patellofemoral joint surface.

 3D motion information is provided by 2D/3D registration. Both bi-plane dynamic fluoroscopy and CT images are acquired. Next, bone regions are segmented from the CT image. Digitally reconstructed radiographs (DRRs) of segmented bones are generated by perspective projection and compared with real fluoroscopy images. Segmented bone data are translated and rotated until the DRRs match the real images. The resultant information provides the 3D knee joint movement as the 3D motion information.  The facet space maps are generated by computing the minimum distance between each point on the tibial or patellal surface and all points on the femoral surface. Every facet space map is limited within a range of 0 to 10 [mm].

  An experiment with 10 healthy volunteers and 10 knee OA patients was conducted. The facet space maps of a typical healthy volunteer and a typical patient were visualized (Fig. 1-a). The minimum distances for the patient were narrower and more widely distributed than in the healthy volunteer for any flexion angle. In particular, the minimum distance of the femorotibial medial component of the patient was very narrow.   Femorotibial facet space maps at the 45-degrees flexion angle were visualized for all subjects (Fig. 1-b). Similar tendencies to the above-mentioned result were found.

 We developed a procedure to generate the facet space map and found through an experiment that the minimum distance for a knee OA patient was narrower and more widely distributed than for a healthy volunteer. This observation should be next investigated from an orthopedic viewpoint. We believe that the analysis procedure is useful in diagnosis.

 The developed procedure can be used in diagnosis of osteoarthritis by calculating some quantitative features such as ratio of minimum distance between medial and lateral component.

Ohnishi, T, Suzuki, M, Kobayashi, T, Naomoto, S, Sukegawa, T, Nawata, A, Haneishi, H, Facet Space Map Comparison of Femorotibial and Patellofemoral Joint Surfaces between Knee OA Patients and Healthy Subjects.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043684.html