Garry Evan Gold MD, Presenter: Nothing to Disclose

Thor F Besier PhD, Abstract Co-Author: Nothing to Disclose

Christine F Draper MS, Abstract Co-Author: Nothing to Disclose

Deanna S Asakawa PhD, Abstract Co-Author: Nothing to Disclose

Scott L Delp PhD, Abstract Co-Author: Nothing to Disclose

Gary S Beaupre PhD, Abstract Co-Author: Nothing to Disclose

To measure patellofemoral cartilage contact areas while upright and weight bearing using an open MRI and a custom back support.

We examined 16 healthy volunteers (8 males, 8 females) at 0, 30, and 60 degrees of knee flexion in weight bearing and non-weight-bearing conditions. MR scanning was performed in a 0.5T GE Signa SP open MRI scanner using a custom back support device that allows subjects to remain motion-free for the duration of the scan. Scanning was done using a transmit-receive surface coil with a sagittal 3D spoiled gradient echo sequence (3D-SPGR) and a 20 cm field-of-view. Imaging matrix was 256x160 with a TR/TE of 33/9ms and a 45-degree flip angle. We acquired 32 sections of 2 mm thickness in a scan time of 2:13m. In vivo contact areas were measured between the patella and femoral cartilage at each flexion angle. Total contact areas without load and with load (approximately 0.45 times body weight supported by each leg) were compared.

Patellofemoral cartilage contact area increased with flexion angle and weight bearing. At 0 degrees of flexion, average contact area increased from 205±65 mm˛ (non-weight bearing) to 313±113 mm˛ (weight bearing) in males, and 171±50 mm˛ (non-weight bearing) to 182±70 mm˛ (weight bearing) in females. At 30 degrees of flexion, average contact area increased from 427±76 mm˛ to 512±54 mm˛ in males, and 269±68 mm˛to 362±84 mm˛ in females. At 60 degrees of flexion, average contact area increased from 530±100 mm˛ to 648±102 mm˛ in males, and 396±115 mm˛ to 518 ±144 mm˛ in females. Contact area increased for all subjects with weight bearing at each flexion angle (p < .01, paired t-test).

The increase in contact area we observed under load could be due to repositioning the patella in the trochlear groove and to cartilage deformation from loading. Sixteen patellofemoral patients are being studied and will be compared with the healthy volunteers to determine if contact areas are different in subjects with patellofemoral pain.

Gold, G, Besier, T, Draper, C, Asakawa, D, Delp, S, Beaupre, G, Upright Weight Bearing MRI of Patellofemoral Joint Cartilage Contact Area.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4412529.html