Anthropometric measurements to design best-fit femoral stem for the Indian population

Abstract

Background:The standard commercially available marketed prostheses sometimes may not be the best fit to Indian patients because of the large anatomic variation. Orthopedic surgeons always stress the need for a proper implant–patient match in hip joint replacements, in particular, for a cementless femoral stem. The complications of mismatch are aseptic loosening, improper load distribution, and discomfort. The present study was undertaken to compare the differences in dimensions between femurs of elderly Indians and those of populations from other regions in order to solve the problem of a possible geometric mismatch between a selected implant and the hip joint as far as Indian patients are concerned.Materials and Methods:Measurements were made using computer aided design techniques on computed tomography (CT) scanned images of 98 femurs (56 left and 42 right). The software used to convert the CT images into solid models was MIMICS® (Materialize, Inc., Leuven, Belgium). The geometrical parameters, viz., the femoral head offset, femoral head center (HC), femoral head diameter, femoral head relative position, position of shaft isthmus, neck-shaft angle, bow angle, femoral neck length, canal flare index, femoral length, and canal width at various locations, were chosen to design best-fit standard femoral stems for cementless insertion. These data were compared with the published data of other countries.Results:A difference of 16.8% was found in the femoral head offset between Indian and Swiss populations, which can affect soft tissue tension and range of motion. At a distance of 20 mm above the lesser trochanter (LT), the anteroposterior (AP) canal width was found to differ by 45.4%, when compared with a French population which can affect the mechanical stability of femoral stem. Femoral dimensions of Indian male and female subjects have also been compared and differences evaluated. At the LT, the aspect ratio (ratio of mediolateral canal width and AP canal width) in case of males (1.198) is approximately13% higher than that of females (1.059).Conclusions:This study indicates a need for redesign of femoral stems. The obtained anthropometric femoral dimensions can be used to design and develop indigenous hip joint prosthesis in India. The results of this study can also be used in forensic anthropometric studies.

Are the Left and Right Proximal Femurs Symmetric?

“…The dimensions of the femur are affected by gender and ethnicity [8,16,20,26,31,40,43,44]. Other than a small correlation between increased height and increased AP femoral head symmetry, there was no association between asymmetry and age, weight, height, ethnicity, and gender.…”

“…Proximal femoral anatomy has been the subject of numerous studies owing to the success of hip arthroplasty worldwide [5,6,15,18,31,43], and as a result of the discovery that certain femoral disorders, such as femoral acetabular impingement and Legg-Calvé-Perthes disease, can lead to osteoarthritis [1,11,13,41]. The investigators who have examined symmetry have studied bone properties and cortex thickness [28,32,36,40], with few studying dimensions [3,28].…”

Study of Proximal femoral Anthropometry in Population of Eastern Madhya Pradesh

“…The results of this study indicate that marked differences do exist in the dimensions between the femur of the Indian population and that of the populations of other regions of the world 11 . For Indian population best fit prosthesis can be made with the help of the published data of proximal femur.…”

“…The proximal femoral parameters are very important structural and functional specialization for mans erect posture 5 There are regional differences in the stature of human beings so prosthesis should be designed according to specific population 4 . It is vital to match the dimensions of the implant closely with those of the femur, as some of the complications resulting from mismatch could be aseptic loosening, improper load distribution and discomfort 11 .…”

Femoral Head Fovea Capitis Variant Configurations and Age Related Changes- A Radiological Study

“…This can be explained mostly by the smaller left femoral head diameter compared to the right ones as demonstrated before by many researchers (16)(17)(18).…”