Open Access

Differences in hip morphology between the sexes in patients undergoing hip resurfacing

  • Henry D Atkinson1, 2Email author,
  • Karanjeev S Johal1,
  • Charles Willis-Owen2,
  • Steven Zadow2, 3 and
  • Roger D Oakeshott2
Journal of Orthopaedic Surgery and Research20105:76

DOI: 10.1186/1749-799X-5-76

Received: 14 May 2010

Accepted: 15 October 2010

Published: 15 October 2010

Abstract

There is limited morphological data on the sex differences between the commonly used pelvic parameters. This study analysed the CT scans of 100 consecutive Caucasian patients, 61 males and 39 females, undergoing hip resurfacing arthroplasty surgery for hip osteoarthritis in one institution.

There were no sex differences in femoral torsion/anteversion, femoral neck angle and acetabular inclination. Males had a mean femoral torsion/anteversion of 8 degrees (range -5 to 26 degrees), a mean femoral neck angle of 129 degrees (range 119 to 138 degrees) and a mean acetabular inclination of 55 degrees (range 40 to 86 degrees). Females had a mean femoral torsion/anteversion of 9 degrees (range -2 to 31 degrees), a mean femoral neck angle of 128 degrees (range 121 to 138) and a mean acetabular inclination of 57 degrees (range 44 to 80 degrees). Females had a significantly greater acetabular version of 23 degrees (range 10 to 53) compared with 18 degrees in males (range 7 to 46 degrees (p = 0.02) and males had a significantly greater femoral offset of 55 mm (range 42 to 68 mm) compared with 48 mm (range 37 to 57 mm) in females (p = 0.00). There were no significant differences between measurements taken from each patient's right and left hips.

These findings may be useful for the future design and the implantation of hip arthroplasty components.

Introduction

Metal on metal hip resurfacing is a modality of treatment that been shown to be an effective medium term solution for young adults with hip osteoarthritis[1]. Its principle is to preserve femoral bone stock and thus make any future revision surgery more amenable [2].

Accurate placement of the hip resurfacing components has an impact on the clinical outcomes. In particular, varus angulation of the femoral component and femoral neck notching have been shown to be risk factors for neck of femur fracture [3], and inadequate cup anteversion has a significant impact on hip flexion and edge loading [4].

Pre-operative calculations of femoral torsion, version and offset as well as acetabular version and inclination have been previously undertaken using plain radiographs [5, 6], and subsequently more accurately using CT scanning [7]. The use of CT guidance in the placement of prostheses has been shown to significantly improve the post-operative component positions compared with freehand techniques [8]. CT scanning may also identify other anatomical anomalies and the presence of femoral head/neck cysts that may not be apparent on plain radiography [9].

Differences between male and female pelvic morphology may also be an important factor. Studies in childhood have demonstrated no difference in femoral anteversion between the sexes [10], however there may be differences in adults [1117]. There continues to be very limited data on the sex differences between the commonly used pelvic parameters.

This study prospectively collected data from the CT scans of 100 consecutive Caucasian patients undergoing hip resurfacing for early osteoarthritis, analysing each of the patient's two hips for femoral neck angle, torsion and offset, and acetabular inclination and anteversion, and comparing the sexes. This, to our knowledge, is the first study of its kind.

Patients and Methods

100 consecutive Caucasian patients, 61 males and 39 females (mean age 52 and 54 respectively), underwent pelvic CT scanning as part of their routine work-up for hip resurfacing arthroplasty surgery for hip osteoarthritis, between March 2007 and October 2008 in one institution.

The radiographic measurements were performed by two independent investigators. Repeated measurements were also taken in a random order to check for intraobserver error. The radiographic parameters measured included the femoral neck angle, femoral torsion, femoral offset, acetabular version and acetabular inclination.

The acetabular inclination was calculated by plotting a trans-ischial line on the pilot image, and a second line drawn across the superior and inferior rims, across the face of the bony acetabulum [18]. The inclination angle was formed by the intersection of these lines (Figure 1).
Figure 1

The acetabular inclination calculated by plotting a trans-ischial line, and intersecting this with a second line drawn across the superior and inferior acetabular rims.

The acetabular version was calculated by plotting a trans-ischial line across the ischial tuberosities on the axial CT image. The trans-ischial line was then transposed to an axial image of the acetabulum, and a second line was drawn across the anterior and posterior margins of the bony acetabulum. The anteversion angle was formed by the intersection of these two lines (Figure 2).
Figure 2

The acetabular version calculated by plotting a trans-ischial line across the ischial tuberosities on axial CT image. A second line is drawn across the anterior and posterior margins of the bony acetabulum. The anteversion angle is formed by the intersection of these two lines.

The femoral torsion was determined by plotting a reference line through the transcondylar plane of the distal femur, and plotting a second line through the axis of the neck of the femur. Superimposition of these lines gave the femoral torsion angle (Figure 3).
Figure 3

The femoral torsion is determined by plotting a reference line through the transcondylar plane of the distal femur, and superimposing a second line through the axis of the neck of the femur.

The femoral neck angle was determined by plotting a line along the axis of the femoral neck and a second line along the long axis of the femur. The transection of these lines gave the femoral neck angle (Figure 4).
Figure 4

The femoral neck angle determined by plotting a line along the axis of the femoral neck and a second line along the long axis of the femur.

The femoral offset was determined as the distance from the centre of rotation of the femoral head to the line bisecting the long femoral axis (Figure 5) [19].
Figure 5

The femoral offset determined as the distance from the centre of rotation of the femoral head to a line bisecting the long femoral axis.

Data were statistically analyzed using the Friedman non-parametric test allowing for two-way analysis of variance, after Kolmogorov-Smirov analysis. Data were also analyzed using the Wilcoxon Signed Ranks Test. A 2-tailed comparison was made of patients' left and right hip data using Spearman's correlation tests.

Results

The analyzed results demonstrated no sex differences in femoral torsion/anteversion, femoral neck angle and acetabular inclination (Table 1). Males had a mean femoral torsion/anteversion of 8 degrees (range -5 to 26 degrees), a mean femoral neck angle of 129 degrees (range 119 to 138 degrees) and a mean acetabular inclination of 55 degrees (range 40 to 86 degrees). Females had a mean femoral torsion/anteversion of 9 degrees (range -2 to 31 degrees), a mean femoral neck angle of 128 degrees (range 121 to 138) and a mean acetabular inclination of 57 degrees (range 44 to 80 degrees).
Table 1

Demonstrates no differences in femoral torsion or femoral neck angle between the sexes

 

Sex

N

Mean Rank

Sum of Ranks

Significance

Femoral Torsion/deg

Male

61

45.04

2522.00

Z=-0.865

 

Female

39

49.97

1849.00

p = 0.387

 

Total

100

  

No significance

Femoral Neck Angle/deg

Male

61

137.43

2656.00

Z=-0.189

 

Female

39

136.35

1715.00

p = 0.850

 

Total

100

  

No significance

Females had a significantly greater acetabular version of 23 degrees (range 10 to 53) compared with 18 degrees in males (range 7 to 46 degrees (p = 0.02) and males had a significantly greater femoral offset of 55 mm (range 42 to 68 mm) compared with 48 mm (range 37 to 57 mm) in females (p = 0.00) (Table 2). There were no significant differences between measurements taken from each patient's right and left sides (Tables 3 and 4). There was no significant difference in the proportion of acetabular or femoral dysplasia between the sexes.
Table 2

Demonstrates differences in the acetabular version and femoral offset between the sexes

 

Sex

N

Mean

Std. Deviation

Std. Error Mean

Significance t-test and p

Significance

Acetabular Version/deg

Male

61

17.2

9.28

1.240

t = 2.320

*

 

Female

39

22.59

10.33

1.698

p = 0.023

 

Acetabular Inclination/deg

Male

61

54.89

7.23

0.967

t = -1.115

None

 

Female

39

56.65

7.73

1.270

p = 0.260

 

Femoral Offset/mm

Male

61

55.36

5.82

0.778

t = 6.000

**

 

Female

39

48.17

5.19

0.853

p = 0.000

 

* Females have greater acetabular version

** Males have a greater femoral offset

Table 3

Demonstrates no significant differences between measurements taken from each patient's right and left hips

 

Paired Samples Statistics

Mean

N

Std. Deviation

Std. Error Mean

Significance

Significance

Pair 1

Acetabular Version/deg

70.08

100

10.11

1.69

t = 1.546

No

 

Acetabular Version/deg

68.72

100

11.01

1.84

p = 0.131

 

Pair 2

Acetabular Inclination/deg

56.50

100

7.09

1.18

t = 0.199

No

 

Acetabular Inclination/deg

56.31

100

8.85

1.47

p = 0.844

 

Pair 3

Femoral Offset/mm

52.14

100

6.79

1.13

t = 0.799

No

 

Femoral Offset/mm

51.66

100

6.71

1.12

p = 0.430

 
Table 4

Demonstrates no significant differences between measurements taken from each patient's right and left hips

Test Statisticsc

 

Femoral Torsion/deg - Femoral Torsion/deg

Femoral Neck Angle/deg - Femoral Neck Angle/deg

Z

-1.40a

-0.995b

Asymp. Sig. (2-tailed)

0.161

0.320

a. Based on negative ranks.

b. Based on positive ranks.

c. Wilcoxon Signed Ranks Test

There was no significant intraobserver (P = 0.72, Wilcoxon rank test) or interobserver error (P = 0.19, Friedman test).

Discussion

This study has demonstrated significant differences in the femoral offset and acetabular version between males and females, with no significant differences between the other pelvic morphological parameters. Males had a greater femoral offset, and females had greater acetabular version. These results differ from the literature where females have been reported as having greater femoral neck anteversion and lower femoral neck-shaft angles [1217]. This discrepancy may be the result of the racial uniformity seen in our patient group; certainly racial variations in hip morphology have been previously reported [20, 21]. A study of 50 white women and 50 black women found that hip axis length and the neck width were significantly longer in the white women, while neck/shaft angles were not statistically different in the two groups [20].

This study also found no significant differences in morphology between patients' right and left hips, which is also contrary to findings from another study which concluded that side-specific prostheses should be manufactured [22].

While adjustments to anatomically restore the femoral offset and femoral version are possible using modular neck prostheses in total hip arthroplasty [12], we believe that attention should also be paid to the natural acetabular version. We emphasise the importance of pre-operative CT scanning in accurately determining these parameters, to allow for optimum component positioning, particular in the context of hip resurfacing arthroplasty.

Consent

Written informed consent was obtained from all patients for their data inclusion in this and other research at our Institution. Copies of these consent forms are available for review by the Editor-in-Chief of this journal

Abbreviations

CT: 

Computed Tomography

Declarations

Acknowledgements

The authors would like to thanks Belinda Grygorcewicz, St Andrews Hospital Radiology Department, 350 South Terrace, Adelaide SA 5000 for all her assistance in the data collection

Authors’ Affiliations

(1)
Department of Trauma and Orthopaedics and North London Sports Orthopaedics, North Middlesex University Hospital
(2)
Sportsmed SA
(3)
St Andrews Hospital Radiology Department, 350 South Terrace

References

  1. Treacy RBC, McBryde CW, Pynsent PB: Birmingham hip resurfacing arthroplasty. A minimum of five years follow up. J Bone Joint Surg [Br]. 2005, 87 (2): 167-70.View ArticleGoogle Scholar
  2. Wagner H: Surface replacement arthroplasty of the hip. Clin Orthop Relat Res. 1978, 102-30. 134
  3. Shimmin AJ, Back D: Femoral neck fractures following Birmingham hip resurfacing. J Bone Joint Surg [Br]. 2005, 87-B: 463-4.View ArticleGoogle Scholar
  4. Malviya A, Lingard EA, Malik A, Bowman R, Holland JP: Hip Flexion After Birmingham Hip Resurfacing: Role of Cup Anteversion, Anterior Femoral Head-Neck Offset, and Head-Neck Ratio. J Arthroplasty. 2010, 25 (3): 387-91. 10.1016/j.arth.2009.01.026.View ArticlePubMedGoogle Scholar
  5. Hermann KL, Egund N: Measuring anteversion in the femoral neck from routine radiographs. Acta Radiol. 1998, 39 (4): 410-5.View ArticlePubMedGoogle Scholar
  6. Jamali AA, Mladenov K, Meyer DC, Martinez A, Beck M, Ganz R, Leunig M: Anteroposterior pelvic radiographs to assess acetabular retroversion: high validity of the "cross-over-sign". J Orthop Res. 2007, 25 (6): 758-65. 10.1002/jor.20380.View ArticlePubMedGoogle Scholar
  7. Hermann KL, Egund N: CT measurement of anteversion in the femoral neck. The influence of femur positioning. Acta Radiol. 1997, 38 (4 Pt 1): 527-32.PubMedGoogle Scholar
  8. Bailey C, Gul R, Falworth M, Zadow S, Oakeshott R: Component alignment in hip resurfacing using computer navigation. Clin Orthop Relat Res. 2009, 467 (4): 917-22. 10.1007/s11999-008-0584-x.PubMed CentralView ArticlePubMedGoogle Scholar
  9. Torricelli P, Reggiani G, Martinelli C, Boriani S, Folchi Vici F: Value and limitations of computerized tomography in the study of benign tumors of the bone. Radiol Med. 1987, 74 (5): 388-95.PubMedGoogle Scholar
  10. Upadhyay SS, Burwell RG, Moulton A, Small PG, Wallace WA: Femoral anteversion in healthy children. Application of a new method using ultrasound. J Anat. 1990, 169: 49-61.PubMed CentralPubMedGoogle Scholar
  11. Nagar M, Bhardwaj R, Prakash R: Anteversion In Adult Indian Femora. Journal of the Anatomical Society of India. 49 (1): (2000-01 - 2000-06)
  12. Traina F, De Clerico M, Biondi F, Pilla F, Tassinari E, Toni A: Sex differences in hip morphology: is stem modularity effective for total hip replacement?. J Bone Joint Surg Am. 2009, 91 (Suppl 6): 121-8. 10.2106/JBJS.I.00533.View ArticlePubMedGoogle Scholar
  13. Nieves JW, Formica C, Ruffing J, Zion M, Garrett P, Lindsay R, Cosman F: Males have larger skeletal size and bone mass than females, despite comparable body size. J Bone Miner Res. 2005, 20: 529-35. 10.1359/JBMR.041005.View ArticlePubMedGoogle Scholar
  14. Noble PC, Alexander JW, Lindahl LJ, Yew DT, Granberry WM, Tullos HS: The anatomic basis of femoral component design. Clin Orthop Relat Res. 1988, 235: 148-65.PubMedGoogle Scholar
  15. Wang SC, Brede C, Lange D, Poster CS, Lange AW, Kohoyda-Inglis C, Sochor MR, Ipaktchi K, Rowe SA, Patel S, Garton HJ: Gender differences in hip anatomy:possible implications for injury tolerance in frontal collisions. Annu Proc Assoc Adv Automot Med. 2004, 48: 287-301.PubMed CentralPubMedGoogle Scholar
  16. Kaptoge S, Dalzell N, Loveridge N, Beck TJ, Khaw KT, Reeve J: Effects of gender, anthropometric variables, and aging on the evolution of hip strength in men and women aged over 65. Bone. 2003, 32: 561-70. 10.1016/S8756-3282(03)00055-3.View ArticlePubMedGoogle Scholar
  17. Sariali E, Mouttet A, Pasquier G, Durante E: Three-dimensional hip anatomy inosteoarthritis analysis of the femoral offset. J Arthroplasty. 2009, 24: 990-7. 10.1016/j.arth.2008.04.031.View ArticlePubMedGoogle Scholar
  18. Murray DW: The definition and measurement of acetabular orientation. J Bone Joint Surg Br. 1993, 75 (2): 228-32.PubMedGoogle Scholar
  19. Lecerf G, Fessy MH, Philippot R, Massin P, Giraud F, Flecher X, Girard J, Mertl P, Marchetti E, Stindel E: Femoral offset: Anatomical concept, definition, assessment, implications for preoperative templating and hip arthroplasty. Orthopaedics & Traumatology: Surgery & Research. 2009, 95 (3): 210-219.Google Scholar
  20. Lavy CB, Msamati BC, Igbigbi PS: Racial and gender variations in adult hip morphology. Int Orthop. 2003, 27 (6): 331-3. 10.1007/s00264-003-0507-0.PubMed CentralView ArticlePubMedGoogle Scholar
  21. Mikhail MB, Vaswani AN, Aloia JF: Racial differences in femoral dimensions and their relation to hip fracture. Osteoporos Int. 1996, 6 (1): 22-4. 10.1007/BF01626533.View ArticlePubMedGoogle Scholar
  22. Vandenbussche E, Saffarini M, Taillieu F, Mutschler C: The Asymmetric Profile of the Acetabulum. Clin Orthop Relat Res. 2008, 466 (2): 417-423. 10.1007/s11999-007-0062-x.PubMed CentralView ArticlePubMedGoogle Scholar

Copyright

© Atkinson et al; licensee BioMed Central Ltd. 2010

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.