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Year : 2003  |  Volume : 37  |  Issue : 4  |  Page : 247-251
Anthropometric study of proximal femur geometry and its clinical application


Department of Orthopaedics, Paraplegia & Rehabilitation, Postgraduate Institute of Medical Sciences, Rohtak, India

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   Abstract 

Seventy five pairs (150 bones) of cadaveric femora were studied morphologically and radiologically using standardized techniques to obtain the following anthropometrics measurements: femoral head offset, femoral head diameter, femoral head position, femoral neck diameter, canal width at the level of and 20mm above and below the lesser trochanter, endosteal and extracortical width at the isthmus, isthmus position, femoral neck anteversion and neck shaft angle. The mean and S.D. of these values were calculated. The measurements were used to calculate femoral head volume and cross sectional area of the femoral neck. Percentage of the neck occupied by various implants was calculated. These values were compared with those reported in the literature for Hong Kong Chinese, Caucasian, Chinese and Westerns. Data was found to be quite different from them. The impact of these findings on future implant design in India is discussed. It is proposed that implants designed for Western populations should be used judiciously and future implant designed customized to suit the Indian bones.

Keywords: Proximal end femur - Anthropometric measurements - Western vs. Indian standards

How to cite this article:
Siwach R C, Dahiya S. Anthropometric study of proximal femur geometry and its clinical application. Indian J Orthop 2003;37:247-51

How to cite this URL:
Siwach R C, Dahiya S. Anthropometric study of proximal femur geometry and its clinical application. Indian J Orthop [serial online] 2003 [cited 2018 Dec 13];37:247-51. Available from: http://www.ijoonline.com/text.asp?2003/37/4/247/48488

   Introduction Top


Operations on the proximal femur are one of the commonest in Orthopaedic surgical practice. The aim of these operations is to remove pathology and restore anatomy to the normal, as far as possible. Whereas what is normal has been standardized for Caucasians and Chinese [1] , data for Indians is lacking. Since build, physique, habits and genetic make up vary markedly in different ethnic groups, it is possible that anthropometric dimensions described as normal for proximal end femur for Westerners might be quite different from those encountered amongst Indians. The present study was conducted with aim to remove the lacuna of information about proximal femoral geometry in Indian people and evaluate its impact on implant design.


   Material and Methods Top


The study was conducted on 150 adult cadaveric femora. Specimens that showed osseous pathology or previous fractures were excluded from the study. With the help of forensic expert these 150 adult cadaveric femora were differentiated into male and female femora, and their approximate age was determined. We did study on femora of adult group (age approximately between 20 year to 80 years). Roentgenograms of 75 pairs of near identical specimen were taken in anteroposterior and lateral views using a precise standardized technique.

The specimens were placed directly over the cassette so the magnification would be insignificant. The distance between the X-ray source and the film was 1.2 m and the beam was centered on the lesser trochanter with the femur lying in neutral rotation.

For lateral view without moving the femur, the X-ray source was rotated through 90 0 in the vertical plane, the distance between the source and the film remaining the same. Then the femur was kept on a sponge of the 2 feet length, 10" breadth and 8" height; the X-ray cassette was kept touching the femur, with one technician holding the cassette after wearing a lead apron. But on these lateral views the whole neck profile was not clear due to superimposition of greater trochanter. So to avoid this problem we kept the femur directly on the cassette in frog leg view position holding the condyles of the femur. In this view the neck profile of femur was clear.

Morphological study

The standard extracortical and endosteal dimensions were determined by direct measurement of cadaveric specimens. These measurements were done with the help of vernier caliper and goniometer.

With the help of vernier caliper we measured femoral head diameter, femoral head length, effective neck length, neck diameter and canal width 20mm above lesser trochanter, at level of lesser trochanter and 20 mm below lesser trochanter [Figure 1]. With the help of goniometer neck shaft angle and angle of anteversion were measured [Figure 2].

Radiological study

A center point was marked at the level of isthmus. Second point was marked at the center of femur 3cm above isthmus and third point was marked at the center of femur 3 cm below isthmus, a line connecting these 3 points was drawn and extended upwards and downwards.

With the help of scale we measured femoral head offset, femoral head diameter, femoral head position, neck diameter, canal width 20mm above lesser trochanter, canal width at level of lesser trochanter, canal width 20mm below lesser trochanter, endosteal width at the isthmus and extracortical width at the isthmus and isthmus position [Figure 3]. With the help of goniometer the neck shaft angle was measured.


   Observations Top


The average values of the morphological parameters studied, their standard deviation, minimum and maximum values and comparison with Western and Asian (Chinese and Caucasians in Hong Kong) is depicted in [Table 1].

[Table 2] shows the radiological aspect of all the morphological measurements. Femoral head volume was calculated using the formula p d 3 /6 where d is the diameter of head. The volume of implants in the femoral head was calculated using d 2 /4 x l where d is diameter of femoral head and l is length of implant {l =2/3 d-10mm (subchondral bone left)}. [Table 3] depicts the percentage of femoral head volume occupied by various implants in different populations. [Table 4] represents the percentage of cross sectional area of neck p d 2 /4 occupied by various implants Cross sectional area of femoral neck is calculated by Formula p d 2 /4 (d=diameter). [Table 5] represents the comparison of femoral neck anteversion in various ethnic groups.


   Discussion Top


It is the bane of Indian orthopaedic surgeon to implant devices and prosthesis designed for Western skeletons. Not only are these implants large in size, their angles, and orientations and thread length also mismatch Indian femora. Any alteration of the normal physiology or anatomy is likely to affect the end functional result. As is evident from a perusal of [Table 1], most of the parameters in Indian femora differ markedly from other ethnic groups e.g. the average femoral head is lesser than the average Western value by as much as 5mm. Similarly the other anthropometric measurements can be seen to vary markedly from the Western values[Figure 4]. It can also be seen from [Table 3] and[Table 5] that implants designed for western skeletons occupy much more space in the Indian femoral head and neck [Figure 5].

These observations have profound implications. They imply that a certain subset of Indian femora do not have any implant available to them as they are too small. Furthermore, a shorter neck length implies that the threads of cancellous or Garden screws used to fix neck fractures may not cross the fracture site thereby failing to provide compression and thus defeating the whole purpose of the surgery [Figure 6]. It was observations like these that prompted Leung et al to modify the gamma nail to suit the Asian Population. [2],[3],[4] If too much bone is replaced by metal a tamponade effect can ensue that may cause avascularity of femoral head, consequently resulting in nonunion of neck fractures and/or AVN. Since our heads are smaller, the threads of screws often fail to cross the fracture of neck of femur especially if the fracture is sub capital and the screw placement in the inferior quadrant of head. This means we must have screws with shorter thread lengths. In thin built and short individuals the neck may not have space enough to occupy the three 6.5 mm screws recommended for fixation of neck fractures. A smaller neck shaft angle implies that a DHS inserted through the classical entry portal using angled guide will either go into the superior quadrant or pull the fracture in valgus both of which are undesirable. We probably require DHS with smaller angles.

The implications of the study on arthroplasty operations can't be overemphasized as these are designed to reproduce the normal anatomy as far as possible.

Numerous published reports have underlined the importance of close geometric fit between the femur and the implanted stem. In cemented prosthesis, it is desirable to have 2 mm cement mantle around the prosthesis. A strong correlation has been established between the occurrence of thigh pain and inadequate fit and fixation of the implant. The clinical symptoms are due to the bone­implant mismatch, which result in micromotion. There are studies, which highlight that these micromotions should be reduced to 14 micra or less, to prevent osteolysis and aseptic loosening. [5] The incidence of intraoperative complications like splintering and fractures ranges from 4 to 21%. These are due to over-sized implants available that have been manufactured basically with western parameters [Figure 7]. Geometry of the proximal femur is determined by a large number of genetic and environmental factors including age, race, sex and lifestyle. [6],[7] Many studies have demonstrated the clinical importance of a close match between the dimension of the femur and the implanted prosthesis. [8],[9],[10]

Acknowledgements:

The authors are grateful to the kind advice and help rendered by following during the study.

Prof. SS Sangwan (Prof & head Orthopaedics, PGIMS Rohtak), Prof KC Mudgal (Ex-Prof & head-II Orthopaedics, PGIMS Rohtak), Dr. SK Dhattarwal (Associate Prof Forensic Medicine, PGIMS Rohtak), Department of Anatomy PGIMS Rohtak, Department of Forensic Medicine, PGIMS Rohtak, Prof. Dalbir Singh (Head of Department of Forensic medicine, PGI Chandigarh), Prof. O.N. Nagi (Head of Department of Orthopaedics, PGI Chandigarh), Dr. Anil Kr Jain (UCMS, Delhi), Prof. K.P. Srivastava (Agra), Prof. DK Taneja (Indore), Dr. KD Sangwan (ex­SR PGIMS) .

 
   References Top

1.Hoaglund FT, Low WD. Anatomy of the femoral neck and head, with comparative data from Caucasians and HongKong Chinese. Clin Orthop 1980:152: 10-16.  Back to cited text no. 1    
2.Leung K, Procter P, Robioneck B, Behrens K. Geomet­ric mismatch of the gamma nail to the Chinese femur. Clin Orthop 1996: 323: 42-8.  Back to cited text no. 2    
3.Leung KS. Early experience with gamma nails in the treat­ment of peritrochanteric fractures. Trans Hong Kong Orthop Assoc 1989; 33; .  Back to cited text no. 3    
4.Leung KS, So WS, Shen WY, Hui PW. Gamma nails and dynamic hip screws for peritrochanteric fractures. J Bone Joint Surg [Br] 1992; 74B: 345-51.  Back to cited text no. 4    
5.Reddy VS, Moorthy GVS, Reddy SG. Do we need a spe­cial design of femoral component of total hip prosthesis in our patients? Ind J Orthop 1999; 33(4): 282-4.  Back to cited text no. 5    
6.El Najjar MY, McWilliams KR. Forensic Anthropol­ogy: The structure, Morphology and variations of hu­man bone and dentition. Springfield; Charles C Tho­mas.1978.  Back to cited text no. 6    
7.Ericksen MF. Ageing changes in the medullary cavity of the proximal femur in American black and whites. Am J Phys Anthropol 1979; 51: 563-9.  Back to cited text no. 7  [PUBMED]  
8.Engh CA. Hip arthroplasty with a Moore prosthesis with porous coating: A five year study. Clin Orthop 1983; 176: 52-66.  Back to cited text no. 8  [PUBMED]  [FULLTEXT]
9.Harris WH. The porous total hip replacement system: surgical technique. In Harris WH (Ed) Advanced con­cepts in total hip replacement. New Jersy; Slack.1985.  Back to cited text no. 9    
10.Noble PC, Jerry W, Alexander JW, Lindhal LJ, Yew DT, Granberry WM, Tullos HS. The anatomical basis of femoral component design. Clin Orthop 1988; 235: 148­-65.  Back to cited text no. 10    

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Correspondence Address:
R C Siwach
31/9 J, Medical Enclave, PGIMS, Rohtak-124001 Presented at IOACON 2002, Patna
India
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Source of Support: None, Conflict of Interest: None


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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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    Abstract
    Introduction
    Material and Methods
    Observations
    Discussion
    References
    Article Figures
    Article Tables
 

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