1. Surface Damage of Patellar Components Used in Total Knee Arthroplasty by Michael A. Conditt, Philip C. Noble, Bryce Allen, Ming Shen, Brian S. Parsley, and Kenneth B. Mathis J Bone Joint Surg Am Volume 87(6):1265-1271 June 1, 2005 ©2005 by The Journal of Bone and Joint Surgery, Inc.

2. Examples (left to right) of the dome-shaped, sombrero-shaped, and pseudo-anatomic patellar designs. Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.

3. Division of the articular surface into four peripheral zones and one central zone for evaluation of damage. Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.

4. Examples of damage mechanisms observed on the retrieved patellar components. Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.

5. The severity of damage, of the eighty-five patellar components, caused by the five mechanisms. Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.

6. Average damage scores, for each of the mechanisms, for seventy-one patellar components, ac- cording to whether the implant had been in situ for two years or less or for more than two years. Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.

7. Average damage scores, for each of the mechanisms, for the eighty-five patellar components, according to the design type (dome-shaped, sombrero-shaped [dome with a flange], or pseudo- anatomic). Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.

8. Scanning electron microscopy images of two different retrieved patellar components, showing the transition from unworn areas with machining marks (A) to creep and burnishing to delamination (B). Michael A. Conditt et al. J Bone Joint Surg Am 2005;87:1265-1271 ©2005 by The Journal of Bone and Joint Surgery, Inc.