New Data Supports Use of Conformis Customized Knee Implants to Match Anatomic Variability

Conformis Inc., a medical technology company that uses its proprietary iFit Image-to-Implant technology platform to develop, manufacture, and sell joint replacement implants customized to fit each patient’s unique anatomy, today announced the publication of peer reviewed data in the journal Clinical Orthopedics and Related Research which analyzed CT scan information from a population of over 24,000 patients.  The study, “What Is the Possible Impact of High Variability of Distal Femoral Geometry on TKA?  A CT Data Analysis of 24,042 Knees,” can be found here.
 
The results of this study quantified a high degree of anatomic variability within the study population in both distal (DCO) and posterior (PFO) femoral offsets (see pictures below), supporting the adoption of customized implant systems for a significant number of patients. 
 
Publically available information on the design for standard or off-the-shelf (“OTS”) symmetric and fixed asymmetric implants was analyzed against the data derived from patient CT scans in this study. The results demonstrated that the OTS implant designs would not match the patient knee geometry and therefore, would not address or account for the femoral offset geometries in more than half of the patients’ population in this study.
 
There are two weight-bearing structures of the femur that articulate with the surface of the tibia: the medial and lateral femoral condyles. The native knee typically has differences in geometry of these femoral condyles both at the front, or distal elements (DCO), and on the back, or posterior elements (PFO), commonly referred to as condylar offset.  Since OTS implants have a limited number of sizes, they cannot address these condylar offsets for patients knee implants. 
 
In addition to the condylar offsets, the study investigators reviewed the dimensions of the knees for the patient population from the CT scans and found that, compared to the OTS available sizes, approximately one-third of the patients would have 3mm or more a size mismatch if the closest size was chosen. Size mismatch 3mm or more particularly when implants are too large has been linked to residual pain, which can be prevalent among women.  Use of customized knee implants can minimize such size mismatching.
 
“Our results demonstrate the wide variability of knee anatomy among the general population,” said Professor Johannes Beckmann of SportKlinik Stuttgart, Stuttgart Germany. “One of the biggest challenges we face as knee surgeons is to make OTS implants fit into disparate patient anatomies. The data clearly shows that standard OTS implants, which come in fixed sizes and geometries, do not typically match that variability. In my experience the only implant which enables me to accommodate for all of the different anatomies I encounter in the operating room is the patient-specific Conformis knee.”  
 
“This data supports what our engineers see on a daily basis when reviewing patient CT scans: a high percentage of anatomic variability exists within the general population,” said Mark Augusti, President and CEO of Conformis. “We believe this data contributes to understanding “why” a customized patient specific total knee implant provides improved patient comfort and kinematics as has been previously reported in our body of clinical evidence.”
 
Approximately 700,000 knee replacement procedures are performed annually in the US. This number is projected to increase to 3.48 million procedures per year by 2030¹.
Approximately 160,000 knee replacement procedures are performed annually in Germany².
 
References
¹ Kurtz S, Ong K, Lau E, et al. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007; 89:780.
² Analysis of Individual Inpatient Data From German and US Hospitals for the Years 2005 to 2011 Annelene Wengler, Dr. rer. pol.,1 Ulrike Nimptsch, Dr. rer. pol.,1 and Thomas Mansky, Prof. Dr. med.*,1