QUESTIONS FOR THE ORTHOPEDIC AND REHABILITATION DEVICES ADVISORY PANEL.  

RE:  total mobile bearing knee components and unicompartmental mobile bearing knee components.                                                                                                        

 

The Orthopedic Surgical Manufacturers Association (OSMA) has submitted a reclassification petition for two general types of mobile bearing knee prostheses.  The petition seeks reclassification from Class III (premarket approval) to Class II (special controls) for both total {patellofemorotibial} and unicompartmental {femorotibial} mobile bearing knee systems.  The petition seeks to include both cemented and uncemented versions within each of these device configurations.

 

1.     Do you believe the proposed classification definitions for the following device configurations recommended for reclassification adequately describe the devices?  If not, what changes in the definitions do you recommend?

 

      a.   Total mobile bearing knee prosthesis

           

      b.      Unicompartmental mobile bearing knee prosthesis

 

2.     Do you believe the risks to health of the following device configurations proposed for reclassification are adequately described?  If not, what additional risks do you believe should be included?

 

      a.   Total mobile bearing knee prosthesis

           

      b.      Unicompartmental mobile bearing knee prosthesis

 

3.   Special controls have been proposed to address the risks to health identified for each of the above device configurations (and all related ‘sub-configurations’).  Please respond to the following questions regarding specific risks and/or special controls:

 

a.        Dislocation and subluxation of mobile bearing components have been cited as common complications in the literature. 

 

                                                            i.      Do you believe appropriate special controls have been identified to adequately address these risks?

                                                           ii.      If not, what additional controls, if any, do you recommend to address these risks?

 

b.       A reduction in wear is often cited as a theoretical advantage of mobile bearing knees over fixed bearing devices.  However, this has not been consistently demonstrated clinically, and it is not clear how well preclinical wear testing of mobile bearing knees correlates to the clinical situation.  In addition, the potential for third body wear appears greater (due to two moving interfaces instead of one) and the potential for the amount of third body wear also appears to be greater.  Currently, the state of development of knee simulator wear testing has not yet been standardized or clinically validated across all device types, and therefore may not be applicable for all of the various mobile bearing knee types identified in this petition.

 

                                                            i.      In light of the fact that wear appears to be, in part, design dependent, do you believe appropriate controls have been identified to adequately address the risk of wear (i.e., osteolysis, loosening) for the various mobile bearing knee designs under consideration in this petition? 

                                                           ii.      If not, what additional controls, if any, do you recommend to address this risk?

 

c.        Although labeling has been cited as a control with which to address risks to health, the proposed labeling requirements are consistent with those generally found in current fixed bearing total and unicompartmental knee package labeling.  Labeling typically includes device description, type of material, indications for use, contraindications, adverse events, precautions, warnings, a listing of compatible components, and sterility information. 

 

                                                            i.      What additional labeling, if any, do you recommend for these mobile bearing knee components? 

       

d.     Do you believe appropriate special controls have been identified to adequately address the risks to health for each of the above device configurations (and all ‘sub-configurations’)?  If not, what other special controls do you recommend to address the risks presented by these devices?

 

4.             Do you believe the data presented in this petition supports the reclassification of:

 

a.     All total mobile bearing knee prostheses identified in this petition?  If not, which types of total knees do you believe are inappropriate for reclassification, and why (e.g., they have insufficient information and/or special controls)?

 

b.    All unicompartmental mobile bearing knee prostheses identified in this petition?  If not, which types of unicompartmental knees do you believe are inappropriate for reclassification, and why (e.g., they have insufficient information and/or special controls)?