Comparative study of existing knee prosthesis with anthropometry of Indian patients and other races, a computer tomography 3D reconstruction-based study.

ABSTRACT

Background: Appropriate component sizing plays an important role in determining the functional outcome following total knee arthroplasty. Comparative studies of different populations have shown significant differences in the anthropometric parameters of knees in different race groups which negates the possibility of using a single sized implant system across different ethnic groups. This study evaluates the dimensions of femoral and tibial articular surfaces of Indian patients and compares the parameters with other ethnic groups and correlates the dimensions with five different commercially available knee systems.Material & Methods: Computerized tomography (CT) scans of contralateral normal knees of patients who underwent the scan for various ailments of the knee were retrieved retrospectively from the hospital database and 3D reconstruction of the images was done. Mediolateral dimensions (fML,tML), Anteroposterior dimensions (fAP, tAP) and aspect ratio (fML/fAP, tML/tAP) of the femur and tibia respectively were calculated and compared with the dimensions of different ethnic groups as well as the femoral and tibial components of five different knee prosthesis systems. RESULTS: The average fML in the study group was less than that of Caucasian knees but was marginally larger than other ethnic groups. The fAP, tML and tAP was found to be smaller than all other ethnic groups but a larger femoral aspect ratio was reported than other ethnic groups. Among the implant systems, only NexGen LPS and Scorpio NRG implant femoral components closely matched the femoral dimensions in the study group whereas all implant systems showed significant mismatch with tibial component dimensions when compared to the study populations. CONCLUSION: This study concludes that the dimensions of Indian knees are different from other ethnic groups and the use of commercially available knee Implants designed based on measurements in Caucasian populations can lead to significant mismatch between implant and resected bone surfaces.